feat: search query utilities and multi-signal scoring

- Add src/search/query-utils.ts with extractSearchTerms, scorePathRelevance,
  kindBonus, detectApiIntent, inferRouteDirectories
- Add multi-signal scoring to searchNodes (kind bonus + path relevance)
- Improve FTS query sanitization (strip :^ chars, filter boolean operators)
- Add comprehensive search tests

__tests__/search.test.ts

@@ -0,0 +1,214 @@
+/**
+ * Search Query Utilities Tests
+ *
+ * Tests multi-signal scoring, kind bonuses, path relevance, and API intent detection.
+ */
+
+import { describe, it, expect } from 'vitest';
+import {
+  extractSearchTerms,
+  scorePathRelevance,
+  kindBonus,
+  detectApiIntent,
+  inferRouteDirectories,
+  STOP_WORDS,
+} from '../src/search/query-utils';
+
+describe('Search Query Utilities', () => {
+  describe('extractSearchTerms', () => {
+    it('should extract meaningful terms from a query', () => {
+      const terms = extractSearchTerms('find the login handler');
+      expect(terms).toContain('login');
+      expect(terms).toContain('handler');
+      // 'find' and 'the' are stop words
+      expect(terms).not.toContain('find');
+      expect(terms).not.toContain('the');
+    });
+
+    it('should filter stop words', () => {
+      const terms = extractSearchTerms('how does the authentication work');
+      expect(terms).not.toContain('how');
+      expect(terms).not.toContain('does');
+      expect(terms).not.toContain('the');
+      expect(terms).toContain('authentication');
+      expect(terms).toContain('work');
+    });
+
+    it('should handle camelCase by lowercasing', () => {
+      const terms = extractSearchTerms('UserService');
+      expect(terms).toContain('userservice');
+    });
+
+    it('should strip punctuation', () => {
+      const terms = extractSearchTerms('payment.process()');
+      expect(terms).toContain('payment');
+      expect(terms).toContain('process');
+    });
+
+    it('should return empty for all stop words', () => {
+      const terms = extractSearchTerms('how do I get the');
+      expect(terms).toHaveLength(0);
+    });
+
+    it('should filter single-character terms', () => {
+      const terms = extractSearchTerms('a b c auth');
+      expect(terms).toEqual(['auth']);
+    });
+  });
+
+  describe('scorePathRelevance', () => {
+    it('should score filename matches highest', () => {
+      const score = scorePathRelevance('src/auth/login.ts', 'login');
+      expect(score).toBeGreaterThanOrEqual(10);
+    });
+
+    it('should score directory matches', () => {
+      const score = scorePathRelevance('src/auth/index.ts', 'auth');
+      expect(score).toBeGreaterThanOrEqual(5);
+    });
+
+    it('should return 0 for unrelated paths', () => {
+      const score = scorePathRelevance('src/utils/format.ts', 'payment');
+      expect(score).toBe(0);
+    });
+
+    it('should accumulate scores for multiple matching terms', () => {
+      const score = scorePathRelevance('src/auth/login.ts', 'auth login');
+      // Both 'auth' (dir match) and 'login' (filename match)
+      expect(score).toBeGreaterThanOrEqual(15);
+    });
+
+    it('should return 0 for empty query terms', () => {
+      const score = scorePathRelevance('src/auth/login.ts', 'the a an');
+      expect(score).toBe(0);
+    });
+  });
+
+  describe('kindBonus', () => {
+    it('should give functions and methods highest bonus', () => {
+      expect(kindBonus('function')).toBe(10);
+      expect(kindBonus('method')).toBe(10);
+    });
+
+    it('should rank functions > classes > variables > imports', () => {
+      expect(kindBonus('function')).toBeGreaterThan(kindBonus('class'));
+      expect(kindBonus('class')).toBeGreaterThan(kindBonus('variable'));
+      expect(kindBonus('variable')).toBeGreaterThan(kindBonus('import'));
+    });
+
+    it('should give routes high priority', () => {
+      expect(kindBonus('route')).toBeGreaterThanOrEqual(9);
+    });
+
+    it('should give components high priority', () => {
+      expect(kindBonus('component')).toBeGreaterThanOrEqual(8);
+    });
+
+    it('should return 0 for parameter and file kinds', () => {
+      expect(kindBonus('parameter')).toBe(0);
+      expect(kindBonus('file')).toBe(0);
+    });
+
+    it('should return 0 for unknown kinds', () => {
+      expect(kindBonus('unknown_kind' as any)).toBe(0);
+    });
+  });
+
+  describe('detectApiIntent', () => {
+    it('should detect API-related queries', () => {
+      expect(detectApiIntent('find the API endpoint for users')).toBe(true);
+      expect(detectApiIntent('where is the login route')).toBe(true);
+      expect(detectApiIntent('show me the request handler')).toBe(true);
+    });
+
+    it('should detect HTTP method patterns', () => {
+      expect(detectApiIntent('GET /api/users')).toBe(true);
+      expect(detectApiIntent('post /users/create')).toBe(true);
+    });
+
+    it('should detect REST and GraphQL', () => {
+      expect(detectApiIntent('REST API for payments')).toBe(true);
+      expect(detectApiIntent('GraphQL resolver for orders')).toBe(true);
+    });
+
+    it('should not detect non-API queries', () => {
+      expect(detectApiIntent('fix the login bug')).toBe(false);
+      expect(detectApiIntent('add dark mode support')).toBe(false);
+    });
+
+    it('should detect controller and middleware mentions', () => {
+      expect(detectApiIntent('find the auth controller')).toBe(true);
+      expect(detectApiIntent('CORS middleware configuration')).toBe(true);
+    });
+  });
+
+  describe('inferRouteDirectories', () => {
+    it('should detect route directories', () => {
+      const files = [
+        'src/routes/auth.ts',
+        'src/routes/users.ts',
+        'src/utils/format.ts',
+      ];
+      const dirs = inferRouteDirectories(files);
+      expect(dirs).toBeDefined();
+      if (dirs) {
+        expect(dirs.some(d => d.includes('route'))).toBe(true);
+      }
+    });
+
+    it('should detect controller directories', () => {
+      const files = [
+        'src/controllers/AuthController.ts',
+        'src/models/User.ts',
+      ];
+      const dirs = inferRouteDirectories(files);
+      expect(dirs).toBeDefined();
+      if (dirs) {
+        expect(dirs.some(d => d.includes('controller'))).toBe(true);
+      }
+    });
+
+    it('should detect api directories', () => {
+      const files = [
+        'src/api/v1/users.ts',
+        'src/api/v1/orders.ts',
+      ];
+      const dirs = inferRouteDirectories(files);
+      expect(dirs).toBeDefined();
+      if (dirs) {
+        expect(dirs.some(d => d.includes('api'))).toBe(true);
+      }
+    });
+
+    it('should return undefined when no route dirs found', () => {
+      const files = [
+        'src/utils/format.ts',
+        'src/models/User.ts',
+        'src/index.ts',
+      ];
+      const dirs = inferRouteDirectories(files);
+      expect(dirs).toBeUndefined();
+    });
+  });
+
+  describe('STOP_WORDS', () => {
+    it('should contain common English stop words', () => {
+      expect(STOP_WORDS.has('the')).toBe(true);
+      expect(STOP_WORDS.has('and')).toBe(true);
+      expect(STOP_WORDS.has('or')).toBe(true);
+    });
+
+    it('should contain action verbs used in queries', () => {
+      expect(STOP_WORDS.has('find')).toBe(true);
+      expect(STOP_WORDS.has('show')).toBe(true);
+      expect(STOP_WORDS.has('get')).toBe(true);
+      expect(STOP_WORDS.has('list')).toBe(true);
+    });
+
+    it('should not contain technical terms', () => {
+      expect(STOP_WORDS.has('function')).toBe(false);
+      expect(STOP_WORDS.has('class')).toBe(false);
+      expect(STOP_WORDS.has('auth')).toBe(false);
+    });
+  });
+});