From afb5d9a479e9c766c378cc520d3f4b99bc9acc16 Mon Sep 17 00:00:00 2001
From: Paul Bakaus <paul.bakaus@gmail.com>
Date: Sat, 25 Jul 2026 20:07:58 -0700
Subject: [PATCH] Guard non-standard default branches like conventional ones

Cursor Bugbot: sitting on a non-standard default such as trunk (the
origin/HEAD target) still ran candidate selection, where develop or main
could win and produce an integration-vs-integration diff. The guard now
treats the remote default branch as an integration branch alongside the
conventional names. Failing-first test: on trunk with a develop branch
present, the scope stays the working tree.

Prepared with AI assistance (Claude Code), directed by @pbakaus.

Co-Authored-By: Claude Code <noreply@anthropic.com>
---
 skill/scripts/context-signals.mjs |  8 +++++---
 tests/context-signals.test.mjs    | 20 ++++++++++++++++++++
 2 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/skill/scripts/context-signals.mjs b/skill/scripts/context-signals.mjs
index 61763e1bb..15e78213d 100644
--- a/skill/scripts/context-signals.mjs
+++ b/skill/scripts/context-signals.mjs
@@ -112,13 +112,15 @@ function gitSignals(cwd) {
   // signal may override that: an origin/HEAD or upstream naming a DIFFERENT
   // integration branch (sitting on develop while the remote default is
   // main) would produce exactly the integration-vs-integration divergence
-  // this detection exists to prevent.
-  const onIntegrationBranch = conventional.includes(branch);
+  // this detection exists to prevent. "Integration branch" means a
+  // conventional name OR the remote's default branch, so a non-standard
+  // default like trunk is guarded the same way.
+  const remoteHead = splitRemoteRef(run(['symbolic-ref', '--short', 'refs/remotes/origin/HEAD']));
+  const onIntegrationBranch = conventional.includes(branch) || branch === remoteHead?.name;
   let base = null;
   let baseRev = null;
   if (!onIntegrationBranch) {
     const upstream = asUpstream(run(['rev-parse', '--abbrev-ref', '--symbolic-full-name', '@{u}']));
-    const remoteHead = splitRemoteRef(run(['symbolic-ref', '--short', 'refs/remotes/origin/HEAD']));
     const candidates = [];
     const seen = new Set();
     const addCandidate = (name, revs) => {
diff --git a/tests/context-signals.test.mjs b/tests/context-signals.test.mjs
index 432737282..e2172d5da 100644
--- a/tests/context-signals.test.mjs
+++ b/tests/context-signals.test.mjs
@@ -376,6 +376,26 @@ describe('gatherSignals', () => {
     assert.deepEqual(s.git.changedFiles, ['src/Hero.tsx']);
   });
 
+  it('sitting on a non-standard default branch keeps the working-tree scope (#302)', async () => {
+    const { execFileSync } = await import('node:child_process');
+    const git = (...args) => execFileSync('git', args, { cwd: scratch, stdio: 'ignore' });
+    git('init', '-q', '-b', 'trunk');
+    git('config', 'user.email', 't@example.com');
+    git('config', 'user.name', 'Test');
+    write('src/App.tsx', 'export default 1;\n');
+    git('add', '.');
+    git('commit', '-qm', 'init');
+    git('branch', '-q', 'develop'); // a conventional name also exists
+    git('update-ref', 'refs/remotes/origin/trunk', 'HEAD');
+    git('symbolic-ref', 'refs/remotes/origin/HEAD', 'refs/remotes/origin/trunk');
+    write('src/App.tsx', 'export default 2;\n'); // dirty on trunk
+    const s = await gatherSignals(scratch);
+    // trunk IS the integration branch (origin/HEAD says so); develop must
+    // not win the candidate scan and produce a trunk-vs-develop diff.
+    assert.equal(s.git.base, null);
+    assert.deepEqual(s.git.changedFiles, ['src/App.tsx']);
+  });
+
   it('never diffs one integration branch against another (#302)', async () => {
     const { execFileSync } = await import('node:child_process');
     const git = (...args) => execFileSync('git', args, { cwd: scratch, stdio: 'ignore' });