@@ -0,0 +1,18 @@
+---
+'@objectstack/service-datasource': patch
+---
+
+fix(service-datasource)!: creating a runtime datasource refuses `drivers`, the name the driver-catalog route answers, so a datasource is never created that its edit form cannot load (#29164)
+
+Clause-②: no (narrowing) — `POST /api/v1/datasources` with `name: 'drivers'`, which answered 201 before, now answers 400 `DATASOURCE_ADMIN_ERROR` naming the reserved name. Nothing is widened.
+Metadata-protocol: none
+
+<!-- adr-0087: not-required (no-migration-prescription) No schema key, export or stored shape changes: the runtime datasource-admin create door refuses one more name, the way it already refused `default`. A stored row of that name is not rewritten or refused, so there is nothing for a migration to rewrite and no tombstone. -->
+
+**BREAKING** accept-set narrowing at the datasource-admin create door (`@objectstack/service-datasource`).
+
+- **Before.** `GET /api/v1/datasources/drivers` is the driver catalog, mounted ahead of `GET /api/v1/datasources/:name`. A runtime datasource named `drivers` was created and listed, but its detail read always answered the catalog, so Setup → Datasources could never open its edit form.
+- **Now.** Create refuses every literal path segment the admin routes mount beside a same-method `/datasources/:name` route; today that is `drivers` alone. The refusal is the same 400 `DATASOURCE_ADMIN_ERROR` that `default` already answers. `test` stays creatable: `POST /datasources/test` (the unsaved-draft probe) sits beside no `POST /datasources/:name`, so a datasource named `test` keeps every by-name door.
+- **Stored rows.** A `drivers` row created before this release is not refused or rewritten. It stays listed, patchable, removable and probe-able by name; its detail read still answers the catalog.
+
+**The remedy.** Create the datasource under another name. For a stored `drivers` row, create the same connection under another name, move the objects bound to `drivers` onto it, then remove `drivers` (`DELETE /api/v1/datasources/drivers`, which refuses while any object is still bound).
@@ -278,6 +278,9 @@ through the same datasource connection path — one failure verdict, one escape
 hatch, and a real `status` for the primary DB in **Setup → Datasources**. The
 name `default` is host-reserved: an app bundle declaring a datasource with that
 name is rejected at load.
+The name `drivers` is reserved at the datasource admin API: creating a runtime
+datasource under it is refused, because `GET /api/v1/datasources/drivers` is the
+driver catalog, so a datasource of that name could never be opened by name.
 
 <Callout type="warn">
 `OS_ALLOW_DRIVER_CONNECT_FAILURE=1` boots anyway, in an explicitly degraded
 
@@ -0,0 +1,207 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * Route-shadowed datasource names (#29164).
+ *
+ * `GET /datasources/drivers` is the driver catalog, mounted before
+ * `GET /datasources/:name`, so a runtime datasource named `drivers` was
+ * created (201) and listed while its detail read — the edit form's load —
+ * always answered the catalog. Create now refuses every literal the registrar
+ * mounts beside a same-method `/:name` route, the way it refuses the
+ * host-owned `default`.
+ *
+ * Two halves:
+ *  - the DRIFT PIN derives the shadowing literals from what
+ *    `registerDatasourceAdminRoutes` actually mounts (a capturing mock
+ *    `IHttpServer`, the route-ledger conformance seam) and holds the reserved
+ *    list equal to them, so a new literal sibling of `/:name` mounted without
+ *    a reservation fails here;
+ *  - the DOOR cases run the real `HonoHttpServer` over a real
+ *    `DatasourceAdminService`: the refusal envelope, the service never
+ *    writing, `default` unchanged, and the names that stay creatable.
+ */
+
+import { describe, it, expect, vi } from 'vitest';
+import { HonoHttpServer } from '@objectstack/plugin-hono-server';
+import { registerDatasourceAdminRoutes } from '../admin-routes.js';
+import {
+  DatasourceAdminService,
+  type DatasourceAdminServiceConfig,
+  type StoredDatasource,
+} from '../datasource-admin-service.js';
+import { ROUTE_SHADOWED_DATASOURCE_NAMES } from '../datasource-route-reserved-names.js';
+import {
+  ENTITLED_CREDENTIAL,
+  createSessionAuthService,
+  createGrantsEngine,
+} from './entitled-caller.fixture.js';
+
+const BASE = '/api/v1';
+const ROOT = `${BASE}/datasources`;
+const VERBS = ['get', 'post', 'put', 'patch', 'delete'] as const;
+
+/** Every `[VERB, path]` the registrar mounts at the default base. */
+function enumerateMounts(): Array<[string, string]> {
+  const server = Object.fromEntries([
+    ...VERBS.map((v) => [v, vi.fn()]),
+    ['use', vi.fn()],
+    ['listen', vi.fn().mockResolvedValue(undefined)],
+    ['close', vi.fn().mockResolvedValue(undefined)],
+  ]) as Record<(typeof VERBS)[number], ReturnType<typeof vi.fn>>;
+  const ctx = { getService: () => undefined, logger: { debug: vi.fn(), info: vi.fn(), warn: vi.fn(), error: vi.fn() } };
+  registerDatasourceAdminRoutes(server as never, ctx as never, BASE);
+  return VERBS.flatMap((v) => server[v].mock.calls.map((c): [string, string] => [v.toUpperCase(), String(c[0])]));
+}
+
+/**
+ * The literal single segments under the root that share a method with a
+ * `/:name` route — the names that route would never see.
+ */
+function shadowingLiterals(mounts: Array<[string, string]>): string[] {
+  const byNameMethods = new Set(mounts.filter(([, p]) => p === `${ROOT}/:name`).map(([m]) => m));
+  const literals = new Set<string>();
+  for (const [method, path] of mounts) {
+    if (!path.startsWith(`${ROOT}/`)) continue;
+    const rest = path.slice(ROOT.length + 1);
+    if (rest.includes('/') || rest.startsWith(':')) continue;
+    if (byNameMethods.has(method)) literals.add(rest);
+  }
+  return [...literals].sort();
+}
+
+describe('reserved datasource names ↔ the registrar\'s literal siblings of /:name', () => {
+  it('reserves exactly the literals that shadow a same-method /:name route', () => {
+    const mounts = enumerateMounts();
+    // Control: the enumeration saw the by-name read and a literal at all, so
+    // an empty answer below could not be a silent nothing-enumerated.
+    expect(mounts).toContainEqual(['GET', `${ROOT}/:name`]);
+    expect(mounts).toContainEqual(['POST', `${ROOT}/test`]);
+
+    expect([...ROUTE_SHADOWED_DATASOURCE_NAMES].sort()).toEqual(shadowingLiterals(mounts));
+  });
+
+  it('a literal beside a /:name route of ANOTHER method is not a shadowing one', () => {
+    // `POST /datasources/test` shares no method with a `/:name` route; were a
+    // `GET /datasources/test` mounted, `test` would join the derived set and
+    // the pin above would fail until it is reserved.
+    expect(shadowingLiterals([['POST', `${ROOT}/test`], ['GET', `${ROOT}/:name`]])).toEqual([]);
+    expect(shadowingLiterals([['GET', `${ROOT}/test`], ['GET', `${ROOT}/:name`]])).toEqual(['test']);
+  });
+});
+
+// ---------------------------------------------------------------------------
+// The create door, end to end.
+
+function harness(seed: StoredDatasource[] = []) {
+  const records: StoredDatasource[] = seed.map((r) => ({ ...r }));
+  const puts: string[] = [];
+  const config: DatasourceAdminServiceConfig = {
+    probe: async () => ({ ok: true, latencyMs: 1 }),
+    listDatasourceRecords: async () => records.map((r) => ({ ...r })),
+    getDatasourceRecord: async (n) => {
+      const r = records.find((x) => x.name === n);
+      return r ? { ...r } : undefined;
+    },
+    putDatasourceRecord: async (record) => {
+      puts.push(record.name);
+      const i = records.findIndex((r) => r.name === record.name);
+      if (i >= 0) records[i] = { ...record };
+      else records.push({ ...record });
+    },
+    deleteDatasourceRecord: async (n) => {
+      const i = records.findIndex((r) => r.name === n);
+      if (i >= 0) records.splice(i, 1);
+    },
+    writeSecret: async (_input, hint) => `sys_secret://datasource/${hint.name}`,
+    countBoundObjects: async () => 0,
+    listObjectsBoundTo: async () => [],
+  };
+  const service = new DatasourceAdminService(config);
+  const authService = createSessionAuthService();
+  const grantsEngine = createGrantsEngine();
+  const server = new HonoHttpServer(0);
+  const ctx = {
+    getService: (name: string) =>
+      name === 'auth'
+        ? authService
+        : name === 'objectql' || name === 'data'
+          ? grantsEngine
+          : name === 'datasource-admin'
+            ? service
+            : undefined,
+  };
+  registerDatasourceAdminRoutes(server, ctx as never, BASE);
+  const app = server.getRawApp();
+  const call = (path: string, method = 'GET', body?: unknown) =>
+    app.fetch(
+      new Request(`http://local${path}`, {
+        method,
+        headers: { 'content-type': 'application/json', authorization: ENTITLED_CREDENTIAL },
+        ...(body === undefined ? {} : { body: JSON.stringify(body) }),
+      }),
+    );
+  return { call, puts, records };
+}
+
+const draft = (name: string) => ({ name, driver: 'postgres', config: { database: 'analytics' } });
+
+describe('POST /api/v1/datasources — route-shadowed names', () => {
+  it('refuses `drivers` with the 400 DATASOURCE_ADMIN_ERROR naming the segment, and writes nothing', async () => {
+    const { call, puts, records } = harness();
+    const res = await call(ROOT, 'POST', draft('drivers'));
+    expect(res.status).toBe(400);
+    const body = (await res.json()) as { error: { code: string; message: string } };
+    expect(body.error.code).toBe('DATASOURCE_ADMIN_ERROR');
+    expect(body.error.message).toContain("'drivers'");
+    expect(puts).toEqual([]);
+    expect(records).toEqual([]);
+  });
+
+  it('keeps refusing the host-owned `default` the same way', async () => {
+    const { call, puts } = harness();
+    const res = await call(ROOT, 'POST', draft('default'));
+    expect(res.status).toBe(400);
+    const body = (await res.json()) as { error: { code: string; message: string } };
+    expect(body.error.code).toBe('DATASOURCE_ADMIN_ERROR');
+    expect(body.error.message).toContain("'default'");
+    expect(puts).toEqual([]);
+  });
+
+  it('still creates an ordinary name (201) and reads it back by name', async () => {
+    const { call, puts } = harness();
+    const res = await call(ROOT, 'POST', draft('reporting'));
+    expect(res.status).toBe(201);
+    expect(puts).toEqual(['reporting']);
+    const read = await call(`${ROOT}/reporting`);
+    expect(read.status).toBe(200);
+    expect(((await read.json()) as any).data.datasource.name).toBe('reporting');
+  });
+
+  it('still creates `test` — the draft-probe literal shadows no by-name door', async () => {
+    const { call, puts } = harness();
+    const res = await call(ROOT, 'POST', draft('test'));
+    expect(res.status).toBe(201);
+    expect(puts).toEqual(['test']);
+    const read = await call(`${ROOT}/test`);
+    expect(read.status).toBe(200);
+    expect(((await read.json()) as any).data.datasource.name).toBe('test');
+  });
+});
+
+describe('a stored `drivers` row written before the refusal', () => {
+  it('stays listed, patchable and removable — the refusal is at create only', async () => {
+    const { call, records } = harness([{ name: 'drivers', driver: 'postgres', config: { database: 'a' }, origin: 'runtime' }]);
+
+    const list = await call(ROOT);
+    expect(list.status).toBe(200);
+    expect(((await list.json()) as any).data.datasources.map((d: { name: string }) => d.name)).toContain('drivers');
+
+    const patched = await call(`${ROOT}/drivers`, 'PATCH', { label: 'Old drivers' });
+    expect(patched.status).toBe(200);
+    expect(records.find((r) => r.name === 'drivers')?.label).toBe('Old drivers');
+
+    const removed = await call(`${ROOT}/drivers`, 'DELETE');
+    expect(removed.ok).toBe(true);
+    expect(records.some((r) => r.name === 'drivers')).toBe(false);
+  });
+});
@@ -45,6 +45,7 @@ import type { IAuthService, IDataEngine, IHttpServer } from '@objectstack/spec/c
 // The declared envelope is written in ONE place for the whole platform (#3973).
 import { inProcessSessionReadInput, sendOk, sendError } from '@objectstack/types';
 import { DRIVER_CATALOG } from './driver-catalog.js';
+import { DRIVER_CATALOG_SEGMENT } from './datasource-route-reserved-names.js';
 // [#27618] The package's one "no such datasource" refusal: GET answers an
 // unknown name in its words, as every other by-name door does.
 import { datasourceNotFoundError } from './datasource-admin-service.js';
@@ -692,7 +693,7 @@ export function registerDatasourceAdminRoutes(
   // Catalog of connection drivers + their JSON-Schema config (drives the
   // Studio connection form). Static metadata — no service dependency, so it
   // is always available even before any datasource-admin service is wired.
-  server.get(`${root}/drivers`, async (req: any, res: any) => {
+  server.get(`${root}/${DRIVER_CATALOG_SEGMENT}`, async (req: any, res: any) => {
     if (await requireDatasourceAdmin(req, res)) return;
     sendOk(res, { drivers: DRIVER_CATALOG });
   });
 
@@ -43,6 +43,7 @@ import { datasourceConnectivityChanged } from './datasource-connectivity-change.
 import { redactDatasourceConfig, restoreRedactedConfig } from './datasource-config-redaction.js';
 import { planCredentialMigration } from './datasource-credential-migration.js';
 import { borrowedConnectorOf } from './datasource-connector-credential.js';
+import { ROUTE_SHADOWED_DATASOURCE_NAMES } from './datasource-route-reserved-names.js';
 import type {
   IDatasourceAdminService,
   DatasourceDraft,
@@ -1401,6 +1402,17 @@ export class DatasourceAdminService implements IDatasourceAdminService {
         `Datasource name 'default' is reserved for the host's primary datasource. Pick another name.`,
       );
     }
+    // Route-shadowed names (#29164): a literal the admin registrar mounts beside
+    // a same-method `/datasources/:name` route captures that path first, so a
+    // datasource of that name could never be read through its by-name door
+    // (`GET /datasources/drivers` is the driver catalog, not the edit form's
+    // detail read). The list is the one the registrar mounts from.
+    if (ROUTE_SHADOWED_DATASOURCE_NAMES.includes(name)) {
+      throw new Error(
+        `Datasource name '${name}' is reserved: the datasource admin API serves its own route at `
+          + `'/datasources/${name}', so a datasource of that name could never be read by name. Pick another name.`,
+      );
+    }
   }
 
   /**
 
@@ -0,0 +1,38 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * Datasource names the admin route family can never serve by name (#29164).
+ *
+ * `registerDatasourceAdminRoutes` mounts the by-name doors at
+ * `/datasources/:name` and, beside them, literal single-segment routes under
+ * the same root. Where a literal shares a METHOD with a `/:name` route it is
+ * registered first and captures the path: `GET /datasources/drivers` answers
+ * the driver catalog, so a datasource named `drivers` could be created and
+ * listed while its detail read — the load of its edit form — was never
+ * reached. Each such literal is therefore a reserved datasource name, refused
+ * at create the same way the host-owned `default` is.
+ *
+ * A literal that shares no method with a `/:name` route captures no name, and
+ * is not reserved: `POST /datasources/test` (the unsaved-draft probe) sits
+ * beside no `POST /datasources/:name`, so a datasource named `test` is read,
+ * patched, removed and probed (`POST /datasources/test/test`) through its own
+ * doors.
+ *
+ * ONE list for both halves. The registrar mounts each shadowing literal from
+ * the constant below, and `DatasourceAdminService` refuses each name in
+ * {@link ROUTE_SHADOWED_DATASOURCE_NAMES}. The drift pin
+ * (`__tests__/datasource-route-reserved-names.test.ts`) enumerates what the
+ * registrar actually mounts and fails both ways: a literal sibling of a
+ * same-method `/:name` route that is not listed here, and a listed name that
+ * no longer shadows anything.
+ */
+
+/** The driver-catalog literal: `GET /datasources/drivers`, mounted beside `GET /datasources/:name`. */
+export const DRIVER_CATALOG_SEGMENT = 'drivers';
+
+/**
+ * Every literal segment the admin registrar mounts beside a same-method
+ * `/datasources/:name` route — a datasource of one of these names could never
+ * be reached through that by-name door.
+ */
+export const ROUTE_SHADOWED_DATASOURCE_NAMES: readonly string[] = Object.freeze([DRIVER_CATALOG_SEGMENT]);