fix(issue-6): fail-closed registry timeout and TUI turn handshake

- Introduce finalize_unfinished in multi-agent-mux-delegate-job for fail-closed atomic transitions
- Enforce CAS dispatch_token and attempt_id pinning across engine, CLI, and lifecycle scripts
- Integrate Herdr wait_for_agent_idle turn handshake to prevent prompt loss and race conditions
- Resolve bash 3.2 set -u empty array expansion compatibility in lib.sh
- Preserve Issue #5 R2 contract in CAS transition engine (engine.py, publish_event.py, service.py)
- Add comprehensive regression suites (test_issue6_fail_closed.py, test_issue6_turn_handshake.py)
- Bump lockstep framework and skills to v4.4.1 across lib.sh, eager.py, VERSIONS.md, 8 SKILL.md
- Synchronize documentation (IMPROVEMENTS.md, MESSAGING.md, state-transitions.md, task.md, phase5-e2e.md)
- Unanimous PASS achieved across 4 reviewer team leaders (Claude, Codex, OpenCode, Grok)

Closes #6

.agents/skills/lib_py/loop/runner.py

@@ -59,6 +59,7 @@ class LoopRunner:
         self.mam_dir = self.workspace_root / ".mam"
         self.checkpoint_file = self.mam_dir / "loop-checkpoint.json"
         self.created_jobs: List[str] = []
+        self.failed_submit_jobs: Set[str] = set()
         self.current_plan = ""
         self.plan_job_id: Optional[str] = None
         self.base_commit = ""
@@ -262,27 +263,49 @@ class LoopRunner:
         if not wrapper_script.exists():
             wrapper_script = Path(__file__).resolve().parent.parent / "multi-agent-mux-delegate-job" / "multi-agent-mux-delegate-job"
 
-        cmd = [
-            "bash", str(wrapper_script), "submit",
-            "--agent-session", f"herdr:{agent_session}",
-            "--agent", agent_type,
-            "--type", "direct",
-            "--role", role,
-            "--prompt", prompt,
-        ]
-        env = dict(os.environ)
-        if "DELEGATE_JOB_PYTHON" not in env:
-            env["DELEGATE_JOB_PYTHON"] = sys.executable
+        def _run_cmd(p_text: str):
+            cmd = [
+                "bash", str(wrapper_script), "submit",
+                "--agent-session", f"herdr:{agent_session}",
+                "--agent", agent_type,
+                "--type", "direct",
+                "--role", role,
+                "--prompt", p_text,
+            ]
+            env = dict(os.environ)
+            if "DELEGATE_JOB_PYTHON" not in env:
+                env["DELEGATE_JOB_PYTHON"] = sys.executable
+            return subprocess.run(cmd, capture_output=True, text=True, cwd=str(self.workspace_root), env=env)
+
+        res = _run_cmd(prompt)
+        match = re.search(r"registered job:\s*([A-Za-z0-9_-]+)", res.stdout)
+        job_id = match.group(1) if match else None
 
-        res = subprocess.run(cmd, capture_output=True, text=True, cwd=str(self.workspace_root), env=env)
         if res.returncode != 0:
             log_error(f"delegate_job submit failed (exit {res.returncode}):\n{res.stderr or res.stdout}")
+            if res.returncode == 5:
+                # rc=5 (session_busy): MAM_SESSION_BUSY_RETRY_S wait, then 1 retry
+                retry_s = int(os.environ.get("MAM_SESSION_BUSY_RETRY_S", "30"))
+                if retry_s > 0:
+                    time.sleep(retry_s)
+                res_retry = _run_cmd(prompt)
+                match_retry = re.search(r"registered job:\s*([A-Za-z0-9_-]+)", res_retry.stdout)
+                if match_retry:
+                    job_id_retry = match_retry.group(1)
+                    self.created_jobs.append(job_id_retry)
+                    self._record_checkpoint()
+                    if res_retry.returncode != 0:
+                        self.failed_submit_jobs.add(job_id_retry)
+                        log_error(f"delegate_job retry failed (exit {res_retry.returncode}):\n{res_retry.stderr or res_retry.stdout}")
+                    return job_id_retry
+            if job_id:
+                self.created_jobs.append(job_id)
+                self.failed_submit_jobs.add(job_id)
+                self._record_checkpoint()
+                return job_id
             return None
 
-        # Extract Job ID (pattern: 'registered job: [A-Za-z0-9]*')
-        match = re.search(r"registered job:\s*([A-Za-z0-9]+)", res.stdout)
-        if match:
-            job_id = match.group(1)
+        if job_id:
             self.created_jobs.append(job_id)
             self._record_checkpoint()
             return job_id
@@ -290,11 +313,17 @@ class LoopRunner:
 
     def wait_for_job(self, job_id: str, max_wait: int = 3900, check_interval: float = 1.0) -> bool:
         """Blocking wait for job completion or error with safety timeout."""
+        if job_id in self.failed_submit_jobs:
+            # Submit command for this job failed (rc!=0). Cap wait to 5s to avoid 3900s hang
+            max_wait = min(max_wait, 5.0)
+
         if self.verbose:
             log_info(f"Monitoring job '{job_id}' for status changes (timeout: {max_wait}s)...")
 
         job_file = self.mam_dir / "jobs" / f"{job_id}.json"
         start_time = time.time()
+        missing_count = 0
+        unknown_count = 0
 
         while time.time() - start_time < max_wait:
             if self.interrupted:
@@ -306,6 +335,17 @@ class LoopRunner:
                         status = json.load(f).get("status", "unknown")
                 except Exception:
                     status = "unknown"
+            else:
+                missing_count += 1
+                if missing_count >= 5 and (time.time() - start_time) >= min(max_wait, 5.0):
+                    log_error(f"Job record '{job_file}' not found on disk; aborting wait.")
+                    return False
+
+            if status == "unknown":
+                unknown_count += 1
+                if unknown_count >= 5 and (time.time() - start_time) >= min(max_wait, 5.0):
+                    log_error(f"Job '{job_id}' record unreadable / status unknown; aborting wait.")
+                    return False
 
             if status == "completed":
                 if self.verbose: