diff --git a/services/platform-service/src/lib/cosmos-init.ts b/services/platform-service/src/lib/cosmos-init.ts
index 09ba48ab..7a080a4a 100644
--- a/services/platform-service/src/lib/cosmos-init.ts
+++ b/services/platform-service/src/lib/cosmos-init.ts
@@ -69,6 +69,13 @@ const CONTAINER_DEFS: Record<string, ContainerConfig> = {
   telemetry_events: { partitionKeyPath: '/pk', defaultTtl: 30 * 86400 },
   telemetry_error_clusters: { partitionKeyPath: '/pk', defaultTtl: 90 * 86400 },
   telemetry_collection_policies: { partitionKeyPath: '/productId' },
+  // P2 — Product Intelligence
+  experiments: { partitionKeyPath: '/id' },
+  experiment_assignments: { partitionKeyPath: '/experimentId' },
+  analytics_rollups: { partitionKeyPath: '/productId' },
+  feedback: { partitionKeyPath: '/productId' },
+  impersonation_sessions: { partitionKeyPath: '/productId', defaultTtl: 90 * 86400 },
+  changelog: { partitionKeyPath: '/productId' },
 };
 
 export async function initCosmosIfNeeded(): Promise<void> {
diff --git a/services/platform-service/src/modules/analytics/analytics.test.ts b/services/platform-service/src/modules/analytics/analytics.test.ts
new file mode 100644
index 00000000..84004245
--- /dev/null
+++ b/services/platform-service/src/modules/analytics/analytics.test.ts
@@ -0,0 +1,102 @@
+/**
+ * Analytics Rollups module — unit tests.
+ */
+
+import { describe, it, expect } from 'vitest';
+import { IngestMetricSchema, IngestBatchSchema, QueryRollupsSchema } from './types.js';
+import { toDailyKey, toWeeklyKey, toMonthlyKey, getDateKey } from './repository.js';
+
+// ── Schema Validation ────────────────────────────────────────
+
+describe('IngestMetricSchema', () => {
+  it('accepts valid metric with defaults', () => {
+    const result = IngestMetricSchema.parse({ metric: 'signups' });
+    expect(result.metric).toBe('signups');
+    expect(result.value).toBe(1);
+    expect(result.timestamp).toBeUndefined();
+  });
+
+  it('accepts metric with dots and underscores', () => {
+    const result = IngestMetricSchema.parse({ metric: 'user.session_start', value: 5 });
+    expect(result.metric).toBe('user.session_start');
+    expect(result.value).toBe(5);
+  });
+
+  it('rejects empty metric name', () => {
+    expect(() => IngestMetricSchema.parse({ metric: '' })).toThrow();
+  });
+
+  it('rejects metric with invalid chars', () => {
+    expect(() => IngestMetricSchema.parse({ metric: 'BAD-METRIC' })).toThrow();
+  });
+
+  it('accepts explicit timestamp', () => {
+    const result = IngestMetricSchema.parse({
+      metric: 'logins',
+      timestamp: '2026-01-15T10:00:00.000Z',
+    });
+    expect(result.timestamp).toBe('2026-01-15T10:00:00.000Z');
+  });
+});
+
+describe('IngestBatchSchema', () => {
+  it('accepts batch of events', () => {
+    const result = IngestBatchSchema.parse({
+      events: [
+        { metric: 'signups', value: 1 },
+        { metric: 'logins', value: 3 },
+      ],
+    });
+    expect(result.events).toHaveLength(2);
+  });
+
+  it('rejects empty batch', () => {
+    expect(() => IngestBatchSchema.parse({ events: [] })).toThrow();
+  });
+});
+
+describe('QueryRollupsSchema', () => {
+  it('accepts defaults', () => {
+    const result = QueryRollupsSchema.parse({});
+    expect(result.period).toBe('daily');
+  });
+
+  it('accepts all params', () => {
+    const result = QueryRollupsSchema.parse({
+      period: 'weekly',
+      from: '2026-01-01',
+      to: '2026-01-31',
+      metric: 'signups',
+    });
+    expect(result.period).toBe('weekly');
+    expect(result.metric).toBe('signups');
+  });
+
+  it('rejects invalid period', () => {
+    expect(() => QueryRollupsSchema.parse({ period: 'yearly' })).toThrow();
+  });
+});
+
+// ── Date Key Helpers ─────────────────────────────────────────
+
+describe('date key helpers', () => {
+  it('toDailyKey returns YYYY-MM-DD', () => {
+    expect(toDailyKey(new Date('2026-03-15T10:00:00Z'))).toBe('2026-03-15');
+  });
+
+  it('toMonthlyKey returns YYYY-MM', () => {
+    expect(toMonthlyKey(new Date('2026-03-15T10:00:00Z'))).toBe('2026-03');
+  });
+
+  it('toWeeklyKey returns YYYY-Www format', () => {
+    const key = toWeeklyKey(new Date('2026-03-15T10:00:00Z'));
+    expect(key).toMatch(/^2026-W\d{2}$/);
+  });
+
+  it('getDateKey dispatches correctly', () => {
+    const d = new Date('2026-06-01T12:00:00Z');
+    expect(getDateKey(d, 'daily')).toBe('2026-06-01');
+    expect(getDateKey(d, 'monthly')).toBe('2026-06');
+    expect(getDateKey(d, 'weekly')).toMatch(/^2026-W\d{2}$/);
+  });
+});
diff --git a/services/platform-service/src/modules/analytics/repository.ts b/services/platform-service/src/modules/analytics/repository.ts
new file mode 100644
index 00000000..be20c12f
--- /dev/null
+++ b/services/platform-service/src/modules/analytics/repository.ts
@@ -0,0 +1,144 @@
+/**
+ * Analytics Rollups repository — Cosmos DB CRUD + rollup logic.
+ */
+
+import { getRegisteredContainer } from '@bytelyst/cosmos';
+import type { AnalyticsRollupDoc, RollupPeriod, IngestMetricInput } from './types.js';
+
+function getContainer() {
+  return getRegisteredContainer('analytics_rollups');
+}
+
+// ── Date helpers ─────────────────────────────────────────────
+
+export function toDailyKey(date: Date): string {
+  return date.toISOString().slice(0, 10); // YYYY-MM-DD
+}
+
+export function toWeeklyKey(date: Date): string {
+  const jan1 = new Date(date.getFullYear(), 0, 1);
+  const dayOfYear = Math.ceil((date.getTime() - jan1.getTime()) / 86_400_000);
+  const weekNum = Math.ceil((dayOfYear + jan1.getDay()) / 7);
+  return `${date.getFullYear()}-W${String(weekNum).padStart(2, '0')}`;
+}
+
+export function toMonthlyKey(date: Date): string {
+  return date.toISOString().slice(0, 7); // YYYY-MM
+}
+
+export function getDateKey(date: Date, period: RollupPeriod): string {
+  switch (period) {
+    case 'daily':
+      return toDailyKey(date);
+    case 'weekly':
+      return toWeeklyKey(date);
+    case 'monthly':
+      return toMonthlyKey(date);
+  }
+}
+
+// ── Ingest ───────────────────────────────────────────────────
+
+export async function ingestMetric(productId: string, event: IngestMetricInput): Promise<void> {
+  const ts = event.timestamp ? new Date(event.timestamp) : new Date();
+  // Increment daily rollup (other periods aggregated by scheduled job)
+  await incrementRollup(productId, 'daily', toDailyKey(ts), event.metric, event.value);
+}
+
+export async function ingestBatch(productId: string, events: IngestMetricInput[]): Promise<number> {
+  let count = 0;
+  for (const event of events) {
+    await ingestMetric(productId, event);
+    count++;
+  }
+  return count;
+}
+
+// ── Rollup CRUD ──────────────────────────────────────────────
+
+async function incrementRollup(
+  productId: string,
+  period: RollupPeriod,
+  dateKey: string,
+  metric: string,
+  value: number
+): Promise<void> {
+  const id = `${productId}:${period}:${dateKey}`;
+  const container = getContainer();
+  const now = new Date().toISOString();
+
+  try {
+    const { resource } = await container.item(id, productId).read<AnalyticsRollupDoc>();
+    if (resource) {
+      resource.metrics[metric] = (resource.metrics[metric] ?? 0) + value;
+      resource.updatedAt = now;
+      await container.item(id, productId).replace(resource);
+      return;
+    }
+  } catch {
+    // Does not exist — create
+  }
+
+  const doc: AnalyticsRollupDoc = {
+    id,
+    productId,
+    period,
+    date: dateKey,
+    metrics: { [metric]: value },
+    createdAt: now,
+    updatedAt: now,
+  };
+  await container.items.create(doc);
+}
+
+export async function queryRollups(
+  productId: string,
+  period: RollupPeriod,
+  from?: string,
+  to?: string,
+  metric?: string
+): Promise<AnalyticsRollupDoc[]> {
+  const conditions = ['c.productId = @pid', 'c.period = @period'];
+  const params: { name: string; value: string }[] = [
+    { name: '@pid', value: productId },
+    { name: '@period', value: period },
+  ];
+
+  if (from) {
+    conditions.push('c.date >= @from');
+    params.push({ name: '@from', value: from });
+  }
+  if (to) {
+    conditions.push('c.date <= @to');
+    params.push({ name: '@to', value: to });
+  }
+
+  const query = `SELECT * FROM c WHERE ${conditions.join(' AND ')} ORDER BY c.date ASC`;
+  const { resources } = await getContainer()
+    .items.query<AnalyticsRollupDoc>({ query, parameters: params })
+    .fetchAll();
+
+  // Filter to specific metric if requested
+  if (metric) {
+    return resources.map(r => ({
+      ...r,
+      metrics: { [metric]: r.metrics[metric] ?? 0 },
+    }));
+  }
+
+  return resources;
+}
+
+export async function getRollup(
+  productId: string,
+  period: RollupPeriod,
+  dateKey: string
+): Promise<AnalyticsRollupDoc | null> {
+  const id = `${productId}:${period}:${dateKey}`;
+  try {
+    const { resource } = await getContainer().item(id, productId).read<AnalyticsRollupDoc>();
+    return resource ?? null;
+  } catch {
+    return null;
+  }
+}
diff --git a/services/platform-service/src/modules/analytics/routes.ts b/services/platform-service/src/modules/analytics/routes.ts
new file mode 100644
index 00000000..bf8daac0
--- /dev/null
+++ b/services/platform-service/src/modules/analytics/routes.ts
@@ -0,0 +1,50 @@
+/**
+ * Analytics Rollups routes.
+ * Authenticated: ingest metrics. Admin: query rollups.
+ */
+
+import type { FastifyInstance } from 'fastify';
+import { UnauthorizedError, ForbiddenError } from '../../lib/errors.js';
+import { getRequestProductId } from '../../lib/request-context.js';
+import { IngestMetricSchema, IngestBatchSchema, QueryRollupsSchema } from './types.js';
+import { ingestMetric, ingestBatch, queryRollups } from './repository.js';
+
+function requireAuth(req: { jwtPayload?: { sub: string; role?: string } }): string {
+  if (!req.jwtPayload?.sub) throw new UnauthorizedError('Authentication required');
+  return req.jwtPayload.sub;
+}
+
+function requireAdmin(req: { jwtPayload?: { sub: string; role?: string } }): void {
+  requireAuth(req);
+  if (req.jwtPayload?.role !== 'admin') throw new ForbiddenError('Admin access required');
+}
+
+export async function analyticsRoutes(app: FastifyInstance): Promise<void> {
+  // ── Ingest single metric ──────────────────────────────────
+  app.post('/analytics/ingest', async (req, reply) => {
+    requireAuth(req);
+    const productId = getRequestProductId(req);
+    const event = IngestMetricSchema.parse(req.body);
+    await ingestMetric(productId, event);
+    reply.status(202);
+    return { status: 'accepted' };
+  });
+
+  // ── Ingest batch ──────────────────────────────────────────
+  app.post('/analytics/ingest/batch', async (req, reply) => {
+    requireAuth(req);
+    const productId = getRequestProductId(req);
+    const { events } = IngestBatchSchema.parse(req.body);
+    const count = await ingestBatch(productId, events);
+    reply.status(202);
+    return { status: 'accepted', count };
+  });
+
+  // ── Admin: Query rollups ──────────────────────────────────
+  app.get('/analytics/rollups', async req => {
+    requireAdmin(req);
+    const productId = getRequestProductId(req);
+    const { period, from, to, metric } = QueryRollupsSchema.parse(req.query);
+    return queryRollups(productId, period, from, to, metric);
+  });
+}
diff --git a/services/platform-service/src/modules/analytics/types.ts b/services/platform-service/src/modules/analytics/types.ts
new file mode 100644
index 00000000..8e135d40
--- /dev/null
+++ b/services/platform-service/src/modules/analytics/types.ts
@@ -0,0 +1,52 @@
+/**
+ * Analytics Rollups module — types and schemas.
+ * Pre-aggregated daily/weekly/monthly metrics per product.
+ */
+
+import { z } from 'zod';
+
+export type RollupPeriod = 'daily' | 'weekly' | 'monthly';
+
+export interface AnalyticsRollupDoc {
+  id: string; // `${productId}:${period}:${date}`
+  productId: string;
+  period: RollupPeriod;
+  date: string; // YYYY-MM-DD (daily), YYYY-Www (weekly), YYYY-MM (monthly)
+  metrics: Record<string, number>;
+  createdAt: string;
+  updatedAt: string;
+}
+
+export interface MetricEvent {
+  productId: string;
+  metric: string; // e.g. 'signups', 'fasts_completed', 'timers_created'
+  value: number;
+  timestamp: string;
+}
+
+// ── Schemas ────────────────────────────────────────────────────
+
+export const IngestMetricSchema = z.object({
+  metric: z
+    .string()
+    .min(1)
+    .max(100)
+    .regex(/^[a-z0-9_.]+$/),
+  value: z.number().default(1),
+  timestamp: z.string().datetime().optional(),
+});
+
+export const IngestBatchSchema = z.object({
+  events: z.array(IngestMetricSchema).min(1).max(100),
+});
+
+export const QueryRollupsSchema = z.object({
+  period: z.enum(['daily', 'weekly', 'monthly']).default('daily'),
+  from: z.string().optional(), // YYYY-MM-DD
+  to: z.string().optional(), // YYYY-MM-DD
+  metric: z.string().optional(), // filter to specific metric
+});
+
+export type IngestMetricInput = z.infer<typeof IngestMetricSchema>;
+export type IngestBatchInput = z.infer<typeof IngestBatchSchema>;
+export type QueryRollupsInput = z.infer<typeof QueryRollupsSchema>;
diff --git a/services/platform-service/src/modules/changelog/changelog.test.ts b/services/platform-service/src/modules/changelog/changelog.test.ts
new file mode 100644
index 00000000..71561531
--- /dev/null
+++ b/services/platform-service/src/modules/changelog/changelog.test.ts
@@ -0,0 +1,98 @@
+/**
+ * Changelog module — unit tests.
+ */
+
+import { describe, it, expect } from 'vitest';
+import { CreateChangelogSchema, UpdateChangelogSchema } from './types.js';
+
+describe('CreateChangelogSchema', () => {
+  it('accepts valid entry', () => {
+    const result = CreateChangelogSchema.parse({
+      version: '1.2.0',
+      title: 'New Dashboard',
+      categories: ['feature'],
+    });
+    expect(result.version).toBe('1.2.0');
+    expect(result.body).toBe('');
+    expect(result.published).toBe(false);
+  });
+
+  it('accepts entry with all fields', () => {
+    const result = CreateChangelogSchema.parse({
+      version: '2.0.0',
+      title: 'Major Release',
+      body: '## Breaking Changes\n- New API format',
+      categories: ['feature', 'breaking'],
+      published: true,
+    });
+    expect(result.categories).toHaveLength(2);
+    expect(result.published).toBe(true);
+  });
+
+  it('rejects empty version', () => {
+    expect(() =>
+      CreateChangelogSchema.parse({ version: '', title: 'Test', categories: ['fix'] })
+    ).toThrow();
+  });
+
+  it('rejects empty title', () => {
+    expect(() =>
+      CreateChangelogSchema.parse({ version: '1.0.0', title: '', categories: ['fix'] })
+    ).toThrow();
+  });
+
+  it('rejects empty categories', () => {
+    expect(() =>
+      CreateChangelogSchema.parse({ version: '1.0.0', title: 'Test', categories: [] })
+    ).toThrow();
+  });
+
+  it('rejects invalid category', () => {
+    expect(() =>
+      CreateChangelogSchema.parse({ version: '1.0.0', title: 'Test', categories: ['unknown'] })
+    ).toThrow();
+  });
+
+  it('rejects title over 200 chars', () => {
+    expect(() =>
+      CreateChangelogSchema.parse({ version: '1.0.0', title: 'x'.repeat(201), categories: ['fix'] })
+    ).toThrow();
+  });
+
+  it('rejects body over 10000 chars', () => {
+    expect(() =>
+      CreateChangelogSchema.parse({
+        version: '1.0.0',
+        title: 'Test',
+        body: 'x'.repeat(10001),
+        categories: ['fix'],
+      })
+    ).toThrow();
+  });
+});
+
+describe('UpdateChangelogSchema', () => {
+  it('accepts partial update', () => {
+    const result = UpdateChangelogSchema.parse({ title: 'Updated Title' });
+    expect(result.title).toBe('Updated Title');
+    expect(result.version).toBeUndefined();
+  });
+
+  it('accepts publish toggle', () => {
+    const result = UpdateChangelogSchema.parse({ published: true });
+    expect(result.published).toBe(true);
+  });
+
+  it('accepts category update', () => {
+    const result = UpdateChangelogSchema.parse({ categories: ['fix', 'security'] });
+    expect(result.categories).toEqual(['fix', 'security']);
+  });
+
+  it('rejects invalid category in update', () => {
+    expect(() => UpdateChangelogSchema.parse({ categories: ['invalid'] })).toThrow();
+  });
+
+  it('rejects empty categories array in update', () => {
+    expect(() => UpdateChangelogSchema.parse({ categories: [] })).toThrow();
+  });
+});
diff --git a/services/platform-service/src/modules/changelog/repository.ts b/services/platform-service/src/modules/changelog/repository.ts
new file mode 100644
index 00000000..f4066242
--- /dev/null
+++ b/services/platform-service/src/modules/changelog/repository.ts
@@ -0,0 +1,93 @@
+/**
+ * Changelog repository — Cosmos DB CRUD.
+ */
+
+import { getRegisteredContainer } from '@bytelyst/cosmos';
+import type { ChangelogEntryDoc, CreateChangelogInput, UpdateChangelogInput } from './types.js';
+
+function getContainer() {
+  return getRegisteredContainer('changelog');
+}
+
+export async function createEntry(
+  productId: string,
+  input: CreateChangelogInput
+): Promise<ChangelogEntryDoc> {
+  const now = new Date().toISOString();
+  const doc: ChangelogEntryDoc = {
+    id: `cl-${Date.now()}-${Math.random().toString(36).slice(2, 8)}`,
+    productId,
+    version: input.version,
+    title: input.title,
+    body: input.body ?? '',
+    categories: input.categories,
+    published: input.published ?? false,
+    publishedAt: input.published ? now : null,
+    createdAt: now,
+    updatedAt: now,
+  };
+  await getContainer().items.create(doc);
+  return doc;
+}
+
+export async function getEntry(id: string, productId: string): Promise<ChangelogEntryDoc | null> {
+  try {
+    const { resource } = await getContainer().item(id, productId).read<ChangelogEntryDoc>();
+    return resource ?? null;
+  } catch {
+    return null;
+  }
+}
+
+export async function listEntries(
+  productId: string,
+  publishedOnly: boolean = false
+): Promise<ChangelogEntryDoc[]> {
+  const conditions = ['c.productId = @pid'];
+  if (publishedOnly) conditions.push('c.published = true');
+
+  const { resources } = await getContainer()
+    .items.query<ChangelogEntryDoc>({
+      query: `SELECT * FROM c WHERE ${conditions.join(' AND ')} ORDER BY c.createdAt DESC`,
+      parameters: [{ name: '@pid', value: productId }],
+    })
+    .fetchAll();
+  return resources;
+}
+
+export async function updateEntry(
+  id: string,
+  productId: string,
+  updates: UpdateChangelogInput
+): Promise<ChangelogEntryDoc | null> {
+  const existing = await getEntry(id, productId);
+  if (!existing) return null;
+
+  const now = new Date().toISOString();
+  const updated: ChangelogEntryDoc = {
+    ...existing,
+    ...updates,
+    updatedAt: now,
+  };
+
+  // Set publishedAt on first publish
+  if (updates.published === true && !existing.publishedAt) {
+    updated.publishedAt = now;
+  }
+  // Clear publishedAt on unpublish
+  if (updates.published === false) {
+    updated.publishedAt = null;
+  }
+
+  await getContainer().item(id, productId).replace(updated);
+  return updated;
+}
+
+export async function deleteEntry(id: string, productId: string): Promise<boolean> {
+  try {
+    await getContainer().item(id, productId).delete();
+    return true;
+  } catch {
+    return false;
+  }
+}
diff --git a/services/platform-service/src/modules/changelog/routes.ts b/services/platform-service/src/modules/changelog/routes.ts
new file mode 100644
index 00000000..c38c80b0
--- /dev/null
+++ b/services/platform-service/src/modules/changelog/routes.ts
@@ -0,0 +1,68 @@
+/**
+ * Changelog routes.
+ * Public: list published entries. Admin: CRUD all entries.
+ */
+
+import type { FastifyInstance } from 'fastify';
+import { UnauthorizedError, ForbiddenError, NotFoundError } from '../../lib/errors.js';
+import { getRequestProductId, getRequestProductIdForPublic } from '../../lib/request-context.js';
+import { CreateChangelogSchema, UpdateChangelogSchema } from './types.js';
+import { createEntry, getEntry, listEntries, updateEntry, deleteEntry } from './repository.js';
+
+function requireAdmin(req: { jwtPayload?: { sub: string; role?: string } }): string {
+  if (!req.jwtPayload?.sub) throw new UnauthorizedError('Authentication required');
+  if (req.jwtPayload.role !== 'admin') throw new ForbiddenError('Admin access required');
+  return req.jwtPayload.sub;
+}
+
+export async function changelogRoutes(app: FastifyInstance): Promise<void> {
+  // ── Public: List published changelog ──────────────────────
+  app.get('/changelog', async req => {
+    const productId = getRequestProductIdForPublic(req);
+    return listEntries(productId, true);
+  });
+
+  // ── Public: Get single entry ──────────────────────────────
+  app.get<{ Params: { id: string } }>('/changelog/:id', async req => {
+    const productId = getRequestProductIdForPublic(req);
+    const entry = await getEntry(req.params.id, productId);
+    if (!entry || !entry.published) throw new NotFoundError('Changelog entry not found');
+    return entry;
+  });
+
+  // ── Admin: List all entries (including drafts) ────────────
+  app.get('/admin/changelog', async req => {
+    requireAdmin(req);
+    const productId = getRequestProductId(req);
+    return listEntries(productId, false);
+  });
+
+  // ── Admin: Create entry ───────────────────────────────────
+  app.post('/admin/changelog', async (req, reply) => {
+    requireAdmin(req);
+    const productId = getRequestProductId(req);
+    const input = CreateChangelogSchema.parse(req.body);
+    const entry = await createEntry(productId, input);
+    reply.status(201);
+    return entry;
+  });
+
+  // ── Admin: Update entry ───────────────────────────────────
+  app.put<{ Params: { id: string } }>('/admin/changelog/:id', async req => {
+    requireAdmin(req);
+    const productId = getRequestProductId(req);
+    const updates = UpdateChangelogSchema.parse(req.body);
+    const entry = await updateEntry(req.params.id, productId, updates);
+    if (!entry) throw new NotFoundError('Changelog entry not found');
+    return entry;
+  });
+
+  // ── Admin: Delete entry ───────────────────────────────────
+  app.delete<{ Params: { id: string } }>('/admin/changelog/:id', async (req, reply) => {
+    requireAdmin(req);
+    const productId = getRequestProductId(req);
+    const ok = await deleteEntry(req.params.id, productId);
+    if (!ok) throw new NotFoundError('Changelog entry not found');
+    reply.status(204);
+  });
+}
diff --git a/services/platform-service/src/modules/changelog/types.ts b/services/platform-service/src/modules/changelog/types.ts
new file mode 100644
index 00000000..e12cb161
--- /dev/null
+++ b/services/platform-service/src/modules/changelog/types.ts
@@ -0,0 +1,45 @@
+/**
+ * Changelog module — types and schemas.
+ * Public product changelog entries managed by admins.
+ */
+
+import { z } from 'zod';
+
+export type ChangelogCategory = 'feature' | 'improvement' | 'fix' | 'breaking' | 'security';
+
+export interface ChangelogEntryDoc {
+  id: string;
+  productId: string;
+  version: string; // semver: '1.2.0'
+  title: string;
+  body: string; // markdown
+  categories: ChangelogCategory[];
+  published: boolean;
+  publishedAt: string | null;
+  createdAt: string;
+  updatedAt: string;
+}
+
+// ── Schemas ────────────────────────────────────────────────────
+
+export const CreateChangelogSchema = z.object({
+  version: z.string().min(1).max(50),
+  title: z.string().min(1).max(200),
+  body: z.string().max(10000).default(''),
+  categories: z.array(z.enum(['feature', 'improvement', 'fix', 'breaking', 'security'])).min(1),
+  published: z.boolean().default(false),
+});
+
+export const UpdateChangelogSchema = z.object({
+  version: z.string().min(1).max(50).optional(),
+  title: z.string().min(1).max(200).optional(),
+  body: z.string().max(10000).optional(),
+  categories: z
+    .array(z.enum(['feature', 'improvement', 'fix', 'breaking', 'security']))
+    .min(1)
+    .optional(),
+  published: z.boolean().optional(),
+});
+
+export type CreateChangelogInput = z.infer<typeof CreateChangelogSchema>;
+export type UpdateChangelogInput = z.infer<typeof UpdateChangelogSchema>;
diff --git a/services/platform-service/src/modules/experiments/experiments.test.ts b/services/platform-service/src/modules/experiments/experiments.test.ts
new file mode 100644
index 00000000..1e576e18
--- /dev/null
+++ b/services/platform-service/src/modules/experiments/experiments.test.ts
@@ -0,0 +1,141 @@
+/**
+ * A/B Testing (Experiments) module — unit tests.
+ */
+
+import { describe, it, expect } from 'vitest';
+import { CreateExperimentSchema, UpdateExperimentSchema } from './types.js';
+import { assignVariant } from './repository.js';
+
+// ── Schema Validation ────────────────────────────────────────
+
+describe('CreateExperimentSchema', () => {
+  const validInput = {
+    key: 'onboarding_v2',
+    name: 'Onboarding Flow V2',
+    variants: [
+      { key: 'control', weight: 50 },
+      { key: 'variant_a', weight: 50 },
+    ],
+  };
+
+  it('accepts valid input with defaults', () => {
+    const result = CreateExperimentSchema.parse(validInput);
+    expect(result.key).toBe('onboarding_v2');
+    expect(result.description).toBe('');
+    expect(result.targetSegments).toEqual([]);
+    expect(result.trafficPercent).toBe(100);
+  });
+
+  it('rejects key with invalid chars', () => {
+    expect(() => CreateExperimentSchema.parse({ ...validInput, key: 'BAD-KEY' })).toThrow();
+  });
+
+  it('rejects fewer than 2 variants', () => {
+    expect(() =>
+      CreateExperimentSchema.parse({
+        ...validInput,
+        variants: [{ key: 'only', weight: 100 }],
+      })
+    ).toThrow();
+  });
+
+  it('rejects variant weights not summing to 100', () => {
+    expect(() =>
+      CreateExperimentSchema.parse({
+        ...validInput,
+        variants: [
+          { key: 'a', weight: 40 },
+          { key: 'b', weight: 40 },
+        ],
+      })
+    ).toThrow(/sum to 100/);
+  });
+
+  it('accepts 3 variants summing to 100', () => {
+    const result = CreateExperimentSchema.parse({
+      ...validInput,
+      variants: [
+        { key: 'control', weight: 34 },
+        { key: 'a', weight: 33 },
+        { key: 'b', weight: 33 },
+      ],
+    });
+    expect(result.variants).toHaveLength(3);
+  });
+
+  it('accepts trafficPercent between 1 and 100', () => {
+    const result = CreateExperimentSchema.parse({ ...validInput, trafficPercent: 50 });
+    expect(result.trafficPercent).toBe(50);
+  });
+
+  it('rejects trafficPercent of 0', () => {
+    expect(() => CreateExperimentSchema.parse({ ...validInput, trafficPercent: 0 })).toThrow();
+  });
+});
+
+describe('UpdateExperimentSchema', () => {
+  it('accepts partial updates', () => {
+    const result = UpdateExperimentSchema.parse({ name: 'New Name' });
+    expect(result.name).toBe('New Name');
+    expect(result.status).toBeUndefined();
+  });
+
+  it('accepts status transition', () => {
+    const result = UpdateExperimentSchema.parse({ status: 'running' });
+    expect(result.status).toBe('running');
+  });
+
+  it('rejects invalid status', () => {
+    expect(() => UpdateExperimentSchema.parse({ status: 'invalid' })).toThrow();
+  });
+});
+
+// ── Deterministic Assignment ─────────────────────────────────
+
+describe('assignVariant', () => {
+  const variants = [
+    { key: 'control', weight: 50, description: '' },
+    { key: 'variant_a', weight: 50, description: '' },
+  ];
+
+  it('assigns deterministically — same input = same output', () => {
+    const v1 = assignVariant('exp-1', 'user-a', variants);
+    const v2 = assignVariant('exp-1', 'user-a', variants);
+    expect(v1).toBe(v2);
+  });
+
+  it('distributes across variants for different users', () => {
+    const assignments = new Set<string>();
+    for (let i = 0; i < 100; i++) {
+      assignments.add(assignVariant('exp-1', `user-${i}`, variants));
+    }
+    // With 50/50 split and 100 users, both variants should appear
+    expect(assignments.size).toBe(2);
+  });
+
+  it('respects uneven weights', () => {
+    const unevenVariants = [
+      { key: 'control', weight: 90, description: '' },
+      { key: 'variant_a', weight: 10, description: '' },
+    ];
+    let controlCount = 0;
+    for (let i = 0; i < 1000; i++) {
+      if (assignVariant('exp-2', `u-${i}`, unevenVariants) === 'control') controlCount++;
+    }
+    // Should be roughly 90% control (allow wide margin for hash distribution)
+    expect(controlCount).toBeGreaterThan(700);
+    expect(controlCount).toBeLessThan(990);
+  });
+
+  it('different experiments give different assignments for same user', () => {
+    // Not guaranteed but statistically likely with enough samples
+    let sameCount = 0;
+    for (let i = 0; i < 50; i++) {
+      const v1 = assignVariant(`exp-a-${i}`, 'user-x', variants);
+      const v2 = assignVariant(`exp-b-${i}`, 'user-x', variants);
+      if (v1 === v2) sameCount++;
+    }
+    // Should not be all the same (statistically near-impossible)
+    expect(sameCount).toBeLessThan(50);
+  });
+});
diff --git a/services/platform-service/src/modules/experiments/repository.ts b/services/platform-service/src/modules/experiments/repository.ts
new file mode 100644
index 00000000..770a0823
--- /dev/null
+++ b/services/platform-service/src/modules/experiments/repository.ts
@@ -0,0 +1,178 @@
+/**
+ * A/B Testing (Experiments) repository — Cosmos DB CRUD.
+ */
+
+import { getRegisteredContainer } from '@bytelyst/cosmos';
+import type {
+  ExperimentDoc,
+  ExperimentAssignmentDoc,
+  CreateExperimentInput,
+  UpdateExperimentInput,
+} from './types.js';
+
+function getContainer() {
+  return getRegisteredContainer('experiments');
+}
+
+function getAssignmentContainer() {
+  return getRegisteredContainer('experiment_assignments');
+}
+
+// ── FNV-1a hash for deterministic assignment ──────────────────
+
+function fnv1a(str: string): number {
+  let hash = 0x811c9dc5;
+  for (let i = 0; i < str.length; i++) {
+    hash ^= str.charCodeAt(i);
+    hash = (hash * 0x01000193) >>> 0;
+  }
+  return hash;
+}
+
+export function assignVariant(
+  experimentId: string,
+  userId: string,
+  variants: ExperimentDoc['variants']
+): string {
+  const hash = fnv1a(`${experimentId}:${userId}`);
+  const bucket = hash % 100;
+  let cumulative = 0;
+  for (const v of variants) {
+    cumulative += v.weight;
+    if (bucket < cumulative) return v.key;
+  }
+  return variants[variants.length - 1].key;
+}
+
+// ── Experiment CRUD ──────────────────────────────────────────
+
+export async function listExperiments(productId: string): Promise<ExperimentDoc[]> {
+  const container = getContainer();
+  const { resources } = await container.items
+    .query<ExperimentDoc>({
+      query: 'SELECT * FROM c WHERE c.productId = @pid ORDER BY c.createdAt DESC',
+      parameters: [{ name: '@pid', value: productId }],
+    })
+    .fetchAll();
+  return resources;
+}
+
+export async function getExperiment(id: string): Promise<ExperimentDoc | null> {
+  try {
+    const { resource } = await getContainer().item(id, id).read<ExperimentDoc>();
+    return resource ?? null;
+  } catch {
+    return null;
+  }
+}
+
+export async function createExperiment(
+  productId: string,
+  input: CreateExperimentInput
+): Promise<ExperimentDoc> {
+  const now = new Date().toISOString();
+  const doc: ExperimentDoc = {
+    id: `exp-${Date.now()}-${Math.random().toString(36).slice(2, 8)}`,
+    productId,
+    key: input.key,
+    name: input.name,
+    description: input.description ?? '',
+    status: 'draft',
+    variants: input.variants.map(v => ({
+      key: v.key,
+      weight: v.weight,
+      description: v.description ?? '',
+    })),
+    targetSegments: input.targetSegments ?? [],
+    trafficPercent: input.trafficPercent ?? 100,
+    startedAt: null,
+    endedAt: null,
+    createdAt: now,
+    updatedAt: now,
+  };
+  await getContainer().items.create(doc);
+  return doc;
+}
+
+export async function updateExperiment(
+  id: string,
+  updates: UpdateExperimentInput
+): Promise<ExperimentDoc | null> {
+  const existing = await getExperiment(id);
+  if (!existing) return null;
+
+  const now = new Date().toISOString();
+  const updated: ExperimentDoc = {
+    ...existing,
+    ...updates,
+    updatedAt: now,
+  };
+
+  if (updates.status === 'running' && !existing.startedAt) {
+    updated.startedAt = now;
+  }
+  if (updates.status === 'completed' && !existing.endedAt) {
+    updated.endedAt = now;
+  }
+
+  await getContainer().item(id, id).replace(updated);
+  return updated;
+}
+
+export async function deleteExperiment(id: string): Promise<boolean> {
+  try {
+    await getContainer().item(id, id).delete();
+    return true;
+  } catch {
+    return false;
+  }
+}
+
+// ── Assignments ──────────────────────────────────────────────
+
+export async function getAssignment(
+  experimentId: string,
+  userId: string
+): Promise<ExperimentAssignmentDoc | null> {
+  const id = `${experimentId}:${userId}`;
+  try {
+    const { resource } = await getAssignmentContainer()
+      .item(id, experimentId)
+      .read<ExperimentAssignmentDoc>();
+    return resource ?? null;
+  } catch {
+    return null;
+  }
+}
+
+export async function getOrCreateAssignment(
+  experiment: ExperimentDoc,
+  userId: string
+): Promise<ExperimentAssignmentDoc> {
+  const existing = await getAssignment(experiment.id, userId);
+  if (existing) return existing;
+
+  const variantKey = assignVariant(experiment.id, userId, experiment.variants);
+  const doc: ExperimentAssignmentDoc = {
+    id: `${experiment.id}:${userId}`,
+    productId: experiment.productId,
+    experimentId: experiment.id,
+    userId,
+    variantKey,
+    assignedAt: new Date().toISOString(),
+  };
+  await getAssignmentContainer().items.create(doc);
+  return doc;
+}
+
+export async function listAssignmentsForExperiment(
+  experimentId: string
+): Promise<ExperimentAssignmentDoc[]> {
+  const { resources } = await getAssignmentContainer()
+    .items.query<ExperimentAssignmentDoc>({
+      query: 'SELECT * FROM c WHERE c.experimentId = @eid',
+      parameters: [{ name: '@eid', value: experimentId }],
+    })
+    .fetchAll();
+  return resources;
+}
diff --git a/services/platform-service/src/modules/experiments/routes.ts b/services/platform-service/src/modules/experiments/routes.ts
new file mode 100644
index 00000000..d57dedd4
--- /dev/null
+++ b/services/platform-service/src/modules/experiments/routes.ts
@@ -0,0 +1,89 @@
+/**
+ * A/B Testing (Experiments) routes.
+ * Admin: CRUD experiments. Authenticated users: get their variant assignment.
+ */
+
+import type { FastifyInstance } from 'fastify';
+import { UnauthorizedError, ForbiddenError, NotFoundError } from '../../lib/errors.js';
+import { getRequestProductId } from '../../lib/request-context.js';
+import { CreateExperimentSchema, UpdateExperimentSchema } from './types.js';
+import {
+  listExperiments,
+  getExperiment,
+  createExperiment,
+  updateExperiment,
+  deleteExperiment,
+  getOrCreateAssignment,
+  listAssignmentsForExperiment,
+} from './repository.js';
+
+function requireAuth(req: { jwtPayload?: { sub: string; role?: string } }): string {
+  if (!req.jwtPayload?.sub) throw new UnauthorizedError('Authentication required');
+  return req.jwtPayload.sub;
+}
+
+function requireAdmin(req: { jwtPayload?: { sub: string; role?: string } }): void {
+  requireAuth(req);
+  if (req.jwtPayload?.role !== 'admin') throw new ForbiddenError('Admin access required');
+}
+
+export async function experimentRoutes(app: FastifyInstance): Promise<void> {
+  // ── Admin: List experiments ────────────────────────────────
+  app.get('/experiments', async req => {
+    requireAdmin(req);
+    const productId = getRequestProductId(req);
+    return listExperiments(productId);
+  });
+
+  // ── Admin: Get experiment ─────────────────────────────────
+  app.get<{ Params: { id: string } }>('/experiments/:id', async req => {
+    requireAdmin(req);
+    const experiment = await getExperiment(req.params.id);
+    if (!experiment) throw new NotFoundError('Experiment not found');
+    return experiment;
+  });
+
+  // ── Admin: Create experiment ──────────────────────────────
+  app.post('/experiments', async (req, reply) => {
+    requireAdmin(req);
+    const productId = getRequestProductId(req);
+    const input = CreateExperimentSchema.parse(req.body);
+    const experiment = await createExperiment(productId, input);
+    reply.status(201);
+    return experiment;
+  });
+
+  // ── Admin: Update experiment ──────────────────────────────
+  app.put<{ Params: { id: string } }>('/experiments/:id', async req => {
+    requireAdmin(req);
+    const updates = UpdateExperimentSchema.parse(req.body);
+    const experiment = await updateExperiment(req.params.id, updates);
+    if (!experiment) throw new NotFoundError('Experiment not found');
+    return experiment;
+  });
+
+  // ── Admin: Delete experiment ──────────────────────────────
+  app.delete<{ Params: { id: string } }>('/experiments/:id', async (req, reply) => {
+    requireAdmin(req);
+    const ok = await deleteExperiment(req.params.id);
+    if (!ok) throw new NotFoundError('Experiment not found');
+    reply.status(204);
+  });
+
+  // ── Admin: List assignments for experiment ────────────────
+  app.get<{ Params: { id: string } }>('/experiments/:id/assignments', async req => {
+    requireAdmin(req);
+    return listAssignmentsForExperiment(req.params.id);
+  });
+
+  // ── User: Get my variant for an experiment ────────────────
+  app.get<{ Params: { key: string } }>('/experiments/assign/:key', async req => {
+    const userId = requireAuth(req);
+    const productId = getRequestProductId(req);
+    const experiments = await listExperiments(productId);
+    const experiment = experiments.find(e => e.key === req.params.key && e.status === 'running');
+    if (!experiment) throw new NotFoundError('Experiment not found or not running');
+    const assignment = await getOrCreateAssignment(experiment, userId);
+    return { experimentKey: experiment.key, variant: assignment.variantKey };
+  });
+}
diff --git a/services/platform-service/src/modules/experiments/types.ts b/services/platform-service/src/modules/experiments/types.ts
new file mode 100644
index 00000000..4508e702
--- /dev/null
+++ b/services/platform-service/src/modules/experiments/types.ts
@@ -0,0 +1,78 @@
+/**
+ * A/B Testing (Experiments) module — types and schemas.
+ * Deterministic variant assignment via FNV-1a hash (same as feature flags).
+ */
+
+import { z } from 'zod';
+
+export type ExperimentStatus = 'draft' | 'running' | 'paused' | 'completed';
+
+export interface ExperimentVariant {
+  key: string; // e.g. 'control', 'variant_a', 'variant_b'
+  weight: number; // 0–100, must sum to 100
+  description: string;
+}
+
+export interface ExperimentDoc {
+  id: string;
+  productId: string;
+  key: string; // unique slug: 'onboarding_flow_v2'
+  name: string;
+  description: string;
+  status: ExperimentStatus;
+  variants: ExperimentVariant[];
+  targetSegments: string[]; // optional user segments
+  trafficPercent: number; // 0–100 — % of eligible users enrolled
+  startedAt: string | null;
+  endedAt: string | null;
+  createdAt: string;
+  updatedAt: string;
+}
+
+export interface ExperimentAssignmentDoc {
+  id: string; // `${experimentId}:${userId}`
+  productId: string;
+  experimentId: string;
+  userId: string;
+  variantKey: string;
+  assignedAt: string;
+}
+
+// ── Schemas ────────────────────────────────────────────────────
+
+const VariantSchema = z.object({
+  key: z
+    .string()
+    .min(1)
+    .regex(/^[a-z0-9_]+$/),
+  weight: z.number().int().min(0).max(100),
+  description: z.string().default(''),
+});
+
+export const CreateExperimentSchema = z
+  .object({
+    key: z
+      .string()
+      .min(1)
+      .regex(/^[a-z0-9_]+$/),
+    name: z.string().min(1).max(200),
+    description: z.string().default(''),
+    variants: z.array(VariantSchema).min(2).max(10),
+    targetSegments: z.array(z.string()).default([]),
+    trafficPercent: z.number().int().min(1).max(100).default(100),
+  })
+  .refine(d => d.variants.reduce((s, v) => s + v.weight, 0) === 100, {
+    message: 'Variant weights must sum to 100',
+    path: ['variants'],
+  });
+
+export const UpdateExperimentSchema = z.object({
+  name: z.string().min(1).max(200).optional(),
+  description: z.string().optional(),
+  status: z.enum(['draft', 'running', 'paused', 'completed']).optional(),
+  targetSegments: z.array(z.string()).optional(),
+  trafficPercent: z.number().int().min(1).max(100).optional(),
+});
+
+export type CreateExperimentInput = z.infer<typeof CreateExperimentSchema>;
+export type UpdateExperimentInput = z.infer<typeof UpdateExperimentSchema>;
diff --git a/services/platform-service/src/modules/feedback/feedback.test.ts b/services/platform-service/src/modules/feedback/feedback.test.ts
new file mode 100644
index 00000000..67107ecd
--- /dev/null
+++ b/services/platform-service/src/modules/feedback/feedback.test.ts
@@ -0,0 +1,105 @@
+/**
+ * In-App Feedback module — unit tests.
+ */
+
+import { describe, it, expect } from 'vitest';
+import { CreateFeedbackSchema, UpdateFeedbackSchema, QueryFeedbackSchema } from './types.js';
+
+describe('CreateFeedbackSchema', () => {
+  it('accepts valid bug report', () => {
+    const result = CreateFeedbackSchema.parse({
+      type: 'bug',
+      title: 'App crashes on timer start',
+      body: 'When I tap start, the app freezes',
+    });
+    expect(result.type).toBe('bug');
+    expect(result.title).toBe('App crashes on timer start');
+    expect(result.rating).toBeNull();
+    expect(result.screen).toBeNull();
+  });
+
+  it('accepts feature request with rating', () => {
+    const result = CreateFeedbackSchema.parse({
+      type: 'feature',
+      title: 'Dark mode',
+      rating: 4,
+      platform: 'ios',
+    });
+    expect(result.rating).toBe(4);
+    expect(result.platform).toBe('ios');
+  });
+
+  it('accepts praise with screen info', () => {
+    const result = CreateFeedbackSchema.parse({
+      type: 'praise',
+      title: 'Love the timer!',
+      screen: '/dashboard',
+      appVersion: '1.2.0',
+    });
+    expect(result.screen).toBe('/dashboard');
+    expect(result.appVersion).toBe('1.2.0');
+  });
+
+  it('rejects empty title', () => {
+    expect(() => CreateFeedbackSchema.parse({ type: 'bug', title: '' })).toThrow();
+  });
+
+  it('rejects invalid type', () => {
+    expect(() => CreateFeedbackSchema.parse({ type: 'complaint', title: 'test' })).toThrow();
+  });
+
+  it('rejects rating out of range', () => {
+    expect(() => CreateFeedbackSchema.parse({ type: 'praise', title: 'ok', rating: 0 })).toThrow();
+    expect(() => CreateFeedbackSchema.parse({ type: 'praise', title: 'ok', rating: 6 })).toThrow();
+  });
+
+  it('rejects title over 200 chars', () => {
+    expect(() => CreateFeedbackSchema.parse({ type: 'bug', title: 'x'.repeat(201) })).toThrow();
+  });
+});
+
+describe('UpdateFeedbackSchema', () => {
+  it('accepts status change', () => {
+    const result = UpdateFeedbackSchema.parse({ status: 'reviewed' });
+    expect(result.status).toBe('reviewed');
+  });
+
+  it('accepts admin notes', () => {
+    const result = UpdateFeedbackSchema.parse({ adminNotes: 'Tracked in JIRA-123' });
+    expect(result.adminNotes).toBe('Tracked in JIRA-123');
+  });
+
+  it('accepts null admin notes', () => {
+    const result = UpdateFeedbackSchema.parse({ adminNotes: null });
+    expect(result.adminNotes).toBeNull();
+  });
+
+  it('rejects invalid status', () => {
+    expect(() => UpdateFeedbackSchema.parse({ status: 'closed' })).toThrow();
+  });
+});
+
+describe('QueryFeedbackSchema', () => {
+  it('applies defaults', () => {
+    const result = QueryFeedbackSchema.parse({});
+    expect(result.limit).toBe(50);
+    expect(result.offset).toBe(0);
+  });
+
+  it('accepts all filters', () => {
+    const result = QueryFeedbackSchema.parse({
+      type: 'bug',
+      status: 'new',
+      limit: '20',
+      offset: '10',
+    });
+    expect(result.type).toBe('bug');
+    expect(result.status).toBe('new');
+    expect(result.limit).toBe(20);
+    expect(result.offset).toBe(10);
+  });
+
+  it('rejects limit over 100', () => {
+    expect(() => QueryFeedbackSchema.parse({ limit: '101' })).toThrow();
+  });
+});
diff --git a/services/platform-service/src/modules/feedback/repository.ts b/services/platform-service/src/modules/feedback/repository.ts
new file mode 100644
index 00000000..5f1cbf1e
--- /dev/null
+++ b/services/platform-service/src/modules/feedback/repository.ts
@@ -0,0 +1,118 @@
+/**
+ * In-App Feedback repository — Cosmos DB CRUD.
+ */
+
+import { getRegisteredContainer } from '@bytelyst/cosmos';
+import type {
+  FeedbackDoc,
+  CreateFeedbackInput,
+  UpdateFeedbackInput,
+  QueryFeedbackInput,
+} from './types.js';
+
+function getContainer() {
+  return getRegisteredContainer('feedback');
+}
+
+export async function createFeedback(
+  productId: string,
+  userId: string,
+  input: CreateFeedbackInput
+): Promise<FeedbackDoc> {
+  const now = new Date().toISOString();
+  const doc: FeedbackDoc = {
+    id: `fb-${Date.now()}-${Math.random().toString(36).slice(2, 8)}`,
+    productId,
+    userId,
+    type: input.type,
+    title: input.title,
+    body: input.body ?? '',
+    rating: input.rating ?? null,
+    screen: input.screen ?? null,
+    appVersion: input.appVersion ?? null,
+    platform: input.platform ?? null,
+    status: 'new',
+    adminNotes: null,
+    createdAt: now,
+    updatedAt: now,
+  };
+  await getContainer().items.create(doc);
+  return doc;
+}
+
+export async function getFeedback(id: string, productId: string): Promise<FeedbackDoc | null> {
+  try {
+    const { resource } = await getContainer().item(id, productId).read<FeedbackDoc>();
+    return resource ?? null;
+  } catch {
+    return null;
+  }
+}
+
+export async function listFeedback(
+  productId: string,
+  query: QueryFeedbackInput
+): Promise<FeedbackDoc[]> {
+  const conditions = ['c.productId = @pid'];
+  const params: { name: string; value: string | number }[] = [{ name: '@pid', value: productId }];
+
+  if (query.type) {
+    conditions.push('c.type = @type');
+    params.push({ name: '@type', value: query.type });
+  }
+  if (query.status) {
+    conditions.push('c.status = @status');
+    params.push({ name: '@status', value: query.status });
+  }
+
+  const sql = `SELECT * FROM c WHERE ${conditions.join(' AND ')} ORDER BY c.createdAt DESC OFFSET @offset LIMIT @limit`;
+  params.push({ name: '@offset', value: query.offset ?? 0 });
+  params.push({ name: '@limit', value: query.limit ?? 50 });
+
+  const { resources } = await getContainer()
+    .items.query<FeedbackDoc>({ query: sql, parameters: params })
+    .fetchAll();
+  return resources;
+}
+
+export async function updateFeedback(
+  id: string,
+  productId: string,
+  updates: UpdateFeedbackInput
+): Promise<FeedbackDoc | null> {
+  const existing = await getFeedback(id, productId);
+  if (!existing) return null;
+
+  const updated: FeedbackDoc = {
+    ...existing,
+    ...updates,
+    updatedAt: new Date().toISOString(),
+  };
+  await getContainer().item(id, productId).replace(updated);
+  return updated;
+}
+
+export async function deleteFeedback(id: string, productId: string): Promise<boolean> {
+  try {
+    await getContainer().item(id, productId).delete();
+    return true;
+  } catch {
+    return false;
+  }
+}
+
+export async function getFeedbackStats(productId: string): Promise<Record<string, number>> {
+  const { resources } = await getContainer()
+    .items.query<{ type: string; cnt: number }>({
+      query: 'SELECT c.type, COUNT(1) AS cnt FROM c WHERE c.productId = @pid GROUP BY c.type',
+      parameters: [{ name: '@pid', value: productId }],
+    })
+    .fetchAll();
+
+  const stats: Record<string, number> = { bug: 0, feature: 0, praise: 0, other: 0, total: 0 };
+  for (const r of resources) {
+    stats[r.type] = r.cnt;
+    stats.total += r.cnt;
+  }
+  return stats;
+}
diff --git a/services/platform-service/src/modules/feedback/routes.ts b/services/platform-service/src/modules/feedback/routes.ts
new file mode 100644
index 00000000..3e41856f
--- /dev/null
+++ b/services/platform-service/src/modules/feedback/routes.ts
@@ -0,0 +1,82 @@
+/**
+ * In-App Feedback routes.
+ * Authenticated: submit feedback. Admin: list, triage, delete.
+ */
+
+import type { FastifyInstance } from 'fastify';
+import { UnauthorizedError, ForbiddenError, NotFoundError } from '../../lib/errors.js';
+import { getRequestProductId } from '../../lib/request-context.js';
+import { CreateFeedbackSchema, UpdateFeedbackSchema, QueryFeedbackSchema } from './types.js';
+import {
+  createFeedback,
+  getFeedback,
+  listFeedback,
+  updateFeedback,
+  deleteFeedback,
+  getFeedbackStats,
+} from './repository.js';
+
+function requireAuth(req: { jwtPayload?: { sub: string; role?: string } }): string {
+  if (!req.jwtPayload?.sub) throw new UnauthorizedError('Authentication required');
+  return req.jwtPayload.sub;
+}
+
+function requireAdmin(req: { jwtPayload?: { sub: string; role?: string } }): void {
+  requireAuth(req);
+  if (req.jwtPayload?.role !== 'admin') throw new ForbiddenError('Admin access required');
+}
+
+export async function feedbackRoutes(app: FastifyInstance): Promise<void> {
+  // ── User: Submit feedback ─────────────────────────────────
+  app.post('/feedback', async (req, reply) => {
+    const userId = requireAuth(req);
+    const productId = getRequestProductId(req);
+    const input = CreateFeedbackSchema.parse(req.body);
+    const fb = await createFeedback(productId, userId, input);
+    reply.status(201);
+    return fb;
+  });
+
+  // ── Admin: List feedback ──────────────────────────────────
+  app.get('/feedback', async req => {
+    requireAdmin(req);
+    const productId = getRequestProductId(req);
+    const query = QueryFeedbackSchema.parse(req.query);
+    return listFeedback(productId, query);
+  });
+
+  // ── Admin: Get single feedback ────────────────────────────
+  app.get<{ Params: { id: string } }>('/feedback/:id', async req => {
+    requireAdmin(req);
+    const productId = getRequestProductId(req);
+    const fb = await getFeedback(req.params.id, productId);
+    if (!fb) throw new NotFoundError('Feedback not found');
+    return fb;
+  });
+
+  // ── Admin: Update feedback (triage) ───────────────────────
+  app.put<{ Params: { id: string } }>('/feedback/:id', async req => {
+    requireAdmin(req);
+    const productId = getRequestProductId(req);
+    const updates = UpdateFeedbackSchema.parse(req.body);
+    const fb = await updateFeedback(req.params.id, productId, updates);
+    if (!fb) throw new NotFoundError('Feedback not found');
+    return fb;
+  });
+
+  // ── Admin: Delete feedback ────────────────────────────────
+  app.delete<{ Params: { id: string } }>('/feedback/:id', async (req, reply) => {
+    requireAdmin(req);
+    const productId = getRequestProductId(req);
+    const ok = await deleteFeedback(req.params.id, productId);
+    if (!ok) throw new NotFoundError('Feedback not found');
+    reply.status(204);
+  });
+
+  // ── Admin: Feedback stats ─────────────────────────────────
+  app.get('/feedback/stats', async req => {
+    requireAdmin(req);
+    const productId = getRequestProductId(req);
+    return getFeedbackStats(productId);
+  });
+}
diff --git a/services/platform-service/src/modules/feedback/types.ts b/services/platform-service/src/modules/feedback/types.ts
new file mode 100644
index 00000000..cf993f0f
--- /dev/null
+++ b/services/platform-service/src/modules/feedback/types.ts
@@ -0,0 +1,54 @@
+/**
+ * In-App Feedback module — types and schemas.
+ * Users submit feedback (bug, feature, praise); admins triage.
+ */
+
+import { z } from 'zod';
+
+export type FeedbackType = 'bug' | 'feature' | 'praise' | 'other';
+export type FeedbackStatus = 'new' | 'reviewed' | 'planned' | 'resolved' | 'wont_fix';
+
+export interface FeedbackDoc {
+  id: string;
+  productId: string;
+  userId: string;
+  type: FeedbackType;
+  title: string;
+  body: string;
+  rating: number | null; // 1–5 optional satisfaction rating
+  screen: string | null; // which screen/page the feedback came from
+  appVersion: string | null;
+  platform: string | null; // web, ios, android
+  status: FeedbackStatus;
+  adminNotes: string | null;
+  createdAt: string;
+  updatedAt: string;
+}
+
+// ── Schemas ────────────────────────────────────────────────────
+
+export const CreateFeedbackSchema = z.object({
+  type: z.enum(['bug', 'feature', 'praise', 'other']),
+  title: z.string().min(1).max(200),
+  body: z.string().max(5000).default(''),
+  rating: z.number().int().min(1).max(5).nullable().default(null),
+  screen: z.string().max(100).nullable().default(null),
+  appVersion: z.string().max(50).nullable().default(null),
+  platform: z.string().max(20).nullable().default(null),
+});
+
+export const UpdateFeedbackSchema = z.object({
+  status: z.enum(['new', 'reviewed', 'planned', 'resolved', 'wont_fix']).optional(),
+  adminNotes: z.string().max(2000).nullable().optional(),
+});
+
+export const QueryFeedbackSchema = z.object({
+  type: z.enum(['bug', 'feature', 'praise', 'other']).optional(),
+  status: z.enum(['new', 'reviewed', 'planned', 'resolved', 'wont_fix']).optional(),
+  limit: z.coerce.number().int().min(1).max(100).default(50),
+  offset: z.coerce.number().int().min(0).default(0),
+});
+
+export type CreateFeedbackInput = z.infer<typeof CreateFeedbackSchema>;
+export type UpdateFeedbackInput = z.infer<typeof UpdateFeedbackSchema>;
+export type QueryFeedbackInput = z.infer<typeof QueryFeedbackSchema>;
diff --git a/services/platform-service/src/modules/impersonation/impersonation.test.ts b/services/platform-service/src/modules/impersonation/impersonation.test.ts
new file mode 100644
index 00000000..0d8a0e2e
--- /dev/null
+++ b/services/platform-service/src/modules/impersonation/impersonation.test.ts
@@ -0,0 +1,42 @@
+/**
+ * User Impersonation module — unit tests.
+ */
+
+import { describe, it, expect } from 'vitest';
+import { StartImpersonationSchema, StopImpersonationSchema } from './types.js';
+
+describe('StartImpersonationSchema', () => {
+  it('accepts valid input', () => {
+    const result = StartImpersonationSchema.parse({
+      targetUserId: 'user-123',
+      reason: 'Debugging timer sync issue',
+    });
+    expect(result.targetUserId).toBe('user-123');
+    expect(result.reason).toBe('Debugging timer sync issue');
+  });
+
+  it('rejects empty targetUserId', () => {
+    expect(() => StartImpersonationSchema.parse({ targetUserId: '', reason: 'test' })).toThrow();
+  });
+
+  it('rejects empty reason', () => {
+    expect(() => StartImpersonationSchema.parse({ targetUserId: 'u1', reason: '' })).toThrow();
+  });
+
+  it('rejects reason over 500 chars', () => {
+    expect(() =>
+      StartImpersonationSchema.parse({ targetUserId: 'u1', reason: 'x'.repeat(501) })
+    ).toThrow();
+  });
+});
+
+describe('StopImpersonationSchema', () => {
+  it('accepts valid sessionId', () => {
+    const result = StopImpersonationSchema.parse({ sessionId: 'imp-abc123' });
+    expect(result.sessionId).toBe('imp-abc123');
+  });
+
+  it('rejects empty sessionId', () => {
+    expect(() => StopImpersonationSchema.parse({ sessionId: '' })).toThrow();
+  });
+});
diff --git a/services/platform-service/src/modules/impersonation/repository.ts b/services/platform-service/src/modules/impersonation/repository.ts
new file mode 100644
index 00000000..3a876b8d
--- /dev/null
+++ b/services/platform-service/src/modules/impersonation/repository.ts
@@ -0,0 +1,82 @@
+/**
+ * User Impersonation repository — Cosmos DB CRUD.
+ */
+
+import { getRegisteredContainer } from '@bytelyst/cosmos';
+import type { ImpersonationSessionDoc, StartImpersonationInput } from './types.js';
+
+function getContainer() {
+  return getRegisteredContainer('impersonation_sessions');
+}
+
+export async function startImpersonation(
+  productId: string,
+  adminUserId: string,
+  input: StartImpersonationInput
+): Promise<ImpersonationSessionDoc> {
+  const now = new Date().toISOString();
+  const doc: ImpersonationSessionDoc = {
+    id: `imp-${Date.now()}-${Math.random().toString(36).slice(2, 8)}`,
+    productId,
+    adminUserId,
+    targetUserId: input.targetUserId,
+    reason: input.reason,
+    active: true,
+    startedAt: now,
+    endedAt: null,
+    createdAt: now,
+  };
+  await getContainer().items.create(doc);
+  return doc;
+}
+
+export async function stopImpersonation(
+  sessionId: string,
+  productId: string
+): Promise<ImpersonationSessionDoc | null> {
+  try {
+    const { resource } = await getContainer()
+      .item(sessionId, productId)
+      .read<ImpersonationSessionDoc>();
+    if (!resource || !resource.active) return null;
+    const updated = { ...resource, active: false, endedAt: new Date().toISOString() };
+    await getContainer().item(sessionId, productId).replace(updated);
+    return updated;
+  } catch {
+    return null;
+  }
+}
+
+export async function getActiveSession(
+  productId: string,
+  adminUserId: string
+): Promise<ImpersonationSessionDoc | null> {
+  const { resources } = await getContainer()
+    .items.query<ImpersonationSessionDoc>({
+      query:
+        'SELECT * FROM c WHERE c.productId = @pid AND c.adminUserId = @aid AND c.active = true',
+      parameters: [
+        { name: '@pid', value: productId },
+        { name: '@aid', value: adminUserId },
+      ],
+    })
+    .fetchAll();
+  return resources[0] ?? null;
+}
+
+export async function listSessions(
+  productId: string,
+  limit: number = 50
+): Promise<ImpersonationSessionDoc[]> {
+  const { resources } = await getContainer()
+    .items.query<ImpersonationSessionDoc>({
+      query:
+        'SELECT * FROM c WHERE c.productId = @pid ORDER BY c.createdAt DESC OFFSET 0 LIMIT @limit',
+      parameters: [
+        { name: '@pid', value: productId },
+        { name: '@limit', value: limit },
+      ],
+    })
+    .fetchAll();
+  return resources;
+}
diff --git a/services/platform-service/src/modules/impersonation/routes.ts b/services/platform-service/src/modules/impersonation/routes.ts
new file mode 100644
index 00000000..9d7aaaaf
--- /dev/null
+++ b/services/platform-service/src/modules/impersonation/routes.ts
@@ -0,0 +1,79 @@
+/**
+ * User Impersonation routes.
+ * Admin-only: start/stop impersonation, list sessions.
+ */
+
+import type { FastifyInstance } from 'fastify';
+import {
+  UnauthorizedError,
+  ForbiddenError,
+  NotFoundError,
+  BadRequestError,
+} from '../../lib/errors.js';
+import { getRequestProductId } from '../../lib/request-context.js';
+import { StartImpersonationSchema, StopImpersonationSchema } from './types.js';
+import {
+  startImpersonation,
+  stopImpersonation,
+  getActiveSession,
+  listSessions,
+} from './repository.js';
+
+function requireAdmin(req: { jwtPayload?: { sub: string; role?: string } }): string {
+  if (!req.jwtPayload?.sub) throw new UnauthorizedError('Authentication required');
+  if (req.jwtPayload.role !== 'admin') throw new ForbiddenError('Admin access required');
+  return req.jwtPayload.sub;
+}
+
+export async function impersonationRoutes(app: FastifyInstance): Promise<void> {
+  // ── Start impersonation ───────────────────────────────────
+  app.post('/impersonation/start', async (req, reply) => {
+    const adminUserId = requireAdmin(req);
+    const productId = getRequestProductId(req);
+    const input = StartImpersonationSchema.parse(req.body);
+
+    if (input.targetUserId === adminUserId) {
+      throw new BadRequestError('Cannot impersonate yourself');
+    }
+
+    // Check for existing active session
+    const existing = await getActiveSession(productId, adminUserId);
+    if (existing) {
+      throw new BadRequestError('Already impersonating a user. Stop current session first.');
+    }
+
+    const session = await startImpersonation(productId, adminUserId, input);
+    req.log.info(
+      { adminUserId, targetUserId: input.targetUserId, sessionId: session.id },
+      'impersonation started'
+    );
+    reply.status(201);
+    return session;
+  });
+
+  // ── Stop impersonation ────────────────────────────────────
+  app.post('/impersonation/stop', async req => {
+    const adminUserId = requireAdmin(req);
+    const productId = getRequestProductId(req);
+    const { sessionId } = StopImpersonationSchema.parse(req.body);
+    const session = await stopImpersonation(sessionId, productId);
+    if (!session) throw new NotFoundError('Session not found or already ended');
+    req.log.info({ adminUserId, sessionId }, 'impersonation stopped');
+    return session;
+  });
+
+  // ── Get my active session ─────────────────────────────────
+  app.get('/impersonation/active', async req => {
+    const adminUserId = requireAdmin(req);
+    const productId = getRequestProductId(req);
+    const session = await getActiveSession(productId, adminUserId);
+    return { session };
+  });
+
+  // ── List all sessions (audit trail) ───────────────────────
+  app.get('/impersonation/sessions', async req => {
+    requireAdmin(req);
+    const productId = getRequestProductId(req);
+    return listSessions(productId);
+  });
+}
diff --git a/services/platform-service/src/modules/impersonation/types.ts b/services/platform-service/src/modules/impersonation/types.ts
new file mode 100644
index 00000000..2d36a4f3
--- /dev/null
+++ b/services/platform-service/src/modules/impersonation/types.ts
@@ -0,0 +1,32 @@
+/**
+ * User Impersonation module — types and schemas.
+ * Admin-only: temporarily act as another user for debugging.
+ * All impersonation sessions are audit-logged.
+ */
+
+import { z } from 'zod';
+
+export interface ImpersonationSessionDoc {
+  id: string;
+  productId: string;
+  adminUserId: string; // the admin performing impersonation
+  targetUserId: string; // the user being impersonated
+  reason: string;
+  active: boolean;
+  startedAt: string;
+  endedAt: string | null;
+  createdAt: string;
+}
+
+// ── Schemas ────────────────────────────────────────────────────
+
+export const StartImpersonationSchema = z.object({
+  targetUserId: z.string().min(1),
+  reason: z.string().min(1).max(500),
+});
+
+export const StopImpersonationSchema = z.object({
+  sessionId: z.string().min(1),
+});
+
+export type StartImpersonationInput = z.infer<typeof StartImpersonationSchema>;
diff --git a/services/platform-service/src/server.ts b/services/platform-service/src/server.ts
index 1d10b97f..07e39cd5 100644
--- a/services/platform-service/src/server.ts
+++ b/services/platform-service/src/server.ts
@@ -64,6 +64,11 @@ import { sessionRoutes } from './modules/sessions/routes.js';
 import { maintenanceRoutes } from './modules/maintenance/routes.js';
 import { exportRoutes } from './modules/exports/routes.js';
 import { ipRuleRoutes } from './modules/ip-rules/routes.js';
+import { experimentRoutes } from './modules/experiments/routes.js';
+import { analyticsRoutes } from './modules/analytics/routes.js';
+import { feedbackRoutes } from './modules/feedback/routes.js';
+import { impersonationRoutes } from './modules/impersonation/routes.js';
+import { changelogRoutes } from './modules/changelog/routes.js';
 import { initCosmosIfNeeded } from './lib/cosmos-init.js';
 import { config } from './lib/config.js';
 
@@ -165,5 +170,11 @@ await app.register(maintenanceRoutes, { prefix: '/api' });
 await app.register(exportRoutes, { prefix: '/api' });
 // IP allow/deny rules
 await app.register(ipRuleRoutes, { prefix: '/api' });
+// P2 — Product Intelligence
+await app.register(experimentRoutes, { prefix: '/api' });
+await app.register(analyticsRoutes, { prefix: '/api' });
+await app.register(feedbackRoutes, { prefix: '/api' });
+await app.register(impersonationRoutes, { prefix: '/api' });
+await app.register(changelogRoutes, { prefix: '/api' });
 
 await startService(app, { port: config.PORT, host: config.HOST });