fix: reconcile PR merge race

.changeset/reconcile-pr-merge-race.md

@@ -0,0 +1,5 @@
+---
+"@runfusion/fusion": patch
+---
+
+Reconcile pull-request merge tasks when GitHub reports the PR merged after a merge command failure.

packages/cli/src/commands/__tests__/task-lifecycle.test.ts

@@ -502,6 +502,80 @@ describe("processPullRequestMergeTask", () => {
     expect(store.moveTask).toHaveBeenCalledWith("FN-9004", "done");
   });
 
+  it("reconciles to done when PR merges after readiness check but before merge command completes", async () => {
+    const task: MockTask = {
+      id: "FN-9104",
+      title: "test",
+      description: "desc",
+      column: "in-review",
+      worktree: "/tmp/worktree-fn-9104",
+      prInfo: {
+        number: 124,
+        url: "https://github.com/x/y/pull/124",
+        status: "open",
+        headBranch: "fusion/fn-9104",
+        baseBranch: "main",
+      },
+    };
+    const store = makeStore(task);
+    execMock.mockImplementation(() => "");
+
+    const openPr = {
+      number: 124,
+      url: "https://github.com/x/y/pull/124",
+      status: "open" as const,
+      headBranch: "fusion/fn-9104",
+      baseBranch: "main",
+    };
+    const mergedPr = {
+      ...openPr,
+      status: "merged" as const,
+    };
+    const github = {
+      findPrForBranch: vi.fn(),
+      createPr: vi.fn(),
+      getPrMergeStatus: vi
+        .fn()
+        .mockResolvedValueOnce({
+          prInfo: openPr,
+          reviewDecision: "APPROVED",
+          checks: [],
+          mergeReady: true,
+          blockingReasons: [],
+        })
+        .mockResolvedValueOnce({
+          prInfo: mergedPr,
+          reviewDecision: "APPROVED",
+          checks: [],
+          mergeReady: true,
+          blockingReasons: [],
+        }),
+      mergePr: vi.fn(async () => {
+        throw new Error("Pull request is not mergeable: the merge commit cannot be cleanly created");
+      }),
+    };
+
+    const result = await processPullRequestMergeTask(
+      store as never,
+      "/repo",
+      task.id,
+      github as never,
+      () => undefined,
+    );
+
+    expect(result).toBe("merged");
+    expect(github.mergePr).toHaveBeenCalledWith({ number: 124, method: "squash" });
+    expect(github.getPrMergeStatus).toHaveBeenCalledTimes(2);
+    expect(store.updatePrInfo).toHaveBeenLastCalledWith("FN-9104", expect.objectContaining({ status: "merged" }));
+    expect(store.updateTask).toHaveBeenCalledWith("FN-9104", { status: null, mergeRetries: 0 });
+    expect(store.moveTask).toHaveBeenCalledWith("FN-9104", "done");
+    expect(store.logEntry).toHaveBeenCalledWith(
+      "FN-9104",
+      "Pull request already merged after merge command failed; reconciled task state from GitHub",
+      "PR #124: https://github.com/x/y/pull/124",
+    );
+  });
+
   it("preserves PR number/url through create, refresh, and merge completion", async () => {
     const task: MockTask = {
       id: "FN-9103",

packages/cli/src/commands/task-lifecycle.ts

@@ -175,11 +175,12 @@ async function finalizePullRequestMerge(
   cwd: string,
   task: TaskDetail,
   prInfo: PrInfo,
+  message = "Pull request merged",
 ): Promise<void> {
   await cleanupMergedTaskArtifacts(cwd, task);
   await store.updateTask(task.id, { status: null, mergeRetries: 0 });
   await store.moveTask(task.id, "done");
-  await store.logEntry(task.id, "Pull request merged", `PR #${prInfo.number}: ${prInfo.url}`);
+  await store.logEntry(task.id, message, `PR #${prInfo.number}: ${prInfo.url}`);
 }
 
 /**
@@ -316,7 +317,36 @@ export async function processPullRequestMergeTask(
     return "waiting";
   }
   await store.updateTask(task.id, { status: "merging-pr" });
-  const mergedPr = await github.mergePr({ number: prInfo.number, method: "squash" });
+  let mergedPr: PrInfo;
+  try {
+    mergedPr = await github.mergePr({ number: prInfo.number, method: "squash" });
+  } catch (err: unknown) {
+    let refreshedStatus: Awaited<ReturnType<GitHubOperations["getPrMergeStatus"]>>;
+    try {
+      refreshedStatus = await github.getPrMergeStatus(mergeTarget.branch, branch, prInfo.number);
+    } catch {
+      throw err;
+    }
+    const refreshedAfterFailure: PrInfo = {
+      ...prInfo,
+      ...refreshedStatus.prInfo,
+      lastCheckedAt: new Date().toISOString(),
+    };
+    await store.updatePrInfo(task.id, refreshedAfterFailure);
+
+    if (refreshedAfterFailure.status === "merged") {
+      await finalizePullRequestMerge(
+        store,
+        cwd,
+        task,
+        refreshedAfterFailure,
+        "Pull request already merged after merge command failed; reconciled task state from GitHub",
+      );
+      return "merged";
+    }
+
+    throw err;
+  }
   await store.updatePrInfo(task.id, { ...mergedPr, lastCheckedAt: new Date().toISOString() });
   await finalizePullRequestMerge(store, cwd, task, mergedPr);
   return "merged";