perf: implement phase 1-3 performance optimizations

Add implementation plans and code structure analysis for a 3-phase
performance optimization effort. Refactor core modules to reduce
timer overhead, consolidate regex usage, extract exec timeout config,
add debouncer utility, and streamline server/schema validation.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

test/hooks-config.test.ts

@@ -126,7 +126,10 @@ describe('writeHooksConfig', () => {
     writeHooksConfig(testDir);
     const settingsPath = join(testDir, '.claude', 'settings.local.json');
     const content = readFileSync(settingsPath, 'utf-8');
-    expect(() => JSON.parse(content)).not.toThrow();
+    const parsed = JSON.parse(content);
+    expect(parsed).toHaveProperty('hooks');
+    expect(parsed.hooks).toHaveProperty('Notification');
+    expect(parsed.hooks).toHaveProperty('Stop');
   });
 
   it('should include hooks config in output', () => {

test/image-watcher.test.ts

@@ -121,6 +121,7 @@ describe('ImageWatcher', () => {
 
     it('should be safe to call for non-watched session', () => {
       expect(() => watcher.unwatchSession('nonexistent')).not.toThrow();
+      expect(watcher.getWatchedSessions()).toHaveLength(0);
     });
 
     it('should clear pending debounce timers for the session', () => {

test/session-manager.test.ts

@@ -214,6 +214,7 @@ describe('SessionManager', () => {
 
     it('should handle non-existent session gracefully', async () => {
       await expect(manager.stopSession('non-existent')).resolves.not.toThrow();
+      expect(manager.getSessionCount()).toBe(0);
     });
 
     it('should update stored session to stopped', async () => {

test/task-queue.test.ts

@@ -536,9 +536,11 @@ describe('circular dependency detection', () => {
 
   it('should allow dependencies on non-existent tasks (just unsatisfied, not a cycle)', () => {
     // Dependencies on non-existent tasks are valid - they just won't be satisfied
-    expect(() => {
-      queue.addTask({ prompt: 'Task D', dependencies: ['non-existent-id'] });
-    }).not.toThrow();
+    const task = queue.addTask({ prompt: 'Task D', dependencies: ['non-existent-id'] });
+    expect(queue.getAllTasks()).toHaveLength(1);
+    expect(task.dependencies).toEqual(['non-existent-id']);
+    // Task is blocked by unsatisfied dependency, so next() should return null
+    expect(queue.next()).toBeNull();
   });
 
   it('should detect self-dependency when task references itself', () => {

test/task-tracker.test.ts

@@ -564,14 +564,18 @@ describe('TaskTracker', () => {
   describe('Edge Cases', () => {
     it('should handle null message', () => {
       expect(() => tracker.processMessage(null)).not.toThrow();
+      expect(tracker.getAllTasks().size).toBe(0);
+      expect(tracker.getRunningCount()).toBe(0);
     });
 
     it('should handle message without content', () => {
       expect(() => tracker.processMessage({ message: {} })).not.toThrow();
+      expect(tracker.getAllTasks().size).toBe(0);
     });
 
     it('should handle empty content array', () => {
       expect(() => tracker.processMessage({ message: { content: [] } })).not.toThrow();
+      expect(tracker.getAllTasks().size).toBe(0);
     });
 
     it('should handle tool_result for unknown task', () => {
@@ -587,11 +591,15 @@ describe('TaskTracker', () => {
           },
         });
       }).not.toThrow();
+      expect(tracker.getTask('unknown-task')).toBeUndefined();
+      expect(tracker.getAllTasks().size).toBe(0);
     });
 
     it('should handle empty terminal output', () => {
       expect(() => tracker.processTerminalOutput('')).not.toThrow();
       expect(() => tracker.processTerminalOutput('   ')).not.toThrow();
+      expect(tracker.getAllTasks().size).toBe(0);
+      expect(tracker.getRunningCount()).toBe(0);
     });
   });