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/delegation/service.py

@@ -46,18 +46,54 @@ class DelegationService(object):
             registry_dir=self.registry_dir, **kw
         )
 
-    def publish_event(self, job_id, event, detail="", data=None, attempts=3):
-        """Publish one event. Returns the same exit status as the CLI (0 / 2)."""
+    def publish_event(self, job_id, event, detail="", data=None, attempts=3,
+                      expect_dispatch_token=None, attempt_id=None):
+        """Publish one event. Returns the same exit status as the CLI (0 / 2 / 4)."""
+        eff_dispatch_token = expect_dispatch_token
+        eff_attempt_id = attempt_id
+        if data and isinstance(data, dict):
+            if eff_dispatch_token is None:
+                eff_dispatch_token = data.get("dispatch_token")
+            if eff_attempt_id is None:
+                eff_attempt_id = data.get("attempt_id")
+
+        try:
+            rec = self.load_job(job_id)
+            actual_tok = rec.get("dispatch_token")
+            rec_attempt = rec.get("attempt_id", rec.get("iteration", 1))
+        except FileNotFoundError:
+            rec = None
+            actual_tok = None
+            rec_attempt = 1
+
+        if rec is not None and actual_tok is not None:
+            if eff_dispatch_token is None and eff_attempt_id is None:
+                if event in ("completed", "error", "cancelled") and rec_attempt > 1:
+                    logger.error("dispatch token required: redispatched job %s carries a dispatch token "
+                                 "but none was provided", job_id)
+                    return 4
+            elif eff_dispatch_token is not None and actual_tok != eff_dispatch_token:
+                return 4
+            elif eff_attempt_id is not None and rec_attempt != eff_attempt_id:
+                return 4
+        elif eff_dispatch_token is not None and actual_tok != eff_dispatch_token:
+            return 4
+
         prepared = publish_event.prepare_event(
             job_id=job_id, event=event, detail=detail,
             data=data, registry_dir=self.registry_dir,
+            dispatch_token=eff_dispatch_token, attempt_id=eff_attempt_id,
         )
         publisher = self._publisher
         if publisher is None:
             from lib_py.delegation.publisher import OneShotPublisher
             publisher = OneShotPublisher()
         ok, error = publisher.publish_with_retry(prepared, attempts=attempts)
-        publish_event.record_outcome(prepared, self.registry_dir, ok, error)
+        publish_event.record_outcome(
+            prepared, self.registry_dir, ok, error,
+            expected_dispatch_token=eff_dispatch_token,
+            expected_attempt=eff_attempt_id,
+        )
         return 0 if ok else 2
 
     def ensure_subscriber_daemon(self, job_id, workdir=None):