diff --git a/services/platform-service/src/modules/diagnostics/diagnostics.test.ts b/services/platform-service/src/modules/diagnostics/diagnostics.test.ts
index cb1d82ea..f9abfdff 100644
--- a/services/platform-service/src/modules/diagnostics/diagnostics.test.ts
+++ b/services/platform-service/src/modules/diagnostics/diagnostics.test.ts
@@ -4,10 +4,11 @@
  * @module diagnostics
  */
 
-import { describe, it, expect, beforeEach } from 'vitest';
+import { describe, it, expect } from 'vitest';
 import { randomUUID } from 'node:crypto';
 import * as repo from './repository.js';
 import {
+  generateId,
   CreateDebugSessionSchema,
   UpdateDebugSessionSchema,
   IngestTracesSchema,
@@ -21,10 +22,8 @@ import {
   type IngestLogsInput,
 } from './types.js';
 
-// Test helpers
-function generateId(prefix: string): string {
-  return `${prefix}_${randomUUID().replace(/-/g, '')}`;
-}
+// Test helpers - generateId is now imported from types.ts for DRY compliance
+// function generateId(prefix: string): string { ... } // REMOVED - using shared version
 
 function createTestSession(productId: string, overrides?: Partial<DebugSessionDoc>): DebugSessionDoc {
   const now = new Date().toISOString();
diff --git a/services/platform-service/src/modules/diagnostics/routes.ts b/services/platform-service/src/modules/diagnostics/routes.ts
index c775f447..65ac7f93 100644
--- a/services/platform-service/src/modules/diagnostics/routes.ts
+++ b/services/platform-service/src/modules/diagnostics/routes.ts
@@ -18,7 +18,7 @@
  */
 
 import type { FastifyInstance } from 'fastify';
-import { randomUUID } from 'node:crypto';
+import { generateId, buildPk } from './types.js';
 import { getRequestProductId } from '../../lib/request-context.js';
 import { requireRole } from '../../lib/auth.js';
 import { BadRequestError, NotFoundError } from '../../lib/errors.js';
@@ -49,15 +49,11 @@ import {
 // TODO-1: Event bus integration - need to emit events for session lifecycle
 // Import event bus once available: import { emitEvent } from '../../lib/event-bus.js';
 
+// Re-export shared helpers from types
+export { generateId, buildPk } from './types.js';
+
 // ─── Helpers ───────────────────────────────────────────────────────────────
 
-function generateId(prefix: string): string {
-  return `${prefix}_${randomUUID().replace(/-/g, '')}`;
-}
-
-function buildPk(productId: string, sessionId: string): string {
-  return `${productId}:${sessionId}`;
-}
 
 // TODO-2: PII Redaction - need to implement PII scanning for log messages
 // This should be shared with telemetry module
diff --git a/services/platform-service/src/modules/diagnostics/types.ts b/services/platform-service/src/modules/diagnostics/types.ts
index c00c431b..2242121a 100644
--- a/services/platform-service/src/modules/diagnostics/types.ts
+++ b/services/platform-service/src/modules/diagnostics/types.ts
@@ -12,6 +12,24 @@
 
 import { z } from 'zod';
 
+import { randomUUID } from 'node:crypto';
+
+/**
+ * Generate a prefixed ID for diagnostics documents.
+ * Exported for use in routes and tests.
+ */
+export function generateId(prefix: string): string {
+  return `${prefix}_${randomUUID().replace(/-/g, '')}`;
+}
+
+/**
+ * Build composite partition key for traces/logs.
+ * Exported for use in routes.
+ */
+export function buildPk(productId: string, sessionId: string): string {
+  return `${productId}:${sessionId}`;
+}
+
 // ─────────────────────────────────────────────────────────────────────────────
 // Enums
 // ─────────────────────────────────────────────────────────────────────────────