🤖 fix: git status indicator showing wrong behind count

When mux creates workspaces from bundles, origin/HEAD can be stale
(pointing to a feature branch instead of main). The git status scripts
were trusting symbolic-ref as the first method to find the primary
branch, causing ahead/behind to be calculated against the wrong ref.

Fix: Check origin/main and origin/master refs directly before falling
back to origin/HEAD. This is fast (local ref lookup) and reliable.

Additionally:
- Changed default review base from HEAD to origin/main
- Git status now uses the review base ref for ahead/behind calculations,
  creating consistency between the review panel and git status indicator
- Added generateGitStatusScript() to support custom base refs

Affected scripts:
- GIT_STATUS_SCRIPT (ahead/behind calculation)
- GIT_FETCH_SCRIPT (smart fetching)
- useGitBranchDetails (hover card display)

Also adds test coverage for parseGitShowBranchForStatus.

Author: ammar-agent

src/browser/components/RightSidebar/CodeReview/ReviewControls.tsx

@@ -43,7 +43,10 @@ export const ReviewControls: React.FC<ReviewControlsProps> = ({
   lastRefreshInfo,
 }) => {
   // Global default base (used for new workspaces)
-  const [defaultBase, setDefaultBase] = usePersistedState<string>("review-default-base", "HEAD");
+  const [defaultBase, setDefaultBase] = usePersistedState<string>(
+    "review-default-base",
+    "origin/main"
+  );
 
   const handleBaseChange = (value: string) => {
     onFiltersChange({ ...filters, diffBase: value });

src/browser/components/RightSidebar/CodeReview/ReviewPanel.tsx

@@ -288,7 +288,7 @@ export const ReviewPanel: React.FC<ReviewPanelProps> = ({
   );
 
   // Global default base (shared across all workspaces)
-  const [defaultBase] = usePersistedState<string>("review-default-base", "HEAD");
+  const [defaultBase] = usePersistedState<string>("review-default-base", "origin/main");
 
   // Persist diff base per workspace (falls back to global default)
   const [diffBase, setDiffBase] = usePersistedState(`review-diff-base:${workspaceId}`, defaultBase);

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/stores/GitStatusStore.ts

@@ -3,10 +3,11 @@ import type { AppRouter } from "@/node/orpc/router";
 import type { FrontendWorkspaceMetadata, GitStatus } from "@/common/types/workspace";
 import { parseGitShowBranchForStatus } from "@/common/utils/git/parseGitStatus";
 import {
-  GIT_STATUS_SCRIPT,
+  generateGitStatusScript,
   GIT_FETCH_SCRIPT,
   parseGitStatusScriptOutput,
 } from "@/common/utils/git/gitStatus";
+import { readPersistedState } from "@/browser/hooks/usePersistedState";
 import { useSyncExternalStore } from "react";
 import { MapStore } from "./MapStore";
 import { isSSHRuntime } from "@/common/types/runtime";
@@ -297,9 +298,13 @@ export class GitStatusStore {
     }
 
     try {
+      // Use global default base ref for git status (defaults to origin/main)
+      const baseRef = readPersistedState<string>("review-default-base", "origin/main");
+      const script = generateGitStatusScript(baseRef);
+
       const result = await this.client.workspace.executeBash({
         workspaceId: metadata.id,
-        script: GIT_STATUS_SCRIPT,
+        script,
         options: { timeout_secs: 5 },
       });
 

src/common/utils/git/gitStatus.ts

@@ -4,30 +4,125 @@
  */
 
 /**
- * Bash script to get git status for a workspace.
- * Returns structured output with primary branch, show-branch, and dirty status.
+ * Generate bash script to get git status for a workspace.
+ * Returns structured output with base ref, show-branch, and dirty status.
+ *
+ * @param baseRef - The ref to compare against (e.g., "origin/main", "origin/develop").
+ *                  If not provided, auto-detects origin/main or origin/master.
  */
-export const GIT_STATUS_SCRIPT = `
+export function generateGitStatusScript(baseRef?: string): string {
+  // If baseRef is provided and looks valid, use it with fallback to auto-detection
+  // Otherwise fall back to auto-detection directly
+  if (baseRef?.startsWith("origin/")) {
+    // Script that tries provided base first, falls back to auto-detection
+    return `
+# Try provided base ref first, fall back to auto-detection if it doesn't exist
+PREFERRED_BASE="${baseRef}"
+BASE_REF=""
+
+if git rev-parse --verify "$PREFERRED_BASE" >/dev/null 2>&1; then
+  BASE_REF="$PREFERRED_BASE"
+else
+  # Provided base doesn't exist, auto-detect primary branch
+  if git rev-parse --verify "refs/remotes/origin/main" >/dev/null 2>&1; then
+    BASE_REF="origin/main"
+  elif git rev-parse --verify "refs/remotes/origin/master" >/dev/null 2>&1; then
+    BASE_REF="origin/master"
+  fi
+fi
+
+# Final fallback
+if [ -z "$BASE_REF" ]; then
+  echo "ERROR: Could not find base ref"
+  exit 1
+fi
+
+# Get show-branch output for ahead/behind counts
+SHOW_BRANCH=$(git show-branch --sha1-name HEAD "$BASE_REF" 2>/dev/null)
+
+if [ $? -ne 0 ]; then
+  echo "ERROR: git show-branch failed"
+  exit 1
+fi
+
+# Check for dirty (uncommitted changes)
+DIRTY_COUNT=$(git status --porcelain 2>/dev/null | wc -l | tr -d ' ')
+
+# Compute line deltas vs merge-base
+MERGE_BASE=$(git merge-base HEAD "$BASE_REF" 2>/dev/null || echo "")
+
+OUTGOING_STATS="0 0"
+if [ -n "$MERGE_BASE" ]; then
+  OUTGOING_STATS=$(git diff --numstat "$MERGE_BASE" 2>/dev/null | awk '{ if ($1 == "-" || $2 == "-") next; add += $1; del += $2 } END { printf "%d %d", add+0, del+0 }')
+  if [ -z "$OUTGOING_STATS" ]; then
+    OUTGOING_STATS="0 0"
+  fi
+fi
+
+INCOMING_STATS="0 0"
+if [ -n "$MERGE_BASE" ]; then
+  INCOMING_STATS=$(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
+fi
+
+# Output sections (BASE_REF without origin/ prefix for consistency)
+echo "---PRIMARY---"
+echo "$BASE_REF" | sed 's@^origin/@@'
+echo "---SHOW_BRANCH---"
+echo "$SHOW_BRANCH"
+echo "---DIRTY---"
+echo "$DIRTY_COUNT"
+echo "---LINE_DELTA---"
+echo "$OUTGOING_STATS $INCOMING_STATS"
+`;
+  }
+
+  // Auto-detect primary branch
+  return `
 # Get primary branch - try multiple methods
+# Note: symbolic-ref can return stale values when cloned from bundles,
+# but we should trust it if it's a sensible default branch name.
 PRIMARY_BRANCH=""
 
 # Method 1: symbolic-ref (fastest)
-PRIMARY_BRANCH=$(git symbolic-ref refs/remotes/origin/HEAD 2>/dev/null | sed 's@^refs/remotes/origin/@@')
+SYMREF_BRANCH=$(git symbolic-ref refs/remotes/origin/HEAD 2>/dev/null | sed 's@^refs/remotes/origin/@@')
+
+# Accept symbolic-ref if it's a known default branch name (not a feature branch)
+# Common default branches: main, master, develop, trunk, default, release
+case "$SYMREF_BRANCH" in
+  main|master|develop|trunk|default|release)
+    PRIMARY_BRANCH="$SYMREF_BRANCH"
+    ;;
+esac
 
-# Method 2: remote show origin (fallback)
+# Method 2: check for main or master directly (fast, reliable fallback)
+# This handles cases where symbolic-ref points to a stale feature branch
 if [ -z "$PRIMARY_BRANCH" ]; then
-  PRIMARY_BRANCH=$(git remote show origin 2>/dev/null | grep 'HEAD branch' | cut -d' ' -f5)
+  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 3: If symbolic-ref gave us something and main/master don't exist,
+# trust the symbolic-ref value (handles non-standard default branches)
+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
 
-# Method 3: check for main or master
+# Method 4: remote show origin (slow, network call, last resort)
 if [ -z "$PRIMARY_BRANCH" ]; then
-  PRIMARY_BRANCH=$(git branch -r 2>/dev/null | grep -E 'origin/(main|master)$' | head -1 | sed 's@^.*origin/@@')
+  PRIMARY_BRANCH=$(git remote show origin 2>/dev/null | grep 'HEAD branch' | cut -d' ' -f5)
 fi
 
-# Exit if we can't determine primary branch
+# Final fallback: assume main
 if [ -z "$PRIMARY_BRANCH" ]; then
-  echo "ERROR: Could not determine primary branch"
-  exit 1
+  PRIMARY_BRANCH="main"
 fi
 
 # Get show-branch output for ahead/behind counts
@@ -74,6 +169,13 @@ echo "$DIRTY_COUNT"
 echo "---LINE_DELTA---"
 echo "$OUTGOING_STATS $INCOMING_STATS"
 `;
+}
+
+/**
+ * @deprecated Use generateGitStatusScript() instead
+ * Bash script to get git status for a workspace (auto-detects primary branch).
+ */
+export const GIT_STATUS_SCRIPT = generateGitStatusScript();
 
 /**
  * Parse the output from GIT_STATUS_SCRIPT.
@@ -142,10 +244,32 @@ 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=$(git symbolic-ref refs/remotes/origin/HEAD 2>/dev/null | sed 's@^refs/remotes/origin/@@')
+# Note: symbolic-ref can return stale values, but trust it if it's a sensible name
+PRIMARY_BRANCH=""
+SYMREF_BRANCH=$(git symbolic-ref refs/remotes/origin/HEAD 2>/dev/null | sed 's@^refs/remotes/origin/@@')
+
+# Accept symbolic-ref if it's a known default branch name
+case "$SYMREF_BRANCH" in
+  main|master|develop|trunk|default|release)
+    PRIMARY_BRANCH="$SYMREF_BRANCH"
+    ;;
+esac
+
+# Fallback: check for main or master directly
 if [ -z "$PRIMARY_BRANCH" ]; then
-  PRIMARY_BRANCH=$(git remote show origin 2>/dev/null | grep 'HEAD branch' | cut -d' ' -f5)
+  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
+
+# Trust symbolic-ref if main/master don't exist (non-standard default branches)
+if [ -z "$PRIMARY_BRANCH" ] && [ -n "$SYMREF_BRANCH" ]; then
+  PRIMARY_BRANCH="$SYMREF_BRANCH"
 fi
+
+# Final fallback
 if [ -z "$PRIMARY_BRANCH" ]; then
   PRIMARY_BRANCH="main"
 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='+'
+  });
+});