fix(agents): harden shell adapter bridge and address double-check review feedback

- create_session.sh: add explicit case fallback for delegate_agent (R1)
- lib_py.agents: add spawn-spec, resume-spec, exit-key argv CLI subcommands (R2)
- resume_session.sh, stop_session.sh: replace python string interpolation with safe argv subcommands (R2)
- stop_session.sh: dynamically iterate adapter.identity_cache_fields (R3)
- verify_session.py, workspace_uuid.py: remove dead imports (R9/N4)
- tests/test_a4_adapter_contract.py: add CLI bridge subcommand, clean-env PYTHONPATH safety, and fallback contract tests (R12/N1)
- SKILL.md, docs, logs: synchronize IMPROVEMENTS.md, LOG.md, and resolve_session_id wording (R8/R10/R11)
- promote verified peer review reports for cline (e7b9812b) and claude (31730364)

.agents/skills/multi-agent-mux-stop/scripts/stop_session.sh

@@ -173,7 +173,7 @@ delegate_publish_event "$DELEGATE_JOB_ID" progress "terminating"
 graceful_stop() {
   local pane_pid exitkey
   pane_pid=$(herdr list-panes -t "$SESSION_NAME" -F '#{pane_pid}' 2>/dev/null | head -1 || true)
-  exitkey="$("$(_delegate_py_bin)" -c "from lib_py.agents.registry import get_adapter; a = get_adapter('$AGENT'); print(a.exit_key if a else '/exit')" 2>/dev/null || echo "/exit")"
+  exitkey="$("$(_delegate_py_bin)" -m lib_py.agents exit-key "$AGENT" 2>/dev/null || echo "/exit")"
   echo "graceful: send-keys '$exitkey' to $SESSION_NAME"
   send_keys_safe "$SESSION_NAME" "$exitkey" "stop$$" || echo "graceful: safe delivery failed (rc=$?) — falling back to kill chain"
   _wait_session_gone "$SESSION_NAME" 5 || true
@@ -280,14 +280,7 @@ if purge and purge_uuid:
     if ai.get('project_cwd') == ws:
         if adapter and (ai.get('session_id') == purge_uuid or ai.get('conversation_id') == purge_uuid):
             for field in adapter.identity_cache_fields:
-                ai.pop(field, None)
-            if 'session_id' in adapter.identity_cache_fields or 'session_jsonl' in adapter.identity_cache_fields:
-                ai['session_id'] = None
-                ai['session_jsonl'] = None
-            if 'conversation_id' in adapter.identity_cache_fields:
-                ai['conversation_id'] = None
-                ai['conversation_db'] = None
-                ai['conversation_brain_dir'] = None
+                ai[field] = None
 elif purge and not purge_uuid:
     print("WARN: --purge-conversation requested but no workspace-scoped UUID resolved; nothing purged", flush=True)