fix(platform-service): 5 bugs in recent P2/P3 implementations

- diagnostics/subscribers: use correct template IDs
  'diagnostics-session-cancelled' and 'diagnostics-session-completed'
  instead of non-existent 'generic' (would throw at runtime)
- delivery/templates: add missing 'broadcast' email template used by
  broadcast delivery route (dispatchEmail would throw on unknown ID)
- broadcasts/routes: replace broken dot-path 'metrics.sent' update
  with proper updateBroadcastMetrics() call, add productName variable
- exports/routes: store serialized data on job doc, add download
  endpoint GET /exports/:id/download with content-type headers,
  exclude data payload from metadata GET endpoint
- waitlist/routes: store invitation doc ID (inv_...) instead of
  code string (WL-...) in invitationCodeId field
- delivery/delivery.test.ts: update template count 12 -> 13
- Typecheck clean, 1483/1483 tests pass

services/platform-service/src/modules/broadcasts/routes.ts

@@ -225,6 +225,7 @@ async function adminRoutes(app: FastifyInstance): Promise<void> {
                   displayName: user.displayName,
                   subject: broadcast.title,
                   body: broadcast.body ?? '',
+                  productName: productId,
                 },
                 productId,
                 userId: user.id,
@@ -242,9 +243,11 @@ async function adminRoutes(app: FastifyInstance): Promise<void> {
 
         await repo.updateBroadcast(id, productId, {
           status: BroadcastStatus.SENT,
-          'metrics.sent': sent,
-          'metrics.targetCount': recipients.length,
-        } as Record<string, unknown>);
+        });
+        await repo.updateBroadcastMetrics(id, productId, {
+          sentCount: sent,
+          targetedCount: recipients.length,
+        });
         log.info(
           { broadcastId: id, sent, total: recipients.length },
           '[broadcasts] Delivery complete'

services/platform-service/src/modules/delivery/delivery.test.ts

@@ -123,8 +123,8 @@ describe('SendSlackSchema', () => {
 // ── Template Tests ───────────────────────────────────────────
 
 describe('templates', () => {
-  it('should have 12 built-in templates', () => {
-    expect(BUILT_IN_TEMPLATES.length).toBe(12);
+  it('should have 13 built-in templates', () => {
+    expect(BUILT_IN_TEMPLATES.length).toBe(13);
   });
 
   it('should find template by ID', () => {

services/platform-service/src/modules/delivery/templates.ts

@@ -122,6 +122,19 @@ export const BUILT_IN_TEMPLATES: EmailTemplate[] = [
     bodyText: `License expires in {{daysLeft}} days.\n\nRenew: {{renewUrl}}\n\n— The {{productName}} Team`,
     variables: ['displayName', 'productName', 'daysLeft', 'renewUrl'],
   },
+  // ── Broadcast Template ──────────────────────────────────────────
+  {
+    id: 'broadcast',
+    name: 'Broadcast Message',
+    subject: '{{subject}}',
+    bodyHtml: `
+      <p>Hi {{displayName}},</p>
+      {{body}}
+      <p>— The {{productName}} Team</p>
+    `.trim(),
+    bodyText: `Hi {{displayName}},\n\n{{body}}\n\n— The {{productName}} Team`,
+    variables: ['displayName', 'subject', 'body', 'productName'],
+  },
   // ── Diagnostics Templates ─────────────────────────────────────
   {
     id: 'diagnostics-session-created',

services/platform-service/src/modules/diagnostics/subscribers.ts

@@ -132,11 +132,14 @@ export function registerDiagnosticsSubscribers(
             await dispatchEmail(
               {
                 to: admin.email,
-                templateId: 'generic',
+                templateId: 'diagnostics-session-cancelled',
                 variables: {
-                  displayName: admin.displayName,
-                  subject: 'Debug session cancelled',
-                  body: `Your debug session (${event.payload.sessionId}) was cancelled${event.payload.reason ? `: ${event.payload.reason}` : '.'}.`,
+                  productName: event.payload.productId,
+                  sessionId: event.payload.sessionId,
+                  targetUserId: session.targetUserId ?? 'unknown',
+                  cancelledBy: event.payload.cancelledBy,
+                  reason: event.payload.reason ?? 'No reason provided',
+                  cancelledAt: new Date().toISOString(),
                 },
                 productId: event.payload.productId,
                 userId: session.createdBy,
@@ -185,21 +188,24 @@ export function registerDiagnosticsSubscribers(
           const admin = await getUserById(session.createdBy);
           if (admin) {
             const stats = event.payload.stats;
-            const summary = [
-              `Debug session ${event.payload.sessionId} completed.`,
-              `Logs collected: ${stats.logCount}`,
-              `Traces collected: ${stats.traceCount}`,
-              `Screenshots captured: ${stats.screenshotCount}`,
-              `Ended at: ${event.payload.endedAt}`,
-            ].join('\n');
+            const startedAt = session.startedAt ?? session.createdAt;
+            const endedAt = event.payload.endedAt;
+            const durationMs =
+              startedAt && endedAt
+                ? new Date(endedAt).getTime() - new Date(startedAt).getTime()
+                : 0;
+            const durationMinutes = String(Math.round(durationMs / 60_000));
             await dispatchEmail(
               {
                 to: admin.email,
-                templateId: 'generic',
+                templateId: 'diagnostics-session-completed',
                 variables: {
-                  displayName: admin.displayName,
-                  subject: 'Debug session completed — summary',
-                  body: summary,
+                  productName: event.payload.productId,
+                  sessionId: event.payload.sessionId,
+                  durationMinutes,
+                  logCount: String(stats.logCount),
+                  traceCount: String(stats.traceCount),
+                  screenshotCount: String(stats.screenshotCount),
                 },
                 productId: event.payload.productId,
                 userId: session.createdBy,

services/platform-service/src/modules/exports/routes.ts

@@ -75,6 +75,7 @@ export async function exportRoutes(app: FastifyInstance) {
         await repo.updateExportJob({
           ...created,
           status: 'ready',
+          data: serialized,
           rowCount: rows.length,
           fileSizeBytes: Buffer.byteLength(serialized, 'utf8'),
           fileName,
@@ -106,13 +107,31 @@ export async function exportRoutes(app: FastifyInstance) {
     return { exports: jobs, count: jobs.length };
   });
 
-  // Get a specific export job
+  // Get a specific export job (metadata only, no data payload)
   app.get('/exports/:id', async req => {
     const access = await requireExportRead(req);
     const { id } = req.params as { id: string };
     const job = await repo.getExportJob(id, access.productId);
     if (!job) throw new BadRequestError('Export job not found');
-    return job;
+    const meta = { ...job };
+    delete meta.data;
+    return meta;
+  });
+
+  // Download export data
+  app.get('/exports/:id/download', async (req, reply) => {
+    const access = await requireExportRead(req);
+    const { id } = req.params as { id: string };
+    const job = await repo.getExportJob(id, access.productId);
+    if (!job) throw new BadRequestError('Export job not found');
+    if (job.status !== 'ready' || !job.data) {
+      throw new BadRequestError('Export is not ready for download');
+    }
+    const contentType = job.format === 'json' ? 'application/json' : 'text/csv';
+    return reply
+      .header('Content-Type', contentType)
+      .header('Content-Disposition', `attachment; filename="${job.fileName || 'export'}"`)
+      .send(job.data);
   });
 }
 

services/platform-service/src/modules/exports/types.ts

@@ -15,6 +15,7 @@ export interface ExportJobDoc {
   status: ExportStatus;
   requestedBy: string;
   blobUrl?: string;
+  data?: string;
   fileName?: string;
   rowCount?: number;
   fileSizeBytes?: number;

services/platform-service/src/modules/waitlist/routes.ts

@@ -455,7 +455,7 @@ export async function waitlistRoutes(app: FastifyInstance) {
         await repo.update(entry.id, entry.email, {
           status: 'invited',
           invitedAt: now,
-          invitationCodeId: code,
+          invitationCodeId: invDoc.id,
         });
         invited++;
       } catch {