@@ -0,0 +1,16 @@
+---
+'@objectstack/runtime': patch
+---
+
+fix(runtime): the HTTP dispatcher answers the engine's `DuplicateRecordError` with the wire code `UNIQUE_VIOLATION`, not the engine's in-process `DUPLICATE_RECORD`, with `developerMessage`, `object` and `field` in `error.details` (#23686)
+
+**Wire change at the dispatcher's doors: `409 DUPLICATE_RECORD` becomes `409 UNIQUE_VIOLATION`.** It applies wherever a dispatcher domain hands a caught engine throw to its shared error writer (`HttpDispatcher`'s thrown-error envelope). Measured: `POST /actions/:object/:action`, for a handler or a declarative `operation: 'update'` action whose write repeats a unique value, and the activation doors `POST /actions/_activation/:object/:action` and `POST /security/_activation/:type/:name`, for a flip that loses a race on the activation ledger's unique key. A client of these doors (`@objectstack/hono`'s `createHonoApp`, or any host serving the dispatcher) that matched `code === 'DUPLICATE_RECORD'` on that refusal must match `code === 'UNIQUE_VIOLATION'` instead. That is what the REST server and both Hono doors already answer for the same refusal.
+
+Why: the maintainer ruled one wire spelling for a unique-constraint refusal on every route, `UNIQUE_VIOLATION` (recorded in commit 65846bc46). The REST server, the batch and import rows and the Hono doors already reported it. The dispatcher's own writer reported the engine's spelling.
+
+- FROM `{"success":false,"error":{"code":"DUPLICATE_RECORD","message":"Duplicate record refused on 'udoc': …","httpStatus":409}}`
+- TO `{"success":false,"error":{"code":"UNIQUE_VIOLATION","message":"Duplicate record refused on 'udoc': …","httpStatus":409,"details":{"developerMessage":"Duplicate record refused on 'udoc': …","object":"udoc"}}}`
+
+`details` carries what the REST server's answer carries beside its code, each field only when the producer stated it: `developerMessage`, `object`, and `field` when the driver named the conflicting column. The status stays `409` and the `message` is unchanged. Only the engine's `DuplicateRecordError` is translated, recognised by its registered code and its class name together. A handler or hook that throws the registered `DUPLICATE_RECORD` without being that class keeps its own code. Inside the engine, `DuplicateRecordError.code` is still `DUPLICATE_RECORD`, so an in-process caller (a hook, a flow node) is unaffected. Other `409` answers at these doors (`DELETE_RESTRICTED`, `CONCURRENT_UPDATE`) are unchanged.
+
+Clause-②: no
@@ -0,0 +1,301 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * [#23686] The runtime dispatcher's own catch arms answer the engine's
+ * `DuplicateRecordError` with the ruled wire spelling, `409 UNIQUE_VIOLATION`.
+ *
+ * Maintainer ruling (2026-09-03, recorded in commit 65846bc46): one wire
+ * spelling on every route, `UNIQUE_VIOLATION`; the row reports it too.
+ *
+ * ## What was wrong
+ *
+ * `HttpDispatcher.errorFromThrown` is the one writer the dispatcher domains
+ * hand a caught throw to. It passed the engine's registered in-process code
+ * through unchanged, so a door whose catch arm reaches it answered
+ * `409 DUPLICATE_RECORD` for a repeated unique value, while `RestServer`'s
+ * arm, the batch and import rows and both Hono doors answer the same throw as
+ * `UNIQUE_VIOLATION`. Measured before the fix on the rig below:
+ *
+ *  - `POST /actions/:object/:action`, a handler whose engine write repeats a
+ *    unique value, and a declarative `operation: 'update'` action doing the
+ *    same: `409 {"code":"DUPLICATE_RECORD", …, "httpStatus":409}`, no `details`;
+ *  - `POST /security/_activation/:type/:name` and
+ *    `POST /actions/_activation/:object/:action`, a flip whose ledger read
+ *    misses the row a concurrent flip is inserting (two real concurrent
+ *    flips reproduce it): the same answer, for `sys_metadata_activation`'s
+ *    `(metadata_type, name)` key.
+ *
+ * ## The rig
+ *
+ * A REAL store per describe: better-sqlite3 `:memory:`, the real `ObjectQL`
+ * engine, so every duplicate here is the engine's own envelope over a real
+ * driver refusal, not a double's. The dispatcher is reached the way
+ * `@objectstack/hono`'s catch-all reaches it, `dispatch()` over a real Fetch
+ * `Request`, with the identity step the one stubbed seam; the activation
+ * doors are entered at their domain handlers, as their sibling pins do.
+ *
+ * Codes and key presence are asserted, never wording.
+ */
+
+import { describe, it, expect, beforeAll, afterAll } from 'vitest';
+import { ObjectQL, DuplicateRecordError, ObjectStoreActionActivationStore } from '@objectstack/objectql';
+import { SqlDriver } from '@objectstack/driver-sql';
+import { ObjectStackProtocolImplementation } from '@objectstack/metadata-protocol';
+import { SysMetadataActivation } from '@objectstack/platform-objects/system';
+import { HttpDispatcher } from './http-dispatcher.js';
+import type { HttpProtocolContext } from './http-dispatcher.js';
+import { bindTestSecurityCatalog } from './security/security-catalog.testkit.js';
+
+const PREFIX = '/api/v1';
+/** `registry.registerObject` requires a package id (see the sibling real-stack tests). */
+const TEST_PACKAGE_ID = 'objectstack-test';
+const LEDGER = 'sys_metadata_activation';
+
+/** The value `r1` holds; every write below that repeats it is refused by the unique key. */
+const TAKEN = 'taken@example.com';
+
+const UDOC = {
+    name: 'udoc',
+    label: 'Unique doc',
+    fields: {
+        id: { name: 'id', type: 'text' as const, primaryKey: true, label: 'ID' },
+        name: { name: 'name', type: 'text' as const, label: 'Name' },
+        email: { name: 'email', type: 'text' as const, label: 'Email', unique: true },
+    },
+    actions: [
+        { name: 'add_duplicate', label: 'Add duplicate', type: 'script', target: 'add_duplicate' },
+        { name: 'take_email', label: 'Take email', type: 'script', operation: 'update', patch: { email: TAKEN } },
+        { name: 'throw_named_duplicate', label: 'Throw named duplicate', type: 'script', target: 'throw_named_duplicate' },
+        { name: 'speak_duplicate', label: 'Speak duplicate', type: 'script', target: 'speak_duplicate' },
+        { name: 'delete_parent', label: 'Delete parent', type: 'script', target: 'delete_parent' },
+    ],
+};
+
+const UPARENT = {
+    name: 'uparent',
+    label: 'Parent',
+    fields: {
+        id: { name: 'id', type: 'text' as const, primaryKey: true, label: 'ID' },
+        name: { name: 'name', type: 'text' as const, label: 'Name' },
+    },
+};
+
+const UCHILD = {
+    name: 'uchild',
+    label: 'Child',
+    fields: {
+        id: { name: 'id', type: 'text' as const, primaryKey: true, label: 'ID' },
+        name: { name: 'name', type: 'text' as const, label: 'Name' },
+        parent: { name: 'parent', type: 'lookup' as const, reference: 'uparent', deleteBehavior: 'restrict', label: 'Parent' },
+    },
+};
+
+const MEMBER = { userId: 'u_member', isSystem: false };
+
+const ADMIN = (): HttpProtocolContext => ({
+    request: {},
+    environmentId: 'platform',
+    executionContext: { userId: 'u_admin', systemPermissions: ['manage_metadata'] },
+} as unknown as HttpProtocolContext);
+
+const liveEngines: ObjectQL[] = [];
+afterAll(async () => {
+    while (liveEngines.length) {
+        try { await liveEngines.pop()?.destroy(); } catch { /* noop */ }
+    }
+});
+
+async function bootEngine(objects: readonly object[]): Promise<ObjectQL> {
+    const engine = new ObjectQL();
+    liveEngines.push(engine);
+    engine.registerDriver(new SqlDriver({
+        client: 'better-sqlite3',
+        connection: { filename: ':memory:' },
+        useNullAsDefault: true,
+    }), true);
+    await engine.init();
+    for (const o of objects) engine.registry.registerObject(o as any, TEST_PACKAGE_ID);
+    await engine.syncSchemas();
+    return engine;
+}
+
+function dispatcherOver(services: Record<string, unknown>): HttpDispatcher {
+    const get = (n: string) => services[n] ?? null;
+    const kernel: any = { context: { getService: get }, getService: get, getServiceAsync: async (n: string) => get(n) };
+    const dispatcher = new HttpDispatcher(kernel);
+    (dispatcher as any).timedResolveExecutionContext = async () => ({ ...MEMBER });
+    return dispatcher;
+}
+
+/** `POST /api/v1/actions/<rest>` as `@objectstack/hono`'s catch-all hands it to `dispatch()`. */
+async function postAction(dispatcher: HttpDispatcher, rest: string) {
+    const path = `/actions/${rest}`;
+    const request = new Request(`http://localhost${PREFIX}${path}`, {
+        method: 'POST',
+        headers: { 'content-type': 'application/json' },
+        body: '{}',
+    });
+    const res: any = await dispatcher.dispatch('POST', path, {}, {}, { request } as any, PREFIX);
+    return res.response as { status: number; body: any };
+}
+
+/** The answer a repeated unique value earns at this door: the ruled code, and the REST arm's fields. */
+function expectUniqueViolation(response: { status: number; body: any }, detailKeys: readonly string[], object: string) {
+    expect(response.status, JSON.stringify(response.body)).toBe(409);
+    const error = response.body?.error;
+    expect(error?.code).toBe('UNIQUE_VIOLATION');
+    expect(error?.httpStatus).toBe(409);
+    expect(typeof error?.message).toBe('string');
+    expect(Object.keys(error?.details ?? {}).sort()).toEqual([...detailKeys].sort());
+    expect(error.details.object).toBe(object);
+    expect(typeof error.details.developerMessage).toBe('string');
+    // `DUPLICATE_RECORD` is a registered member, so nothing was demoted.
+    expect(error).not.toHaveProperty('declaredCode');
+    // The in-process spelling does not cross, and neither does the driver's text.
+    const wire = JSON.stringify(response.body);
+    expect(wire).not.toContain('DUPLICATE_RECORD');
+    expect(wire).not.toContain('UNIQUE constraint failed');
+}
+
+describe('[#23686] the actions door answers the engine\'s duplicate as 409 UNIQUE_VIOLATION', () => {
+    let dispatcher: HttpDispatcher;
+    let engine: ObjectQL;
+
+    beforeAll(async () => {
+        engine = await bootEngine([UDOC, UPARENT, UCHILD]);
+        const ql = engine as any;
+        ql.registerAction('udoc', 'add_duplicate', async (ctx: any) => {
+            await ctx.engine.insert('udoc', { id: 'r_dup', name: 'second', email: TAKEN });
+            return { written: true };
+        });
+        ql.registerAction('udoc', 'throw_named_duplicate', async () => {
+            // The engine's own class, stating the column the driver named.
+            throw new DuplicateRecordError('udoc', new Error('driver refusal'), 'email');
+        });
+        ql.registerAction('udoc', 'speak_duplicate', async () => {
+            // A producer that SPEAKS the registered code without being the engine's class.
+            throw Object.assign(new Error('That address is already on file'), { code: 'DUPLICATE_RECORD', status: 409 });
+        });
+        ql.registerAction('udoc', 'delete_parent', async (ctx: any) => {
+            await ctx.engine.delete('uparent', 'p1');
+            return { deleted: true };
+        });
+        await engine.insert('udoc', { id: 'r1', name: 'first', email: TAKEN });
+        await engine.insert('udoc', { id: 'r2', name: 'other', email: 'other@example.com' });
+        await engine.insert('uparent', { id: 'p1', name: 'kept' });
+        await engine.insert('uchild', { id: 'c1', name: 'dependent', parent: 'p1' });
+        const protocol = new ObjectStackProtocolImplementation(engine as any);
+        dispatcher = dispatcherOver({ objectql: engine, data: engine, protocol });
+    }, 60_000);
+
+    it('a handler whose engine write repeats a unique value', async () => {
+        const response = await postAction(dispatcher, 'udoc/add_duplicate');
+
+        // The driver names no single column: the index is the tenancy-scoped composite.
+        expectUniqueViolation(response, ['developerMessage', 'object'], 'udoc');
+        // Non-vacuity: the refusal is real, nothing was written.
+        expect(await engine.find('udoc', { where: { email: TAKEN } })).toHaveLength(1);
+    });
+
+    it('a declarative `operation: \'update\'` action whose write repeats a unique value', async () => {
+        const response = await postAction(dispatcher, 'udoc/take_email/r2');
+
+        expectUniqueViolation(response, ['developerMessage', 'object'], 'udoc');
+        expect(((await engine.findOne('udoc', { where: { id: 'r2' } })) as any)?.email).toBe('other@example.com');
+    });
+
+    it('the engine\'s class stating a column: `field` rides `details` beside the other two', async () => {
+        const response = await postAction(dispatcher, 'udoc/throw_named_duplicate');
+
+        expectUniqueViolation(response, ['developerMessage', 'field', 'object'], 'udoc');
+        expect(response.body.error.details.field).toBe('email');
+    });
+
+    it('CONTROL: a producer that merely speaks `DUPLICATE_RECORD` keeps its own code and body', async () => {
+        const response = await postAction(dispatcher, 'udoc/speak_duplicate');
+
+        expect(response.status).toBe(409);
+        expect(response.body?.error?.code).toBe('DUPLICATE_RECORD');
+        expect(response.body?.error).not.toHaveProperty('details');
+        expect(response.body?.error).not.toHaveProperty('declaredCode');
+    });
+
+    it('CONTROL: another engine 409 (`DELETE_RESTRICTED`) keeps its code and its body', async () => {
+        const response = await postAction(dispatcher, 'udoc/delete_parent');
+
+        expect(response.status).toBe(409);
+        expect(response.body?.error?.code).toBe('DELETE_RESTRICTED');
+        expect(response.body?.error).not.toHaveProperty('details');
+        expect(await engine.find('uparent', { where: { id: 'p1' } })).toHaveLength(1);
+    });
+});
+
+/**
+ * The engine as a flip that races another sees it: its read of the activation
+ * ledger misses the row the other flip has inserted, so its own insert is the
+ * one the ledger's unique `(metadata_type, name)` key refuses. Every other
+ * call reaches the real engine, the insert included, so the refusal is the
+ * engine's own envelope over a real driver error. Two real concurrent flips
+ * reproduce the same answer; this holds the race window open so the pin does
+ * not depend on scheduling.
+ */
+function ledgerReadMissingTheRacer(engine: ObjectQL): ObjectQL {
+    return new Proxy(engine, {
+        get(target, prop) {
+            if (prop === 'find') {
+                return async (object: string, options?: unknown) =>
+                    object === LEDGER ? [] : (target as any).find(object, options);
+            }
+            const value = Reflect.get(target, prop, target);
+            return typeof value === 'function' ? value.bind(target) : value;
+        },
+    });
+}
+
+describe('[#23686] the activation doors answer a ledger write that loses a race as 409 UNIQUE_VIOLATION', () => {
+    let engine: ObjectQL;
+    let racing: ObjectQL;
+    let dispatcher: HttpDispatcher;
+
+    beforeAll(async () => {
+        engine = await bootEngine([UDOC, SysMetadataActivation]);
+        bindTestSecurityCatalog(engine, {
+            positions: [{ name: 'sales_rep', permissionSets: ['sales_access'] }],
+            permissions: [
+                { name: 'sales_access', systemPermissions: ['cap_sales'] },
+                { name: 'admin_full_access', systemPermissions: ['manage_metadata'] },
+            ],
+        });
+        (engine as any).registerAction('udoc', 'add_duplicate', async () => ({ ok: true }));
+        racing = ledgerReadMissingTheRacer(engine);
+        const store = new ObjectStoreActionActivationStore(racing as any);
+        await store.probe();
+        (engine as any).setActionActivationStore(store);
+        dispatcher = dispatcherOver({ objectql: racing, data: racing });
+    }, 60_000);
+
+    const ledgerRows = async (type: string, name: string) =>
+        engine.find(LEDGER, { where: { metadata_type: type, name } });
+
+    it('`POST /security/_activation/position/:name` (catalog activation)', async () => {
+        const flip = () => dispatcher.handleSecurity('/_activation/position/sales_rep', 'POST', { enabled: false }, {}, ADMIN());
+
+        const first: any = await flip();
+        expect(first.response?.status, JSON.stringify(first.response?.body)).toBe(200);
+        const racer: any = await flip();
+
+        expectUniqueViolation(racer.response, ['developerMessage', 'object'], LEDGER);
+        expect(await ledgerRows('position', 'sales_rep')).toHaveLength(1);
+    });
+
+    it('`POST /actions/_activation/:object/:action` (action activation)', async () => {
+        const flip = () => dispatcher.handleActions('/_activation/udoc/add_duplicate', 'POST', { enabled: false }, ADMIN());
+
+        const first: any = await flip();
+        expect(first.response?.status, JSON.stringify(first.response?.body)).toBe(200);
+        const racer: any = await flip();
+
+        expectUniqueViolation(racer.response, ['developerMessage', 'object'], LEDGER);
+        expect(await ledgerRows('action', 'add_duplicate')).toHaveLength(1);
+    });
+});