diff --git a/examples/notion-essay-pr/notion-essay-pr.smoke.test.ts b/examples/notion-essay-pr/notion-essay-pr.smoke.test.ts
index 60b72c8a..b0bb8146 100644
--- a/examples/notion-essay-pr/notion-essay-pr.smoke.test.ts
+++ b/examples/notion-essay-pr/notion-essay-pr.smoke.test.ts
@@ -143,7 +143,8 @@ class MockNotionEssayRuntime {
         createPullRequest: async (args) => {
           this.githubPullRequests.push(args);
           return { number: 17, url: 'https://github.com/AgentWorkforce/proactive-agents/pull/17' };
-        }
+        },
+        mergePullRequest: async () => ({ merged: true, sha: 'merge-sha' })
       }
     };
   }
diff --git a/packages/deploy/test/e2e/notion-essay-pr.smoke.test.ts b/packages/deploy/test/e2e/notion-essay-pr.smoke.test.ts
index 3906870d..7bb669aa 100644
--- a/packages/deploy/test/e2e/notion-essay-pr.smoke.test.ts
+++ b/packages/deploy/test/e2e/notion-essay-pr.smoke.test.ts
@@ -156,7 +156,8 @@ class MockNotionEssayRuntime {
         createPullRequest: async (args) => {
           this.githubPullRequests.push(args);
           return { number: 17, url: 'https://github.com/AgentWorkforce/proactive-agents/pull/17' };
-        }
+        },
+        mergePullRequest: async () => ({ merged: true, sha: 'merge-sha' })
       }
     };
   }
diff --git a/packages/runtime/src/clients/github.test.ts b/packages/runtime/src/clients/github.test.ts
index f125edab..ff5a7b05 100644
--- a/packages/runtime/src/clients/github.test.ts
+++ b/packages/runtime/src/clients/github.test.ts
@@ -82,6 +82,150 @@ test('github.createPullRequest writes a draft pull request file under pulls/', a
   }
 });
 
+test('github.mergePullRequest writes a merge draft under pulls/<n>/merge.json', async () => {
+  const root = await tempMount();
+  try {
+    const client = createGithubClient({ relayfileMountRoot: root, writebackTimeoutMs: 0 });
+    const result = await client.mergePullRequest({
+      owner: 'o',
+      repo: 'r',
+      number: 42,
+      method: 'rebase',
+      commitTitle: 'Merge PR #42',
+      commitMessage: 'Ship the feature.',
+      sha: 'reviewed-head'
+    });
+
+    assert.deepEqual(result, { merged: false });
+    const mergePath = path.join(root, 'github/repos/o/r/pulls/42/merge.json');
+    assert.deepEqual(JSON.parse(await readFile(mergePath, 'utf8')), {
+      merge_method: 'rebase',
+      commit_title: 'Merge PR #42',
+      commit_message: 'Ship the feature.',
+      sha: 'reviewed-head'
+    });
+  } finally {
+    await rm(root, { recursive: true, force: true });
+  }
+});
+
+test('github.mergePullRequest preserves empty commit metadata and omits the merge method by default', async () => {
+  const root = await tempMount();
+  try {
+    const client = createGithubClient({ relayfileMountRoot: root, writebackTimeoutMs: 0 });
+    const result = await client.mergePullRequest({
+      owner: 'o',
+      repo: 'r',
+      number: 42,
+      commitTitle: '',
+      commitMessage: ''
+    });
+
+    assert.deepEqual(result, { merged: false });
+    const mergePath = path.join(root, 'github/repos/o/r/pulls/42/merge.json');
+    assert.deepEqual(JSON.parse(await readFile(mergePath, 'utf8')), {
+      commit_title: '',
+      commit_message: ''
+    });
+  } finally {
+    await rm(root, { recursive: true, force: true });
+  }
+});
+
+test('github.mergePullRequest waits for a GitHub merge receipt', async () => {
+  const root = await tempMount();
+  try {
+    const client = createGithubClient({ relayfileMountRoot: root, writebackTimeoutMs: 1_000, writebackPollMs: 10 });
+    const mergePath = path.join(root, 'github/repos/o/r/pulls/42/merge.json');
+    const resultPromise = client.mergePullRequest({
+      owner: 'o',
+      repo: 'r',
+      number: 42,
+      method: 'squash',
+      sha: 'reviewed-head'
+    });
+
+    const receiptWritePromise = (async () => {
+      await new Promise((resolve) => setTimeout(resolve, 25));
+      await writeFile(mergePath, `${JSON.stringify({ merged: true, sha: 'merge-sha' })}\n`, 'utf8');
+    })();
+
+    const [result] = await Promise.all([resultPromise, receiptWritePromise]);
+    assert.deepEqual(result, { merged: true, sha: 'merge-sha' });
+  } finally {
+    await rm(root, { recursive: true, force: true });
+  }
+});
+
+test('github.mergePullRequest accepts string merge receipts', async () => {
+  const root = await tempMount();
+  try {
+    const client = createGithubClient({ relayfileMountRoot: root, writebackTimeoutMs: 1_000, writebackPollMs: 10 });
+    const mergePath = path.join(root, 'github/repos/o/r/pulls/42/merge.json');
+    const resultPromise = client.mergePullRequest({
+      owner: 'o',
+      repo: 'r',
+      number: 42
+    });
+
+    const receiptWritePromise = (async () => {
+      await new Promise((resolve) => setTimeout(resolve, 25));
+      await writeFile(mergePath, `${JSON.stringify({ merged: 'true', sha: 'merge-sha' })}\n`, 'utf8');
+    })();
+
+    const [result] = await Promise.all([resultPromise, receiptWritePromise]);
+    assert.deepEqual(result, { merged: true, sha: 'merge-sha' });
+  } finally {
+    await rm(root, { recursive: true, force: true });
+  }
+});
+
+test('github.mergePullRequest respects explicit failed merge receipts with sha values', async () => {
+  const root = await tempMount();
+  try {
+    const client = createGithubClient({ relayfileMountRoot: root, writebackTimeoutMs: 1_000, writebackPollMs: 10 });
+    const mergePath = path.join(root, 'github/repos/o/r/pulls/42/merge.json');
+    const resultPromise = client.mergePullRequest({
+      owner: 'o',
+      repo: 'r',
+      number: 42
+    });
+
+    const receiptWritePromise = (async () => {
+      await new Promise((resolve) => setTimeout(resolve, 25));
+      await writeFile(mergePath, `${JSON.stringify({ merged: false, sha: 'head-sha' })}\n`, 'utf8');
+    })();
+
+    const [result] = await Promise.all([resultPromise, receiptWritePromise]);
+    assert.deepEqual(result, { merged: false, sha: 'head-sha' });
+  } finally {
+    await rm(root, { recursive: true, force: true });
+  }
+});
+
+test('github.mergePullRequest treats identifier-only receipts as merged', async () => {
+  const root = await tempMount();
+  try {
+    const client = createGithubClient({ relayfileMountRoot: root, writebackTimeoutMs: 1_000, writebackPollMs: 10 });
+    const mergePath = path.join(root, 'github/repos/o/r/pulls/42/merge.json');
+    const resultPromise = client.mergePullRequest({
+      owner: 'o',
+      repo: 'r',
+      number: 42
+    });
+
+    const receiptWritePromise = (async () => {
+      await new Promise((resolve) => setTimeout(resolve, 25));
+      await writeFile(mergePath, `${JSON.stringify({ id: 'merge-sha' })}\n`, 'utf8');
+    })();
+
+    const [result] = await Promise.all([resultPromise, receiptWritePromise]);
+    assert.deepEqual(result, { merged: true, sha: 'merge-sha' });
+  } finally {
+    await rm(root, { recursive: true, force: true });
+  }
+});
+
 test('github.upsertIssue updates an existing flat issue match', async () => {
   const root = await tempMount();
   try {
diff --git a/packages/runtime/src/clients/github.ts b/packages/runtime/src/clients/github.ts
index d44cc731..85192ac7 100644
--- a/packages/runtime/src/clients/github.ts
+++ b/packages/runtime/src/clients/github.ts
@@ -39,6 +39,15 @@ export interface GithubClient {
     base: string;
     files?: Record<string, string>;
   }): Promise<{ number: number; url: string }>;
+  mergePullRequest(args: {
+    owner: string;
+    repo: string;
+    number: number;
+    method?: 'merge' | 'squash' | 'rebase';
+    commitTitle?: string;
+    commitMessage?: string;
+    sha?: string;
+  }): Promise<{ merged: boolean; sha?: string }>;
   upsertIssue(args: {
     owner: string;
     repo: string;
@@ -157,6 +166,34 @@ export function createGithubClient(opts: IntegrationClientOptions): GithubClient
       return { number: Number.isFinite(number) ? number : 0, url: result.receipt?.url ?? result.path };
     },
 
+    async mergePullRequest(args) {
+      const result = await writeJsonFile(
+        opts,
+        'github',
+        'mergePullRequest',
+        `${repoRoot(args.owner, args.repo)}/pulls/${encodeSegment(args.number)}/merge.json`,
+        {
+          ...(args.method !== undefined ? { merge_method: args.method } : {}),
+          ...(args.commitTitle !== undefined ? { commit_title: args.commitTitle } : {}),
+          ...(args.commitMessage !== undefined ? { commit_message: args.commitMessage } : {}),
+          ...(args.sha !== undefined ? { sha: args.sha } : {})
+        }
+      );
+      const sha =
+        typeof result.receipt?.sha === 'string'
+          ? result.receipt.sha
+          : typeof result.receipt?.id === 'string'
+            ? result.receipt.id
+            : typeof result.receipt?.externalId === 'string'
+              ? result.receipt.externalId
+              : undefined;
+      const receiptMerged = result.receipt?.merged;
+      return {
+        merged: receiptMerged === true || receiptMerged === 'true' || (receiptMerged === undefined && Boolean(sha)),
+        ...(sha ? { sha } : {})
+      };
+    },
+
     async upsertIssue(args) {
       const issueDir = `${repoRoot(args.owner, args.repo)}/issues`;
       const flatIssues = await listJsonFiles<GithubIssueFile>(opts, 'github', 'upsertIssue.find.flat', issueDir);
diff --git a/packages/runtime/src/clients/request.ts b/packages/runtime/src/clients/request.ts
index 45acaa5a..295aa1c1 100644
--- a/packages/runtime/src/clients/request.ts
+++ b/packages/runtime/src/clients/request.ts
@@ -61,6 +61,9 @@ export interface WritebackReceipt {
   url?: string;
   id?: string;
   identifier?: string;
+  externalId?: string;
+  merged?: boolean | string;
+  sha?: string;
   [key: string]: unknown;
 }
 
@@ -237,7 +240,10 @@ async function waitForReceipt(
       isRecord(parsed) &&
       (typeof parsed.created === 'string' ||
         typeof parsed.path === 'string' ||
-        typeof parsed.id === 'string')
+        typeof parsed.id === 'string' ||
+        typeof parsed.externalId === 'string' ||
+        typeof parsed.merged === 'boolean' ||
+        typeof parsed.merged === 'string')
     ) {
       return parsed as WritebackReceipt;
     }