diff --git a/.changeset/calm-queens-brush.md b/.changeset/calm-queens-brush.md
new file mode 100644
index 0000000000..0618e4c459
--- /dev/null
+++ b/.changeset/calm-queens-brush.md
@@ -0,0 +1,5 @@
+---
+"@workflow/core": patch
+---
+
+test(core): cover cancel run spec version
diff --git a/packages/core/src/runtime/runs.test.ts b/packages/core/src/runtime/runs.test.ts
index 2c983e21c7..2928b72175 100644
--- a/packages/core/src/runtime/runs.test.ts
+++ b/packages/core/src/runtime/runs.test.ts
@@ -19,7 +19,7 @@ import {
   hydrateStepReturnValue,
 } from '../serialization.js';
 import { Run } from './run.js';
-import { wakeUpRun } from './runs.js';
+import { cancelRun, wakeUpRun } from './runs.js';
 import { setWorld } from './world.js';
 
 function createMockWorld(
@@ -108,6 +108,41 @@ describe('wakeUpRun', () => {
   });
 });
 
+describe('cancelRun', () => {
+  it('should create a run_cancelled event with the run specVersion', async () => {
+    const world = createMockWorld({ run: { specVersion: 2 } });
+
+    await cancelRun(world, 'wrun_123');
+
+    expect(world.runs.get).toHaveBeenCalledWith('wrun_123', {
+      resolveData: 'none',
+    });
+    expect(world.events.create).toHaveBeenCalledWith(
+      'wrun_123',
+      {
+        eventType: 'run_cancelled',
+        specVersion: 2,
+      },
+      { v1Compat: false }
+    );
+  });
+
+  it('should use the legacy cancel endpoint for legacy runs', async () => {
+    const world = createMockWorld({ run: { specVersion: undefined } });
+
+    await cancelRun(world, 'wrun_123');
+
+    expect(world.events.create).toHaveBeenCalledWith(
+      'wrun_123',
+      {
+        eventType: 'run_cancelled',
+        specVersion: 1,
+      },
+      { v1Compat: true }
+    );
+  });
+});
+
 describe('Run.exists', () => {
   afterEach(() => {
     setWorld(undefined as unknown as World);
diff --git a/packages/world-postgres/src/queue.test.ts b/packages/world-postgres/src/queue.test.ts
index dd2122ecde..2348401c6e 100644
--- a/packages/world-postgres/src/queue.test.ts
+++ b/packages/world-postgres/src/queue.test.ts
@@ -2,21 +2,19 @@ import { createServer, type Server } from 'node:http';
 import { JsonTransport } from '@vercel/queue';
 import { getWorkflowPort } from '@workflow/utils/get-port';
 import { MessageId, type QueuePayload } from '@workflow/world';
+import { createLocalWorld } from '@workflow/world-local';
 import { makeWorkerUtils, run, type WorkerUtils } from 'graphile-worker';
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
-import { createLocalWorld } from '@workflow/world-local';
 import { stepEntrypoint } from '../../core/dist/runtime/step-handler.js';
-import { createQueue } from './queue.js';
 import { MessageData } from './message.js';
+import { createQueue } from './queue.js';
 
 const transport = new JsonTransport();
 const createdQueues: Array<ReturnType<typeof createQueue>> = [];
 const createdServers: Server[] = [];
 
 vi.mock('graphile-worker', () => ({
-  Logger: class Logger {
-    constructor(_: unknown) {}
-  },
+  Logger: class Logger {},
   makeWorkerUtils: vi.fn(),
   run: vi.fn(),
 }));
@@ -46,8 +44,13 @@ describe('postgres queue http execution', () => {
   const wrappedHandler = vi.fn(async () => Response.json({ ok: true }));
   const localWorldClose = vi.fn();
   const createQueueHandler = vi.fn(() => wrappedHandler);
+  const advisoryClient = {
+    query: vi.fn(),
+    release: vi.fn(),
+  };
   const pool = {
     query: vi.fn(async () => ({ rows: [{ exists: false }] })),
+    connect: vi.fn(async () => advisoryClient),
   } as any;
 
   beforeEach(() => {
@@ -62,6 +65,38 @@ describe('postgres queue http execution', () => {
     } as any);
   });
 
+  it('serializes graphile migrations with an advisory lock', async () => {
+    const queue = buildQueue({ connectionString: 'postgres://test' }, pool);
+
+    await queue.start();
+
+    expect(pool.connect).toHaveBeenCalled();
+    expect(advisoryClient.query).toHaveBeenCalledWith(
+      'SELECT pg_advisory_lock(hashtext($1))',
+      ['workflow_graphile_worker_migrate']
+    );
+    expect(advisoryClient.query).toHaveBeenCalledWith(
+      'SELECT pg_advisory_unlock(hashtext($1))',
+      ['workflow_graphile_worker_migrate']
+    );
+    expect(advisoryClient.release).toHaveBeenCalledOnce();
+
+    const lockOrder = advisoryClient.query.mock.invocationCallOrder[0];
+    const migrateOrder = vi.mocked(workerUtilsMock.migrate).mock
+      .invocationCallOrder[0];
+    const unlockOrder =
+      advisoryClient.query.mock.invocationCallOrder[
+        advisoryClient.query.mock.calls.findIndex(
+          ([query]) => query === 'SELECT pg_advisory_unlock(hashtext($1))'
+        )
+      ];
+    const releaseOrder = advisoryClient.release.mock.invocationCallOrder[0];
+
+    expect(lockOrder).toBeLessThan(migrateOrder);
+    expect(migrateOrder).toBeLessThan(unlockOrder);
+    expect(unlockOrder).toBeLessThan(releaseOrder);
+  });
+
   afterEach(async () => {
     await Promise.all(createdQueues.splice(0).map((queue) => queue.close()));
     await Promise.all(
diff --git a/packages/world-postgres/src/queue.ts b/packages/world-postgres/src/queue.ts
index 83624cc6b4..a79b59fcc7 100644
--- a/packages/world-postgres/src/queue.ts
+++ b/packages/world-postgres/src/queue.ts
@@ -17,7 +17,7 @@ import {
   run,
   type WorkerUtils,
 } from 'graphile-worker';
-import type { Pool } from 'pg';
+import type { Pool, PoolClient } from 'pg';
 import { monotonicFactory } from 'ulid';
 import { z } from 'zod/v4';
 import type { PostgresWorldConfig } from './config.js';
@@ -43,6 +43,7 @@ function createGraphileLogger() {
 
 const graphileLogger = createGraphileLogger();
 const COMPLETED_IDEMPOTENCY_CACHE_LIMIT = 10_000;
+const GRAPHILE_MIGRATION_LOCK_KEY = 'workflow_graphile_worker_migrate';
 const GraphileHelpers = z.object({
   job: z.object({
     attempts: z.number().int().positive(),
@@ -329,16 +330,38 @@ export function createQueue(
     }
   }
 
+  async function withGraphileMigrationLock<T>(
+    fn: () => Promise<T>
+  ): Promise<T> {
+    const client: PoolClient = await pool.connect();
+    try {
+      await client.query('SELECT pg_advisory_lock(hashtext($1))', [
+        GRAPHILE_MIGRATION_LOCK_KEY,
+      ]);
+      try {
+        return await fn();
+      } finally {
+        await client.query('SELECT pg_advisory_unlock(hashtext($1))', [
+          GRAPHILE_MIGRATION_LOCK_KEY,
+        ]);
+      }
+    } finally {
+      client.release();
+    }
+  }
+
   async function start(): Promise<void> {
     if (!startPromise) {
       startPromise = (async () => {
         try {
-          workerUtils = await makeWorkerUtils({
-            pgPool: pool,
-            logger: graphileLogger,
+          await withGraphileMigrationLock(async () => {
+            workerUtils = await makeWorkerUtils({
+              pgPool: pool,
+              logger: graphileLogger,
+            });
+            await workerUtils.migrate();
+            await migratePgBossJobs(workerUtils);
           });
-          await workerUtils.migrate();
-          await migratePgBossJobs(workerUtils);
           await setupListeners();
         } catch (err) {
           startPromise = null;