diff --git a/.changeset/13075-nav-visible-envelope.md b/.changeset/13075-nav-visible-envelope.md
new file mode 100644
index 0000000000..abf8ccad57
--- /dev/null
+++ b/.changeset/13075-nav-visible-envelope.md
@@ -0,0 +1,20 @@
+---
+'@object-ui/types': minor
+'@object-ui/layout': minor
+'@object-ui/app-shell': patch
+---
+
+A navigation item's `visible` now takes `@objectstack/spec`'s `EvaluatedExpressionInputSchema` by reference, beside the boolean it already took (objectui#13075).
+
+The spec types every navigation entry's `visible` as an evaluated expression input: a non-blank CEL string, or the `{ dialect, source }` envelope the spec's own parse produces. objectui's `NavigationItemSchema` typed it as `boolean | string`, so the two disagreed both ways. This changes what `NavigationItemSchema` (and so `objectui validate`) accepts:
+
+- **Widened: the envelope is accepted.** `visible: { dialect: 'cel', source: "'org_admin' in current_user.positions" }` used to be refused. It parses now and is kept as written. The TypeScript type `NavigationItem['visible']` is `boolean | EvaluatedExpressionInput` (the spec's input type), so a typed literal can carry the envelope too.
+- **Narrowed (breaking): a blank string is refused.** `visible: ''` and a whitespace-only string used to pass. They are refused now with the spec's own code (`invalid_union` at `visible`) and sentence. A blank `source` inside an envelope is refused at `visible.source`, as the spec refuses it. To show an entry to everyone, omit `visible`.
+
+Unchanged: a non-blank string is still accepted and kept as a string (the validator does not rewrite it into an envelope), and `visible: true` / `false` are still accepted. The boolean is the one stated divergence from the spec on this key.
+
+Code that reads `NavigationItem['visible']` and passes it on as `string | boolean` no longer compiles: widen that parameter to `NavigationItem['visible']`.
+
+`@object-ui/layout` (minor): the exported `VisibilityEvaluator` type now takes `NavigationItem['visible']` instead of `string | boolean | undefined`, so an evaluator receives the envelope as authored. An evaluator a host passes in whose parameter is the old, narrower type no longer type-checks; widen it the same way. The runtime is unchanged: `NavigationRenderer` already handed the value through.
+
+`@object-ui/app-shell` (patch): the shell's navigation gates (`useNavMemberGates` and the `nav:menu` block) take the widened type internally. No exported type changes, and the runtime is unchanged: `evaluateNavigationVisibility` already evaluated the envelope.
diff --git a/packages/app-shell/src/hooks/useNavMemberGates.ts b/packages/app-shell/src/hooks/useNavMemberGates.ts
index 1a15dafef1..8040a714fc 100644
--- a/packages/app-shell/src/hooks/useNavMemberGates.ts
+++ b/packages/app-shell/src/hooks/useNavMemberGates.ts
@@ -106,7 +106,7 @@ export interface NavMemberGates {
 export function useNavMemberGates(): NavMemberGates {
   const { evaluator, app } = useExpressionContext();
   const evalVis = useCallback(
-    (expr: string | boolean | undefined) => evaluateNavigationVisibility(expr, evaluator),
+    (expr: NavigationItem['visible']) => evaluateNavigationVisibility(expr, evaluator),
     [evaluator],
   );
 
diff --git a/packages/app-shell/src/layout/__tests__/navItemVisibleEvaluated.test.tsx b/packages/app-shell/src/layout/__tests__/navItemVisibleEvaluated.test.tsx
index 2e8ea70f01..09dec6a0f8 100644
--- a/packages/app-shell/src/layout/__tests__/navItemVisibleEvaluated.test.tsx
+++ b/packages/app-shell/src/layout/__tests__/navItemVisibleEvaluated.test.tsx
@@ -81,7 +81,7 @@ const OUTSIDER = { id: 'u_outsider', name: 'Otto', email: 'otto@example.com', po
 function NavUnderProvider({ items, enablePinning }: { items: NavigationItem[]; enablePinning?: boolean }) {
   const { evaluator } = useExpressionContext();
   const evalVis = React.useCallback(
-    (expr: string | boolean | undefined) => evaluateVisibility(expr, evaluator),
+    (expr: NavigationItem['visible']) => evaluateVisibility(expr, evaluator),
     [evaluator],
   );
   return (
@@ -276,7 +276,7 @@ describe('nav item `visible` is evaluated per item by the shell (objectui#10119)
         children: [{ id: 'nav_secret', type: 'object', objectName: 'demo_thing', label: 'Secret', visible: false }],
       },
     ];
-    const literal = (expr: string | boolean | undefined) => expr !== false && expr !== 'false';
+    const literal = (expr: NavigationItem['visible']) => expr !== false && expr !== 'false';
 
     expect(hasVisibleNavigationItems(hiddenAncestor, { evaluateVisibility: literal })).toBe(false);
     expect(hasVisibleNavigationItems(allChildrenHidden, { evaluateVisibility: literal })).toBe(false);
diff --git a/packages/app-shell/src/views/nav-menu-renderer.tsx b/packages/app-shell/src/views/nav-menu-renderer.tsx
index 086c1e1450..88ee6b899d 100644
--- a/packages/app-shell/src/views/nav-menu-renderer.tsx
+++ b/packages/app-shell/src/views/nav-menu-renderer.tsx
@@ -185,7 +185,7 @@ export const NavMenuRenderer: React.FC<NavMenuRendererProps> = ({
 
   const { evaluator } = useExpressionContext();
   const evalVis = useCallback(
-    (expr: string | boolean | undefined) => evaluateNavigationVisibility(expr, evaluator),
+    (expr: NavigationItem['visible']) => evaluateNavigationVisibility(expr, evaluator),
     [evaluator],
   );
 
diff --git a/packages/layout/src/NavigationRenderer.tsx b/packages/layout/src/NavigationRenderer.tsx
index c268da2c38..6dc9a2c1b0 100644
--- a/packages/layout/src/NavigationRenderer.tsx
+++ b/packages/layout/src/NavigationRenderer.tsx
@@ -137,9 +137,13 @@ const HIDDEN_ICON_LABEL_NOT_FOCUSABLE =
  * Callback to evaluate a visibility expression.
  * Return `true` if the item should be visible.
  * When not provided, all items default to visible.
+ *
+ * The parameter is the item's own `visible` type, so the spec's
+ * `{ dialect, source }` envelope reaches the evaluator as authored
+ * (objectui#13075).
  */
 export type VisibilityEvaluator = (
-  expression: string | boolean | undefined,
+  expression: NavigationItem['visible'],
 ) => boolean;
 
 /**
diff --git a/packages/types/src/__tests__/navigation-spec-parity.test.ts b/packages/types/src/__tests__/navigation-spec-parity.test.ts
index 27f3d49a2b..c4c7986ccc 100644
--- a/packages/types/src/__tests__/navigation-spec-parity.test.ts
+++ b/packages/types/src/__tests__/navigation-spec-parity.test.ts
@@ -194,6 +194,78 @@ describe('referencing the spec NavigationItemSchema would reject metadata object
 });
 
 
+// ─────────────────────────────────────────────────────────────────────────────
+// `visible`: the spec's expression input, both ways (objectui#13075)
+// ─────────────────────────────────────────────────────────────────────────────
+
+/**
+ * The spec types every nav branch's `visible` as `EvaluatedExpressionInputSchema`:
+ * a non-blank predicate string, or the `{ dialect, source }` envelope its own
+ * parse produces. The mirror's slot was `boolean | string`, so it refused the
+ * envelope and accepted a blank string — a divergence both ways that no row
+ * above recorded. The mirror now takes the spec's schema by reference beside
+ * its boolean arm, so the boolean (the `visible: boolean` row above) is the one
+ * divergence left on this key.
+ *
+ * Each verdict is read off BOTH schemas, on an ordinary entry and on a `doc`
+ * entry (which the spec's `doc` arm judges), so an agreement cannot pass
+ * because one side refuses everything.
+ */
+describe('objectui#13075 — `visible` takes the spec\'s expression input', () => {
+  const ENTRIES: Array<[string, Record<string, unknown>]> = [
+    ['a url entry', { id: 'nav_ai', type: 'url', label: 'AI', url: '/ai' }],
+    ['a doc entry', { id: 'nav_help', type: 'doc', book: 'crm_manual' }],
+  ];
+  /** An envelope that reads no `data`, so the spec's data-source rule does not apply. */
+  const ENVELOPE = { dialect: 'cel', source: "'org_admin' in current_user.positions" };
+
+  it.each(ENTRIES)('the `{ dialect, source }` envelope parses on both (%s), and the mirror keeps it as written', (_name, entry) => {
+    const input = { ...entry, visible: ENVELOPE };
+    expect(SpecNavigationItemSchema.safeParse(input).success).toBe(true);
+    expect(keep(input)).toEqual(input);
+  });
+
+  it.each(ENTRIES.flatMap(([name, entry]) => [
+    [name, '\'\'', { ...entry, visible: '' }],
+    [name, 'whitespace', { ...entry, visible: '   ' }],
+  ] as Array<[string, string, Record<string, unknown>]>))(
+    'a blank string is refused by both (%s, %s), with the spec\'s code and sentence',
+    (_name, _blank, input) => {
+      const spec = SpecNavigationItemSchema.safeParse(input);
+      const mirror = NavigationItemSchema.safeParse(input);
+      expect(refusal(spec)).toEqual(['invalid_union @ visible']);
+      expect(refusal(mirror)).toEqual(['invalid_union @ visible']);
+      expect(!mirror.success && mirror.error.issues[0].message).toBe(!spec.success && spec.error.issues[0].message);
+    },
+  );
+
+  it('a blank `source` inside the envelope is refused by both, once, at `source`', () => {
+    const input = { id: 'nav_ai', type: 'url', label: 'AI', url: '/ai', visible: { dialect: 'cel', source: ' ' } };
+    expect(refusal(SpecNavigationItemSchema.safeParse(input))).toEqual(['custom @ visible.source']);
+    expect(refusal(NavigationItemSchema.safeParse(input))).toEqual(['custom @ visible.source']);
+  });
+
+  it('CONTROL — a bare non-blank string parses on both, and the mirror does not rewrite it into an envelope', () => {
+    const input = { id: 'nav_ai', type: 'url', label: 'AI', url: '/ai', visible: "'org_admin' in current_user.positions" };
+    expect(SpecNavigationItemSchema.safeParse(input).success).toBe(true);
+    expect(keep(input)).toEqual(input);
+  });
+
+  it('CONTROL — a boolean still parses on the mirror and stays the one divergence (the `visible: boolean` row)', () => {
+    for (const visible of [true, false]) {
+      const input = { id: 'nav_ai', type: 'url', label: 'AI', url: '/ai', visible };
+      expect(keep(input)).toEqual(input);
+      expect(SpecNavigationItemSchema.safeParse(input).success).toBe(false);
+    }
+  });
+
+  it('the TypeScript face admits the envelope (compile-time)', () => {
+    const entry: NavigationItem = { id: 'nav_ai', type: 'url', label: 'AI', url: '/ai', visible: { dialect: 'cel', source: 'true' } };
+    expect(keep(entry)).toEqual(entry);
+  });
+});
+
+
 // ─────────────────────────────────────────────────────────────────────────────
 // The type vocabulary and the `doc` entry (objectui#11197)
 // ─────────────────────────────────────────────────────────────────────────────
diff --git a/packages/types/src/app.ts b/packages/types/src/app.ts
index c55466fcca..bfef32fb0c 100644
--- a/packages/types/src/app.ts
+++ b/packages/types/src/app.ts
@@ -58,6 +58,7 @@ import type {
   DocNavItem as SpecDocNavItem,
   App as SpecApp,
 } from '@objectstack/spec/ui';
+import type { EvaluatedExpressionInput } from '@objectstack/spec/shared';
 import type { BaseSchema } from './base.js';
 import type { z } from 'zod';
 import type { APP_SPEC_EXCLUDED, AppContextSelectorSchema } from './zod/app.zod.js';
@@ -276,16 +277,22 @@ export interface NavigationEntryItem {
   // -- Visibility & Permissions --
 
   /**
-   * Visibility expression — boolean or expression string e.g. "${user.role === 'admin'}".
+   * Visibility predicate — a CEL string, the spec's `{ dialect, source }`
+   * envelope, or a boolean.
    *
-   * NOT derived (#3177): the spec takes a CEL string on input and an Expression
-   * envelope `{ dialect, source }` on output — `boolean` is absent at BOTH
-   * tiers. `NavigationRenderer`'s `evalVis(item.visible)` honours the boolean,
+   * The expression half is the spec's input type, `EvaluatedExpressionInput`,
+   * by reference (objectui#13075) — the same type the zod twin
+   * (`NavigationItemSchema`) takes by reference. Until then this was
+   * `boolean | string`, which left out the envelope the spec's own parse
+   * produces.
+   *
+   * The `boolean` arm is NOT derived (#3177): the spec admits it at neither
+   * tier. `NavigationRenderer`'s `evalVis(item.visible)` honours the boolean,
    * and `menuItemToNavigationItem` produces one when mapping legacy
    * `AppMenuItem.hidden`. Pinned in `spec-derived-unions.test.ts`, which fails the
    * day the spec accepts a boolean and this can come off it.
    */
-  visible?: boolean | string;
+  visible?: boolean | EvaluatedExpressionInput;
 
   /** Required permissions to see/access this item */
   requiredPermissions?: string[];
diff --git a/packages/types/src/zod/app.zod.ts b/packages/types/src/zod/app.zod.ts
index a8df21a2b8..9e64d7e864 100644
--- a/packages/types/src/zod/app.zod.ts
+++ b/packages/types/src/zod/app.zod.ts
@@ -31,6 +31,10 @@ import {
   // to this paragraph.
   objectNavTargetExclusivity,
 } from '@objectstack/spec/ui';
+import {
+  EvaluatedExpressionInputSchema as SpecEvaluatedExpressionInputSchema,
+  EvaluatedExpressionSchema as SpecEvaluatedExpressionSchema,
+} from '@objectstack/spec/shared';
 import { BaseSchema, specFieldsExcept } from './base.zod.js';
 import { aliasKeyRefusal, retirementTombstone } from './tombstone.zod.js';
 import type { AppMenuItem, NavigationItemType } from '../app.js';
@@ -196,6 +200,49 @@ function refuseEmptyNavLabel(item: { type: string; label?: unknown }, ctx: z.Ref
   });
 }
 
+/**
+ * A navigation entry's `visible`: the spec's `EvaluatedExpressionInputSchema`,
+ * by reference, beside the one pinned objectui arm, `boolean` (objectui#13075).
+ *
+ * The spec types every nav branch's `visible` as `EvaluatedExpressionInputSchema`:
+ * a non-blank predicate string, or the `{ dialect, source }` envelope its own
+ * parse produces (`defineApp` returns the parsed app, so a string authored there
+ * comes back as the envelope). Until objectui#13075 this slot was
+ * `boolean | string`: it refused the envelope the spec accepts, and accepted a
+ * blank string the spec refuses. Both are the spec's verdicts now.
+ *
+ * Spelled the way `visibleWhen`'s wire is in `./base.zod.ts`, and for the same
+ * reason: the accept set is the spec's input type (a string, or the spec's own
+ * `EvaluatedExpressionSchema` read by reference), and every verdict on a
+ * non-boolean value is the spec's — the value is handed to
+ * `EvaluatedExpressionInputSchema` and its issues are the refusal, so a blank
+ * string is refused with the spec's code and sentence. The judge runs only on a
+ * value an arm already took, so one fault is never reported twice. What is NOT taken is the
+ * spec's transform, which rewrites a bare string into `{ dialect: 'cel', source }`:
+ * this mirror writes nothing into an author's document (decision batches #69 /
+ * #90), so a string stays a string.
+ *
+ * `boolean` is the stated divergence: the spec admits it at neither tier, and
+ * `menuItemToNavigationItem` manufactures one when it inverts legacy
+ * `AppMenuItem.hidden`. `../__tests__/navigation-spec-parity.test.ts` pins all
+ * three rows: the envelope and the blank string agree with the spec, the boolean
+ * does not.
+ */
+function specVisibleRefusal(visible: unknown): z.core.$ZodIssue[] {
+  const verdict = stripImportedDefaults(SpecEvaluatedExpressionInputSchema).safeParse(visible);
+  return verdict.success ? [] : verdict.error.issues;
+}
+const NavigationVisibleSchema = z
+  .union([z.boolean(), z.string(), stripImportedDefaults(SpecEvaluatedExpressionSchema)], {
+    // A value no arm takes (`{ dialect: 'cel' }`, a number) is refused with the
+    // spec's own sentence for it, not zod's generic one.
+    error: (issue) => specVisibleRefusal(issue.input)[0]?.message,
+  })
+  .superRefine((visible, ctx) => {
+    if (typeof visible === 'boolean') return;
+    for (const issue of specVisibleRefusal(visible)) ctx.addIssue({ ...issue, message: issue.message });
+  }, { when: (payload) => payload.issues.length === 0 });
+
 /** `a`, `b` and `c` — the separator refusal's list of what a separator may carry. */
 function codeList(keys: readonly string[]): string {
   const quoted = keys.map((key) => `\`${key}\``);
@@ -253,7 +300,7 @@ const NavigationItemObject = z.object({
   }).optional().describe('Action payload (type: action)'),
 
   // Visibility & Permissions
-  visible: z.union([z.boolean(), z.string()]).optional().describe('Visibility expression'),
+  visible: NavigationVisibleSchema.optional().describe("Visibility predicate: a non-blank CEL string or the spec's `{ dialect, source }` envelope (`@objectstack/spec` `EvaluatedExpressionInputSchema`), or a boolean"),
   // objectui#12971: the spec's shared nav-item base declares one API data source
   // (objectstack#24332, `ElementApiDataSourceSchema` by reference), whose bound
   // value an entry's `visible` reads as `data`. Taken by reference for the
@@ -435,7 +482,10 @@ export const NavigationItemSchema: z.ZodType<any> = z.lazy(() => NavigationItemA
  *    against spec 17.2.0, referencing the spec's schema would make `objectui
  *    validate` REJECT metadata this renderer accepts today: `pinned` and
  *    `defaultOpen` fail `unrecognized_keys`, `visible: boolean` fails
- *    `invalid_union`, and a one-character `id` fails `too_small`. Pinned by
+ *    `invalid_union`, and a one-character `id` fails `too_small`. (`visible`'s
+ *    other arms are the spec's own `EvaluatedExpressionInputSchema` since
+ *    objectui#13075, so its envelope and its blank-string refusal agree; only
+ *    the boolean parts.) Pinned by
  *    `__tests__/navigation-spec-parity.test.ts`. (A separator carrying `label`
  *    was a fifth until objectui#10867, which made the mirror refuse it too.)
  *