diff --git a/services/platform-service/src/lib/cosmos-init.ts b/services/platform-service/src/lib/cosmos-init.ts
index eecbab2e..bd53980f 100644
--- a/services/platform-service/src/lib/cosmos-init.ts
+++ b/services/platform-service/src/lib/cosmos-init.ts
@@ -34,6 +34,10 @@ const CONTAINER_DEFS: Record<string, ContainerConfig> = {
   daily_briefs: { partitionKeyPath: '/userId' },
   reflections: { partitionKeyPath: '/userId' },
   brain_insights: { partitionKeyPath: '/userId' },
+  // Telemetry (client diagnostics — see docs/WINDSURF/CLIENT_TELEMETRY_DESIGN.md)
+  telemetry_events: { partitionKeyPath: '/pk', defaultTtl: 30 * 86400 },
+  telemetry_error_clusters: { partitionKeyPath: '/pk', defaultTtl: 90 * 86400 },
+  telemetry_collection_policies: { partitionKeyPath: '/productId' },
 };
 
 export async function initCosmosIfNeeded(): Promise<void> {
diff --git a/services/platform-service/src/modules/telemetry/repository.ts b/services/platform-service/src/modules/telemetry/repository.ts
new file mode 100644
index 00000000..65975bb4
--- /dev/null
+++ b/services/platform-service/src/modules/telemetry/repository.ts
@@ -0,0 +1,254 @@
+/**
+ * Telemetry repository — Cosmos DB CRUD for events, policies, and clusters.
+ */
+
+import { getContainer } from '../../lib/cosmos.js';
+import type {
+  TelemetryEventDoc,
+  TelemetryCollectionPolicyDoc,
+  TelemetryErrorCluster,
+  TelemetryQueryInput,
+} from './types.js';
+
+// ─── Container accessors ────────────────────────────────────────────
+
+function eventsContainer() {
+  return getContainer('telemetry_events');
+}
+
+function policiesContainer() {
+  return getContainer('telemetry_collection_policies');
+}
+
+function clustersContainer() {
+  return getContainer('telemetry_error_clusters');
+}
+
+// ─── Events ─────────────────────────────────────────────────────────
+
+export async function upsertEvent(doc: TelemetryEventDoc): Promise<void> {
+  await eventsContainer().items.upsert(doc);
+}
+
+export async function upsertEventsBatch(docs: TelemetryEventDoc[]): Promise<void> {
+  // Cosmos DB doesn't have native batch across partitions.
+  // We upsert individually; for v1 this is acceptable.
+  // TODO: Group by pk and use bulk operations for same-partition batches.
+  const promises = docs.map(doc => eventsContainer().items.upsert(doc));
+  await Promise.all(promises);
+}
+
+export async function queryEvents(
+  productId: string,
+  input: TelemetryQueryInput
+): Promise<{ events: TelemetryEventDoc[]; continuationToken?: string }> {
+  const conditions: string[] = ['c.productId = @productId'];
+  const parameters: Array<{ name: string; value: string | number | boolean }> = [
+    { name: '@productId', value: productId },
+  ];
+
+  if (input.userId) {
+    conditions.push('c.userId = @userId');
+    parameters.push({ name: '@userId', value: input.userId });
+  }
+  if (input.anonymousInstallId) {
+    conditions.push('c.anonymousInstallId = @anonymousInstallId');
+    parameters.push({ name: '@anonymousInstallId', value: input.anonymousInstallId });
+  }
+  if (input.platform) {
+    conditions.push('c.platform = @platform');
+    parameters.push({ name: '@platform', value: input.platform });
+  }
+  if (input.channel) {
+    conditions.push('c.channel = @channel');
+    parameters.push({ name: '@channel', value: input.channel });
+  }
+  if (input.osFamily) {
+    conditions.push('c.osFamily = @osFamily');
+    parameters.push({ name: '@osFamily', value: input.osFamily });
+  }
+  if (input.appVersion) {
+    conditions.push('c.appVersion = @appVersion');
+    parameters.push({ name: '@appVersion', value: input.appVersion });
+  }
+  if (input.buildNumber) {
+    conditions.push('c.buildNumber = @buildNumber');
+    parameters.push({ name: '@buildNumber', value: input.buildNumber });
+  }
+  if (input.module) {
+    conditions.push('c.module = @module');
+    parameters.push({ name: '@module', value: input.module });
+  }
+  if (input.eventName) {
+    conditions.push('c.eventName = @eventName');
+    parameters.push({ name: '@eventName', value: input.eventName });
+  }
+  if (input.eventType) {
+    conditions.push('c.eventType = @eventType');
+    parameters.push({ name: '@eventType', value: input.eventType });
+  }
+  if (input.from) {
+    conditions.push('c.occurredAt >= @from');
+    parameters.push({ name: '@from', value: input.from });
+  }
+  if (input.to) {
+    conditions.push('c.occurredAt <= @to');
+    parameters.push({ name: '@to', value: input.to });
+  }
+
+  const query = `SELECT * FROM c WHERE ${conditions.join(' AND ')} ORDER BY c.occurredAt DESC`;
+
+  const iterator = eventsContainer().items.query<TelemetryEventDoc>(
+    { query, parameters },
+    {
+      maxItemCount: input.limit,
+      continuationToken: input.continuationToken || undefined,
+    }
+  );
+
+  const { resources, continuationToken } = await iterator.fetchNext();
+  return {
+    events: resources,
+    continuationToken: continuationToken || undefined,
+  };
+}
+
+export async function deleteEventsByUserId(productId: string, userId: string): Promise<number> {
+  // Find all events for this user, then delete them
+  const { resources } = await eventsContainer()
+    .items.query<{ id: string; pk: string }>({
+      query: 'SELECT c.id, c.pk FROM c WHERE c.productId = @productId AND c.userId = @userId',
+      parameters: [
+        { name: '@productId', value: productId },
+        { name: '@userId', value: userId },
+      ],
+    })
+    .fetchAll();
+
+  let deleted = 0;
+  for (const doc of resources) {
+    try {
+      await eventsContainer().item(doc.id, doc.pk).delete();
+      deleted++;
+    } catch {
+      // Skip docs that fail to delete (already deleted, etc.)
+    }
+  }
+  return deleted;
+}
+
+// ─── Policies ───────────────────────────────────────────────────────
+
+export async function listPolicies(productId: string): Promise<TelemetryCollectionPolicyDoc[]> {
+  const { resources } = await policiesContainer()
+    .items.query<TelemetryCollectionPolicyDoc>({
+      query: 'SELECT * FROM c WHERE c.productId = @productId ORDER BY c.priority DESC',
+      parameters: [{ name: '@productId', value: productId }],
+    })
+    .fetchAll();
+  return resources;
+}
+
+export async function getPolicy(
+  id: string,
+  productId: string
+): Promise<TelemetryCollectionPolicyDoc | null> {
+  try {
+    const { resource } = await policiesContainer()
+      .item(id, productId)
+      .read<TelemetryCollectionPolicyDoc>();
+    return resource ?? null;
+  } catch {
+    return null;
+  }
+}
+
+export async function createPolicy(
+  doc: TelemetryCollectionPolicyDoc
+): Promise<TelemetryCollectionPolicyDoc> {
+  const { resource } = await policiesContainer().items.create(doc);
+  return resource as TelemetryCollectionPolicyDoc;
+}
+
+export async function updatePolicy(
+  id: string,
+  productId: string,
+  updates: Partial<TelemetryCollectionPolicyDoc>
+): Promise<TelemetryCollectionPolicyDoc | null> {
+  try {
+    const { resource: existing } = await policiesContainer()
+      .item(id, productId)
+      .read<TelemetryCollectionPolicyDoc>();
+    if (!existing) return null;
+    const merged = { ...existing, ...updates, updatedAt: new Date().toISOString() };
+    const { resource } = await policiesContainer().item(id, productId).replace(merged);
+    return resource as TelemetryCollectionPolicyDoc;
+  } catch {
+    return null;
+  }
+}
+
+export async function deletePolicy(id: string, productId: string): Promise<boolean> {
+  try {
+    await policiesContainer().item(id, productId).delete();
+    return true;
+  } catch {
+    return false;
+  }
+}
+
+// ─── Clusters ───────────────────────────────────────────────────────
+
+export async function listClusters(
+  productId: string,
+  filters?: {
+    platform?: string;
+    module?: string;
+    from?: string;
+    to?: string;
+    limit?: number;
+  }
+): Promise<TelemetryErrorCluster[]> {
+  const conditions: string[] = ['c.productId = @productId'];
+  const parameters: Array<{ name: string; value: string | number | boolean }> = [
+    { name: '@productId', value: productId },
+  ];
+
+  if (filters?.platform) {
+    conditions.push('c.platform = @platform');
+    parameters.push({ name: '@platform', value: filters.platform });
+  }
+  if (filters?.module) {
+    conditions.push('c.module = @module');
+    parameters.push({ name: '@module', value: filters.module });
+  }
+  if (filters?.from) {
+    conditions.push('c.lastSeenAt >= @from');
+    parameters.push({ name: '@from', value: filters.from });
+  }
+  if (filters?.to) {
+    conditions.push('c.lastSeenAt <= @to');
+    parameters.push({ name: '@to', value: filters.to });
+  }
+
+  const limit = filters?.limit ?? 50;
+  const query = `SELECT TOP ${limit} * FROM c WHERE ${conditions.join(' AND ')} ORDER BY c.totalCount DESC`;
+
+  const { resources } = await clustersContainer()
+    .items.query<TelemetryErrorCluster>({ query, parameters })
+    .fetchAll();
+  return resources;
+}
+
+export async function upsertCluster(cluster: TelemetryErrorCluster): Promise<void> {
+  await clustersContainer().items.upsert(cluster);
+}
+
+export async function getCluster(id: string, pk: string): Promise<TelemetryErrorCluster | null> {
+  try {
+    const { resource } = await clustersContainer().item(id, pk).read<TelemetryErrorCluster>();
+    return resource ?? null;
+  } catch {
+    return null;
+  }
+}
diff --git a/services/platform-service/src/modules/telemetry/routes.ts b/services/platform-service/src/modules/telemetry/routes.ts
new file mode 100644
index 00000000..233d0bf9
--- /dev/null
+++ b/services/platform-service/src/modules/telemetry/routes.ts
@@ -0,0 +1,535 @@
+/**
+ * Telemetry REST endpoints.
+ *
+ * POST   /telemetry/events       — batch ingest (any auth)
+ * GET    /telemetry/config       — collection config for clients
+ * GET    /telemetry/query        — admin query
+ * GET    /telemetry/clusters     — admin error clusters
+ * GET    /telemetry/policies     — list policies (admin)
+ * POST   /telemetry/policies     — create policy (admin)
+ * PUT    /telemetry/policies/:id — update policy (admin)
+ * DELETE /telemetry/policies/:id — delete policy (admin)
+ * DELETE /telemetry/user/:userId — GDPR erasure (admin)
+ */
+
+import type { FastifyInstance } from 'fastify';
+import { randomUUID } from 'node:crypto';
+import { createHash } from 'node:crypto';
+import { getRequestProductId } from '../../lib/request-context.js';
+import { BadRequestError, NotFoundError, UnauthorizedError } from '../../lib/errors.js';
+import { hashUserFlag } from '../flags/routes.js';
+import * as repo from './repository.js';
+import {
+  TelemetryIngestRequestSchema,
+  CreatePolicySchema,
+  UpdatePolicySchema,
+  TelemetryQuerySchema,
+  type TelemetryEventDoc,
+  type TelemetryCollectionPolicyDoc,
+  type TelemetryCollectionConfig,
+  type TelemetryErrorCluster,
+} from './types.js';
+
+// ─── Helpers ────────────────────────────────────────────────────────
+
+const DEFAULT_EVENT_TTL_DAYS = parseInt(process.env.TELEMETRY_EVENT_TTL_DAYS ?? '30', 10);
+const DEFAULT_CLUSTER_TTL_DAYS = parseInt(process.env.TELEMETRY_CLUSTER_TTL_DAYS ?? '90', 10);
+const TELEMETRY_ENABLED = process.env.TELEMETRY_ENABLED !== 'false';
+const PII_SCAN_ENABLED = process.env.TELEMETRY_PII_SCAN_ENABLED !== 'false';
+const CLIENT_BATCH_SIZE = parseInt(process.env.TELEMETRY_CLIENT_BATCH_SIZE ?? '20', 10);
+const CLIENT_FLUSH_MS = parseInt(process.env.TELEMETRY_CLIENT_FLUSH_MS ?? '60000', 10);
+const CLIENT_MAX_QUEUE = parseInt(process.env.TELEMETRY_CLIENT_MAX_QUEUE ?? '200', 10);
+
+/** PII patterns — reject events containing these. */
+const PII_PATTERNS = [
+  /\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Z]{2,}\b/i, // email
+  /\b\d{3}[-.]?\d{3}[-.]?\d{4}\b/, // US phone
+  /\b\d{4}[- ]?\d{4}[- ]?\d{4}[- ]?\d{4}\b/, // credit card
+  /\b\d{3}-\d{2}-\d{4}\b/, // SSN
+];
+
+function containsPII(text: string): boolean {
+  if (!PII_SCAN_ENABLED) return false;
+  return PII_PATTERNS.some(p => p.test(text));
+}
+
+function computePk(productId: string, occurredAt: string, platform: string): string {
+  const date = new Date(occurredAt);
+  const yyyyMM = `${date.getUTCFullYear()}${String(date.getUTCMonth() + 1).padStart(2, '0')}`;
+  return `${productId}:${yyyyMM}:${platform}`;
+}
+
+function normalizeMessage(msg: string): string {
+  return msg
+    .replace(/[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}/gi, '<UUID>')
+    .replace(/\d+/g, '<N>')
+    .replace(/\/[\w/.]+/g, '<PATH>')
+    .toLowerCase()
+    .trim();
+}
+
+function generateFingerprint(event: TelemetryEventDoc): string {
+  const input = [
+    event.platform,
+    event.channel,
+    event.module,
+    event.eventName,
+    event.errorDomain ?? '',
+    event.errorCode ?? '',
+    normalizeMessage(event.message ?? ''),
+  ].join(':');
+  return createHash('sha256').update(input).digest('hex').substring(0, 16);
+}
+
+function requireAdmin(req: { jwtPayload?: { role?: string } }): void {
+  if (req.jwtPayload?.role !== 'admin') {
+    throw new UnauthorizedError('Admin access required');
+  }
+}
+
+// ─── Policy evaluation helpers ──────────────────────────────────────
+
+interface ClientContext {
+  userId?: string;
+  anonymousInstallId?: string;
+  platform?: string;
+  channel?: string;
+  osFamily?: string;
+  appVersion?: string;
+  buildNumber?: string;
+  releaseChannel?: string;
+  countryCode?: string;
+  regionCode?: string;
+}
+
+function policyMatchesContext(policy: TelemetryCollectionPolicyDoc, ctx: ClientContext): boolean {
+  const t = policy.targeting;
+
+  // Check time bounds
+  const now = new Date().toISOString();
+  if (policy.startsAt && now < policy.startsAt) return false;
+  if (policy.expiresAt && now > policy.expiresAt) return false;
+
+  // User targeting
+  if (t.userIds?.length && ctx.userId && !t.userIds.includes(ctx.userId)) return false;
+  if (
+    t.anonymousInstallIds?.length &&
+    ctx.anonymousInstallId &&
+    !t.anonymousInstallIds.includes(ctx.anonymousInstallId)
+  )
+    return false;
+
+  // Platform targeting
+  if (t.platforms?.length && ctx.platform && !t.platforms.includes(ctx.platform as never))
+    return false;
+  if (t.channels?.length && ctx.channel && !t.channels.includes(ctx.channel as never)) return false;
+  if (t.osFamilies?.length && ctx.osFamily && !t.osFamilies.includes(ctx.osFamily as never))
+    return false;
+
+  // Version targeting
+  if (t.appVersions?.length && ctx.appVersion && !t.appVersions.includes(ctx.appVersion))
+    return false;
+  if (t.buildNumbers?.length && ctx.buildNumber && !t.buildNumbers.includes(ctx.buildNumber))
+    return false;
+  if (t.buildNumberRange && ctx.buildNumber) {
+    const bn = parseInt(ctx.buildNumber, 10);
+    if (!isNaN(bn)) {
+      if (t.buildNumberRange.min !== undefined && bn < t.buildNumberRange.min) return false;
+      if (t.buildNumberRange.max !== undefined && bn > t.buildNumberRange.max) return false;
+    }
+  }
+
+  // Region targeting
+  if (t.countryCodes?.length && ctx.countryCode && !t.countryCodes.includes(ctx.countryCode))
+    return false;
+  if (t.regionCodes?.length && ctx.regionCode && !t.regionCodes.includes(ctx.regionCode))
+    return false;
+
+  // Release channel targeting
+  if (
+    t.releaseChannels?.length &&
+    ctx.releaseChannel &&
+    !t.releaseChannels.includes(ctx.releaseChannel as never)
+  )
+    return false;
+
+  // Percentage rollout (deterministic)
+  if (t.percentage !== undefined && t.percentage < 100) {
+    const identity = ctx.userId || ctx.anonymousInstallId || '';
+    if (!identity) return false;
+    const bucket = hashUserFlag(identity, `telemetry_policy_${policy.id}`);
+    if (bucket >= t.percentage) return false;
+  }
+
+  return true;
+}
+
+function mergePolicies(policies: TelemetryCollectionPolicyDoc[]): TelemetryCollectionConfig {
+  if (policies.length === 0) {
+    // Hardcoded default
+    return {
+      enabled: TELEMETRY_ENABLED,
+      eventTypes: ['warn', 'error', 'fatal'],
+      modules: [],
+      samplingRates: { debug: 0, info: 0, warn: 0.5, error: 1, fatal: 1 },
+      batchSize: CLIENT_BATCH_SIZE,
+      flushIntervalMs: CLIENT_FLUSH_MS,
+      maxQueueSize: CLIENT_MAX_QUEUE,
+    };
+  }
+
+  // Policies are already sorted by priority DESC
+  const eventTypesSet = new Set<string>();
+  const modulesSet = new Set<string>();
+  const rates: Record<string, number> = { debug: 0, info: 0, warn: 0, error: 0, fatal: 0 };
+  let enabled = TELEMETRY_ENABLED;
+
+  for (const p of policies) {
+    // Union event types
+    for (const et of p.eventTypes) {
+      eventTypesSet.add(et);
+      // Highest-priority policy's rate wins per event type
+      if (rates[et] === 0) {
+        rates[et] = p.samplingRate;
+      }
+    }
+    // Union modules
+    for (const m of p.modules) {
+      modulesSet.add(m);
+    }
+    // samplingRate 0 from highest-priority policy disables everything
+    if (p.priority >= 999 && p.samplingRate === 0) {
+      enabled = false;
+    }
+  }
+
+  return {
+    enabled,
+    eventTypes: Array.from(eventTypesSet),
+    modules: Array.from(modulesSet),
+    samplingRates: {
+      debug: rates.debug,
+      info: rates.info,
+      warn: rates.warn,
+      error: rates.error,
+      fatal: rates.fatal,
+    },
+    batchSize: CLIENT_BATCH_SIZE,
+    flushIntervalMs: CLIENT_FLUSH_MS,
+    maxQueueSize: CLIENT_MAX_QUEUE,
+  };
+}
+
+// ─── Cluster update ─────────────────────────────────────────────────
+
+async function updateClusterForEvent(event: TelemetryEventDoc): Promise<void> {
+  if (!['warn', 'error', 'fatal'].includes(event.eventType)) return;
+
+  const fingerprint = event.fingerprint || generateFingerprint(event);
+  const date = new Date(event.occurredAt);
+  const yyyyMM = `${date.getUTCFullYear()}${String(date.getUTCMonth() + 1).padStart(2, '0')}`;
+  const clusterId = `${fingerprint}:${yyyyMM}`;
+  const pk = `${event.productId}:${event.platform}:${event.module}`;
+
+  const existing = await repo.getCluster(clusterId, pk);
+
+  if (existing) {
+    existing.totalCount++;
+    existing.lastSeenAt = event.receivedAt;
+    existing.sampleMessage = event.message;
+    existing.sampleErrorDomain = event.errorDomain;
+    existing.sampleErrorCode = event.errorCode;
+
+    // Update affected users (dedup, cap 100)
+    const uid = event.userId || event.anonymousInstallId;
+    if (uid && event.userId && !existing.affectedUserIds.includes(uid)) {
+      if (existing.affectedUserIds.length < 100) existing.affectedUserIds.push(uid);
+    }
+    if (uid && event.anonymousInstallId && !existing.affectedInstallIds.includes(uid)) {
+      if (existing.affectedInstallIds.length < 100) existing.affectedInstallIds.push(uid);
+    }
+    if (!existing.affectedOsFamilies.includes(event.osFamily)) {
+      existing.affectedOsFamilies.push(event.osFamily);
+    }
+
+    // Update version breakdown
+    const vEntry = existing.affectedVersions.find(
+      v => v.appVersion === event.appVersion && v.buildNumber === event.buildNumber
+    );
+    if (vEntry) {
+      vEntry.count++;
+      vEntry.lastSeenAt = event.receivedAt;
+    } else if (existing.affectedVersions.length < 50) {
+      existing.affectedVersions.push({
+        appVersion: event.appVersion,
+        buildNumber: event.buildNumber,
+        count: 1,
+        lastSeenAt: event.receivedAt,
+      });
+    }
+
+    // Escalate severity
+    const severityOrder = { warn: 0, error: 1, fatal: 2 };
+    const eventSev = event.eventType as 'warn' | 'error' | 'fatal';
+    if ((severityOrder[eventSev] ?? 0) > (severityOrder[existing.severity] ?? 0)) {
+      existing.severity = eventSev;
+    }
+
+    await repo.upsertCluster(existing);
+  } else {
+    const newCluster: TelemetryErrorCluster = {
+      id: clusterId,
+      pk,
+      productId: event.productId,
+      fingerprint,
+      platform: event.platform,
+      channel: event.channel,
+      module: event.module,
+      eventName: event.eventName,
+      affectedVersions: [
+        {
+          appVersion: event.appVersion,
+          buildNumber: event.buildNumber,
+          count: 1,
+          lastSeenAt: event.receivedAt,
+        },
+      ],
+      firstSeenAt: event.receivedAt,
+      lastSeenAt: event.receivedAt,
+      totalCount: 1,
+      affectedUserIds: event.userId ? [event.userId] : [],
+      affectedInstallIds: event.anonymousInstallId ? [event.anonymousInstallId] : [],
+      affectedOsFamilies: [event.osFamily],
+      sampleErrorDomain: event.errorDomain,
+      sampleErrorCode: event.errorCode,
+      sampleMessage: event.message,
+      severity: event.eventType as 'warn' | 'error' | 'fatal',
+      ttl: DEFAULT_CLUSTER_TTL_DAYS * 86400,
+    };
+    await repo.upsertCluster(newCluster);
+  }
+}
+
+// ─── Routes ─────────────────────────────────────────────────────────
+
+export async function telemetryRoutes(app: FastifyInstance) {
+  // ── Batch ingest ──────────────────────────────────────────────
+  app.post('/telemetry/events', async (req, reply) => {
+    if (!TELEMETRY_ENABLED) {
+      return { accepted: 0, rejected: 0, serverTime: new Date().toISOString() };
+    }
+
+    // Auth: JWT or X-Install-Token
+    const installToken = req.headers['x-install-token'] as string | undefined;
+    if (!req.jwtPayload && !installToken) {
+      throw new UnauthorizedError('JWT or X-Install-Token required');
+    }
+
+    const parsed = TelemetryIngestRequestSchema.safeParse(req.body);
+    if (!parsed.success) {
+      throw new BadRequestError(parsed.error.issues.map(i => i.message).join('; '));
+    }
+
+    const { productId, events } = parsed.data;
+    const now = new Date().toISOString();
+    const ttl = DEFAULT_EVENT_TTL_DAYS * 86400;
+
+    let accepted = 0;
+    let rejected = 0;
+    const errors: Array<{ index: number; reason: string }> = [];
+    const docsToInsert: TelemetryEventDoc[] = [];
+
+    for (let i = 0; i < events.length; i++) {
+      const event = events[i];
+
+      // Validate productId matches request-level
+      if (event.productId !== productId) {
+        errors.push({ index: i, reason: `productId mismatch: expected ${productId}` });
+        rejected++;
+        continue;
+      }
+
+      // PII scan
+      const fieldsToScan = [event.message, event.eventName, event.errorDomain].filter(Boolean);
+      if (fieldsToScan.some(f => containsPII(f!))) {
+        errors.push({ index: i, reason: 'PII detected' });
+        rejected++;
+        continue;
+      }
+
+      const pk = computePk(productId, event.occurredAt, event.platform);
+      const doc: TelemetryEventDoc = {
+        ...event,
+        pk,
+        receivedAt: now,
+        ttl,
+      };
+
+      docsToInsert.push(doc);
+      accepted++;
+    }
+
+    // Batch upsert (idempotent by event id)
+    if (docsToInsert.length > 0) {
+      await repo.upsertEventsBatch(docsToInsert);
+
+      // Fire-and-forget cluster updates for warn/error/fatal
+      for (const doc of docsToInsert) {
+        if (['warn', 'error', 'fatal'].includes(doc.eventType)) {
+          updateClusterForEvent(doc).catch(err => {
+            req.log.warn({ err, eventId: doc.id }, 'Cluster update failed');
+          });
+        }
+      }
+    }
+
+    reply.code(accepted > 0 ? 200 : 400);
+    return {
+      accepted,
+      rejected,
+      errors: errors.length > 0 ? errors : undefined,
+      serverTime: now,
+    };
+  });
+
+  // ── Collection config (client poll) ───────────────────────────
+  app.get('/telemetry/config', async req => {
+    if (!TELEMETRY_ENABLED) {
+      return {
+        enabled: false,
+        eventTypes: [],
+        modules: [],
+        samplingRates: { debug: 0, info: 0, warn: 0, error: 0, fatal: 0 },
+        batchSize: CLIENT_BATCH_SIZE,
+        flushIntervalMs: CLIENT_FLUSH_MS,
+        maxQueueSize: CLIENT_MAX_QUEUE,
+      } satisfies TelemetryCollectionConfig;
+    }
+
+    const productId = getRequestProductId(req);
+    const ctx: ClientContext = req.query as ClientContext;
+
+    const allPolicies = await repo.listPolicies(productId);
+    const activePolicies = allPolicies.filter(p => p.enabled && policyMatchesContext(p, ctx));
+
+    return mergePolicies(activePolicies);
+  });
+
+  // ── Admin: query events ───────────────────────────────────────
+  app.get('/telemetry/query', async req => {
+    requireAdmin(req);
+    const productId = getRequestProductId(req);
+    const parsed = TelemetryQuerySchema.safeParse(req.query);
+    if (!parsed.success) {
+      throw new BadRequestError(parsed.error.issues.map(i => i.message).join('; '));
+    }
+    const result = await repo.queryEvents(productId, parsed.data);
+    return {
+      events: result.events,
+      total: result.events.length,
+      continuationToken: result.continuationToken,
+    };
+  });
+
+  // ── Admin: error clusters ─────────────────────────────────────
+  app.get('/telemetry/clusters', async req => {
+    requireAdmin(req);
+    const productId = getRequestProductId(req);
+    const {
+      platform,
+      module: mod,
+      from,
+      to,
+      limit,
+    } = req.query as {
+      platform?: string;
+      module?: string;
+      from?: string;
+      to?: string;
+      limit?: string;
+    };
+    const clusters = await repo.listClusters(productId, {
+      platform,
+      module: mod,
+      from,
+      to,
+      limit: limit ? parseInt(limit, 10) : undefined,
+    });
+    return { clusters, total: clusters.length };
+  });
+
+  // ── Admin: list policies ──────────────────────────────────────
+  app.get('/telemetry/policies', async req => {
+    requireAdmin(req);
+    const productId = getRequestProductId(req);
+    return { policies: await repo.listPolicies(productId) };
+  });
+
+  // ── Admin: create policy ──────────────────────────────────────
+  app.post('/telemetry/policies', async (req, reply) => {
+    requireAdmin(req);
+    const productId = getRequestProductId(req);
+    const parsed = CreatePolicySchema.safeParse(req.body);
+    if (!parsed.success) {
+      throw new BadRequestError(parsed.error.issues.map(i => i.message).join('; '));
+    }
+
+    const now = new Date().toISOString();
+    const doc: TelemetryCollectionPolicyDoc = {
+      id: randomUUID(),
+      productId,
+      ...parsed.data,
+      createdAt: now,
+      updatedAt: now,
+      createdBy: req.jwtPayload?.sub ?? 'unknown',
+    };
+
+    const created = await repo.createPolicy(doc);
+    reply.code(201);
+    return created;
+  });
+
+  // ── Admin: update policy ──────────────────────────────────────
+  app.put('/telemetry/policies/:id', async req => {
+    requireAdmin(req);
+    const { id } = req.params as { id: string };
+    const productId = getRequestProductId(req);
+
+    const parsed = UpdatePolicySchema.safeParse(req.body);
+    if (!parsed.success) {
+      throw new BadRequestError(parsed.error.issues.map(i => i.message).join('; '));
+    }
+
+    // Convert null to undefined for optional fields (Zod nullable → TS optional)
+    const updates: Record<string, unknown> = { ...parsed.data };
+    if (updates.startsAt === null) updates.startsAt = undefined;
+    if (updates.expiresAt === null) updates.expiresAt = undefined;
+
+    const updated = await repo.updatePolicy(
+      id,
+      productId,
+      updates as Partial<TelemetryCollectionPolicyDoc>
+    );
+    if (!updated) throw new NotFoundError('Policy not found');
+    return updated;
+  });
+
+  // ── Admin: delete policy ──────────────────────────────────────
+  app.delete('/telemetry/policies/:id', async req => {
+    requireAdmin(req);
+    const { id } = req.params as { id: string };
+    const productId = getRequestProductId(req);
+    const deleted = await repo.deletePolicy(id, productId);
+    if (!deleted) throw new NotFoundError('Policy not found');
+    return { success: true };
+  });
+
+  // ── Admin: GDPR erasure ───────────────────────────────────────
+  app.delete('/telemetry/user/:userId', async req => {
+    requireAdmin(req);
+    const { userId } = req.params as { userId: string };
+    const productId = getRequestProductId(req);
+    const eventsDeleted = await repo.deleteEventsByUserId(productId, userId);
+    return { userId, eventsDeleted, clustersUpdated: 0 };
+  });
+}
diff --git a/services/platform-service/src/modules/telemetry/telemetry.test.ts b/services/platform-service/src/modules/telemetry/telemetry.test.ts
new file mode 100644
index 00000000..199bea96
--- /dev/null
+++ b/services/platform-service/src/modules/telemetry/telemetry.test.ts
@@ -0,0 +1,317 @@
+/**
+ * Telemetry module tests — types, policy evaluation, fingerprinting.
+ */
+
+import { describe, it, expect } from 'vitest';
+import {
+  TelemetryEventSchema,
+  TelemetryIngestRequestSchema,
+  CreatePolicySchema,
+  UpdatePolicySchema,
+  TelemetryQuerySchema,
+} from './types.js';
+
+// ─── Minimal valid event for reuse ──────────────────────────────────
+
+function validEvent(overrides: Record<string, unknown> = {}) {
+  return {
+    id: '550e8400-e29b-41d4-a716-446655440000',
+    productId: 'lysnrai',
+    anonymousInstallId: '660e8400-e29b-41d4-a716-446655440001',
+    sessionId: 'sess_abc123',
+    platform: 'ios',
+    channel: 'keyboard_extension',
+    osFamily: 'ios',
+    appVersion: '1.0.0',
+    buildNumber: '26',
+    releaseChannel: 'beta',
+    eventType: 'error',
+    module: 'keyboard_dictation',
+    eventName: 'recognition_failed',
+    occurredAt: '2026-02-17T08:00:00.000Z',
+    ...overrides,
+  };
+}
+
+// ─── TelemetryEventSchema ───────────────────────────────────────────
+
+describe('TelemetryEventSchema', () => {
+  it('accepts a valid event with anonymousInstallId', () => {
+    const result = TelemetryEventSchema.safeParse(validEvent());
+    expect(result.success).toBe(true);
+  });
+
+  it('accepts a valid event with userId', () => {
+    const result = TelemetryEventSchema.safeParse(
+      validEvent({ userId: 'usr_abc', anonymousInstallId: undefined })
+    );
+    expect(result.success).toBe(true);
+  });
+
+  it('accepts event with both userId and anonymousInstallId', () => {
+    const result = TelemetryEventSchema.safeParse(validEvent({ userId: 'usr_abc' }));
+    expect(result.success).toBe(true);
+  });
+
+  it('rejects event with neither userId nor anonymousInstallId', () => {
+    const result = TelemetryEventSchema.safeParse(validEvent({ anonymousInstallId: undefined }));
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects empty id', () => {
+    const result = TelemetryEventSchema.safeParse(validEvent({ id: 'not-a-uuid' }));
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects invalid platform', () => {
+    const result = TelemetryEventSchema.safeParse(validEvent({ platform: 'symbian' }));
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects invalid channel', () => {
+    const result = TelemetryEventSchema.safeParse(validEvent({ channel: 'fax_machine' }));
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects invalid osFamily', () => {
+    const result = TelemetryEventSchema.safeParse(validEvent({ osFamily: 'beos' }));
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects invalid eventType', () => {
+    const result = TelemetryEventSchema.safeParse(validEvent({ eventType: 'trace' }));
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects message > 512 chars', () => {
+    const result = TelemetryEventSchema.safeParse(validEvent({ message: 'x'.repeat(513) }));
+    expect(result.success).toBe(false);
+  });
+
+  it('accepts message at exactly 512 chars', () => {
+    const result = TelemetryEventSchema.safeParse(validEvent({ message: 'x'.repeat(512) }));
+    expect(result.success).toBe(true);
+  });
+
+  it('rejects stackTrace > 8192 chars', () => {
+    const result = TelemetryEventSchema.safeParse(
+      validEvent({ stackTrace: 'x'.repeat(8193), eventType: 'fatal' })
+    );
+    expect(result.success).toBe(false);
+  });
+
+  it('accepts optional fields', () => {
+    const result = TelemetryEventSchema.safeParse(
+      validEvent({
+        feature: 'voice_typing',
+        errorDomain: 'kAFAssistantErrorDomain',
+        errorCode: '209',
+        message: 'Recognition timed out',
+        fingerprint: 'abc123def456',
+        tags: { backend: 'azure' },
+        metrics: { duration_ms: 5000 },
+        context: { dictation: { backend: 'azure' } },
+        osVersion: 'iOS 18.2',
+        deviceModel: 'iPhone17,3',
+        locale: 'en-US',
+        timezone: 'America/Los_Angeles',
+      })
+    );
+    expect(result.success).toBe(true);
+  });
+
+  it('validates all platform enum values', () => {
+    for (const p of ['ios', 'android', 'web', 'desktop']) {
+      const result = TelemetryEventSchema.safeParse(validEvent({ platform: p }));
+      expect(result.success).toBe(true);
+    }
+  });
+
+  it('validates all channel enum values', () => {
+    for (const c of [
+      'mobile_app',
+      'keyboard_extension',
+      'web_app',
+      'desktop_app',
+      'backend_service',
+    ]) {
+      const result = TelemetryEventSchema.safeParse(validEvent({ channel: c }));
+      expect(result.success).toBe(true);
+    }
+  });
+
+  it('validates all osFamily enum values', () => {
+    for (const os of ['ios', 'android', 'macos', 'windows', 'linux', 'chromeos', 'other']) {
+      const result = TelemetryEventSchema.safeParse(validEvent({ osFamily: os }));
+      expect(result.success).toBe(true);
+    }
+  });
+
+  it('validates all eventType enum values', () => {
+    for (const et of ['debug', 'info', 'warn', 'error', 'fatal']) {
+      const result = TelemetryEventSchema.safeParse(validEvent({ eventType: et }));
+      expect(result.success).toBe(true);
+    }
+  });
+
+  it('validates all releaseChannel enum values', () => {
+    for (const rc of ['dev', 'beta', 'prod']) {
+      const result = TelemetryEventSchema.safeParse(validEvent({ releaseChannel: rc }));
+      expect(result.success).toBe(true);
+    }
+  });
+});
+
+// ─── TelemetryIngestRequestSchema ───────────────────────────────────
+
+describe('TelemetryIngestRequestSchema', () => {
+  it('accepts valid batch', () => {
+    const result = TelemetryIngestRequestSchema.safeParse({
+      productId: 'lysnrai',
+      events: [validEvent()],
+    });
+    expect(result.success).toBe(true);
+  });
+
+  it('rejects empty events array', () => {
+    const result = TelemetryIngestRequestSchema.safeParse({
+      productId: 'lysnrai',
+      events: [],
+    });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects > 50 events', () => {
+    const events = Array.from({ length: 51 }, (_, i) =>
+      validEvent({ id: `550e8400-e29b-41d4-a716-44665544${String(i).padStart(4, '0')}` })
+    );
+    const result = TelemetryIngestRequestSchema.safeParse({
+      productId: 'lysnrai',
+      events,
+    });
+    expect(result.success).toBe(false);
+  });
+
+  it('accepts clientClockSkewMs', () => {
+    const result = TelemetryIngestRequestSchema.safeParse({
+      productId: 'lysnrai',
+      events: [validEvent()],
+      clientClockSkewMs: -500,
+    });
+    expect(result.success).toBe(true);
+  });
+});
+
+// ─── CreatePolicySchema ─────────────────────────────────────────────
+
+describe('CreatePolicySchema', () => {
+  it('accepts minimal policy', () => {
+    const result = CreatePolicySchema.safeParse({ name: 'Test policy' });
+    expect(result.success).toBe(true);
+    if (result.success) {
+      expect(result.data.enabled).toBe(true);
+      expect(result.data.priority).toBe(50);
+      expect(result.data.eventTypes).toEqual(['warn', 'error', 'fatal']);
+      expect(result.data.samplingRate).toBe(1.0);
+    }
+  });
+
+  it('accepts full policy with targeting', () => {
+    const result = CreatePolicySchema.safeParse({
+      name: 'Debug iOS keyboard',
+      description: 'Debug user X iOS keyboard dictation',
+      enabled: true,
+      priority: 100,
+      eventTypes: ['debug', 'info', 'warn', 'error', 'fatal'],
+      modules: ['keyboard_dictation'],
+      samplingRate: 1.0,
+      targeting: {
+        userIds: ['usr_abc'],
+        platforms: ['ios'],
+        channels: ['keyboard_extension'],
+        osFamilies: ['ios'],
+        buildNumberRange: { min: 1, max: 25 },
+        countryCodes: ['US'],
+        regionCodes: ['US:WA'],
+        releaseChannels: ['beta'],
+        percentage: 100,
+      },
+      startsAt: '2026-02-17T00:00:00.000Z',
+      expiresAt: '2026-02-20T00:00:00.000Z',
+    });
+    expect(result.success).toBe(true);
+  });
+
+  it('rejects empty name', () => {
+    const result = CreatePolicySchema.safeParse({ name: '' });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects samplingRate > 1', () => {
+    const result = CreatePolicySchema.safeParse({ name: 'Test', samplingRate: 1.5 });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects priority > 999', () => {
+    const result = CreatePolicySchema.safeParse({ name: 'Test', priority: 1000 });
+    expect(result.success).toBe(false);
+  });
+});
+
+// ─── UpdatePolicySchema ─────────────────────────────────────────────
+
+describe('UpdatePolicySchema', () => {
+  it('accepts partial updates', () => {
+    const result = UpdatePolicySchema.safeParse({ enabled: false, priority: 10 });
+    expect(result.success).toBe(true);
+  });
+
+  it('accepts empty update', () => {
+    const result = UpdatePolicySchema.safeParse({});
+    expect(result.success).toBe(true);
+  });
+
+  it('accepts nullable startsAt/expiresAt (to clear them)', () => {
+    const result = UpdatePolicySchema.safeParse({ startsAt: null, expiresAt: null });
+    expect(result.success).toBe(true);
+  });
+});
+
+// ─── TelemetryQuerySchema ───────────────────────────────────────────
+
+describe('TelemetryQuerySchema', () => {
+  it('accepts empty query (defaults)', () => {
+    const result = TelemetryQuerySchema.safeParse({});
+    expect(result.success).toBe(true);
+    if (result.success) {
+      expect(result.data.limit).toBe(50);
+    }
+  });
+
+  it('accepts full filter set', () => {
+    const result = TelemetryQuerySchema.safeParse({
+      userId: 'usr_abc',
+      platform: 'ios',
+      channel: 'keyboard_extension',
+      module: 'keyboard_dictation',
+      eventType: 'error',
+      from: '2026-02-01T00:00:00.000Z',
+      to: '2026-02-17T23:59:59.000Z',
+      limit: 100,
+    });
+    expect(result.success).toBe(true);
+  });
+
+  it('rejects limit > 200', () => {
+    const result = TelemetryQuerySchema.safeParse({ limit: 201 });
+    expect(result.success).toBe(false);
+  });
+
+  it('coerces string limit to number', () => {
+    const result = TelemetryQuerySchema.safeParse({ limit: '25' });
+    expect(result.success).toBe(true);
+    if (result.success) {
+      expect(result.data.limit).toBe(25);
+    }
+  });
+});
diff --git a/services/platform-service/src/modules/telemetry/types.ts b/services/platform-service/src/modules/telemetry/types.ts
new file mode 100644
index 00000000..475caf41
--- /dev/null
+++ b/services/platform-service/src/modules/telemetry/types.ts
@@ -0,0 +1,255 @@
+/**
+ * Telemetry types — event schema, collection policies, and cluster types.
+ * See docs/WINDSURF/CLIENT_TELEMETRY_DESIGN.md for full design.
+ */
+
+import { z } from 'zod';
+
+// ─── Enums ──────────────────────────────────────────────────────────
+
+export const PlatformEnum = z.enum(['ios', 'android', 'web', 'desktop']);
+export const ChannelEnum = z.enum([
+  'mobile_app',
+  'keyboard_extension',
+  'web_app',
+  'desktop_app',
+  'backend_service',
+]);
+export const OsFamilyEnum = z.enum([
+  'ios',
+  'android',
+  'macos',
+  'windows',
+  'linux',
+  'chromeos',
+  'other',
+]);
+export const EventTypeEnum = z.enum(['debug', 'info', 'warn', 'error', 'fatal']);
+export const ReleaseChannelEnum = z.enum(['dev', 'beta', 'prod']);
+
+// ─── Telemetry Event ────────────────────────────────────────────────
+
+export const TelemetryEventSchema = z
+  .object({
+    // Identity
+    id: z.string().uuid(),
+    productId: z.string().min(1),
+    userId: z.string().optional(),
+    anonymousInstallId: z.string().uuid().optional(),
+    sessionId: z.string().min(1),
+    requestId: z.string().optional(),
+
+    // Source classification
+    platform: PlatformEnum,
+    channel: ChannelEnum,
+    osFamily: OsFamilyEnum,
+    osVersion: z.string().optional(),
+    deviceModel: z.string().optional(),
+    locale: z.string().optional(),
+    timezone: z.string().optional(),
+
+    // App release
+    appVersion: z.string().min(1),
+    buildNumber: z.string().min(1),
+    releaseChannel: ReleaseChannelEnum,
+
+    // Event semantics
+    eventType: EventTypeEnum,
+    module: z.string().min(1),
+    feature: z.string().optional(),
+    eventName: z.string().min(1),
+
+    // Error & diagnostics
+    errorDomain: z.string().optional(),
+    errorCode: z.string().optional(),
+    message: z.string().max(512).optional(),
+    stackTrace: z.string().max(8192).optional(),
+    fingerprint: z.string().optional(),
+
+    // Structured metadata
+    tags: z.record(z.string().max(128)).optional(),
+    metrics: z.record(z.number()).optional(),
+    context: z.record(z.unknown()).optional(),
+
+    // Timing (client provides occurredAt)
+    occurredAt: z.string().datetime(),
+  })
+  .refine(e => e.userId || e.anonymousInstallId, {
+    message: 'At least one of userId or anonymousInstallId is required',
+  });
+
+export type TelemetryEvent = z.infer<typeof TelemetryEventSchema>;
+
+/** Server-enriched event document stored in Cosmos. */
+export interface TelemetryEventDoc extends TelemetryEvent {
+  pk: string; // ${productId}:${yyyyMM}:${platform}
+  receivedAt: string;
+  ttl: number; // Cosmos TTL in seconds
+  countryCode?: string;
+  regionCode?: string;
+}
+
+// ─── Batch Ingest Request ───────────────────────────────────────────
+
+export const TelemetryIngestRequestSchema = z.object({
+  productId: z.string().min(1),
+  events: z.array(TelemetryEventSchema).min(1).max(50),
+  clientClockSkewMs: z.number().optional(),
+});
+
+export type TelemetryIngestRequest = z.infer<typeof TelemetryIngestRequestSchema>;
+
+export interface TelemetryIngestResponse {
+  accepted: number;
+  rejected: number;
+  errors?: Array<{ index: number; reason: string }>;
+  serverTime: string;
+}
+
+// ─── Collection Policy ──────────────────────────────────────────────
+
+export const TelemetryTargetingSchema = z.object({
+  userIds: z.array(z.string()).optional(),
+  anonymousInstallIds: z.array(z.string()).optional(),
+  platforms: z.array(PlatformEnum).optional(),
+  channels: z.array(ChannelEnum).optional(),
+  osFamilies: z.array(OsFamilyEnum).optional(),
+  appVersions: z.array(z.string()).optional(),
+  appVersionRange: z
+    .object({
+      min: z.string().optional(),
+      max: z.string().optional(),
+    })
+    .optional(),
+  buildNumbers: z.array(z.string()).optional(),
+  buildNumberRange: z
+    .object({
+      min: z.number().optional(),
+      max: z.number().optional(),
+    })
+    .optional(),
+  countryCodes: z.array(z.string()).optional(),
+  regionCodes: z.array(z.string()).optional(),
+  releaseChannels: z.array(ReleaseChannelEnum).optional(),
+  percentage: z.number().min(0).max(100).optional(),
+});
+
+export const CreatePolicySchema = z.object({
+  name: z.string().min(1).max(200),
+  description: z.string().default(''),
+  enabled: z.boolean().default(true),
+  priority: z.number().int().min(0).max(999).default(50),
+  eventTypes: z.array(EventTypeEnum).default(['warn', 'error', 'fatal']),
+  modules: z.array(z.string()).default([]),
+  samplingRate: z.number().min(0).max(1).default(1.0),
+  targeting: TelemetryTargetingSchema.default({}),
+  startsAt: z.string().datetime().optional(),
+  expiresAt: z.string().datetime().optional(),
+});
+
+export const UpdatePolicySchema = z.object({
+  name: z.string().min(1).max(200).optional(),
+  description: z.string().optional(),
+  enabled: z.boolean().optional(),
+  priority: z.number().int().min(0).max(999).optional(),
+  eventTypes: z.array(EventTypeEnum).optional(),
+  modules: z.array(z.string()).optional(),
+  samplingRate: z.number().min(0).max(1).optional(),
+  targeting: TelemetryTargetingSchema.optional(),
+  startsAt: z.string().datetime().optional().nullable(),
+  expiresAt: z.string().datetime().optional().nullable(),
+});
+
+export type CreatePolicyInput = z.infer<typeof CreatePolicySchema>;
+export type UpdatePolicyInput = z.infer<typeof UpdatePolicySchema>;
+
+export interface TelemetryCollectionPolicyDoc {
+  id: string;
+  productId: string;
+  name: string;
+  description: string;
+  enabled: boolean;
+  priority: number;
+  eventTypes: string[];
+  modules: string[];
+  samplingRate: number;
+  targeting: z.infer<typeof TelemetryTargetingSchema>;
+  startsAt?: string;
+  expiresAt?: string;
+  createdAt: string;
+  updatedAt: string;
+  createdBy: string;
+}
+
+// ─── Collection Config Response (for clients) ──────────────────────
+
+export interface TelemetryCollectionConfig {
+  enabled: boolean;
+  eventTypes: string[];
+  modules: string[];
+  samplingRates: {
+    debug: number;
+    info: number;
+    warn: number;
+    error: number;
+    fatal: number;
+  };
+  batchSize: number;
+  flushIntervalMs: number;
+  maxQueueSize: number;
+}
+
+// ─── Error Cluster ──────────────────────────────────────────────────
+
+export interface TelemetryErrorCluster {
+  id: string; // ${fingerprint}:${yyyyMM}
+  pk: string; // ${productId}:${platform}:${module}
+  productId: string;
+  fingerprint: string;
+
+  platform: string;
+  channel: string;
+  module: string;
+  eventName: string;
+
+  affectedVersions: Array<{
+    appVersion: string;
+    buildNumber: string;
+    count: number;
+    lastSeenAt: string;
+  }>;
+
+  firstSeenAt: string;
+  lastSeenAt: string;
+  totalCount: number;
+  affectedUserIds: string[];
+  affectedInstallIds: string[];
+  affectedOsFamilies: string[];
+
+  sampleErrorDomain?: string;
+  sampleErrorCode?: string;
+  sampleMessage?: string;
+  severity: 'warn' | 'error' | 'fatal';
+  ttl: number;
+}
+
+// ─── Query / Admin types ────────────────────────────────────────────
+
+export const TelemetryQuerySchema = z.object({
+  userId: z.string().optional(),
+  anonymousInstallId: z.string().optional(),
+  platform: z.string().optional(),
+  channel: z.string().optional(),
+  osFamily: z.string().optional(),
+  appVersion: z.string().optional(),
+  buildNumber: z.string().optional(),
+  module: z.string().optional(),
+  eventName: z.string().optional(),
+  eventType: z.string().optional(),
+  from: z.string().datetime().optional(),
+  to: z.string().datetime().optional(),
+  limit: z.coerce.number().int().min(1).max(200).default(50),
+  continuationToken: z.string().optional(),
+});
+
+export type TelemetryQueryInput = z.infer<typeof TelemetryQuerySchema>;
diff --git a/services/platform-service/src/server.ts b/services/platform-service/src/server.ts
index ed0007fc..88d7e21a 100644
--- a/services/platform-service/src/server.ts
+++ b/services/platform-service/src/server.ts
@@ -46,6 +46,7 @@ import { publicRoutes } from './modules/public/routes.js';
 import { tokenRoutes } from './modules/tokens/routes.js';
 import { themeRoutes } from './modules/themes/routes.js';
 import { waitlistRoutes } from './modules/waitlist/routes.js';
+import { telemetryRoutes } from './modules/telemetry/routes.js';
 import { initCosmosIfNeeded } from './lib/cosmos-init.js';
 import { config } from './lib/config.js';
 
@@ -116,6 +117,8 @@ await app.register(tokenRoutes, { prefix: '/api' });
 await app.register(themeRoutes, { prefix: '/api' });
 // Waitlist module (pre-launch signups — public + admin routes)
 await app.register(waitlistRoutes, { prefix: '/api' });
+// Telemetry module (client ingest + admin query + policies)
+await app.register(telemetryRoutes, { prefix: '/api' });
 // Public routes — no auth, registered at top level
 await app.register(publicRoutes, { prefix: '/api' });