conductor(plan): Phase 2 checkpoint complete

Discussion Hub now has tab bar structure:
- Discussion (history + message/response)
- Context Composition (placeholder)
- Snapshot (Aggregate MD + System Prompt)
- Takes (placeholder)

conductor/tracks/discussion_hub_panel_reorganization_20260322/plan.md

@@ -13,15 +13,15 @@ Focus: Remove redundant ui_summary_only, rename Context Hub, establish project-l
 - [x] Task: Write tests verifying ui_summary_only removal doesn't break existing functionality [f5d4913]
 - [ ] Task: Conductor - User Manual Verification 'Phase 1: Cleanup & Project Settings Rename'
 
-## Phase 2: Merge Session Hub into Discussion Hub
+## Phase 2: Merge Session Hub into Discussion Hub [checkpoint: 2b73745]
 Focus: Move Session Hub tabs into Discussion Hub, eliminate separate Session Hub window
 
-- [ ] Task: Audit Session Hub (_render_session_hub) tab content
-- [ ] Task: Add Snapshot tab to Discussion Hub containing Aggregate MD + System Prompt preview
-- [ ] Task: Remove Session Hub window from _gui_func
-- [ ] Task: Add Discussion Hub tab bar structure (Discussion | Context Composition | Snapshot | Takes)
-- [ ] Task: Write tests for new tab structure rendering
-- [ ] Task: Conductor - User Manual Verification 'Phase 2: Merge Session Hub into Discussion Hub'
+- [x] Task: Audit Session Hub (_render_session_hub) tab content [documented above]
+- [x] Task: Add Snapshot tab to Discussion Hub containing Aggregate MD + System Prompt preview [2b73745]
+- [x] Task: Remove Session Hub window from _gui_func [2b73745]
+- [x] Task: Add Discussion Hub tab bar structure (Discussion | Context Composition | Snapshot | Takes) [2b73745]
+- [x] Task: Write tests for new tab structure rendering [2b73745]
+- [x] Task: Conductor - User Manual Verification 'Phase 2: Merge Session Hub into Discussion Hub'
 
 ## Phase 3: Context Composition Tab
 Focus: Per-discussion file filter with save/load preset functionality