Add benchmark results and tests for LSP graph builder and staged search

- Introduced a new benchmark results file for performance comparison on 2026-02-09.
- Added a test for LspGraphBuilder to ensure it does not expand nodes at maximum depth.
- Created a test for the staged search pipeline to validate fallback behavior when stage 1 returns empty results.

ccw/src/core/services/cli-session-audit.ts

@@ -0,0 +1,39 @@
+import { existsSync, mkdirSync, appendFileSync } from 'fs';
+import path from 'path';
+
+export type CliSessionAuditEventType =
+  | 'session_created'
+  | 'session_closed'
+  | 'session_send'
+  | 'session_execute'
+  | 'session_resize'
+  | 'session_share_created'
+  | 'session_idle_reaped';
+
+export interface CliSessionAuditEvent {
+  type: CliSessionAuditEventType;
+  timestamp: string;
+  projectRoot: string;
+  sessionKey?: string;
+  tool?: string;
+  resumeKey?: string;
+  workingDir?: string;
+  ip?: string;
+  userAgent?: string;
+  details?: Record<string, unknown>;
+}
+
+function auditFilePath(projectRoot: string): string {
+  return path.join(projectRoot, '.workflow', 'audit', 'cli-sessions.jsonl');
+}
+
+export function appendCliSessionAudit(event: CliSessionAuditEvent): void {
+  try {
+    const filePath = auditFilePath(event.projectRoot);
+    const dir = path.dirname(filePath);
+    if (!existsSync(dir)) mkdirSync(dir, { recursive: true });
+    appendFileSync(filePath, JSON.stringify(event) + '\n', { encoding: 'utf8' });
+  } catch {
+    // Best-effort: never fail API requests due to audit write errors.
+  }
+}