fix(consistency): correct behind-remote detection to not trigger on local-ahead

_detect_behind_remote was comparing HEAD != @{u} which incorrectly
triggered C-16 when the local repo had unpushed commits. Fixed to use
git rev-list --count HEAD..@{u} which only counts commits the remote
has that local lacks. Adds test_returns_false_when_local_ahead.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

scripts/consistency_check.py

@@ -748,8 +748,10 @@ def _check_ghost_duplicates(
 # ---------------------------------------------------------------------------
 
 def _detect_behind_remote(repo_path: str) -> bool:
-    """Return True if the local repo is behind its remote tracking branch.
+    """Return True if the remote tracking branch has commits the local repo lacks.
 
+    "Ahead" (local has unpushed commits) is NOT considered behind.
+    "Diverged" is treated as behind (remote progress could be lost).
     Best-effort: returns False on any error (offline, no remote, etc.) so that
     check-only mode is never blocked by network issues.
     """
@@ -758,15 +760,15 @@ def _detect_behind_remote(repo_path: str) -> bool:
             ["git", "-C", repo_path, "fetch", "--quiet", "origin"],
             capture_output=True, timeout=15,
         )
-        local = subprocess.run(
+        # Count commits in remote that are not in local.
-            ["git", "-C", repo_path, "rev-parse", "HEAD"],
+        # git rev-list HEAD..@{u} → commits remote has that local lacks.
+        result = subprocess.run(
+            ["git", "-C", repo_path, "rev-list", "--count", "HEAD..@{u}"],
             capture_output=True, text=True, timeout=5,
-        ).stdout.strip()
+        )
-        remote = subprocess.run(
+        if result.returncode != 0:
-            ["git", "-C", repo_path, "rev-parse", "@{u}"],
+            return False  # no upstream configured or other error
-            capture_output=True, text=True, timeout=5,
+        return int(result.stdout.strip() or "0") > 0
-        ).stdout.strip()
-        return bool(local and remote and local != remote)
     except Exception:
         return False
 

tests/test_consistency_check.py

@@ -450,6 +450,26 @@ class TestDetectBehindRemote:
         subprocess.run(["git", "-C", str(clone), "push", "origin", "HEAD"], capture_output=True)
         assert _detect_behind_remote(str(clone)) is False
 
+    def test_returns_false_when_local_ahead(self, tmp_path):
+        """Local has unpushed commits — NOT considered behind."""
+        import subprocess
+        bare = tmp_path / "bare.git"
+        clone = tmp_path / "clone"
+        bare.mkdir()
+        subprocess.run(["git", "init", "--bare", str(bare)], capture_output=True)
+        subprocess.run(["git", "clone", str(bare), str(clone)], capture_output=True)
+        subprocess.run(
+            ["git", "-C", str(clone), "commit", "--allow-empty", "-m", "init"],
+            capture_output=True,
+        )
+        subprocess.run(["git", "-C", str(clone), "push", "origin", "HEAD:main"], capture_output=True)
+        # Add a local-only commit (not pushed)
+        subprocess.run(
+            ["git", "-C", str(clone), "commit", "--allow-empty", "-m", "local only"],
+            capture_output=True,
+        )
+        assert _detect_behind_remote(str(clone)) is False
+
     def test_returns_true_when_behind(self, tmp_path):
         """Remote has a commit the clone doesn't → clone is behind."""
         import subprocess