From 2045e42ba71c5d4cb99b8c6b74b1ef8359172d07 Mon Sep 17 00:00:00 2001
From: Jacob Coffee <jacob@z7x.org>
Date: Thu, 19 Mar 2026 13:05:57 -0500
Subject: [PATCH 1/7] better sidebar nav

---
 .../templates/django_program/manage/base.html | 86 ++++++++++++++++---
 1 file changed, 72 insertions(+), 14 deletions(-)

diff --git a/src/django_program/manage/templates/django_program/manage/base.html b/src/django_program/manage/templates/django_program/manage/base.html
index 7b7f237..870783c 100644
--- a/src/django_program/manage/templates/django_program/manage/base.html
+++ b/src/django_program/manage/templates/django_program/manage/base.html
@@ -159,6 +159,40 @@
       color: var(--color-text-muted);
       padding: 0 0.75rem;
       margin-bottom: 0.4rem;
+      display: flex;
+      align-items: center;
+      justify-content: space-between;
+      cursor: pointer;
+      user-select: none;
+      border-radius: var(--radius-sm);
+      transition: color 0.15s ease;
+    }
+    .sidebar-section-title:hover {
+      color: var(--color-text-secondary);
+    }
+    .sidebar-section-title .sidebar-collapse-icon {
+      width: 12px;
+      height: 12px;
+      flex-shrink: 0;
+      opacity: 0.5;
+      transition: transform 0.2s ease, opacity 0.15s ease;
+    }
+    .sidebar-section-title:hover .sidebar-collapse-icon {
+      opacity: 0.8;
+    }
+    .sidebar-section.collapsed .sidebar-collapse-icon {
+      transform: rotate(-90deg);
+    }
+    .sidebar-section.collapsed > .sidebar-nav {
+      max-height: 0;
+      overflow: hidden;
+      margin: 0;
+      opacity: 0;
+    }
+    .sidebar-section > .sidebar-nav {
+      max-height: 2000px;
+      opacity: 1;
+      transition: max-height 0.25s ease, opacity 0.2s ease;
     }
 
     .sidebar-sublabel {
@@ -999,8 +1033,8 @@
     {% if conference %}
     <nav class="sidebar" aria-label="Conference navigation">
       {# ── Conference ── #}
-      <div class="sidebar-section">
-        <div class="sidebar-section-title">{{ conference.name }}</div>
+      <div class="sidebar-section" data-section="conference">
+        <div class="sidebar-section-title">{{ conference.name }} <svg class="sidebar-collapse-icon" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round"><path d="M4 6l4 4 4-4"/></svg></div>
         <ul class="sidebar-nav">
           <li>
             <a href="{% url 'manage:dashboard' conference.slug %}" class="{% if active_nav == 'dashboard' %}active{% endif %}">
@@ -1016,8 +1050,8 @@
       </div>
 
       {# ── Program ── #}
-      <div class="sidebar-section">
-        <div class="sidebar-section-title">Program</div>
+      <div class="sidebar-section" data-section="program">
+        <div class="sidebar-section-title">Program <svg class="sidebar-collapse-icon" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round"><path d="M4 6l4 4 4-4"/></svg></div>
         <ul class="sidebar-nav">
           <li>
             <a href="{% url 'manage:section-list' conference.slug %}" class="{% if active_nav == 'sections' %}active{% endif %}">
@@ -1079,8 +1113,8 @@
       </div>
 
       {# ── Registration ── #}
-      <div class="sidebar-section">
-        <div class="sidebar-section-title">Registration</div>
+      <div class="sidebar-section" data-section="registration">
+        <div class="sidebar-section-title">Registration <svg class="sidebar-collapse-icon" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round"><path d="M4 6l4 4 4-4"/></svg></div>
         <ul class="sidebar-nav">
           <li class="sidebar-sublabel">People</li>
           <li>
@@ -1133,8 +1167,8 @@
       </div>
 
       {# ── Sponsors ── #}
-      <div class="sidebar-section">
-        <div class="sidebar-section-title">Sponsors</div>
+      <div class="sidebar-section" data-section="sponsors">
+        <div class="sidebar-section-title">Sponsors <svg class="sidebar-collapse-icon" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round"><path d="M4 6l4 4 4-4"/></svg></div>
         <ul class="sidebar-nav">
           <li>
             <a href="{% url 'manage:sponsor-level-list' conference.slug %}" class="{% if active_nav == 'sponsor-levels' %}active{% endif %}">
@@ -1150,8 +1184,8 @@
       </div>
 
       {# ── On-site ── #}
-      <div class="sidebar-section">
-        <div class="sidebar-section-title">On-site</div>
+      <div class="sidebar-section" data-section="onsite">
+        <div class="sidebar-section-title">On-site <svg class="sidebar-collapse-icon" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round"><path d="M4 6l4 4 4-4"/></svg></div>
         <ul class="sidebar-nav">
           <li>
             <a href="{% url 'manage:checkin-dashboard' conference.slug %}" class="{% if active_nav == 'checkin' %}active{% endif %}">
@@ -1167,8 +1201,8 @@
       </div>
 
       {# ── Finance & Insights ── #}
-      <div class="sidebar-section">
-        <div class="sidebar-section-title">Finance & Insights</div>
+      <div class="sidebar-section" data-section="finance">
+        <div class="sidebar-section-title">Finance & Insights <svg class="sidebar-collapse-icon" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round"><path d="M4 6l4 4 4-4"/></svg></div>
         <ul class="sidebar-nav">
           <li>
             <a href="{% url 'manage:financial-dashboard' conference.slug %}" class="{% if active_nav == 'financial' %}active{% endif %}">
@@ -1195,8 +1229,8 @@
 
       {# ── Sync & Overrides (utility) ── #}
       <hr class="sidebar-utility-separator">
-      <div class="sidebar-section">
-        <div class="sidebar-section-title">Sync & Overrides</div>
+      <div class="sidebar-section" data-section="sync-overrides">
+        <div class="sidebar-section-title">Sync & Overrides <svg class="sidebar-collapse-icon" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round"><path d="M4 6l4 4 4-4"/></svg></div>
         <ul class="sidebar-nav">
           <li>
             <div class="sidebar-nav-expandable">
@@ -1245,5 +1279,29 @@
   </div>
 
   {% block extra_js %}{% endblock %}
+  <script>
+  (function() {
+    var KEY = 'manage-sidebar-collapsed';
+    var stored = {};
+    try { stored = JSON.parse(localStorage.getItem(KEY) || '{}'); } catch(e) {}
+
+    document.querySelectorAll('.sidebar-section[data-section]').forEach(function(section) {
+      var id = section.dataset.section;
+      var title = section.querySelector('.sidebar-section-title');
+
+      // Restore saved state (but never collapse a section that has the active nav item)
+      var hasActive = section.querySelector('.sidebar-nav li a.active, .sidebar-subnav li a.active');
+      if (stored[id] && !hasActive) {
+        section.classList.add('collapsed');
+      }
+
+      title.addEventListener('click', function() {
+        section.classList.toggle('collapsed');
+        stored[id] = section.classList.contains('collapsed');
+        try { localStorage.setItem(KEY, JSON.stringify(stored)); } catch(e) {}
+      });
+    });
+  })();
+  </script>
 </body>
 </html>

From f4a92ba45c7b652c5ee0881954c4519717416519 Mon Sep 17 00:00:00 2001
From: Jacob Coffee <jacob@z7x.org>
Date: Thu, 19 Mar 2026 13:14:36 -0500
Subject: [PATCH 2/7] feat: add Purchase Orders & Corporate Invoicing (Phase
 20)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 src/django_program/registration/admin.py      |  69 +++++
 ...eorder_purchaseordercreditnote_and_more.py | 189 +++++++++++++
 src/django_program/registration/models.py     |  10 +
 .../registration/purchase_order.py            | 200 +++++++++++++
 .../registration/services/purchase_orders.py  | 267 ++++++++++++++++++
 5 files changed, 735 insertions(+)
 create mode 100644 src/django_program/registration/migrations/0020_purchaseorder_purchaseordercreditnote_and_more.py
 create mode 100644 src/django_program/registration/purchase_order.py
 create mode 100644 src/django_program/registration/services/purchase_orders.py

diff --git a/src/django_program/registration/admin.py b/src/django_program/registration/admin.py
index eae5f51..41dc025 100644
--- a/src/django_program/registration/admin.py
+++ b/src/django_program/registration/admin.py
@@ -28,6 +28,12 @@
     TicketType,
     Voucher,
 )
+from django_program.registration.purchase_order import (
+    PurchaseOrder,
+    PurchaseOrderCreditNote,
+    PurchaseOrderLineItem,
+    PurchaseOrderPayment,
+)
 from django_program.registration.terminal import TerminalPayment
 
 
@@ -482,3 +488,66 @@ def has_change_permission(self, request: HttpRequest, obj: TerminalPayment | Non
 
     def has_delete_permission(self, request: HttpRequest, obj: TerminalPayment | None = None) -> bool:  # noqa: ARG002, D102
         return False
+
+
+# -- Purchase Order admin -----------------------------------------------------
+
+
+class PurchaseOrderLineItemInline(admin.TabularInline):
+    """Inline display of purchase order line items.
+
+    Line items are pricing snapshots and ``line_total`` is read-only to
+    prevent manual edits that would desynchronize the PO totals.
+    """
+
+    model = PurchaseOrderLineItem
+    extra = 0
+    readonly_fields = ("line_total",)
+
+
+class PurchaseOrderPaymentInline(admin.TabularInline):
+    """Inline display of payments recorded against a purchase order."""
+
+    model = PurchaseOrderPayment
+    extra = 0
+
+
+class PurchaseOrderCreditNoteInline(admin.TabularInline):
+    """Inline display of credit notes issued against a purchase order."""
+
+    model = PurchaseOrderCreditNote
+    extra = 0
+
+
+@admin.register(PurchaseOrder)
+class PurchaseOrderAdmin(admin.ModelAdmin):
+    """Admin interface for managing corporate purchase orders.
+
+    Displays the PO reference, organization, status, and financial summary.
+    Money fields are read-only to prevent manual edits; changes should flow
+    through the payment recording and credit note workflows.
+    """
+
+    list_display = (
+        "reference",
+        "organization_name",
+        "conference",
+        "status",
+        "total",
+        "balance_due_display",
+        "created_at",
+    )
+    list_filter = ("conference", "status")
+    search_fields = ("reference", "organization_name", "contact_email")
+    readonly_fields = ("reference", "subtotal", "total", "balance_due_display", "total_paid_display")
+    inlines = (PurchaseOrderLineItemInline, PurchaseOrderPaymentInline, PurchaseOrderCreditNoteInline)
+
+    @admin.display(description="Balance Due")
+    def balance_due_display(self, obj: PurchaseOrder) -> str:
+        """Render the computed balance due for the list and detail views."""
+        return str(obj.balance_due)
+
+    @admin.display(description="Total Paid")
+    def total_paid_display(self, obj: PurchaseOrder) -> str:
+        """Render the computed total paid for the detail view."""
+        return str(obj.total_paid)
diff --git a/src/django_program/registration/migrations/0020_purchaseorder_purchaseordercreditnote_and_more.py b/src/django_program/registration/migrations/0020_purchaseorder_purchaseordercreditnote_and_more.py
new file mode 100644
index 0000000..2a63af8
--- /dev/null
+++ b/src/django_program/registration/migrations/0020_purchaseorder_purchaseordercreditnote_and_more.py
@@ -0,0 +1,189 @@
+# Generated by Django 5.2.11 on 2026-03-19 18:12
+
+import django.db.models.deletion
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("program_conference", "0009_featureflags_visa_letters_enabled"),
+        ("program_registration", "0019_add_letter_request"),
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name="PurchaseOrder",
+            fields=[
+                ("id", models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name="ID")),
+                ("organization_name", models.CharField(max_length=300)),
+                ("contact_email", models.EmailField(max_length=254)),
+                ("contact_name", models.CharField(max_length=200)),
+                ("billing_address", models.TextField(blank=True, default="")),
+                (
+                    "status",
+                    models.CharField(
+                        choices=[
+                            ("draft", "Draft"),
+                            ("sent", "Sent"),
+                            ("partially_paid", "Partially Paid"),
+                            ("paid", "Paid"),
+                            ("overpaid", "Overpaid"),
+                            ("cancelled", "Cancelled"),
+                        ],
+                        default="draft",
+                        max_length=20,
+                    ),
+                ),
+                ("notes", models.TextField(blank=True, default="")),
+                (
+                    "reference",
+                    models.CharField(help_text='Unique PO reference, e.g. "PO-A1B2C3".', max_length=100, unique=True),
+                ),
+                ("subtotal", models.DecimalField(decimal_places=2, default=0, max_digits=10)),
+                ("total", models.DecimalField(decimal_places=2, default=0, max_digits=10)),
+                ("created_at", models.DateTimeField(auto_now_add=True)),
+                ("updated_at", models.DateTimeField(auto_now=True)),
+                (
+                    "conference",
+                    models.ForeignKey(
+                        on_delete=django.db.models.deletion.CASCADE,
+                        related_name="purchase_orders",
+                        to="program_conference.conference",
+                    ),
+                ),
+                (
+                    "created_by",
+                    models.ForeignKey(
+                        blank=True,
+                        null=True,
+                        on_delete=django.db.models.deletion.SET_NULL,
+                        related_name="created_purchase_orders",
+                        to=settings.AUTH_USER_MODEL,
+                    ),
+                ),
+            ],
+            options={
+                "ordering": ["-created_at"],
+            },
+        ),
+        migrations.CreateModel(
+            name="PurchaseOrderCreditNote",
+            fields=[
+                ("id", models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name="ID")),
+                ("amount", models.DecimalField(decimal_places=2, max_digits=10)),
+                ("reason", models.TextField()),
+                ("created_at", models.DateTimeField(auto_now_add=True)),
+                (
+                    "issued_by",
+                    models.ForeignKey(
+                        blank=True,
+                        null=True,
+                        on_delete=django.db.models.deletion.SET_NULL,
+                        related_name="issued_po_credit_notes",
+                        to=settings.AUTH_USER_MODEL,
+                    ),
+                ),
+                (
+                    "purchase_order",
+                    models.ForeignKey(
+                        on_delete=django.db.models.deletion.CASCADE,
+                        related_name="credit_notes",
+                        to="program_registration.purchaseorder",
+                    ),
+                ),
+            ],
+            options={
+                "ordering": ["-created_at"],
+            },
+        ),
+        migrations.CreateModel(
+            name="PurchaseOrderLineItem",
+            fields=[
+                ("id", models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name="ID")),
+                ("description", models.CharField(max_length=300)),
+                ("quantity", models.PositiveIntegerField(default=1)),
+                ("unit_price", models.DecimalField(decimal_places=2, max_digits=10)),
+                ("line_total", models.DecimalField(decimal_places=2, max_digits=10)),
+                ("created_at", models.DateTimeField(auto_now_add=True)),
+                (
+                    "addon",
+                    models.ForeignKey(
+                        blank=True,
+                        null=True,
+                        on_delete=django.db.models.deletion.SET_NULL,
+                        related_name="purchase_order_line_items",
+                        to="program_registration.addon",
+                    ),
+                ),
+                (
+                    "purchase_order",
+                    models.ForeignKey(
+                        on_delete=django.db.models.deletion.CASCADE,
+                        related_name="line_items",
+                        to="program_registration.purchaseorder",
+                    ),
+                ),
+                (
+                    "ticket_type",
+                    models.ForeignKey(
+                        blank=True,
+                        null=True,
+                        on_delete=django.db.models.deletion.SET_NULL,
+                        related_name="purchase_order_line_items",
+                        to="program_registration.tickettype",
+                    ),
+                ),
+            ],
+            options={
+                "ordering": ["id"],
+            },
+        ),
+        migrations.CreateModel(
+            name="PurchaseOrderPayment",
+            fields=[
+                ("id", models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name="ID")),
+                ("amount", models.DecimalField(decimal_places=2, max_digits=10)),
+                ("reference", models.CharField(blank=True, default="", max_length=200)),
+                (
+                    "method",
+                    models.CharField(
+                        choices=[
+                            ("wire", "Wire Transfer"),
+                            ("ach", "ACH"),
+                            ("check", "Check"),
+                            ("stripe", "Stripe"),
+                            ("other", "Other"),
+                        ],
+                        default="wire",
+                        max_length=20,
+                    ),
+                ),
+                ("payment_date", models.DateField()),
+                ("note", models.TextField(blank=True, default="")),
+                ("created_at", models.DateTimeField(auto_now_add=True)),
+                (
+                    "entered_by",
+                    models.ForeignKey(
+                        blank=True,
+                        null=True,
+                        on_delete=django.db.models.deletion.SET_NULL,
+                        related_name="entered_po_payments",
+                        to=settings.AUTH_USER_MODEL,
+                    ),
+                ),
+                (
+                    "purchase_order",
+                    models.ForeignKey(
+                        on_delete=django.db.models.deletion.CASCADE,
+                        related_name="payments",
+                        to="program_registration.purchaseorder",
+                    ),
+                ),
+            ],
+            options={
+                "ordering": ["-payment_date"],
+            },
+        ),
+    ]
diff --git a/src/django_program/registration/models.py b/src/django_program/registration/models.py
index a25bd36..7813894 100644
--- a/src/django_program/registration/models.py
+++ b/src/django_program/registration/models.py
@@ -695,6 +695,12 @@ def __str__(self) -> str:
     TimeOrStockLimitCondition,
 )
 from django_program.registration.letter import LetterRequest  # noqa: E402
+from django_program.registration.purchase_order import (  # noqa: E402
+    PurchaseOrder,
+    PurchaseOrderCreditNote,
+    PurchaseOrderLineItem,
+    PurchaseOrderPayment,
+)
 from django_program.registration.terminal import TerminalPayment  # noqa: E402
 
 __all__ = [
@@ -718,6 +724,10 @@ def __str__(self) -> str:
     "OrderLineItem",
     "Payment",
     "ProductRedemption",
+    "PurchaseOrder",
+    "PurchaseOrderCreditNote",
+    "PurchaseOrderLineItem",
+    "PurchaseOrderPayment",
     "SpeakerCondition",
     "StripeCustomer",
     "StripeEvent",
diff --git a/src/django_program/registration/purchase_order.py b/src/django_program/registration/purchase_order.py
new file mode 100644
index 0000000..b51a44f
--- /dev/null
+++ b/src/django_program/registration/purchase_order.py
@@ -0,0 +1,200 @@
+"""Purchase order and corporate invoicing models.
+
+Supports offline corporate purchases where organizations pay via wire transfer,
+ACH, check, or other non-card methods. Each purchase order tracks line items,
+partial payments, and credit notes independently of the cart/checkout flow.
+"""
+
+from decimal import Decimal
+
+from django.conf import settings
+from django.db import models
+
+
+class PurchaseOrder(models.Model):
+    """A corporate purchase order for bulk or invoiced ticket purchases.
+
+    Purchase orders exist outside the normal cart/checkout flow and support
+    partial payments over time via wire, ACH, check, or Stripe. The
+    ``balance_due`` property tracks the remaining amount after payments
+    and credit notes.
+    """
+
+    class Status(models.TextChoices):
+        """Lifecycle states for a purchase order."""
+
+        DRAFT = "draft", "Draft"
+        SENT = "sent", "Sent"
+        PARTIALLY_PAID = "partially_paid", "Partially Paid"
+        PAID = "paid", "Paid"
+        OVERPAID = "overpaid", "Overpaid"
+        CANCELLED = "cancelled", "Cancelled"
+
+    conference = models.ForeignKey(
+        "program_conference.Conference",
+        on_delete=models.CASCADE,
+        related_name="purchase_orders",
+    )
+    organization_name = models.CharField(max_length=300)
+    contact_email = models.EmailField()
+    contact_name = models.CharField(max_length=200)
+    billing_address = models.TextField(blank=True, default="")
+    status = models.CharField(
+        max_length=20,
+        choices=Status.choices,
+        default=Status.DRAFT,
+    )
+    notes = models.TextField(blank=True, default="")
+    reference = models.CharField(
+        max_length=100,
+        unique=True,
+        help_text='Unique PO reference, e.g. "PO-A1B2C3".',
+    )
+    subtotal = models.DecimalField(max_digits=10, decimal_places=2, default=0)
+    total = models.DecimalField(max_digits=10, decimal_places=2, default=0)
+    created_by = models.ForeignKey(
+        settings.AUTH_USER_MODEL,
+        on_delete=models.SET_NULL,
+        null=True,
+        blank=True,
+        related_name="created_purchase_orders",
+    )
+    created_at = models.DateTimeField(auto_now_add=True)
+    updated_at = models.DateTimeField(auto_now=True)
+
+    class Meta:
+        ordering = ["-created_at"]
+
+    def __str__(self) -> str:
+        return f"{self.reference} ({self.status})"
+
+    @property
+    def total_paid(self) -> Decimal:
+        """Return the sum of all recorded payment amounts."""
+        return self.payments.aggregate(total=models.Sum("amount"))["total"] or Decimal("0.00")
+
+    @property
+    def total_credited(self) -> Decimal:
+        """Return the sum of all credit note amounts."""
+        return self.credit_notes.aggregate(total=models.Sum("amount"))["total"] or Decimal("0.00")
+
+    @property
+    def balance_due(self) -> Decimal:
+        """Return the outstanding balance after payments and credit notes."""
+        return self.total - self.total_paid - self.total_credited
+
+
+class PurchaseOrderLineItem(models.Model):
+    """A single line item on a purchase order.
+
+    Each line references an optional ticket type or add-on for traceability,
+    but the description and pricing are snapshotted at creation time.
+    """
+
+    purchase_order = models.ForeignKey(
+        PurchaseOrder,
+        on_delete=models.CASCADE,
+        related_name="line_items",
+    )
+    description = models.CharField(max_length=300)
+    quantity = models.PositiveIntegerField(default=1)
+    unit_price = models.DecimalField(max_digits=10, decimal_places=2)
+    line_total = models.DecimalField(max_digits=10, decimal_places=2)
+    ticket_type = models.ForeignKey(
+        "program_registration.TicketType",
+        on_delete=models.SET_NULL,
+        null=True,
+        blank=True,
+        related_name="purchase_order_line_items",
+    )
+    addon = models.ForeignKey(
+        "program_registration.AddOn",
+        on_delete=models.SET_NULL,
+        null=True,
+        blank=True,
+        related_name="purchase_order_line_items",
+    )
+    created_at = models.DateTimeField(auto_now_add=True)
+
+    class Meta:
+        ordering = ["id"]
+
+    def __str__(self) -> str:
+        return f"{self.quantity}x {self.description}"
+
+
+class PurchaseOrderPayment(models.Model):
+    """A payment recorded against a purchase order.
+
+    Tracks individual payments received via wire transfer, ACH, check,
+    Stripe, or other methods. Multiple payments can be recorded as
+    partial payments arrive.
+    """
+
+    class Method(models.TextChoices):
+        """Supported payment methods for purchase orders."""
+
+        WIRE = "wire", "Wire Transfer"
+        ACH = "ach", "ACH"
+        CHECK = "check", "Check"
+        STRIPE = "stripe", "Stripe"
+        OTHER = "other", "Other"
+
+    purchase_order = models.ForeignKey(
+        PurchaseOrder,
+        on_delete=models.CASCADE,
+        related_name="payments",
+    )
+    amount = models.DecimalField(max_digits=10, decimal_places=2)
+    reference = models.CharField(max_length=200, blank=True, default="")
+    method = models.CharField(
+        max_length=20,
+        choices=Method.choices,
+        default=Method.WIRE,
+    )
+    entered_by = models.ForeignKey(
+        settings.AUTH_USER_MODEL,
+        on_delete=models.SET_NULL,
+        null=True,
+        blank=True,
+        related_name="entered_po_payments",
+    )
+    payment_date = models.DateField()
+    note = models.TextField(blank=True, default="")
+    created_at = models.DateTimeField(auto_now_add=True)
+
+    class Meta:
+        ordering = ["-payment_date"]
+
+    def __str__(self) -> str:
+        return f"{self.get_method_display()} {self.amount} on {self.payment_date}"
+
+
+class PurchaseOrderCreditNote(models.Model):
+    """A credit note issued against a purchase order.
+
+    Reduces the effective balance due on the purchase order. Used for
+    adjustments, corrections, or partial cancellations.
+    """
+
+    purchase_order = models.ForeignKey(
+        PurchaseOrder,
+        on_delete=models.CASCADE,
+        related_name="credit_notes",
+    )
+    amount = models.DecimalField(max_digits=10, decimal_places=2)
+    reason = models.TextField()
+    issued_by = models.ForeignKey(
+        settings.AUTH_USER_MODEL,
+        on_delete=models.SET_NULL,
+        null=True,
+        blank=True,
+        related_name="issued_po_credit_notes",
+    )
+    created_at = models.DateTimeField(auto_now_add=True)
+
+    class Meta:
+        ordering = ["-created_at"]
+
+    def __str__(self) -> str:
+        return f"Credit {self.amount} — {str(self.reason)[:50]}"
diff --git a/src/django_program/registration/services/purchase_orders.py b/src/django_program/registration/services/purchase_orders.py
new file mode 100644
index 0000000..b7c3092
--- /dev/null
+++ b/src/django_program/registration/services/purchase_orders.py
@@ -0,0 +1,267 @@
+"""Service layer for purchase order lifecycle management.
+
+Handles PO creation, payment recording, credit note issuance, status
+transitions, and cancellation. All state-mutating functions use atomic
+transactions to maintain consistency.
+"""
+
+import logging
+import secrets
+import string
+from decimal import Decimal
+from typing import TYPE_CHECKING
+
+from django.db import transaction
+
+from django_program.registration.purchase_order import (
+    PurchaseOrder,
+    PurchaseOrderCreditNote,
+    PurchaseOrderLineItem,
+    PurchaseOrderPayment,
+)
+
+if TYPE_CHECKING:
+    import datetime
+
+    from django.contrib.auth.models import AbstractBaseUser
+
+    from django_program.conference.models import Conference
+
+logger = logging.getLogger(__name__)
+
+_PO_REFERENCE_LENGTH = 6
+_PO_REFERENCE_PREFIX = "PO"
+_MAX_REFERENCE_ATTEMPTS = 10
+
+
+def generate_po_reference() -> str:
+    """Generate a unique PO reference like ``PO-A1B2C3``.
+
+    Uses cryptographically random alphanumeric characters. Retries on
+    collision up to a fixed limit.
+
+    Returns:
+        A unique reference string.
+
+    Raises:
+        RuntimeError: If a unique reference cannot be generated after
+            multiple attempts.
+    """
+    chars = string.ascii_uppercase + string.digits
+    for _ in range(_MAX_REFERENCE_ATTEMPTS):
+        suffix = "".join(secrets.choice(chars) for _ in range(_PO_REFERENCE_LENGTH))
+        ref = f"{_PO_REFERENCE_PREFIX}-{suffix}"
+        if not PurchaseOrder.objects.filter(reference=ref).exists():
+            return ref
+    msg = "Could not generate a unique PO reference after multiple attempts"
+    raise RuntimeError(msg)
+
+
+LineItemData = dict[str, object]
+
+
+@transaction.atomic
+def create_purchase_order(  # noqa: PLR0913
+    *,
+    conference: Conference,
+    organization_name: str,
+    contact_email: str,
+    contact_name: str,
+    billing_address: str = "",
+    line_items: list[LineItemData],
+    notes: str = "",
+    created_by: AbstractBaseUser | None = None,
+) -> PurchaseOrder:
+    """Create a purchase order with line items and computed totals.
+
+    Each entry in ``line_items`` should be a dict with keys:
+    ``description``, ``quantity``, ``unit_price``, and optionally
+    ``ticket_type`` and ``addon`` (model instances or None).
+
+    Args:
+        conference: The conference this PO belongs to.
+        organization_name: Name of the purchasing organization.
+        contact_email: Primary contact email address.
+        contact_name: Primary contact person name.
+        billing_address: Optional billing address text.
+        line_items: List of line item dicts to create.
+        notes: Optional internal notes.
+        created_by: The staff user creating the PO.
+
+    Returns:
+        The newly created PurchaseOrder with line items.
+
+    Raises:
+        RuntimeError: If a unique reference cannot be generated.
+        IntegrityError: On reference collision (extremely unlikely).
+    """
+    reference = generate_po_reference()
+
+    po = PurchaseOrder.objects.create(
+        conference=conference,
+        organization_name=organization_name,
+        contact_email=contact_email,
+        contact_name=contact_name,
+        billing_address=billing_address,
+        status=PurchaseOrder.Status.DRAFT,
+        notes=notes,
+        reference=reference,
+        created_by=created_by,
+    )
+
+    subtotal = Decimal("0.00")
+    for item_data in line_items:
+        quantity = int(item_data.get("quantity", 1))
+        unit_price = Decimal(str(item_data["unit_price"]))
+        line_total = unit_price * quantity
+        subtotal += line_total
+
+        PurchaseOrderLineItem.objects.create(
+            purchase_order=po,
+            description=str(item_data["description"]),
+            quantity=quantity,
+            unit_price=unit_price,
+            line_total=line_total,
+            ticket_type=item_data.get("ticket_type"),
+            addon=item_data.get("addon"),
+        )
+
+    po.subtotal = subtotal
+    po.total = subtotal
+    po.save(update_fields=["subtotal", "total", "updated_at"])
+
+    logger.info("Created purchase order %s for %s", reference, organization_name)
+    return po
+
+
+@transaction.atomic
+def record_payment(  # noqa: PLR0913
+    purchase_order: PurchaseOrder,
+    *,
+    amount: Decimal,
+    method: str,
+    reference: str = "",
+    payment_date: datetime.date,
+    entered_by: AbstractBaseUser | None = None,
+    note: str = "",
+) -> PurchaseOrderPayment:
+    """Record a payment against a purchase order and update its status.
+
+    Args:
+        purchase_order: The PO to record payment against.
+        amount: Payment amount (must be positive).
+        method: Payment method (one of PurchaseOrderPayment.Method values).
+        reference: Optional external reference (e.g. wire transfer ID).
+        payment_date: Date the payment was received.
+        entered_by: Staff user recording the payment.
+        note: Optional note about the payment.
+
+    Returns:
+        The newly created PurchaseOrderPayment.
+    """
+    payment = PurchaseOrderPayment.objects.create(
+        purchase_order=purchase_order,
+        amount=amount,
+        method=method,
+        reference=reference,
+        payment_date=payment_date,
+        entered_by=entered_by,
+        note=note,
+    )
+
+    update_po_status(purchase_order)
+
+    logger.info(
+        "Recorded %s payment of %s for PO %s",
+        method,
+        amount,
+        purchase_order.reference,
+    )
+    return payment
+
+
+@transaction.atomic
+def issue_credit_note(
+    purchase_order: PurchaseOrder,
+    *,
+    amount: Decimal,
+    reason: str,
+    issued_by: AbstractBaseUser | None = None,
+) -> PurchaseOrderCreditNote:
+    """Issue a credit note against a purchase order and update its status.
+
+    Args:
+        purchase_order: The PO to issue a credit note against.
+        amount: Credit note amount (must be positive).
+        reason: Explanation for the credit.
+        issued_by: Staff user issuing the credit note.
+
+    Returns:
+        The newly created PurchaseOrderCreditNote.
+    """
+    credit_note = PurchaseOrderCreditNote.objects.create(
+        purchase_order=purchase_order,
+        amount=amount,
+        reason=reason,
+        issued_by=issued_by,
+    )
+
+    update_po_status(purchase_order)
+
+    logger.info(
+        "Issued credit note of %s for PO %s: %s",
+        amount,
+        purchase_order.reference,
+        reason[:80],
+    )
+    return credit_note
+
+
+def update_po_status(purchase_order: PurchaseOrder) -> None:
+    """Recompute and save the PO status based on payments and credits.
+
+    Status transitions:
+    - ``draft`` remains if no payments and status is draft
+    - ``paid`` when balance_due is exactly zero
+    - ``overpaid`` when balance_due is negative
+    - ``partially_paid`` when some payments exist but balance remains
+    - ``sent`` when no payments exist and status is not draft
+
+    Args:
+        purchase_order: The PO whose status should be recomputed.
+    """
+    if purchase_order.status == PurchaseOrder.Status.CANCELLED:
+        return
+
+    purchase_order.refresh_from_db()
+    balance = purchase_order.balance_due
+    total_paid = purchase_order.total_paid
+
+    if balance == Decimal("0.00") and total_paid > Decimal("0.00"):
+        new_status = PurchaseOrder.Status.PAID
+    elif balance < Decimal("0.00"):
+        new_status = PurchaseOrder.Status.OVERPAID
+    elif total_paid > Decimal("0.00"):
+        new_status = PurchaseOrder.Status.PARTIALLY_PAID
+    elif purchase_order.status == PurchaseOrder.Status.DRAFT:
+        new_status = PurchaseOrder.Status.DRAFT
+    else:
+        new_status = PurchaseOrder.Status.SENT
+
+    if new_status != purchase_order.status:
+        purchase_order.status = new_status
+        purchase_order.save(update_fields=["status", "updated_at"])
+
+
+def cancel_purchase_order(purchase_order: PurchaseOrder) -> None:
+    """Cancel a purchase order.
+
+    Sets the status to CANCELLED. Does not delete any associated payment
+    or credit note records for audit purposes.
+
+    Args:
+        purchase_order: The PO to cancel.
+    """
+    purchase_order.status = PurchaseOrder.Status.CANCELLED
+    purchase_order.save(update_fields=["status", "updated_at"])
+    logger.info("Cancelled purchase order %s", purchase_order.reference)

From c910fe10c96d3546b2a506b7185f0dad2dbcaf9d Mon Sep 17 00:00:00 2001
From: Jacob Coffee <jacob@z7x.org>
Date: Thu, 19 Mar 2026 13:22:27 -0500
Subject: [PATCH 3/7] feat: add PO management UI, seed data, and tests (Phase
 20)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 examples/seed.py                              | 420 +++++++++++--
 .../templates/django_program/manage/base.html |   5 +
 .../manage/purchase_order_detail.html         | 258 ++++++++
 .../manage/purchase_order_form.html           | 242 ++++++++
 .../manage/purchase_order_list.html           |  90 +++
 src/django_program/manage/urls.py             |   2 +
 .../manage/urls_purchase_orders.py            |  25 +
 .../manage/views_purchase_orders.py           | 327 ++++++++++
 .../test_registration/test_purchase_orders.py | 585 ++++++++++++++++++
 9 files changed, 1892 insertions(+), 62 deletions(-)
 create mode 100644 src/django_program/manage/templates/django_program/manage/purchase_order_detail.html
 create mode 100644 src/django_program/manage/templates/django_program/manage/purchase_order_form.html
 create mode 100644 src/django_program/manage/templates/django_program/manage/purchase_order_list.html
 create mode 100644 src/django_program/manage/urls_purchase_orders.py
 create mode 100644 src/django_program/manage/views_purchase_orders.py
 create mode 100644 tests/test_registration/test_purchase_orders.py

diff --git a/examples/seed.py b/examples/seed.py
index 92570d1..4f79e89 100644
--- a/examples/seed.py
+++ b/examples/seed.py
@@ -51,6 +51,17 @@
     TicketType,
     Voucher,
 )
+from django_program.registration.purchase_order import (
+    PurchaseOrder,
+    PurchaseOrderCreditNote,
+    PurchaseOrderPayment,
+)
+from django_program.registration.services.purchase_orders import (
+    cancel_purchase_order,
+    create_purchase_order,
+    issue_credit_note,
+    record_payment,
+)
 from django_program.sponsors.models import BulkPurchase, BulkPurchaseVoucher, Sponsor, SponsorBenefit, SponsorLevel
 
 User = get_user_model()
@@ -179,6 +190,7 @@ def run(self) -> None:
         self._create_more_carts(conference, users, ticket_types, addons)
         self._create_bulk_purchases(conference, sponsors, ticket_types, addons, users)
         self._create_letter_requests(conference, users)
+        self._create_purchase_orders(conference, users, ticket_types, addons)
         self._create_badges(conference)
 
         # Set up permission groups
@@ -212,6 +224,7 @@ def _print_summary(
         n_grants = TravelGrant.objects.filter(conference=conference).count()
         n_surveys = Survey.objects.filter(conference=conference).count()
         n_bulk = BulkPurchase.objects.filter(conference=conference).count()
+        n_pos = PurchaseOrder.objects.filter(conference=conference).count()
         n_letters = LetterRequest.objects.filter(conference=conference).count()
         n_sponsors = Sponsor.objects.filter(conference=conference).count()
         n_badge_templates = BadgeTemplate.objects.filter(conference=conference).count()
@@ -249,6 +262,7 @@ def _print_summary(
         print(f"\n  {'--- Finance ---':{W}}")
         print(f"  {'Sponsors':{W}} {n_sponsors}")
         print(f"  {'Bulk purchases':{W}} {n_bulk}")
+        print(f"  {'Purchase orders':{W}} {n_pos}")
         print(f"  {'Expenses':{W}} {n_expenses}")
         print(f"  {'Travel grants':{W}} {n_grants}")
 
@@ -1557,6 +1571,334 @@ def _create_bulk_purchases(
                 },
             )
 
+    def _create_purchase_orders(
+        self,
+        conference: Conference,
+        _users: list,
+        ticket_types: list[TicketType],
+        addons: list[AddOn],
+    ) -> None:
+        """Create purchase orders across all lifecycle states."""
+        if PurchaseOrder.objects.filter(conference=conference).exists():
+            print("  Purchase orders already exist, skipping.")
+            return
+
+        admin = User.objects.filter(is_superuser=True).first()
+        today = datetime.datetime.now(tz=datetime.UTC).date()
+
+        # Find a corporate ticket and a useful addon
+        corp_ticket = next((t for t in ticket_types if "corporate" in str(t.slug).lower()), ticket_types[0])
+        workshop_addon = next(
+            (a for a in addons if str(a.slug) in ("workshop", "tutorial")),
+            addons[0] if addons else None,
+        )
+        tshirt_addon = next(
+            (a for a in addons if "shirt" in str(a.slug).lower()),
+            addons[1] if len(addons) > 1 else None,
+        )
+        tutorial_addon = next(
+            (a for a in addons if str(a.slug) == "tutorial"),
+            addons[0] if addons else None,
+        )
+
+        corp_price = corp_ticket.price
+
+        # 1. Draft PO — Acme Corp, 10x Corporate, no payments
+        print("  Creating purchase orders...")
+        po_draft = create_purchase_order(
+            conference=conference,
+            organization_name="Acme Corp",
+            contact_email="procurement@acmecorp.example.com",
+            contact_name="Janet Reeves",
+            billing_address="100 Innovation Drive, Suite 400\nSan Francisco, CA 94105",
+            line_items=[
+                {
+                    "description": str(corp_ticket.name),
+                    "quantity": 10,
+                    "unit_price": corp_price,
+                    "ticket_type": corp_ticket,
+                },
+            ],
+            notes="Awaiting internal budget approval before sending.",
+            created_by=admin,
+        )
+        print(f"    {po_draft.reference}: Draft — Acme Corp (10x {corp_ticket.name})")
+
+        # 2. Sent/awaiting payment — TechStart Inc, 5x Corporate + 5x Workshop
+        po_sent = create_purchase_order(
+            conference=conference,
+            organization_name="TechStart Inc",
+            contact_email="accounting@techstart.example.com",
+            contact_name="Marcus Chen",
+            billing_address="2200 Startup Blvd\nAustin, TX 78701",
+            line_items=[
+                {
+                    "description": str(corp_ticket.name),
+                    "quantity": 5,
+                    "unit_price": corp_price,
+                    "ticket_type": corp_ticket,
+                },
+            ]
+            + (
+                [
+                    {
+                        "description": str(workshop_addon.name),
+                        "quantity": 5,
+                        "unit_price": workshop_addon.price,
+                        "addon": workshop_addon,
+                    },
+                ]
+                if workshop_addon
+                else []
+            ),
+            notes="Invoice sent via email on request. Net 30 terms.",
+            created_by=admin,
+        )
+        po_sent.status = PurchaseOrder.Status.SENT
+        po_sent.save(update_fields=["status", "updated_at"])
+        print(f"    {po_sent.reference}: Sent — TechStart Inc (5x tickets + 5x addons)")
+
+        # 3. Partially paid — Global Systems Ltd, 20x Corporate, ~60% paid
+        po_partial = create_purchase_order(
+            conference=conference,
+            organization_name="Global Systems Ltd",
+            contact_email="finance@globalsystems.example.com",
+            contact_name="Priya Kapoor",
+            billing_address="45 Enterprise Way\nChicago, IL 60601",
+            line_items=[
+                {
+                    "description": str(corp_ticket.name),
+                    "quantity": 20,
+                    "unit_price": corp_price,
+                    "ticket_type": corp_ticket,
+                },
+            ],
+            notes="First wire received. Remainder expected by end of month.",
+            created_by=admin,
+        )
+        partial_amount = (po_partial.total * Decimal("0.6")).quantize(Decimal("0.01"))
+        record_payment(
+            po_partial,
+            amount=partial_amount,
+            method=PurchaseOrderPayment.Method.WIRE,
+            reference="WIRE-GS-20270301",
+            payment_date=today - datetime.timedelta(days=12),
+            entered_by=admin,
+            note="First installment via international wire.",
+        )
+        print(
+            f"    {po_partial.reference}: Partially paid — Global Systems Ltd"
+            f" (20x, {partial_amount} of {po_partial.total})"
+        )
+
+        # 4. Fully paid — DataFlow Analytics, 8x Corporate + 8x T-shirt, two payments
+        line_items_df: list[dict[str, object]] = [
+            {
+                "description": str(corp_ticket.name),
+                "quantity": 8,
+                "unit_price": corp_price,
+                "ticket_type": corp_ticket,
+            },
+        ]
+        if tshirt_addon:
+            line_items_df.append(
+                {
+                    "description": str(tshirt_addon.name),
+                    "quantity": 8,
+                    "unit_price": tshirt_addon.price,
+                    "addon": tshirt_addon,
+                },
+            )
+        po_paid = create_purchase_order(
+            conference=conference,
+            organization_name="DataFlow Analytics",
+            contact_email="ap@dataflow.example.com",
+            contact_name="Tomás Rivera",
+            billing_address="800 Data Center Pkwy\nSeattle, WA 98101",
+            line_items=line_items_df,
+            notes="Paid in full across two installments.",
+            created_by=admin,
+        )
+        first_payment = (po_paid.total * Decimal("0.7")).quantize(Decimal("0.01"))
+        second_payment = po_paid.total - first_payment
+        record_payment(
+            po_paid,
+            amount=first_payment,
+            method=PurchaseOrderPayment.Method.WIRE,
+            reference="WIRE-DF-20270215",
+            payment_date=today - datetime.timedelta(days=25),
+            entered_by=admin,
+            note="Initial wire transfer.",
+        )
+        record_payment(
+            po_paid,
+            amount=second_payment,
+            method=PurchaseOrderPayment.Method.ACH,
+            reference="ACH-DF-20270228",
+            payment_date=today - datetime.timedelta(days=10),
+            entered_by=admin,
+            note="Final ACH payment.",
+        )
+        print(f"    {po_paid.reference}: Paid — DataFlow Analytics (8x tickets + 8x addons)")
+
+        # 5. Overpaid — Innovation Hub Co, 3x Corporate, payment exceeds total by $50
+        po_over = create_purchase_order(
+            conference=conference,
+            organization_name="Innovation Hub Co",
+            contact_email="billing@innovationhub.example.com",
+            contact_name="Sana Al-Rashid",
+            billing_address="350 Catalyst Lane\nBoston, MA 02101",
+            line_items=[
+                {
+                    "description": str(corp_ticket.name),
+                    "quantity": 3,
+                    "unit_price": corp_price,
+                    "ticket_type": corp_ticket,
+                },
+            ],
+            notes="Overpayment of $50 — refund or credit pending.",
+            created_by=admin,
+        )
+        po_over.status = PurchaseOrder.Status.SENT
+        po_over.save(update_fields=["status", "updated_at"])
+        record_payment(
+            po_over,
+            amount=po_over.total + Decimal("50.00"),
+            method=PurchaseOrderPayment.Method.WIRE,
+            reference="WIRE-IH-20270305",
+            payment_date=today - datetime.timedelta(days=8),
+            entered_by=admin,
+            note="Wire transfer exceeded invoice total.",
+        )
+        print(f"    {po_over.reference}: Overpaid — Innovation Hub Co (3x, +$50 over)")
+
+        # 6. Cancelled — CloudNine Enterprises, 15x Corporate
+        po_cancelled = create_purchase_order(
+            conference=conference,
+            organization_name="CloudNine Enterprises",
+            contact_email="events@cloudnine.example.com",
+            contact_name="Derek O'Sullivan",
+            billing_address="900 Nimbus Ave\nDenver, CO 80202",
+            line_items=[
+                {
+                    "description": str(corp_ticket.name),
+                    "quantity": 15,
+                    "unit_price": corp_price,
+                    "ticket_type": corp_ticket,
+                },
+            ],
+            notes="Cancelled — company withdrew conference sponsorship.",
+            created_by=admin,
+        )
+        cancel_purchase_order(po_cancelled)
+        print(f"    {po_cancelled.reference}: Cancelled — CloudNine Enterprises (15x)")
+
+        # 7. PO with credit note — Digital Frontier Inc, 12x Corporate, paid, then credit for 2 tickets
+        po_credit = create_purchase_order(
+            conference=conference,
+            organization_name="Digital Frontier Inc",
+            contact_email="finance@digitalfrontier.example.com",
+            contact_name="Elena Vasquez",
+            billing_address="1500 Binary Blvd\nPortland, OR 97201",
+            line_items=[
+                {
+                    "description": str(corp_ticket.name),
+                    "quantity": 12,
+                    "unit_price": corp_price,
+                    "ticket_type": corp_ticket,
+                },
+            ],
+            notes="2 attendees cancelled, credit note issued for their tickets.",
+            created_by=admin,
+        )
+        po_credit.status = PurchaseOrder.Status.SENT
+        po_credit.save(update_fields=["status", "updated_at"])
+        record_payment(
+            po_credit,
+            amount=po_credit.total,
+            method=PurchaseOrderPayment.Method.ACH,
+            reference="ACH-DF-20270220",
+            payment_date=today - datetime.timedelta(days=20),
+            entered_by=admin,
+            note="Full payment received.",
+        )
+        credit_amount = corp_price * 2
+        issue_credit_note(
+            po_credit,
+            amount=credit_amount,
+            reason="2 attendees unable to attend — tickets cancelled per organization request.",
+            issued_by=admin,
+        )
+        print(f"    {po_credit.reference}: Paid + credit note — Digital Frontier Inc (12x, credit for 2)")
+
+        # 8. Multi-payment PO — Enterprise Solutions Group, 25x Corporate + 10x Tutorial, 3 payments
+        line_items_es: list[dict[str, object]] = [
+            {
+                "description": str(corp_ticket.name),
+                "quantity": 25,
+                "unit_price": corp_price,
+                "ticket_type": corp_ticket,
+            },
+        ]
+        if tutorial_addon:
+            line_items_es.append(
+                {
+                    "description": str(tutorial_addon.name),
+                    "quantity": 10,
+                    "unit_price": tutorial_addon.price,
+                    "addon": tutorial_addon,
+                },
+            )
+        po_multi = create_purchase_order(
+            conference=conference,
+            organization_name="Enterprise Solutions Group",
+            contact_email="accounts@enterprisesolutions.example.com",
+            contact_name="Wesley Park",
+            billing_address="7000 Commerce Tower, 12th Floor\nNew York, NY 10001",
+            line_items=line_items_es,
+            notes="Large corporate deal — staggered payments per contract terms.",
+            created_by=admin,
+        )
+        po_multi.status = PurchaseOrder.Status.SENT
+        po_multi.save(update_fields=["status", "updated_at"])
+        remaining = po_multi.total
+        payment_1 = (remaining * Decimal("0.4")).quantize(Decimal("0.01"))
+        payment_2 = (remaining * Decimal("0.35")).quantize(Decimal("0.01"))
+        payment_3 = remaining - payment_1 - payment_2
+        record_payment(
+            po_multi,
+            amount=payment_1,
+            method=PurchaseOrderPayment.Method.CHECK,
+            reference="CHK-ES-10042",
+            payment_date=today - datetime.timedelta(days=30),
+            entered_by=admin,
+            note="First installment — check received.",
+        )
+        record_payment(
+            po_multi,
+            amount=payment_2,
+            method=PurchaseOrderPayment.Method.WIRE,
+            reference="WIRE-ES-20270301",
+            payment_date=today - datetime.timedelta(days=15),
+            entered_by=admin,
+            note="Second installment — wire transfer.",
+        )
+        record_payment(
+            po_multi,
+            amount=payment_3,
+            method=PurchaseOrderPayment.Method.ACH,
+            reference="ACH-ES-20270310",
+            payment_date=today - datetime.timedelta(days=5),
+            entered_by=admin,
+            note="Final installment — ACH.",
+        )
+        print(f"    {po_multi.reference}: Paid (3 payments) — Enterprise Solutions Group (25x tickets + 10x addons)")
+
+        n_pos = PurchaseOrder.objects.filter(conference=conference).count()
+        n_payments = PurchaseOrderPayment.objects.filter(purchase_order__conference=conference).count()
+        n_credits = PurchaseOrderCreditNote.objects.filter(purchase_order__conference=conference).count()
+        print(f"  Created {n_pos} purchase orders, {n_payments} payments, {n_credits} credit notes.")
+
     def _create_letter_requests(self, conference: Conference, users: list) -> None:
         """Create visa invitation letter requests across various workflow statuses."""
         from django_program.registration.services.letters import generate_invitation_letter
@@ -1728,69 +2070,23 @@ def _create_badges(self, conference: Conference) -> None:
         if BadgeTemplate.objects.filter(conference=conference).exists():
             return
 
-        # Template definitions: (name, slug, is_default, accent, bg, text, show_email,
-        #                        show_company, show_qr, banner_pos)
+        # Each template varies by accent color, which fields are visible, and
+        # banner position so the badge list / preview shows realistic variety.
+        #
+        # (name, slug, is_default, accent, bg, text,
+        #  show_email, show_company, show_qr, banner_pos)
+        BPos = BadgeTemplate.BannerPosition
         template_defs = [
-            (
-                "Default Badge",
-                "default",
-                True,
-                "#4338CA",
-                "#FFFFFF",
-                "#000000",
-                False,
-                False,
-                True,
-                BadgeTemplate.BannerPosition.BELOW_HEADER,
-            ),
-            (
-                "Speaker Badge",
-                "speaker",
-                False,
-                "#DC2626",
-                "#FEF2F2",
-                "#1F2937",
-                True,
-                True,
-                True,
-                BadgeTemplate.BannerPosition.ABOVE_NAME,
-            ),
-            (
-                "Staff Badge",
-                "staff",
-                False,
-                "#059669",
-                "#F0FDF4",
-                "#1F2937",
-                True,
-                False,
-                True,
-                BadgeTemplate.BannerPosition.BELOW_NAME,
-            ),
-            (
-                "Sponsor Badge",
-                "sponsor",
-                False,
-                "#D97706",
-                "#FFFBEB",
-                "#1F2937",
-                True,
-                True,
-                True,
-                BadgeTemplate.BannerPosition.BOTTOM,
-            ),
-            (
-                "Press Badge",
-                "press",
-                False,
-                "#7C3AED",
-                "#F5F3FF",
-                "#1F2937",
-                False,
-                True,
-                False,
-                BadgeTemplate.BannerPosition.BELOW_HEADER,
-            ),
+            # Attendee — clean white, indigo accent, name + QR only
+            ("Default Badge", "default", True, "#4338CA", "#FFFFFF", "#000000", False, False, True, BPos.BELOW_HEADER),
+            # Speaker — white, red accent, show company & email
+            ("Speaker Badge", "speaker", False, "#B91C1C", "#FFFFFF", "#111827", True, True, True, BPos.BELOW_HEADER),
+            # Staff — white, emerald accent, no company/email
+            ("Staff Badge", "staff", False, "#047857", "#FFFFFF", "#111827", False, False, True, BPos.BELOW_HEADER),
+            # Sponsor — white, amber accent, show company
+            ("Sponsor Badge", "sponsor", False, "#B45309", "#FFFFFF", "#111827", False, True, True, BPos.BELOW_HEADER),
+            # Press — white, purple accent, show company, no QR
+            ("Press Badge", "press", False, "#6D28D9", "#FFFFFF", "#111827", False, True, False, BPos.BELOW_HEADER),
         ]
 
         templates: dict[str, BadgeTemplate] = {}
diff --git a/src/django_program/manage/templates/django_program/manage/base.html b/src/django_program/manage/templates/django_program/manage/base.html
index 870783c..288d4b6 100644
--- a/src/django_program/manage/templates/django_program/manage/base.html
+++ b/src/django_program/manage/templates/django_program/manage/base.html
@@ -1209,6 +1209,11 @@
               <span class="sidebar-nav-icon"><svg width="16" height="16" fill="none" stroke="currentColor" stroke-width="1.5"><path d="M2 14h12M4 10h2v4H4zM7 7h2v7H7zM10 4h2v10h-2z"/></svg></span> Financial
             </a>
           </li>
+          <li>
+            <a href="{% url 'manage:purchase-order-list' conference.slug %}" class="{% if active_nav == 'purchase-orders' %}active{% endif %}">
+              <span class="sidebar-nav-icon"><svg width="16" height="16" fill="none" stroke="currentColor" stroke-width="1.5"><path d="M3 1.5h10v13H3z"/><path d="M5.5 4.5h5M5.5 7h5M5.5 9.5h3"/><path d="M7 12.5h2"/></svg></span> Purchase Orders
+            </a>
+          </li>
           <li>
             <a href="{% url 'manage:expense-list' conference.slug %}" class="{% if active_nav == 'expenses' %}active{% endif %}">
               <span class="sidebar-nav-icon"><svg width="16" height="16" fill="none" stroke="currentColor" stroke-width="1.5"><path d="M4 2h8v12H4z"/><path d="M6 5h4M6 7.5h4M6 10h2.5"/><path d="M2 4v10h10"/></svg></span> Expenses
diff --git a/src/django_program/manage/templates/django_program/manage/purchase_order_detail.html b/src/django_program/manage/templates/django_program/manage/purchase_order_detail.html
new file mode 100644
index 0000000..0b4921b
--- /dev/null
+++ b/src/django_program/manage/templates/django_program/manage/purchase_order_detail.html
@@ -0,0 +1,258 @@
+{% extends "django_program/manage/base.html" %}
+
+{% block title %}{{ purchase_order.reference }}{% endblock %}
+
+{% block breadcrumb %}
+<nav class="breadcrumb" aria-label="Breadcrumb">
+  <a href="{% url 'manage:dashboard' conference.slug %}">Dashboard</a>
+  <span class="breadcrumb-separator"></span>
+  <a href="{% url 'manage:purchase-order-list' conference.slug %}">Purchase Orders</a>
+  <span class="breadcrumb-separator"></span>
+  <span>{{ purchase_order.reference }}</span>
+</nav>
+{% endblock %}
+
+{% block page_title %}
+<h1>{{ purchase_order.reference }}
+  {% if purchase_order.status == "draft" %}
+  <span class="badge badge--other" style="vertical-align: middle; font-size: 0.7rem;">Draft</span>
+  {% elif purchase_order.status == "sent" %}
+  <span class="badge badge--accepted" style="vertical-align: middle; font-size: 0.7rem;">Sent</span>
+  {% elif purchase_order.status == "partially_paid" %}
+  <span class="badge badge--warning" style="vertical-align: middle; font-size: 0.7rem;">Partially Paid</span>
+  {% elif purchase_order.status == "paid" %}
+  <span class="badge badge--active" style="vertical-align: middle; font-size: 0.7rem;">Paid</span>
+  {% elif purchase_order.status == "overpaid" %}
+  <span class="badge badge--synced" style="vertical-align: middle; font-size: 0.7rem;">Overpaid</span>
+  {% elif purchase_order.status == "cancelled" %}
+  <span class="badge badge--inactive" style="vertical-align: middle; font-size: 0.7rem;">Cancelled</span>
+  {% endif %}
+</h1>
+<p>{{ purchase_order.organization_name }}</p>
+{% endblock %}
+
+{% block content %}
+{# ── Contact & Billing Info ── #}
+<div class="info-grid" style="margin-bottom: 2rem;">
+  <div class="info-item">
+    <div class="info-item-label">Organization</div>
+    <div class="info-item-value">{{ purchase_order.organization_name }}</div>
+  </div>
+  <div class="info-item">
+    <div class="info-item-label">Contact Name</div>
+    <div class="info-item-value">{% if purchase_order.contact_name %}{{ purchase_order.contact_name }}{% else %}--{% endif %}</div>
+  </div>
+  <div class="info-item">
+    <div class="info-item-label">Contact Email</div>
+    <div class="info-item-value"><a href="mailto:{{ purchase_order.contact_email }}">{{ purchase_order.contact_email }}</a></div>
+  </div>
+  <div class="info-item">
+    <div class="info-item-label">Billing Address</div>
+    <div class="info-item-value">{% if purchase_order.billing_address %}{{ purchase_order.billing_address|linebreaksbr }}{% else %}--{% endif %}</div>
+  </div>
+  <div class="info-item">
+    <div class="info-item-label">Created By</div>
+    <div class="info-item-value">{% if purchase_order.created_by %}{{ purchase_order.created_by.get_full_name|default:purchase_order.created_by.username }}{% else %}--{% endif %}</div>
+  </div>
+  <div class="info-item">
+    <div class="info-item-label">Created</div>
+    <div class="info-item-value">{{ purchase_order.created_at|date:"N j, Y, P" }}</div>
+  </div>
+  <div class="info-item">
+    <div class="info-item-label">Updated</div>
+    <div class="info-item-value">{{ purchase_order.updated_at|date:"N j, Y, P" }}</div>
+  </div>
+  {% if purchase_order.notes %}
+  <div class="info-item" style="grid-column: 1 / -1;">
+    <div class="info-item-label">Notes</div>
+    <div class="info-item-value">{{ purchase_order.notes|linebreaksbr }}</div>
+  </div>
+  {% endif %}
+</div>
+
+{# ── Line Items ── #}
+<h2 class="section-heading">Line Items</h2>
+{% if line_items %}
+<table class="data-table" style="margin-bottom: 1.5rem;">
+  <thead>
+    <tr>
+      <th>Description</th>
+      <th style="text-align: right;">Qty</th>
+      <th style="text-align: right;">Unit Price</th>
+      <th style="text-align: right;">Line Total</th>
+    </tr>
+  </thead>
+  <tbody>
+    {% for item in line_items %}
+    <tr>
+      <td>{{ item.description }}</td>
+      <td style="text-align: right;">{{ item.quantity }}</td>
+      <td style="text-align: right;">${{ item.unit_price }}</td>
+      <td style="text-align: right;">${{ item.line_total }}</td>
+    </tr>
+    {% endfor %}
+  </tbody>
+  <tfoot>
+    <tr style="border-top: 2px solid var(--color-border);">
+      <td colspan="3" style="text-align: right; font-weight: 700; padding: 0.75rem 1rem;">Subtotal</td>
+      <td style="text-align: right; font-weight: 700; padding: 0.75rem 1rem;">${{ purchase_order.subtotal }}</td>
+    </tr>
+    <tr>
+      <td colspan="3" style="text-align: right; font-weight: 700; padding: 0.5rem 1rem;">Total</td>
+      <td style="text-align: right; font-weight: 700; padding: 0.5rem 1rem; font-size: 1.05rem;">${{ purchase_order.total }}</td>
+    </tr>
+    <tr>
+      <td colspan="3" style="text-align: right; font-weight: 600; padding: 0.5rem 1rem; color: var(--color-success);">Total Paid</td>
+      <td style="text-align: right; font-weight: 600; padding: 0.5rem 1rem; color: var(--color-success);">${{ purchase_order.total_paid }}</td>
+    </tr>
+    {% if purchase_order.total_credited %}
+    <tr>
+      <td colspan="3" style="text-align: right; font-weight: 600; padding: 0.5rem 1rem; color: var(--color-accent);">Total Credits</td>
+      <td style="text-align: right; font-weight: 600; padding: 0.5rem 1rem; color: var(--color-accent);">${{ purchase_order.total_credited }}</td>
+    </tr>
+    {% endif %}
+    <tr style="border-top: 2px solid var(--color-border);">
+      <td colspan="3" style="text-align: right; font-weight: 700; padding: 0.75rem 1rem; font-size: 1.1rem;">Balance Due</td>
+      <td style="text-align: right; font-weight: 700; padding: 0.75rem 1rem; font-size: 1.1rem;
+        {% if purchase_order.balance_due > 0 %}color: var(--color-warning);
+        {% elif purchase_order.balance_due < 0 %}color: var(--color-accent);
+        {% else %}color: var(--color-success);{% endif %}">
+        ${{ purchase_order.balance_due }}
+      </td>
+    </tr>
+  </tfoot>
+</table>
+{% else %}
+<p style="color: var(--color-text-muted); margin-bottom: 1.5rem;">No line items.</p>
+{% endif %}
+
+{# ── Payments ── #}
+<h2 class="section-heading">Payments</h2>
+{% if payments %}
+<table class="data-table" style="margin-bottom: 1rem;">
+  <thead>
+    <tr>
+      <th>Date</th>
+      <th style="text-align: right;">Amount</th>
+      <th>Method</th>
+      <th>Reference</th>
+      <th>Entered By</th>
+      <th>Note</th>
+    </tr>
+  </thead>
+  <tbody>
+    {% for payment in payments %}
+    <tr>
+      <td>{{ payment.payment_date|date:"M j, Y" }}</td>
+      <td style="text-align: right; font-weight: 600;">${{ payment.amount }}</td>
+      <td>{{ payment.get_method_display }}</td>
+      <td class="mono">{% if payment.reference %}{{ payment.reference }}{% else %}<span style="color: var(--color-text-muted);">--</span>{% endif %}</td>
+      <td>{% if payment.entered_by %}{{ payment.entered_by.get_full_name|default:payment.entered_by.username }}{% else %}--{% endif %}</td>
+      <td>{% if payment.note %}{{ payment.note|truncatewords:10 }}{% else %}<span style="color: var(--color-text-muted);">--</span>{% endif %}</td>
+    </tr>
+    {% endfor %}
+  </tbody>
+</table>
+{% else %}
+<p style="color: var(--color-text-muted); margin-bottom: 1rem;">No payments recorded yet.</p>
+{% endif %}
+
+{% if purchase_order.status != "cancelled" and purchase_order.status != "paid" %}
+<div style="background: var(--color-bg); border: 1px solid var(--color-border-light); border-radius: var(--radius-md); padding: 1.25rem; margin-bottom: 2rem;">
+  <h3 style="font-size: 0.85rem; font-weight: 700; margin-bottom: 0.75rem; color: var(--color-text-secondary);">Record Payment</h3>
+  <form method="post" action="{% url 'manage:purchase-order-payment' conference.slug purchase_order.pk %}" style="display: grid; grid-template-columns: repeat(auto-fit, minmax(160px, 1fr)); gap: 0.75rem; align-items: end;">
+    {% csrf_token %}
+    <div class="form-group" style="margin-bottom: 0;">
+      <label for="pay-amount">Amount ($)</label>
+      <input type="number" id="pay-amount" name="amount" step="0.01" min="0.01" required style="padding: 0.4rem 0.6rem; border: 1px solid var(--color-border); border-radius: var(--radius-sm); font-size: 0.88rem; width: 100%;">
+    </div>
+    <div class="form-group" style="margin-bottom: 0;">
+      <label for="pay-method">Method</label>
+      <select id="pay-method" name="method" style="padding: 0.4rem 0.6rem; border: 1px solid var(--color-border); border-radius: var(--radius-sm); font-size: 0.88rem; width: 100%;">
+        {% for value, label in payment_methods %}
+        <option value="{{ value }}">{{ label }}</option>
+        {% endfor %}
+      </select>
+    </div>
+    <div class="form-group" style="margin-bottom: 0;">
+      <label for="pay-ref">Reference</label>
+      <input type="text" id="pay-ref" name="reference" placeholder="Wire transfer ID, check #, etc." style="padding: 0.4rem 0.6rem; border: 1px solid var(--color-border); border-radius: var(--radius-sm); font-size: 0.88rem; width: 100%;">
+    </div>
+    <div class="form-group" style="margin-bottom: 0;">
+      <label for="pay-date">Date</label>
+      <input type="date" id="pay-date" name="payment_date" value="{{ today }}" style="padding: 0.4rem 0.6rem; border: 1px solid var(--color-border); border-radius: var(--radius-sm); font-size: 0.88rem; width: 100%;">
+    </div>
+    <div class="form-group" style="margin-bottom: 0;">
+      <label for="pay-note">Note</label>
+      <input type="text" id="pay-note" name="note" placeholder="Optional note" style="padding: 0.4rem 0.6rem; border: 1px solid var(--color-border); border-radius: var(--radius-sm); font-size: 0.88rem; width: 100%;">
+    </div>
+    <div>
+      <button type="submit" class="btn btn-primary btn-sm">Record Payment</button>
+    </div>
+  </form>
+</div>
+{% endif %}
+
+{# ── Credit Notes ── #}
+<h2 class="section-heading">Credit Notes</h2>
+{% if credit_notes %}
+<table class="data-table" style="margin-bottom: 1rem;">
+  <thead>
+    <tr>
+      <th>Date</th>
+      <th style="text-align: right;">Amount</th>
+      <th>Reason</th>
+      <th>Issued By</th>
+    </tr>
+  </thead>
+  <tbody>
+    {% for cn in credit_notes %}
+    <tr>
+      <td>{{ cn.created_at|date:"M j, Y" }}</td>
+      <td style="text-align: right; font-weight: 600;">${{ cn.amount }}</td>
+      <td>{{ cn.reason|truncatewords:20 }}</td>
+      <td>{% if cn.issued_by %}{{ cn.issued_by.get_full_name|default:cn.issued_by.username }}{% else %}--{% endif %}</td>
+    </tr>
+    {% endfor %}
+  </tbody>
+</table>
+{% else %}
+<p style="color: var(--color-text-muted); margin-bottom: 1rem;">No credit notes issued.</p>
+{% endif %}
+
+{% if purchase_order.status != "cancelled" %}
+<div style="background: var(--color-bg); border: 1px solid var(--color-border-light); border-radius: var(--radius-md); padding: 1.25rem; margin-bottom: 2rem;">
+  <h3 style="font-size: 0.85rem; font-weight: 700; margin-bottom: 0.75rem; color: var(--color-text-secondary);">Issue Credit Note</h3>
+  <form method="post" action="{% url 'manage:purchase-order-credit' conference.slug purchase_order.pk %}" style="display: grid; grid-template-columns: 1fr 2fr auto; gap: 0.75rem; align-items: end;">
+    {% csrf_token %}
+    <div class="form-group" style="margin-bottom: 0;">
+      <label for="credit-amount">Amount ($)</label>
+      <input type="number" id="credit-amount" name="amount" step="0.01" min="0.01" required style="padding: 0.4rem 0.6rem; border: 1px solid var(--color-border); border-radius: var(--radius-sm); font-size: 0.88rem; width: 100%;">
+    </div>
+    <div class="form-group" style="margin-bottom: 0;">
+      <label for="credit-reason">Reason</label>
+      <input type="text" id="credit-reason" name="reason" required placeholder="Reason for credit" style="padding: 0.4rem 0.6rem; border: 1px solid var(--color-border); border-radius: var(--radius-sm); font-size: 0.88rem; width: 100%;">
+    </div>
+    <div>
+      <button type="submit" class="btn btn-secondary btn-sm" onclick="return confirm('Issue this credit note?');">Issue Credit</button>
+    </div>
+  </form>
+</div>
+{% endif %}
+
+{# ── Actions ── #}
+<div style="display: flex; gap: 0.75rem; align-items: center; margin-bottom: 2rem;">
+  {% if purchase_order.status == "draft" %}
+  <span style="font-size: 0.82rem; color: var(--color-text-muted);">This PO is in draft. Mark it as sent when the invoice has been delivered to the organization.</span>
+  {% endif %}
+
+  {% if purchase_order.status != "cancelled" and purchase_order.status != "paid" %}
+  <form method="post" action="{% url 'manage:purchase-order-cancel' conference.slug purchase_order.pk %}" style="display: inline;">
+    {% csrf_token %}
+    <button type="submit" class="btn btn-sm" style="color: var(--color-danger); border-color: var(--color-danger);" onclick="return confirm('Cancel this purchase order? This cannot be undone.');">Cancel PO</button>
+  </form>
+  {% endif %}
+
+  <a href="{% url 'manage:purchase-order-list' conference.slug %}" class="btn btn-secondary btn-sm">Back to List</a>
+</div>
+{% endblock %}
diff --git a/src/django_program/manage/templates/django_program/manage/purchase_order_form.html b/src/django_program/manage/templates/django_program/manage/purchase_order_form.html
new file mode 100644
index 0000000..170d2e6
--- /dev/null
+++ b/src/django_program/manage/templates/django_program/manage/purchase_order_form.html
@@ -0,0 +1,242 @@
+{% extends "django_program/manage/base.html" %}
+
+{% block title %}New Purchase Order{% endblock %}
+
+{% block breadcrumb %}
+<nav class="breadcrumb" aria-label="Breadcrumb">
+  <a href="{% url 'manage:dashboard' conference.slug %}">Dashboard</a>
+  <span class="breadcrumb-separator"></span>
+  <a href="{% url 'manage:purchase-order-list' conference.slug %}">Purchase Orders</a>
+  <span class="breadcrumb-separator"></span>
+  <span>New</span>
+</nav>
+{% endblock %}
+
+{% block page_title %}
+<h1>New Purchase Order</h1>
+<p>Create an invoice-style purchase order for corporate or organizational billing</p>
+{% endblock %}
+
+{% block content %}
+<style>
+  .po-form { max-width: 800px; }
+  .po-form .form-row {
+    display: grid;
+    gap: 1rem;
+    grid-template-columns: repeat(2, minmax(0, 1fr));
+  }
+  .fieldset {
+    margin-bottom: 1.5rem;
+    padding-bottom: 1.25rem;
+    border-bottom: 1px solid var(--color-border-light);
+  }
+  .fieldset:last-of-type {
+    border-bottom: none;
+    margin-bottom: 0;
+    padding-bottom: 0;
+  }
+  .fieldset-legend {
+    font-size: 0.78rem;
+    font-weight: 700;
+    text-transform: uppercase;
+    letter-spacing: 0.06em;
+    color: var(--color-text-muted);
+    margin-bottom: 0.75rem;
+  }
+  .line-items-table {
+    width: 100%;
+    border-collapse: collapse;
+  }
+  .line-items-table th {
+    font-size: 0.75rem;
+    font-weight: 600;
+    text-transform: uppercase;
+    letter-spacing: 0.04em;
+    color: var(--color-text-muted);
+    padding: 0.4rem 0.5rem;
+    text-align: left;
+    border-bottom: 1px solid var(--color-border);
+  }
+  .line-items-table td {
+    padding: 0.4rem 0.5rem;
+    vertical-align: middle;
+  }
+  .line-items-table input {
+    padding: 0.4rem 0.6rem;
+    border: 1px solid var(--color-border);
+    border-radius: var(--radius-sm);
+    font-size: 0.88rem;
+    width: 100%;
+  }
+  .line-items-table input:focus {
+    outline: none;
+    border-color: var(--color-primary);
+    box-shadow: 0 0 0 3px var(--color-primary-light);
+  }
+  .line-items-table .col-desc { width: 50%; }
+  .line-items-table .col-qty { width: 12%; }
+  .line-items-table .col-price { width: 18%; }
+  .line-items-table .col-total { width: 14%; text-align: right; }
+  .line-items-table .col-action { width: 6%; text-align: center; }
+  .remove-line-btn {
+    background: none;
+    border: none;
+    color: var(--color-text-muted);
+    cursor: pointer;
+    padding: 0.25rem;
+    border-radius: var(--radius-sm);
+    line-height: 1;
+    transition: color 0.15s ease;
+  }
+  .remove-line-btn:hover { color: var(--color-danger); }
+  .add-line-btn {
+    display: inline-flex;
+    align-items: center;
+    gap: 0.35rem;
+    border: 1px dashed var(--color-border);
+    background: none;
+    padding: 0.5rem 0.75rem;
+    border-radius: var(--radius-sm);
+    font-size: 0.82rem;
+    color: var(--color-text-secondary);
+    cursor: pointer;
+    transition: all 0.15s ease;
+    margin-top: 0.5rem;
+  }
+  .add-line-btn:hover {
+    border-color: var(--color-primary);
+    color: var(--color-primary);
+    background: var(--color-primary-light);
+  }
+  @media (max-width: 720px) {
+    .po-form .form-row { grid-template-columns: 1fr; }
+    .line-items-table .col-total,
+    .line-items-table .col-action { display: none; }
+  }
+</style>
+
+<div class="po-form">
+  <form method="post" id="po-form">
+    {% csrf_token %}
+
+    <div class="fieldset">
+      <div class="fieldset-legend">Organization Details</div>
+      <div class="form-row">
+        <div class="form-group">
+          <label for="id_organization_name">Organization Name *</label>
+          <input type="text" id="id_organization_name" name="organization_name" required value="{{ form_data.organization_name|default:'' }}">
+        </div>
+        <div class="form-group">
+          <label for="id_contact_email">Contact Email *</label>
+          <input type="email" id="id_contact_email" name="contact_email" required value="{{ form_data.contact_email|default:'' }}">
+        </div>
+      </div>
+      <div class="form-row">
+        <div class="form-group">
+          <label for="id_contact_name">Contact Name</label>
+          <input type="text" id="id_contact_name" name="contact_name" value="{{ form_data.contact_name|default:'' }}">
+        </div>
+        <div class="form-group">
+          <label for="id_billing_address">Billing Address</label>
+          <textarea id="id_billing_address" name="billing_address" rows="3">{{ form_data.billing_address|default:'' }}</textarea>
+        </div>
+      </div>
+    </div>
+
+    <div class="fieldset">
+      <div class="fieldset-legend">Line Items</div>
+      <table class="line-items-table" id="line-items-table">
+        <thead>
+          <tr>
+            <th class="col-desc">Description</th>
+            <th class="col-qty">Qty</th>
+            <th class="col-price">Unit Price</th>
+            <th class="col-total">Total</th>
+            <th class="col-action"></th>
+          </tr>
+        </thead>
+        <tbody id="line-items-body">
+          <tr class="line-item-row">
+            <td class="col-desc"><input type="text" name="line_description" placeholder="e.g. Corporate tickets x10" required></td>
+            <td class="col-qty"><input type="number" name="line_quantity" value="1" min="1" required></td>
+            <td class="col-price"><input type="number" name="line_unit_price" step="0.01" min="0" value="0.00" required></td>
+            <td class="col-total" style="text-align: right; font-weight: 600; color: var(--color-text-secondary); font-size: 0.88rem;">$0.00</td>
+            <td class="col-action">
+              <button type="button" class="remove-line-btn" title="Remove line item" onclick="removeLine(this)">
+                <svg width="16" height="16" fill="none" stroke="currentColor" stroke-width="1.5"><path d="M4 4l8 8M12 4l-8 8"/></svg>
+              </button>
+            </td>
+          </tr>
+        </tbody>
+      </table>
+      <button type="button" class="add-line-btn" onclick="addLine()">
+        <svg width="14" height="14" fill="none" stroke="currentColor" stroke-width="2"><path d="M7 2v10M2 7h10"/></svg>
+        Add Line Item
+      </button>
+    </div>
+
+    <div class="fieldset">
+      <div class="fieldset-legend">Notes <span style="font-weight: 400; text-transform: none; letter-spacing: normal; font-size: 0.75rem;">(optional)</span></div>
+      <div class="form-group">
+        <label for="id_notes">Internal Notes</label>
+        <textarea id="id_notes" name="notes" rows="3" placeholder="Internal notes (not shown on invoice)">{{ form_data.notes|default:'' }}</textarea>
+      </div>
+    </div>
+
+    <div class="form-actions">
+      <button type="submit" class="btn btn-primary">Create Purchase Order</button>
+      <a href="{% url 'manage:purchase-order-list' conference.slug %}" class="btn btn-secondary">Cancel</a>
+    </div>
+  </form>
+</div>
+{% endblock %}
+
+{% block extra_js %}
+<script>
+(function() {
+  function recalcRow(row) {
+    var qty = parseFloat(row.querySelector('[name="line_quantity"]').value) || 0;
+    var price = parseFloat(row.querySelector('[name="line_unit_price"]').value) || 0;
+    var totalCell = row.querySelector('.col-total');
+    if (totalCell) {
+      totalCell.textContent = '$' + (qty * price).toFixed(2);
+    }
+  }
+
+  function recalcAll() {
+    var rows = document.querySelectorAll('.line-item-row');
+    rows.forEach(recalcRow);
+  }
+
+  document.getElementById('line-items-body').addEventListener('input', function(e) {
+    if (e.target.name === 'line_quantity' || e.target.name === 'line_unit_price') {
+      recalcRow(e.target.closest('.line-item-row'));
+    }
+  });
+
+  window.addLine = function() {
+    var tbody = document.getElementById('line-items-body');
+    var row = document.createElement('tr');
+    row.className = 'line-item-row';
+    row.innerHTML =
+      '<td class="col-desc"><input type="text" name="line_description" placeholder="Description" required></td>' +
+      '<td class="col-qty"><input type="number" name="line_quantity" value="1" min="1" required></td>' +
+      '<td class="col-price"><input type="number" name="line_unit_price" step="0.01" min="0" value="0.00" required></td>' +
+      '<td class="col-total" style="text-align: right; font-weight: 600; color: var(--color-text-secondary); font-size: 0.88rem;">$0.00</td>' +
+      '<td class="col-action"><button type="button" class="remove-line-btn" title="Remove line item" onclick="removeLine(this)"><svg width="16" height="16" fill="none" stroke="currentColor" stroke-width="1.5"><path d="M4 4l8 8M12 4l-8 8"/></svg></button></td>';
+    tbody.appendChild(row);
+    row.querySelector('[name="line_description"]').focus();
+  };
+
+  window.removeLine = function(btn) {
+    var tbody = document.getElementById('line-items-body');
+    if (tbody.querySelectorAll('.line-item-row').length <= 1) {
+      return;  // Keep at least one row
+    }
+    btn.closest('.line-item-row').remove();
+  };
+
+  recalcAll();
+})();
+</script>
+{% endblock %}
diff --git a/src/django_program/manage/templates/django_program/manage/purchase_order_list.html b/src/django_program/manage/templates/django_program/manage/purchase_order_list.html
new file mode 100644
index 0000000..fc431ab
--- /dev/null
+++ b/src/django_program/manage/templates/django_program/manage/purchase_order_list.html
@@ -0,0 +1,90 @@
+{% extends "django_program/manage/base.html" %}
+
+{% block title %}Purchase Orders{% endblock %}
+
+{% block page_title %}
+<h1>Purchase Orders</h1>
+<p>Manage corporate invoices and offline payment tracking</p>
+{% endblock %}
+
+{% block page_actions %}
+<a href="{% url 'manage:purchase-order-add' conference.slug %}" class="btn btn-primary">New Purchase Order</a>
+{% endblock %}
+
+{% block content %}
+<div style="margin-bottom: 1.5rem;">
+  <form method="get" style="display: flex; align-items: center; gap: 0.75rem;">
+    <label for="status-filter" style="font-size: 0.82rem; font-weight: 600; color: var(--color-text-secondary);">Filter by status:</label>
+    <select id="status-filter" name="status" onchange="this.form.submit();" style="padding: 0.4rem 0.6rem; border: 1px solid var(--color-border); border-radius: var(--radius-sm); font-size: 0.88rem;">
+      <option value="">All</option>
+      {% for value, label in status_choices %}
+      <option value="{{ value }}" {% if current_status == value %}selected{% endif %}>{{ label }}</option>
+      {% endfor %}
+    </select>
+  </form>
+</div>
+
+{% if purchase_orders %}
+<table class="data-table">
+  <thead>
+    <tr>
+      <th>Reference</th>
+      <th>Organization</th>
+      <th>Contact</th>
+      <th>Status</th>
+      <th style="text-align: right;">Total</th>
+      <th style="text-align: right;">Balance Due</th>
+      <th>Created</th>
+      <th>Actions</th>
+    </tr>
+  </thead>
+  <tbody>
+    {% for po in purchase_orders %}
+    <tr>
+      <td class="mono">{{ po.reference }}</td>
+      <td>{{ po.organization_name }}</td>
+      <td>
+        {% if po.contact_name %}{{ po.contact_name }}{% else %}{{ po.contact_email }}{% endif %}
+      </td>
+      <td>
+        {% if po.status == "draft" %}
+        <span class="badge badge--other">Draft</span>
+        {% elif po.status == "sent" %}
+        <span class="badge badge--accepted">Sent</span>
+        {% elif po.status == "partially_paid" %}
+        <span class="badge badge--warning">Partially Paid</span>
+        {% elif po.status == "paid" %}
+        <span class="badge badge--active">Paid</span>
+        {% elif po.status == "overpaid" %}
+        <span class="badge badge--synced">Overpaid</span>
+        {% elif po.status == "cancelled" %}
+        <span class="badge badge--inactive">Cancelled</span>
+        {% endif %}
+      </td>
+      <td style="text-align: right;">${{ po.total }}</td>
+      <td style="text-align: right;">
+        {% if po.balance_due > 0 %}
+        <span style="color: var(--color-warning); font-weight: 600;">${{ po.balance_due }}</span>
+        {% elif po.balance_due < 0 %}
+        <span style="color: var(--color-accent); font-weight: 600;">-${{ po.balance_due|floatformat:2 }}</span>
+        {% else %}
+        <span style="color: var(--color-success);">$0.00</span>
+        {% endif %}
+      </td>
+      <td>{{ po.created_at|date:"M j, Y" }}</td>
+      <td>
+        <a href="{% url 'manage:purchase-order-detail' conference.slug po.pk %}" class="btn btn-sm btn-secondary">View</a>
+      </td>
+    </tr>
+    {% endfor %}
+  </tbody>
+</table>
+
+{% include "django_program/manage/_pagination.html" %}
+{% else %}
+<div class="empty-state">
+  <p>No purchase orders{% if current_status %} with status "{{ current_status }}"{% endif %} for this conference yet.</p>
+  <p><a href="{% url 'manage:purchase-order-add' conference.slug %}" class="btn btn-primary">Create First Purchase Order</a></p>
+</div>
+{% endif %}
+{% endblock %}
diff --git a/src/django_program/manage/urls.py b/src/django_program/manage/urls.py
index f312e23..58ff46f 100644
--- a/src/django_program/manage/urls.py
+++ b/src/django_program/manage/urls.py
@@ -316,6 +316,8 @@
     path("<slug:conference_slug>/vouchers/bulk/", include("django_program.manage.urls_vouchers")),
     # --- Financial Dashboard ---
     path("<slug:conference_slug>/financial/", include("django_program.manage.urls_financial")),
+    # --- Purchase Orders ---
+    path("<slug:conference_slug>/purchase-orders/", include("django_program.manage.urls_purchase_orders")),
     # --- Reports ---
     path("<slug:conference_slug>/reports/", include("django_program.manage.urls_reports")),
     # --- Analytics & KPI Dashboard ---
diff --git a/src/django_program/manage/urls_purchase_orders.py b/src/django_program/manage/urls_purchase_orders.py
new file mode 100644
index 0000000..190bd93
--- /dev/null
+++ b/src/django_program/manage/urls_purchase_orders.py
@@ -0,0 +1,25 @@
+"""URL patterns for purchase order management.
+
+Included under ``<slug:conference_slug>/purchase-orders/`` in the main
+management URL configuration.
+"""
+
+from django.urls import path
+
+from django_program.manage.views_purchase_orders import (
+    PurchaseOrderCancelView,
+    PurchaseOrderCreateView,
+    PurchaseOrderDetailView,
+    PurchaseOrderIssueCreditView,
+    PurchaseOrderListView,
+    PurchaseOrderRecordPaymentView,
+)
+
+urlpatterns = [
+    path("", PurchaseOrderListView.as_view(), name="purchase-order-list"),
+    path("add/", PurchaseOrderCreateView.as_view(), name="purchase-order-add"),
+    path("<int:pk>/", PurchaseOrderDetailView.as_view(), name="purchase-order-detail"),
+    path("<int:pk>/payment/", PurchaseOrderRecordPaymentView.as_view(), name="purchase-order-payment"),
+    path("<int:pk>/credit/", PurchaseOrderIssueCreditView.as_view(), name="purchase-order-credit"),
+    path("<int:pk>/cancel/", PurchaseOrderCancelView.as_view(), name="purchase-order-cancel"),
+]
diff --git a/src/django_program/manage/views_purchase_orders.py b/src/django_program/manage/views_purchase_orders.py
new file mode 100644
index 0000000..cbcdd94
--- /dev/null
+++ b/src/django_program/manage/views_purchase_orders.py
@@ -0,0 +1,327 @@
+"""Views for purchase order management in the organizer dashboard."""
+
+import datetime
+import logging
+from decimal import Decimal, InvalidOperation
+from typing import TYPE_CHECKING
+
+from django.contrib import messages
+from django.shortcuts import get_object_or_404, redirect
+from django.template.response import TemplateResponse
+from django.urls import reverse
+from django.utils import timezone
+from django.views import View
+from django.views.generic import DetailView, ListView
+
+from django_program.manage.views import ManagePermissionMixin
+from django_program.registration.purchase_order import (
+    PurchaseOrder,
+    PurchaseOrderCreditNote,
+    PurchaseOrderLineItem,
+    PurchaseOrderPayment,
+)
+from django_program.registration.services.purchase_orders import (
+    cancel_purchase_order,
+    create_purchase_order,
+    issue_credit_note,
+    record_payment,
+)
+
+if TYPE_CHECKING:
+    from django.db.models import QuerySet
+    from django.http import HttpRequest, HttpResponse
+
+logger = logging.getLogger(__name__)
+
+
+def _parse_line_items(
+    descriptions: list[str],
+    quantities: list[str],
+    unit_prices: list[str],
+) -> tuple[list[dict[str, object]], list[str]]:
+    """Parse and validate line item data from POST lists.
+
+    Args:
+        descriptions: Line item description values.
+        quantities: Line item quantity values.
+        unit_prices: Line item unit price values.
+
+    Returns:
+        A tuple of (valid line items, error messages).
+    """
+    items: list[dict[str, object]] = []
+    errors: list[str] = []
+    for i, raw_desc in enumerate(descriptions):
+        cleaned = raw_desc.strip()
+        if not cleaned:
+            continue
+        try:
+            qty = int(quantities[i]) if i < len(quantities) else 1
+            price = Decimal(unit_prices[i]) if i < len(unit_prices) else Decimal("0.00")
+        except ValueError, InvalidOperation:
+            errors.append(f"Invalid quantity or price for line item {i + 1}.")
+            continue
+        if qty < 1:
+            errors.append(f"Quantity must be at least 1 for line item {i + 1}.")
+            continue
+        if price < 0:
+            errors.append(f"Unit price cannot be negative for line item {i + 1}.")
+            continue
+        items.append({"description": cleaned, "quantity": qty, "unit_price": price})
+    return items, errors
+
+
+class PurchaseOrderListView(ManagePermissionMixin, ListView):
+    """List all purchase orders for the current conference.
+
+    Supports optional filtering by status via the ``?status=`` query
+    parameter.
+    """
+
+    template_name = "django_program/manage/purchase_order_list.html"
+    context_object_name = "purchase_orders"
+    paginate_by = 50
+
+    def get_context_data(self, **kwargs: object) -> dict[str, object]:
+        """Add ``active_nav`` and status filter choices to the template context."""
+        context = super().get_context_data(**kwargs)
+        context["active_nav"] = "purchase-orders"
+        context["status_choices"] = PurchaseOrder.Status.choices
+        context["current_status"] = self.request.GET.get("status", "")
+        return context
+
+    def get_queryset(self) -> QuerySet[PurchaseOrder]:
+        """Return purchase orders for the current conference, optionally filtered by status."""
+        qs = PurchaseOrder.objects.filter(conference=self.conference).order_by("-created_at")
+        status = self.request.GET.get("status", "")
+        if status and status in dict(PurchaseOrder.Status.choices):
+            qs = qs.filter(status=status)
+        return qs
+
+
+class PurchaseOrderDetailView(ManagePermissionMixin, DetailView):
+    """Display full details of a purchase order with payments and credit notes."""
+
+    template_name = "django_program/manage/purchase_order_detail.html"
+    context_object_name = "purchase_order"
+
+    def get_context_data(self, **kwargs: object) -> dict[str, object]:
+        """Add ``active_nav``, line items, payments, and credit notes to context."""
+        context = super().get_context_data(**kwargs)
+        context["active_nav"] = "purchase-orders"
+        po = self.object
+        context["line_items"] = PurchaseOrderLineItem.objects.filter(purchase_order=po)
+        context["payments"] = PurchaseOrderPayment.objects.filter(purchase_order=po).select_related("entered_by")
+        context["credit_notes"] = PurchaseOrderCreditNote.objects.filter(purchase_order=po).select_related("issued_by")
+        context["payment_methods"] = PurchaseOrderPayment.Method.choices
+        return context
+
+    def get_queryset(self) -> QuerySet[PurchaseOrder]:
+        """Scope to the current conference."""
+        return PurchaseOrder.objects.filter(conference=self.conference)
+
+
+class PurchaseOrderCreateView(ManagePermissionMixin, View):
+    """Create a new purchase order with line items.
+
+    GET renders the create form. POST validates input and creates the PO
+    via the service layer, then redirects to the detail view.
+    """
+
+    def get(self, request: HttpRequest, **kwargs: str) -> HttpResponse:  # noqa: ARG002
+        """Render the blank purchase order form."""
+        return TemplateResponse(
+            request,
+            "django_program/manage/purchase_order_form.html",
+            {
+                "conference": self.conference,
+                "active_nav": "purchase-orders",
+                "submission_type_nav": self.get_submission_type_nav(),
+            },
+        )
+
+    def post(self, request: HttpRequest, **kwargs: str) -> HttpResponse:  # noqa: ARG002
+        """Validate and create a purchase order from form data."""
+        organization_name = request.POST.get("organization_name", "").strip()
+        contact_email = request.POST.get("contact_email", "").strip()
+        contact_name = request.POST.get("contact_name", "").strip()
+        billing_address = request.POST.get("billing_address", "").strip()
+        notes = request.POST.get("notes", "").strip()
+
+        errors: list[str] = []
+        if not organization_name:
+            errors.append("Organization name is required.")
+        if not contact_email:
+            errors.append("Contact email is required.")
+
+        line_items, line_errors = _parse_line_items(
+            request.POST.getlist("line_description"),
+            request.POST.getlist("line_quantity"),
+            request.POST.getlist("line_unit_price"),
+        )
+        errors.extend(line_errors)
+
+        if not line_items and not line_errors:
+            errors.append("At least one line item is required.")
+
+        if errors:
+            for err in errors:
+                messages.error(request, err)
+            return TemplateResponse(
+                request,
+                "django_program/manage/purchase_order_form.html",
+                {
+                    "conference": self.conference,
+                    "active_nav": "purchase-orders",
+                    "submission_type_nav": self.get_submission_type_nav(),
+                    "form_data": {
+                        "organization_name": organization_name,
+                        "contact_email": contact_email,
+                        "contact_name": contact_name,
+                        "billing_address": billing_address,
+                        "notes": notes,
+                    },
+                    "line_items_data": line_items,
+                },
+            )
+
+        try:
+            po = create_purchase_order(
+                conference=self.conference,
+                organization_name=organization_name,
+                contact_email=contact_email,
+                contact_name=contact_name,
+                billing_address=billing_address,
+                line_items=line_items,
+                notes=notes,
+                created_by=request.user,
+            )
+        except Exception:
+            logger.exception("Failed to create purchase order")
+            messages.error(request, "Failed to create purchase order. Please try again.")
+            return redirect(reverse("manage:purchase-order-list", kwargs={"conference_slug": self.conference.slug}))
+
+        messages.success(request, f"Purchase order {po.reference} created.")
+        return redirect(
+            reverse(
+                "manage:purchase-order-detail",
+                kwargs={"conference_slug": self.conference.slug, "pk": po.pk},
+            )
+        )
+
+
+class PurchaseOrderRecordPaymentView(ManagePermissionMixin, View):
+    """Record a payment against a purchase order (POST-only)."""
+
+    def post(self, request: HttpRequest, **kwargs: str) -> HttpResponse:  # noqa: ARG002
+        """Validate and record a payment."""
+        po = get_object_or_404(PurchaseOrder, pk=self.kwargs["pk"], conference=self.conference)
+        detail_url = reverse(
+            "manage:purchase-order-detail",
+            kwargs={"conference_slug": self.conference.slug, "pk": po.pk},
+        )
+
+        try:
+            amount = Decimal(request.POST.get("amount", "0"))
+        except InvalidOperation:
+            messages.error(request, "Invalid payment amount.")
+            return redirect(detail_url)
+
+        if amount <= 0:
+            messages.error(request, "Payment amount must be positive.")
+            return redirect(detail_url)
+
+        method = request.POST.get("method", PurchaseOrderPayment.Method.WIRE)
+        if method not in dict(PurchaseOrderPayment.Method.choices):
+            method = PurchaseOrderPayment.Method.WIRE
+
+        reference_str = request.POST.get("reference", "").strip()
+        note = request.POST.get("note", "").strip()
+        payment_date_str = request.POST.get("payment_date", "")
+
+        today = timezone.now().date()
+        try:
+            payment_date = datetime.date.fromisoformat(payment_date_str) if payment_date_str else today
+        except ValueError:
+            payment_date = today
+
+        try:
+            record_payment(
+                po,
+                amount=amount,
+                method=method,
+                reference=reference_str,
+                payment_date=payment_date,
+                entered_by=request.user,
+                note=note,
+            )
+        except Exception:
+            logger.exception("Failed to record payment for PO %s", po.reference)
+            messages.error(request, "Failed to record payment. Please try again.")
+            return redirect(detail_url)
+
+        messages.success(request, f"Payment of ${amount} recorded for {po.reference}.")
+        return redirect(detail_url)
+
+
+class PurchaseOrderIssueCreditView(ManagePermissionMixin, View):
+    """Issue a credit note against a purchase order (POST-only)."""
+
+    def post(self, request: HttpRequest, **kwargs: str) -> HttpResponse:  # noqa: ARG002
+        """Validate and issue a credit note."""
+        po = get_object_or_404(PurchaseOrder, pk=self.kwargs["pk"], conference=self.conference)
+        detail_url = reverse(
+            "manage:purchase-order-detail",
+            kwargs={"conference_slug": self.conference.slug, "pk": po.pk},
+        )
+
+        try:
+            amount = Decimal(request.POST.get("amount", "0"))
+        except InvalidOperation:
+            messages.error(request, "Invalid credit amount.")
+            return redirect(detail_url)
+
+        if amount <= 0:
+            messages.error(request, "Credit amount must be positive.")
+            return redirect(detail_url)
+
+        reason = request.POST.get("reason", "").strip()
+        if not reason:
+            messages.error(request, "A reason is required for credit notes.")
+            return redirect(detail_url)
+
+        try:
+            issue_credit_note(po, amount=amount, reason=reason, issued_by=request.user)
+        except Exception:
+            logger.exception("Failed to issue credit note for PO %s", po.reference)
+            messages.error(request, "Failed to issue credit note. Please try again.")
+            return redirect(detail_url)
+
+        messages.success(request, f"Credit note of ${amount} issued for {po.reference}.")
+        return redirect(detail_url)
+
+
+class PurchaseOrderCancelView(ManagePermissionMixin, View):
+    """Cancel a purchase order (POST-only)."""
+
+    def post(self, request: HttpRequest, **kwargs: str) -> HttpResponse:  # noqa: ARG002
+        """Cancel the purchase order."""
+        po = get_object_or_404(PurchaseOrder, pk=self.kwargs["pk"], conference=self.conference)
+        detail_url = reverse(
+            "manage:purchase-order-detail",
+            kwargs={"conference_slug": self.conference.slug, "pk": po.pk},
+        )
+
+        if po.status in (PurchaseOrder.Status.CANCELLED, PurchaseOrder.Status.PAID):
+            messages.error(request, f"Cannot cancel a purchase order with status '{po.get_status_display()}'.")
+            return redirect(detail_url)
+
+        try:
+            cancel_purchase_order(po)
+        except Exception:
+            logger.exception("Failed to cancel PO %s", po.reference)
+            messages.error(request, "Failed to cancel purchase order. Please try again.")
+            return redirect(detail_url)
+
+        messages.success(request, f"Purchase order {po.reference} has been cancelled.")
+        return redirect(detail_url)
diff --git a/tests/test_registration/test_purchase_orders.py b/tests/test_registration/test_purchase_orders.py
new file mode 100644
index 0000000..7b642e7
--- /dev/null
+++ b/tests/test_registration/test_purchase_orders.py
@@ -0,0 +1,585 @@
+"""Tests for purchase order models and service functions."""
+
+import re
+from datetime import date
+from decimal import Decimal
+
+import pytest
+from django.contrib.auth import get_user_model
+
+from django_program.conference.models import Conference
+from django_program.registration.models import AddOn, TicketType
+from django_program.registration.purchase_order import (
+    PurchaseOrder,
+    PurchaseOrderCreditNote,
+    PurchaseOrderPayment,
+)
+from django_program.registration.services.purchase_orders import (
+    cancel_purchase_order,
+    create_purchase_order,
+    generate_po_reference,
+    issue_credit_note,
+    record_payment,
+    update_po_status,
+)
+
+User = get_user_model()
+
+
+# -- Fixtures -----------------------------------------------------------------
+
+
+@pytest.fixture
+def conference() -> Conference:
+    return Conference.objects.create(
+        name="TestCon",
+        slug="testcon-po",
+        start_date=date(2027, 6, 1),
+        end_date=date(2027, 6, 3),
+        timezone="UTC",
+    )
+
+
+@pytest.fixture
+def user() -> User:
+    return User.objects.create_user(
+        username="pouser",
+        email="po@example.com",
+        password="testpass123",
+    )
+
+
+@pytest.fixture
+def staff_user() -> User:
+    return User.objects.create_user(
+        username="postaffuser",
+        email="postaff@example.com",
+        password="testpass123",
+        is_staff=True,
+    )
+
+
+@pytest.fixture
+def ticket_type(conference: Conference) -> TicketType:
+    return TicketType.objects.create(
+        conference=conference,
+        name="Corporate",
+        slug="corporate",
+        price=Decimal("250.00"),
+        total_quantity=0,
+        limit_per_user=10,
+        is_active=True,
+    )
+
+
+@pytest.fixture
+def addon(conference: Conference) -> AddOn:
+    return AddOn.objects.create(
+        conference=conference,
+        name="Workshop",
+        slug="workshop",
+        price=Decimal("75.00"),
+        is_active=True,
+    )
+
+
+@pytest.fixture
+def sample_line_items(ticket_type: TicketType, addon: AddOn) -> list[dict]:
+    return [
+        {
+            "description": "Corporate Ticket",
+            "quantity": 5,
+            "unit_price": Decimal("250.00"),
+            "ticket_type": ticket_type,
+        },
+        {
+            "description": "Workshop Add-On",
+            "quantity": 3,
+            "unit_price": Decimal("75.00"),
+            "addon": addon,
+        },
+    ]
+
+
+@pytest.fixture
+def purchase_order(conference: Conference, staff_user: User, sample_line_items: list[dict]) -> PurchaseOrder:
+    return create_purchase_order(
+        conference=conference,
+        organization_name="Acme Corp",
+        contact_email="billing@acme.com",
+        contact_name="Jane Doe",
+        billing_address="123 Corporate Ave",
+        line_items=sample_line_items,
+        notes="Test PO",
+        created_by=staff_user,
+    )
+
+
+# =============================================================================
+# Model tests
+# =============================================================================
+
+
+@pytest.mark.unit
+@pytest.mark.django_db
+class TestPurchaseOrderModel:
+    def test_str_returns_reference_and_status(self, purchase_order: PurchaseOrder) -> None:
+        result = str(purchase_order)
+        assert purchase_order.reference in result
+        assert "draft" in result
+
+    def test_balance_due_no_payments(self, purchase_order: PurchaseOrder) -> None:
+        # 5 * 250 + 3 * 75 = 1475
+        assert purchase_order.total == Decimal("1475.00")
+        assert purchase_order.balance_due == Decimal("1475.00")
+
+    def test_balance_due_with_payment(self, purchase_order: PurchaseOrder) -> None:
+        PurchaseOrderPayment.objects.create(
+            purchase_order=purchase_order,
+            amount=Decimal("500.00"),
+            method=PurchaseOrderPayment.Method.WIRE,
+            payment_date=date(2027, 5, 1),
+        )
+        assert purchase_order.balance_due == Decimal("975.00")
+
+    def test_balance_due_with_credit(self, purchase_order: PurchaseOrder) -> None:
+        PurchaseOrderCreditNote.objects.create(
+            purchase_order=purchase_order,
+            amount=Decimal("200.00"),
+            reason="Adjustment",
+        )
+        assert purchase_order.balance_due == Decimal("1275.00")
+
+    def test_balance_due_with_payment_and_credit(self, purchase_order: PurchaseOrder) -> None:
+        PurchaseOrderPayment.objects.create(
+            purchase_order=purchase_order,
+            amount=Decimal("1000.00"),
+            method=PurchaseOrderPayment.Method.ACH,
+            payment_date=date(2027, 5, 1),
+        )
+        PurchaseOrderCreditNote.objects.create(
+            purchase_order=purchase_order,
+            amount=Decimal("100.00"),
+            reason="Partial cancellation",
+        )
+        # 1475 - 1000 - 100 = 375
+        assert purchase_order.balance_due == Decimal("375.00")
+
+    def test_total_paid_sums_payments(self, purchase_order: PurchaseOrder) -> None:
+        PurchaseOrderPayment.objects.create(
+            purchase_order=purchase_order,
+            amount=Decimal("300.00"),
+            method=PurchaseOrderPayment.Method.WIRE,
+            payment_date=date(2027, 5, 1),
+        )
+        PurchaseOrderPayment.objects.create(
+            purchase_order=purchase_order,
+            amount=Decimal("200.00"),
+            method=PurchaseOrderPayment.Method.CHECK,
+            payment_date=date(2027, 5, 15),
+        )
+        assert purchase_order.total_paid == Decimal("500.00")
+
+    def test_total_paid_zero_when_no_payments(self, purchase_order: PurchaseOrder) -> None:
+        assert purchase_order.total_paid == Decimal("0.00")
+
+
+@pytest.mark.unit
+@pytest.mark.django_db
+class TestPurchaseOrderLineItemModel:
+    def test_str_returns_quantity_and_description(self, purchase_order: PurchaseOrder) -> None:
+        item = purchase_order.line_items.first()
+        assert item is not None
+        result = str(item)
+        assert "Corporate Ticket" in result
+        assert "5" in result
+
+
+@pytest.mark.unit
+@pytest.mark.django_db
+class TestPurchaseOrderPaymentModel:
+    def test_str_returns_method_amount_and_date(self, purchase_order: PurchaseOrder) -> None:
+        payment = PurchaseOrderPayment.objects.create(
+            purchase_order=purchase_order,
+            amount=Decimal("500.00"),
+            method=PurchaseOrderPayment.Method.WIRE,
+            payment_date=date(2027, 5, 1),
+        )
+        result = str(payment)
+        assert "500.00" in result
+        assert "Wire Transfer" in result
+        assert "2027-05-01" in result
+
+
+@pytest.mark.unit
+@pytest.mark.django_db
+class TestPurchaseOrderCreditNoteModel:
+    def test_str_returns_amount_and_reason(self, purchase_order: PurchaseOrder) -> None:
+        cn = PurchaseOrderCreditNote.objects.create(
+            purchase_order=purchase_order,
+            amount=Decimal("100.00"),
+            reason="Speaker discount applied",
+        )
+        result = str(cn)
+        assert "100.00" in result
+        assert "Speaker discount" in result
+
+
+# =============================================================================
+# Service tests
+# =============================================================================
+
+
+@pytest.mark.integration
+@pytest.mark.django_db
+class TestGeneratePOReference:
+    def test_returns_po_prefix(self) -> None:
+        ref = generate_po_reference()
+        assert ref.startswith("PO-")
+
+    def test_suffix_is_6_alphanumeric_chars(self) -> None:
+        ref = generate_po_reference()
+        suffix = ref.split("-", 1)[1]
+        assert len(suffix) == 6
+        assert re.match(r"^[A-Z0-9]+$", suffix)
+
+    def test_generates_unique_references(self) -> None:
+        refs = {generate_po_reference() for _ in range(20)}
+        assert len(refs) == 20
+
+
+@pytest.mark.integration
+@pytest.mark.django_db
+class TestCreatePurchaseOrder:
+    def test_creates_po_with_line_items(
+        self,
+        conference: Conference,
+        staff_user: User,
+        sample_line_items: list[dict],
+    ) -> None:
+        po = create_purchase_order(
+            conference=conference,
+            organization_name="Widgets Inc",
+            contact_email="billing@widgets.com",
+            contact_name="Bob Smith",
+            line_items=sample_line_items,
+            created_by=staff_user,
+        )
+
+        assert po.pk is not None
+        assert po.organization_name == "Widgets Inc"
+        assert po.contact_email == "billing@widgets.com"
+        assert po.line_items.count() == 2
+
+    def test_computes_correct_subtotal_and_total(
+        self,
+        conference: Conference,
+        sample_line_items: list[dict],
+    ) -> None:
+        po = create_purchase_order(
+            conference=conference,
+            organization_name="TestOrg",
+            contact_email="test@org.com",
+            contact_name="Tester",
+            line_items=sample_line_items,
+        )
+        # 5 * 250 + 3 * 75 = 1250 + 225 = 1475
+        assert po.subtotal == Decimal("1475.00")
+        assert po.total == Decimal("1475.00")
+
+    def test_reference_is_assigned(
+        self,
+        conference: Conference,
+        sample_line_items: list[dict],
+    ) -> None:
+        po = create_purchase_order(
+            conference=conference,
+            organization_name="RefOrg",
+            contact_email="ref@org.com",
+            contact_name="Ref Person",
+            line_items=sample_line_items,
+        )
+        assert po.reference.startswith("PO-")
+        assert len(po.reference) == 9  # "PO-" + 6 chars
+
+    def test_status_is_draft(
+        self,
+        conference: Conference,
+        sample_line_items: list[dict],
+    ) -> None:
+        po = create_purchase_order(
+            conference=conference,
+            organization_name="DraftOrg",
+            contact_email="draft@org.com",
+            contact_name="Drafter",
+            line_items=sample_line_items,
+        )
+        assert po.status == PurchaseOrder.Status.DRAFT
+
+    def test_empty_line_items_creates_zero_total(
+        self,
+        conference: Conference,
+    ) -> None:
+        po = create_purchase_order(
+            conference=conference,
+            organization_name="EmptyOrg",
+            contact_email="empty@org.com",
+            contact_name="Empty Person",
+            line_items=[],
+        )
+        assert po.subtotal == Decimal("0.00")
+        assert po.total == Decimal("0.00")
+        assert po.line_items.count() == 0
+
+    def test_line_items_snapshot_pricing(
+        self,
+        conference: Conference,
+        ticket_type: TicketType,
+    ) -> None:
+        items = [
+            {
+                "description": "Ticket",
+                "quantity": 2,
+                "unit_price": Decimal("300.00"),
+                "ticket_type": ticket_type,
+            },
+        ]
+        po = create_purchase_order(
+            conference=conference,
+            organization_name="SnapshotOrg",
+            contact_email="snap@org.com",
+            contact_name="Snap",
+            line_items=items,
+        )
+        line = po.line_items.first()
+        assert line is not None
+        assert line.unit_price == Decimal("300.00")
+        assert line.line_total == Decimal("600.00")
+        assert line.ticket_type == ticket_type
+
+
+@pytest.mark.integration
+@pytest.mark.django_db
+class TestRecordPayment:
+    def test_partial_payment_sets_partially_paid(self, purchase_order: PurchaseOrder, staff_user: User) -> None:
+        record_payment(
+            purchase_order,
+            amount=Decimal("500.00"),
+            method=PurchaseOrderPayment.Method.WIRE,
+            payment_date=date(2027, 5, 1),
+            entered_by=staff_user,
+        )
+        purchase_order.refresh_from_db()
+        assert purchase_order.status == PurchaseOrder.Status.PARTIALLY_PAID
+
+    def test_full_payment_sets_paid(self, purchase_order: PurchaseOrder) -> None:
+        record_payment(
+            purchase_order,
+            amount=Decimal("1475.00"),
+            method=PurchaseOrderPayment.Method.ACH,
+            payment_date=date(2027, 5, 1),
+        )
+        purchase_order.refresh_from_db()
+        assert purchase_order.status == PurchaseOrder.Status.PAID
+
+    def test_overpayment_sets_overpaid(self, purchase_order: PurchaseOrder) -> None:
+        record_payment(
+            purchase_order,
+            amount=Decimal("2000.00"),
+            method=PurchaseOrderPayment.Method.STRIPE,
+            payment_date=date(2027, 5, 1),
+        )
+        purchase_order.refresh_from_db()
+        assert purchase_order.status == PurchaseOrder.Status.OVERPAID
+
+    def test_multiple_partial_payments_then_full(self, purchase_order: PurchaseOrder) -> None:
+        record_payment(
+            purchase_order,
+            amount=Decimal("500.00"),
+            method=PurchaseOrderPayment.Method.WIRE,
+            payment_date=date(2027, 5, 1),
+        )
+        purchase_order.refresh_from_db()
+        assert purchase_order.status == PurchaseOrder.Status.PARTIALLY_PAID
+
+        record_payment(
+            purchase_order,
+            amount=Decimal("975.00"),
+            method=PurchaseOrderPayment.Method.CHECK,
+            payment_date=date(2027, 5, 15),
+        )
+        purchase_order.refresh_from_db()
+        assert purchase_order.status == PurchaseOrder.Status.PAID
+
+    def test_payment_creates_record(self, purchase_order: PurchaseOrder, staff_user: User) -> None:
+        payment = record_payment(
+            purchase_order,
+            amount=Decimal("750.00"),
+            method=PurchaseOrderPayment.Method.WIRE,
+            reference="WIRE-12345",
+            payment_date=date(2027, 5, 1),
+            entered_by=staff_user,
+            note="First installment",
+        )
+        assert payment.pk is not None
+        assert payment.amount == Decimal("750.00")
+        assert payment.reference == "WIRE-12345"
+        assert payment.entered_by == staff_user
+        assert payment.note == "First installment"
+
+
+@pytest.mark.integration
+@pytest.mark.django_db
+class TestIssueCreditNote:
+    def test_creates_credit_note(self, purchase_order: PurchaseOrder, staff_user: User) -> None:
+        cn = issue_credit_note(
+            purchase_order,
+            amount=Decimal("200.00"),
+            reason="Speaker comp adjustment",
+            issued_by=staff_user,
+        )
+        assert cn.pk is not None
+        assert cn.amount == Decimal("200.00")
+        assert cn.reason == "Speaker comp adjustment"
+        assert cn.issued_by == staff_user
+
+    def test_credit_reduces_balance(self, purchase_order: PurchaseOrder) -> None:
+        issue_credit_note(
+            purchase_order,
+            amount=Decimal("475.00"),
+            reason="Discount",
+        )
+        purchase_order.refresh_from_db()
+        # 1475 - 475 = 1000
+        assert purchase_order.balance_due == Decimal("1000.00")
+
+    def test_credit_plus_payment_marks_paid(self, purchase_order: PurchaseOrder) -> None:
+        issue_credit_note(
+            purchase_order,
+            amount=Decimal("475.00"),
+            reason="Sponsor comp",
+        )
+        record_payment(
+            purchase_order,
+            amount=Decimal("1000.00"),
+            method=PurchaseOrderPayment.Method.WIRE,
+            payment_date=date(2027, 5, 1),
+        )
+        purchase_order.refresh_from_db()
+        assert purchase_order.status == PurchaseOrder.Status.PAID
+        assert purchase_order.balance_due == Decimal("0.00")
+
+
+@pytest.mark.integration
+@pytest.mark.django_db
+class TestUpdatePOStatus:
+    def test_draft_stays_draft_with_no_payments(self, purchase_order: PurchaseOrder) -> None:
+        update_po_status(purchase_order)
+        purchase_order.refresh_from_db()
+        assert purchase_order.status == PurchaseOrder.Status.DRAFT
+
+    def test_sent_stays_sent_with_no_payments(self, purchase_order: PurchaseOrder) -> None:
+        purchase_order.status = PurchaseOrder.Status.SENT
+        purchase_order.save(update_fields=["status"])
+        update_po_status(purchase_order)
+        purchase_order.refresh_from_db()
+        assert purchase_order.status == PurchaseOrder.Status.SENT
+
+    def test_cancelled_is_not_changed(self, purchase_order: PurchaseOrder) -> None:
+        purchase_order.status = PurchaseOrder.Status.CANCELLED
+        purchase_order.save(update_fields=["status"])
+        # Record a payment directly (bypassing service)
+        PurchaseOrderPayment.objects.create(
+            purchase_order=purchase_order,
+            amount=Decimal("1475.00"),
+            method=PurchaseOrderPayment.Method.WIRE,
+            payment_date=date(2027, 5, 1),
+        )
+        update_po_status(purchase_order)
+        purchase_order.refresh_from_db()
+        assert purchase_order.status == PurchaseOrder.Status.CANCELLED
+
+
+@pytest.mark.integration
+@pytest.mark.django_db
+class TestCancelPurchaseOrder:
+    def test_cancel_draft_po(self, purchase_order: PurchaseOrder) -> None:
+        cancel_purchase_order(purchase_order)
+        purchase_order.refresh_from_db()
+        assert purchase_order.status == PurchaseOrder.Status.CANCELLED
+
+    def test_cancel_sent_po(self, purchase_order: PurchaseOrder) -> None:
+        purchase_order.status = PurchaseOrder.Status.SENT
+        purchase_order.save(update_fields=["status"])
+        cancel_purchase_order(purchase_order)
+        purchase_order.refresh_from_db()
+        assert purchase_order.status == PurchaseOrder.Status.CANCELLED
+
+    def test_cancel_paid_po_still_cancels(self, purchase_order: PurchaseOrder) -> None:
+        # The service unconditionally sets CANCELLED (no guard against paid POs)
+        record_payment(
+            purchase_order,
+            amount=Decimal("1475.00"),
+            method=PurchaseOrderPayment.Method.WIRE,
+            payment_date=date(2027, 5, 1),
+        )
+        purchase_order.refresh_from_db()
+        assert purchase_order.status == PurchaseOrder.Status.PAID
+
+        cancel_purchase_order(purchase_order)
+        purchase_order.refresh_from_db()
+        assert purchase_order.status == PurchaseOrder.Status.CANCELLED
+
+    def test_cancelled_po_ignores_status_updates(self, purchase_order: PurchaseOrder) -> None:
+        cancel_purchase_order(purchase_order)
+        # Attempting to update status after cancellation is a no-op
+        update_po_status(purchase_order)
+        purchase_order.refresh_from_db()
+        assert purchase_order.status == PurchaseOrder.Status.CANCELLED
+
+    def test_cancel_preserves_payment_records(self, purchase_order: PurchaseOrder) -> None:
+        record_payment(
+            purchase_order,
+            amount=Decimal("500.00"),
+            method=PurchaseOrderPayment.Method.WIRE,
+            payment_date=date(2027, 5, 1),
+        )
+        cancel_purchase_order(purchase_order)
+        assert purchase_order.payments.count() == 1
+
+
+# =============================================================================
+# Admin registration tests
+# =============================================================================
+
+
+@pytest.mark.integration
+@pytest.mark.django_db
+class TestPurchaseOrderAdmin:
+    def test_admin_list_display_fields(self) -> None:
+        from django_program.registration.admin import PurchaseOrderAdmin
+
+        expected_fields = {
+            "reference",
+            "organization_name",
+            "conference",
+            "status",
+            "total",
+            "balance_due_display",
+            "created_at",
+        }
+        assert set(PurchaseOrderAdmin.list_display) == expected_fields
+
+    def test_admin_has_search_fields(self) -> None:
+        from django_program.registration.admin import PurchaseOrderAdmin
+
+        assert "reference" in PurchaseOrderAdmin.search_fields
+        assert "organization_name" in PurchaseOrderAdmin.search_fields
+        assert "contact_email" in PurchaseOrderAdmin.search_fields
+
+    def test_admin_has_readonly_money_fields(self) -> None:
+        from django_program.registration.admin import PurchaseOrderAdmin
+
+        assert "subtotal" in PurchaseOrderAdmin.readonly_fields
+        assert "total" in PurchaseOrderAdmin.readonly_fields
+        assert "reference" in PurchaseOrderAdmin.readonly_fields

From 70207ee1960d5b31c8f710501843862790eb6519 Mon Sep 17 00:00:00 2001
From: Jacob Coffee <jacob@z7x.org>
Date: Thu, 19 Mar 2026 13:31:21 -0500
Subject: [PATCH 4/7] =?UTF-8?q?fix:=20address=20Codex=20review=20=E2=80=94?=
 =?UTF-8?q?=20lifecycle=20guards,=20race=20conditions,=20credit-only=20set?=
 =?UTF-8?q?tlement?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

- Add select_for_update() locking in record_payment/issue_credit_note
- Reject mutations on cancelled POs (ValueError)
- Fix credit-only PO settlement (was stuck in draft/sent)
- Add send_purchase_order() service + Send PO view/URL/button
- Make admin payment/credit inlines read-only
- Add 5 new tests for lifecycle guards and send flow

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 .../manage/purchase_order_detail.html         |  5 +-
 .../manage/urls_purchase_orders.py            |  2 +
 .../manage/views_purchase_orders.py           | 34 +++++++++++
 src/django_program/registration/admin.py      | 27 +++++++-
 .../registration/services/purchase_orders.py  | 57 ++++++++++++++---
 .../test_registration/test_purchase_orders.py | 61 +++++++++++++++++++
 6 files changed, 175 insertions(+), 11 deletions(-)

diff --git a/src/django_program/manage/templates/django_program/manage/purchase_order_detail.html b/src/django_program/manage/templates/django_program/manage/purchase_order_detail.html
index 0b4921b..0ba4daf 100644
--- a/src/django_program/manage/templates/django_program/manage/purchase_order_detail.html
+++ b/src/django_program/manage/templates/django_program/manage/purchase_order_detail.html
@@ -243,7 +243,10 @@ <h3 style="font-size: 0.85rem; font-weight: 700; margin-bottom: 0.75rem; color:
 {# ── Actions ── #}
 <div style="display: flex; gap: 0.75rem; align-items: center; margin-bottom: 2rem;">
   {% if purchase_order.status == "draft" %}
-  <span style="font-size: 0.82rem; color: var(--color-text-muted);">This PO is in draft. Mark it as sent when the invoice has been delivered to the organization.</span>
+  <form method="post" action="{% url 'manage:purchase-order-send' conference.slug purchase_order.pk %}" style="display: inline;">
+    {% csrf_token %}
+    <button type="submit" class="btn btn-primary btn-sm" onclick="return confirm('Mark this PO as sent?');">Mark as Sent</button>
+  </form>
   {% endif %}
 
   {% if purchase_order.status != "cancelled" and purchase_order.status != "paid" %}
diff --git a/src/django_program/manage/urls_purchase_orders.py b/src/django_program/manage/urls_purchase_orders.py
index 190bd93..8abeb0b 100644
--- a/src/django_program/manage/urls_purchase_orders.py
+++ b/src/django_program/manage/urls_purchase_orders.py
@@ -13,6 +13,7 @@
     PurchaseOrderIssueCreditView,
     PurchaseOrderListView,
     PurchaseOrderRecordPaymentView,
+    PurchaseOrderSendView,
 )
 
 urlpatterns = [
@@ -22,4 +23,5 @@
     path("<int:pk>/payment/", PurchaseOrderRecordPaymentView.as_view(), name="purchase-order-payment"),
     path("<int:pk>/credit/", PurchaseOrderIssueCreditView.as_view(), name="purchase-order-credit"),
     path("<int:pk>/cancel/", PurchaseOrderCancelView.as_view(), name="purchase-order-cancel"),
+    path("<int:pk>/send/", PurchaseOrderSendView.as_view(), name="purchase-order-send"),
 ]
diff --git a/src/django_program/manage/views_purchase_orders.py b/src/django_program/manage/views_purchase_orders.py
index cbcdd94..eb4237a 100644
--- a/src/django_program/manage/views_purchase_orders.py
+++ b/src/django_program/manage/views_purchase_orders.py
@@ -25,6 +25,7 @@
     create_purchase_order,
     issue_credit_note,
     record_payment,
+    send_purchase_order,
 )
 
 if TYPE_CHECKING:
@@ -221,6 +222,10 @@ def post(self, request: HttpRequest, **kwargs: str) -> HttpResponse:  # noqa: AR
             kwargs={"conference_slug": self.conference.slug, "pk": po.pk},
         )
 
+        if po.status == PurchaseOrder.Status.CANCELLED:
+            messages.error(request, "Cannot record payment on a cancelled purchase order.")
+            return redirect(detail_url)
+
         try:
             amount = Decimal(request.POST.get("amount", "0"))
         except InvalidOperation:
@@ -275,6 +280,10 @@ def post(self, request: HttpRequest, **kwargs: str) -> HttpResponse:  # noqa: AR
             kwargs={"conference_slug": self.conference.slug, "pk": po.pk},
         )
 
+        if po.status == PurchaseOrder.Status.CANCELLED:
+            messages.error(request, "Cannot issue credit on a cancelled purchase order.")
+            return redirect(detail_url)
+
         try:
             amount = Decimal(request.POST.get("amount", "0"))
         except InvalidOperation:
@@ -325,3 +334,28 @@ def post(self, request: HttpRequest, **kwargs: str) -> HttpResponse:  # noqa: AR
 
         messages.success(request, f"Purchase order {po.reference} has been cancelled.")
         return redirect(detail_url)
+
+
+class PurchaseOrderSendView(ManagePermissionMixin, View):
+    """Mark a draft purchase order as sent (POST-only)."""
+
+    def post(self, request: HttpRequest, **kwargs: str) -> HttpResponse:  # noqa: ARG002
+        """Transition the PO from draft to sent."""
+        po = get_object_or_404(PurchaseOrder, pk=self.kwargs["pk"], conference=self.conference)
+        detail_url = reverse(
+            "manage:purchase-order-detail",
+            kwargs={"conference_slug": self.conference.slug, "pk": po.pk},
+        )
+
+        try:
+            send_purchase_order(po)
+        except ValueError as exc:
+            messages.error(request, str(exc))
+            return redirect(detail_url)
+        except Exception:
+            logger.exception("Failed to send PO %s", po.reference)
+            messages.error(request, "Failed to send purchase order. Please try again.")
+            return redirect(detail_url)
+
+        messages.success(request, f"Purchase order {po.reference} marked as sent.")
+        return redirect(detail_url)
diff --git a/src/django_program/registration/admin.py b/src/django_program/registration/admin.py
index 41dc025..4f4c01d 100644
--- a/src/django_program/registration/admin.py
+++ b/src/django_program/registration/admin.py
@@ -506,17 +506,40 @@ class PurchaseOrderLineItemInline(admin.TabularInline):
 
 
 class PurchaseOrderPaymentInline(admin.TabularInline):
-    """Inline display of payments recorded against a purchase order."""
+    """Read-only inline display of payments recorded against a purchase order.
+
+    Payments should be recorded through the management dashboard to ensure
+    proper status transitions. The inline is read-only to prevent bypassing
+    the service layer invariants.
+    """
 
     model = PurchaseOrderPayment
     extra = 0
+    readonly_fields = ("amount", "method", "reference", "payment_date", "entered_by", "note", "created_at")
+
+    def has_add_permission(self, request: HttpRequest, obj: PurchaseOrder | None = None) -> bool:  # noqa: ARG002, D102
+        return False
+
+    def has_delete_permission(self, request: HttpRequest, obj: PurchaseOrder | None = None) -> bool:  # noqa: ARG002, D102
+        return False
 
 
 class PurchaseOrderCreditNoteInline(admin.TabularInline):
-    """Inline display of credit notes issued against a purchase order."""
+    """Read-only inline display of credit notes issued against a purchase order.
+
+    Credit notes should be issued through the management dashboard to ensure
+    proper status recalculation. The inline is read-only for audit integrity.
+    """
 
     model = PurchaseOrderCreditNote
     extra = 0
+    readonly_fields = ("amount", "reason", "issued_by", "created_at")
+
+    def has_add_permission(self, request: HttpRequest, obj: PurchaseOrder | None = None) -> bool:  # noqa: ARG002, D102
+        return False
+
+    def has_delete_permission(self, request: HttpRequest, obj: PurchaseOrder | None = None) -> bool:  # noqa: ARG002, D102
+        return False
 
 
 @admin.register(PurchaseOrder)
diff --git a/src/django_program/registration/services/purchase_orders.py b/src/django_program/registration/services/purchase_orders.py
index b7c3092..5023463 100644
--- a/src/django_program/registration/services/purchase_orders.py
+++ b/src/django_program/registration/services/purchase_orders.py
@@ -158,9 +158,18 @@ def record_payment(  # noqa: PLR0913
 
     Returns:
         The newly created PurchaseOrderPayment.
+
+    Raises:
+        ValueError: If the PO is cancelled.
     """
+    # Lock the PO row to prevent concurrent status races.
+    po = PurchaseOrder.objects.select_for_update().get(pk=purchase_order.pk)
+    if po.status == PurchaseOrder.Status.CANCELLED:
+        msg = f"Cannot record payment on cancelled PO {po.reference}"
+        raise ValueError(msg)
+
     payment = PurchaseOrderPayment.objects.create(
-        purchase_order=purchase_order,
+        purchase_order=po,
         amount=amount,
         method=method,
         reference=reference,
@@ -169,7 +178,7 @@ def record_payment(  # noqa: PLR0913
         note=note,
     )
 
-    update_po_status(purchase_order)
+    update_po_status(po)
 
     logger.info(
         "Recorded %s payment of %s for PO %s",
@@ -198,15 +207,24 @@ def issue_credit_note(
 
     Returns:
         The newly created PurchaseOrderCreditNote.
+
+    Raises:
+        ValueError: If the PO is cancelled.
     """
+    # Lock the PO row to prevent concurrent status races.
+    po = PurchaseOrder.objects.select_for_update().get(pk=purchase_order.pk)
+    if po.status == PurchaseOrder.Status.CANCELLED:
+        msg = f"Cannot issue credit note on cancelled PO {po.reference}"
+        raise ValueError(msg)
+
     credit_note = PurchaseOrderCreditNote.objects.create(
-        purchase_order=purchase_order,
+        purchase_order=po,
         amount=amount,
         reason=reason,
         issued_by=issued_by,
     )
 
-    update_po_status(purchase_order)
+    update_po_status(po)
 
     logger.info(
         "Issued credit note of %s for PO %s: %s",
@@ -221,23 +239,29 @@ def update_po_status(purchase_order: PurchaseOrder) -> None:
     """Recompute and save the PO status based on payments and credits.
 
     Status transitions:
-    - ``draft`` remains if no payments and status is draft
-    - ``paid`` when balance_due is exactly zero
+    - ``draft`` remains if no payments/credits and status is draft
+    - ``paid`` when balance_due is exactly zero and financial activity exists
     - ``overpaid`` when balance_due is negative
     - ``partially_paid`` when some payments exist but balance remains
     - ``sent`` when no payments exist and status is not draft
 
+    This function expects the caller to hold a row-level lock on the PO
+    (via ``select_for_update``) when called inside a transaction.
+
     Args:
         purchase_order: The PO whose status should be recomputed.
     """
+    purchase_order.refresh_from_db()
+
     if purchase_order.status == PurchaseOrder.Status.CANCELLED:
         return
 
-    purchase_order.refresh_from_db()
     balance = purchase_order.balance_due
     total_paid = purchase_order.total_paid
+    total_credited = purchase_order.total_credited
+    has_financial_activity = total_paid > Decimal("0.00") or total_credited > Decimal("0.00")
 
-    if balance == Decimal("0.00") and total_paid > Decimal("0.00"):
+    if balance == Decimal("0.00") and has_financial_activity:
         new_status = PurchaseOrder.Status.PAID
     elif balance < Decimal("0.00"):
         new_status = PurchaseOrder.Status.OVERPAID
@@ -253,6 +277,23 @@ def update_po_status(purchase_order: PurchaseOrder) -> None:
         purchase_order.save(update_fields=["status", "updated_at"])
 
 
+def send_purchase_order(purchase_order: PurchaseOrder) -> None:
+    """Transition a draft purchase order to sent status.
+
+    Args:
+        purchase_order: The PO to mark as sent.
+
+    Raises:
+        ValueError: If the PO is not in draft status.
+    """
+    if purchase_order.status != PurchaseOrder.Status.DRAFT:
+        msg = f"Only draft POs can be sent (current status: {purchase_order.status})"
+        raise ValueError(msg)
+    purchase_order.status = PurchaseOrder.Status.SENT
+    purchase_order.save(update_fields=["status", "updated_at"])
+    logger.info("Marked purchase order %s as sent", purchase_order.reference)
+
+
 def cancel_purchase_order(purchase_order: PurchaseOrder) -> None:
     """Cancel a purchase order.
 
diff --git a/tests/test_registration/test_purchase_orders.py b/tests/test_registration/test_purchase_orders.py
index 7b642e7..8b2f331 100644
--- a/tests/test_registration/test_purchase_orders.py
+++ b/tests/test_registration/test_purchase_orders.py
@@ -20,6 +20,7 @@
     generate_po_reference,
     issue_credit_note,
     record_payment,
+    send_purchase_order,
     update_po_status,
 )
 
@@ -583,3 +584,63 @@ def test_admin_has_readonly_money_fields(self) -> None:
         assert "subtotal" in PurchaseOrderAdmin.readonly_fields
         assert "total" in PurchaseOrderAdmin.readonly_fields
         assert "reference" in PurchaseOrderAdmin.readonly_fields
+
+
+# =============================================================================
+# Send PO tests
+# =============================================================================
+
+
+@pytest.mark.integration
+@pytest.mark.django_db
+class TestSendPurchaseOrder:
+    def test_send_draft_po(self, purchase_order: PurchaseOrder) -> None:
+        send_purchase_order(purchase_order)
+        purchase_order.refresh_from_db()
+        assert purchase_order.status == PurchaseOrder.Status.SENT
+
+    def test_send_non_draft_raises(self, purchase_order: PurchaseOrder) -> None:
+        purchase_order.status = PurchaseOrder.Status.PAID
+        purchase_order.save(update_fields=["status"])
+        with pytest.raises(ValueError, match="Only draft POs"):
+            send_purchase_order(purchase_order)
+
+
+# =============================================================================
+# Lifecycle guard tests (Codex review findings)
+# =============================================================================
+
+
+@pytest.mark.integration
+@pytest.mark.django_db
+class TestLifecycleGuards:
+    def test_record_payment_on_cancelled_raises(self, purchase_order: PurchaseOrder) -> None:
+        cancel_purchase_order(purchase_order)
+        with pytest.raises(ValueError, match="cancelled"):
+            record_payment(
+                purchase_order,
+                amount=Decimal("100.00"),
+                method=PurchaseOrderPayment.Method.WIRE,
+                payment_date=date(2027, 5, 1),
+            )
+
+    def test_issue_credit_on_cancelled_raises(self, purchase_order: PurchaseOrder) -> None:
+        cancel_purchase_order(purchase_order)
+        with pytest.raises(ValueError, match="cancelled"):
+            issue_credit_note(
+                purchase_order,
+                amount=Decimal("100.00"),
+                reason="Test credit",
+            )
+
+    def test_credit_only_settles_po(self, purchase_order: PurchaseOrder) -> None:
+        """A PO settled entirely by credit notes should reach PAID status."""
+        purchase_order.status = PurchaseOrder.Status.SENT
+        purchase_order.save(update_fields=["status"])
+        issue_credit_note(
+            purchase_order,
+            amount=purchase_order.total,
+            reason="Full credit applied",
+        )
+        purchase_order.refresh_from_db()
+        assert purchase_order.status == PurchaseOrder.Status.PAID

From 88ee43701082f27cc98222ff0255c33257005328 Mon Sep 17 00:00:00 2001
From: Jacob Coffee <jacob@z7x.org>
Date: Thu, 19 Mar 2026 13:44:49 -0500
Subject: [PATCH 5/7] feat: add invoice PDF, Stripe/QBO invoicing, and
 financial dashboard PO metrics

- Invoice PDF generation via reportlab with conference-prefixed filenames
- Stripe Invoicing integration (create/send/sync invoices via Stripe API)
- QuickBooks Online integration via httpx (create/send/sync invoices)
- PO metrics on financial dashboard (status breakdown, revenue, balance, payments by method)
- Conference model: QBO OAuth fields (realm_id, tokens, client credentials)
- PurchaseOrder model: stripe_invoice_id/url and qbo_invoice_id/url fields

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 examples/seed.py                              |  18 +-
 pyproject.toml                                |   1 +
 .../migrations/0010_add_qbo_fields.py         |  57 ++
 src/django_program/conference/models.py       |  39 ++
 src/django_program/manage/forms.py            |  17 +-
 .../templates/django_program/manage/base.html |  69 ++-
 .../manage/conference_edit.html               |  45 ++
 .../manage/financial_dashboard.html           | 123 ++++
 .../manage/purchase_order_detail.html         |  28 +
 .../manage/urls_purchase_orders.py            |   6 +
 src/django_program/manage/views.py            |  38 +-
 src/django_program/manage/views_financial.py  |  64 ++
 .../manage/views_purchase_orders.py           | 119 +++-
 .../migrations/0021_add_qbo_invoice_fields.py |  49 ++
 .../registration/purchase_order.py            |  24 +
 .../registration/services/purchase_orders.py  | 345 ++++++++++-
 .../registration/services/qbo_invoicing.py    | 566 ++++++++++++++++++
 .../registration/services/stripe_invoicing.py | 314 ++++++++++
 uv.lock                                       |   2 +
 19 files changed, 1914 insertions(+), 10 deletions(-)
 create mode 100644 src/django_program/conference/migrations/0010_add_qbo_fields.py
 create mode 100644 src/django_program/registration/migrations/0021_add_qbo_invoice_fields.py
 create mode 100644 src/django_program/registration/services/qbo_invoicing.py
 create mode 100644 src/django_program/registration/services/stripe_invoicing.py

diff --git a/examples/seed.py b/examples/seed.py
index 4f79e89..e20a281 100644
--- a/examples/seed.py
+++ b/examples/seed.py
@@ -27,7 +27,7 @@
 from django.core.management import call_command
 from django.utils import timezone
 
-from django_program.conference.models import Conference, Expense, ExpenseCategory
+from django_program.conference.models import Conference, Expense, ExpenseCategory, KPITargets
 from django_program.pretalx.models import Room, ScheduleSlot, SessionRating, Speaker, Talk, TalkOverride
 from django_program.programs.models import Activity, ActivitySignup, Survey, SurveyResponse, TravelGrant
 from django_program.registration.badge import Badge, BadgeTemplate
@@ -164,6 +164,7 @@ def run(self) -> None:
         """Create a full conference with realistic registration data."""
         self._create_superuser()
         conference = self._create_conference()
+        self._create_kpi_targets(conference)
         prev_conferences = self._create_previous_conferences()
         ticket_types = self._create_ticket_types(conference)
         addons = self._create_addons(conference)
@@ -325,6 +326,21 @@ def _create_conference(self) -> Conference:
         )
         return conference
 
+    def _create_kpi_targets(self, conference: Conference) -> KPITargets:
+        """Create KPI target thresholds for the conference."""
+        kpi, _ = KPITargets.objects.update_or_create(
+            conference=conference,
+            defaults={
+                "target_conversion_rate": Decimal("3.50"),
+                "target_refund_rate": Decimal("5.00"),
+                "target_checkin_rate": Decimal("80.00"),
+                "target_fulfillment_rate": Decimal("90.00"),
+                "target_revenue_per_attendee": Decimal("333.00"),
+                "target_room_utilization": Decimal("28.00"),
+            },
+        )
+        return kpi
+
     def _create_ticket_types(self, conference: Conference) -> list[TicketType]:
         """Ensure seed ticket types exist and have bulk_enabled / availability windows set."""
         now = timezone.now()
diff --git a/pyproject.toml b/pyproject.toml
index 7202bcc..816f4a1 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -49,6 +49,7 @@ classifiers = [
 dependencies = [
     "django>=5.2",
     "django-fernet-encrypted-fields>=0.3.1",
+    "httpx>=0.28.1",
     "pillow>=12.1.1",
     "pretalx-client>=0.1.0",
     "qrcode[pil]>=8.2",
diff --git a/src/django_program/conference/migrations/0010_add_qbo_fields.py b/src/django_program/conference/migrations/0010_add_qbo_fields.py
new file mode 100644
index 0000000..ae8dd95
--- /dev/null
+++ b/src/django_program/conference/migrations/0010_add_qbo_fields.py
@@ -0,0 +1,57 @@
+# Generated by Django 5.2.11 on 2026-03-19 18:36
+
+import encrypted_fields.fields
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("program_conference", "0009_featureflags_visa_letters_enabled"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="conference",
+            name="qbo_access_token",
+            field=encrypted_fields.fields.EncryptedCharField(
+                blank=True, default=None, help_text="QBO OAuth2 access token.", max_length=2000, null=True
+            ),
+        ),
+        migrations.AddField(
+            model_name="conference",
+            name="qbo_client_id",
+            field=models.CharField(
+                blank=True, default="", help_text="QBO OAuth2 client ID for token refresh.", max_length=200
+            ),
+        ),
+        migrations.AddField(
+            model_name="conference",
+            name="qbo_client_secret",
+            field=encrypted_fields.fields.EncryptedCharField(
+                blank=True,
+                default=None,
+                help_text="QBO OAuth2 client secret for token refresh.",
+                max_length=500,
+                null=True,
+            ),
+        ),
+        migrations.AddField(
+            model_name="conference",
+            name="qbo_realm_id",
+            field=models.CharField(
+                blank=True, default="", help_text="QuickBooks Online Company/Realm ID.", max_length=200
+            ),
+        ),
+        migrations.AddField(
+            model_name="conference",
+            name="qbo_refresh_token",
+            field=encrypted_fields.fields.EncryptedCharField(
+                blank=True, default=None, help_text="QBO OAuth2 refresh token.", max_length=2000, null=True
+            ),
+        ),
+        migrations.AddField(
+            model_name="conference",
+            name="qbo_token_expires_at",
+            field=models.DateTimeField(blank=True, help_text="When the QBO access token expires.", null=True),
+        ),
+    ]
diff --git a/src/django_program/conference/models.py b/src/django_program/conference/models.py
index 80f2d71..2711a46 100644
--- a/src/django_program/conference/models.py
+++ b/src/django_program/conference/models.py
@@ -27,6 +27,45 @@ class Conference(models.Model):
     stripe_publishable_key = EncryptedCharField(max_length=200, blank=True, null=True, default=None)
     stripe_webhook_secret = EncryptedCharField(max_length=200, blank=True, null=True, default=None)
 
+    qbo_realm_id = models.CharField(
+        max_length=200,
+        blank=True,
+        default="",
+        help_text="QuickBooks Online Company/Realm ID.",
+    )
+    qbo_access_token = EncryptedCharField(
+        max_length=2000,
+        blank=True,
+        null=True,
+        default=None,
+        help_text="QBO OAuth2 access token.",
+    )
+    qbo_refresh_token = EncryptedCharField(
+        max_length=2000,
+        blank=True,
+        null=True,
+        default=None,
+        help_text="QBO OAuth2 refresh token.",
+    )
+    qbo_token_expires_at = models.DateTimeField(
+        null=True,
+        blank=True,
+        help_text="When the QBO access token expires.",
+    )
+    qbo_client_id = models.CharField(
+        max_length=200,
+        blank=True,
+        default="",
+        help_text="QBO OAuth2 client ID for token refresh.",
+    )
+    qbo_client_secret = EncryptedCharField(
+        max_length=500,
+        blank=True,
+        null=True,
+        default=None,
+        help_text="QBO OAuth2 client secret for token refresh.",
+    )
+
     total_capacity = models.PositiveIntegerField(
         default=0,
         help_text="Maximum total tickets across all types. 0 means unlimited.",
diff --git a/src/django_program/manage/forms.py b/src/django_program/manage/forms.py
index c3bc077..cf2695a 100644
--- a/src/django_program/manage/forms.py
+++ b/src/django_program/manage/forms.py
@@ -11,7 +11,7 @@
 from django import forms
 from django.core.validators import RegexValidator
 
-from django_program.conference.models import Conference, Expense, ExpenseCategory, Section
+from django_program.conference.models import Conference, Expense, ExpenseCategory, KPITargets, Section
 from django_program.pretalx.models import Room, ScheduleSlot, Talk
 from django_program.programs.models import Activity, TravelGrant, TravelGrantMessage
 from django_program.registration.badge import BadgeTemplate
@@ -101,6 +101,21 @@ class Meta:
         }
 
 
+class KPITargetsForm(forms.ModelForm):
+    """Form for editing per-conference KPI target thresholds."""
+
+    class Meta:
+        model = KPITargets
+        fields = [
+            "target_conversion_rate",
+            "target_refund_rate",
+            "target_checkin_rate",
+            "target_fulfillment_rate",
+            "target_revenue_per_attendee",
+            "target_room_utilization",
+        ]
+
+
 class SectionForm(forms.ModelForm):
     """Form for editing a conference section."""
 
diff --git a/src/django_program/manage/templates/django_program/manage/base.html b/src/django_program/manage/templates/django_program/manage/base.html
index 288d4b6..b0089e4 100644
--- a/src/django_program/manage/templates/django_program/manage/base.html
+++ b/src/django_program/manage/templates/django_program/manage/base.html
@@ -203,6 +203,39 @@
       color: var(--color-text-muted);
       padding: 0.5rem 0.75rem 0.2rem;
       opacity: 0.7;
+      display: flex;
+      align-items: center;
+      justify-content: space-between;
+      cursor: pointer;
+      user-select: none;
+      border-radius: var(--radius-sm);
+      transition: opacity 0.15s ease;
+    }
+    .sidebar-sublabel:hover {
+      opacity: 1;
+    }
+    .sidebar-sublabel .sidebar-collapse-icon {
+      width: 10px;
+      height: 10px;
+      flex-shrink: 0;
+      opacity: 0.5;
+      transition: transform 0.2s ease, opacity 0.15s ease;
+    }
+    .sidebar-sublabel:hover .sidebar-collapse-icon {
+      opacity: 0.8;
+    }
+    .sidebar-subgroup {
+      max-height: 500px;
+      opacity: 1;
+      overflow: hidden;
+      transition: max-height 0.25s ease, opacity 0.2s ease;
+    }
+    .sidebar-subgroup.collapsed {
+      max-height: 0;
+      opacity: 0;
+    }
+    .sidebar-sublabel.collapsed-label .sidebar-collapse-icon {
+      transform: rotate(-90deg);
     }
 
     .sidebar-utility-separator {
@@ -1116,7 +1149,10 @@
       <div class="sidebar-section" data-section="registration">
         <div class="sidebar-section-title">Registration <svg class="sidebar-collapse-icon" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round"><path d="M4 6l4 4 4-4"/></svg></div>
         <ul class="sidebar-nav">
-          <li class="sidebar-sublabel">People</li>
+          <li class="sidebar-sublabel" data-subsection="reg-people">People <svg class="sidebar-collapse-icon" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round"><path d="M4 6l4 4 4-4"/></svg></li>
+        </ul>
+        <div class="sidebar-subgroup" data-subsection-target="reg-people">
+        <ul class="sidebar-nav">
           <li>
             <a href="{% url 'manage:attendee-list' conference.slug %}" class="{% if active_nav == 'attendees' %}active{% endif %}">
               <span class="sidebar-nav-icon"><svg width="16" height="16" fill="none" stroke="currentColor" stroke-width="1.5"><circle cx="6" cy="4.5" r="2.5"/><path d="M1 13c0-2.8 2.2-5 5-5s5 2.2 5 5"/><circle cx="12" cy="5.5" r="1.5"/><path d="M15 13c0-1.7-1.3-3-3-3-.8 0-1.5.3-2 .8"/></svg></span> Attendees
@@ -1137,7 +1173,13 @@
               <span class="sidebar-nav-icon"><svg width="16" height="16" fill="none" stroke="currentColor" stroke-width="1.5"><rect x="2" y="3" width="12" height="10" rx="1.5"/><circle cx="7" cy="7" r="1.5"/><path d="M9.5 10V6.5h1"/><path d="M12 10V8.5"/></svg></span> Badges
             </a>
           </li>
-          <li class="sidebar-sublabel">Commerce</li>
+        </ul>
+        </div>
+        <ul class="sidebar-nav">
+          <li class="sidebar-sublabel" data-subsection="reg-commerce">Commerce <svg class="sidebar-collapse-icon" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round"><path d="M4 6l4 4 4-4"/></svg></li>
+        </ul>
+        <div class="sidebar-subgroup" data-subsection-target="reg-commerce">
+        <ul class="sidebar-nav">
           <li>
             <a href="{% url 'manage:ticket-type-list' conference.slug %}" class="{% if active_nav == 'ticket-types' %}active{% endif %}">
               <span class="sidebar-nav-icon"><svg width="16" height="16" fill="none" stroke="currentColor" stroke-width="1.5"><path d="M2 4.5h12V7a1.5 1.5 0 010 3v2.5H2V10a1.5 1.5 0 010-3V4.5z"/></svg></span> Ticket Types
@@ -1164,6 +1206,7 @@
             </a>
           </li>
         </ul>
+        </div>
       </div>
 
       {# ── Sponsors ── #}
@@ -1290,11 +1333,11 @@
     var stored = {};
     try { stored = JSON.parse(localStorage.getItem(KEY) || '{}'); } catch(e) {}
 
+    // Section-level collapse
     document.querySelectorAll('.sidebar-section[data-section]').forEach(function(section) {
       var id = section.dataset.section;
       var title = section.querySelector('.sidebar-section-title');
 
-      // Restore saved state (but never collapse a section that has the active nav item)
       var hasActive = section.querySelector('.sidebar-nav li a.active, .sidebar-subnav li a.active');
       if (stored[id] && !hasActive) {
         section.classList.add('collapsed');
@@ -1306,6 +1349,26 @@
         try { localStorage.setItem(KEY, JSON.stringify(stored)); } catch(e) {}
       });
     });
+
+    // Sub-section collapse (People, Commerce, etc.)
+    document.querySelectorAll('.sidebar-sublabel[data-subsection]').forEach(function(label) {
+      var id = label.dataset.subsection;
+      var target = document.querySelector('.sidebar-subgroup[data-subsection-target="' + id + '"]');
+      if (!target) return;
+
+      var hasActive = target.querySelector('a.active');
+      if (stored[id] && !hasActive) {
+        target.classList.add('collapsed');
+        label.classList.add('collapsed-label');
+      }
+
+      label.addEventListener('click', function() {
+        target.classList.toggle('collapsed');
+        label.classList.toggle('collapsed-label');
+        stored[id] = target.classList.contains('collapsed');
+        try { localStorage.setItem(KEY, JSON.stringify(stored)); } catch(e) {}
+      });
+    });
   })();
   </script>
 </body>
diff --git a/src/django_program/manage/templates/django_program/manage/conference_edit.html b/src/django_program/manage/templates/django_program/manage/conference_edit.html
index f32900f..58ad657 100644
--- a/src/django_program/manage/templates/django_program/manage/conference_edit.html
+++ b/src/django_program/manage/templates/django_program/manage/conference_edit.html
@@ -172,6 +172,51 @@ <h1>Conference Settings</h1>
       </div>
     </div>
 
+    <div class="fieldset">
+      <div class="fieldset-legend">KPI Targets</div>
+      <p class="helptext" style="margin-bottom: 0.75rem;">Override analytics dashboard thresholds. Leave blank to use industry defaults.</p>
+      <div class="form-row--3">
+        <div class="form-group">
+          <label for="{{ kpi_form.target_conversion_rate.id_for_label }}">Conversion rate (%)</label>
+          {{ kpi_form.target_conversion_rate }}
+          <span class="helptext">{{ kpi_form.target_conversion_rate.help_text }}</span>
+          {% for error in kpi_form.target_conversion_rate.errors %}<ul class="errorlist"><li>{{ error }}</li></ul>{% endfor %}
+        </div>
+        <div class="form-group">
+          <label for="{{ kpi_form.target_refund_rate.id_for_label }}">Refund rate (%)</label>
+          {{ kpi_form.target_refund_rate }}
+          <span class="helptext">{{ kpi_form.target_refund_rate.help_text }}</span>
+          {% for error in kpi_form.target_refund_rate.errors %}<ul class="errorlist"><li>{{ error }}</li></ul>{% endfor %}
+        </div>
+        <div class="form-group">
+          <label for="{{ kpi_form.target_checkin_rate.id_for_label }}">Check-in rate (%)</label>
+          {{ kpi_form.target_checkin_rate }}
+          <span class="helptext">{{ kpi_form.target_checkin_rate.help_text }}</span>
+          {% for error in kpi_form.target_checkin_rate.errors %}<ul class="errorlist"><li>{{ error }}</li></ul>{% endfor %}
+        </div>
+      </div>
+      <div class="form-row--3">
+        <div class="form-group">
+          <label for="{{ kpi_form.target_fulfillment_rate.id_for_label }}">Fulfillment rate (%)</label>
+          {{ kpi_form.target_fulfillment_rate }}
+          <span class="helptext">{{ kpi_form.target_fulfillment_rate.help_text }}</span>
+          {% for error in kpi_form.target_fulfillment_rate.errors %}<ul class="errorlist"><li>{{ error }}</li></ul>{% endfor %}
+        </div>
+        <div class="form-group">
+          <label for="{{ kpi_form.target_revenue_per_attendee.id_for_label }}">Revenue per attendee ($)</label>
+          {{ kpi_form.target_revenue_per_attendee }}
+          <span class="helptext">{{ kpi_form.target_revenue_per_attendee.help_text }}</span>
+          {% for error in kpi_form.target_revenue_per_attendee.errors %}<ul class="errorlist"><li>{{ error }}</li></ul>{% endfor %}
+        </div>
+        <div class="form-group">
+          <label for="{{ kpi_form.target_room_utilization.id_for_label }}">Room utilization (%)</label>
+          {{ kpi_form.target_room_utilization }}
+          <span class="helptext">{{ kpi_form.target_room_utilization.help_text }}</span>
+          {% for error in kpi_form.target_room_utilization.errors %}<ul class="errorlist"><li>{{ error }}</li></ul>{% endfor %}
+        </div>
+      </div>
+    </div>
+
     <div class="fieldset">
       <div class="fieldset-legend">Integrations &amp; Status</div>
       <div class="form-row--tail">
diff --git a/src/django_program/manage/templates/django_program/manage/financial_dashboard.html b/src/django_program/manage/templates/django_program/manage/financial_dashboard.html
index 30e60c0..2b7764c 100644
--- a/src/django_program/manage/templates/django_program/manage/financial_dashboard.html
+++ b/src/django_program/manage/templates/django_program/manage/financial_dashboard.html
@@ -373,6 +373,129 @@ <h2 class="section-heading">Active Carts</h2>
 </div>
 {% endif %}
 
+{# ── Purchase Orders ── #}
+{% if total_pos %}
+<h2 class="section-heading">Purchase Orders</h2>
+<div class="top-stats" style="display: grid; grid-template-columns: repeat(4, 1fr); gap: 1rem; margin-bottom: 1.5rem;">
+  <div class="stat-card">
+    <div class="stat-card-value">{{ total_pos }}</div>
+    <div class="stat-card-label">Total POs</div>
+    {% if po_by_status.paid.count %}
+    <div style="font-size: 0.78rem; margin-top: 0.25rem; color: var(--color-success); font-weight: 500;">{{ po_by_status.paid.count }} paid</div>
+    {% endif %}
+  </div>
+  <div class="stat-card">
+    <div class="stat-card-value">${{ po_revenue|floatformat:2 }}</div>
+    <div class="stat-card-label">PO Revenue (Invoiced)</div>
+  </div>
+  <div class="stat-card">
+    <div class="stat-card-value">${{ po_collected|floatformat:2 }}</div>
+    <div class="stat-card-label">PO Payments Collected</div>
+  </div>
+  <div class="stat-card">
+    <div class="stat-card-value" style="{% if po_balance_outstanding > 0 %}color: var(--color-warning);{% else %}color: var(--color-success);{% endif %}">${{ po_balance_outstanding|floatformat:2 }}</div>
+    <div class="stat-card-label">PO Balance Outstanding</div>
+  </div>
+</div>
+
+<div style="display: grid; grid-template-columns: 1fr 1fr; gap: 2rem; margin-bottom: 2rem;">
+  <div>
+    <h3 style="font-size: 0.9rem; font-weight: 700; margin-bottom: 0.75rem; color: var(--color-text-secondary);">POs by Status</h3>
+    <table class="data-table">
+      <thead>
+        <tr>
+          <th>Status</th>
+          <th style="text-align: right;">Count</th>
+          <th style="text-align: right;">Total Value</th>
+        </tr>
+      </thead>
+      <tbody>
+        {% for status, data in po_by_status.items %}
+        {% if data.count %}
+        <tr>
+          <td>
+            {% if status == "paid" %}<span class="badge badge--active">Paid</span>
+            {% elif status == "draft" %}<span class="badge badge--other">Draft</span>
+            {% elif status == "sent" %}<span class="badge badge--accepted">Sent</span>
+            {% elif status == "partially_paid" %}<span class="badge badge--warning">Partially Paid</span>
+            {% elif status == "overpaid" %}<span class="badge badge--synced">Overpaid</span>
+            {% elif status == "cancelled" %}<span class="badge badge--inactive">Cancelled</span>
+            {% endif %}
+          </td>
+          <td style="text-align: right; font-family: var(--font-mono);">{{ data.count }}</td>
+          <td style="text-align: right; font-family: var(--font-mono);">${{ data.total|floatformat:2 }}</td>
+        </tr>
+        {% endif %}
+        {% endfor %}
+      </tbody>
+    </table>
+  </div>
+
+  <div>
+    <h3 style="font-size: 0.9rem; font-weight: 700; margin-bottom: 0.75rem; color: var(--color-text-secondary);">PO Payments by Method</h3>
+    <table class="data-table">
+      <thead>
+        <tr>
+          <th>Method</th>
+          <th style="text-align: right;">Count</th>
+          <th style="text-align: right;">Amount</th>
+        </tr>
+      </thead>
+      <tbody>
+        {% for method, data in po_payments_by_method.items %}
+        {% if data.count %}
+        <tr>
+          <td>{{ data.label }}</td>
+          <td style="text-align: right; font-family: var(--font-mono);">{{ data.count }}</td>
+          <td style="text-align: right; font-family: var(--font-mono);">${{ data.total|floatformat:2 }}</td>
+        </tr>
+        {% endif %}
+        {% endfor %}
+      </tbody>
+    </table>
+  </div>
+</div>
+
+{% if recent_pos %}
+<h3 style="font-size: 0.9rem; font-weight: 700; margin-bottom: 0.75rem; color: var(--color-text-secondary);">Recent Purchase Orders</h3>
+<table class="data-table" style="margin-bottom: 2rem;">
+  <thead>
+    <tr>
+      <th>Reference</th>
+      <th>Organization</th>
+      <th>Status</th>
+      <th style="text-align: right;">Total</th>
+      <th style="text-align: right;">Balance Due</th>
+      <th>Created</th>
+    </tr>
+  </thead>
+  <tbody>
+    {% for po in recent_pos %}
+    <tr>
+      <td><a href="{% url 'manage:purchase-order-detail' conference.slug po.pk %}" class="mono">{{ po.reference }}</a></td>
+      <td>{{ po.organization_name }}</td>
+      <td>
+        {% if po.status == "paid" %}<span class="badge badge--active">Paid</span>
+        {% elif po.status == "draft" %}<span class="badge badge--other">Draft</span>
+        {% elif po.status == "sent" %}<span class="badge badge--accepted">Sent</span>
+        {% elif po.status == "partially_paid" %}<span class="badge badge--warning">Partially Paid</span>
+        {% elif po.status == "overpaid" %}<span class="badge badge--synced">Overpaid</span>
+        {% elif po.status == "cancelled" %}<span class="badge badge--inactive">Cancelled</span>
+        {% endif %}
+      </td>
+      <td style="text-align: right; font-family: var(--font-mono);">${{ po.total|floatformat:2 }}</td>
+      <td style="text-align: right; font-family: var(--font-mono);
+        {% if po.balance_due > 0 %}color: var(--color-warning);{% elif po.balance_due == 0 %}color: var(--color-success);{% endif %}">
+        ${{ po.balance_due|floatformat:2 }}
+      </td>
+      <td>{{ po.created_at|date:"M j, Y" }}</td>
+    </tr>
+    {% endfor %}
+  </tbody>
+</table>
+{% endif %}
+{% endif %}
+
 <style>
   @media (max-width: 900px) {
     .top-stats { grid-template-columns: repeat(2, 1fr) !important; }
diff --git a/src/django_program/manage/templates/django_program/manage/purchase_order_detail.html b/src/django_program/manage/templates/django_program/manage/purchase_order_detail.html
index 0ba4daf..d27a68a 100644
--- a/src/django_program/manage/templates/django_program/manage/purchase_order_detail.html
+++ b/src/django_program/manage/templates/django_program/manage/purchase_order_detail.html
@@ -242,6 +242,8 @@ <h3 style="font-size: 0.85rem; font-weight: 700; margin-bottom: 0.75rem; color:
 
 {# ── Actions ── #}
 <div style="display: flex; gap: 0.75rem; align-items: center; margin-bottom: 2rem;">
+  <a href="{% url 'manage:purchase-order-invoice' conference.slug purchase_order.pk %}" class="btn btn-primary btn-sm">Download Invoice PDF</a>
+
   {% if purchase_order.status == "draft" %}
   <form method="post" action="{% url 'manage:purchase-order-send' conference.slug purchase_order.pk %}" style="display: inline;">
     {% csrf_token %}
@@ -249,6 +251,32 @@ <h3 style="font-size: 0.85rem; font-weight: 700; margin-bottom: 0.75rem; color:
   </form>
   {% endif %}
 
+  {% if purchase_order.status == "draft" or purchase_order.status == "sent" %}
+    {% if conference.stripe_secret_key and not purchase_order.stripe_invoice_id %}
+    <form method="post" action="{% url 'manage:purchase-order-stripe-invoice' conference.slug purchase_order.pk %}" style="display: inline;">
+      {% csrf_token %}
+      <button type="submit" class="btn btn-primary btn-sm" onclick="return confirm('Create and send a Stripe invoice for this PO?');">Send Stripe Invoice</button>
+    </form>
+    {% endif %}
+  {% endif %}
+
+  {% if purchase_order.stripe_invoice_url %}
+  <a href="{{ purchase_order.stripe_invoice_url }}" target="_blank" rel="noopener" class="btn btn-sm btn-secondary">View Stripe Invoice</a>
+  {% endif %}
+
+  {% if purchase_order.status == "draft" or purchase_order.status == "sent" %}
+    {% if conference.qbo_realm_id and not purchase_order.qbo_invoice_id %}
+    <form method="post" action="{% url 'manage:purchase-order-qbo-invoice' conference.slug purchase_order.pk %}" style="display: inline;">
+      {% csrf_token %}
+      <button type="submit" class="btn btn-sm btn-secondary" onclick="return confirm('Create and send a QuickBooks Online invoice for this PO?');">Send QBO Invoice</button>
+    </form>
+    {% endif %}
+  {% endif %}
+
+  {% if purchase_order.qbo_invoice_url %}
+  <a href="{{ purchase_order.qbo_invoice_url }}" target="_blank" rel="noopener" class="btn btn-sm btn-secondary">View QBO Invoice</a>
+  {% endif %}
+
   {% if purchase_order.status != "cancelled" and purchase_order.status != "paid" %}
   <form method="post" action="{% url 'manage:purchase-order-cancel' conference.slug purchase_order.pk %}" style="display: inline;">
     {% csrf_token %}
diff --git a/src/django_program/manage/urls_purchase_orders.py b/src/django_program/manage/urls_purchase_orders.py
index 8abeb0b..41ec30b 100644
--- a/src/django_program/manage/urls_purchase_orders.py
+++ b/src/django_program/manage/urls_purchase_orders.py
@@ -10,10 +10,13 @@
     PurchaseOrderCancelView,
     PurchaseOrderCreateView,
     PurchaseOrderDetailView,
+    PurchaseOrderInvoiceView,
     PurchaseOrderIssueCreditView,
     PurchaseOrderListView,
+    PurchaseOrderQBOInvoiceView,
     PurchaseOrderRecordPaymentView,
     PurchaseOrderSendView,
+    PurchaseOrderStripeInvoiceView,
 )
 
 urlpatterns = [
@@ -24,4 +27,7 @@
     path("<int:pk>/credit/", PurchaseOrderIssueCreditView.as_view(), name="purchase-order-credit"),
     path("<int:pk>/cancel/", PurchaseOrderCancelView.as_view(), name="purchase-order-cancel"),
     path("<int:pk>/send/", PurchaseOrderSendView.as_view(), name="purchase-order-send"),
+    path("<int:pk>/invoice/", PurchaseOrderInvoiceView.as_view(), name="purchase-order-invoice"),
+    path("<int:pk>/stripe-invoice/", PurchaseOrderStripeInvoiceView.as_view(), name="purchase-order-stripe-invoice"),
+    path("<int:pk>/qbo-invoice/", PurchaseOrderQBOInvoiceView.as_view(), name="purchase-order-qbo-invoice"),
 ]
diff --git a/src/django_program/manage/views.py b/src/django_program/manage/views.py
index 156e9b8..d6032f0 100644
--- a/src/django_program/manage/views.py
+++ b/src/django_program/manage/views.py
@@ -33,7 +33,7 @@
 from django.views import View
 from django.views.generic import CreateView, DetailView, ListView, TemplateView, UpdateView
 
-from django_program.conference.models import Conference, Expense, ExpenseCategory, Section
+from django_program.conference.models import Conference, Expense, ExpenseCategory, KPITargets, Section
 from django_program.manage.forms import (
     ActivityForm,
     AddOnForm,
@@ -47,6 +47,7 @@
     GroupMemberConditionForm,
     ImportFromPretalxForm,
     IncludedProductConditionForm,
+    KPITargetsForm,
     ManualPaymentForm,
     ReceiptFlagForm,
     ReviewerMessageForm,
@@ -800,14 +801,26 @@ class ConferenceEditView(ManagePermissionMixin, UpdateView):
     form_class = ConferenceForm
     context_object_name = "conference"
 
+    def _get_kpi_instance(self) -> KPITargets | None:
+        """Return the existing KPITargets for this conference, or None."""
+        try:
+            return self.conference.kpi_targets  # type: ignore[return-value]
+        except KPITargets.DoesNotExist:
+            return None
+
     def get_context_data(self, **kwargs: object) -> dict[str, object]:
-        """Add ``active_nav`` to the template context.
+        """Add ``active_nav`` and KPI targets form to the template context.
 
         Returns:
             Context dict with sidebar active state set.
         """
         context = super().get_context_data(**kwargs)
         context["active_nav"] = "conference-edit"
+        if "kpi_form" not in context:
+            context["kpi_form"] = KPITargetsForm(
+                instance=self._get_kpi_instance(),
+                prefix="kpi",
+            )
         return context
 
     def get_object(self, queryset: QuerySet[Conference] | None = None) -> Conference:  # noqa: ARG002
@@ -826,6 +839,27 @@ def get_success_url(self) -> str:
         """
         return reverse("manage:dashboard", kwargs={"conference_slug": self.conference.slug})
 
+    def post(self, request: HttpRequest, *args: object, **kwargs: object) -> HttpResponse:  # noqa: ARG002
+        """Handle both the conference form and the KPI targets inline form."""
+        self.object = self.get_object()
+        form = self.get_form()
+        kpi_form = KPITargetsForm(
+            request.POST,
+            instance=self._get_kpi_instance(),
+            prefix="kpi",
+        )
+        if form.is_valid() and kpi_form.is_valid():
+            return self._forms_valid(form, kpi_form)
+        return self.render_to_response(self.get_context_data(form=form, kpi_form=kpi_form))
+
+    def _forms_valid(self, form: ConferenceForm, kpi_form: KPITargetsForm) -> HttpResponse:
+        """Save both the conference and KPI targets forms."""
+        response = super().form_valid(form)
+        kpi = kpi_form.save(commit=False)
+        kpi.conference = self.conference
+        kpi.save()
+        return response
+
     def form_valid(self, form: ConferenceForm) -> HttpResponse:
         """Save the form and add a success message.
 
diff --git a/src/django_program/manage/views_financial.py b/src/django_program/manage/views_financial.py
index e6a48e7..29747ee 100644
--- a/src/django_program/manage/views_financial.py
+++ b/src/django_program/manage/views_financial.py
@@ -38,6 +38,7 @@
     Payment,
     TicketType,
 )
+from django_program.registration.purchase_order import PurchaseOrder, PurchaseOrderPayment
 
 _ZERO = Decimal("0.00")
 
@@ -487,5 +488,68 @@ def get_context_data(self, **kwargs: object) -> dict[str, object]:  # noqa: PLR0
             }
         )
 
+        # --- Purchase Orders ---
+        po_qs = PurchaseOrder.objects.filter(conference=conference)
+        po_status_rows = po_qs.values("status").annotate(count=Count("id"), total=Coalesce(Sum("total"), Value(_ZERO)))
+        po_by_status: dict[str, dict[str, object]] = {
+            status_value: {"count": 0, "total": _ZERO} for status_value, _label in PurchaseOrder.Status.choices
+        }
+        for row in po_status_rows:
+            po_by_status[row["status"]] = {"count": row["count"], "total": row["total"] or _ZERO}
+        total_pos = sum(d["count"] for d in po_by_status.values())  # type: ignore[arg-type]
+
+        po_revenue = (
+            po_qs.filter(
+                status__in=[
+                    PurchaseOrder.Status.PAID,
+                    PurchaseOrder.Status.OVERPAID,
+                    PurchaseOrder.Status.PARTIALLY_PAID,
+                ]
+            ).aggregate(total=Sum("total"))["total"]
+            or _ZERO
+        )
+        po_collected = (
+            PurchaseOrderPayment.objects.filter(purchase_order__conference=conference).aggregate(total=Sum("amount"))[
+                "total"
+            ]
+            or _ZERO
+        )
+        po_balance = po_revenue - po_collected
+
+        context["po_by_status"] = po_by_status
+        context["total_pos"] = total_pos
+        context["po_revenue"] = po_revenue
+        context["po_collected"] = po_collected
+        context["po_balance_outstanding"] = po_balance
+
+        po_payment_rows = (
+            PurchaseOrderPayment.objects.filter(purchase_order__conference=conference)
+            .values("method")
+            .annotate(count=Count("id"), total=Coalesce(Sum("amount"), Value(_ZERO)))
+        )
+        po_method_labels = {v: str(label) for v, label in PurchaseOrderPayment.Method.choices}
+        po_payments_by_method: dict[str, dict[str, object]] = {
+            method_value: {"label": po_method_labels[method_value], "count": 0, "total": _ZERO}
+            for method_value in po_method_labels
+        }
+        for row in po_payment_rows:
+            po_payments_by_method[row["method"]] = {
+                "label": po_method_labels[row["method"]],
+                "count": row["count"],
+                "total": row["total"] or _ZERO,
+            }
+        context["po_payments_by_method"] = po_payments_by_method
+
+        recent_pos = po_qs.order_by("-created_at")[:10]
+        context["recent_pos"] = recent_pos
+
+        context["chart_po_json"] = json.dumps(
+            [
+                {"status": status, "count": data["count"], "total": float(data["total"])}
+                for status, data in po_by_status.items()
+                if data["count"] > 0
+            ]
+        )
+
         context["active_nav"] = "financial"
         return context
diff --git a/src/django_program/manage/views_purchase_orders.py b/src/django_program/manage/views_purchase_orders.py
index eb4237a..378053b 100644
--- a/src/django_program/manage/views_purchase_orders.py
+++ b/src/django_program/manage/views_purchase_orders.py
@@ -6,6 +6,7 @@
 from typing import TYPE_CHECKING
 
 from django.contrib import messages
+from django.http import HttpResponse
 from django.shortcuts import get_object_or_404, redirect
 from django.template.response import TemplateResponse
 from django.urls import reverse
@@ -23,14 +24,22 @@
 from django_program.registration.services.purchase_orders import (
     cancel_purchase_order,
     create_purchase_order,
+    generate_invoice_pdf,
     issue_credit_note,
     record_payment,
     send_purchase_order,
 )
+from django_program.registration.services.qbo_invoicing import (
+    QBOAPIError,
+    QBONotConfiguredError,
+    create_qbo_invoice,
+    send_qbo_invoice_email,
+)
+from django_program.registration.services.stripe_invoicing import create_stripe_invoice
 
 if TYPE_CHECKING:
     from django.db.models import QuerySet
-    from django.http import HttpRequest, HttpResponse
+    from django.http import HttpRequest
 
 logger = logging.getLogger(__name__)
 
@@ -359,3 +368,111 @@ def post(self, request: HttpRequest, **kwargs: str) -> HttpResponse:  # noqa: AR
 
         messages.success(request, f"Purchase order {po.reference} marked as sent.")
         return redirect(detail_url)
+
+
+class PurchaseOrderInvoiceView(ManagePermissionMixin, View):
+    """Generate and download a PO invoice as PDF."""
+
+    def get(self, request: HttpRequest, **kwargs: str) -> HttpResponse:  # noqa: ARG002
+        """Generate the invoice PDF and return it as a downloadable attachment."""
+        po = get_object_or_404(PurchaseOrder, pk=self.kwargs["pk"], conference=self.conference)
+        pdf_bytes = generate_invoice_pdf(po)
+        conf_slug = self.conference.slug
+        response = HttpResponse(pdf_bytes, content_type="application/pdf")
+        response["Content-Disposition"] = f'attachment; filename="{conf_slug}-invoice-{po.reference}.pdf"'
+        return response
+
+
+class PurchaseOrderStripeInvoiceView(ManagePermissionMixin, View):
+    """Create and send a Stripe Invoice for a purchase order (POST-only).
+
+    Uses the conference's Stripe keys to create a hosted invoice that the
+    customer can pay via card or ACH. Sets the PO status to SENT on success.
+    """
+
+    def post(self, request: HttpRequest, **kwargs: str) -> HttpResponse:  # noqa: ARG002
+        """Create a Stripe invoice and redirect back to the PO detail page."""
+        po = get_object_or_404(PurchaseOrder, pk=self.kwargs["pk"], conference=self.conference)
+        detail_url = reverse(
+            "manage:purchase-order-detail",
+            kwargs={"conference_slug": self.conference.slug, "pk": po.pk},
+        )
+
+        if po.status not in (PurchaseOrder.Status.DRAFT, PurchaseOrder.Status.SENT):
+            messages.error(
+                request,
+                f"Cannot send a Stripe invoice for a PO with status '{po.get_status_display()}'.",
+            )
+            return redirect(detail_url)
+
+        try:
+            hosted_url = create_stripe_invoice(po)
+        except ValueError as exc:
+            messages.error(request, str(exc))
+            return redirect(detail_url)
+        except Exception:
+            logger.exception("Failed to create Stripe invoice for PO %s", po.reference)
+            messages.error(request, "Failed to create Stripe invoice. Please try again.")
+            return redirect(detail_url)
+
+        if po.status == PurchaseOrder.Status.DRAFT:
+            po.status = PurchaseOrder.Status.SENT
+            po.save(update_fields=["status", "updated_at"])
+
+        messages.success(
+            request,
+            f"Stripe invoice sent for {po.reference}. Customer invoice URL: {hosted_url}",
+        )
+        return redirect(detail_url)
+
+
+class PurchaseOrderQBOInvoiceView(ManagePermissionMixin, View):
+    """Create and send a QuickBooks Online Invoice for a purchase order (POST-only).
+
+    Uses the conference's QBO credentials to create an invoice via the QBO
+    REST API and optionally emails it to the customer. Sets the PO status
+    to SENT on success if currently in draft.
+    """
+
+    def post(self, request: HttpRequest, **kwargs: str) -> HttpResponse:  # noqa: ARG002
+        """Create a QBO invoice and redirect back to the PO detail page."""
+        po = get_object_or_404(PurchaseOrder, pk=self.kwargs["pk"], conference=self.conference)
+        detail_url = reverse(
+            "manage:purchase-order-detail",
+            kwargs={"conference_slug": self.conference.slug, "pk": po.pk},
+        )
+
+        error_msg = self._validate_po_for_qbo(po)
+        if error_msg:
+            messages.error(request, error_msg) if "already" not in error_msg else messages.warning(request, error_msg)
+            return redirect(detail_url)
+
+        try:
+            create_qbo_invoice(po)
+            send_qbo_invoice_email(po)
+        except QBONotConfiguredError:
+            messages.error(request, "QuickBooks Online is not configured for this conference.")
+            return redirect(detail_url)
+        except (QBOAPIError, ValueError) as exc:
+            messages.error(request, f"QBO invoice failed: {exc}")
+            return redirect(detail_url)
+        except Exception:
+            logger.exception("Failed to create/send QBO invoice for PO %s", po.reference)
+            messages.error(request, "Failed to create QBO invoice. Please try again.")
+            return redirect(detail_url)
+
+        if po.status == PurchaseOrder.Status.DRAFT:
+            po.status = PurchaseOrder.Status.SENT
+            po.save(update_fields=["status", "updated_at"])
+
+        messages.success(request, f"QBO invoice created and sent for {po.reference}.")
+        return redirect(detail_url)
+
+    @staticmethod
+    def _validate_po_for_qbo(po: PurchaseOrder) -> str:
+        """Return an error message if the PO cannot have a QBO invoice created, or empty string."""
+        if po.status not in (PurchaseOrder.Status.DRAFT, PurchaseOrder.Status.SENT):
+            return f"Cannot send a QBO invoice for a PO with status '{po.get_status_display()}'."
+        if po.qbo_invoice_id:
+            return f"PO {po.reference} already has a QBO invoice."
+        return ""
diff --git a/src/django_program/registration/migrations/0021_add_qbo_invoice_fields.py b/src/django_program/registration/migrations/0021_add_qbo_invoice_fields.py
new file mode 100644
index 0000000..0b72d33
--- /dev/null
+++ b/src/django_program/registration/migrations/0021_add_qbo_invoice_fields.py
@@ -0,0 +1,49 @@
+# Generated by Django 5.2.11 on 2026-03-19 18:36
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("program_registration", "0020_purchaseorder_purchaseordercreditnote_and_more"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="purchaseorder",
+            name="qbo_invoice_id",
+            field=models.CharField(
+                blank=True,
+                default="",
+                help_text="QuickBooks Online Invoice ID, set after invoice creation.",
+                max_length=200,
+            ),
+        ),
+        migrations.AddField(
+            model_name="purchaseorder",
+            name="qbo_invoice_url",
+            field=models.URLField(
+                blank=True, default="", help_text="Public URL to the QBO invoice for the customer.", max_length=500
+            ),
+        ),
+        migrations.AddField(
+            model_name="purchaseorder",
+            name="stripe_invoice_id",
+            field=models.CharField(
+                blank=True,
+                default="",
+                help_text="Stripe Invoice ID (e.g. in_xxx) when sent via Stripe Invoicing.",
+                max_length=200,
+            ),
+        ),
+        migrations.AddField(
+            model_name="purchaseorder",
+            name="stripe_invoice_url",
+            field=models.URLField(
+                blank=True,
+                default="",
+                help_text="Stripe-hosted invoice URL for the customer to pay online.",
+                max_length=500,
+            ),
+        ),
+    ]
diff --git a/src/django_program/registration/purchase_order.py b/src/django_program/registration/purchase_order.py
index b51a44f..dc05aef 100644
--- a/src/django_program/registration/purchase_order.py
+++ b/src/django_program/registration/purchase_order.py
@@ -44,6 +44,30 @@ class Status(models.TextChoices):
         choices=Status.choices,
         default=Status.DRAFT,
     )
+    stripe_invoice_id = models.CharField(
+        max_length=200,
+        blank=True,
+        default="",
+        help_text="Stripe Invoice ID (e.g. in_xxx) when sent via Stripe Invoicing.",
+    )
+    stripe_invoice_url = models.URLField(
+        max_length=500,
+        blank=True,
+        default="",
+        help_text="Stripe-hosted invoice URL for the customer to pay online.",
+    )
+    qbo_invoice_id = models.CharField(
+        max_length=200,
+        blank=True,
+        default="",
+        help_text="QuickBooks Online Invoice ID, set after invoice creation.",
+    )
+    qbo_invoice_url = models.URLField(
+        max_length=500,
+        blank=True,
+        default="",
+        help_text="Public URL to the QBO invoice for the customer.",
+    )
     notes = models.TextField(blank=True, default="")
     reference = models.CharField(
         max_length=100,
diff --git a/src/django_program/registration/services/purchase_orders.py b/src/django_program/registration/services/purchase_orders.py
index 5023463..2a54c0d 100644
--- a/src/django_program/registration/services/purchase_orders.py
+++ b/src/django_program/registration/services/purchase_orders.py
@@ -1,10 +1,11 @@
 """Service layer for purchase order lifecycle management.
 
 Handles PO creation, payment recording, credit note issuance, status
-transitions, and cancellation. All state-mutating functions use atomic
-transactions to maintain consistency.
+transitions, cancellation, and invoice PDF generation. All state-mutating
+functions use atomic transactions to maintain consistency.
 """
 
+import io
 import logging
 import secrets
 import string
@@ -12,6 +13,7 @@
 from typing import TYPE_CHECKING
 
 from django.db import transaction
+from django.utils import timezone
 
 from django_program.registration.purchase_order import (
     PurchaseOrder,
@@ -306,3 +308,342 @@ def cancel_purchase_order(purchase_order: PurchaseOrder) -> None:
     purchase_order.status = PurchaseOrder.Status.CANCELLED
     purchase_order.save(update_fields=["status", "updated_at"])
     logger.info("Cancelled purchase order %s", purchase_order.reference)
+
+
+def generate_invoice_pdf(purchase_order: PurchaseOrder) -> bytes:
+    """Generate a professional invoice PDF for a purchase order.
+
+    Produces a PDF with conference letterhead, billing details, line items,
+    financial summary, and payment history. Uses the same reportlab pattern
+    as the invitation letter generator.
+
+    Args:
+        purchase_order: The purchase order to generate an invoice for.
+
+    Returns:
+        The raw PDF bytes.
+    """
+    from reportlab.lib.pagesizes import A4  # noqa: PLC0415
+    from reportlab.lib.units import mm  # noqa: PLC0415
+    from reportlab.pdfgen import canvas  # noqa: PLC0415
+
+    buf = io.BytesIO()
+    width, height = A4
+    c = canvas.Canvas(buf, pagesize=A4)
+    margin = 25 * mm
+    usable_width = width - 2 * margin
+
+    conference = purchase_order.conference
+
+    y = _draw_invoice_letterhead(c, conference, margin, height - margin, width)
+    y = _draw_invoice_title(c, purchase_order, margin, y)
+    y = _draw_bill_to(c, purchase_order, margin, y)
+    y = _draw_line_items_table(c, purchase_order, margin, y, usable_width)
+    y = _draw_financial_summary(c, purchase_order, margin, y, usable_width)
+    y = _draw_payment_history(c, purchase_order, margin, y, usable_width)
+    _draw_invoice_footer(c, conference, margin, y, width)
+
+    c.showPage()
+    c.save()
+    return buf.getvalue()
+
+
+def _draw_invoice_letterhead(c: object, conference: object, margin: float, y: float, width: float) -> float:
+    """Draw conference letterhead at the top of the invoice.
+
+    Args:
+        c: The reportlab Canvas instance.
+        conference: The conference model instance.
+        margin: Left margin in points.
+        y: Current y position.
+        width: Page width in points.
+
+    Returns:
+        Updated y position after the letterhead.
+    """
+    from reportlab.lib.units import mm  # noqa: PLC0415
+
+    c.setFont("Helvetica-Bold", 16)  # type: ignore[attr-defined]
+    c.drawString(margin, y, str(conference.name))  # type: ignore[attr-defined]
+    y -= 7 * mm
+
+    if conference.venue or conference.address:
+        c.setFont("Helvetica", 10)  # type: ignore[attr-defined]
+        venue_line = ", ".join(filter(None, [str(conference.venue), str(conference.address)]))
+        c.drawString(margin, y, venue_line)  # type: ignore[attr-defined]
+        y -= 5 * mm
+
+    if conference.website_url:
+        c.setFont("Helvetica", 9)  # type: ignore[attr-defined]
+        c.drawString(margin, y, str(conference.website_url))  # type: ignore[attr-defined]
+        y -= 5 * mm
+
+    y -= 5 * mm
+    c.setStrokeColorRGB(0.7, 0.7, 0.7)  # type: ignore[attr-defined]
+    c.line(margin, y, width - margin, y)  # type: ignore[attr-defined]
+    y -= 10 * mm
+
+    return y
+
+
+def _draw_invoice_title(c: object, purchase_order: PurchaseOrder, margin: float, y: float) -> float:
+    """Draw the invoice title and date.
+
+    Args:
+        c: The reportlab Canvas instance.
+        purchase_order: The purchase order.
+        margin: Left margin in points.
+        y: Current y position.
+
+    Returns:
+        Updated y position after the title block.
+    """
+    from reportlab.lib.units import mm  # noqa: PLC0415
+
+    c.setFont("Helvetica-Bold", 18)  # type: ignore[attr-defined]
+    c.drawString(margin, y, f"INVOICE {purchase_order.reference}")  # type: ignore[attr-defined]
+    y -= 8 * mm
+
+    c.setFont("Helvetica", 10)  # type: ignore[attr-defined]
+    today_str = timezone.now().strftime("%B %d, %Y")
+    c.drawString(margin, y, f"Date: {today_str}")  # type: ignore[attr-defined]
+    y -= 5 * mm
+
+    c.drawString(margin, y, f"Status: {purchase_order.get_status_display()}")  # type: ignore[attr-defined]
+    y -= 10 * mm
+
+    return y
+
+
+def _draw_bill_to(c: object, purchase_order: PurchaseOrder, margin: float, y: float) -> float:
+    """Draw the Bill To section with organization and contact details.
+
+    Args:
+        c: The reportlab Canvas instance.
+        purchase_order: The purchase order.
+        margin: Left margin in points.
+        y: Current y position.
+
+    Returns:
+        Updated y position after the billing section.
+    """
+    from reportlab.lib.units import mm  # noqa: PLC0415
+
+    c.setFont("Helvetica-Bold", 11)  # type: ignore[attr-defined]
+    c.drawString(margin, y, "Bill To:")  # type: ignore[attr-defined]
+    y -= 6 * mm
+
+    c.setFont("Helvetica", 10)  # type: ignore[attr-defined]
+    c.drawString(margin + 5 * mm, y, str(purchase_order.organization_name))  # type: ignore[attr-defined]
+    y -= 5 * mm
+
+    if purchase_order.contact_name:
+        c.drawString(margin + 5 * mm, y, str(purchase_order.contact_name))  # type: ignore[attr-defined]
+        y -= 5 * mm
+
+    c.drawString(margin + 5 * mm, y, str(purchase_order.contact_email))  # type: ignore[attr-defined]
+    y -= 5 * mm
+
+    if purchase_order.billing_address:
+        for addr_line in str(purchase_order.billing_address).split("\n"):
+            stripped = addr_line.strip()
+            if stripped:
+                c.drawString(margin + 5 * mm, y, stripped)  # type: ignore[attr-defined]
+                y -= 5 * mm
+
+    y -= 8 * mm
+    return y
+
+
+def _draw_line_items_table(
+    c: object, purchase_order: PurchaseOrder, margin: float, y: float, usable_width: float
+) -> float:
+    """Draw the line items table with headers and rows.
+
+    Args:
+        c: The reportlab Canvas instance.
+        purchase_order: The purchase order.
+        margin: Left margin in points.
+        y: Current y position.
+        usable_width: Available text width in points.
+
+    Returns:
+        Updated y position after the table.
+    """
+    from reportlab.lib.units import mm  # noqa: PLC0415
+
+    col_desc_x = margin
+    col_qty_x = margin + usable_width * 0.55
+    col_price_x = margin + usable_width * 0.70
+    col_total_x = margin + usable_width * 0.85
+
+    c.setFont("Helvetica-Bold", 10)  # type: ignore[attr-defined]
+    c.drawString(col_desc_x, y, "Description")  # type: ignore[attr-defined]
+    c.drawRightString(col_qty_x + 30, y, "Qty")  # type: ignore[attr-defined]
+    c.drawRightString(col_price_x + 40, y, "Unit Price")  # type: ignore[attr-defined]
+    c.drawRightString(col_total_x + 40, y, "Line Total")  # type: ignore[attr-defined]
+    y -= 3 * mm
+
+    c.setStrokeColorRGB(0.7, 0.7, 0.7)  # type: ignore[attr-defined]
+    c.line(margin, y, margin + usable_width, y)  # type: ignore[attr-defined]
+    y -= 5 * mm
+
+    c.setFont("Helvetica", 10)  # type: ignore[attr-defined]
+    line_items = purchase_order.line_items.all()
+    for item in line_items:
+        desc_text = str(item.description)
+        wrapped = _invoice_wrap_text(c, desc_text, "Helvetica", 10, usable_width * 0.52)
+        for i, segment in enumerate(wrapped):
+            c.drawString(col_desc_x, y, segment)  # type: ignore[attr-defined]
+            if i == 0:
+                c.drawRightString(col_qty_x + 30, y, str(item.quantity))  # type: ignore[attr-defined]
+                c.drawRightString(col_price_x + 40, y, f"${item.unit_price}")  # type: ignore[attr-defined]
+                c.drawRightString(col_total_x + 40, y, f"${item.line_total}")  # type: ignore[attr-defined]
+            y -= 5 * mm
+
+    y -= 3 * mm
+    c.setStrokeColorRGB(0.7, 0.7, 0.7)  # type: ignore[attr-defined]
+    c.line(margin, y, margin + usable_width, y)  # type: ignore[attr-defined]
+    y -= 6 * mm
+
+    return y
+
+
+def _draw_financial_summary(
+    c: object, purchase_order: PurchaseOrder, margin: float, y: float, usable_width: float
+) -> float:
+    """Draw the financial summary (subtotal, total, paid, credits, balance).
+
+    Args:
+        c: The reportlab Canvas instance.
+        purchase_order: The purchase order.
+        margin: Left margin in points.
+        y: Current y position.
+        usable_width: Available text width in points.
+
+    Returns:
+        Updated y position after the summary.
+    """
+    from reportlab.lib.units import mm  # noqa: PLC0415
+
+    value_x = margin + usable_width * 0.85 + 40
+
+    summary_lines: list[tuple[str, str, str, bool]] = [
+        ("Subtotal:", f"${purchase_order.subtotal}", "Helvetica", False),
+        ("Total:", f"${purchase_order.total}", "Helvetica-Bold", False),
+        ("Total Paid:", f"${purchase_order.total_paid}", "Helvetica", False),
+    ]
+
+    total_credited = purchase_order.total_credited
+    if total_credited:
+        summary_lines.append(("Total Credits:", f"${total_credited}", "Helvetica", False))
+
+    summary_lines.append(("Balance Due:", f"${purchase_order.balance_due}", "Helvetica-Bold", True))
+
+    for label, value, font, is_large in summary_lines:
+        size = 12 if is_large else 10
+        c.setFont(font, size)  # type: ignore[attr-defined]
+        c.drawRightString(value_x - 50, y, label)  # type: ignore[attr-defined]
+        c.drawRightString(value_x, y, value)  # type: ignore[attr-defined]
+        y -= 6 * mm
+
+    y -= 4 * mm
+    return y
+
+
+def _draw_payment_history(
+    c: object, purchase_order: PurchaseOrder, margin: float, y: float, usable_width: float
+) -> float:
+    """Draw the payment history section.
+
+    Args:
+        c: The reportlab Canvas instance.
+        purchase_order: The purchase order.
+        margin: Left margin in points.
+        y: Current y position.
+        usable_width: Available text width in points.
+
+    Returns:
+        Updated y position after the payment history.
+    """
+    from reportlab.lib.units import mm  # noqa: PLC0415
+
+    payments = purchase_order.payments.all()
+    if not payments:
+        return y
+
+    c.setFont("Helvetica-Bold", 11)  # type: ignore[attr-defined]
+    c.drawString(margin, y, "Payment History")  # type: ignore[attr-defined]
+    y -= 6 * mm
+
+    c.setStrokeColorRGB(0.7, 0.7, 0.7)  # type: ignore[attr-defined]
+    c.line(margin, y, margin + usable_width, y)  # type: ignore[attr-defined]
+    y -= 5 * mm
+
+    c.setFont("Helvetica", 9)  # type: ignore[attr-defined]
+    for payment in payments:
+        date_str = payment.payment_date.strftime("%b %d, %Y")
+        method_str = payment.get_method_display()
+        ref_str = f" (ref: {payment.reference})" if payment.reference else ""
+        line = f"{date_str}  —  {method_str}  —  ${payment.amount}{ref_str}"
+        c.drawString(margin, y, line)  # type: ignore[attr-defined]
+        y -= 5 * mm
+
+    y -= 4 * mm
+    return y
+
+
+def _draw_invoice_footer(c: object, conference: object, margin: float, _y: float, width: float) -> None:
+    """Draw the invoice footer with generation date and conference name.
+
+    Args:
+        c: The reportlab Canvas instance.
+        conference: The conference model instance.
+        margin: Left margin in points.
+        _y: Current y position (accepted for calling convention; footer draws at fixed position).
+        width: Page width in points.
+    """
+    from reportlab.lib.units import mm  # noqa: PLC0415
+
+    footer_y = 20 * mm
+
+    c.setStrokeColorRGB(0.85, 0.85, 0.85)  # type: ignore[attr-defined]
+    c.line(margin, footer_y + 5 * mm, width - margin, footer_y + 5 * mm)  # type: ignore[attr-defined]
+
+    c.setFont("Helvetica", 8)  # type: ignore[attr-defined]
+    today_str = timezone.now().strftime("%B %d, %Y")
+    c.drawString(margin, footer_y, f"Generated on {today_str}")  # type: ignore[attr-defined]
+    c.drawRightString(width - margin, footer_y, str(conference.name))  # type: ignore[attr-defined]
+
+
+def _invoice_wrap_text(canvas_obj: object, text: str, font: str, size: int, max_width: float) -> list[str]:
+    """Wrap text to fit within a given width on a reportlab canvas.
+
+    Args:
+        canvas_obj: The reportlab Canvas instance.
+        text: The text to wrap.
+        font: Font name for width calculation.
+        size: Font size in points.
+        max_width: Maximum line width in points.
+
+    Returns:
+        A list of text segments, each fitting within ``max_width``.
+    """
+    words = text.split()
+    lines: list[str] = []
+    current_line = ""
+
+    for word in words:
+        test_line = f"{current_line} {word}".strip() if current_line else word
+        tw = canvas_obj.stringWidth(test_line, font, size)  # type: ignore[attr-defined]
+        if tw <= max_width:
+            current_line = test_line
+        else:
+            if current_line:
+                lines.append(current_line)
+            current_line = word
+
+    if current_line:
+        lines.append(current_line)
+
+    return lines or [""]
diff --git a/src/django_program/registration/services/qbo_invoicing.py b/src/django_program/registration/services/qbo_invoicing.py
new file mode 100644
index 0000000..707ceda
--- /dev/null
+++ b/src/django_program/registration/services/qbo_invoicing.py
@@ -0,0 +1,566 @@
+"""QuickBooks Online invoicing integration for purchase orders.
+
+Provides functions to create and sync QBO invoices from purchase orders,
+using the QBO REST API v3 directly via httpx. Handles OAuth2 token refresh
+transparently so callers only need a Conference with valid QBO credentials.
+
+The QBO OAuth flow for obtaining initial tokens is out of scope -- tokens
+are assumed to be stored on the Conference model and refreshed here when
+expired.
+"""
+
+import base64
+import logging
+from http import HTTPStatus
+from typing import TYPE_CHECKING
+
+import httpx
+from django.utils import timezone
+
+if TYPE_CHECKING:
+    from django_program.conference.models import Conference
+    from django_program.registration.purchase_order import PurchaseOrder
+
+logger = logging.getLogger(__name__)
+
+QBO_BASE_URL = "https://quickbooks.api.intuit.com"
+QBO_SANDBOX_BASE_URL = "https://sandbox-quickbooks.api.intuit.com"
+QBO_TOKEN_ENDPOINT = "https://oauth.platform.intuit.com/oauth2/v1/tokens/bearer"  # noqa: S105
+
+_REQUEST_TIMEOUT = 30.0
+
+
+class QBONotConfiguredError(ValueError):
+    """Raised when a conference does not have QBO credentials configured."""
+
+
+class QBOAPIError(Exception):
+    """Raised when the QBO API returns an error response.
+
+    Args:
+        status_code: The HTTP status code from the QBO API.
+        detail: A description of the error.
+    """
+
+    def __init__(self, status_code: int, detail: str) -> None:
+        """Initialize with the HTTP status code and error detail."""
+        self.status_code = status_code
+        self.detail = detail
+        super().__init__(f"QBO API error {status_code}: {detail}")
+
+
+def _check_response(response: httpx.Response) -> None:
+    """Raise ``QBOAPIError`` if the response is not HTTP 200.
+
+    Args:
+        response: The httpx response to check.
+
+    Raises:
+        QBOAPIError: If the status code is not 200.
+    """
+    if response.status_code != HTTPStatus.OK:
+        raise QBOAPIError(response.status_code, response.text)
+
+
+def _ensure_qbo_configured(conference: Conference) -> None:
+    """Validate that a conference has the required QBO credentials.
+
+    Args:
+        conference: The conference to validate.
+
+    Raises:
+        QBONotConfiguredError: If QBO credentials are missing.
+    """
+    realm_id = str(conference.qbo_realm_id or "")
+    access_token = str(conference.qbo_access_token or "")
+    if not realm_id or not access_token:
+        msg = (
+            f"Conference '{conference.slug}' does not have QuickBooks Online configured. "
+            f"Set qbo_realm_id and qbo_access_token on the Conference record."
+        )
+        raise QBONotConfiguredError(msg)
+
+
+def _refresh_token_if_needed(conference: Conference) -> str:
+    """Return a valid QBO access token, refreshing if expired.
+
+    Checks ``qbo_token_expires_at`` and uses the refresh token + client
+    credentials to obtain a new access token when the current one has
+    expired or is about to expire (within 5 minutes).
+
+    Args:
+        conference: The conference whose tokens to check/refresh.
+
+    Returns:
+        A valid access token string.
+
+    Raises:
+        QBONotConfiguredError: If credentials are missing.
+        QBOAPIError: If the token refresh request fails.
+    """
+    _ensure_qbo_configured(conference)
+
+    access_token = str(conference.qbo_access_token or "")
+    expires_at = conference.qbo_token_expires_at
+    now = timezone.now()
+
+    # If token is still valid (with 5-minute buffer), return it directly
+    if expires_at is not None and expires_at > now + timezone.timedelta(minutes=5):
+        return access_token
+
+    refresh_token = str(conference.qbo_refresh_token or "")
+    client_id = str(conference.qbo_client_id or "")
+    client_secret = str(conference.qbo_client_secret or "")
+
+    if not refresh_token or not client_id or not client_secret:
+        logger.warning(
+            "QBO token may be expired for conference '%s' but refresh credentials are incomplete",
+            conference.slug,
+        )
+        return access_token
+
+    logger.info("Refreshing QBO access token for conference '%s'", conference.slug)
+
+    auth_header = base64.b64encode(f"{client_id}:{client_secret}".encode()).decode()
+    response = httpx.post(
+        QBO_TOKEN_ENDPOINT,
+        headers={
+            "Authorization": f"Basic {auth_header}",
+            "Content-Type": "application/x-www-form-urlencoded",
+            "Accept": "application/json",
+        },
+        data={
+            "grant_type": "refresh_token",
+            "refresh_token": refresh_token,
+        },
+        timeout=_REQUEST_TIMEOUT,
+    )
+
+    _check_response(response)
+
+    token_data = response.json()
+    new_access_token = token_data["access_token"]
+    new_refresh_token = token_data.get("refresh_token", refresh_token)
+    expires_in = int(token_data.get("expires_in", 3600))
+
+    conference.qbo_access_token = new_access_token
+    conference.qbo_refresh_token = new_refresh_token
+    conference.qbo_token_expires_at = now + timezone.timedelta(seconds=expires_in)
+    conference.save(
+        update_fields=[
+            "qbo_access_token",
+            "qbo_refresh_token",
+            "qbo_token_expires_at",
+            "updated_at",
+        ]
+    )
+
+    logger.info("QBO token refreshed for conference '%s', expires in %ds", conference.slug, expires_in)
+    return new_access_token
+
+
+def _qbo_api_url(conference: Conference, endpoint: str) -> str:
+    """Build the full QBO API URL for a given endpoint.
+
+    Args:
+        conference: The conference (provides realm_id).
+        endpoint: The API endpoint path (e.g. ``"invoice"``).
+
+    Returns:
+        The full URL string.
+    """
+    realm_id = str(conference.qbo_realm_id)
+    return f"{QBO_BASE_URL}/v3/company/{realm_id}/{endpoint}"
+
+
+def _qbo_headers(access_token: str) -> dict[str, str]:
+    """Build standard QBO API request headers.
+
+    Args:
+        access_token: A valid OAuth2 access token.
+
+    Returns:
+        Headers dict with authorization and content type.
+    """
+    return {
+        "Authorization": f"Bearer {access_token}",
+        "Content-Type": "application/json",
+        "Accept": "application/json",
+    }
+
+
+def _build_billing_address(billing_address: str) -> dict[str, str]:
+    """Parse a multiline billing address into a QBO BillAddr dict.
+
+    Args:
+        billing_address: Multiline billing address text.
+
+    Returns:
+        A dict suitable for the QBO ``BillAddr`` field.
+    """
+    lines = billing_address.strip().splitlines()
+    bill_addr: dict[str, str] = {}
+    if lines:
+        bill_addr["Line1"] = lines[0]
+    if len(lines) > 1:
+        bill_addr["Line2"] = lines[1]
+    if len(lines) > 2:  # noqa: PLR2004
+        bill_addr["City"] = lines[2]
+    return bill_addr
+
+
+def _find_or_create_customer(
+    conference: Conference,
+    access_token: str,
+    *,
+    display_name: str,
+    email: str,
+    billing_address: str = "",
+) -> str:
+    """Find an existing QBO customer by display name, or create one.
+
+    Args:
+        conference: The conference for API context.
+        access_token: Valid QBO access token.
+        display_name: The customer display name (organization name).
+        email: Contact email address.
+        billing_address: Optional billing address text.
+
+    Returns:
+        The QBO Customer ID as a string.
+
+    Raises:
+        QBOAPIError: If the API request fails.
+    """
+    headers = _qbo_headers(access_token)
+
+    # Query for existing customer by display name (QBO query language, not SQL)
+    safe_name = display_name.replace("'", "\\'")
+    query_url = _qbo_api_url(conference, "query")
+    query = f"SELECT * FROM Customer WHERE DisplayName = '{safe_name}' MAXRESULTS 1"  # noqa: S608
+    response = httpx.get(
+        query_url,
+        headers=headers,
+        params={"query": query},
+        timeout=_REQUEST_TIMEOUT,
+    )
+
+    _check_response(response)
+
+    data = response.json()
+    customers = data.get("QueryResponse", {}).get("Customer", [])
+    if customers:
+        return str(customers[0]["Id"])
+
+    # Create a new customer
+    customer_payload: dict[str, object] = {
+        "DisplayName": display_name,
+        "PrimaryEmailAddr": {"Address": email},
+    }
+    if billing_address:
+        customer_payload["BillAddr"] = _build_billing_address(billing_address)
+
+    create_url = _qbo_api_url(conference, "customer")
+    response = httpx.post(
+        create_url,
+        headers=headers,
+        json=customer_payload,
+        timeout=_REQUEST_TIMEOUT,
+    )
+
+    _check_response(response)
+
+    created = response.json().get("Customer", {})
+    customer_id = str(created.get("Id", ""))
+    if not customer_id:
+        msg = "QBO returned a customer without an Id"
+        raise QBOAPIError(HTTPStatus.OK, msg)
+
+    logger.info("Created QBO customer '%s' (ID: %s) for conference '%s'", display_name, customer_id, conference.slug)
+    return customer_id
+
+
+def _build_invoice_lines(purchase_order: PurchaseOrder) -> list[dict[str, object]]:
+    """Build QBO invoice line items from a purchase order's line items.
+
+    Args:
+        purchase_order: The PO whose line items to convert.
+
+    Returns:
+        A list of QBO-formatted line item dicts.
+    """
+    from django_program.registration.purchase_order import PurchaseOrderLineItem  # noqa: PLC0415
+
+    po_lines = PurchaseOrderLineItem.objects.filter(purchase_order=purchase_order)
+    return [
+        {
+            "Amount": float(line.line_total),
+            "DetailType": "SalesItemLineDetail",
+            "Description": str(line.description),
+            "SalesItemLineDetail": {
+                "Qty": line.quantity,
+                "UnitPrice": float(line.unit_price),
+            },
+        }
+        for line in po_lines
+    ]
+
+
+def create_qbo_invoice(purchase_order: PurchaseOrder) -> str:
+    """Create a QBO Invoice from a purchase order's line items.
+
+    Finds or creates the QBO Customer by organization name, then builds
+    and submits an invoice with the PO's line items. Stores the resulting
+    QBO invoice ID and public URL on the PurchaseOrder.
+
+    Args:
+        purchase_order: The purchase order to invoice.
+
+    Returns:
+        The QBO invoice ID string.
+
+    Raises:
+        QBONotConfiguredError: If the conference lacks QBO credentials.
+        QBOAPIError: If any QBO API call fails.
+        ValueError: If the PO already has a QBO invoice.
+    """
+    if purchase_order.qbo_invoice_id:
+        msg = f"PO {purchase_order.reference} already has QBO invoice {purchase_order.qbo_invoice_id}"
+        raise ValueError(msg)
+
+    conference = purchase_order.conference
+    access_token = _refresh_token_if_needed(conference)
+
+    customer_id = _find_or_create_customer(
+        conference,
+        access_token,
+        display_name=str(purchase_order.organization_name),
+        email=str(purchase_order.contact_email),
+        billing_address=str(purchase_order.billing_address),
+    )
+
+    invoice_lines = _build_invoice_lines(purchase_order)
+
+    invoice_payload: dict[str, object] = {
+        "CustomerRef": {"value": customer_id},
+        "Line": invoice_lines,
+        "CustomerMemo": {"value": f"Purchase Order {purchase_order.reference}"},
+        "PrivateNote": f"django-program PO {purchase_order.reference}",
+    }
+
+    if purchase_order.contact_email:
+        invoice_payload["BillEmail"] = {"Address": str(purchase_order.contact_email)}
+
+    headers = _qbo_headers(access_token)
+    create_url = _qbo_api_url(conference, "invoice")
+    response = httpx.post(
+        create_url,
+        headers=headers,
+        json=invoice_payload,
+        timeout=_REQUEST_TIMEOUT,
+    )
+
+    _check_response(response)
+
+    invoice_data = response.json().get("Invoice", {})
+    invoice_id = str(invoice_data.get("Id", ""))
+    if not invoice_id:
+        msg = "QBO returned an invoice without an Id"
+        raise QBOAPIError(HTTPStatus.OK, msg)
+
+    # Build the customer-facing invoice URL
+    realm_id = str(conference.qbo_realm_id)
+    invoice_url = f"https://app.qbo.intuit.com/app/invoice?txnId={invoice_id}&companyId={realm_id}"
+
+    purchase_order.qbo_invoice_id = invoice_id
+    purchase_order.qbo_invoice_url = invoice_url
+    purchase_order.save(update_fields=["qbo_invoice_id", "qbo_invoice_url", "updated_at"])
+
+    logger.info(
+        "Created QBO invoice %s for PO %s (conference '%s')",
+        invoice_id,
+        purchase_order.reference,
+        conference.slug,
+    )
+    return invoice_id
+
+
+def sync_qbo_invoice_status(purchase_order: PurchaseOrder) -> None:
+    """Fetch the current QBO invoice status and record payment if paid.
+
+    Queries the QBO invoice by ID, checks its ``Balance`` field, and if
+    the invoice is fully paid (balance == 0), records a payment on the PO
+    using the existing ``record_payment()`` service function.
+
+    Args:
+        purchase_order: The PO whose QBO invoice to sync.
+
+    Raises:
+        ValueError: If the PO has no QBO invoice ID.
+        QBONotConfiguredError: If the conference lacks QBO credentials.
+        QBOAPIError: If the QBO API call fails.
+    """
+    if not purchase_order.qbo_invoice_id:
+        msg = f"PO {purchase_order.reference} has no QBO invoice to sync"
+        raise ValueError(msg)
+
+    conference = purchase_order.conference
+    access_token = _refresh_token_if_needed(conference)
+    headers = _qbo_headers(access_token)
+
+    invoice_url = _qbo_api_url(conference, f"invoice/{purchase_order.qbo_invoice_id}")
+    response = httpx.get(invoice_url, headers=headers, timeout=_REQUEST_TIMEOUT)
+
+    _check_response(response)
+
+    invoice_data = response.json().get("Invoice", {})
+    balance = float(invoice_data.get("Balance", -1))
+    total_amt = float(invoice_data.get("TotalAmt", 0))
+
+    if balance == 0 and total_amt > 0:
+        _record_qbo_payment(purchase_order, total_amt)
+    else:
+        logger.info(
+            "QBO invoice %s for PO %s has balance %.2f (not yet fully paid)",
+            purchase_order.qbo_invoice_id,
+            purchase_order.reference,
+            balance,
+        )
+
+
+def _record_qbo_payment(purchase_order: PurchaseOrder, total_amt: float) -> None:
+    """Record a QBO payment on a purchase order if not already fully paid.
+
+    Args:
+        purchase_order: The PO to record payment for.
+        total_amt: The total invoice amount from QBO.
+    """
+    from decimal import Decimal  # noqa: PLC0415
+
+    from django_program.registration.services.purchase_orders import record_payment  # noqa: PLC0415
+
+    already_paid = purchase_order.total_paid
+    payment_amount = Decimal(str(total_amt)) - already_paid
+
+    if payment_amount > 0:
+        record_payment(
+            purchase_order,
+            amount=payment_amount,
+            method="wire",
+            reference=f"QBO Invoice #{purchase_order.qbo_invoice_id}",
+            payment_date=timezone.now().date(),
+            note="Auto-recorded from QBO invoice payment sync.",
+        )
+        logger.info(
+            "Recorded QBO payment of %s for PO %s",
+            payment_amount,
+            purchase_order.reference,
+        )
+
+
+def send_qbo_invoice_email(purchase_order: PurchaseOrder) -> None:
+    """Send the QBO invoice to the customer via QBO's email delivery.
+
+    Uses the QBO ``invoice/{id}/send`` endpoint to trigger email delivery
+    to the billing email address stored on the invoice.
+
+    Args:
+        purchase_order: The PO whose QBO invoice to send.
+
+    Raises:
+        ValueError: If the PO has no QBO invoice ID.
+        QBONotConfiguredError: If the conference lacks QBO credentials.
+        QBOAPIError: If the QBO API call fails.
+    """
+    if not purchase_order.qbo_invoice_id:
+        msg = f"PO {purchase_order.reference} has no QBO invoice to send"
+        raise ValueError(msg)
+
+    conference = purchase_order.conference
+    access_token = _refresh_token_if_needed(conference)
+    headers = _qbo_headers(access_token)
+
+    send_url = _qbo_api_url(conference, f"invoice/{purchase_order.qbo_invoice_id}/send")
+    params: dict[str, str] = {}
+    if purchase_order.contact_email:
+        params["sendTo"] = str(purchase_order.contact_email)
+
+    response = httpx.post(send_url, headers=headers, params=params, timeout=_REQUEST_TIMEOUT)
+
+    _check_response(response)
+
+    logger.info(
+        "Sent QBO invoice %s via email for PO %s",
+        purchase_order.qbo_invoice_id,
+        purchase_order.reference,
+    )
+
+
+def handle_qbo_webhook(payload: dict[str, object]) -> None:
+    """Process a QBO webhook notification for invoice payment events.
+
+    QBO sends webhook events when invoices are paid. This handler looks
+    for ``Payment`` events, finds the associated invoice(s), and syncs
+    payment status for any matching purchase orders.
+
+    Args:
+        payload: The parsed JSON webhook payload from QBO.
+    """
+    event_notifications = payload.get("eventNotifications", [])
+    if not isinstance(event_notifications, list):
+        logger.warning("QBO webhook payload has unexpected eventNotifications type")
+        return
+
+    for notification in event_notifications:
+        if not isinstance(notification, dict):
+            continue
+        _process_webhook_notification(notification)
+
+
+def _process_webhook_notification(notification: dict[str, object]) -> None:
+    """Process a single QBO webhook notification.
+
+    Args:
+        notification: A single event notification dict from the QBO webhook payload.
+    """
+    data_change_event = notification.get("dataChangeEvent")
+    if not isinstance(data_change_event, dict):
+        return
+    entities = data_change_event.get("entities")
+    if not isinstance(entities, list):
+        return
+
+    realm_id = notification.get("realmId", "")
+    if not realm_id:
+        return
+
+    for entity in entities:
+        if not isinstance(entity, dict):
+            continue
+        entity_name = entity.get("name", "")
+        operation = entity.get("operation", "")
+
+        if entity_name == "Payment" and operation in ("Create", "Update"):
+            _sync_pos_for_realm(str(realm_id))
+
+
+def _sync_pos_for_realm(realm_id: str) -> None:
+    """Sync QBO invoice status for all outstanding POs in a given realm.
+
+    Args:
+        realm_id: The QBO realm/company ID.
+    """
+    from django_program.registration.purchase_order import PurchaseOrder as POModel  # noqa: PLC0415
+
+    pos_with_qbo = POModel.objects.filter(
+        conference__qbo_realm_id=realm_id,
+        qbo_invoice_id__gt="",
+    ).exclude(
+        status__in=[POModel.Status.PAID, POModel.Status.CANCELLED],
+    )
+
+    for po in pos_with_qbo:
+        try:
+            sync_qbo_invoice_status(po)
+        except Exception:
+            logger.exception("Failed to sync QBO invoice status for PO %s", po.reference)
diff --git a/src/django_program/registration/services/stripe_invoicing.py b/src/django_program/registration/services/stripe_invoicing.py
new file mode 100644
index 0000000..d85bcb2
--- /dev/null
+++ b/src/django_program/registration/services/stripe_invoicing.py
@@ -0,0 +1,314 @@
+"""Stripe Invoicing integration for purchase orders.
+
+Creates, sends, and syncs Stripe Invoices for corporate POs. Uses the
+per-conference ``StripeClient`` pattern so each conference's Stripe account
+handles its own invoices. Supports card and ACH payments via Stripe's
+hosted invoice page.
+"""
+
+import datetime
+import logging
+from decimal import Decimal
+from typing import TYPE_CHECKING
+
+from django_program.registration.purchase_order import (
+    PurchaseOrder,
+    PurchaseOrderLineItem,
+)
+from django_program.registration.services.purchase_orders import (
+    record_payment,
+    update_po_status,
+)
+from django_program.registration.stripe_client import StripeClient
+from django_program.registration.stripe_utils import (
+    convert_amount_for_api,
+    convert_amount_for_db,
+)
+from django_program.settings import get_config
+
+if TYPE_CHECKING:
+    import stripe
+
+    from django_program.conference.models import Conference
+
+logger = logging.getLogger(__name__)
+
+
+def _get_stripe_client(conference: Conference) -> stripe.StripeClient:
+    """Build a raw ``stripe.StripeClient`` for the conference.
+
+    Uses the same validation as :class:`StripeClient` but returns the
+    underlying SDK client for direct API access to invoicing endpoints.
+
+    Args:
+        conference: The conference whose Stripe keys will be used.
+
+    Returns:
+        A configured ``stripe.StripeClient`` instance.
+
+    Raises:
+        ValueError: If the conference has no Stripe secret key configured.
+    """
+    sc = StripeClient(conference)
+    return sc.client
+
+
+def _get_or_create_invoice_customer(
+    client: stripe.StripeClient,
+    *,
+    email: str,
+    name: str,
+    conference_slug: str,
+) -> str:
+    """Find an existing Stripe Customer by email or create one.
+
+    Searches the conference's Stripe account for a customer matching the
+    given email. If none exists, creates a new one with the organization
+    name as metadata.
+
+    Args:
+        client: The Stripe SDK client.
+        email: Customer email address.
+        name: Organization or contact name.
+        conference_slug: Conference slug for metadata tagging.
+
+    Returns:
+        The Stripe Customer ID.
+    """
+    existing = client.v1.customers.list(params={"email": email, "limit": 1})
+    if existing.data:
+        return existing.data[0].id
+
+    customer = client.v1.customers.create(
+        params={
+            "email": email,
+            "name": name,
+            "metadata": {
+                "conference_slug": conference_slug,
+                "source": "purchase_order",
+            },
+        },
+    )
+    return customer.id
+
+
+def create_stripe_invoice(purchase_order: PurchaseOrder) -> str:
+    """Create and send a Stripe Invoice for a purchase order.
+
+    Builds a Stripe Invoice with line items matching the PO, finalizes it,
+    and stores the invoice ID and hosted URL on the PO record.
+
+    Args:
+        purchase_order: The purchase order to invoice.
+
+    Returns:
+        The Stripe-hosted invoice URL where the customer can pay.
+
+    Raises:
+        ValueError: If the conference has no Stripe key, or if the PO
+            already has a Stripe invoice attached.
+        stripe.StripeError: On any Stripe API failure.
+    """
+    if purchase_order.stripe_invoice_id:
+        msg = f"PO {purchase_order.reference} already has a Stripe invoice: {purchase_order.stripe_invoice_id}"
+        raise ValueError(msg)
+
+    conference = purchase_order.conference
+    client = _get_stripe_client(conference)
+    config = get_config()
+    currency = config.currency.lower()
+
+    customer_id = _get_or_create_invoice_customer(
+        client,
+        email=str(purchase_order.contact_email),
+        name=str(purchase_order.organization_name),
+        conference_slug=str(conference.slug),
+    )
+
+    invoice = client.v1.invoices.create(
+        params={
+            "customer": customer_id,
+            "collection_method": "send_invoice",
+            "days_until_due": 30,
+            "currency": currency,
+            "metadata": {
+                "purchase_order_id": str(purchase_order.pk),
+                "purchase_order_ref": str(purchase_order.reference),
+                "conference_slug": str(conference.slug),
+            },
+        },
+    )
+
+    line_items = PurchaseOrderLineItem.objects.filter(purchase_order=purchase_order)
+    for item in line_items:
+        unit_amount = convert_amount_for_api(item.unit_price, currency)
+        client.v1.invoice_items.create(
+            params={
+                "customer": customer_id,
+                "invoice": invoice.id,
+                "description": str(item.description),
+                "quantity": item.quantity,
+                "unit_amount": unit_amount,
+                "currency": currency,
+            },
+        )
+
+    finalized = client.v1.invoices.finalize_invoice(invoice.id)
+
+    client.v1.invoices.send_invoice(finalized.id)
+
+    hosted_url = finalized.hosted_invoice_url or ""
+
+    purchase_order.stripe_invoice_id = finalized.id
+    purchase_order.stripe_invoice_url = hosted_url
+    purchase_order.save(
+        update_fields=[
+            "stripe_invoice_id",
+            "stripe_invoice_url",
+            "updated_at",
+        ]
+    )
+
+    logger.info(
+        "Created Stripe invoice %s for PO %s (customer %s)",
+        finalized.id,
+        purchase_order.reference,
+        customer_id,
+    )
+    return hosted_url
+
+
+def sync_stripe_invoice_status(purchase_order: PurchaseOrder) -> None:
+    """Fetch the Stripe invoice and sync payment status to the PO.
+
+    If Stripe reports the invoice as fully paid, records a payment via
+    :func:`record_payment` with method ``stripe``. Handles partial payments
+    when ``amount_paid < amount_due``.
+
+    Args:
+        purchase_order: The PO with a ``stripe_invoice_id`` to sync.
+
+    Raises:
+        ValueError: If the PO has no Stripe invoice ID.
+        stripe.StripeError: On any Stripe API failure.
+    """
+    if not purchase_order.stripe_invoice_id:
+        msg = f"PO {purchase_order.reference} has no Stripe invoice to sync"
+        raise ValueError(msg)
+
+    conference = purchase_order.conference
+    client = _get_stripe_client(conference)
+    config = get_config()
+    currency = config.currency
+
+    invoice = client.v1.invoices.retrieve(purchase_order.stripe_invoice_id)
+
+    amount_paid = convert_amount_for_db(invoice.amount_paid or 0, currency)
+    already_recorded = purchase_order.total_paid
+
+    new_amount = amount_paid - already_recorded
+    if new_amount <= Decimal("0.00"):
+        logger.debug(
+            "No new payment to record for PO %s (Stripe paid=%s, recorded=%s)",
+            purchase_order.reference,
+            amount_paid,
+            already_recorded,
+        )
+        return
+
+    today = datetime.date.today()  # noqa: DTZ011
+    record_payment(
+        purchase_order,
+        amount=new_amount,
+        method="stripe",
+        reference=purchase_order.stripe_invoice_id,
+        payment_date=today,
+        note=f"Auto-synced from Stripe invoice {purchase_order.stripe_invoice_id}",
+    )
+
+    logger.info(
+        "Synced Stripe payment of %s for PO %s (invoice status: %s)",
+        new_amount,
+        purchase_order.reference,
+        invoice.status,
+    )
+
+
+def handle_invoice_paid_webhook(stripe_event_payload: dict[str, object]) -> None:
+    """Process an ``invoice.paid`` webhook event from Stripe.
+
+    Looks up the PO by the Stripe invoice ID embedded in the event data.
+    If found, records the payment amount and updates the PO status.
+
+    Args:
+        stripe_event_payload: The full Stripe event payload dict. Expected
+            to contain ``data.object`` with invoice fields.
+    """
+    data_wrapper: object = stripe_event_payload.get("data", {})
+    if not isinstance(data_wrapper, dict):
+        logger.warning("Unexpected webhook payload structure")
+        return
+
+    invoice_data: object = data_wrapper["object"] if "object" in data_wrapper else {}  # noqa: SIM401
+    if not isinstance(invoice_data, dict):
+        logger.warning("Unexpected invoice data type in webhook payload")
+        return
+
+    stripe_invoice_id = str(invoice_data["id"]) if "id" in invoice_data else ""
+    if not stripe_invoice_id:
+        logger.warning("No invoice ID in webhook payload")
+        return
+
+    try:
+        po = PurchaseOrder.objects.select_for_update().get(
+            stripe_invoice_id=stripe_invoice_id,
+        )
+    except PurchaseOrder.DoesNotExist:
+        logger.debug(
+            "No PO found for Stripe invoice %s (may not be a PO invoice)",
+            stripe_invoice_id,
+        )
+        return
+
+    if po.status in (PurchaseOrder.Status.PAID, PurchaseOrder.Status.CANCELLED):
+        logger.info(
+            "PO %s already %s, skipping webhook for invoice %s",
+            po.reference,
+            po.status,
+            stripe_invoice_id,
+        )
+        return
+
+    config = get_config()
+    currency = config.currency
+    amount_paid_cents = invoice_data["amount_paid"] if "amount_paid" in invoice_data else 0  # noqa: SIM401
+    amount_paid = convert_amount_for_db(int(amount_paid_cents), currency)
+
+    already_recorded = po.total_paid
+    new_amount = amount_paid - already_recorded
+
+    if new_amount <= Decimal("0.00"):
+        logger.debug(
+            "Webhook for invoice %s: no new amount to record (paid=%s, recorded=%s)",
+            stripe_invoice_id,
+            amount_paid,
+            already_recorded,
+        )
+        update_po_status(po)
+        return
+
+    today = datetime.date.today()  # noqa: DTZ011
+    record_payment(
+        po,
+        amount=new_amount,
+        method="stripe",
+        reference=stripe_invoice_id,
+        payment_date=today,
+        note=f"Stripe webhook invoice.paid ({stripe_invoice_id})",
+    )
+
+    logger.info(
+        "Processed invoice.paid webhook: recorded %s for PO %s",
+        new_amount,
+        po.reference,
+    )
diff --git a/uv.lock b/uv.lock
index 19d08cb..cd863c2 100644
--- a/uv.lock
+++ b/uv.lock
@@ -271,6 +271,7 @@ source = { editable = "." }
 dependencies = [
     { name = "django" },
     { name = "django-fernet-encrypted-fields" },
+    { name = "httpx" },
     { name = "pillow" },
     { name = "pretalx-client" },
     { name = "qrcode", extra = ["pil"] },
@@ -329,6 +330,7 @@ test = [
 requires-dist = [
     { name = "django", specifier = ">=5.2" },
     { name = "django-fernet-encrypted-fields", specifier = ">=0.3.1" },
+    { name = "httpx", specifier = ">=0.28.1" },
     { name = "pillow", specifier = ">=12.1.1" },
     { name = "pretalx-client", editable = "packages/pretalx-client" },
     { name = "qrcode", extras = ["pil"], specifier = ">=8.2" },

From 89aac394f442624c3901512c98bd640378f75b4a Mon Sep 17 00:00:00 2001
From: Jacob Coffee <jacob@z7x.org>
Date: Thu, 19 Mar 2026 13:48:58 -0500
Subject: [PATCH 6/7] fix: seed demo Stripe/QBO keys so PO integration buttons
 render in UI

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 examples/seed.py | 24 +++++++++++++++++-------
 1 file changed, 17 insertions(+), 7 deletions(-)

diff --git a/examples/seed.py b/examples/seed.py
index e20a281..3401afb 100644
--- a/examples/seed.py
+++ b/examples/seed.py
@@ -298,14 +298,24 @@ def _create_conference(self) -> Conference:
         # Use whatever conference bootstrap_conference created
         conference = Conference.objects.first()
         if conference:
-            # Ensure budget fields are populated
+            # Ensure budget and integration fields are populated for demo
+            changed = False
             if not conference.revenue_budget:
-                Conference.objects.filter(pk=conference.pk).update(
-                    revenue_budget=Decimal("50000.00"),
-                    target_attendance=150,
-                    grant_budget=Decimal("15000.00"),
-                )
-                conference.refresh_from_db()
+                conference.revenue_budget = Decimal("50000.00")
+                conference.target_attendance = 150
+                conference.grant_budget = Decimal("15000.00")
+                changed = True
+            if not conference.stripe_secret_key:
+                conference.stripe_secret_key = "sk_test_demo_not_real"
+                conference.stripe_publishable_key = "pk_test_demo_not_real"
+                changed = True
+            if not conference.qbo_realm_id:
+                conference.qbo_realm_id = "1234567890"
+                conference.qbo_client_id = "demo-client-id"
+                conference.qbo_client_secret = "demo-client-secret"
+                changed = True
+            if changed:
+                conference.save()
             return conference
         # Fallback: create one if bootstrap wasn't run
         conference, _ = Conference.objects.get_or_create(

From 0ef521d75d6236767f1ab8b854d6ac22de63d861 Mon Sep 17 00:00:00 2001
From: Jacob Coffee <jacob@z7x.org>
Date: Thu, 19 Mar 2026 14:16:26 -0500
Subject: [PATCH 7/7] fix: address all PR #59 review comments

- Validate amount > 0 and method in record_payment/issue_credit_note
- Use conference currency_symbol in invoice PDF instead of hardcoded $
- Wrap handle_invoice_paid_webhook in transaction.atomic()
- Cap QBO webhook sync to 50 POs to prevent timeouts
- Fix PO balance_outstanding to subtract credits and exclude cancelled POs
- Add today to detail view context for payment date default
- Fix double-minus display bug in list template for negative balances
- Annotate total_paid/total_credited in list view and admin to avoid N+1
- PurchaseOrder properties use annotations when available
- Add sidebar accessibility (role=button, tabindex, aria-expanded, keydown)
- Add 81 new tests: view tests, Stripe invoicing tests, QBO invoicing tests

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 .../templates/django_program/manage/base.html |  29 +-
 .../manage/purchase_order_list.html           |   2 +-
 src/django_program/manage/views_financial.py  |  31 +-
 .../manage/views_purchase_orders.py           |  18 +-
 src/django_program/registration/admin.py      |  15 +
 .../registration/purchase_order.py            |  18 +-
 .../registration/services/purchase_orders.py  |  58 +-
 .../registration/services/qbo_invoicing.py    |  20 +-
 .../registration/services/stripe_invoicing.py |  99 +--
 .../test_manage/test_purchase_order_views.py  | 573 ++++++++++++++++++
 tests/test_registration/test_qbo_invoicing.py | 514 ++++++++++++++++
 .../test_stripe_invoicing.py                  | 400 ++++++++++++
 12 files changed, 1687 insertions(+), 90 deletions(-)
 create mode 100644 tests/test_manage/test_purchase_order_views.py
 create mode 100644 tests/test_registration/test_qbo_invoicing.py
 create mode 100644 tests/test_registration/test_stripe_invoicing.py

diff --git a/src/django_program/manage/templates/django_program/manage/base.html b/src/django_program/manage/templates/django_program/manage/base.html
index b0089e4..a5dcccd 100644
--- a/src/django_program/manage/templates/django_program/manage/base.html
+++ b/src/django_program/manage/templates/django_program/manage/base.html
@@ -1067,7 +1067,7 @@
     <nav class="sidebar" aria-label="Conference navigation">
       {# ── Conference ── #}
       <div class="sidebar-section" data-section="conference">
-        <div class="sidebar-section-title">{{ conference.name }} <svg class="sidebar-collapse-icon" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round"><path d="M4 6l4 4 4-4"/></svg></div>
+        <div class="sidebar-section-title" role="button" tabindex="0" aria-expanded="true">{{ conference.name }} <svg class="sidebar-collapse-icon" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round"><path d="M4 6l4 4 4-4"/></svg></div>
         <ul class="sidebar-nav">
           <li>
             <a href="{% url 'manage:dashboard' conference.slug %}" class="{% if active_nav == 'dashboard' %}active{% endif %}">
@@ -1084,7 +1084,7 @@
 
       {# ── Program ── #}
       <div class="sidebar-section" data-section="program">
-        <div class="sidebar-section-title">Program <svg class="sidebar-collapse-icon" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round"><path d="M4 6l4 4 4-4"/></svg></div>
+        <div class="sidebar-section-title" role="button" tabindex="0" aria-expanded="true">Program <svg class="sidebar-collapse-icon" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round"><path d="M4 6l4 4 4-4"/></svg></div>
         <ul class="sidebar-nav">
           <li>
             <a href="{% url 'manage:section-list' conference.slug %}" class="{% if active_nav == 'sections' %}active{% endif %}">
@@ -1147,7 +1147,7 @@
 
       {# ── Registration ── #}
       <div class="sidebar-section" data-section="registration">
-        <div class="sidebar-section-title">Registration <svg class="sidebar-collapse-icon" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round"><path d="M4 6l4 4 4-4"/></svg></div>
+        <div class="sidebar-section-title" role="button" tabindex="0" aria-expanded="true">Registration <svg class="sidebar-collapse-icon" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round"><path d="M4 6l4 4 4-4"/></svg></div>
         <ul class="sidebar-nav">
           <li class="sidebar-sublabel" data-subsection="reg-people">People <svg class="sidebar-collapse-icon" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round"><path d="M4 6l4 4 4-4"/></svg></li>
         </ul>
@@ -1211,7 +1211,7 @@
 
       {# ── Sponsors ── #}
       <div class="sidebar-section" data-section="sponsors">
-        <div class="sidebar-section-title">Sponsors <svg class="sidebar-collapse-icon" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round"><path d="M4 6l4 4 4-4"/></svg></div>
+        <div class="sidebar-section-title" role="button" tabindex="0" aria-expanded="true">Sponsors <svg class="sidebar-collapse-icon" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round"><path d="M4 6l4 4 4-4"/></svg></div>
         <ul class="sidebar-nav">
           <li>
             <a href="{% url 'manage:sponsor-level-list' conference.slug %}" class="{% if active_nav == 'sponsor-levels' %}active{% endif %}">
@@ -1228,7 +1228,7 @@
 
       {# ── On-site ── #}
       <div class="sidebar-section" data-section="onsite">
-        <div class="sidebar-section-title">On-site <svg class="sidebar-collapse-icon" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round"><path d="M4 6l4 4 4-4"/></svg></div>
+        <div class="sidebar-section-title" role="button" tabindex="0" aria-expanded="true">On-site <svg class="sidebar-collapse-icon" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round"><path d="M4 6l4 4 4-4"/></svg></div>
         <ul class="sidebar-nav">
           <li>
             <a href="{% url 'manage:checkin-dashboard' conference.slug %}" class="{% if active_nav == 'checkin' %}active{% endif %}">
@@ -1245,7 +1245,7 @@
 
       {# ── Finance & Insights ── #}
       <div class="sidebar-section" data-section="finance">
-        <div class="sidebar-section-title">Finance & Insights <svg class="sidebar-collapse-icon" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round"><path d="M4 6l4 4 4-4"/></svg></div>
+        <div class="sidebar-section-title" role="button" tabindex="0" aria-expanded="true">Finance & Insights <svg class="sidebar-collapse-icon" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round"><path d="M4 6l4 4 4-4"/></svg></div>
         <ul class="sidebar-nav">
           <li>
             <a href="{% url 'manage:financial-dashboard' conference.slug %}" class="{% if active_nav == 'financial' %}active{% endif %}">
@@ -1278,7 +1278,7 @@
       {# ── Sync & Overrides (utility) ── #}
       <hr class="sidebar-utility-separator">
       <div class="sidebar-section" data-section="sync-overrides">
-        <div class="sidebar-section-title">Sync & Overrides <svg class="sidebar-collapse-icon" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round"><path d="M4 6l4 4 4-4"/></svg></div>
+        <div class="sidebar-section-title" role="button" tabindex="0" aria-expanded="true">Sync & Overrides <svg class="sidebar-collapse-icon" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round"><path d="M4 6l4 4 4-4"/></svg></div>
         <ul class="sidebar-nav">
           <li>
             <div class="sidebar-nav-expandable">
@@ -1341,12 +1341,23 @@
       var hasActive = section.querySelector('.sidebar-nav li a.active, .sidebar-subnav li a.active');
       if (stored[id] && !hasActive) {
         section.classList.add('collapsed');
+        title.setAttribute('aria-expanded', 'false');
       }
 
-      title.addEventListener('click', function() {
+      function toggleSection() {
         section.classList.toggle('collapsed');
-        stored[id] = section.classList.contains('collapsed');
+        var isCollapsed = section.classList.contains('collapsed');
+        stored[id] = isCollapsed;
+        title.setAttribute('aria-expanded', String(!isCollapsed));
         try { localStorage.setItem(KEY, JSON.stringify(stored)); } catch(e) {}
+      }
+
+      title.addEventListener('click', toggleSection);
+      title.addEventListener('keydown', function(e) {
+        if (e.key === 'Enter' || e.key === ' ') {
+          e.preventDefault();
+          toggleSection();
+        }
       });
     });
 
diff --git a/src/django_program/manage/templates/django_program/manage/purchase_order_list.html b/src/django_program/manage/templates/django_program/manage/purchase_order_list.html
index fc431ab..53867d4 100644
--- a/src/django_program/manage/templates/django_program/manage/purchase_order_list.html
+++ b/src/django_program/manage/templates/django_program/manage/purchase_order_list.html
@@ -66,7 +66,7 @@ <h1>Purchase Orders</h1>
         {% if po.balance_due > 0 %}
         <span style="color: var(--color-warning); font-weight: 600;">${{ po.balance_due }}</span>
         {% elif po.balance_due < 0 %}
-        <span style="color: var(--color-accent); font-weight: 600;">-${{ po.balance_due|floatformat:2 }}</span>
+        <span style="color: var(--color-accent); font-weight: 600;">-${{ po.balance_due|floatformat:2|cut:"-" }}</span>
         {% else %}
         <span style="color: var(--color-success);">$0.00</span>
         {% endif %}
diff --git a/src/django_program/manage/views_financial.py b/src/django_program/manage/views_financial.py
index 29747ee..edb1562 100644
--- a/src/django_program/manage/views_financial.py
+++ b/src/django_program/manage/views_financial.py
@@ -38,7 +38,11 @@
     Payment,
     TicketType,
 )
-from django_program.registration.purchase_order import PurchaseOrder, PurchaseOrderPayment
+from django_program.registration.purchase_order import (
+    PurchaseOrder,
+    PurchaseOrderCreditNote,
+    PurchaseOrderPayment,
+)
 
 _ZERO = Decimal("0.00")
 
@@ -499,27 +503,40 @@ def get_context_data(self, **kwargs: object) -> dict[str, object]:  # noqa: PLR0
         total_pos = sum(d["count"] for d in po_by_status.values())  # type: ignore[arg-type]
 
         po_revenue = (
-            po_qs.filter(
+            po_qs.exclude(status=PurchaseOrder.Status.CANCELLED)
+            .filter(
                 status__in=[
                     PurchaseOrder.Status.PAID,
                     PurchaseOrder.Status.OVERPAID,
                     PurchaseOrder.Status.PARTIALLY_PAID,
                 ]
-            ).aggregate(total=Sum("total"))["total"]
+            )
+            .aggregate(total=Sum("total"))["total"]
             or _ZERO
         )
         po_collected = (
-            PurchaseOrderPayment.objects.filter(purchase_order__conference=conference).aggregate(total=Sum("amount"))[
-                "total"
-            ]
+            PurchaseOrderPayment.objects.filter(
+                purchase_order__conference=conference,
+            )
+            .exclude(purchase_order__status=PurchaseOrder.Status.CANCELLED)
+            .aggregate(total=Sum("amount"))["total"]
+            or _ZERO
+        )
+        po_credited = (
+            PurchaseOrderCreditNote.objects.filter(
+                purchase_order__conference=conference,
+            )
+            .exclude(purchase_order__status=PurchaseOrder.Status.CANCELLED)
+            .aggregate(total=Sum("amount"))["total"]
             or _ZERO
         )
-        po_balance = po_revenue - po_collected
+        po_balance = po_revenue - po_collected - po_credited
 
         context["po_by_status"] = po_by_status
         context["total_pos"] = total_pos
         context["po_revenue"] = po_revenue
         context["po_collected"] = po_collected
+        context["po_credited"] = po_credited
         context["po_balance_outstanding"] = po_balance
 
         po_payment_rows = (
diff --git a/src/django_program/manage/views_purchase_orders.py b/src/django_program/manage/views_purchase_orders.py
index 378053b..33f430f 100644
--- a/src/django_program/manage/views_purchase_orders.py
+++ b/src/django_program/manage/views_purchase_orders.py
@@ -6,6 +6,8 @@
 from typing import TYPE_CHECKING
 
 from django.contrib import messages
+from django.db.models import Sum, Value
+from django.db.models.functions import Coalesce
 from django.http import HttpResponse
 from django.shortcuts import get_object_or_404, redirect
 from django.template.response import TemplateResponse
@@ -101,8 +103,19 @@ def get_context_data(self, **kwargs: object) -> dict[str, object]:
         return context
 
     def get_queryset(self) -> QuerySet[PurchaseOrder]:
-        """Return purchase orders for the current conference, optionally filtered by status."""
-        qs = PurchaseOrder.objects.filter(conference=self.conference).order_by("-created_at")
+        """Return purchase orders for the current conference, optionally filtered by status.
+
+        Annotates ``_annotated_total_paid`` and ``_annotated_total_credited`` so
+        that ``balance_due`` can be computed without per-row aggregate queries.
+        """
+        qs = (
+            PurchaseOrder.objects.filter(conference=self.conference)
+            .annotate(
+                _annotated_total_paid=Coalesce(Sum("payments__amount"), Value(Decimal("0.00"))),
+                _annotated_total_credited=Coalesce(Sum("credit_notes__amount"), Value(Decimal("0.00"))),
+            )
+            .order_by("-created_at")
+        )
         status = self.request.GET.get("status", "")
         if status and status in dict(PurchaseOrder.Status.choices):
             qs = qs.filter(status=status)
@@ -124,6 +137,7 @@ def get_context_data(self, **kwargs: object) -> dict[str, object]:
         context["payments"] = PurchaseOrderPayment.objects.filter(purchase_order=po).select_related("entered_by")
         context["credit_notes"] = PurchaseOrderCreditNote.objects.filter(purchase_order=po).select_related("issued_by")
         context["payment_methods"] = PurchaseOrderPayment.Method.choices
+        context["today"] = timezone.now().date().isoformat()
         return context
 
     def get_queryset(self) -> QuerySet[PurchaseOrder]:
diff --git a/src/django_program/registration/admin.py b/src/django_program/registration/admin.py
index 4f4c01d..a6e00a6 100644
--- a/src/django_program/registration/admin.py
+++ b/src/django_program/registration/admin.py
@@ -1,6 +1,10 @@
 """Django admin configuration for the registration app."""
 
+from decimal import Decimal
+
 from django.contrib import admin
+from django.db.models import QuerySet, Sum, Value
+from django.db.models.functions import Coalesce
 from django.http import HttpRequest  # noqa: TC002
 
 from django_program.registration.badge import Badge, BadgeTemplate
@@ -565,6 +569,17 @@ class PurchaseOrderAdmin(admin.ModelAdmin):
     readonly_fields = ("reference", "subtotal", "total", "balance_due_display", "total_paid_display")
     inlines = (PurchaseOrderLineItemInline, PurchaseOrderPaymentInline, PurchaseOrderCreditNoteInline)
 
+    def get_queryset(self, request: HttpRequest) -> QuerySet[PurchaseOrder]:
+        """Annotate payment and credit totals to avoid N+1 aggregate queries."""
+        return (
+            super()
+            .get_queryset(request)
+            .annotate(
+                _annotated_total_paid=Coalesce(Sum("payments__amount"), Value(Decimal("0.00"))),
+                _annotated_total_credited=Coalesce(Sum("credit_notes__amount"), Value(Decimal("0.00"))),
+            )
+        )
+
     @admin.display(description="Balance Due")
     def balance_due_display(self, obj: PurchaseOrder) -> str:
         """Render the computed balance due for the list and detail views."""
diff --git a/src/django_program/registration/purchase_order.py b/src/django_program/registration/purchase_order.py
index dc05aef..5f9086e 100644
--- a/src/django_program/registration/purchase_order.py
+++ b/src/django_program/registration/purchase_order.py
@@ -94,12 +94,26 @@ def __str__(self) -> str:
 
     @property
     def total_paid(self) -> Decimal:
-        """Return the sum of all recorded payment amounts."""
+        """Return the sum of all recorded payment amounts.
+
+        Uses the ``_annotated_total_paid`` annotation when available (set by
+        list views) to avoid per-row aggregate queries.
+        """
+        annotated = getattr(self, "_annotated_total_paid", None)
+        if annotated is not None:
+            return Decimal(str(annotated))
         return self.payments.aggregate(total=models.Sum("amount"))["total"] or Decimal("0.00")
 
     @property
     def total_credited(self) -> Decimal:
-        """Return the sum of all credit note amounts."""
+        """Return the sum of all credit note amounts.
+
+        Uses the ``_annotated_total_credited`` annotation when available (set by
+        list views) to avoid per-row aggregate queries.
+        """
+        annotated = getattr(self, "_annotated_total_credited", None)
+        if annotated is not None:
+            return Decimal(str(annotated))
         return self.credit_notes.aggregate(total=models.Sum("amount"))["total"] or Decimal("0.00")
 
     @property
diff --git a/src/django_program/registration/services/purchase_orders.py b/src/django_program/registration/services/purchase_orders.py
index 2a54c0d..7f0b8df 100644
--- a/src/django_program/registration/services/purchase_orders.py
+++ b/src/django_program/registration/services/purchase_orders.py
@@ -162,8 +162,18 @@ def record_payment(  # noqa: PLR0913
         The newly created PurchaseOrderPayment.
 
     Raises:
-        ValueError: If the PO is cancelled.
+        ValueError: If the amount is not positive, the method is invalid,
+            or the PO is cancelled.
     """
+    if amount <= Decimal("0.00"):
+        msg = f"Payment amount must be positive, got {amount}"
+        raise ValueError(msg)
+
+    valid_methods = {choice.value for choice in PurchaseOrderPayment.Method}
+    if method not in valid_methods:
+        msg = f"Invalid payment method '{method}', must be one of {sorted(valid_methods)}"
+        raise ValueError(msg)
+
     # Lock the PO row to prevent concurrent status races.
     po = PurchaseOrder.objects.select_for_update().get(pk=purchase_order.pk)
     if po.status == PurchaseOrder.Status.CANCELLED:
@@ -211,8 +221,12 @@ def issue_credit_note(
         The newly created PurchaseOrderCreditNote.
 
     Raises:
-        ValueError: If the PO is cancelled.
+        ValueError: If the amount is not positive or the PO is cancelled.
     """
+    if amount <= Decimal("0.00"):
+        msg = f"Credit note amount must be positive, got {amount}"
+        raise ValueError(msg)
+
     # Lock the PO row to prevent concurrent status races.
     po = PurchaseOrder.objects.select_for_update().get(pk=purchase_order.pk)
     if po.status == PurchaseOrder.Status.CANCELLED:
@@ -327,6 +341,8 @@ def generate_invoice_pdf(purchase_order: PurchaseOrder) -> bytes:
     from reportlab.lib.units import mm  # noqa: PLC0415
     from reportlab.pdfgen import canvas  # noqa: PLC0415
 
+    from django_program.settings import get_config  # noqa: PLC0415
+
     buf = io.BytesIO()
     width, height = A4
     c = canvas.Canvas(buf, pagesize=A4)
@@ -334,13 +350,14 @@ def generate_invoice_pdf(purchase_order: PurchaseOrder) -> bytes:
     usable_width = width - 2 * margin
 
     conference = purchase_order.conference
+    currency_sym = get_config().currency_symbol or "$"
 
     y = _draw_invoice_letterhead(c, conference, margin, height - margin, width)
     y = _draw_invoice_title(c, purchase_order, margin, y)
     y = _draw_bill_to(c, purchase_order, margin, y)
-    y = _draw_line_items_table(c, purchase_order, margin, y, usable_width)
-    y = _draw_financial_summary(c, purchase_order, margin, y, usable_width)
-    y = _draw_payment_history(c, purchase_order, margin, y, usable_width)
+    y = _draw_line_items_table(c, purchase_order, margin, y, usable_width, currency_sym)
+    y = _draw_financial_summary(c, purchase_order, margin, y, usable_width, currency_sym)
+    y = _draw_payment_history(c, purchase_order, margin, y, usable_width, currency_sym)
     _draw_invoice_footer(c, conference, margin, y, width)
 
     c.showPage()
@@ -455,8 +472,8 @@ def _draw_bill_to(c: object, purchase_order: PurchaseOrder, margin: float, y: fl
     return y
 
 
-def _draw_line_items_table(
-    c: object, purchase_order: PurchaseOrder, margin: float, y: float, usable_width: float
+def _draw_line_items_table(  # noqa: PLR0913
+    c: object, purchase_order: PurchaseOrder, margin: float, y: float, usable_width: float, currency_sym: str = "$"
 ) -> float:
     """Draw the line items table with headers and rows.
 
@@ -466,6 +483,7 @@ def _draw_line_items_table(
         margin: Left margin in points.
         y: Current y position.
         usable_width: Available text width in points.
+        currency_sym: Currency symbol to display before monetary values.
 
     Returns:
         Updated y position after the table.
@@ -497,8 +515,8 @@ def _draw_line_items_table(
             c.drawString(col_desc_x, y, segment)  # type: ignore[attr-defined]
             if i == 0:
                 c.drawRightString(col_qty_x + 30, y, str(item.quantity))  # type: ignore[attr-defined]
-                c.drawRightString(col_price_x + 40, y, f"${item.unit_price}")  # type: ignore[attr-defined]
-                c.drawRightString(col_total_x + 40, y, f"${item.line_total}")  # type: ignore[attr-defined]
+                c.drawRightString(col_price_x + 40, y, f"{currency_sym}{item.unit_price}")  # type: ignore[attr-defined]
+                c.drawRightString(col_total_x + 40, y, f"{currency_sym}{item.line_total}")  # type: ignore[attr-defined]
             y -= 5 * mm
 
     y -= 3 * mm
@@ -509,8 +527,8 @@ def _draw_line_items_table(
     return y
 
 
-def _draw_financial_summary(
-    c: object, purchase_order: PurchaseOrder, margin: float, y: float, usable_width: float
+def _draw_financial_summary(  # noqa: PLR0913
+    c: object, purchase_order: PurchaseOrder, margin: float, y: float, usable_width: float, currency_sym: str = "$"
 ) -> float:
     """Draw the financial summary (subtotal, total, paid, credits, balance).
 
@@ -520,6 +538,7 @@ def _draw_financial_summary(
         margin: Left margin in points.
         y: Current y position.
         usable_width: Available text width in points.
+        currency_sym: Currency symbol to display before monetary values.
 
     Returns:
         Updated y position after the summary.
@@ -529,16 +548,16 @@ def _draw_financial_summary(
     value_x = margin + usable_width * 0.85 + 40
 
     summary_lines: list[tuple[str, str, str, bool]] = [
-        ("Subtotal:", f"${purchase_order.subtotal}", "Helvetica", False),
-        ("Total:", f"${purchase_order.total}", "Helvetica-Bold", False),
-        ("Total Paid:", f"${purchase_order.total_paid}", "Helvetica", False),
+        ("Subtotal:", f"{currency_sym}{purchase_order.subtotal}", "Helvetica", False),
+        ("Total:", f"{currency_sym}{purchase_order.total}", "Helvetica-Bold", False),
+        ("Total Paid:", f"{currency_sym}{purchase_order.total_paid}", "Helvetica", False),
     ]
 
     total_credited = purchase_order.total_credited
     if total_credited:
-        summary_lines.append(("Total Credits:", f"${total_credited}", "Helvetica", False))
+        summary_lines.append(("Total Credits:", f"{currency_sym}{total_credited}", "Helvetica", False))
 
-    summary_lines.append(("Balance Due:", f"${purchase_order.balance_due}", "Helvetica-Bold", True))
+    summary_lines.append(("Balance Due:", f"{currency_sym}{purchase_order.balance_due}", "Helvetica-Bold", True))
 
     for label, value, font, is_large in summary_lines:
         size = 12 if is_large else 10
@@ -551,8 +570,8 @@ def _draw_financial_summary(
     return y
 
 
-def _draw_payment_history(
-    c: object, purchase_order: PurchaseOrder, margin: float, y: float, usable_width: float
+def _draw_payment_history(  # noqa: PLR0913
+    c: object, purchase_order: PurchaseOrder, margin: float, y: float, usable_width: float, currency_sym: str = "$"
 ) -> float:
     """Draw the payment history section.
 
@@ -562,6 +581,7 @@ def _draw_payment_history(
         margin: Left margin in points.
         y: Current y position.
         usable_width: Available text width in points.
+        currency_sym: Currency symbol to display before monetary values.
 
     Returns:
         Updated y position after the payment history.
@@ -585,7 +605,7 @@ def _draw_payment_history(
         date_str = payment.payment_date.strftime("%b %d, %Y")
         method_str = payment.get_method_display()
         ref_str = f" (ref: {payment.reference})" if payment.reference else ""
-        line = f"{date_str}  —  {method_str}  —  ${payment.amount}{ref_str}"
+        line = f"{date_str}  —  {method_str}  —  {currency_sym}{payment.amount}{ref_str}"
         c.drawString(margin, y, line)  # type: ignore[attr-defined]
         y -= 5 * mm
 
diff --git a/src/django_program/registration/services/qbo_invoicing.py b/src/django_program/registration/services/qbo_invoicing.py
index 707ceda..0bf97e7 100644
--- a/src/django_program/registration/services/qbo_invoicing.py
+++ b/src/django_program/registration/services/qbo_invoicing.py
@@ -544,8 +544,15 @@ def _process_webhook_notification(notification: dict[str, object]) -> None:
             _sync_pos_for_realm(str(realm_id))
 
 
+_WEBHOOK_SYNC_LIMIT = 50
+
+
 def _sync_pos_for_realm(realm_id: str) -> None:
-    """Sync QBO invoice status for all outstanding POs in a given realm.
+    """Sync QBO invoice status for outstanding POs in a given realm.
+
+    Each PO requires a separate HTTP request to QBO, so this function caps
+    the number of POs synced per webhook invocation to avoid timeouts. If
+    more outstanding POs exist than the limit, a warning is logged.
 
     Args:
         realm_id: The QBO realm/company ID.
@@ -559,7 +566,16 @@ def _sync_pos_for_realm(realm_id: str) -> None:
         status__in=[POModel.Status.PAID, POModel.Status.CANCELLED],
     )
 
-    for po in pos_with_qbo:
+    total_count = pos_with_qbo.count()
+    if total_count > _WEBHOOK_SYNC_LIMIT:
+        logger.warning(
+            "QBO realm %s has %d outstanding POs, syncing only the first %d to avoid timeout",
+            realm_id,
+            total_count,
+            _WEBHOOK_SYNC_LIMIT,
+        )
+
+    for po in pos_with_qbo[:_WEBHOOK_SYNC_LIMIT]:
         try:
             sync_qbo_invoice_status(po)
         except Exception:
diff --git a/src/django_program/registration/services/stripe_invoicing.py b/src/django_program/registration/services/stripe_invoicing.py
index d85bcb2..720e26c 100644
--- a/src/django_program/registration/services/stripe_invoicing.py
+++ b/src/django_program/registration/services/stripe_invoicing.py
@@ -11,6 +11,8 @@
 from decimal import Decimal
 from typing import TYPE_CHECKING
 
+from django.db import transaction
+
 from django_program.registration.purchase_order import (
     PurchaseOrder,
     PurchaseOrderLineItem,
@@ -259,56 +261,57 @@ def handle_invoice_paid_webhook(stripe_event_payload: dict[str, object]) -> None
         logger.warning("No invoice ID in webhook payload")
         return
 
-    try:
-        po = PurchaseOrder.objects.select_for_update().get(
-            stripe_invoice_id=stripe_invoice_id,
-        )
-    except PurchaseOrder.DoesNotExist:
-        logger.debug(
-            "No PO found for Stripe invoice %s (may not be a PO invoice)",
-            stripe_invoice_id,
+    with transaction.atomic():
+        try:
+            po = PurchaseOrder.objects.select_for_update().get(
+                stripe_invoice_id=stripe_invoice_id,
+            )
+        except PurchaseOrder.DoesNotExist:
+            logger.debug(
+                "No PO found for Stripe invoice %s (may not be a PO invoice)",
+                stripe_invoice_id,
+            )
+            return
+
+        if po.status in (PurchaseOrder.Status.PAID, PurchaseOrder.Status.CANCELLED):
+            logger.info(
+                "PO %s already %s, skipping webhook for invoice %s",
+                po.reference,
+                po.status,
+                stripe_invoice_id,
+            )
+            return
+
+        config = get_config()
+        currency = config.currency
+        amount_paid_cents = invoice_data["amount_paid"] if "amount_paid" in invoice_data else 0  # noqa: SIM401
+        amount_paid = convert_amount_for_db(int(amount_paid_cents), currency)
+
+        already_recorded = po.total_paid
+        new_amount = amount_paid - already_recorded
+
+        if new_amount <= Decimal("0.00"):
+            logger.debug(
+                "Webhook for invoice %s: no new amount to record (paid=%s, recorded=%s)",
+                stripe_invoice_id,
+                amount_paid,
+                already_recorded,
+            )
+            update_po_status(po)
+            return
+
+        today = datetime.date.today()  # noqa: DTZ011
+        record_payment(
+            po,
+            amount=new_amount,
+            method="stripe",
+            reference=stripe_invoice_id,
+            payment_date=today,
+            note=f"Stripe webhook invoice.paid ({stripe_invoice_id})",
         )
-        return
 
-    if po.status in (PurchaseOrder.Status.PAID, PurchaseOrder.Status.CANCELLED):
         logger.info(
-            "PO %s already %s, skipping webhook for invoice %s",
+            "Processed invoice.paid webhook: recorded %s for PO %s",
+            new_amount,
             po.reference,
-            po.status,
-            stripe_invoice_id,
-        )
-        return
-
-    config = get_config()
-    currency = config.currency
-    amount_paid_cents = invoice_data["amount_paid"] if "amount_paid" in invoice_data else 0  # noqa: SIM401
-    amount_paid = convert_amount_for_db(int(amount_paid_cents), currency)
-
-    already_recorded = po.total_paid
-    new_amount = amount_paid - already_recorded
-
-    if new_amount <= Decimal("0.00"):
-        logger.debug(
-            "Webhook for invoice %s: no new amount to record (paid=%s, recorded=%s)",
-            stripe_invoice_id,
-            amount_paid,
-            already_recorded,
         )
-        update_po_status(po)
-        return
-
-    today = datetime.date.today()  # noqa: DTZ011
-    record_payment(
-        po,
-        amount=new_amount,
-        method="stripe",
-        reference=stripe_invoice_id,
-        payment_date=today,
-        note=f"Stripe webhook invoice.paid ({stripe_invoice_id})",
-    )
-
-    logger.info(
-        "Processed invoice.paid webhook: recorded %s for PO %s",
-        new_amount,
-        po.reference,
-    )
diff --git a/tests/test_manage/test_purchase_order_views.py b/tests/test_manage/test_purchase_order_views.py
new file mode 100644
index 0000000..53bc61a
--- /dev/null
+++ b/tests/test_manage/test_purchase_order_views.py
@@ -0,0 +1,573 @@
+"""Tests for purchase order management dashboard views."""
+
+from datetime import date
+from decimal import Decimal
+from unittest.mock import patch
+
+import pytest
+from django.contrib.auth.models import User
+from django.test import Client
+from django.urls import reverse
+
+from django_program.conference.models import Conference
+from django_program.registration.models import TicketType
+from django_program.registration.purchase_order import PurchaseOrder
+from django_program.registration.services.purchase_orders import (
+    create_purchase_order,
+    send_purchase_order,
+)
+
+# ---------------------------------------------------------------------------
+# Fixtures
+# ---------------------------------------------------------------------------
+
+
+@pytest.fixture
+def superuser(db) -> User:
+    return User.objects.create_superuser(username="poadmin", password="password", email="poadmin@test.com")
+
+
+@pytest.fixture
+def conference(db) -> Conference:
+    return Conference.objects.create(
+        name="PO Test Conf",
+        slug="po-test-conf",
+        start_date=date(2027, 6, 1),
+        end_date=date(2027, 6, 3),
+        timezone="UTC",
+        is_active=True,
+    )
+
+
+@pytest.fixture
+def ticket_type(conference) -> TicketType:
+    return TicketType.objects.create(
+        conference=conference,
+        name="Corporate",
+        slug="corporate",
+        price=Decimal("250.00"),
+        total_quantity=0,
+        limit_per_user=10,
+        is_active=True,
+    )
+
+
+@pytest.fixture
+def logged_in_client(superuser) -> Client:
+    c = Client()
+    c.force_login(superuser)
+    return c
+
+
+@pytest.fixture
+def purchase_order(conference, superuser, ticket_type) -> PurchaseOrder:
+    return create_purchase_order(
+        conference=conference,
+        organization_name="Acme Corp",
+        contact_email="billing@acme.com",
+        contact_name="Jane Doe",
+        billing_address="123 Corporate Ave",
+        line_items=[
+            {
+                "description": "Corporate Ticket",
+                "quantity": 5,
+                "unit_price": Decimal("250.00"),
+                "ticket_type": ticket_type,
+            },
+        ],
+        notes="Test PO",
+        created_by=superuser,
+    )
+
+
+def _po_url(name: str, conference_slug: str, pk: int | None = None) -> str:
+    kwargs: dict[str, object] = {"conference_slug": conference_slug}
+    if pk is not None:
+        kwargs["pk"] = pk
+    return reverse(f"manage:{name}", kwargs=kwargs)
+
+
+# ---------------------------------------------------------------------------
+# List view
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.integration
+@pytest.mark.django_db
+class TestPurchaseOrderListView:
+    def test_purchase_order_list_view(self, logged_in_client, conference, purchase_order) -> None:
+        url = _po_url("purchase-order-list", conference.slug)
+        resp = logged_in_client.get(url)
+        assert resp.status_code == 200
+        assert purchase_order in resp.context["purchase_orders"]
+
+    def test_purchase_order_list_status_filter(self, logged_in_client, conference, purchase_order) -> None:
+        url = _po_url("purchase-order-list", conference.slug) + "?status=draft"
+        resp = logged_in_client.get(url)
+        assert resp.status_code == 200
+        assert purchase_order in resp.context["purchase_orders"]
+
+        url_sent = _po_url("purchase-order-list", conference.slug) + "?status=sent"
+        resp_sent = logged_in_client.get(url_sent)
+        assert resp_sent.status_code == 200
+        assert purchase_order not in resp_sent.context["purchase_orders"]
+
+
+# ---------------------------------------------------------------------------
+# Detail view
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.integration
+@pytest.mark.django_db
+class TestPurchaseOrderDetailView:
+    def test_purchase_order_detail_view(self, logged_in_client, conference, purchase_order) -> None:
+        url = _po_url("purchase-order-detail", conference.slug, purchase_order.pk)
+        resp = logged_in_client.get(url)
+        assert resp.status_code == 200
+        assert resp.context["purchase_order"] == purchase_order
+
+
+# ---------------------------------------------------------------------------
+# Create view
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.integration
+@pytest.mark.django_db
+class TestPurchaseOrderCreateView:
+    def test_purchase_order_create_get(self, logged_in_client, conference) -> None:
+        url = _po_url("purchase-order-add", conference.slug)
+        resp = logged_in_client.get(url)
+        assert resp.status_code == 200
+
+    def test_purchase_order_create_post(self, logged_in_client, conference) -> None:
+        url = _po_url("purchase-order-add", conference.slug)
+        resp = logged_in_client.post(
+            url,
+            {
+                "organization_name": "NewOrg",
+                "contact_email": "new@org.com",
+                "contact_name": "Bob",
+                "billing_address": "456 Elm St",
+                "notes": "",
+                "line_description": ["Widget"],
+                "line_quantity": ["2"],
+                "line_unit_price": ["100.00"],
+            },
+        )
+        assert resp.status_code == 302
+        po = PurchaseOrder.objects.get(organization_name="NewOrg")
+        assert po.total == Decimal("200.00")
+
+    def test_purchase_order_create_post_validation(self, logged_in_client, conference) -> None:
+        url = _po_url("purchase-order-add", conference.slug)
+        resp = logged_in_client.post(
+            url,
+            {
+                "organization_name": "",
+                "contact_email": "",
+                "contact_name": "",
+                "line_description": [],
+                "line_quantity": [],
+                "line_unit_price": [],
+            },
+        )
+        # Re-renders the form (200), not a redirect
+        assert resp.status_code == 200
+
+    def test_purchase_order_create_post_blank_line_description(self, logged_in_client, conference) -> None:
+        url = _po_url("purchase-order-add", conference.slug)
+        resp = logged_in_client.post(
+            url,
+            {
+                "organization_name": "BlankLineOrg",
+                "contact_email": "blank@org.com",
+                "contact_name": "Blank",
+                "line_description": ["", "Widget"],
+                "line_quantity": ["1", "2"],
+                "line_unit_price": ["10.00", "50.00"],
+            },
+        )
+        assert resp.status_code == 302
+        po = PurchaseOrder.objects.get(organization_name="BlankLineOrg")
+        # Only the non-blank line item should be created
+        assert po.line_items.count() == 1
+        assert po.total == Decimal("100.00")
+
+    def test_purchase_order_create_post_invalid_line_items(self, logged_in_client, conference) -> None:
+        url = _po_url("purchase-order-add", conference.slug)
+        resp = logged_in_client.post(
+            url,
+            {
+                "organization_name": "ValidOrg",
+                "contact_email": "valid@org.com",
+                "contact_name": "Valid",
+                "line_description": ["Widget", "Gadget", "Doohickey"],
+                "line_quantity": ["abc", "0", "2"],
+                "line_unit_price": ["10.00", "20.00", "-5.00"],
+            },
+        )
+        # Re-renders with errors (invalid qty, qty < 1, negative price)
+        assert resp.status_code == 200
+
+    def test_purchase_order_create_post_service_exception(self, logged_in_client, conference) -> None:
+        url = _po_url("purchase-order-add", conference.slug)
+        with patch(
+            "django_program.manage.views_purchase_orders.create_purchase_order",
+            side_effect=RuntimeError("DB error"),
+        ):
+            resp = logged_in_client.post(
+                url,
+                {
+                    "organization_name": "ExcOrg",
+                    "contact_email": "exc@org.com",
+                    "contact_name": "Exc",
+                    "line_description": ["Item"],
+                    "line_quantity": ["1"],
+                    "line_unit_price": ["50.00"],
+                },
+            )
+        assert resp.status_code == 302
+
+
+# ---------------------------------------------------------------------------
+# Record payment view
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.integration
+@pytest.mark.django_db
+class TestPurchaseOrderRecordPaymentView:
+    def test_purchase_order_record_payment(self, logged_in_client, conference, purchase_order) -> None:
+        url = _po_url("purchase-order-payment", conference.slug, purchase_order.pk)
+        resp = logged_in_client.post(
+            url,
+            {
+                "amount": "500.00",
+                "method": "wire",
+                "reference": "WIRE-001",
+                "note": "First payment",
+                "payment_date": "2027-06-01",
+            },
+        )
+        assert resp.status_code == 302
+        purchase_order.refresh_from_db()
+        assert purchase_order.total_paid == Decimal("500.00")
+
+    def test_purchase_order_record_payment_invalid_method(self, logged_in_client, conference, purchase_order) -> None:
+        url = _po_url("purchase-order-payment", conference.slug, purchase_order.pk)
+        resp = logged_in_client.post(
+            url,
+            {"amount": "100.00", "method": "invalid_method", "payment_date": "2027-06-01"},
+        )
+        assert resp.status_code == 302
+        purchase_order.refresh_from_db()
+        assert purchase_order.total_paid == Decimal("100.00")
+
+    def test_purchase_order_record_payment_invalid_amount(self, logged_in_client, conference, purchase_order) -> None:
+        url = _po_url("purchase-order-payment", conference.slug, purchase_order.pk)
+        resp = logged_in_client.post(url, {"amount": "not-a-number", "method": "wire"})
+        assert resp.status_code == 302
+        purchase_order.refresh_from_db()
+        assert purchase_order.total_paid == Decimal("0.00")
+
+    def test_purchase_order_record_payment_zero_amount(self, logged_in_client, conference, purchase_order) -> None:
+        url = _po_url("purchase-order-payment", conference.slug, purchase_order.pk)
+        resp = logged_in_client.post(url, {"amount": "0", "method": "wire"})
+        assert resp.status_code == 302
+        purchase_order.refresh_from_db()
+        assert purchase_order.total_paid == Decimal("0.00")
+
+    def test_purchase_order_record_payment_invalid_date(self, logged_in_client, conference, purchase_order) -> None:
+        url = _po_url("purchase-order-payment", conference.slug, purchase_order.pk)
+        resp = logged_in_client.post(
+            url,
+            {"amount": "100.00", "method": "wire", "payment_date": "not-a-date"},
+        )
+        assert resp.status_code == 302
+        purchase_order.refresh_from_db()
+        assert purchase_order.total_paid == Decimal("100.00")
+
+    def test_purchase_order_record_payment_exception(self, logged_in_client, conference, purchase_order) -> None:
+        url = _po_url("purchase-order-payment", conference.slug, purchase_order.pk)
+        with patch(
+            "django_program.manage.views_purchase_orders.record_payment",
+            side_effect=RuntimeError("DB error"),
+        ):
+            resp = logged_in_client.post(url, {"amount": "100.00", "method": "wire"})
+        assert resp.status_code == 302
+        purchase_order.refresh_from_db()
+        assert purchase_order.total_paid == Decimal("0.00")
+
+    def test_purchase_order_record_payment_cancelled(self, logged_in_client, conference, purchase_order) -> None:
+        purchase_order.status = PurchaseOrder.Status.CANCELLED
+        purchase_order.save(update_fields=["status"])
+
+        url = _po_url("purchase-order-payment", conference.slug, purchase_order.pk)
+        resp = logged_in_client.post(url, {"amount": "100.00", "method": "wire"})
+        assert resp.status_code == 302
+        purchase_order.refresh_from_db()
+        assert purchase_order.total_paid == Decimal("0.00")
+
+
+# ---------------------------------------------------------------------------
+# Issue credit view
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.integration
+@pytest.mark.django_db
+class TestPurchaseOrderIssueCreditView:
+    def test_purchase_order_issue_credit(self, logged_in_client, conference, purchase_order) -> None:
+        url = _po_url("purchase-order-credit", conference.slug, purchase_order.pk)
+        resp = logged_in_client.post(
+            url,
+            {"amount": "200.00", "reason": "Comp discount"},
+        )
+        assert resp.status_code == 302
+        purchase_order.refresh_from_db()
+        assert purchase_order.balance_due == Decimal("1050.00")
+
+    def test_purchase_order_issue_credit_invalid_amount(self, logged_in_client, conference, purchase_order) -> None:
+        url = _po_url("purchase-order-credit", conference.slug, purchase_order.pk)
+        resp = logged_in_client.post(url, {"amount": "bad", "reason": "Test"})
+        assert resp.status_code == 302
+        assert purchase_order.credit_notes.count() == 0
+
+    def test_purchase_order_issue_credit_zero_amount(self, logged_in_client, conference, purchase_order) -> None:
+        url = _po_url("purchase-order-credit", conference.slug, purchase_order.pk)
+        resp = logged_in_client.post(url, {"amount": "0", "reason": "Test"})
+        assert resp.status_code == 302
+        assert purchase_order.credit_notes.count() == 0
+
+    def test_purchase_order_issue_credit_missing_reason(self, logged_in_client, conference, purchase_order) -> None:
+        url = _po_url("purchase-order-credit", conference.slug, purchase_order.pk)
+        resp = logged_in_client.post(url, {"amount": "100.00", "reason": ""})
+        assert resp.status_code == 302
+        assert purchase_order.credit_notes.count() == 0
+
+    def test_purchase_order_issue_credit_exception(self, logged_in_client, conference, purchase_order) -> None:
+        url = _po_url("purchase-order-credit", conference.slug, purchase_order.pk)
+        with patch(
+            "django_program.manage.views_purchase_orders.issue_credit_note",
+            side_effect=RuntimeError("DB error"),
+        ):
+            resp = logged_in_client.post(url, {"amount": "100.00", "reason": "Reason"})
+        assert resp.status_code == 302
+        assert purchase_order.credit_notes.count() == 0
+
+    def test_purchase_order_issue_credit_cancelled(self, logged_in_client, conference, purchase_order) -> None:
+        purchase_order.status = PurchaseOrder.Status.CANCELLED
+        purchase_order.save(update_fields=["status"])
+
+        url = _po_url("purchase-order-credit", conference.slug, purchase_order.pk)
+        resp = logged_in_client.post(url, {"amount": "100.00", "reason": "Test"})
+        assert resp.status_code == 302
+        # No credit notes should have been created
+        assert purchase_order.credit_notes.count() == 0
+
+
+# ---------------------------------------------------------------------------
+# Cancel view
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.integration
+@pytest.mark.django_db
+class TestPurchaseOrderCancelView:
+    def test_purchase_order_cancel(self, logged_in_client, conference, purchase_order) -> None:
+        url = _po_url("purchase-order-cancel", conference.slug, purchase_order.pk)
+        resp = logged_in_client.post(url)
+        assert resp.status_code == 302
+        purchase_order.refresh_from_db()
+        assert purchase_order.status == PurchaseOrder.Status.CANCELLED
+
+    def test_purchase_order_cancel_already_cancelled(self, logged_in_client, conference, purchase_order) -> None:
+        purchase_order.status = PurchaseOrder.Status.CANCELLED
+        purchase_order.save(update_fields=["status"])
+        url = _po_url("purchase-order-cancel", conference.slug, purchase_order.pk)
+        resp = logged_in_client.post(url)
+        assert resp.status_code == 302
+
+    def test_purchase_order_cancel_paid(self, logged_in_client, conference, purchase_order) -> None:
+        purchase_order.status = PurchaseOrder.Status.PAID
+        purchase_order.save(update_fields=["status"])
+        url = _po_url("purchase-order-cancel", conference.slug, purchase_order.pk)
+        resp = logged_in_client.post(url)
+        assert resp.status_code == 302
+        purchase_order.refresh_from_db()
+        assert purchase_order.status == PurchaseOrder.Status.PAID
+
+    def test_purchase_order_cancel_exception(self, logged_in_client, conference, purchase_order) -> None:
+        url = _po_url("purchase-order-cancel", conference.slug, purchase_order.pk)
+        with patch(
+            "django_program.manage.views_purchase_orders.cancel_purchase_order",
+            side_effect=RuntimeError("DB error"),
+        ):
+            resp = logged_in_client.post(url)
+        assert resp.status_code == 302
+
+
+# ---------------------------------------------------------------------------
+# Send view
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.integration
+@pytest.mark.django_db
+class TestPurchaseOrderSendView:
+    def test_purchase_order_send(self, logged_in_client, conference, purchase_order) -> None:
+        url = _po_url("purchase-order-send", conference.slug, purchase_order.pk)
+        resp = logged_in_client.post(url)
+        assert resp.status_code == 302
+        purchase_order.refresh_from_db()
+        assert purchase_order.status == PurchaseOrder.Status.SENT
+
+    def test_purchase_order_send_non_draft_shows_error(self, logged_in_client, conference, purchase_order) -> None:
+        send_purchase_order(purchase_order)
+        purchase_order.refresh_from_db()
+        assert purchase_order.status == PurchaseOrder.Status.SENT
+
+        url = _po_url("purchase-order-send", conference.slug, purchase_order.pk)
+        resp = logged_in_client.post(url)
+        assert resp.status_code == 302
+
+    def test_purchase_order_send_exception(self, logged_in_client, conference, purchase_order) -> None:
+        url = _po_url("purchase-order-send", conference.slug, purchase_order.pk)
+        with patch(
+            "django_program.manage.views_purchase_orders.send_purchase_order",
+            side_effect=RuntimeError("DB error"),
+        ):
+            resp = logged_in_client.post(url)
+        assert resp.status_code == 302
+
+
+# ---------------------------------------------------------------------------
+# Invoice PDF view
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.integration
+@pytest.mark.django_db
+class TestPurchaseOrderInvoiceView:
+    def test_purchase_order_invoice_pdf(self, logged_in_client, conference, purchase_order) -> None:
+        url = _po_url("purchase-order-invoice", conference.slug, purchase_order.pk)
+        resp = logged_in_client.get(url)
+        assert resp.status_code == 200
+        assert resp["Content-Type"] == "application/pdf"
+        assert "attachment" in resp["Content-Disposition"]
+        assert purchase_order.reference in resp["Content-Disposition"]
+
+
+# ---------------------------------------------------------------------------
+# Stripe invoice view
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.integration
+@pytest.mark.django_db
+class TestPurchaseOrderStripeInvoiceView:
+    def test_stripe_invoice_creates_and_redirects(self, logged_in_client, conference, purchase_order) -> None:
+        url = _po_url("purchase-order-stripe-invoice", conference.slug, purchase_order.pk)
+        with patch(
+            "django_program.manage.views_purchase_orders.create_stripe_invoice",
+            return_value="https://invoice.stripe.com/i/test",
+        ):
+            resp = logged_in_client.post(url)
+        assert resp.status_code == 302
+        purchase_order.refresh_from_db()
+        assert purchase_order.status == PurchaseOrder.Status.SENT
+
+    def test_stripe_invoice_invalid_status(self, logged_in_client, conference, purchase_order) -> None:
+        purchase_order.status = PurchaseOrder.Status.CANCELLED
+        purchase_order.save(update_fields=["status"])
+
+        url = _po_url("purchase-order-stripe-invoice", conference.slug, purchase_order.pk)
+        resp = logged_in_client.post(url)
+        assert resp.status_code == 302
+
+    def test_stripe_invoice_value_error(self, logged_in_client, conference, purchase_order) -> None:
+        url = _po_url("purchase-order-stripe-invoice", conference.slug, purchase_order.pk)
+        with patch(
+            "django_program.manage.views_purchase_orders.create_stripe_invoice",
+            side_effect=ValueError("already has a Stripe invoice"),
+        ):
+            resp = logged_in_client.post(url)
+        assert resp.status_code == 302
+
+    def test_stripe_invoice_general_exception(self, logged_in_client, conference, purchase_order) -> None:
+        url = _po_url("purchase-order-stripe-invoice", conference.slug, purchase_order.pk)
+        with patch(
+            "django_program.manage.views_purchase_orders.create_stripe_invoice",
+            side_effect=RuntimeError("Stripe API down"),
+        ):
+            resp = logged_in_client.post(url)
+        assert resp.status_code == 302
+
+
+# ---------------------------------------------------------------------------
+# QBO invoice view
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.integration
+@pytest.mark.django_db
+class TestPurchaseOrderQBOInvoiceView:
+    def test_qbo_invoice_creates_and_redirects(self, logged_in_client, conference, purchase_order) -> None:
+        url = _po_url("purchase-order-qbo-invoice", conference.slug, purchase_order.pk)
+        with (
+            patch("django_program.manage.views_purchase_orders.create_qbo_invoice"),
+            patch("django_program.manage.views_purchase_orders.send_qbo_invoice_email"),
+        ):
+            resp = logged_in_client.post(url)
+        assert resp.status_code == 302
+        purchase_order.refresh_from_db()
+        assert purchase_order.status == PurchaseOrder.Status.SENT
+
+    def test_qbo_invoice_invalid_status(self, logged_in_client, conference, purchase_order) -> None:
+        purchase_order.status = PurchaseOrder.Status.CANCELLED
+        purchase_order.save(update_fields=["status"])
+
+        url = _po_url("purchase-order-qbo-invoice", conference.slug, purchase_order.pk)
+        resp = logged_in_client.post(url)
+        assert resp.status_code == 302
+
+    def test_qbo_invoice_already_exists(self, logged_in_client, conference, purchase_order) -> None:
+        purchase_order.qbo_invoice_id = "123"
+        purchase_order.save(update_fields=["qbo_invoice_id"])
+
+        url = _po_url("purchase-order-qbo-invoice", conference.slug, purchase_order.pk)
+        resp = logged_in_client.post(url)
+        assert resp.status_code == 302
+
+    def test_qbo_invoice_not_configured(self, logged_in_client, conference, purchase_order) -> None:
+        from django_program.registration.services.qbo_invoicing import QBONotConfiguredError
+
+        url = _po_url("purchase-order-qbo-invoice", conference.slug, purchase_order.pk)
+        with patch(
+            "django_program.manage.views_purchase_orders.create_qbo_invoice",
+            side_effect=QBONotConfiguredError("not configured"),
+        ):
+            resp = logged_in_client.post(url)
+        assert resp.status_code == 302
+
+    def test_qbo_invoice_api_error(self, logged_in_client, conference, purchase_order) -> None:
+        from django_program.registration.services.qbo_invoicing import QBOAPIError
+
+        url = _po_url("purchase-order-qbo-invoice", conference.slug, purchase_order.pk)
+        with patch(
+            "django_program.manage.views_purchase_orders.create_qbo_invoice",
+            side_effect=QBOAPIError(400, "Bad request"),
+        ):
+            resp = logged_in_client.post(url)
+        assert resp.status_code == 302
+
+    def test_qbo_invoice_general_exception(self, logged_in_client, conference, purchase_order) -> None:
+        url = _po_url("purchase-order-qbo-invoice", conference.slug, purchase_order.pk)
+        with patch(
+            "django_program.manage.views_purchase_orders.create_qbo_invoice",
+            side_effect=RuntimeError("QBO down"),
+        ):
+            resp = logged_in_client.post(url)
+        assert resp.status_code == 302
diff --git a/tests/test_registration/test_qbo_invoicing.py b/tests/test_registration/test_qbo_invoicing.py
new file mode 100644
index 0000000..7157a52
--- /dev/null
+++ b/tests/test_registration/test_qbo_invoicing.py
@@ -0,0 +1,514 @@
+"""Tests for QuickBooks Online invoicing integration with purchase orders."""
+
+from datetime import date, timedelta
+from decimal import Decimal
+from unittest.mock import MagicMock, patch
+
+import pytest
+from django.contrib.auth import get_user_model
+from django.utils import timezone
+
+from django_program.conference.models import Conference
+from django_program.registration.models import TicketType
+from django_program.registration.purchase_order import PurchaseOrder
+from django_program.registration.services.purchase_orders import create_purchase_order
+from django_program.registration.services.qbo_invoicing import (
+    QBOAPIError,
+    QBONotConfiguredError,
+    _check_response,
+    _refresh_token_if_needed,
+    create_qbo_invoice,
+    handle_qbo_webhook,
+    send_qbo_invoice_email,
+    sync_qbo_invoice_status,
+)
+
+User = get_user_model()
+
+
+# ---------------------------------------------------------------------------
+# Fixtures
+# ---------------------------------------------------------------------------
+
+
+@pytest.fixture
+def conference(db) -> Conference:
+    return Conference.objects.create(
+        name="QBO Inv Conf",
+        slug="qbo-inv-conf",
+        start_date=date(2027, 7, 1),
+        end_date=date(2027, 7, 3),
+        timezone="UTC",
+        qbo_realm_id="1234567890",
+        qbo_access_token="qbo_access_fake",
+        qbo_refresh_token="qbo_refresh_fake",
+        qbo_client_id="qbo_client_id_fake",
+        qbo_client_secret="qbo_client_secret_fake",
+        qbo_token_expires_at=timezone.now() + timedelta(hours=1),
+    )
+
+
+@pytest.fixture
+def staff_user(db) -> User:
+    return User.objects.create_user(username="qboinvstaff", email="qboinv@test.com", password="testpass123")
+
+
+@pytest.fixture
+def ticket_type(conference) -> TicketType:
+    return TicketType.objects.create(
+        conference=conference,
+        name="Corporate",
+        slug="corporate-qbo",
+        price=Decimal("300.00"),
+        total_quantity=0,
+        limit_per_user=10,
+        is_active=True,
+    )
+
+
+@pytest.fixture
+def purchase_order(conference, staff_user, ticket_type) -> PurchaseOrder:
+    return create_purchase_order(
+        conference=conference,
+        organization_name="QBO Test Org",
+        contact_email="billing@qbo-test.com",
+        contact_name="QBO Person",
+        billing_address="100 Invoice Rd\nSuite 200\nPortland",
+        line_items=[
+            {
+                "description": "Corporate Ticket",
+                "quantity": 4,
+                "unit_price": Decimal("300.00"),
+                "ticket_type": ticket_type,
+            },
+        ],
+        created_by=staff_user,
+    )
+
+
+def _mock_httpx_response(status_code: int = 200, json_data: dict | None = None) -> MagicMock:
+    resp = MagicMock()
+    resp.status_code = status_code
+    resp.json.return_value = json_data or {}
+    resp.text = ""
+    return resp
+
+
+# ---------------------------------------------------------------------------
+# create_qbo_invoice
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.integration
+@pytest.mark.django_db
+class TestCreateQBOInvoice:
+    def test_create_qbo_invoice(self, purchase_order) -> None:
+        # Customer query returns empty (needs creation), then create returns customer
+        query_resp = _mock_httpx_response(json_data={"QueryResponse": {"Customer": []}})
+        create_customer_resp = _mock_httpx_response(json_data={"Customer": {"Id": "42"}})
+        create_invoice_resp = _mock_httpx_response(json_data={"Invoice": {"Id": "INV-99"}})
+
+        with patch("django_program.registration.services.qbo_invoicing.httpx") as mock_httpx:
+            mock_httpx.get.return_value = query_resp
+            mock_httpx.post.side_effect = [create_customer_resp, create_invoice_resp]
+
+            invoice_id = create_qbo_invoice(purchase_order)
+
+        assert invoice_id == "INV-99"
+        purchase_order.refresh_from_db()
+        assert purchase_order.qbo_invoice_id == "INV-99"
+        assert "INV-99" in purchase_order.qbo_invoice_url
+
+    def test_create_qbo_invoice_not_configured(self, staff_user) -> None:
+        conf = Conference.objects.create(
+            name="No QBO Conf",
+            slug="no-qbo-conf",
+            start_date=date(2027, 8, 1),
+            end_date=date(2027, 8, 3),
+            timezone="UTC",
+        )
+        po = create_purchase_order(
+            conference=conf,
+            organization_name="NoQBO Org",
+            contact_email="noqbo@test.com",
+            contact_name="NoQBO",
+            line_items=[{"description": "Item", "quantity": 1, "unit_price": Decimal("50.00")}],
+            created_by=staff_user,
+        )
+
+        with pytest.raises(QBONotConfiguredError):
+            create_qbo_invoice(po)
+
+    def test_create_qbo_invoice_already_exists(self, purchase_order) -> None:
+        purchase_order.qbo_invoice_id = "INV-EXISTING"
+        purchase_order.save(update_fields=["qbo_invoice_id"])
+
+        with pytest.raises(ValueError, match="already has QBO invoice"):
+            create_qbo_invoice(purchase_order)
+
+    def test_create_qbo_invoice_customer_no_id(self, purchase_order) -> None:
+        query_resp = _mock_httpx_response(json_data={"QueryResponse": {"Customer": []}})
+        # Customer creation returns empty Id
+        create_customer_resp = _mock_httpx_response(json_data={"Customer": {"Id": ""}})
+
+        with patch("django_program.registration.services.qbo_invoicing.httpx") as mock_httpx:
+            mock_httpx.get.return_value = query_resp
+            mock_httpx.post.return_value = create_customer_resp
+
+            with pytest.raises(QBOAPIError, match="without an Id"):
+                create_qbo_invoice(purchase_order)
+
+    def test_create_qbo_invoice_no_invoice_id_returned(self, purchase_order) -> None:
+        query_resp = _mock_httpx_response(json_data={"QueryResponse": {"Customer": [{"Id": "42"}]}})
+        # Invoice creation returns empty Id
+        create_invoice_resp = _mock_httpx_response(json_data={"Invoice": {"Id": ""}})
+
+        with patch("django_program.registration.services.qbo_invoicing.httpx") as mock_httpx:
+            mock_httpx.get.return_value = query_resp
+            mock_httpx.post.return_value = create_invoice_resp
+
+            with pytest.raises(QBOAPIError, match="without an Id"):
+                create_qbo_invoice(purchase_order)
+
+    def test_create_qbo_invoice_existing_customer(self, purchase_order) -> None:
+        # Customer query returns an existing customer
+        query_resp = _mock_httpx_response(json_data={"QueryResponse": {"Customer": [{"Id": "77"}]}})
+        create_invoice_resp = _mock_httpx_response(json_data={"Invoice": {"Id": "INV-200"}})
+
+        with patch("django_program.registration.services.qbo_invoicing.httpx") as mock_httpx:
+            mock_httpx.get.return_value = query_resp
+            mock_httpx.post.return_value = create_invoice_resp
+
+            invoice_id = create_qbo_invoice(purchase_order)
+
+        assert invoice_id == "INV-200"
+        # httpx.post should only be called once (for invoice, not customer creation)
+        assert mock_httpx.post.call_count == 1
+
+
+# ---------------------------------------------------------------------------
+# sync_qbo_invoice_status
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.integration
+@pytest.mark.django_db
+class TestSyncQBOInvoiceStatus:
+    def test_sync_qbo_invoice_status_paid(self, purchase_order) -> None:
+        purchase_order.qbo_invoice_id = "INV-SYNC"
+        purchase_order.status = PurchaseOrder.Status.SENT
+        purchase_order.save(update_fields=["qbo_invoice_id", "status"])
+
+        invoice_resp = _mock_httpx_response(
+            json_data={"Invoice": {"Balance": 0, "TotalAmt": 1200.00}},
+        )
+
+        with patch("django_program.registration.services.qbo_invoicing.httpx") as mock_httpx:
+            mock_httpx.get.return_value = invoice_resp
+            sync_qbo_invoice_status(purchase_order)
+
+        purchase_order.refresh_from_db()
+        assert purchase_order.total_paid == Decimal("1200.00")
+        assert purchase_order.status == PurchaseOrder.Status.PAID
+
+    def test_sync_qbo_invoice_no_invoice_id(self, purchase_order) -> None:
+        with pytest.raises(ValueError, match="no QBO invoice"):
+            sync_qbo_invoice_status(purchase_order)
+
+    def test_sync_qbo_invoice_not_yet_paid(self, purchase_order) -> None:
+        purchase_order.qbo_invoice_id = "INV-UNPAID"
+        purchase_order.status = PurchaseOrder.Status.SENT
+        purchase_order.save(update_fields=["qbo_invoice_id", "status"])
+
+        invoice_resp = _mock_httpx_response(
+            json_data={"Invoice": {"Balance": 600.00, "TotalAmt": 1200.00}},
+        )
+
+        with patch("django_program.registration.services.qbo_invoicing.httpx") as mock_httpx:
+            mock_httpx.get.return_value = invoice_resp
+            sync_qbo_invoice_status(purchase_order)
+
+        purchase_order.refresh_from_db()
+        assert purchase_order.total_paid == Decimal("0.00")
+        assert purchase_order.status == PurchaseOrder.Status.SENT
+
+
+# ---------------------------------------------------------------------------
+# Token refresh
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.integration
+@pytest.mark.django_db
+class TestQBOTokenRefresh:
+    def test_qbo_token_refresh(self, purchase_order, conference) -> None:
+        # Set token as expired
+        conference.qbo_token_expires_at = timezone.now() - timedelta(minutes=10)
+        conference.save(update_fields=["qbo_token_expires_at"])
+
+        purchase_order.qbo_invoice_id = "INV-REFRESH"
+        purchase_order.status = PurchaseOrder.Status.SENT
+        purchase_order.save(update_fields=["qbo_invoice_id", "status"])
+
+        # Token refresh response
+        token_resp = _mock_httpx_response(
+            json_data={
+                "access_token": "new_access_token",
+                "refresh_token": "new_refresh_token",
+                "expires_in": 3600,
+            },
+        )
+        # Invoice status response (paid)
+        invoice_resp = _mock_httpx_response(
+            json_data={"Invoice": {"Balance": 0, "TotalAmt": 1200.00}},
+        )
+
+        with patch("django_program.registration.services.qbo_invoicing.httpx") as mock_httpx:
+            # First call is POST (token refresh), second is GET (invoice fetch)
+            mock_httpx.post.return_value = token_resp
+            mock_httpx.get.return_value = invoice_resp
+
+            sync_qbo_invoice_status(purchase_order)
+
+        conference.refresh_from_db()
+        assert str(conference.qbo_access_token) == "new_access_token"
+        assert str(conference.qbo_refresh_token) == "new_refresh_token"
+
+        purchase_order.refresh_from_db()
+        assert purchase_order.total_paid == Decimal("1200.00")
+
+    def test_qbo_token_refresh_incomplete_credentials(self, conference) -> None:
+        """When refresh credentials are missing, the expired token is returned as-is."""
+        conference.qbo_token_expires_at = timezone.now() - timedelta(minutes=10)
+        conference.qbo_client_id = ""
+        conference.qbo_client_secret = ""
+        conference.save(update_fields=["qbo_token_expires_at", "qbo_client_id", "qbo_client_secret"])
+
+        token = _refresh_token_if_needed(conference)
+        assert token == str(conference.qbo_access_token)
+
+
+# ---------------------------------------------------------------------------
+# QBOAPIError and _check_response
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.unit
+class TestQBOAPIError:
+    def test_error_attributes(self) -> None:
+        err = QBOAPIError(400, "Bad request")
+        assert err.status_code == 400
+        assert err.detail == "Bad request"
+        assert "400" in str(err)
+        assert "Bad request" in str(err)
+
+    def test_check_response_raises_on_error(self) -> None:
+        resp = MagicMock()
+        resp.status_code = 401
+        resp.text = "Unauthorized"
+        with pytest.raises(QBOAPIError) as exc_info:
+            _check_response(resp)
+        assert exc_info.value.status_code == 401
+
+    def test_check_response_ok(self) -> None:
+        resp = MagicMock()
+        resp.status_code = 200
+        _check_response(resp)  # Should not raise
+
+
+# ---------------------------------------------------------------------------
+# send_qbo_invoice_email
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.integration
+@pytest.mark.django_db
+class TestSendQBOInvoiceEmail:
+    def test_send_qbo_invoice_email(self, purchase_order) -> None:
+        purchase_order.qbo_invoice_id = "INV-SEND"
+        purchase_order.save(update_fields=["qbo_invoice_id"])
+
+        send_resp = _mock_httpx_response()
+
+        with patch("django_program.registration.services.qbo_invoicing.httpx") as mock_httpx:
+            mock_httpx.post.return_value = send_resp
+            send_qbo_invoice_email(purchase_order)
+
+        mock_httpx.post.assert_called_once()
+
+    def test_send_qbo_invoice_email_no_invoice_id(self, purchase_order) -> None:
+        with pytest.raises(ValueError, match="no QBO invoice"):
+            send_qbo_invoice_email(purchase_order)
+
+
+# ---------------------------------------------------------------------------
+# handle_qbo_webhook
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.integration
+@pytest.mark.django_db
+class TestHandleQBOWebhook:
+    def test_handle_qbo_webhook_payment_event(self, purchase_order, conference) -> None:
+        purchase_order.qbo_invoice_id = "INV-WH"
+        purchase_order.status = PurchaseOrder.Status.SENT
+        purchase_order.save(update_fields=["qbo_invoice_id", "status"])
+
+        invoice_resp = _mock_httpx_response(
+            json_data={"Invoice": {"Balance": 0, "TotalAmt": 1200.00}},
+        )
+
+        payload = {
+            "eventNotifications": [
+                {
+                    "realmId": str(conference.qbo_realm_id),
+                    "dataChangeEvent": {
+                        "entities": [
+                            {"name": "Payment", "operation": "Create"},
+                        ],
+                    },
+                },
+            ],
+        }
+
+        with patch("django_program.registration.services.qbo_invoicing.httpx") as mock_httpx:
+            mock_httpx.get.return_value = invoice_resp
+            handle_qbo_webhook(payload)
+
+        purchase_order.refresh_from_db()
+        assert purchase_order.total_paid == Decimal("1200.00")
+
+    def test_handle_qbo_webhook_non_payment_event(self) -> None:
+        payload = {
+            "eventNotifications": [
+                {
+                    "realmId": "999",
+                    "dataChangeEvent": {
+                        "entities": [
+                            {"name": "Invoice", "operation": "Create"},
+                        ],
+                    },
+                },
+            ],
+        }
+        handle_qbo_webhook(payload)
+
+    def test_handle_qbo_webhook_bad_payload(self) -> None:
+        handle_qbo_webhook({"eventNotifications": "not_a_list"})
+        handle_qbo_webhook({})
+
+    def test_handle_qbo_webhook_bad_notification(self) -> None:
+        handle_qbo_webhook({"eventNotifications": ["not_a_dict"]})
+
+    def test_handle_qbo_webhook_missing_realm_id(self) -> None:
+        payload = {
+            "eventNotifications": [
+                {
+                    "dataChangeEvent": {
+                        "entities": [
+                            {"name": "Payment", "operation": "Create"},
+                        ],
+                    },
+                },
+            ],
+        }
+        handle_qbo_webhook(payload)
+
+    def test_handle_qbo_webhook_bad_data_change_event(self) -> None:
+        payload = {
+            "eventNotifications": [
+                {
+                    "realmId": "999",
+                    "dataChangeEvent": "not_a_dict",
+                },
+            ],
+        }
+        handle_qbo_webhook(payload)
+
+    def test_handle_qbo_webhook_bad_entities(self) -> None:
+        payload = {
+            "eventNotifications": [
+                {
+                    "realmId": "999",
+                    "dataChangeEvent": {
+                        "entities": "not_a_list",
+                    },
+                },
+            ],
+        }
+        handle_qbo_webhook(payload)
+
+    def test_handle_qbo_webhook_sync_failure(self, purchase_order, conference) -> None:
+        """When sync fails for a PO, it logs the exception and continues."""
+        purchase_order.qbo_invoice_id = "INV-FAIL"
+        purchase_order.status = PurchaseOrder.Status.SENT
+        purchase_order.save(update_fields=["qbo_invoice_id", "status"])
+
+        payload = {
+            "eventNotifications": [
+                {
+                    "realmId": str(conference.qbo_realm_id),
+                    "dataChangeEvent": {
+                        "entities": [
+                            {"name": "Payment", "operation": "Update"},
+                        ],
+                    },
+                },
+            ],
+        }
+
+        with patch(
+            "django_program.registration.services.qbo_invoicing.sync_qbo_invoice_status",
+            side_effect=RuntimeError("API failure"),
+        ):
+            handle_qbo_webhook(payload)
+
+    def test_handle_qbo_webhook_many_pos_warning(self, conference, staff_user, ticket_type) -> None:
+        """When there are more POs than _WEBHOOK_SYNC_LIMIT, a warning is logged."""
+        with patch("django_program.registration.services.qbo_invoicing._WEBHOOK_SYNC_LIMIT", 1):
+            for i in range(2):
+                po = create_purchase_order(
+                    conference=conference,
+                    organization_name=f"Org {i}",
+                    contact_email=f"org{i}@test.com",
+                    contact_name=f"Person {i}",
+                    line_items=[{"description": "Ticket", "quantity": 1, "unit_price": Decimal("100.00")}],
+                    created_by=staff_user,
+                )
+                po.qbo_invoice_id = f"INV-MANY-{i}"
+                po.status = PurchaseOrder.Status.SENT
+                po.save(update_fields=["qbo_invoice_id", "status"])
+
+            invoice_resp = _mock_httpx_response(
+                json_data={"Invoice": {"Balance": 0, "TotalAmt": 100.00}},
+            )
+
+            payload = {
+                "eventNotifications": [
+                    {
+                        "realmId": str(conference.qbo_realm_id),
+                        "dataChangeEvent": {
+                            "entities": [
+                                {"name": "Payment", "operation": "Create"},
+                            ],
+                        },
+                    },
+                ],
+            }
+
+            with patch("django_program.registration.services.qbo_invoicing.httpx") as mock_httpx:
+                mock_httpx.get.return_value = invoice_resp
+                handle_qbo_webhook(payload)
+
+    def test_handle_qbo_webhook_bad_entity(self) -> None:
+        payload = {
+            "eventNotifications": [
+                {
+                    "realmId": "999",
+                    "dataChangeEvent": {
+                        "entities": ["not_a_dict"],
+                    },
+                },
+            ],
+        }
+        handle_qbo_webhook(payload)
diff --git a/tests/test_registration/test_stripe_invoicing.py b/tests/test_registration/test_stripe_invoicing.py
new file mode 100644
index 0000000..5228d7f
--- /dev/null
+++ b/tests/test_registration/test_stripe_invoicing.py
@@ -0,0 +1,400 @@
+"""Tests for Stripe invoicing integration with purchase orders."""
+
+from datetime import date
+from decimal import Decimal
+from unittest.mock import MagicMock, patch
+
+import pytest
+from django.contrib.auth import get_user_model
+
+from django_program.conference.models import Conference
+from django_program.registration.models import TicketType
+from django_program.registration.purchase_order import PurchaseOrder
+from django_program.registration.services.purchase_orders import create_purchase_order
+from django_program.registration.services.stripe_invoicing import (
+    _get_stripe_client,
+    create_stripe_invoice,
+    handle_invoice_paid_webhook,
+    sync_stripe_invoice_status,
+)
+
+User = get_user_model()
+
+
+# ---------------------------------------------------------------------------
+# Fixtures
+# ---------------------------------------------------------------------------
+
+
+@pytest.fixture
+def conference(db) -> Conference:
+    return Conference.objects.create(
+        name="Stripe Inv Conf",
+        slug="stripe-inv-conf",
+        start_date=date(2027, 7, 1),
+        end_date=date(2027, 7, 3),
+        timezone="UTC",
+        stripe_secret_key="sk_test_fake",
+    )
+
+
+@pytest.fixture
+def staff_user(db) -> User:
+    return User.objects.create_user(username="stripeinvstaff", email="stripeinv@test.com", password="testpass123")
+
+
+@pytest.fixture
+def ticket_type(conference) -> TicketType:
+    return TicketType.objects.create(
+        conference=conference,
+        name="Corporate",
+        slug="corporate-si",
+        price=Decimal("200.00"),
+        total_quantity=0,
+        limit_per_user=10,
+        is_active=True,
+    )
+
+
+@pytest.fixture
+def purchase_order(conference, staff_user, ticket_type) -> PurchaseOrder:
+    return create_purchase_order(
+        conference=conference,
+        organization_name="Stripe Test Org",
+        contact_email="billing@stripe-test.com",
+        contact_name="Stripe Person",
+        billing_address="789 Pay St",
+        line_items=[
+            {
+                "description": "Corporate Ticket",
+                "quantity": 3,
+                "unit_price": Decimal("200.00"),
+                "ticket_type": ticket_type,
+            },
+        ],
+        created_by=staff_user,
+    )
+
+
+def _mock_stripe_client() -> MagicMock:
+    """Build a mock that satisfies the StripeClient -> client chain."""
+    client = MagicMock()
+
+    # customers.list returns empty (create new customer)
+    customer_list = MagicMock()
+    customer_list.data = []
+    client.v1.customers.list.return_value = customer_list
+
+    # customers.create returns an id
+    customer_obj = MagicMock()
+    customer_obj.id = "cus_test_123"
+    client.v1.customers.create.return_value = customer_obj
+
+    # invoices.create returns invoice stub
+    invoice_obj = MagicMock()
+    invoice_obj.id = "in_test_456"
+    client.v1.invoices.create.return_value = invoice_obj
+
+    # invoice_items.create is a no-op
+    client.v1.invoice_items.create.return_value = MagicMock()
+
+    # invoices.finalize_invoice returns finalized invoice
+    finalized = MagicMock()
+    finalized.id = "in_test_456"
+    finalized.hosted_invoice_url = "https://invoice.stripe.com/i/test_hosted"
+    client.v1.invoices.finalize_invoice.return_value = finalized
+
+    # invoices.send_invoice is a no-op
+    client.v1.invoices.send_invoice.return_value = MagicMock()
+
+    return client
+
+
+# ---------------------------------------------------------------------------
+# create_stripe_invoice
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.integration
+@pytest.mark.django_db
+class TestCreateStripeInvoice:
+    def test_create_stripe_invoice(self, purchase_order) -> None:
+        mock_client = _mock_stripe_client()
+        with patch(
+            "django_program.registration.services.stripe_invoicing._get_stripe_client",
+            return_value=mock_client,
+        ):
+            hosted_url = create_stripe_invoice(purchase_order)
+
+        assert hosted_url == "https://invoice.stripe.com/i/test_hosted"
+        purchase_order.refresh_from_db()
+        assert purchase_order.stripe_invoice_id == "in_test_456"
+        assert purchase_order.stripe_invoice_url == "https://invoice.stripe.com/i/test_hosted"
+        mock_client.v1.invoices.finalize_invoice.assert_called_once_with("in_test_456")
+        mock_client.v1.invoices.send_invoice.assert_called_once()
+
+    def test_get_stripe_client_returns_sdk_client(self, conference) -> None:
+        with patch("django_program.registration.services.stripe_invoicing.StripeClient") as mock_sc_cls:
+            mock_instance = MagicMock()
+            mock_instance.client = MagicMock()
+            mock_sc_cls.return_value = mock_instance
+
+            result = _get_stripe_client(conference)
+
+        mock_sc_cls.assert_called_once_with(conference)
+        assert result is mock_instance.client
+
+    def test_create_stripe_invoice_no_key(self, conference, staff_user) -> None:
+        conference.stripe_secret_key = None
+        conference.save(update_fields=["stripe_secret_key"])
+
+        po = create_purchase_order(
+            conference=conference,
+            organization_name="No Key Org",
+            contact_email="nokey@test.com",
+            contact_name="No Key",
+            line_items=[{"description": "Item", "quantity": 1, "unit_price": Decimal("100.00")}],
+            created_by=staff_user,
+        )
+
+        with pytest.raises(ValueError, match=r"[Ss]tripe"):
+            create_stripe_invoice(po)
+
+    def test_create_stripe_invoice_existing_customer(self, purchase_order) -> None:
+        mock_client = _mock_stripe_client()
+        # Override: customer already exists
+        existing_customer = MagicMock()
+        existing_customer.id = "cus_existing"
+        customer_list = MagicMock()
+        customer_list.data = [existing_customer]
+        mock_client.v1.customers.list.return_value = customer_list
+
+        with patch(
+            "django_program.registration.services.stripe_invoicing._get_stripe_client",
+            return_value=mock_client,
+        ):
+            hosted_url = create_stripe_invoice(purchase_order)
+
+        assert hosted_url == "https://invoice.stripe.com/i/test_hosted"
+        mock_client.v1.customers.create.assert_not_called()
+
+    def test_create_stripe_invoice_already_exists(self, purchase_order) -> None:
+        purchase_order.stripe_invoice_id = "in_existing"
+        purchase_order.save(update_fields=["stripe_invoice_id"])
+
+        with pytest.raises(ValueError, match="already has a Stripe invoice"):
+            create_stripe_invoice(purchase_order)
+
+
+# ---------------------------------------------------------------------------
+# sync_stripe_invoice_status
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.integration
+@pytest.mark.django_db
+class TestSyncStripeInvoiceStatus:
+    def test_sync_stripe_invoice_status_paid(self, purchase_order) -> None:
+        purchase_order.stripe_invoice_id = "in_sync_test"
+        purchase_order.save(update_fields=["stripe_invoice_id"])
+
+        mock_client = MagicMock()
+        invoice = MagicMock()
+        # amount_paid in cents: 600.00 USD = 60000 cents
+        invoice.amount_paid = 60000
+        invoice.status = "paid"
+        mock_client.v1.invoices.retrieve.return_value = invoice
+
+        with patch(
+            "django_program.registration.services.stripe_invoicing._get_stripe_client",
+            return_value=mock_client,
+        ):
+            sync_stripe_invoice_status(purchase_order)
+
+        purchase_order.refresh_from_db()
+        assert purchase_order.total_paid == Decimal("600.00")
+        assert purchase_order.status == PurchaseOrder.Status.PAID
+
+    def test_sync_stripe_invoice_no_new_payment(self, purchase_order) -> None:
+        """When Stripe amount_paid matches what's already recorded, no new payment is created."""
+        from django_program.registration.services.purchase_orders import record_payment
+
+        purchase_order.stripe_invoice_id = "in_sync_noop"
+        purchase_order.save(update_fields=["stripe_invoice_id"])
+
+        # Pre-record a payment of 600.00
+        record_payment(
+            purchase_order,
+            amount=Decimal("600.00"),
+            method="stripe",
+            payment_date=date(2027, 7, 1),
+        )
+
+        mock_client = MagicMock()
+        invoice = MagicMock()
+        invoice.amount_paid = 60000  # Same 600.00 already recorded
+        invoice.status = "paid"
+        mock_client.v1.invoices.retrieve.return_value = invoice
+
+        with patch(
+            "django_program.registration.services.stripe_invoicing._get_stripe_client",
+            return_value=mock_client,
+        ):
+            sync_stripe_invoice_status(purchase_order)
+
+        purchase_order.refresh_from_db()
+        # Still 600.00 -- no duplicate payment
+        assert purchase_order.total_paid == Decimal("600.00")
+
+    def test_sync_stripe_invoice_no_invoice_id(self, purchase_order) -> None:
+        with pytest.raises(ValueError, match="no Stripe invoice"):
+            sync_stripe_invoice_status(purchase_order)
+
+
+# ---------------------------------------------------------------------------
+# handle_invoice_paid_webhook
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.integration
+@pytest.mark.django_db
+class TestHandleInvoicePaidWebhook:
+    def test_handle_invoice_paid_webhook(self, purchase_order) -> None:
+        purchase_order.stripe_invoice_id = "in_webhook_test"
+        purchase_order.status = PurchaseOrder.Status.SENT
+        purchase_order.save(update_fields=["stripe_invoice_id", "status"])
+
+        payload = {
+            "data": {
+                "object": {
+                    "id": "in_webhook_test",
+                    "amount_paid": 60000,
+                },
+            },
+        }
+
+        handle_invoice_paid_webhook(payload)
+
+        purchase_order.refresh_from_db()
+        assert purchase_order.total_paid == Decimal("600.00")
+        assert purchase_order.status == PurchaseOrder.Status.PAID
+
+    def test_handle_invoice_paid_webhook_no_matching_po(self) -> None:
+        payload = {
+            "data": {
+                "object": {
+                    "id": "in_nonexistent",
+                    "amount_paid": 10000,
+                },
+            },
+        }
+        # Should not raise -- just logs and returns
+        handle_invoice_paid_webhook(payload)
+
+    def test_handle_invoice_paid_webhook_already_paid(self, purchase_order) -> None:
+        purchase_order.stripe_invoice_id = "in_already_paid"
+        purchase_order.status = PurchaseOrder.Status.PAID
+        purchase_order.save(update_fields=["stripe_invoice_id", "status"])
+
+        payload = {
+            "data": {
+                "object": {
+                    "id": "in_already_paid",
+                    "amount_paid": 60000,
+                },
+            },
+        }
+
+        handle_invoice_paid_webhook(payload)
+
+        purchase_order.refresh_from_db()
+        # No new payment recorded -- still just PAID with 0 total_paid from payments
+        assert purchase_order.status == PurchaseOrder.Status.PAID
+
+    def test_handle_invoice_paid_webhook_no_new_amount(self, purchase_order) -> None:
+        """When payment is already recorded, webhook just updates status without new payment."""
+        from django_program.registration.services.purchase_orders import record_payment
+
+        purchase_order.stripe_invoice_id = "in_already_recorded"
+        purchase_order.status = PurchaseOrder.Status.SENT
+        purchase_order.save(update_fields=["stripe_invoice_id", "status"])
+
+        # Pre-record the full amount
+        record_payment(
+            purchase_order,
+            amount=Decimal("600.00"),
+            method="stripe",
+            payment_date=date(2027, 7, 1),
+        )
+
+        payload = {
+            "data": {
+                "object": {
+                    "id": "in_already_recorded",
+                    "amount_paid": 60000,
+                },
+            },
+        }
+
+        handle_invoice_paid_webhook(payload)
+
+        purchase_order.refresh_from_db()
+        assert purchase_order.total_paid == Decimal("600.00")
+
+    def test_handle_invoice_paid_webhook_zero_new_amount(self, conference, staff_user, ticket_type) -> None:
+        """When amount_paid matches what's already recorded, update_po_status is called but no new payment."""
+        from django_program.registration.services.purchase_orders import record_payment
+
+        # Create a PO with a large total so partial payment doesn't set status to PAID
+        po = create_purchase_order(
+            conference=conference,
+            organization_name="Zero New Org",
+            contact_email="zero@test.com",
+            contact_name="Zero",
+            line_items=[
+                {
+                    "description": "Big Ticket",
+                    "quantity": 10,
+                    "unit_price": Decimal("200.00"),
+                    "ticket_type": ticket_type,
+                },
+            ],
+            created_by=staff_user,
+        )
+        po.stripe_invoice_id = "in_zero_new"
+        po.status = PurchaseOrder.Status.SENT
+        po.save(update_fields=["stripe_invoice_id", "status"])
+
+        # Pre-record a partial payment of 100.00
+        record_payment(
+            po,
+            amount=Decimal("100.00"),
+            method="stripe",
+            payment_date=date(2027, 7, 1),
+        )
+        po.refresh_from_db()
+        assert po.status == PurchaseOrder.Status.PARTIALLY_PAID
+
+        # Webhook reports same 100.00 (10000 cents) -- no new amount
+        payload = {
+            "data": {
+                "object": {
+                    "id": "in_zero_new",
+                    "amount_paid": 10000,
+                },
+            },
+        }
+
+        handle_invoice_paid_webhook(payload)
+
+        po.refresh_from_db()
+        assert po.total_paid == Decimal("100.00")
+
+    def test_handle_invoice_paid_webhook_empty_id(self) -> None:
+        payload = {"data": {"object": {"amount_paid": 1000}}}
+        handle_invoice_paid_webhook(payload)
+
+    def test_handle_invoice_paid_webhook_bad_payload(self) -> None:
+        handle_invoice_paid_webhook({"data": "not_a_dict"})
+        handle_invoice_paid_webhook({})
+        handle_invoice_paid_webhook({"data": {"object": "not_a_dict"}})