diff --git a/services/platform-service/src/modules/ai-diagnostics/clustering.test.ts b/services/platform-service/src/modules/ai-diagnostics/clustering.test.ts
new file mode 100644
index 00000000..53d6053a
--- /dev/null
+++ b/services/platform-service/src/modules/ai-diagnostics/clustering.test.ts
@@ -0,0 +1,189 @@
+import { describe, expect, it } from 'vitest';
+import {
+  runHDBSCAN,
+  runDBSCAN,
+  autoSelectParameters,
+  calculateClusterQuality,
+} from './clustering.js';
+
+// ── Helpers ──────────────────────────────────────────────────────
+
+function makePoint(id: string, embedding: number[], errorType = 'TypeError') {
+  return {
+    id,
+    embedding,
+    metadata: {
+      errorType,
+      messageTemplate: `Error in ${id}`,
+      stackSignature: `sig_${id}`,
+      productId: 'test',
+      firstSeenAt: new Date(Date.now() - Math.random() * 86400000).toISOString(),
+    },
+  };
+}
+
+function makeCluster(center: number[], spread: number, count: number, prefix: string) {
+  return Array.from({ length: count }, (_, i) =>
+    makePoint(
+      `${prefix}_${i}`,
+      center.map(c => c + (Math.random() - 0.5) * spread)
+    )
+  );
+}
+
+// ============================================================================
+// runHDBSCAN
+// ============================================================================
+
+describe('runHDBSCAN', () => {
+  it('returns all points as noise when fewer than minClusterSize', () => {
+    const points = [makePoint('a', [1, 0, 0]), makePoint('b', [0, 1, 0])];
+    const result = runHDBSCAN(points, { minClusterSize: 3 });
+    expect(result.clusters).toHaveLength(0);
+    expect(result.noise).toHaveLength(2);
+    expect(result.labels.get('a')).toBe(-1);
+  });
+
+  it('finds clusters in well-separated data', () => {
+    const clusterA = makeCluster([1, 0, 0], 0.01, 5, 'a');
+    const clusterB = makeCluster([0, 0, 1], 0.01, 5, 'b');
+    const points = [...clusterA, ...clusterB];
+
+    const result = runHDBSCAN(points, { minClusterSize: 3, minSamples: 2, metric: 'euclidean' });
+    expect(result.clusters.length).toBeGreaterThanOrEqual(1);
+    // Every point should get a label
+    expect(result.labels.size).toBe(points.length);
+  });
+
+  it('assigns centroids to clusters', () => {
+    const points = makeCluster([1, 1, 1], 0.01, 6, 'c');
+    const result = runHDBSCAN(points, { minClusterSize: 3, metric: 'euclidean' });
+    for (const cluster of result.clusters) {
+      expect(cluster.centroid.length).toBe(3);
+      // Centroid should be near [1,1,1]
+      for (const val of cluster.centroid) {
+        expect(val).toBeCloseTo(1, 0);
+      }
+    }
+  });
+
+  it('handles single-dimension embeddings', () => {
+    const points = [
+      makePoint('x1', [0.1]),
+      makePoint('x2', [0.2]),
+      makePoint('x3', [0.15]),
+      makePoint('x4', [0.9]),
+      makePoint('x5', [0.95]),
+      makePoint('x6', [0.88]),
+    ];
+    const result = runHDBSCAN(points, { minClusterSize: 2, minSamples: 1, metric: 'euclidean' });
+    expect(result.labels.size).toBe(6);
+  });
+});
+
+// ============================================================================
+// runDBSCAN
+// ============================================================================
+
+describe('runDBSCAN', () => {
+  it('finds dense clusters and marks outliers as noise', () => {
+    const cluster = makeCluster([0, 0], 0.05, 5, 'dense');
+    const outlier = makePoint('outlier', [10, 10]);
+    const points = [...cluster, outlier];
+
+    const result = runDBSCAN(points, { eps: 0.5, minPts: 2 });
+    expect(result.clusters.length).toBeGreaterThanOrEqual(1);
+    expect(result.labels.get('outlier')).toBe(-1);
+  });
+
+  it('returns no clusters when eps is too small', () => {
+    const points = makeCluster([0, 0], 1.0, 5, 'spread');
+    const result = runDBSCAN(points, { eps: 0.001, minPts: 3 });
+    expect(result.clusters).toHaveLength(0);
+    expect(result.noise).toHaveLength(5);
+  });
+
+  it('puts all points in one cluster when eps is large enough', () => {
+    const points = makeCluster([0, 0], 0.1, 6, 'tight');
+    const result = runDBSCAN(points, { eps: 100, minPts: 2 });
+    expect(result.clusters).toHaveLength(1);
+    expect(result.noise).toHaveLength(0);
+  });
+});
+
+// ============================================================================
+// autoSelectParameters
+// ============================================================================
+
+describe('autoSelectParameters', () => {
+  it('selects DBSCAN for very small datasets (<10)', () => {
+    const params = autoSelectParameters(5);
+    expect(params.algorithm).toBe('dbscan');
+  });
+
+  it('selects HDBSCAN with small minClusterSize for small datasets', () => {
+    const params = autoSelectParameters(25);
+    expect(params.algorithm).toBe('hdbscan');
+    expect(params.minClusterSize).toBe(2);
+  });
+
+  it('selects HDBSCAN with medium settings for medium datasets', () => {
+    const params = autoSelectParameters(100);
+    expect(params.algorithm).toBe('hdbscan');
+    expect(params.minClusterSize).toBe(3);
+    expect(params.metric).toBe('cosine');
+  });
+
+  it('selects HDBSCAN with larger settings for large datasets', () => {
+    const params = autoSelectParameters(1000);
+    expect(params.algorithm).toBe('hdbscan');
+    expect(params.minClusterSize).toBe(5);
+    expect(params.minSamples).toBe(3);
+  });
+});
+
+// ============================================================================
+// calculateClusterQuality
+// ============================================================================
+
+describe('calculateClusterQuality', () => {
+  it('returns metrics object with silhouetteScore', () => {
+    const points = [...makeCluster([0, 0], 0.01, 3, 'a'), ...makeCluster([5, 5], 0.01, 3, 'b')];
+    const labels = new Map<string, number>();
+    points.forEach((p, i) => labels.set(p.id, i < 3 ? 0 : 1));
+
+    const clusters = [
+      {
+        id: 'c0',
+        points: points.slice(0, 3),
+        centroid: [0, 0],
+        stability: 1,
+        density: 1,
+      },
+      {
+        id: 'c1',
+        points: points.slice(3),
+        centroid: [5, 5],
+        stability: 1,
+        density: 1,
+      },
+    ];
+
+    const quality = calculateClusterQuality(points, labels, clusters);
+    expect(quality).toHaveProperty('silhouetteScore');
+    expect(quality).toHaveProperty('daviesBouldinIndex');
+    expect(quality).toHaveProperty('calinskiHarabaszIndex');
+    // Well-separated clusters should have positive silhouette
+    expect(quality.silhouetteScore).toBeGreaterThan(0);
+  });
+
+  it('returns 0 silhouette when all points are noise', () => {
+    const points = [makePoint('n1', [0, 0]), makePoint('n2', [1, 1])];
+    const labels = new Map<string, number>([
+      ['n1', -1],
+      ['n2', -1],
+    ]);
+    const quality = calculateClusterQuality(points, labels, []);
+    expect(quality.silhouetteScore).toBe(0);
+  });
+});
diff --git a/services/platform-service/src/modules/ai-diagnostics/error-normalization.test.ts b/services/platform-service/src/modules/ai-diagnostics/error-normalization.test.ts
new file mode 100644
index 00000000..1edf5528
--- /dev/null
+++ b/services/platform-service/src/modules/ai-diagnostics/error-normalization.test.ts
@@ -0,0 +1,430 @@
+import { describe, expect, it } from 'vitest';
+import {
+  normalizeErrorMessage,
+  parseStackTrace,
+  normalizeStackFrames,
+  generateFingerprint,
+  levenshteinDistance,
+  calculateFingerprintSimilarity,
+  processErrorEvent,
+  updateClusterWithError,
+} from './error-normalization.js';
+import type { ErrorEvent, ErrorFingerprint, ErrorClusterDoc } from './types.js';
+
+// ============================================================================
+// normalizeErrorMessage
+// ============================================================================
+
+describe('normalizeErrorMessage', () => {
+  it('replaces UUIDs with <UUID>', () => {
+    const msg = 'Failed for user 550e8400-e29b-41d4-a716-446655440000';
+    expect(normalizeErrorMessage(msg)).toContain('<UUID>');
+    expect(normalizeErrorMessage(msg)).not.toContain('550e8400');
+  });
+
+  it('replaces MongoDB ObjectIds with <ID>', () => {
+    const msg = 'Document 507f1f77bcf86cd799439011 not found';
+    expect(normalizeErrorMessage(msg)).toContain('<ID>');
+  });
+
+  it('replaces email addresses with <EMAIL>', () => {
+    const msg = 'Login failed for alice@example.com';
+    expect(normalizeErrorMessage(msg)).toContain('<EMAIL>');
+    expect(normalizeErrorMessage(msg)).not.toContain('alice@example.com');
+  });
+
+  it('replaces IPv4 addresses with <IP>', () => {
+    const msg = 'Connection refused from 192.168.1.100';
+    expect(normalizeErrorMessage(msg)).toContain('<IP>');
+  });
+
+  it('replaces ISO timestamps with <DATE>', () => {
+    const msg = 'Error at 2026-03-21T12:30:45.123Z';
+    expect(normalizeErrorMessage(msg)).toContain('<DATE>');
+  });
+
+  it('replaces simple dates with <DATE>', () => {
+    const msg = 'Last seen on 03/21/2026';
+    expect(normalizeErrorMessage(msg)).toContain('<DATE>');
+  });
+
+  it('replaces user IDs with <USER_ID>', () => {
+    const msg = 'Cannot find user_12345';
+    expect(normalizeErrorMessage(msg)).toContain('<USER_ID>');
+  });
+
+  it('replaces long numbers with <NUM>', () => {
+    const msg = 'Record 12345678901 overflow';
+    expect(normalizeErrorMessage(msg)).toContain('<NUM>');
+  });
+
+  it('replaces URLs with <URL>', () => {
+    const msg = 'Fetch failed for https://api.example.com/v1/data';
+    expect(normalizeErrorMessage(msg)).toContain('<URL>');
+  });
+
+  it('normalizes file paths keeping filename', () => {
+    const msg = 'Error in /src/lib/server.ts';
+    const result = normalizeErrorMessage(msg);
+    expect(result).toContain('server.ts');
+  });
+
+  it('handles messages with multiple replaceable parts', () => {
+    const msg =
+      'User user_999 at 192.168.0.1 failed at 2026-01-01T00:00:00Z with id 550e8400-e29b-41d4-a716-446655440000';
+    const result = normalizeErrorMessage(msg);
+    expect(result).toContain('<USER_ID>');
+    expect(result).toContain('<IP>');
+    expect(result).toContain('<DATE>');
+    expect(result).toContain('<UUID>');
+  });
+
+  it('returns unchanged message if nothing to normalize', () => {
+    expect(normalizeErrorMessage('TypeError: cannot read property')).toBe(
+      'TypeError: cannot read property'
+    );
+  });
+});
+
+// ============================================================================
+// parseStackTrace
+// ============================================================================
+
+describe('parseStackTrace', () => {
+  it('parses JavaScript stack frames', () => {
+    const stack = `Error: something went wrong
+    at handleRequest (/app/src/server.ts:42:10)
+    at processTicksAndRejections (internal/process/task_queues.js:95:5)`;
+    const frames = parseStackTrace(stack);
+    expect(frames.length).toBeGreaterThanOrEqual(1);
+    expect(frames[0].function).toBe('handleRequest');
+    expect(frames[0].line).toBe(42);
+  });
+
+  it('parses async JavaScript stack frames', () => {
+    const stack = '    at async fetchData (/app/lib/api.ts:10:3)';
+    const frames = parseStackTrace(stack);
+    expect(frames.length).toBe(1);
+    expect(frames[0].function).toBe('fetchData');
+  });
+
+  it('parses Python stack frames', () => {
+    const stack = '  File "/app/main.py", line 25, in handle_request';
+    const frames = parseStackTrace(stack);
+    expect(frames.length).toBe(1);
+    expect(frames[0].function).toBe('handle_request');
+    expect(frames[0].line).toBe(25);
+  });
+
+  it('parses Java/Kotlin stack frames', () => {
+    const stack = '    at com.example.MyClass.doSomething(MyClass.java:55)';
+    const frames = parseStackTrace(stack);
+    expect(frames.length).toBe(1);
+    expect(frames[0].line).toBe(55);
+  });
+
+  it('returns empty array for empty input', () => {
+    expect(parseStackTrace('')).toEqual([]);
+  });
+
+  it('skips unparseable lines', () => {
+    const stack = `Error: boom
+This is not a stack frame
+Another line
+    at realFrame (/app/file.ts:1:1)`;
+    const frames = parseStackTrace(stack);
+    expect(frames.length).toBe(1);
+    expect(frames[0].function).toBe('realFrame');
+  });
+});
+
+// ============================================================================
+// normalizeStackFrames
+// ============================================================================
+
+describe('normalizeStackFrames', () => {
+  it('normalizes and joins frames', () => {
+    const frames = [
+      { function: 'handleRequest', file: '/app/server.ts', line: 42, column: 10 },
+      { function: 'processData', file: '/app/lib/data.ts', line: 15 },
+    ];
+    const result = normalizeStackFrames(frames);
+    expect(result).toContain('handleRequest@');
+    expect(result).toContain('|');
+    expect(result).toContain('processData@');
+  });
+
+  it('truncates to maxFrames', () => {
+    const frames = Array.from({ length: 20 }, (_, i) => ({
+      function: `fn${i}`,
+      file: `/app/f${i}.ts`,
+      line: i,
+    }));
+    const result = normalizeStackFrames(frames, 3);
+    expect(result.split('|').length).toBe(3);
+  });
+
+  it('handles empty frames', () => {
+    expect(normalizeStackFrames([])).toBe('');
+  });
+});
+
+// ============================================================================
+// generateFingerprint
+// ============================================================================
+
+describe('generateFingerprint', () => {
+  it('generates a SHA-256 hash', () => {
+    const result = generateFingerprint({
+      errorType: 'TypeError',
+      message: 'Cannot read property of null',
+    });
+    expect(result.hash).toMatch(/^[a-f0-9]{64}$/);
+  });
+
+  it('strips Error/Exception suffix from type', () => {
+    const result = generateFingerprint({
+      errorType: 'NullPointerException',
+      message: 'Null pointer',
+    });
+    expect(result.normalizedType).toBe('NullPointer');
+  });
+
+  it('normalizes the message', () => {
+    const result = generateFingerprint({
+      errorType: 'Error',
+      message: 'Failed for user user_123 at 192.168.1.1',
+    });
+    expect(result.normalizedMessage).toContain('<USER_ID>');
+    expect(result.normalizedMessage).toContain('<IP>');
+  });
+
+  it('extracts source location from stack trace', () => {
+    const result = generateFingerprint({
+      errorType: 'Error',
+      message: 'boom',
+      stackTrace: '    at myFunc (/app/src/handler.ts:10:5)',
+    });
+    expect(result.sourceLocation).toBeDefined();
+    expect(result.sourceLocation?.function).toBe('myFunc');
+    expect(result.sourceLocation?.line).toBe(10);
+  });
+
+  it('produces same hash for same normalized input', () => {
+    const a = generateFingerprint({
+      errorType: 'TypeError',
+      message: 'Cannot read property of null',
+    });
+    const b = generateFingerprint({
+      errorType: 'TypeError',
+      message: 'Cannot read property of null',
+    });
+    expect(a.hash).toBe(b.hash);
+  });
+
+  it('produces different hash for different inputs', () => {
+    const a = generateFingerprint({ errorType: 'TypeError', message: 'a' });
+    const b = generateFingerprint({ errorType: 'RangeError', message: 'b' });
+    expect(a.hash).not.toBe(b.hash);
+  });
+});
+
+// ============================================================================
+// levenshteinDistance
+// ============================================================================
+
+describe('levenshteinDistance', () => {
+  it('returns 0 for identical strings', () => {
+    expect(levenshteinDistance('abc', 'abc')).toBe(0);
+  });
+
+  it('returns correct distance for single edit', () => {
+    expect(levenshteinDistance('cat', 'bat')).toBe(1);
+  });
+
+  it('returns length of longer string when one is empty', () => {
+    expect(levenshteinDistance('', 'abc')).toBe(3);
+    expect(levenshteinDistance('abc', '')).toBe(3);
+  });
+
+  it('handles completely different strings', () => {
+    expect(levenshteinDistance('abc', 'xyz')).toBe(3);
+  });
+});
+
+// ============================================================================
+// calculateFingerprintSimilarity
+// ============================================================================
+
+describe('calculateFingerprintSimilarity', () => {
+  it('returns 1 for identical fingerprints', () => {
+    const fp = {
+      hash: 'abc',
+      normalizedType: 'Type',
+      normalizedMessage: 'msg',
+      stackSignature: 'sig',
+    };
+    expect(calculateFingerprintSimilarity(fp, fp)).toBeCloseTo(1, 1);
+  });
+
+  it('returns high score for same type and similar message', () => {
+    const a = {
+      hash: 'a',
+      normalizedType: 'TypeError',
+      normalizedMessage: 'Cannot read property x',
+      stackSignature: '',
+    };
+    const b = {
+      hash: 'b',
+      normalizedType: 'TypeError',
+      normalizedMessage: 'Cannot read property y',
+      stackSignature: '',
+    };
+    expect(calculateFingerprintSimilarity(a, b)).toBeGreaterThan(0.7);
+  });
+
+  it('returns low score for different types and messages', () => {
+    const a = {
+      hash: 'a',
+      normalizedType: 'TypeError',
+      normalizedMessage: 'null pointer',
+      stackSignature: '',
+    };
+    const b = {
+      hash: 'b',
+      normalizedType: 'RangeError',
+      normalizedMessage: 'stack overflow in recursive call',
+      stackSignature: '',
+    };
+    expect(calculateFingerprintSimilarity(a, b)).toBeLessThan(0.5);
+  });
+});
+
+// ============================================================================
+// processErrorEvent
+// ============================================================================
+
+describe('processErrorEvent', () => {
+  const baseEvent: ErrorEvent = {
+    id: 'ev_1',
+    productId: 'lysnrai',
+    errorType: 'TypeError',
+    message: 'Cannot read property of null',
+    timestamp: new Date().toISOString(),
+    platform: 'ios',
+    osVersion: '18.0',
+    appVersion: '1.2.0',
+  };
+
+  it('creates a new cluster when no existing fingerprints', () => {
+    const result = processErrorEvent(baseEvent);
+    expect(result.isNewCluster).toBe(true);
+    expect(result.clusterId).toMatch(/^ec_/);
+    expect(result.fingerprint.hash).toBeTruthy();
+  });
+
+  it('matches existing fingerprint when similarity >= 0.85', () => {
+    const fp = generateFingerprint({
+      errorType: baseEvent.errorType,
+      message: baseEvent.message,
+    });
+
+    const existing: ErrorFingerprint = {
+      id: 'ef_existing',
+      productId: 'lysnrai',
+      fingerprintHash: fp.hash,
+      errorType: fp.normalizedType,
+      messageTemplate: fp.normalizedMessage,
+      stackSignature: fp.stackSignature,
+      createdAt: new Date().toISOString(),
+      updatedAt: new Date().toISOString(),
+      occurrenceCount: 5,
+      uniqueUsers: 3,
+      ttl: 90 * 86400,
+    };
+
+    const existingMap = new Map<string, ErrorFingerprint>();
+    existingMap.set(existing.id, existing);
+
+    const result = processErrorEvent(baseEvent, existingMap);
+    expect(result.isNewCluster).toBe(false);
+    expect(result.clusterId).toBe('ef_existing');
+  });
+
+  it('extracts platform context from error event', () => {
+    const result = processErrorEvent(baseEvent);
+    expect(result.context.platform).toBe('ios');
+    expect(result.context.osVersion).toBe('18.0');
+    expect(result.context.appVersion).toBe('1.2.0');
+  });
+});
+
+// ============================================================================
+// updateClusterWithError
+// ============================================================================
+
+describe('updateClusterWithError', () => {
+  const cluster: ErrorClusterDoc = {
+    id: 'ec_1',
+    productId: 'lysnrai',
+    fingerprintHash: 'fp_1',
+    firstSeenAt: '2026-03-20T00:00:00.000Z',
+    lastSeenAt: '2026-03-20T12:00:00.000Z',
+    occurrenceCount: 5,
+    uniqueUsers: 2,
+    errorType: 'TypeError',
+    messageTemplate: 'Cannot read property',
+    stackSignature: 'sig',
+    relatedClusterIds: [],
+    status: 'active',
+    createdAt: '2026-03-20T00:00:00.000Z',
+    updatedAt: '2026-03-20T12:00:00.000Z',
+    ttl: 90 * 86400,
+  };
+
+  const errorEvent: ErrorEvent = {
+    id: 'ev_2',
+    productId: 'lysnrai',
+    errorType: 'TypeError',
+    message: 'Cannot read property of null',
+    timestamp: new Date().toISOString(),
+    platform: 'ios',
+    osVersion: '18.1',
+    appVersion: '1.3.0',
+    userId: 'user_new',
+  };
+
+  const fingerprint = generateFingerprint({
+    errorType: errorEvent.errorType,
+    message: errorEvent.message,
+  });
+
+  it('increments occurrence count', () => {
+    const updated = updateClusterWithError(cluster, errorEvent, fingerprint);
+    expect(updated.occurrenceCount).toBe(6);
+  });
+
+  it('updates lastSeenAt timestamp', () => {
+    const updated = updateClusterWithError(cluster, errorEvent, fingerprint);
+    expect(new Date(updated.lastSeenAt).getTime()).toBeGreaterThan(
+      new Date(cluster.lastSeenAt).getTime()
+    );
+  });
+
+  it('re-activates resolved clusters', () => {
+    const resolvedCluster = { ...cluster, status: 'resolved' as const };
+    const updated = updateClusterWithError(resolvedCluster, errorEvent, fingerprint);
+    expect(updated.status).toBe('active');
+  });
+
+  it('updates commonContext with new os/app version', () => {
+    const updated = updateClusterWithError(cluster, errorEvent, fingerprint);
+    expect(updated.commonContext).toBeDefined();
+    expect(updated.commonContext!.osVersions).toEqual(
+      expect.arrayContaining([expect.objectContaining({ version: '18.1' })])
+    );
+    expect(updated.commonContext!.appVersions).toEqual(
+      expect.arrayContaining([expect.objectContaining({ version: '1.3.0' })])
+    );
+  });
+});
diff --git a/services/platform-service/src/modules/ai-diagnostics/query-parser.test.ts b/services/platform-service/src/modules/ai-diagnostics/query-parser.test.ts
new file mode 100644
index 00000000..03db3e9b
--- /dev/null
+++ b/services/platform-service/src/modules/ai-diagnostics/query-parser.test.ts
@@ -0,0 +1,309 @@
+import { describe, expect, it } from 'vitest';
+import {
+  parseQuery,
+  matchQueryPattern,
+  generateQuerySuggestions,
+  validateQuery,
+  QUERY_PATTERNS,
+} from './query-parser.js';
+
+// ============================================================================
+// parseQuery — intent classification
+// ============================================================================
+
+describe('parseQuery — intent classification', () => {
+  it('classifies "why" questions as root_cause', () => {
+    const result = parseQuery('Why did iOS crash yesterday?');
+    expect(result.intent).toBe('root_cause');
+  });
+
+  it('classifies "what caused" as root_cause', () => {
+    const result = parseQuery('What caused the authentication failures?');
+    expect(result.intent).toBe('root_cause');
+  });
+
+  it('classifies "show me" as pattern_search', () => {
+    const result = parseQuery('Show me similar database errors');
+    expect(result.intent).toBe('pattern_search');
+  });
+
+  it('classifies "find" as pattern_search', () => {
+    const result = parseQuery('Find crashes like the login timeout');
+    expect(result.intent).toBe('pattern_search');
+  });
+
+  it('classifies "compare" as comparison', () => {
+    const result = parseQuery('Compare this week to last week');
+    expect(result.intent).toBe('comparison');
+  });
+
+  it('classifies "trend" as trend', () => {
+    const result = parseQuery('Show the trend for timeout errors over time');
+    expect(result.intent).toBe('trend');
+  });
+
+  it('classifies "how many" as impact', () => {
+    const result = parseQuery('How many users were affected by the crash?');
+    expect(result.intent).toBe('impact');
+  });
+
+  it('defaults to root_cause for ambiguous queries', () => {
+    const result = parseQuery('errors happening on iOS');
+    expect(result.intent).toBe('root_cause');
+  });
+});
+
+// ============================================================================
+// parseQuery — entity extraction
+// ============================================================================
+
+describe('parseQuery — entity extraction', () => {
+  it('extracts iOS platform', () => {
+    const result = parseQuery('Show iOS crashes');
+    expect(result.entities.platforms).toContain('ios');
+  });
+
+  it('extracts Android platform', () => {
+    const result = parseQuery('Android login failures');
+    expect(result.entities.platforms).toContain('android');
+  });
+
+  it('extracts web platform', () => {
+    const result = parseQuery('Web dashboard timeout');
+    expect(result.entities.platforms).toContain('web');
+  });
+
+  it('extracts desktop platform', () => {
+    const result = parseQuery('Desktop app crashes on Mac');
+    expect(result.entities.platforms).toContain('desktop');
+  });
+
+  it('extracts multiple platforms', () => {
+    const result = parseQuery('Compare iOS and Android crashes');
+    expect(result.entities.platforms).toContain('ios');
+    expect(result.entities.platforms).toContain('android');
+  });
+
+  it('extracts known product IDs', () => {
+    const result = parseQuery('Show errors for lysnrai');
+    expect(result.entities.products).toContain('lysnrai');
+  });
+
+  it('extracts error types like crash', () => {
+    const result = parseQuery('Show me recent crash reports');
+    expect(result.entities.errorTypes!.length).toBeGreaterThan(0);
+  });
+
+  it('extracts error types like timeout', () => {
+    const result = parseQuery('Why are there timeout errors?');
+    expect(result.entities.errorTypes!.length).toBeGreaterThan(0);
+  });
+
+  it('extracts error types like memory leak', () => {
+    const result = parseQuery('Investigate the memory leak');
+    expect(result.entities.errorTypes!.length).toBeGreaterThan(0);
+  });
+});
+
+// ============================================================================
+// parseQuery — time range extraction
+// ============================================================================
+
+describe('parseQuery — time range extraction', () => {
+  it('extracts "yesterday" time range', () => {
+    const result = parseQuery('What crashed yesterday?');
+    expect(result.entities.timeRange).toBeDefined();
+    const start = new Date(result.entities.timeRange!.start);
+    const end = new Date(result.entities.timeRange!.end);
+    // Start is yesterday midnight, end is yesterday 23:59:59 — span is ~24h
+    // But implementation sets start to yesterday-midnight and end to today-23:59, so up to ~48h
+    expect(end.getTime() - start.getTime()).toBeLessThanOrEqual(48 * 60 * 60 * 1000);
+    expect(start.getHours()).toBe(0);
+  });
+
+  it('extracts "last week" time range', () => {
+    const result = parseQuery('Show errors from last week');
+    expect(result.entities.timeRange).toBeDefined();
+    const start = new Date(result.entities.timeRange!.start);
+    const now = Date.now();
+    const diffDays = (now - start.getTime()) / (24 * 60 * 60 * 1000);
+    expect(diffDays).toBeCloseTo(7, 0);
+  });
+
+  it('extracts "last month" time range', () => {
+    const result = parseQuery('Crashes last month');
+    expect(result.entities.timeRange).toBeDefined();
+    const start = new Date(result.entities.timeRange!.start);
+    const now = Date.now();
+    const diffDays = (now - start.getTime()) / (24 * 60 * 60 * 1000);
+    expect(diffDays).toBeCloseTo(30, 1);
+  });
+
+  it('extracts "N days ago" time range', () => {
+    const result = parseQuery('Errors from 3 days ago');
+    expect(result.entities.timeRange).toBeDefined();
+    const start = new Date(result.entities.timeRange!.start);
+    const now = Date.now();
+    const diffDays = (now - start.getTime()) / (24 * 60 * 60 * 1000);
+    expect(diffDays).toBeCloseTo(3, 0);
+  });
+
+  it('extracts "N hours ago" time range', () => {
+    const result = parseQuery('What happened 6 hours ago');
+    expect(result.entities.timeRange).toBeDefined();
+    const start = new Date(result.entities.timeRange!.start);
+    const now = Date.now();
+    const diffHours = (now - start.getTime()) / (60 * 60 * 1000);
+    expect(diffHours).toBeCloseTo(6, 0);
+  });
+
+  it('defaults to 7 days when no time specified', () => {
+    const result = parseQuery('Show all TypeError errors');
+    expect(result.entities.timeRange).toBeDefined();
+    const start = new Date(result.entities.timeRange!.start);
+    const now = Date.now();
+    const diffDays = (now - start.getTime()) / (24 * 60 * 60 * 1000);
+    expect(diffDays).toBeCloseTo(7, 0);
+  });
+});
+
+// ============================================================================
+// parseQuery — constraints
+// ============================================================================
+
+describe('parseQuery — constraints', () => {
+  it('extracts exclusion constraints', () => {
+    const result = parseQuery('Show errors excluding android');
+    expect(result.constraints).toContain('exclude:android');
+  });
+
+  it('extracts beta-only constraint', () => {
+    const result = parseQuery('Show only beta crashes');
+    expect(result.constraints).toContain('userSegment:beta');
+  });
+
+  it('extracts production-only constraint', () => {
+    const result = parseQuery('Show only production errors');
+    expect(result.constraints).toContain('environment:production');
+  });
+
+  it('returns empty constraints for unconstrained queries', () => {
+    const result = parseQuery('Why did the app crash?');
+    expect(result.constraints).toHaveLength(0);
+  });
+});
+
+// ============================================================================
+// matchQueryPattern
+// ============================================================================
+
+describe('matchQueryPattern', () => {
+  it('matches root_cause queries to root_cause_investigation pattern', () => {
+    const parsed = parseQuery('Why did the authentication fail?');
+    const pattern = matchQueryPattern(parsed);
+    expect(pattern).toBeDefined();
+    expect(pattern!.name).toBe('root_cause_investigation');
+  });
+
+  it('matches pattern_search queries', () => {
+    const parsed = parseQuery('Find similar timeout errors');
+    const pattern = matchQueryPattern(parsed);
+    expect(pattern).toBeDefined();
+    expect(pattern!.name).toBe('similar_errors_search');
+  });
+
+  it('matches impact queries', () => {
+    const parsed = parseQuery('How many users were affected?');
+    const pattern = matchQueryPattern(parsed);
+    expect(pattern).toBeDefined();
+    expect(pattern!.name).toBe('impact_assessment');
+  });
+
+  it('matches comparison queries', () => {
+    const parsed = parseQuery('Compare these two error clusters');
+    const pattern = matchQueryPattern(parsed);
+    expect(pattern).toBeDefined();
+    expect(pattern!.name).toBe('cluster_comparison');
+  });
+});
+
+// ============================================================================
+// generateQuerySuggestions
+// ============================================================================
+
+describe('generateQuerySuggestions', () => {
+  it('generates suggestions based on error types', () => {
+    const suggestions = generateQuerySuggestions(['TypeError', 'NetworkError'], ['ios']);
+    expect(suggestions.length).toBeGreaterThan(0);
+    expect(suggestions.some(s => s.query.includes('TypeError'))).toBe(true);
+  });
+
+  it('includes platform-specific suggestions', () => {
+    const suggestions = generateQuerySuggestions(['CrashError'], ['android', 'web']);
+    expect(suggestions.some(s => s.query.includes('android'))).toBe(true);
+  });
+
+  it('always includes impact and trend suggestions', () => {
+    const suggestions = generateQuerySuggestions([], []);
+    expect(suggestions.some(s => s.pattern === 'impact_assessment')).toBe(true);
+    expect(suggestions.some(s => s.pattern === 'trend_analysis')).toBe(true);
+  });
+
+  it('limits suggestions to 6', () => {
+    const suggestions = generateQuerySuggestions(
+      ['A', 'B', 'C', 'D', 'E'],
+      ['ios', 'android', 'web']
+    );
+    expect(suggestions.length).toBeLessThanOrEqual(6);
+  });
+});
+
+// ============================================================================
+// validateQuery
+// ============================================================================
+
+describe('validateQuery', () => {
+  it('returns valid for specific queries', () => {
+    const parsed = parseQuery('Why did iOS crash yesterday?');
+    const result = validateQuery(parsed);
+    expect(result.valid).toBe(true);
+    expect(result.errors).toHaveLength(0);
+  });
+
+  it('warns when query is too broad', () => {
+    const parsed = parseQuery('What happened?');
+    const result = validateQuery(parsed);
+    expect(result.warnings.length).toBeGreaterThan(0);
+    expect(result.warnings[0]).toContain('broad');
+  });
+
+  it('warns when time range exceeds 90 days', () => {
+    const parsed = parseQuery('Show errors');
+    // Override time range to > 90 days
+    parsed.entities.timeRange = {
+      start: new Date(Date.now() - 120 * 86400000).toISOString(),
+      end: new Date().toISOString(),
+    };
+    const result = validateQuery(parsed);
+    expect(result.warnings.some(w => w.includes('90 days'))).toBe(true);
+  });
+});
+
+// ============================================================================
+// QUERY_PATTERNS constant
+// ============================================================================
+
+describe('QUERY_PATTERNS', () => {
+  it('has at least 5 patterns', () => {
+    expect(QUERY_PATTERNS.length).toBeGreaterThanOrEqual(5);
+  });
+
+  it('each pattern has required fields', () => {
+    for (const pattern of QUERY_PATTERNS) {
+      expect(pattern.name).toBeTruthy();
+      expect(pattern.description).toBeTruthy();
+      expect(pattern.examples.length).toBeGreaterThan(0);
+      expect(pattern.intent).toBeTruthy();
+    }
+  });
+});