diff --git a/conductor/tracks/python_style_refactor_20260227/plan.md b/conductor/tracks/python_style_refactor_20260227/plan.md
index b60929c..65a386c 100644
--- a/conductor/tracks/python_style_refactor_20260227/plan.md
+++ b/conductor/tracks/python_style_refactor_20260227/plan.md
@@ -40,7 +40,7 @@
 - [x] Task: Conductor - User Manual Verification 'Phase 5: Ultra-Compact Indentation Refactor'
 
 
-## Phase 6: Test Suite Stabilization (High-Signal Reporting)
+## Phase 6: Test Suite Stabilization (High-Signal Reporting) [checkpoint: 3b96b67]
 - [x] Task: Conductor - Resolve API/Method name drift (e.g., `run_linear` -> `run` in ConductorEngine).
     - **Requirement:** Implement "Before vs After" state tables in `logs/test/unique_signature/<script_name>.txt`.
 - [x] Task: Conductor - Fix `ai_style_formatter.py` test expectations for ultra-compact style.
@@ -49,7 +49,8 @@
     - **Requirement:** Log expected vs actual PowerShell output mappings in `logs/test/unique_signature/test_tier4_interceptor.txt`.
 - [x] Task: Conductor - Investigate and stabilize `live_gui` test environment collection/startup. 173ea96
     - **Requirement:** Log comprehensive environment telemetry (Before/After/Delta) in `logs/test/unique_signature/live_gui_diag.txt`.
-- [ ] Task: Conductor - User Manual Verification 'Phase 6: Test Suite Stabilization'
+- [x] Task: Conductor - User Manual Verification 'Phase 6: Test Suite Stabilization'
+