feat(ai_client): isolation of current_tier using threading.local() for parallel agent safety

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**

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.