🤖 fix: ignore stale origin/HEAD in git status scripts

#1414 unified the review base with git status, but fallback branch detection still trusted refs/remotes/origin/HEAD.

Workspaces created from bundles can inherit a stale origin/HEAD (e.g. pointing at a feature branch), causing ahead/behind to be computed against the wrong remote ref.

This follow-up:
- Treats origin/HEAD as "auto-detect" even if configured as the base ref
- Makes generateGitStatusScript() ignore suspicious origin/HEAD values and prefer origin/main or origin/master
- Adds main↔master fallback when a configured origin/<branch> does not exist
- Updates GIT_FETCH_SCRIPT to derive the remote default branch via `git ls-remote --symref origin HEAD`
- Updates Sidebar story mocks to detect the status script via output markers
- Adds unit tests for parseGitShowBranchForStatus

Author: ammar-agent

src/browser/components/hooks/useGitBranchDetails.ts

@@ -184,10 +184,12 @@ export function useGitBranchDetails(
 # Get current branch
 CURRENT_BRANCH=$(git rev-parse --abbrev-ref HEAD 2>/dev/null || echo "main")
 
-# Get primary branch (main or master)
-PRIMARY_BRANCH=$(git branch -r 2>/dev/null | grep -E 'origin/(main|master)$' | head -1 | sed 's@^.*origin/@@' || echo "main")
-
-if [ -z "$PRIMARY_BRANCH" ]; then
+# Get primary branch (main or master) - check refs directly for reliability
+if git rev-parse --verify "refs/remotes/origin/main" >/dev/null 2>&1; then
+  PRIMARY_BRANCH="main"
+elif git rev-parse --verify "refs/remotes/origin/master" >/dev/null 2>&1; then
+  PRIMARY_BRANCH="master"
+else
   PRIMARY_BRANCH="main"
 fi
 

src/browser/stories/App.sidebar.stories.tsx

@@ -113,7 +113,7 @@ function createGitStatusExecutor(gitStatus?: Map<string, GitStatusFixture>) {
     }
 
     // GitStatusStore consolidated status script
-    if (script.includes("PRIMARY_BRANCH=$(git symbolic-ref refs/remotes/origin/HEAD")) {
+    if (script.includes("---PRIMARY---") && script.includes("---SHOW_BRANCH---")) {
       const output = createGitStatusOutput(status);
       return Promise.resolve({ success: true as const, output, exitCode: 0, wall_duration_ms: 50 });
     }

src/common/utils/git/gitStatus.ts

@@ -23,22 +23,46 @@ PREFERRED_BRANCH="${preferredBranch}"
 if [ -n "$PREFERRED_BRANCH" ]; then
   if git rev-parse --verify "refs/remotes/origin/$PREFERRED_BRANCH" >/dev/null 2>&1; then
     PRIMARY_BRANCH="$PREFERRED_BRANCH"
+  elif [ "$PREFERRED_BRANCH" = "main" ] && git rev-parse --verify "refs/remotes/origin/master" >/dev/null 2>&1; then
+    PRIMARY_BRANCH="master"
+  elif [ "$PREFERRED_BRANCH" = "master" ] && git rev-parse --verify "refs/remotes/origin/main" >/dev/null 2>&1; then
+    PRIMARY_BRANCH="main"
   fi
 fi
 
 # Fall back to auto-detection
 if [ -z "$PRIMARY_BRANCH" ]; then
-  # Method 1: symbolic-ref (fastest)
-  PRIMARY_BRANCH=$(git symbolic-ref refs/remotes/origin/HEAD 2>/dev/null | sed 's@^refs/remotes/origin/@@')
+  # symbolic-ref can be stale (e.g., when cloned from a bundle)
+  SYMREF_BRANCH=$(git symbolic-ref refs/remotes/origin/HEAD 2>/dev/null | sed 's@^refs/remotes/origin/@@')
+
+  # Trust symbolic-ref only if it looks like a default branch name
+  case "$SYMREF_BRANCH" in
+    main|master|develop|trunk|default|release)
+      if git rev-parse --verify "refs/remotes/origin/$SYMREF_BRANCH" >/dev/null 2>&1; then
+        PRIMARY_BRANCH="$SYMREF_BRANCH"
+      fi
+      ;;
+  esac
+
+  # Prefer origin/main or origin/master if present (handles stale origin/HEAD)
+  if [ -z "$PRIMARY_BRANCH" ]; then
+    if git rev-parse --verify "refs/remotes/origin/main" >/dev/null 2>&1; then
+      PRIMARY_BRANCH="main"
+    elif git rev-parse --verify "refs/remotes/origin/master" >/dev/null 2>&1; then
+      PRIMARY_BRANCH="master"
+    fi
+  fi
 
-  # Method 2: remote show origin (fallback)
+  # Fallback: ask origin (may require network)
   if [ -z "$PRIMARY_BRANCH" ]; then
     PRIMARY_BRANCH=$(git remote show origin 2>/dev/null | grep 'HEAD branch' | cut -d' ' -f5)
   fi
 
-  # Method 3: check for main or master
-  if [ -z "$PRIMARY_BRANCH" ]; then
-    PRIMARY_BRANCH=$(git branch -r 2>/dev/null | grep -E 'origin/(main|master)$' | head -1 | sed 's@^.*origin/@@')
+  # Last resort: use symbolic-ref if it points to an existing remote-tracking ref
+  if [ -z "$PRIMARY_BRANCH" ] && [ -n "$SYMREF_BRANCH" ]; then
+    if git rev-parse --verify "refs/remotes/origin/$SYMREF_BRANCH" >/dev/null 2>&1; then
+      PRIMARY_BRANCH="$SYMREF_BRANCH"
+    fi
   fi
 fi
 
@@ -48,8 +72,10 @@ if [ -z "$PRIMARY_BRANCH" ]; then
   exit 1
 fi
 
+BASE_REF="origin/$PRIMARY_BRANCH"
+
 # Get show-branch output for ahead/behind counts
-SHOW_BRANCH=$(git show-branch --sha1-name HEAD "origin/$PRIMARY_BRANCH" 2>/dev/null)
+SHOW_BRANCH=$(git show-branch --sha1-name HEAD "$BASE_REF" 2>/dev/null)
 
 if [ $? -ne 0 ]; then
   echo "ERROR: git show-branch failed"
@@ -62,7 +88,7 @@ DIRTY_COUNT=$(git status --porcelain 2>/dev/null | wc -l | tr -d ' ')
 # Compute line deltas (additions/deletions) vs merge-base with origin's primary branch.
 #
 # We emit *only* totals to keep output tiny (avoid output truncation in large repos).
-MERGE_BASE=$(git merge-base HEAD "origin/$PRIMARY_BRANCH" 2>/dev/null || echo "")
+MERGE_BASE=$(git merge-base HEAD "$BASE_REF" 2>/dev/null || echo "")
 
 # Outgoing: local changes vs merge-base (working tree vs base, includes uncommitted changes)
 OUTGOING_STATS="0 0"
@@ -76,7 +102,7 @@ fi
 # Incoming: remote primary branch changes vs merge-base
 INCOMING_STATS="0 0"
 if [ -n "$MERGE_BASE" ]; then
-  INCOMING_STATS=$(git diff --numstat "$MERGE_BASE" "origin/$PRIMARY_BRANCH" 2>/dev/null | awk '{ if ($1 == "-" || $2 == "-") next; add += $1; del += $2 } END { printf "%d %d", add+0, del+0 }')
+  INCOMING_STATS=$(git diff --numstat "$MERGE_BASE" "$BASE_REF" 2>/dev/null | awk '{ if ($1 == "-" || $2 == "-") next; add += $1; del += $2 } END { printf "%d %d", add+0, del+0 }')
   if [ -z "$INCOMING_STATS" ]; then
     INCOMING_STATS="0 0"
   fi
@@ -153,10 +179,10 @@ export function parseGitStatusScriptOutput(output: string): ParsedGitStatusOutpu
  * (e.g., IDE or user already fetched).
  *
  * Flow:
- * 1. ls-remote to get remote SHA (no lock, network only)
- * 2. cat-file to check if SHA exists locally (no lock)
- * 3. If local: skip fetch (no lock needed)
- * 4. If not local: fetch to get new commits (lock, but rare)
+ * 1. ls-remote --symref origin HEAD to get default branch + SHA (no lock, network only)
+ * 2. rev-parse to check local remote-tracking SHA (no lock)
+ * 3. If local already matches: skip fetch (no lock needed)
+ * 4. If not: fetch updates (lock, but rare)
  */
 export const GIT_FETCH_SCRIPT = `
 # Disable ALL prompts
@@ -165,19 +191,13 @@ export GIT_ASKPASS=echo
 export SSH_ASKPASS=echo
 export GIT_SSH_COMMAND="\${GIT_SSH_COMMAND:-ssh} -o BatchMode=yes -o StrictHostKeyChecking=accept-new"
 
-# Get primary branch name
-PRIMARY_BRANCH=$(git symbolic-ref refs/remotes/origin/HEAD 2>/dev/null | sed 's@^refs/remotes/origin/@@')
-if [ -z "$PRIMARY_BRANCH" ]; then
-  PRIMARY_BRANCH=$(git remote show origin 2>/dev/null | grep 'HEAD branch' | cut -d' ' -f5)
-fi
-if [ -z "$PRIMARY_BRANCH" ]; then
-  PRIMARY_BRANCH="main"
-fi
+# Determine remote default branch + SHA via ls-remote (no lock, network only)
+REMOTE_INFO=$(git ls-remote --symref origin HEAD 2>/dev/null || echo "")
+PRIMARY_BRANCH=$(printf '%s\n' "$REMOTE_INFO" | awk '$1=="ref:" && $3=="HEAD" {sub("^refs/heads/","",$2); print $2; exit}')
+REMOTE_SHA=$(printf '%s\n' "$REMOTE_INFO" | awk '$2=="HEAD" && $1!="ref:" {print $1; exit}')
 
-# Check remote SHA via ls-remote (no lock, network only)
-REMOTE_SHA=$(git ls-remote origin "refs/heads/$PRIMARY_BRANCH" 2>/dev/null | cut -f1)
-if [ -z "$REMOTE_SHA" ]; then
-  echo "SKIP: Could not get remote SHA"
+if [ -z "$PRIMARY_BRANCH" ] || [ -z "$REMOTE_SHA" ]; then
+  echo "SKIP: Could not get remote HEAD"
   exit 0
 fi
 

src/common/utils/git/parseGitStatus.test.ts

@@ -1,4 +1,4 @@
-import { parseGitRevList } from "./parseGitStatus";
+import { parseGitRevList, parseGitShowBranchForStatus } from "./parseGitStatus";
 
 // Base result shape with zero line deltas (parseGitRevList doesn't compute these)
 const base = {
@@ -39,3 +39,76 @@ describe("parseGitRevList", () => {
     expect(parseGitRevList("\t")).toBe(null);
   });
 });
+
+describe("parseGitShowBranchForStatus", () => {
+  test("parses 2-branch output correctly", () => {
+    const output = `! [HEAD] feat: add feature
+ ! [origin/main] fix: bug fix
+--
++  [cf9cbfb7] feat: add feature
+++ [306f4968] fix: bug fix`;
+
+    const result = parseGitShowBranchForStatus(output);
+    expect(result).not.toBeNull();
+    expect(result!.ahead).toBe(1);
+    expect(result!.behind).toBe(0);
+  });
+
+  test("parses 2-branch output with behind commits", () => {
+    const output = `! [HEAD] feat: add feature
+ ! [origin/main] latest on main
+--
++  [cf9cbfb7] feat: add feature
+ + [1] behind commit 1
+ + [2] behind commit 2
+ + [3] behind commit 3
+++ [base] common ancestor`;
+
+    const result = parseGitShowBranchForStatus(output);
+    expect(result).not.toBeNull();
+    expect(result!.ahead).toBe(1);
+    expect(result!.behind).toBe(3);
+  });
+
+  test("parses 2-branch output with many behind commits", () => {
+    const output = `! [HEAD] feat: add feature
+ ! [origin/main] latest on main
+--
++  [cf9cbfb7] feat: add feature
+ + [1] behind commit 1
+ + [2] behind commit 2
+ + [3] behind commit 3
+ + [4] behind commit 4
+ + [5] behind commit 5
+ + [6] behind commit 6
+ + [7] behind commit 7
+ + [8] behind commit 8
+ + [9] behind commit 9
+++ [base] common ancestor`;
+
+    const result = parseGitShowBranchForStatus(output);
+    expect(result).not.toBeNull();
+    expect(result!.ahead).toBe(1);
+    expect(result!.behind).toBe(9);
+  });
+
+  test("handles 3-branch output (misuse case)", () => {
+    // This tests what happens if 3-branch output is accidentally fed to the parser
+    // The parser uses columns 0 and 1, ignoring column 2
+    const output = `! [HEAD] feat: add feature
+ ! [origin/main] fix: bug fix
+  ! [origin/feature] feat: add feature
+---
++ + [cf9cbfb7] feat: add feature
+ ++ [306f4968] fix: bug fix`;
+
+    // With 3 columns: "+ +" means col0='+', col1=' ', col2='+'
+    // Parser sees col0='+', col1=' ' -> ahead
+    // With 3 columns: " ++" means col0=' ', col1='+', col2='+'
+    // Parser sees col0=' ', col1='+' -> behind
+    const result = parseGitShowBranchForStatus(output);
+    expect(result).not.toBeNull();
+    expect(result!.ahead).toBe(1); // "+ +" has col0='+', col1=' '
+    expect(result!.behind).toBe(1); // " ++" has col0=' ', col1='+'
+  });
+});