Implement inline commenting in diff view

**Complete Comment System: Diff View → LLM Feedback**

**Implementation:**
- Added comment callback mechanism to SyntheticPRProvider
- Modified handleCommentSubmission to extract file path and line number
- Added handleCommentFeedback method to DaemonClient
- Wired up comment submission to feedback system

**Flow:**
1. User adds comment in diff view using VSCode comment UI
2. Comment appears in thread (existing behavior)
3. Comment details sent as feedback to LLM with file path and line number
4. Tree view clears to show completion
5. LLM receives structured comment feedback

**Benefits:**
- **Line-specific comments** - Comments tied to exact file and line
- **Native VSCode UI** - Uses built-in comment system
- **Complete feedback loop** - Comments flow back to LLM for response
- **Clean integration** - Works with existing review system

**Result:** Users can now add meaningful comments on specific lines of code!

Author: nikomatsakis

extension/src/extension.ts

@@ -475,6 +475,36 @@ class DaemonClient implements vscode.Disposable {
         };
     }
 
+    /**
+     * Handle comment feedback from diff view
+     */
+    public handleCommentFeedback(comment: string, filePath: string, lineNumber: number): void {
+        const reviewId = this.currentReviewId;
+        if (!reviewId) {
+            vscode.window.showErrorMessage('No active review found');
+            return;
+        }
+
+        const resolver = this.pendingFeedbackResolvers.get(reviewId);
+        if (!resolver) {
+            vscode.window.showErrorMessage('No pending feedback request found');
+            return;
+        }
+
+        // Resolve with comment feedback
+        resolver({
+            feedback_type: 'comment',
+            review_id: reviewId,
+            comment_text: comment,
+            file_path: filePath,
+            line_number: lineNumber
+        });
+
+        // Clear tree view and cleanup
+        this.syntheticPRProvider.clearPR();
+        this.pendingFeedbackResolvers.delete(reviewId);
+    }
+
     /**
      * Handle review action from tree view button click
      */
@@ -775,6 +805,11 @@ export function activate(context: vscode.ExtensionContext) {
     const daemonClient = new DaemonClient(context, reviewProvider, outputChannel, syntheticPRProvider);
     daemonClient.start();
 
+    // Set up comment callback to send comments as feedback
+    syntheticPRProvider.setCommentCallback((comment: string, filePath: string, lineNumber: number) => {
+        daemonClient.handleCommentFeedback(comment, filePath, lineNumber);
+    });
+
     // 💡: Set up universal selection detection for interactive code review
     setupSelectionDetection(context, outputChannel, daemonClient);
 

extension/src/syntheticPRProvider.ts

@@ -68,6 +68,7 @@ export class SyntheticPRProvider implements vscode.Disposable {
     private treeProvider: SyntheticPRTreeProvider;
     private diffContentProvider: DialecticDiffContentProvider;
     private currentPR: SyntheticPRData | null = null;
+    private onCommentCallback?: (comment: string, filePath: string, lineNumber: number) => void;
 
     constructor(private context: vscode.ExtensionContext) {
         // Create diff content provider for virtual diff content
@@ -455,6 +456,24 @@ export class SyntheticPRProvider implements vscode.Disposable {
 
         // Ensure the thread can accept more replies
         reply.thread.canReply = true;
+
+        // Send comment as feedback to LLM
+        if (this.onCommentCallback && reply.thread.range) {
+            const uri = reply.thread.uri;
+            const lineNumber = reply.thread.range.start.line + 1; // Convert to 1-based
+            const filePath = uri.scheme === 'dialectic-diff' ? 
+                uri.path.replace('/diff/', '') : // Extract file path from diff URI
+                vscode.workspace.asRelativePath(uri);
+            
+            this.onCommentCallback(reply.text, filePath, lineNumber);
+        }
+    }
+
+    /**
+     * Set callback for when user submits a comment
+     */
+    setCommentCallback(callback: (comment: string, filePath: string, lineNumber: number) => void): void {
+        this.onCommentCallback = callback;
     }
 
     /**