diff --git a/backend/src/lib/cosmos-init.ts b/backend/src/lib/cosmos-init.ts
index 0021e41..59486e5 100644
--- a/backend/src/lib/cosmos-init.ts
+++ b/backend/src/lib/cosmos-init.ts
@@ -1,5 +1,6 @@
 import { initializeAllContainers, registerContainers } from '@bytelyst/cosmos';
 import type { ContainerConfig } from '@bytelyst/cosmos';
+import type { Logger } from '@bytelyst/logger';
 import { config } from './config.js';
 
 const CONTAINER_DEFS: Record<string, ContainerConfig> = {
@@ -27,7 +28,9 @@ const CONTAINER_DEFS: Record<string, ContainerConfig> = {
   palace_diaries: { partitionKeyPath: '/userId' },
 };
 
-export async function initCosmosIfNeeded(): Promise<void> {
+type CosmosInitLogger = Pick<Logger, 'error' | 'info'>;
+
+export async function initCosmosIfNeeded(logger?: CosmosInitLogger): Promise<void> {
   registerContainers(CONTAINER_DEFS);
 
   const shouldInit = config.NODE_ENV !== 'production' || process.env.COSMOS_AUTO_INIT === 'true';
@@ -37,9 +40,8 @@ export async function initCosmosIfNeeded(): Promise<void> {
 
   try {
     await initializeAllContainers();
-    process.stdout.write('[notelett-backend] Cosmos containers ensured\n');
+    logger?.info('Cosmos containers ensured');
   } catch (err) {
-    const msg = err instanceof Error ? err.message : String(err);
-    process.stderr.write(`[notelett-backend] Cosmos init failed: ${msg}\n`);
+    logger?.error('Cosmos init failed', err);
   }
 }
diff --git a/backend/src/modules/note-prompts/scheduler.ts b/backend/src/modules/note-prompts/scheduler.ts
index 157e323..70e39b9 100644
--- a/backend/src/modules/note-prompts/scheduler.ts
+++ b/backend/src/modules/note-prompts/scheduler.ts
@@ -22,6 +22,16 @@ import { stripHtmlForEmbedding } from '../../lib/embeddings.js';
 
 // ── Types ──────────────────────────────────────────────────────────
 
+type SchedulerLogger = {
+  error: (details: Record<string, unknown>, message: string) => void;
+};
+
+let schedulerLogger: SchedulerLogger = { error: () => undefined };
+
+export function setSchedulerLogger(logger: SchedulerLogger): void {
+  schedulerLogger = logger;
+}
+
 export interface PromptScheduleDoc {
   id: string;
   productId: string;
@@ -216,15 +226,17 @@ export async function runSchedulerTick(): Promise<number> {
       trackEvent('scheduled_action_fired', schedule.userId, { scheduleId: schedule.id, templateSlug: template?.slug ?? schedule.templateId });
       ran++;
     } catch (err: unknown) {
-      const msg = err instanceof Error ? err.message : 'Unknown scheduler error';
-      process.stderr.write(`[scheduler] Failed to run schedule ${schedule.id}: ${msg}\n`);
+      schedulerLogger.error({ err, scheduleId: schedule.id }, 'Failed to run scheduled prompt');
     }
   }
 
   return ran;
 }
 
-export function startSchedulerLoop(intervalMs = 60_000): void {
+export function startSchedulerLoop(intervalMs = 60_000, logger?: SchedulerLogger): void {
+  if (logger) {
+    setSchedulerLogger(logger);
+  }
   if (schedulerInterval) return;
   schedulerInterval = setInterval(() => {
     void runSchedulerTick();
diff --git a/backend/src/server.test.ts b/backend/src/server.test.ts
index eeed50f..a1fa761 100644
--- a/backend/src/server.test.ts
+++ b/backend/src/server.test.ts
@@ -6,12 +6,18 @@ const startServiceMock = vi.fn(async () => undefined);
 const initCosmosIfNeededMock = vi.fn(async () => undefined);
 const initDatastoreMock = vi.fn(() => undefined);
 const diagnosticsRoutesMock = vi.fn(async () => undefined);
+const startSchedulerLoopMock = vi.fn();
+const stopSchedulerLoopMock = vi.fn();
 
 const appMock = {
   register: vi.fn(async () => undefined),
   get: vi.fn(),
   post: vi.fn(),
   addHook: vi.fn(),
+  log: {
+    error: vi.fn(),
+    info: vi.fn(),
+  },
 };
 
 vi.mock('@bytelyst/fastify-core', () => ({
@@ -36,8 +42,8 @@ vi.mock('./modules/ecosystem-phase3/routes.js', () => ({ ecosystemPhase3Routes:
 vi.mock('./modules/note-prompts/routes.js', () => ({ notePromptRoutes: vi.fn() }));
 vi.mock('./modules/note-prompts/scheduler.js', () => ({
   promptSchedulerRoutes: vi.fn(),
-  startSchedulerLoop: vi.fn(),
-  stopSchedulerLoop: vi.fn(),
+  startSchedulerLoop: startSchedulerLoopMock,
+  stopSchedulerLoop: stopSchedulerLoopMock,
 }));
 vi.mock('./modules/intake/routes.js', () => ({ intakeRoutes: vi.fn() }));
 vi.mock('./modules/note-collaborators/routes.js', () => ({ noteCollaboratorRoutes: vi.fn() }));
@@ -51,6 +57,7 @@ vi.mock('./lib/config.js', () => ({
     PORT: 4016,
     HOST: '0.0.0.0',
     JWT_SECRET: 'test-secret',
+    NODE_ENV: 'test',
   },
 }));
 vi.mock('./lib/product-config.js', () => ({
@@ -78,12 +85,16 @@ describe('server bootstrap', () => {
   it('initializes app, routes, and starts service', async () => {
     await import('./server.js');
 
-    expect(initCosmosIfNeededMock).toHaveBeenCalledOnce();
+    expect(initCosmosIfNeededMock).toHaveBeenCalledWith(expect.objectContaining({
+      error: expect.any(Function),
+      info: expect.any(Function),
+    }));
     expect(initDatastoreMock).toHaveBeenCalledOnce();
     expect(createServiceAppMock).toHaveBeenCalledOnce();
     expect(registerOptionalJwtContextMock).toHaveBeenCalledOnce();
     expect(appMock.register).toHaveBeenCalledTimes(14);
     expect(diagnosticsRoutesMock).toHaveBeenCalledWith(appMock);
+    expect(startSchedulerLoopMock).toHaveBeenCalledWith(60_000, appMock.log);
     expect(startServiceMock).toHaveBeenCalledWith(appMock, { port: 4016, host: '0.0.0.0' });
   });
 });
diff --git a/backend/src/server.ts b/backend/src/server.ts
index 39c92b1..dc3458a 100644
--- a/backend/src/server.ts
+++ b/backend/src/server.ts
@@ -1,4 +1,5 @@
 import { createServiceApp, registerOptionalJwtContext, startService } from '@bytelyst/fastify-core';
+import { createLogger } from '@bytelyst/logger';
 import { jwtVerify } from 'jose';
 import { noteAgentActionRoutes } from './modules/note-agent-actions/routes.js';
 import { ecosystemPhase1Routes } from './modules/ecosystem-phase1/routes.js';
@@ -27,8 +28,12 @@ import { findShareByToken } from './modules/note-shares/repository.js';
 import * as noteRepo from './modules/notes/repository.js';
 
 const jwtSecret = new TextEncoder().encode(config.JWT_SECRET);
+const startupLogger = createLogger({
+  service: config.SERVICE_NAME,
+  isDev: config.NODE_ENV !== 'production',
+});
 
-await initCosmosIfNeeded();
+await initCosmosIfNeeded(startupLogger);
 initDatastore();
 
 const app = await createServiceApp({
@@ -74,7 +79,7 @@ await registerApiPlugin(noteCollaboratorRoutes);
 await registerApiPlugin(palaceRoutes);
 
 // ── Start scheduler loop (F25) ────────────────────────────────────
-startSchedulerLoop();
+startSchedulerLoop(60_000, app.log);
 initWebhookSubscriber();
 app.addHook('onClose', async () => { stopSchedulerLoop(); stopWebhookSubscriber(); });