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fix(cli): harden PR merge path against stale-base dead-ends (empty-diff no-op + conflict escape) #1943

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Merged
gsxdsm merged 1 commit into from
Jul 11, 2026
+126 −12
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fix(cli): harden PR merge path against stale-base dead-ends (empty-diff no-op + conflict escape) #1943

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79 changes: 73 additions & 6 deletions packages/cli/src/commands/__tests__/task-lifecycle.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -668,6 +668,73 @@ describe("processPullRequestMergeTask", () => {
expect(github.getPrMergeStatus).toHaveBeenCalledWith("owner", "repo", 7);
});

it("counts a conflicting stale-base PR against mergeRetries so the stall escape fires", async () => {
const task: MockTask = {
id: "FN-9020",
title: "test",
description: "desc",
column: "in-review",
mergeRetries: 1,
};
const branch = getTaskBranchName(task.id);
const store = makeStore(task);
execMock.mockImplementation(() => "");

const existingPr = { number: 9, url: "https://github.com/x/y/pull/9", status: "open" as const, headBranch: branch, baseBranch: "main" };
const github = {
findPrForBranch: vi.fn(async () => existingPr),
createPr: vi.fn(),
getPrMergeStatus: vi.fn(async () => ({
prInfo: { ...existingPr, mergeable: "conflicting" as const },
reviewDecision: null,
checks: [],
mergeReady: false,
blockingReasons: [],
})),
mergePr: vi.fn(),
};

const result = await processPullRequestMergeTask(store as never, "/repo", task.id, github as never, () => undefined);

expect(result).toBe("waiting");
expect(store.updateTask).toHaveBeenCalledWith(task.id, {
status: "awaiting-pr-checks",
mergeRetries: 2,
});
});

it("does not bump mergeRetries for a non-conflicting not-ready PR", async () => {
const task: MockTask = {
id: "FN-9021",
title: "test",
description: "desc",
column: "in-review",
mergeRetries: 1,
};
const branch = getTaskBranchName(task.id);
const store = makeStore(task);
execMock.mockImplementation(() => "");

const existingPr = { number: 10, url: "https://github.com/x/y/pull/10", status: "open" as const, headBranch: branch, baseBranch: "main" };
const github = {
findPrForBranch: vi.fn(async () => existingPr),
createPr: vi.fn(),
getPrMergeStatus: vi.fn(async () => ({
prInfo: { ...existingPr, mergeable: "unknown" as const },
reviewDecision: null,
checks: [],
mergeReady: false,
blockingReasons: [],
})),
mergePr: vi.fn(),
};

const result = await processPullRequestMergeTask(store as never, "/repo", task.id, github as never, () => undefined);

expect(result).toBe("waiting");
expect(store.updateTask).toHaveBeenCalledWith(task.id, { status: "awaiting-pr-checks" });
});
Comment on lines +671 to +736

@coderabbitai coderabbitai Bot Jul 8, 2026

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📐 Maintainability & Code Quality | 🟠 Major | ⚡ Quick win

Add regression coverage for the shared-branch-group surface.

Both new tests (and the reworked no-delta test) exercise only the per-task PR creation/merge path. The same two behaviors also have a shared-branch-group surface: no-op finalization on "No commits between" (Line 799-812) and the not-ready/conflicting handling (Line 858-861). Please enumerate and assert the invariant on the shared-group surface too — at minimum a shared-group "No commits between" → no-op done case, and (if the gap flagged in task-lifecycle.ts is addressed) a shared-group conflicting case.

As per coding guidelines: "When fixing a bug, regression tests must assert the general invariant across all known surfaces, and bug-fix work must include symptom verification and surface enumeration rather than only the single reproduction."

🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@packages/cli/src/commands/__tests__/task-lifecycle.test.ts` around lines 671
- 736, The current tests cover only the per-task PR path, but the same invariant
must also be verified on the shared-branch-group path. Add regression coverage
in the task lifecycle tests for the shared-group surface by exercising the
shared-group finalization flow that handles the “No commits between” case and
asserting it resolves as a no-op done outcome, and also cover the shared-group
not-ready/conflicting handling if the task-lifecycle logic now routes there. Use
the existing task lifecycle helpers and the shared-group branch-group
entrypoints in task-lifecycle.test.ts to locate the relevant flows.

Source: Coding guidelines


it("skips the push when an existing PR already covers the branch", async () => {
const task: MockTask = {
id: "FN-9002",
Expand Down Expand Up @@ -883,7 +950,7 @@ describe("processPullRequestMergeTask", () => {
expect(github.createPr).toHaveBeenCalledWith(expect.objectContaining({ head: branch }));
});

it("parks no-delta branches instead of retrying into branch push failures", async () => {
it("finalizes no-delta branches as a no-op done instead of failing", async () => {
const task: MockTask = {
id: "FN-9012",
title: "test",
Expand Down Expand Up @@ -913,13 +980,13 @@ describe("processPullRequestMergeTask", () => {

expect(result).toBe("skipped");
expect(store.updateTask).toHaveBeenCalledWith(task.id, {
status: "failed",
error: `No pull request created for ${branch}: the branch has no commits relative to the base branch.`,
status: null,
mergeRetries: 0,
});
expect(store.logEntry).toHaveBeenCalledWith(
expect(store.moveTask).toHaveBeenCalledWith(task.id, "done");
expect(store.updateTask).not.toHaveBeenCalledWith(
task.id,
`No pull request created for ${branch}: the branch has no commits relative to the base branch.`,
expect.stringContaining("No commits between"),
expect.objectContaining({ status: "failed" }),
);
});

Expand Down
59 changes: 53 additions & 6 deletions packages/cli/src/commands/task-lifecycle.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -640,6 +640,40 @@ async function finalizePullRequestMerge(
} as MergeResult);
}

/**
* Finalize a task whose branch has no commits relative to the base branch
* ("No commits between ...") as a terminal no-op DONE, mirroring the engine's
* canonical zero-commits decision (merger-ai.ts `noOpResult` → done, PR #1920).
* Marking it `failed` here left an empty-diff follow-up task pinning the merge
* slot + file leases indefinitely; a no-op branch is not a failure — there was
* simply nothing to merge.
*/
async function finalizeNoOpMergeTask(

@greptile-apps greptile-apps Bot Jul 11, 2026

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P2 Published Fix Has No Changeset

This CLI change affects published @runfusion/fusion behavior by moving empty-diff PR tasks to no-op done and by bounding conflicting PR waits. The repository release rules require a patch changeset for published package fixes, so without one this operator-facing fix can be missed by versioning and release notes.

Context Used: AGENTS.md (source)

store: TaskStore,
cwd: string,
task: TaskDetail,
reason: string,
pool?: WorktreePool,
): Promise<void> {
const branch = task.branch ?? getTaskBranchName(task.id);
await cleanupMergedTaskArtifacts(cwd, task, { pool });
await store.updateTask(task.id, { status: null, mergeRetries: 0 });
const movedTask = await store.moveTask(task.id, "done");
const mergedTask = movedTask ?? (await store.getTask(task.id));
await store.logEntry(task.id, reason, `Branch ${branch} has no commits relative to the base branch; nothing to merge.`);
store.emit("task:merged", {
task: mergedTask,
branch: mergedTask.branch ?? branch,
merged: false,
noOp: true,
ok: true,
reason,
mergeConfirmed: true,
worktreeRemoved: false,
branchDeleted: false,
} as MergeResult);
}

/**
* Result of processing a PR merge task.
* - "waiting": PR exists but not ready to merge (checks pending, reviews needed)
Expand Down Expand Up @@ -774,8 +808,7 @@ export async function processPullRequestMergeTask(
const message = err instanceof Error ? err.message : String(err);
if (message.includes("No commits between")) {
await store.updateBranchGroup(branchGroup.id, { prState: "none", prNumber: null, prUrl: null });
await store.updateTask(task.id, { status: "failed", error: `No pull request created for ${branchGroup.branchName}: no commits relative to ${projectDefaultBranch}.` });
await store.logEntry(task.id, "No group pull request created", message);
await finalizeNoOpMergeTask(store, cwd, task, "No group pull request created (no commits vs base) — finalizing as no-op", pool);

@greptile-apps greptile-apps Bot Jul 11, 2026

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P1 Group No-Op Leaves Members Open

When a shared branch-group PR has no commits relative to the base, this branch clears the group PR state but finalizes only the current task. Sibling members can remain in in-review with the shared group reset to prState: "none", so later lifecycle passes can recreate or split the group flow instead of completing the whole no-op group together.

Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!

return "skipped";
}
throw err;
Expand Down Expand Up @@ -878,9 +911,7 @@ export async function processPullRequestMergeTask(
} catch (err: unknown) {
const message = err instanceof Error ? err.message : String(err);
if (message.includes("No commits between")) {
const error = `No pull request created for ${branch}: the branch has no commits relative to the base branch.`;
await store.updateTask(task.id, { status: "failed", error });
await store.logEntry(task.id, error, message);
await finalizeNoOpMergeTask(store, cwd, task, "No pull request created (no commits vs base) — finalizing as no-op", pool);
return "skipped";
}
throw err;
Expand Down Expand Up @@ -924,7 +955,23 @@ export async function processPullRequestMergeTask(

if (!mergeStatus.mergeReady) {
if (mergeStatus.prInfo.status === "open") {
await store.updateTask(task.id, { status: "awaiting-pr-checks" });
// A stale-base PR that GitHub reports as CONFLICTING never becomes
// mergeable on its own — nothing in the PR path rebases the head branch —
// so an unbounded `awaiting-pr-checks` wait pins the merge slot + file
// leases forever (FN-485). Count each conflicting poll against
// `mergeRetries` so the existing `getInReviewStallReason`
// "merge-retries-exhausted" escape disposes the task after
// `maxAutoMergeRetries` cycles. Pending/behind PRs still wait indefinitely
// (checks legitimately run; "behind" is resolved by the pre-merge rebase).
// ponytail: bounded escape via the existing stall counter, not an in-path
// rebase. Upgrade path: rebase the head branch onto base + force-push here
// before giving up, then reset mergeRetries.
await store.updateTask(task.id, {
status: "awaiting-pr-checks",
...(mergeStatus.prInfo.mergeable === "conflicting"
? { mergeRetries: (task.mergeRetries ?? 0) + 1 }
: {}),
});
} else {
await store.updateTask(task.id, { status: null });
}
Expand Down
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