diff --git a/packages/app-shell/src/views/metadata-admin/anchors.ts b/packages/app-shell/src/views/metadata-admin/anchors.ts
index fabc480ff..db5e1ade9 100644
--- a/packages/app-shell/src/views/metadata-admin/anchors.ts
+++ b/packages/app-shell/src/views/metadata-admin/anchors.ts
@@ -186,7 +186,7 @@ export function registerBuiltinAnchors(): void {
     },
   });
 
-  // flow / workflow may reference an object at the root or under `on`
+  // flow may reference an object at the root or under `on`
   registerMetadataResource({
     type: 'flow',
     anchors: [{
@@ -201,16 +201,8 @@ export function registerBuiltinAnchors(): void {
     ],
     createDefaults: { nodes: [], edges: [] },
   });
-  registerMetadataResource({
-    type: 'workflow',
-    anchors: [{
-      anchorType: 'object',
-      match: anchorByField(['object', 'on.object']),
-      groupLabel: 'Workflow Rules',
-      order: 51,
-    }],
-    createFields: ['name', 'objectName', 'triggerType', 'description'],
-  });
+  // ADR-0020: `workflow` retired as a metadata type — record state machines
+  // are a `state_machine` validation rule on the object (no separate anchor).
 
   // trigger.object → object (low-level DB-style triggers)
   registerMetadataResource({
diff --git a/packages/app-shell/src/views/metadata-admin/clientValidation.ts b/packages/app-shell/src/views/metadata-admin/clientValidation.ts
index 58dd9d503..79e079759 100644
--- a/packages/app-shell/src/views/metadata-admin/clientValidation.ts
+++ b/packages/app-shell/src/views/metadata-admin/clientValidation.ts
@@ -64,7 +64,9 @@ const LOADERS: Record<string, SchemaLoader> = {
 
   // automation
   flow: async () => (await import('@objectstack/spec/automation')).FlowSchema as unknown as ZodLikeSchema,
-  workflow: async () => (await import('@objectstack/spec/automation')).StateMachineSchema as unknown as ZodLikeSchema,
+  // `workflow` is no longer a standalone metadata type (ADR-0020) — record
+  // state machines are a `state_machine` validation rule on the object,
+  // validated as part of ObjectSchema; there is no top-level workflow schema.
   // `approval` is no longer a standalone metadata type — it's a flow node
   // (`type: 'approval'`, ADR-0019). Its config (ApprovalNodeConfigSchema) is
   // validated as part of the enclosing flow; there is no top-level schema, so
diff --git a/packages/app-shell/src/views/metadata-admin/i18n.ts b/packages/app-shell/src/views/metadata-admin/i18n.ts
index 5b4f0371e..1e5ec868d 100644
--- a/packages/app-shell/src/views/metadata-admin/i18n.ts
+++ b/packages/app-shell/src/views/metadata-admin/i18n.ts
@@ -40,7 +40,7 @@ const TYPE_LABELS_EN: Record<string, string> = {
   report: 'Report',
   // Automation
   flow: 'Flow',
-  workflow: 'Workflow',
+  // ADR-0020: `workflow` retired as a metadata type.
   approval: 'Approval Process',
   // System
   datasource: 'Datasource',
@@ -86,7 +86,7 @@ const TYPE_LABELS_ZH: Record<string, string> = {
   action: '操作',
   report: '报表',
   flow: '流程',
-  workflow: '工作流',
+  // ADR-0020: `workflow` 已不再是独立元数据类型。
   approval: '审批流程',
   datasource: '数据源',
   translation: '翻译',
diff --git a/packages/app-shell/src/views/metadata-admin/inspectors/WorkflowActionInspector.tsx b/packages/app-shell/src/views/metadata-admin/inspectors/WorkflowActionInspector.tsx
deleted file mode 100644
index 891074466..000000000
--- a/packages/app-shell/src/views/metadata-admin/inspectors/WorkflowActionInspector.tsx
+++ /dev/null
@@ -1,166 +0,0 @@
-// Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
-
-/**
- * WorkflowActionInspector — scoped editor for the selected workflow
- * action (immediate or time-dependent).
- *
- * Selection shapes:
- *   { kind: 'action', id: 'actions[i]' }                      — immediate
- *   { kind: 'action', id: 'timeTriggers[i].actions[j]' }     — scheduled
- *
- * Patches: rewrite the appropriate slot in the draft, then onPatch().
- */
-
-import * as React from 'react';
-import type { MetadataInspectorProps } from '../inspector-registry';
-import { t } from '../i18n';
-import {
-  InspectorShell,
-  InspectorReorderButtons,
-  InspectorTextField,
-  InspectorSelectField,
-  InspectorRemoveButton,
-  InspectorEmptyState,
-  spliceArray,
-  moveArray,
-} from './_shared';
-
-interface WorkflowAction { type?: string; name?: string; [k: string]: unknown }
-interface TimeTrigger { offset?: number; unit?: string; actions?: WorkflowAction[]; [k: string]: unknown }
-
-const ACTION_TYPES = [
-  'field_update', 'email_alert', 'task_create', 'outbound_message',
-  'webhook', 'apex', 'flow_invoke', 'notification',
-];
-
-interface ParsedSel {
-  scope: 'immediate' | 'timed';
-  i: number;
-  j?: number;
-}
-
-function parseSelectionId(id: string): ParsedSel | null {
-  const a = /^actions\[(\d+)\]$/.exec(id);
-  if (a) return { scope: 'immediate', i: Number(a[1]) };
-  const b = /^timeTriggers\[(\d+)\]\.actions\[(\d+)\]$/.exec(id);
-  if (b) return { scope: 'timed', i: Number(b[1]), j: Number(b[2]) };
-  return null;
-}
-
-export function WorkflowActionInspector({ selection, draft, onPatch, onClearSelection, onSelectionChange, locale, readOnly }: MetadataInspectorProps) {
-  const parsed = parseSelectionId(selection.id);
-  const immediate = Array.isArray((draft as any).actions) ? (draft as any).actions as WorkflowAction[] : [];
-  const timed = Array.isArray((draft as any).timeTriggers) ? (draft as any).timeTriggers as TimeTrigger[] : [];
-
-  const action: WorkflowAction | null = (() => {
-    if (!parsed) return null;
-    if (parsed.scope === 'immediate') return immediate[parsed.i] ?? null;
-    const t = timed[parsed.i];
-    if (!t || !Array.isArray(t.actions)) return null;
-    return t.actions[parsed.j!] ?? null;
-  })();
-
-  if (!action || !parsed) {
-    return (
-      <InspectorShell kindLabel={t('engine.inspector.workflowAction.kind', locale)} title={selection.label ?? selection.id} onClose={onClearSelection} closeLabel={t('engine.inspector.workflowAction.close', locale)}>
-        <InspectorEmptyState message={selection.id} />
-      </InspectorShell>
-    );
-  }
-
-  const patch = (updates: Partial<WorkflowAction>) => {
-    const next = { ...action, ...updates };
-    if (parsed.scope === 'immediate') {
-      onPatch({ actions: spliceArray(immediate, parsed.i, next) });
-    } else {
-      const trig = timed[parsed.i];
-      const newActions = spliceArray(trig.actions ?? [], parsed.j!, next);
-      const newTrigs = spliceArray(timed, parsed.i, { ...trig, actions: newActions });
-      onPatch({ timeTriggers: newTrigs });
-    }
-  };
-
-  const remove = () => {
-    if (parsed.scope === 'immediate') {
-      onPatch({ actions: spliceArray(immediate, parsed.i, null) });
-    } else {
-      const trig = timed[parsed.i];
-      const newActions = spliceArray(trig.actions ?? [], parsed.j!, null);
-      onPatch({ timeTriggers: spliceArray(timed, parsed.i, { ...trig, actions: newActions }) });
-    }
-    onClearSelection();
-  };
-
-  const otherConfig = React.useMemo(() => {
-    const { type, name, ...rest } = action;
-    return JSON.stringify(rest, null, 2);
-  }, [action]);
-  const [configText, setConfigText] = React.useState(otherConfig);
-  const [configError, setConfigError] = React.useState<string | null>(null);
-  React.useEffect(() => { setConfigText(otherConfig); setConfigError(null); }, [otherConfig]);
-
-  const commitConfig = () => {
-    try {
-      const parsedObj = configText.trim() === '' ? {} : JSON.parse(configText);
-      if (!parsedObj || typeof parsedObj !== 'object' || Array.isArray(parsedObj)) throw new Error('not object');
-      setConfigError(null);
-      patch(parsedObj as Partial<WorkflowAction>);
-    } catch (e) {
-      setConfigError(String((e as Error).message));
-    }
-  };
-
-  const { currentIndex, total } = (() => {
-    if (parsed.scope === 'immediate') return { currentIndex: parsed.i, total: immediate.length };
-    const trig = timed[parsed.i];
-    const arr = Array.isArray(trig?.actions) ? trig.actions : [];
-    return { currentIndex: parsed.j!, total: arr.length };
-  })();
-
-  const move = (to: number) => {
-    if (parsed.scope === 'immediate') {
-      onPatch({ actions: moveArray(immediate, parsed.i, to) });
-      onSelectionChange?.({ kind: 'action', id: `actions[${to}]`, label: action.name || action.type });
-    } else {
-      const trig = timed[parsed.i];
-      const newActions = moveArray(trig.actions ?? [], parsed.j!, to);
-      onPatch({ timeTriggers: spliceArray(timed, parsed.i, { ...trig, actions: newActions }) });
-      onSelectionChange?.({ kind: 'action', id: `timeTriggers[${parsed.i}].actions[${to}]`, label: action.name || action.type });
-    }
-  };
-
-  return (
-    <InspectorShell
-      kindLabel={t('engine.inspector.workflowAction.kind', locale)}
-      title={action.name || action.type || selection.id}
-      onClose={onClearSelection}
-      closeLabel={t('engine.inspector.workflowAction.close', locale)}
-      headerActions={
-        <InspectorReorderButtons
-          index={currentIndex}
-          total={total}
-          onMove={move}
-          upLabel={t('engine.inspector.reorder.up', locale)}
-          downLabel={t('engine.inspector.reorder.down', locale)}
-          disabled={readOnly}
-        />
-      }
-      footer={<InspectorRemoveButton label={t('engine.inspector.workflowAction.remove', locale)} onClick={remove} disabled={readOnly} />}
-    >
-      <InspectorSelectField label={t('engine.inspector.workflowAction.type', locale)} value={action.type} options={ACTION_TYPES.map((v) => ({ value: v, label: v }))} onCommit={(v) => patch({ type: v })} disabled={readOnly} />
-      <InspectorTextField label={t('engine.inspector.workflowAction.name', locale)} value={action.name ?? ''} onCommit={(v) => patch({ name: v })} disabled={readOnly} />
-      <div className="space-y-1">
-        <label className="text-xs text-muted-foreground">{t('engine.inspector.workflowAction.config', locale)}</label>
-        <textarea
-          value={configText}
-          onChange={(e) => setConfigText(e.target.value)}
-          onBlur={commitConfig}
-          disabled={readOnly}
-          rows={8}
-          className="w-full rounded border px-2 py-1.5 text-xs font-mono bg-background"
-        />
-        {configError && <div className="text-xs text-destructive">{configError}</div>}
-      </div>
-    </InspectorShell>
-  );
-}
diff --git a/packages/app-shell/src/views/metadata-admin/inspectors/index.ts b/packages/app-shell/src/views/metadata-admin/inspectors/index.ts
index abf650d61..26556b285 100644
--- a/packages/app-shell/src/views/metadata-admin/inspectors/index.ts
+++ b/packages/app-shell/src/views/metadata-admin/inspectors/index.ts
@@ -9,7 +9,6 @@ import { registerMetadataInspector } from '../inspector-registry';
 import { registerMetadataDefaultInspector } from '../default-inspector-registry';
 import { DashboardWidgetInspector } from './DashboardWidgetInspector';
 import { FlowInspector } from './FlowInspector';
-import { WorkflowActionInspector } from './WorkflowActionInspector';
 import { AppNavInspector } from './AppNavInspector';
 import { ViewInspector, ViewDefaultInspector } from './ViewInspector';
 import { PageBlockInspector } from './PageBlockInspector';
@@ -22,7 +21,9 @@ export function registerBuiltinInspectors(): void {
   // edited through FlowInspector, not a standalone step inspector. FlowInspector
   // routes node vs. edge selections to the right scoped editor.
   registerMetadataInspector('flow', FlowInspector);
-  registerMetadataInspector('workflow', WorkflowActionInspector);
+  // ADR-0020: `workflow` retired as a metadata type — no workflow-action
+  // inspector. State machines live on the object as a `state_machine`
+  // validation rule.
   registerMetadataInspector('app', AppNavInspector);
   registerMetadataInspector('view', ViewInspector);
   registerMetadataDefaultInspector('view', ViewDefaultInspector);
diff --git a/packages/app-shell/src/views/metadata-admin/previews/ValidationPreview.tsx b/packages/app-shell/src/views/metadata-admin/previews/ValidationPreview.tsx
index 01baa2c7a..6d3dca95b 100644
--- a/packages/app-shell/src/views/metadata-admin/previews/ValidationPreview.tsx
+++ b/packages/app-shell/src/views/metadata-admin/previews/ValidationPreview.tsx
@@ -206,23 +206,26 @@ function TypeBody({ type, d }: { type: string; d: Record<string, unknown> }) {
     }
 
     case 'state_machine': {
-      const transitions = Array.isArray(d.transitions)
-        ? (d.transitions as Array<{ from?: string | string[]; to?: string }>)
-        : [];
+      // ADR-0020 shape: transitions is a `{ fromState: [allowedToStates] }` map.
+      const transitionMap =
+        d.transitions && typeof d.transitions === 'object' && !Array.isArray(d.transitions)
+          ? (d.transitions as Record<string, string[]>)
+          : {};
+      const entries = Object.entries(transitionMap);
       const field = d.field as string | undefined;
       return (
         <Section title={`Transitions${field ? ` on ${field}` : ''}`} icon={Workflow}>
-          {transitions.length === 0 ? (
+          {entries.length === 0 ? (
             <div className="text-xs text-amber-700 dark:text-amber-400">No transitions declared.</div>
           ) : (
             <ul className="rounded border bg-background divide-y text-xs">
-              {transitions.map((t, i) => (
-                <li key={i} className="flex items-center gap-2 px-2.5 py-1.5">
-                  <span className="font-mono">
-                    {Array.isArray(t.from) ? t.from.join(' | ') : (t.from ?? '*')}
-                  </span>
+              {entries.map(([from, tos]) => (
+                <li key={from} className="flex items-center gap-2 px-2.5 py-1.5">
+                  <span className="font-mono">{from}</span>
                   <ArrowRight className="h-3 w-3 text-muted-foreground" />
-                  <span className="font-mono text-emerald-700 dark:text-emerald-400">{t.to ?? '?'}</span>
+                  <span className="font-mono text-emerald-700 dark:text-emerald-400">
+                    {Array.isArray(tos) && tos.length > 0 ? tos.join(' | ') : '∅ (dead-end)'}
+                  </span>
                 </li>
               ))}
             </ul>
diff --git a/packages/app-shell/src/views/metadata-admin/previews/WorkflowPreview.tsx b/packages/app-shell/src/views/metadata-admin/previews/WorkflowPreview.tsx
deleted file mode 100644
index 329917cc8..000000000
--- a/packages/app-shell/src/views/metadata-admin/previews/WorkflowPreview.tsx
+++ /dev/null
@@ -1,399 +0,0 @@
-// Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
-
-/**
- * WorkflowPreview — read-only summary of a Workflow Rule metadata
- * draft (Salesforce-style declarative workflow: trigger + criteria +
- * immediate actions + time-dependent actions).
- *
- * Renders three sections side-by-side:
- *   1. Trigger envelope: object, trigger type, criteria CEL.
- *   2. Immediate actions: one row per action with type-specific summary.
- *   3. Time-dependent actions: scheduled offsets relative to trigger.
- *
- * Workflow schema isn't a state machine — it is a "when X then do Y"
- * rule. We render it as such instead of forcing a DAG metaphor onto it.
- */
-
-import * as React from 'react';
-import {
-  AlarmClock,
-  ArrowRight,
-  Bell,
-  Bot,
-  Code2,
-  Filter,
-  Globe,
-  ListChecks,
-  Mail,
-  Pencil,
-  Plug,
-  Plus,
-  PlayCircle,
-  Power,
-  Workflow as WorkflowIcon,
-} from 'lucide-react';
-import { cn } from '@object-ui/components';
-import type { MetadataPreviewProps } from '../preview-registry';
-import { PreviewShell, PreviewMessage, PreviewErrorBoundary } from './PreviewShell';
-import { appendArray } from '../inspectors/_shared';
-import { t as tr } from '../i18n';
-
-interface WorkflowAction {
-  type: string;
-  [key: string]: unknown;
-}
-
-interface TimeTrigger {
-  offset?: number;
-  unit?: string;
-  baseField?: string;
-  baseEvent?: string;
-  actions?: WorkflowAction[];
-  [key: string]: unknown;
-}
-
-function actionIcon(type: string) {
-  switch (type) {
-    case 'field_update':
-      return Pencil;
-    case 'email_alert':
-      return Mail;
-    case 'http_call':
-    case 'webhook':
-      return Globe;
-    case 'task_creation':
-      return ListChecks;
-    case 'push_notification':
-      return Bell;
-    case 'custom_script':
-      return Code2;
-    case 'connector_action':
-      return Plug;
-    default:
-      return Bot;
-  }
-}
-
-/**
- * Per-action-type color tone — mirrors the flow node-type tinting so
- * action kinds are scannable in the rule's action list. Full Tailwind
- * class strings (JIT) with light + dark variants.
- */
-interface ActionTone {
-  /** Icon color. */
-  icon: string;
-  /** Icon chip (border + bg). */
-  chip: string;
-}
-
-const ACTION_TONE: Record<string, ActionTone> = {
-  field_update: {
-    icon: 'text-blue-600 dark:text-blue-400',
-    chip: 'border-blue-200 bg-blue-50 dark:border-blue-900 dark:bg-blue-950/40',
-  },
-  email_alert: {
-    icon: 'text-violet-600 dark:text-violet-400',
-    chip: 'border-violet-200 bg-violet-50 dark:border-violet-900 dark:bg-violet-950/40',
-  },
-  http_call: {
-    icon: 'text-indigo-600 dark:text-indigo-400',
-    chip: 'border-indigo-200 bg-indigo-50 dark:border-indigo-900 dark:bg-indigo-950/40',
-  },
-  task_creation: {
-    icon: 'text-emerald-600 dark:text-emerald-400',
-    chip: 'border-emerald-200 bg-emerald-50 dark:border-emerald-900 dark:bg-emerald-950/40',
-  },
-  push_notification: {
-    icon: 'text-amber-600 dark:text-amber-400',
-    chip: 'border-amber-200 bg-amber-50 dark:border-amber-900 dark:bg-amber-950/40',
-  },
-  custom_script: {
-    icon: 'text-teal-600 dark:text-teal-400',
-    chip: 'border-teal-200 bg-teal-50 dark:border-teal-900 dark:bg-teal-950/40',
-  },
-  connector_action: {
-    icon: 'text-rose-600 dark:text-rose-400',
-    chip: 'border-rose-200 bg-rose-50 dark:border-rose-900 dark:bg-rose-950/40',
-  },
-  default: {
-    icon: 'text-slate-500 dark:text-slate-400',
-    chip: 'border-slate-200 bg-slate-100 dark:border-slate-800 dark:bg-slate-900/60',
-  },
-};
-
-function actionTone(type: string): ActionTone {
-  switch (type) {
-    case 'field_update':
-      return ACTION_TONE.field_update;
-    case 'email_alert':
-      return ACTION_TONE.email_alert;
-    case 'http_call':
-    case 'webhook':
-      return ACTION_TONE.http_call;
-    case 'task_creation':
-      return ACTION_TONE.task_creation;
-    case 'push_notification':
-      return ACTION_TONE.push_notification;
-    case 'custom_script':
-      return ACTION_TONE.custom_script;
-    case 'connector_action':
-      return ACTION_TONE.connector_action;
-    default:
-      return ACTION_TONE.default;
-  }
-}
-
-function summarizeAction(a: WorkflowAction): string | undefined {
-  switch (a.type) {
-    case 'field_update':
-      // Canonical: { field, value }. Legacy: { objectName, fieldName, value }.
-      return `${a.field ?? (a.objectName ? `${a.objectName}.${a.fieldName ?? '?'}` : '?')} = ${formatLiteral(a.value)}`;
-    case 'email_alert':
-      // Canonical: { template, recipients[] }. Legacy: { templateName, to }.
-      return `template: ${a.template ?? a.templateName ?? '?'} → ${formatRecipients(a)}`;
-    case 'http_call':
-    case 'webhook':
-      return `${String(a.method ?? 'POST').toUpperCase()} ${a.url ?? a.endpoint ?? '?'}`;
-    case 'task_creation':
-      // Canonical: { taskObject, subject, assignedTo?, dueDate? }.
-      return `create ${a.taskObject ?? '?'}${a.assignedTo ? ` → ${a.assignedTo}` : ''}${a.subject ? `: "${a.subject}"` : ''}`;
-    case 'push_notification':
-      return a.title ? `"${a.title}"` : undefined;
-    case 'custom_script':
-      // Canonical: { language, code }.
-      return a.language ? `${a.language}${typeof a.code === 'string' ? ` (${(a.code as string).length} chars)` : ''}` : (a.scriptName as string ?? a.functionName as string ?? undefined);
-    case 'connector_action':
-      return `${a.connectorId ?? '?'}.${a.actionId ?? '?'}`;
-    default:
-      return undefined;
-  }
-}
-
-function formatLiteral(v: unknown): string {
-  if (v == null) return '∅';
-  if (typeof v === 'string') return `"${v}"`;
-  if (typeof v === 'object') return JSON.stringify(v);
-  return String(v);
-}
-
-function formatRecipients(a: WorkflowAction): string {
-  const r = (a.recipients ?? a.to) as unknown;
-  if (Array.isArray(r)) return r.slice(0, 3).join(', ') + (r.length > 3 ? ', …' : '');
-  if (typeof r === 'string') return r;
-  return '—';
-}
-
-export function WorkflowPreview({ draft, editing, selection, onSelectionChange, onPatch, locale }: MetadataPreviewProps) {
-  const d = draft as Record<string, unknown>;
-  const objectName = String(d.objectName ?? d.object ?? '');
-  const triggerType = String(d.triggerType ?? d.trigger ?? '—');
-  const criteria = d.criteria as { source?: string } | string | undefined;
-  const criteriaText =
-    typeof criteria === 'string'
-      ? criteria
-      : (criteria && typeof criteria === 'object' && typeof (criteria as any).source === 'string')
-        ? (criteria as any).source
-        : undefined;
-
-  const actions: WorkflowAction[] = Array.isArray(d.actions) ? (d.actions as WorkflowAction[]) : [];
-  const timeTriggers: TimeTrigger[] = Array.isArray(d.timeTriggers) ? (d.timeTriggers as TimeTrigger[]) : [];
-  const active = d.active !== false;
-  const order = d.executionOrder as number | undefined;
-
-  const designMode = !!(editing && onSelectionChange);
-  const canEdit = designMode && !!onPatch;
-  const selectedId = selection && selection.kind === 'action' ? selection.id : null;
-  const selectAction = (a: WorkflowAction, id: string) => onSelectionChange?.({ kind: 'action', id, label: (a as any).name || a.type || id });
-
-  const handleAddAction = React.useCallback(() => {
-    if (!canEdit) return;
-    const newAction: WorkflowAction = { type: 'field_update', name: '' };
-    const next = appendArray(actions, newAction);
-    onPatch!({ actions: next });
-    const id = `actions[${next.length - 1}]`;
-    onSelectionChange?.({ kind: 'action', id, label: newAction.type });
-  }, [canEdit, actions, onPatch, onSelectionChange]);
-
-  if (!objectName && actions.length === 0 && timeTriggers.length === 0) {
-    return (
-      <PreviewShell hint={`workflow${designMode ? ' · design' : ''}`}>
-        {canEdit ? (
-          <div className="p-3">
-            <button
-              type="button"
-              className="inline-flex items-center gap-1 rounded border border-dashed px-3 py-2 text-xs text-muted-foreground hover:bg-muted/30 hover:text-foreground"
-              onClick={handleAddAction}
-            >
-              <Plus className="h-3 w-3" />
-              {tr('engine.inspector.add.action', locale)}
-            </button>
-          </div>
-        ) : (
-          <PreviewMessage>Set the target object and at least one action to see the workflow preview.</PreviewMessage>
-        )}
-      </PreviewShell>
-    );
-  }
-
-  return (
-    <PreviewShell hint={`workflow · ${actions.length + timeTriggers.reduce((a, t) => a + (t.actions?.length ?? 0), 0)} action(s)`}>
-      <PreviewErrorBoundary>
-        <div className="p-3 space-y-3">
-          {/* Trigger envelope */}
-          <div className="rounded border bg-muted/30 p-3 text-xs space-y-1.5">
-            <div className="flex flex-wrap items-center gap-x-4 gap-y-1">
-              <Pill icon={WorkflowIcon} label="Object" value={objectName || '—'} mono />
-              <Pill icon={PlayCircle} label="When" value={triggerType} />
-              <Pill icon={Power} label="Active" value={active ? 'yes' : 'no'} tone={active ? 'green' : 'amber'} />
-              {order != null && <Pill label="Order" value={String(order)} />}
-            </div>
-            <div className="flex items-start gap-1.5">
-              <Filter className="h-3 w-3 mt-0.5 text-muted-foreground shrink-0" />
-              <span className="text-muted-foreground">Criteria:</span>
-              <code className="font-mono text-foreground break-all">
-                {criteriaText || <span className="italic text-muted-foreground">always</span>}
-              </code>
-            </div>
-          </div>
-
-          {/* Immediate actions */}
-          <Section title="Immediate Actions" count={actions.length}>
-            {actions.length === 0 ? (
-              <Empty>No immediate actions.</Empty>
-            ) : (
-              <ul className="divide-y rounded border bg-background">
-                {actions.map((a, i) => {
-                  const id = `actions[${i}]`;
-                  return <ActionRow key={i} action={a} onClick={designMode ? () => selectAction(a, id) : undefined} selected={selectedId === id} />;
-                })}
-              </ul>
-            )}
-            {canEdit && (
-              <button
-                type="button"
-                className="inline-flex items-center gap-1 rounded border border-dashed px-3 py-1.5 text-xs text-muted-foreground hover:bg-muted/30 hover:text-foreground"
-                onClick={handleAddAction}
-              >
-                <Plus className="h-3 w-3" />
-                {tr('engine.inspector.add.action', locale)}
-              </button>
-            )}
-          </Section>
-
-          {/* Time-dependent actions */}
-          {timeTriggers.length > 0 && (
-            <Section title="Time-Dependent Actions" count={timeTriggers.length}>
-              <ul className="space-y-2">
-                {timeTriggers.map((t, i) => {
-                  const offset = t.offset ?? 0;
-                  const unit = t.unit ?? 'hours';
-                  const base = t.baseField ?? t.baseEvent ?? 'trigger';
-                  const sign = offset >= 0 ? '+' : '';
-                  return (
-                    <li key={i} className="rounded border bg-background">
-                      <div className="flex items-center gap-2 px-3 py-2 text-xs border-b bg-muted/20">
-                        <AlarmClock className="h-3.5 w-3.5 text-muted-foreground" />
-                        <span className="font-mono">
-                          {sign}{offset} {unit}
-                        </span>
-                        <ArrowRight className="h-3 w-3 text-muted-foreground" />
-                        <span className="text-muted-foreground">after</span>
-                        <code className="font-mono">{base}</code>
-                      </div>
-                      {Array.isArray(t.actions) && t.actions.length > 0 ? (
-                        <ul className="divide-y">
-                          {t.actions.map((a, j) => {
-                            const id = `timeTriggers[${i}].actions[${j}]`;
-                            return <ActionRow key={j} action={a as WorkflowAction} onClick={designMode ? () => selectAction(a as WorkflowAction, id) : undefined} selected={selectedId === id} />;
-                          })}
-                        </ul>
-                      ) : (
-                        <Empty>No actions scheduled at this offset.</Empty>
-                      )}
-                    </li>
-                  );
-                })}
-              </ul>
-            </Section>
-          )}
-        </div>
-      </PreviewErrorBoundary>
-    </PreviewShell>
-  );
-}
-
-function ActionRow({ action, onClick, selected }: { action: WorkflowAction; onClick?: () => void; selected?: boolean }) {
-  const Icon = actionIcon(action.type);
-  const tone = actionTone(action.type);
-  const summary = summarizeAction(action);
-  const aName = (action as any).name as string | undefined;
-  return (
-    <li
-      className={`flex items-start gap-2 px-3 py-2 text-xs ${onClick ? 'cursor-pointer hover:bg-accent/40' : ''} ${selected ? 'bg-primary/5 ring-1 ring-primary' : ''}`}
-      onClick={onClick ? (e) => { e.stopPropagation(); onClick(); } : undefined}
-    >
-      <span className={cn('mt-0.5 inline-flex h-5 w-5 shrink-0 items-center justify-center rounded border', tone.chip)}>
-        <Icon className={cn('h-3 w-3', tone.icon)} />
-      </span>
-      <div className="min-w-0 flex-1">
-        <div className="flex items-baseline gap-2 flex-wrap">
-          <span className="font-medium">{prettyActionType(action.type)}</span>
-          {aName && <code className="font-mono text-[10px] text-foreground">{aName}</code>}
-          <span className="font-mono text-[10px] text-muted-foreground">{action.type}</span>
-        </div>
-        {summary && <div className="text-muted-foreground font-mono break-all">{summary}</div>}
-      </div>
-    </li>
-  );
-}
-
-function prettyActionType(t: string): string {
-  return t
-    .split('_')
-    .map((w) => w.charAt(0).toUpperCase() + w.slice(1))
-    .join(' ');
-}
-
-function Section({ title, count, children }: { title: string; count?: number; children: React.ReactNode }) {
-  return (
-    <div className="space-y-1.5">
-      <div className="flex items-center gap-2 text-[11px] font-medium text-muted-foreground uppercase tracking-wider">
-        <span>{title}</span>
-        {count != null && <span className="opacity-70">({count})</span>}
-      </div>
-      {children}
-    </div>
-  );
-}
-
-function Empty({ children }: { children: React.ReactNode }) {
-  return <div className="text-xs text-muted-foreground italic px-2 py-1.5">{children}</div>;
-}
-
-function Pill({
-  icon: Icon,
-  label,
-  value,
-  tone = 'gray',
-  mono = false,
-}: {
-  icon?: React.ComponentType<{ className?: string }>;
-  label: string;
-  value: string;
-  tone?: 'gray' | 'green' | 'amber';
-  mono?: boolean;
-}) {
-  const cls =
-    tone === 'green'
-      ? 'text-emerald-700'
-      : tone === 'amber'
-        ? 'text-amber-700'
-        : 'text-foreground';
-  return (
-    <span className="inline-flex items-center gap-1">
-      {Icon && <Icon className="h-3 w-3 text-muted-foreground" />}
-      <span className="text-muted-foreground">{label}:</span>
-      <span className={`font-medium ${cls} ${mono ? 'font-mono' : ''}`}>{value}</span>
-    </span>
-  );
-}
diff --git a/packages/app-shell/src/views/metadata-admin/previews/index.ts b/packages/app-shell/src/views/metadata-admin/previews/index.ts
index 8985be99a..7e55d7308 100644
--- a/packages/app-shell/src/views/metadata-admin/previews/index.ts
+++ b/packages/app-shell/src/views/metadata-admin/previews/index.ts
@@ -18,7 +18,6 @@ import { AppPreview } from './AppPreview';
 import { ObjectPreview } from './ObjectPreview';
 import { EmailTemplatePreview } from './EmailTemplatePreview';
 import { FlowPreview } from './FlowPreview';
-import { WorkflowPreview } from './WorkflowPreview';
 import { AgentPreview } from './AgentPreview';
 import { ToolPreview } from './ToolPreview';
 import { PermissionPreview } from './PermissionPreview';
@@ -50,7 +49,9 @@ export function registerBuiltinPreviews(): void {
   // the Flow canvas with its `approve` / `reject` branches; no standalone
   // approval-process preview.
   registerMetadataPreview('flow', FlowPreview);
-  registerMetadataPreview('workflow', WorkflowPreview);
+  // ADR-0020: `workflow` retired as a metadata type — record state machines
+  // are now a `state_machine` validation rule (rendered by ValidationPreview)
+  // and side-effecting automation is a Flow. No standalone workflow preview.
   registerMetadataPreview('job', JobPreview);
   // AI
   registerMetadataPreview('agent', AgentPreview);
diff --git a/packages/core/src/validation/__tests__/object-validation-engine.test.ts b/packages/core/src/validation/__tests__/object-validation-engine.test.ts
index 11b49ee6b..409fdb0cf 100644
--- a/packages/core/src/validation/__tests__/object-validation-engine.test.ts
+++ b/packages/core/src/validation/__tests__/object-validation-engine.test.ts
@@ -190,94 +190,79 @@ describe('ObjectValidationEngine', () => {
   });
 
   describe('StateMachineValidation', () => {
+    // ADR-0020 flat FSM: `field` + `{ from: [allowedTo] }` map (no guards).
+    const orderFlow: StateMachineValidation = {
+      type: 'state_machine',
+      name: 'order_status_flow',
+      active: true,
+      events: ['update'],
+      severity: 'error',
+      message: 'Invalid status transition',
+      field: 'status',
+      transitions: {
+        draft: ['submitted'],
+        submitted: ['approved', 'rejected'],
+        approved: ['completed'],
+      },
+    };
+
     it('should allow valid state transition', async () => {
       const engine = new ObjectValidationEngine();
-      const rule: StateMachineValidation = {
-        type: 'state_machine',
-        name: 'order_status_flow',
-        active: true,
-        events: ['update'],
-        severity: 'error',
-        message: 'Invalid status transition',
-        stateField: 'status',
-        transitions: [
-          { from: 'draft', to: 'submitted' },
-          { from: 'submitted', to: 'approved' },
-          { from: 'submitted', to: 'rejected' },
-          { from: 'approved', to: 'completed' },
-        ],
-      };
-
       const context: ObjectValidationContext = {
         record: { status: 'submitted' },
         oldRecord: { status: 'draft' },
       };
 
-      const results = await engine.validateRecord([rule], context, 'update');
+      const results = await engine.validateRecord([orderFlow], context, 'update');
       expect(results).toHaveLength(0);
     });
 
     it('should prevent invalid state transition', async () => {
       const engine = new ObjectValidationEngine();
-      const rule: StateMachineValidation = {
-        type: 'state_machine',
-        name: 'order_status_flow',
-        active: true,
-        events: ['update'],
-        severity: 'error',
-        message: 'Invalid status transition',
-        stateField: 'status',
-        transitions: [
-          { from: 'draft', to: 'submitted' },
-          { from: 'submitted', to: 'approved' },
-        ],
-      };
-
       const context: ObjectValidationContext = {
         record: { status: 'approved' },
         oldRecord: { status: 'draft' },
       };
 
-      const results = await engine.validateRecord([rule], context, 'update');
+      const results = await engine.validateRecord([orderFlow], context, 'update');
       expect(results).toHaveLength(1);
-      expect(results[0]).toMatchObject({
-        valid: false,
-      });
+      expect(results[0]).toMatchObject({ valid: false });
       expect(results[0].message).toContain('transition');
     });
 
-    it('should support conditional state transitions', async () => {
+    it('should allow the initial assignment on insert (no prior state)', async () => {
       const engine = new ObjectValidationEngine();
-      const rule: StateMachineValidation = {
-        type: 'state_machine',
-        name: 'conditional_transition',
-        active: true,
-        events: ['update'],
-        severity: 'error',
-        message: 'Invalid transition',
-        stateField: 'status',
-        transitions: [
-          {
-            from: 'pending',
-            to: 'approved',
-            condition: 'amount < 1000',
-          },
-        ],
+      const context: ObjectValidationContext = {
+        record: { status: 'draft' },
+        oldRecord: undefined,
       };
 
-      const context1: ObjectValidationContext = {
-        record: { status: 'approved', amount: 500 },
-        oldRecord: { status: 'pending', amount: 500 },
+      const results = await engine.validateRecord([orderFlow], context, 'insert');
+      expect(results).toHaveLength(0);
+    });
+
+    it('should be a no-op when the state field is unchanged', async () => {
+      const engine = new ObjectValidationEngine();
+      const context: ObjectValidationContext = {
+        record: { status: 'draft', other: 'changed' },
+        oldRecord: { status: 'draft', other: 'original' },
       };
-      const results1 = await engine.validateRecord([rule], context1, 'update');
-      expect(results1).toHaveLength(0);
 
-      const context2: ObjectValidationContext = {
-        record: { status: 'approved', amount: 2000 },
-        oldRecord: { status: 'pending', amount: 2000 },
+      const results = await engine.validateRecord([orderFlow], context, 'update');
+      expect(results).toHaveLength(0);
+    });
+
+    it('should leave an undeclared from-state unconstrained (lenient)', async () => {
+      const engine = new ObjectValidationEngine();
+      const context: ObjectValidationContext = {
+        // `completed` is a declared dead-end (no entry as a from-key), so any
+        // outbound transition is left unconstrained rather than rejected.
+        record: { status: 'reopened' },
+        oldRecord: { status: 'completed' },
       };
-      const results2 = await engine.validateRecord([rule], context2, 'update');
-      expect(results2).toHaveLength(1);
+
+      const results = await engine.validateRecord([orderFlow], context, 'update');
+      expect(results).toHaveLength(0);
     });
   });
 
diff --git a/packages/core/src/validation/validators/object-validation-engine.ts b/packages/core/src/validation/validators/object-validation-engine.ts
index 4c8ac81c3..31fd971b5 100644
--- a/packages/core/src/validation/validators/object-validation-engine.ts
+++ b/packages/core/src/validation/validators/object-validation-engine.ts
@@ -423,38 +423,33 @@ export class ObjectValidationEngine {
     rule: StateMachineValidation,
     context: ObjectValidationContext
   ): ObjectValidationResult {
-    const currentState = context.record[rule.stateField];
-    const previousState = context.oldRecord?.[rule.stateField];
+    // ADR-0020 flat FSM: a `field` plus a `{ from: [allowedTo] }` map.
+    // Semantics mirror the server-side rule-validator:
+    //   - insert / no prior state           → allow (initial assignment)
+    //   - field unchanged (from === to)      → allow (no transition)
+    //   - `from` not declared in the map      → lenient allow (unconstrained)
+    //   - `to` ∉ transitions[from]           → reject
+    const currentState = context.record[rule.field];
+    const previousState = context.oldRecord?.[rule.field];
+
+    // No prior state (insert) — any initial value is allowed.
+    if (previousState === undefined || previousState === null) {
+      return { valid: true };
+    }
 
-    // If no previous state (insert), allow any state
-    if (!previousState) {
+    // The state field wasn't part of this change — nothing to police.
+    if (previousState === currentState) {
       return { valid: true };
     }
 
-    // Check if transition is allowed
-    for (const transition of rule.transitions) {
-      const fromStates = Array.isArray(transition.from) ? transition.from : [transition.from];
-      
-      if (!fromStates.includes(previousState)) {
-        continue;
-      }
-      
-      if (transition.to !== currentState) {
-        continue;
-      }
-      
-      // Check condition if specified
-      if (transition.condition) {
-        const conditionMet = this.expressionEvaluator.evaluate(
-          transition.condition,
-          context.record
-        );
-        if (!conditionMet) {
-          continue;
-        }
-      }
-      
-      // Valid transition found
+    const allowed = rule.transitions[previousState];
+
+    // `from` state not declared — leave it unconstrained (lenient).
+    if (allowed === undefined) {
+      return { valid: true };
+    }
+
+    if (allowed.includes(currentState)) {
       return { valid: true };
     }
 
diff --git a/packages/types/src/data-protocol.ts b/packages/types/src/data-protocol.ts
index 6156cc820..70e80d174 100644
--- a/packages/types/src/data-protocol.ts
+++ b/packages/types/src/data-protocol.ts
@@ -888,26 +888,22 @@ export interface UniquenessValidation extends BaseValidation {
 }
 
 /**
- * State machine validation (ObjectStack Spec v2.0.1)
- * Enforces valid state transitions
+ * State machine validation (ObjectStack Spec — ADR-0020)
+ * Enforces valid state transitions on a single state field.
+ *
+ * ADR-0020 converged record state machines onto this one flat rule: a state
+ * `field` plus a `transitions` map of `{ fromState: [allowedToStates] }`.
+ * (The legacy `{ stateField, transitions: Array<{from,to,condition}> }`
+ * shape and the separate `workflow` metadata type were retired.)
  */
 export interface StateMachineValidation extends BaseValidation {
   type: 'state_machine';
-  
-  /** Field containing the state */
-  stateField: string;
-  
-  /** Allowed state transitions */
-  transitions: Array<{
-    /** Source state(s) */
-    from: string | string[];
-    
-    /** Target state */
-    to: string;
-    
-    /** Optional condition that must be true */
-    condition?: string;
-  }>;
+
+  /** Field containing the state (e.g. `status`). */
+  field: string;
+
+  /** Map of `{ fromState: [allowedToStates] }`. */
+  transitions: Record<string, string[]>;
 }
 
 /**