feat(pipeline): push-on-retire — no stranded commits when a stage completes

The pipeline retires a stage the instant its completion marker appears; if the agent wrote the marker
before its final 'git push' landed, its last commits were stranded locally (observed: a review stage
left 7 unpushed commits). Now, before retiring a COMPLETED stage, the watchdog does a best-effort
'git push origin HEAD:main' in that stage's dir (never raises; 90s timeout). Guarantees the deliverable
reaches the remote.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UWTdUq2bsic7JZGqJp3nD6

agents.py

@@ -977,6 +977,25 @@ def _pipeline_marker(cfg, stage):
     p = Path(stage["done"])
     return p if p.is_absolute() else Path(cfg["project_dir"]) / stage["done"]
 
+def _pipeline_push_on_retire(agent):
+    """Best-effort `git push` in a completing stage's dir before it's retired, so its final commits
+    aren't stranded locally if it wrote its completion marker before its last push landed (a race:
+    the pipeline retires a stage the instant its marker appears). Never raises; logs the outcome."""
+    d = agent.get("dir")
+    if not d or not (Path(d) / ".git").exists():
+        return
+    try:
+        r = subprocess.run(["git", "-C", d, "push", "origin", "HEAD:main"],
+                           env={**os.environ, "GIT_SSH_COMMAND": "ssh -o BatchMode=yes"},
+                           capture_output=True, text=True, timeout=90)
+        if r.returncode == 0:
+            log(f"pipeline: pushed {agent['name']!r} before retiring (no stranded commits)")
+        elif "up-to-date" not in (r.stderr + r.stdout).lower():
+            log(f"pipeline: push-on-retire for {agent['name']!r} nonzero (non-fatal): "
+                f"{(r.stderr or r.stdout).strip().splitlines()[-1:] }")
+    except Exception as e:
+        log(f"pipeline: push-on-retire for {agent['name']!r} failed (non-fatal): {e}")
+
 def pipeline_check(cfg):
     """Reconcile the [pipeline]: run the first stage whose completion marker is absent, retire every
     other pipeline agent. Returns the ACTIVE stage's agent dict (so the watchdog stall/heal-watches it),
@@ -1000,6 +1019,10 @@ def pipeline_check(cfg):
                 log(f"pipeline: advancing → start stage {ag['name']!r}")
                 start_agent(cfg, ag, force=True)
         elif alive:
+            # Retiring a non-active stage. If it's a COMPLETED stage (its marker exists), push its repo
+            # first so final commits written just before the marker aren't stranded locally.
+            if _pipeline_marker(cfg, st).exists():
+                _pipeline_push_on_retire(ag)
             log(f"pipeline: retire stage {ag['name']!r} (complete or not yet active)")
             kill_session(ag["session"])
     if active is None: