diff --git a/src/agentkit/core/phase.py b/src/agentkit/core/phase.py
index 8101c24..d6922cc 100644
--- a/src/agentkit/core/phase.py
+++ b/src/agentkit/core/phase.py
@@ -55,12 +55,6 @@ class PhaseState(enum.Enum):
 # Wildcard token meaning "all tools allowed in this phase".
 WILDCARD = "*"
 
-# Legacy regex-based bash filter. Kept for backward compatibility with configs
-# that pass a `re.Pattern` into `bash_command_filter`. New default uses
-# `ShellTool._is_dangerous` (a Callable) which closes the regex ceiling
-# (missed `:>file`, `dd of=file`, etc. — see Wave 4 U1).
-_DEFAULT_BASH_FILTER = re.compile(r"\b(rm|mv|cp|mkdir|rmdir|chmod|chown)\b|(?<!\S)>|>>")
-
 
 @dataclass(slots=True)
 class PhasePolicy:
diff --git a/src/agentkit/server/frontend/src/stores/chat.ts b/src/agentkit/server/frontend/src/stores/chat.ts
index b49e5be..13f446d 100644
--- a/src/agentkit/server/frontend/src/stores/chat.ts
+++ b/src/agentkit/server/frontend/src/stores/chat.ts
@@ -1433,8 +1433,7 @@ export const useChatStore = defineStore("chat", () => {
       }
 
       case "phase_violation": {
-        // Track current phase from violation data (backend doesn't emit
-        // phase_changed yet — U4 frontend is forward-compatible).
+        // Track current phase from violation data.
         currentPhase.value = data.data.current_phase;
         const violation = {
           phase: data.data.current_phase,
diff --git a/src/agentkit/server/frontend/tests/unit/stores/chat-phase.test.ts b/src/agentkit/server/frontend/tests/unit/stores/chat-phase.test.ts
index d25751f..7e86aa5 100644
--- a/src/agentkit/server/frontend/tests/unit/stores/chat-phase.test.ts
+++ b/src/agentkit/server/frontend/tests/unit/stores/chat-phase.test.ts
@@ -54,7 +54,11 @@ describe('chat store — PLAN_EXEC phase state (U4)', () => {
     expect(store.isPlanExec).toBe(true)
   })
 
-  it('phaseViolations capped at 5 entries', async () => {
+  it('phaseViolations array is directly mutable for test fixtures', async () => {
+    // Direct mutation bypasses the capping logic in handleWsMessage;
+    // the cap is enforced inside the case handler, not as a setter.
+    // This test verifies the array is accessible; the cap-at-5 behavior
+    // is exercised through handleWsMessage in the U5 E2E test.
     const { useChatStore } = await import('@/stores/chat')
     const store = useChatStore()
     for (let i = 0; i < 7; i++) {
@@ -69,9 +73,6 @@ describe('chat store — PLAN_EXEC phase state (U4)', () => {
         },
       ]
     }
-    // Direct mutation bypasses the capping logic in handleWsMessage;
-    // the cap is enforced inside the case handler, not as a setter.
-    // This test just verifies the array is accessible.
     expect(store.phaseViolations.length).toBe(7)
   })
 })
diff --git a/src/agentkit/server/routes/chat.py b/src/agentkit/server/routes/chat.py
index 54cfb12..7b2bba5 100644
--- a/src/agentkit/server/routes/chat.py
+++ b/src/agentkit/server/routes/chat.py
@@ -6,7 +6,7 @@ import asyncio
 import hmac
 import json
 import logging
-from typing import Any
+from typing import Any, TYPE_CHECKING
 
 import os
 import uuid
@@ -33,6 +33,11 @@ from agentkit.session.manager import SessionManager
 from agentkit.session.models import MessageRole, SessionStatus
 from agentkit.tools.advance_phase import AdvancePhaseTool
 
+if TYPE_CHECKING:
+    from agentkit.llm.gateway import LLMGateway
+    from agentkit.server.config import ServerConfig
+    from agentkit.tools.base import Tool
+
 logger = logging.getLogger(__name__)
 
 router = APIRouter(prefix="/chat", tags=["chat"])
@@ -536,12 +541,12 @@ def _message_to_response(msg) -> MessageResponse:
 
 def _build_phase_engine(
     *,
-    server_config: Any,
-    llm_gateway: Any,
+    server_config: ServerConfig | None,
+    llm_gateway: LLMGateway,
     execution_mode: ExecutionMode,
-    base_tools: list,
+    base_tools: list[Tool],
     session_id: str = "",
-) -> tuple[ReActEngine | None, list | None, str | None]:
+) -> tuple[ReActEngine | None, list[Tool] | None, str | None]:
     """Build a PLAN_EXEC engine with PhasePolicy + AdvancePhaseTool.
 
     Encapsulates the WS path's phase_policy construction so the REST path
diff --git a/tests/integration/test_plan_exec_e2e.py b/tests/integration/test_plan_exec_e2e.py
index a30386f..2dd7da0 100644
--- a/tests/integration/test_plan_exec_e2e.py
+++ b/tests/integration/test_plan_exec_e2e.py
@@ -322,6 +322,8 @@ class TestPlanExecE2EEdgeCases:
             events.append(ev)
 
         # Engine should have transitioned out of PLANNING (auto-advance fired).
+        # Weak assertion: auto_advance_after_steps=2 may fire multiple times
+        # (PLANNING→BUILDING→VERIFICATION), so we only assert it left PLANNING.
         assert engine.current_phase != PhaseState.PLANNING
         # All 3 search calls dispatched (search is allowed in both PLANNING and BUILDING).
         assert search.call_count == 3
diff --git a/tests/unit/test_chat_plan_exec_ws.py b/tests/unit/test_chat_plan_exec_ws.py
index 09c8750..22ab490 100644
--- a/tests/unit/test_chat_plan_exec_ws.py
+++ b/tests/unit/test_chat_plan_exec_ws.py
@@ -235,6 +235,7 @@ class TestRestPlanExec:
             json={"content": "Hello"},
         )
         # 500 is acceptable (mock gateway), but it must NOT be the PLAN_EXEC error.
+        assert msg_resp.status_code != 501, "REACT fallback should not return 501"
         if msg_resp.status_code == 500:
             assert "phase policy error" not in msg_resp.json().get("detail", "")