feat(agent): add full codex agent support (v4.2.0)

- Implement CodexAdapter in lib_py/agents/adapters/codex.py with safe flags and TUI readiness
- Extend create_session, resume_session, stop_session, and reconcile for codex CLI
- Support codex agent delegation and loop integration across all multi-agent skills
- Add unit, component, and contract test suites for codex integration
- Verify all 462 tests passing cleanly

tests/conftest.py

@@ -550,7 +550,8 @@ elif cmd1 == "agent":
             "agy": f"Antigravity Ready in {resolved_cwd}",
             "hermes": f"Hermes Ready in {resolved_cwd}",
             "grok": f"Grok Ready in {resolved_cwd}",
-            "opencode": f"OpenCode Ready in {resolved_cwd}"
+            "opencode": f"OpenCode Ready in {resolved_cwd}",
+            "codex": f"Codex Ready in {resolved_cwd}"
         }.get(agent_type, f"Ready in {resolved_cwd}")
 
         agents = state.get("agents", {})
@@ -581,7 +582,8 @@ elif cmd1 == "agent":
             "agy": "agy_conversation_id_own",
             "hermes": "hermes_conversation_id_own",
             "grok": "grok_session_id_own",
-            "opencode": "opencode_session_id_own"
+            "opencode": "opencode_session_id_own",
+            "codex": "codex_session_id_own"
         }
         own_key = own_key_map.get(agent_type)
         if own_key:
@@ -642,6 +644,21 @@ elif cmd1 == "agent":
             conn.execute("INSERT OR REPLACE INTO session (id, directory, time_created, cwd, created_at) VALUES (?, ?, ?, ?, ?)", (session_uuid, ws_abs, now_ms, ws_abs, time.time()))
             conn.commit()
             conn.close()
+        elif agent_type == "codex":
+            codex_home = os.environ.get("CODEX_HOME", os.path.join(home_dir, ".codex"))
+            os.makedirs(codex_home, exist_ok=True)
+            db_path = os.path.join(codex_home, "state_5.sqlite")
+            conn = sqlite3.connect(db_path)
+            conn.execute("CREATE TABLE IF NOT EXISTS threads (id TEXT PRIMARY KEY, cwd TEXT, rollout_path TEXT, created_at INTEGER, updated_at INTEGER)")
+            sessions_dir = os.path.join(codex_home, "sessions", "2026", "09", "05")
+            os.makedirs(sessions_dir, exist_ok=True)
+            rollout_file = os.path.join(sessions_dir, f"rollout-001-{session_uuid}.jsonl")
+            now_ts = int(time.time())
+            with open(rollout_file, "w") as rf:
+                rf.write(json.dumps({"payload": {"cwd": ws_abs, "id": session_uuid}}) + "\\\\n")
+            conn.execute("INSERT OR REPLACE INTO threads (id, cwd, rollout_path, created_at, updated_at) VALUES (?, ?, ?, ?, ?)", (session_uuid, ws_abs, rollout_file, now_ts, now_ts))
+            conn.commit()
+            conn.close()
 
         state["agents"] = agents
         save_state()
@@ -989,7 +1006,21 @@ sys.exit(0)
 """)
     opencode_bin.chmod(0o755)
 
-    # 6. uuidgen mock to guarantee isolated creation UUIDs
+    # 6. codex mock
+    codex_bin = bin_dir / "codex"
+    codex_bin.write_text("""#!/usr/bin/env python3
+import sys, os
+args = sys.argv[1:]
+if len(args) >= 1 and args[0] == "--version":
+    print("codex 0.1.0")
+    sys.exit(0)
+if len(args) >= 1 and args[0] == "delete":
+    sys.exit(0)
+sys.exit(0)
+""")
+    codex_bin.chmod(0o755)
+
+    # 7. uuidgen mock to guarantee isolated creation UUIDs
     uuidgen_bin = bin_dir / "uuidgen"
     uuidgen_bin.write_text("""#!/usr/bin/env python3
 import uuid