feat: Add threaded review comments + agent comment responses

Introduces GitHub-style threaded comments via parentCommentId self-reference.
Users and agents can reply within comment threads, and review agents receive
comment IDs so they can post targeted responses via comment-responses.json.

- Migration 0032: parentCommentId column + index on review_comments
- Repository: createReply() copies parent context, default author 'you' → 'user'
- tRPC: replyToReviewComment procedure, requestPhaseChanges passes threaded comments
- Orchestrator: formats [comment:ID] tags with full reply threads in task description
- Agent IO: readCommentResponses() reads .cw/output/comment-responses.json
- OutputHandler: processes agent comment responses (creates replies, resolves threads)
- Execute prompt: conditional <review_comments> block when task has [comment:] markers
- Frontend: CommentThread renders root+replies with agent-specific styling + reply form
- Sidebar/ReviewTab: root-only comment counts, reply mutation plumbing through DiffViewer chain

docs/dispatch-events.md

@@ -123,5 +123,5 @@ Multiple rapid events (e.g. several `phase:queued` from `queueAllPhases`) are co
 
 - **YOLO**: phase completes → auto-merge → auto-dispatch next phase → auto-dispatch tasks
 - **review_per_phase**: phase completes → set `pending_review` → STOP. User approves → `approveAndMergePhase()` → merge → dispatch next phase → dispatch tasks
-- **request-changes (phase)**: phase `pending_review` → user requests changes → creates revision task (category=`'review'`, dedup guard skips if active review exists) → phase reset to `in_progress` → agent fixes → phase returns to `pending_review`
+- **request-changes (phase)**: phase `pending_review` → user requests changes → creates revision task (category=`'review'`, dedup guard skips if active review exists) with threaded comments (`[comment:ID]` tags + reply threads) → phase reset to `in_progress` → agent reads comments, fixes code, writes `.cw/output/comment-responses.json` → OutputHandler creates reply comments and optionally resolves threads → phase returns to `pending_review`
 - **request-changes (initiative)**: initiative `pending_review` → user requests changes → creates/reuses "Finalization" phase → creates review task → initiative reset to `active` → agent fixes → initiative returns to `pending_review`

docs/frontend.md

@@ -111,10 +111,11 @@ The initiative detail page has three tabs managed via local state (not URL param
 ### Review Components (`src/components/review/`)
 | Component | Purpose |
 |-----------|---------|
-| `ReviewTab` | Review tab container — orchestrates header, diff, sidebar, and preview. Phase-level review has inline comments + Request Changes; initiative-level review has Request Changes (summary prompt) + Push Branch / Merge & Push |
+| `ReviewTab` | Review tab container — orchestrates header, diff, sidebar, and preview. Phase-level review has threaded inline comments (with reply support) + Request Changes; initiative-level review has Request Changes (summary prompt) + Push Branch / Merge & Push |
 | `ReviewHeader` | Consolidated toolbar: phase selector pills, branch info, stats, preview controls, approve/reject actions |
-| `ReviewSidebar` | VSCode-style icon strip (Files/Commits views) with file list, comment counts, and commit navigation |
-| `DiffViewer` | Unified diff renderer with inline comments |
+| `ReviewSidebar` | VSCode-style icon strip (Files/Commits views) with file list, root-only comment counts, and commit navigation |
+| `DiffViewer` | Unified diff renderer with threaded inline comments (root + reply threads) |
+| `CommentThread` | Renders root comment with resolve/reopen + nested reply threads (agent replies styled with primary border). Inline reply form |
 | `PreviewPanel` | Docker preview status: building/running/failed with start/stop (legacy, now integrated into ReviewHeader) |
 | `ProposalCard` | Individual proposal display |
 

docs/server-api.md

@@ -116,11 +116,12 @@ Each procedure uses `require*Repository(ctx)` helpers that throw `TRPCError(INTE
 | getPhaseReviewCommits | query | List commits between initiative and phase branch |
 | getCommitDiff | query | Diff for a single commit (by hash) in a phase |
 | approvePhaseReview | mutation | Approve and merge phase branch |
-| requestPhaseChanges | mutation | Request changes: creates revision task from unresolved comments (dedup guard skips if active review exists), resets phase to in_progress |
-| listReviewComments | query | List review comments by phaseId |
+| requestPhaseChanges | mutation | Request changes: creates revision task from unresolved threaded comments (with `[comment:ID]` tags and reply threads), resets phase to in_progress |
+| listReviewComments | query | List review comments by phaseId (flat list including replies, frontend groups by parentCommentId) |
 | createReviewComment | mutation | Create inline review comment on diff |
 | resolveReviewComment | mutation | Mark review comment as resolved |
 | unresolveReviewComment | mutation | Mark review comment as unresolved |
+| replyToReviewComment | mutation | Create a threaded reply to an existing review comment (copies parent's phaseId/filePath/lineNumber) |
 
 ### Phase Dispatch
 | Procedure | Type | Description |