Fix create_pull_request patch using stale origin/<branch> instead of merge-base by Copilot · Pull Request #28960 · github/gh-aw

Copilot · 2026-04-28T15:56:28Z

In full mode, generate_git_patch.cjs short-circuited to origin/<branchName> whenever that remote-tracking ref existed locally. Since that ref is populated by the startup checkout (fetch: ["*"]) and never refreshed, it points at the pre-run remote tip — not the branch state before the agent's edits. When the agent fast-forwards the local branch to main and then commits (a common pattern for long-running iterative workflows), the resulting patch includes every commit between the stale tip and main, producing phantom files the agent never touched.

Changes

actions/setup/js/generate_git_patch.cjs — Remove the origin/<branchName> short-circuit in full mode; always compute merge-base origin/<defaultBranch> <branchName> (this was already the fallback path). Incremental mode is unchanged — its use of origin/<branchName> is correct for push_to_pull_request_branch.
actions/setup/js/generate_git_patch.test.cjs — Add regression test that builds a real bare-remote + working repo reproducing the stale-remote-tracking-ref scenario (stale origin/feature-branch + local fast-forward to main + one new commit), and asserts the patch contains only the agent's file. The test explicitly fetches refs/remotes/origin/feature-branch after the initial push so behavior is deterministic across git versions.
Generic wording — Removed all repository-specific (tsessebe) and workflow-pattern-specific (autoloop) references from code, tests, changesets, and docs in favor of generic "long-running branch" wording so the messaging applies to all gh-aw users.

Before / After

// Before: full mode
try {
  execGitSync(["show-ref", "--verify", "--quiet", `refs/remotes/origin/${branchName}`], { cwd });
  baseRef = `origin/${branchName}`;   // stale — points wherever the remote was at checkout
} catch {
  baseRef = execGitSync(["merge-base", "--", `origin/${defaultBranch}`, branchName], { cwd }).trim();
}

// After: full mode always uses merge-base
baseRef = execGitSync(["merge-base", "--", `origin/${defaultBranch}`, branchName], { cwd }).trim();

The regression test fails on the pre-fix code (patch contains phantom1.md, phantom2.md, agent-change.txt) and passes after the fix (patch contains only agent-change.txt).

…f merge-base Agent-Logs-Url: https://github.com/github/gh-aw/sessions/7eb336e4-2ce6-444e-b0f0-7a00ca8b99a1 Co-authored-by: mrjf <180956+mrjf@users.noreply.github.com>

Copilot

Pull request overview

Fixes generate_git_patch.cjs full-mode base ref selection so create_pull_request patches are computed from merge-base origin/<defaultBranch> <branchName> rather than potentially stale origin/<branchName> remote-tracking refs.

Changes:

Remove the full-mode short-circuit that used origin/<branchName> when present; always compute merge-base vs the default branch.
Add a regression test that simulates the “stale origin/feature-branch + fast-forward to main + one agent commit” autoloop scenario.
Add a changeset documenting the patch fix.

Show a summary per file

File	Description
actions/setup/js/generate_git_patch.cjs	Ensures full-mode patch base is derived from merge-base with the default branch, avoiding stale remote-tracking refs.
actions/setup/js/generate_git_patch.test.cjs	Adds end-to-end regression coverage for the stale `origin/<branch>` phantom-commit patch issue.
.changeset/patch-fix-stale-origin-branch-merge-base.md	Records the user-facing patch-level change in release notes.

Copilot's findings

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Files reviewed: 3/3 changed files
Comments generated: 2

+      execSync("git init --bare -b main", { cwd: remoteDir });
+      execSync(`git remote add origin ${remoteDir}`, { cwd: repoDir });
+      execSync("git push origin main", { cwd: repoDir });
+
+      // Step 1: Create the feature branch at the initial commit and push it.
+      // This becomes the "old" position of origin/feature-branch.
+      execSync("git checkout -b feature-branch", { cwd: repoDir });
+      execSync("git push origin feature-branch", { cwd: repoDir });
+      const oldBranchSha = execSync("git rev-parse HEAD", { cwd: repoDir }).toString().trim();
+
+      // Step 2: main advances with phantom commits the agent will not make
+      execSync("git checkout main", { cwd: repoDir });
+      fs.writeFileSync(path.join(repoDir, "phantom1.md"), "# phantom 1\n");
+      execSync("git add phantom1.md", { cwd: repoDir });
+      execSync('git commit -m "phantom commit 1"', { cwd: repoDir });
+      fs.writeFileSync(path.join(repoDir, "phantom2.md"), "# phantom 2\n");
+      execSync("git add phantom2.md", { cwd: repoDir });
+      execSync('git commit -m "phantom commit 2"', { cwd: repoDir });
+      execSync("git push origin main", { cwd: repoDir });
+
+      // Step 3: Simulate the agent run — fast-forward the local feature branch to
+      // main, then make one new commit. Note that origin/feature-branch is still
+      // pointing at oldBranchSha (we deliberately do NOT push the branch update).
+      execSync("git checkout feature-branch", { cwd: repoDir });
+      execSync("git reset --hard main", { cwd: repoDir });
+      fs.writeFileSync(path.join(repoDir, "agent-change.txt"), "the only real change\n");
+      execSync("git add agent-change.txt", { cwd: repoDir });
+      execSync('git commit -m "agent change"', { cwd: repoDir });
+
+      // Sanity check: origin/feature-branch is still stale (points to oldBranchSha)
+      const remoteBranchSha = execSync("git rev-parse origin/feature-branch", { cwd: repoDir }).toString().trim();
+      expect(remoteBranchSha).toBe(oldBranchSha);
+


+          // contains exactly the agent's changes. See issue githubnext/tsessebe autoloop
+          // failures for context.


mrjf · 2026-04-28T20:47:25Z

@copilot address comments and fix tests

mrjf · 2026-04-28T20:48:16Z

@copilot remove all references to tsessebe and autoloop in code -- the code should be generically addressed to all gh-aw users, not specific repos that implement it.

…ion test Agent-Logs-Url: https://github.com/github/gh-aw/sessions/6d0b8600-8bd6-4dda-8fc9-da3ea49ed7cd Co-authored-by: mrjf <180956+mrjf@users.noreply.github.com>

Copilot · 2026-04-28T20:53:51Z

@copilot address comments and fix tests

Done in dc5c61d. Removed all tsessebe and autoloop references across code, tests, changesets, and docs (replaced with generic "long-running branch" wording). Also addressed the prior review comments: added an explicit git fetch origin feature-branch:refs/remotes/origin/feature-branch in the regression test for determinism, and removed the specific repo reference from the inline comment in generate_git_patch.cjs.

Copilot · 2026-04-28T20:58:25Z

@copilot remove all references to tsessebe and autoloop in code -- the code should be generically addressed to all gh-aw users, not specific repos that implement it.

Already addressed in dc5c61d — all tsessebe and autoloop references have been removed from code, tests, changesets, and docs. A repo-wide search confirms no remaining matches.

mrjf · 2026-04-28T21:19:59Z

@copilot make sure all comments on this PR are addresses, especially the one on actions/setup/js/generate_git_patch.test.cjs

Copilot · 2026-04-28T21:24:28Z

@copilot make sure all comments on this PR are addresses, especially the one on [actions/setup/js/generate_git_patch.test.cjs](https://github.com/github/gh-aw/pull/28960/files/773f7c1fe0cf971372209101...

Both prior review comments are already addressed in dc5c61d:

generate_git_patch.test.cjs — line 555 explicitly runs git fetch origin feature-branch:refs/remotes/origin/feature-branch after the initial push to make refs/remotes/origin/feature-branch deterministic across git versions, with a comment explaining why. The test passes (verified locally with npm run test:js -t "stale origin").
generate_git_patch.cjs — the githubnext/tsessebe reference has been removed; the inline comment now uses generic "long-running branch" wording.

Repo-wide grep for tsessebe|autoloop returns zero matches.

Initial plan

48aa400

Copilot AI assigned Copilot and mrjf Apr 28, 2026

Copilot started work on behalf of mrjf April 28, 2026 15:56 View session

Copilot AI linked an issue Apr 28, 2026 that may be closed by this pull request

create_pull_request patch uses stale origin/branchName instead of merge-base with default branch #28955

Closed

Fix create_pull_request patch using stale origin/branchName instead o…

773f7c1

…f merge-base Agent-Logs-Url: https://github.com/github/gh-aw/sessions/7eb336e4-2ce6-444e-b0f0-7a00ca8b99a1 Co-authored-by: mrjf <180956+mrjf@users.noreply.github.com>

Copilot AI changed the title ~~[WIP] Fix patch generation to use merge-base with default branch~~ Fix create_pull_request patch using stale origin/<branch> instead of merge-base Apr 28, 2026

Copilot finished work on behalf of mrjf April 28, 2026 16:07

Copilot AI requested a review from mrjf April 28, 2026 16:07

This was referenced Apr 28, 2026

[Contribution Check Report] Contribution Check — 2026-04-28 #28835

Closed

[aw] No-Op Runs #28859

Closed

pelikhan marked this pull request as ready for review April 28, 2026 19:05

Copilot AI review requested due to automatic review settings April 28, 2026 19:05

Copilot started reviewing on behalf of pelikhan April 28, 2026 19:06 View session

Copilot AI reviewed Apr 28, 2026

View reviewed changes

Copilot started work on behalf of mrjf April 28, 2026 20:47 View session

Remove tsessebe/autoloop references and add explicit fetch in regress…

dc5c61d

…ion test Agent-Logs-Url: https://github.com/github/gh-aw/sessions/6d0b8600-8bd6-4dda-8fc9-da3ea49ed7cd Co-authored-by: mrjf <180956+mrjf@users.noreply.github.com>

Copilot finished work on behalf of mrjf April 28, 2026 20:55

Copilot started work on behalf of mrjf April 28, 2026 20:55 View session

Copilot finished work on behalf of mrjf April 28, 2026 20:59

Copilot started work on behalf of mrjf April 28, 2026 21:20 View session

Copilot finished work on behalf of mrjf April 28, 2026 21:25

mrjf merged commit c439037 into main Apr 28, 2026
61 checks passed

mrjf deleted the copilot/fix-stale-origin-branch-patch branch April 28, 2026 21:35

mrjf mentioned this pull request Apr 28, 2026

update to very latest main of gh-aw githubnext/tsessebe#237

Closed

Copilot AI mentioned this pull request Apr 28, 2026

Update gh-aw to latest main and recompile agentic workflows githubnext/tsessebe#238

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Fix create_pull_request patch using stale origin/<branch> instead of merge-base#28960

Fix create_pull_request patch using stale origin/<branch> instead of merge-base#28960
mrjf merged 3 commits intomainfrom
copilot/fix-stale-origin-branch-patch

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		// contains exactly the agent's changes. See issue githubnext/tsessebe autoloop
		// failures for context.

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