diff --git a/conductor/tracks.md b/conductor/tracks.md
index f77dedd..249b5f2 100644
--- a/conductor/tracks.md
+++ b/conductor/tracks.md
@@ -20,7 +20,7 @@ This file tracks all major tracks for the project. Each track has its own detail
 4. [x] **Track: Robust JSON Parsing for Tech Lead**
 *Link: [./tracks/robust_json_parsing_tech_lead_20260302/](./tracks/robust_json_parsing_tech_lead_20260302/)*
 
-5. [ ] **Track: Concurrent Tier Source Isolation**
+5. [~] **Track: Concurrent Tier Source Isolation**
 *Link: [./tracks/concurrent_tier_source_tier_20260302/](./tracks/concurrent_tier_source_tier_20260302/)*
 
 6. [ ] **Track: Manual UX Validation & Polish**
diff --git a/conductor/tracks/concurrent_tier_source_tier_20260302/plan.md b/conductor/tracks/concurrent_tier_source_tier_20260302/plan.md
index 5842fe8..b4260ae 100644
--- a/conductor/tracks/concurrent_tier_source_tier_20260302/plan.md
+++ b/conductor/tracks/concurrent_tier_source_tier_20260302/plan.md
@@ -3,8 +3,8 @@
 > **TEST DEBT FIX:** Due to ongoing test architecture instability (documented in `test_architecture_integrity_audit_20260304`), do NOT write new `live_gui` integration tests for this track. Rely strictly on in-process `unittest.mock` for `ai_client` concurrency verification.
 
 ## Phase 1: Thread-Local Context Refactoring
-- [ ] Task: Initialize MMA Environment `activate_skill mma-orchestrator`
-- [ ] Task: Refactor `ai_client` to `threading.local()`
+- [x] Task: Initialize MMA Environment `activate_skill mma-orchestrator`
+- [~] Task: Refactor `ai_client` to `threading.local()`
     - [ ] WHERE: `ai_client.py`
     - [ ] WHAT: Replace `current_tier = None` with `_local_context = threading.local()`. Implement safe getters/setters for the tier.
     - [ ] HOW: Use standard `threading.local` attributes.
diff --git a/config.toml b/config.toml
index 22677ac..7a07341 100644
--- a/config.toml
+++ b/config.toml
@@ -1,5 +1,5 @@
 [ai]
-provider = "gemini"
+provider = "gemini_cli"
 model = "gemini-2.5-flash-lite"
 temperature = 0.0
 max_tokens = 8192
@@ -15,7 +15,7 @@ paths = [
     "C:\\projects\\manual_slop\\tests\\artifacts\\temp_livetoolssim.toml",
     "C:\\projects\\manual_slop\\tests\\artifacts\\temp_liveexecutionsim.toml",
 ]
-active = "C:\\projects\\manual_slop\\tests\\artifacts\\temp_livetoolssim.toml"
+active = "C:\\projects\\manual_slop\\tests\\artifacts\\temp_liveexecutionsim.toml"
 
 [gui.show_windows]
 "Context Hub" = true
diff --git a/project_history.toml b/project_history.toml
index 5926df4..737259d 100644
--- a/project_history.toml
+++ b/project_history.toml
@@ -8,5 +8,5 @@ active = "main"
 
 [discussions.main]
 git_commit = ""
-last_updated = "2026-03-06T00:19:13"
+last_updated = "2026-03-06T12:39:50"
 history = []
diff --git a/src/ai_client.py b/src/ai_client.py
index 36a917a..c8ecaaa 100644
--- a/src/ai_client.py
+++ b/src/ai_client.py
@@ -86,8 +86,16 @@ comms_log_callback: Optional[Callable[[dict[str, Any]], None]] = None
 # Injected by gui.py - called whenever a tool call completes.
 tool_log_callback: Optional[Callable[[str, str], None]] = None
 
-# Set by caller tiers before ai_client.send(); cleared in finally.
-current_tier: Optional[str] = None
+_local_storage = threading.local()
+
+def get_current_tier() -> Optional[str]:
+ """Returns the current tier from thread-local storage."""
+ return getattr(_local_storage, "current_tier", None)
+
+def set_current_tier(tier: Optional[str]) -> None:
+ """Sets the current tier in thread-local storage."""
+ _local_storage.current_tier = tier
+
 # Increased to allow thorough code exploration before forcing a summary
 MAX_TOOL_ROUNDS: int = 10
 
@@ -129,7 +137,6 @@ _comms_log: list[dict[str, Any]] = []
 COMMS_CLAMP_CHARS: int = 300
 
 def _append_comms(direction: str, kind: str, payload: dict[str, Any]) -> None:
- global current_tier
  entry: dict[str, Any] = {
   "ts":          datetime.datetime.now().strftime("%H:%M:%S"),
   "direction":   direction,
@@ -137,7 +144,7 @@ def _append_comms(direction: str, kind: str, payload: dict[str, Any]) -> None:
   "provider":    _provider,
   "model":       _model,
   "payload":     payload,
-  "source_tier": current_tier,
+  "source_tier": get_current_tier(),
  }
  _comms_log.append(entry)
  if comms_log_callback is not None:
@@ -1231,7 +1238,7 @@ def _send_anthropic(md_content: str, user_message: str, base_dir: str, file_item
      tool_executed = True
     
     if not tool_executed:
-     if name and name in mcp_client.TOOL_NAMES:
+     if b_name and b_name in mcp_client.TOOL_NAMES:
 
       _append_comms("OUT", "tool_call", {"name": b_name, "id": b_id, "args": b_input})
       if b_name in mcp_client.MUTATING_TOOLS and pre_tool_callback:
diff --git a/src/app_controller.py b/src/app_controller.py
index 6f11b6b..63f010b 100644
--- a/src/app_controller.py
+++ b/src/app_controller.py
@@ -851,7 +851,7 @@ class AppController:
       self._api_event_queue.append({"type": "response", "payload": payload})
  def _handle_request_event(self, event: events.UserRequestEvent) -> None:
   """Processes a UserRequestEvent by calling the AI client."""
-  ai_client.current_tier = None # Ensure main discussion is untagged
+  ai_client.set_current_tier(None) # Ensure main discussion is untagged
   if self.ui_auto_add_history:
    with self._pending_history_adds_lock:
     self._pending_history_adds.append({
@@ -935,7 +935,7 @@ class AppController:
 
  def _on_tool_log(self, script: str, result: str) -> None:
   session_logger.log_tool_call(script, result, None)
-  source_tier = ai_client.current_tier
+  source_tier = ai_client.get_current_tier()
   with self._pending_tool_calls_lock:
    self._pending_tool_calls.append({"script": script, "result": result, "ts": time.time(), "source_tier": source_tier})
 
diff --git a/src/conductor_tech_lead.py b/src/conductor_tech_lead.py
index 76804fd..680e3cd 100644
--- a/src/conductor_tech_lead.py
+++ b/src/conductor_tech_lead.py
@@ -20,7 +20,7 @@ def generate_tickets(track_brief: str, module_skeletons: str) -> list[dict[str,
  # Set custom system prompt for this call
  old_system_prompt = ai_client._custom_system_prompt
  ai_client.set_custom_system_prompt(system_prompt or "")
- ai_client.current_tier = "Tier 2"
+ ai_client.set_current_tier("Tier 2")
  last_error = None
  try:
   for _ in range(3):
@@ -53,7 +53,7 @@ def generate_tickets(track_brief: str, module_skeletons: str) -> list[dict[str,
  finally:
  # Restore old system prompt and clear tier tag
   ai_client.set_custom_system_prompt(old_system_prompt or "")
-  ai_client.current_tier = None
+  ai_client.set_current_tier(None)
 
 from src.dag_engine import TrackDAG
 from src.models import Ticket
diff --git a/src/multi_agent_conductor.py b/src/multi_agent_conductor.py
index 7be037c..49f309d 100644
--- a/src/multi_agent_conductor.py
+++ b/src/multi_agent_conductor.py
@@ -300,7 +300,7 @@ def run_worker_lifecycle(ticket: Ticket, context: WorkerContext, context_files:
    old_comms_cb(entry)
 
  ai_client.comms_log_callback = worker_comms_callback
- ai_client.current_tier = "Tier 3"
+ ai_client.set_current_tier("Tier 3")
  try:
   comms_baseline = len(ai_client.get_comms_log())
   response = ai_client.send(
@@ -313,7 +313,7 @@ def run_worker_lifecycle(ticket: Ticket, context: WorkerContext, context_files:
   )
  finally:
   ai_client.comms_log_callback = old_comms_cb
-  ai_client.current_tier = None
+  ai_client.set_current_tier(None)
  if event_queue:
   # Push via "response" event type — _process_event_queue wraps this
   # as {"action": "handle_ai_response", "payload": ...} for the GUI.
diff --git a/tests/test_ai_client_concurrency.py b/tests/test_ai_client_concurrency.py
new file mode 100644
index 0000000..ec83e33
--- /dev/null
+++ b/tests/test_ai_client_concurrency.py
@@ -0,0 +1,39 @@
+import threading
+from src import ai_client
+
+def test_ai_client_tier_isolation():
+ original_append = ai_client._append_comms
+ captured_logs = []
+ def intercepted_append(direction, kind, payload):
+  captured_logs.append({
+   'thread_name': threading.current_thread().name,
+   'source_tier': ai_client.get_current_tier()
+  })
+  original_append(direction, kind, payload)
+ ai_client._append_comms = intercepted_append
+ ai_client.clear_comms_log()
+ barrier = threading.Barrier(2)
+ def run_t1():
+  ai_client.set_current_tier('Tier 3')
+  barrier.wait()
+  ai_client._append_comms('OUT', 'test', {})
+ def run_t2():
+  ai_client.set_current_tier('Tier 4')
+  barrier.wait()
+  ai_client._append_comms('OUT', 'test', {})
+ t1 = threading.Thread(target=run_t1, name='T1')
+ t2 = threading.Thread(target=run_t2, name='T2')
+ t1.start()
+ t2.start()
+ t1.join()
+ t2.join()
+ try:
+  log_t1 = next(log for log in captured_logs if log['thread_name'] == 'T1')
+  log_t2 = next(log for log in captured_logs if log['thread_name'] == 'T2')
+  assert log_t1['source_tier'] == 'Tier 3'
+  assert log_t2['source_tier'] == 'Tier 4'
+ finally:
+  ai_client._append_comms = original_append
+
+if __name__ == "__main__":
+ test_ai_client_tier_isolation()
diff --git a/tests/test_mma_agent_focus_phase1.py b/tests/test_mma_agent_focus_phase1.py
index cb2f2eb..7c608ed 100644
--- a/tests/test_mma_agent_focus_phase1.py
+++ b/tests/test_mma_agent_focus_phase1.py
@@ -7,15 +7,14 @@ state when logging comms and tools.
 from src import ai_client
 
 def reset_tier():
- ai_client.current_tier = None
+ ai_client.set_current_tier(None)
  yield
- ai_client.current_tier = None
+ ai_client.set_current_tier(None)
 
-def test_current_tier_variable_exists() -> None:
- """ai_client must expose a module-level current_tier variable."""
- assert hasattr(ai_client, "current_tier")
- # current_tier might be None or a default
- pass
+def test_get_current_tier_exists() -> None:
+ """ai_client must expose a get_current_tier function."""
+ assert hasattr(ai_client, "get_current_tier")
+ assert callable(ai_client.get_current_tier)
 
 def test_append_comms_has_source_tier_key() -> None:
  """Dict entries in comms log must have a 'source_tier' key."""
@@ -30,7 +29,7 @@ def test_append_comms_has_source_tier_key() -> None:
 def test_append_comms_source_tier_none_when_unset() -> None:
  """When current_tier is None, source_tier in log must be None."""
  ai_client.reset_session()
- ai_client.current_tier = None
+ ai_client.set_current_tier(None)
  ai_client._append_comms("OUT", "request", {"msg": "hello"})
  
  log = ai_client.get_comms_log()
@@ -39,22 +38,22 @@ def test_append_comms_source_tier_none_when_unset() -> None:
 def test_append_comms_source_tier_set_when_current_tier_set() -> None:
  """When current_tier is 'Tier 1', source_tier in log must be 'Tier 1'."""
  ai_client.reset_session()
- ai_client.current_tier = "Tier 1"
+ ai_client.set_current_tier("Tier 1")
  ai_client._append_comms("OUT", "request", {"msg": "hello"})
  
  log = ai_client.get_comms_log()
  assert log[-1]["source_tier"] == "Tier 1"
- ai_client.current_tier = None
+ ai_client.set_current_tier(None)
 
 def test_append_comms_source_tier_tier2() -> None:
  """When current_tier is 'Tier 2', source_tier in log must be 'Tier 2'."""
  ai_client.reset_session()
- ai_client.current_tier = "Tier 2"
+ ai_client.set_current_tier("Tier 2")
  ai_client._append_comms("OUT", "request", {"msg": "hello"})
  
  log = ai_client.get_comms_log()
  assert log[-1]["source_tier"] == "Tier 2"
- ai_client.current_tier = None
+ ai_client.set_current_tier(None)
 
 def test_append_tool_log_stores_dict(app_instance) -> None:
  """App._append_tool_log must store a dict in self._tool_log."""
diff --git a/tests/test_token_usage.py b/tests/test_token_usage.py
index 24c3371..f627fea 100644
--- a/tests/test_token_usage.py
+++ b/tests/test_token_usage.py
@@ -9,6 +9,7 @@ from src import ai_client
 
 def test_token_usage_tracking() -> None:
  ai_client.reset_session()
+ ai_client.clear_comms_log()
  with patch("src.ai_client._ensure_gemini_client"), \
  patch("src.ai_client._gemini_client") as mock_client:
   mock_chat = MagicMock()