Fix push notifications never delivered — 3 root causes

1. CRITICAL: Double idempotency check silently discarded every notification.
   process_scheduled_notifications called try_mark_notification_pushed first,
   then send_fcm called it again and saw "already pushed" → skipped FCM send.
   Fix: Remove the check from process_scheduled_notifications; send_fcm's
   own check is sufficient (and needed for direct Flutter client calls).

2. SEND_FCM_URL env var crash: If not configured, edge function crashed on
   module load. Fix: Derive from SUPABASE_URL (always auto-set) as fallback.

3. Timing windows too narrow: ±30s windows with 60s cron intervals could
   miss events between runs. Fix: Widen to ±90s. ON CONFLICT DO NOTHING
   prevents duplicates, making wider windows safe.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

supabase/functions/process_scheduled_notifications/index.ts

@@ -2,7 +2,8 @@ import { createClient } from 'npm:@supabase/supabase-js@2'
 
 // Minimal Deno Edge Function to process queued scheduled_notifications
 // Environment variables required:
-// SUPABASE_URL, SUPABASE_SERVICE_ROLE_KEY, SEND_FCM_URL
+// SUPABASE_URL, SUPABASE_SERVICE_ROLE_KEY
+// Optional: SEND_FCM_URL (defaults to ${SUPABASE_URL}/functions/v1/send_fcm)
 
 const corsHeaders = {
   'Access-Control-Allow-Origin': '*',
@@ -10,7 +11,8 @@ const corsHeaders = {
 }
 
 const supabase = createClient(Deno.env.get('SUPABASE_URL')!, Deno.env.get('SUPABASE_SERVICE_ROLE_KEY')!)
-const SEND_FCM_URL = Deno.env.get('SEND_FCM_URL')!
+const SEND_FCM_URL = Deno.env.get('SEND_FCM_URL')
+  || `${Deno.env.get('SUPABASE_URL')!}/functions/v1/send_fcm`
 const BATCH_SIZE = Number(Deno.env.get('PROCESSOR_BATCH_SIZE') || '50')
 
 // deterministic UUIDv5-like from a name using SHA-1
@@ -58,20 +60,9 @@ async function processBatch() {
       const idSource = `${scheduleId || ''}-${r.task_id || ''}-${r.it_service_request_id || ''}-${r.pass_slip_id || ''}-${userId}-${notifyType}-${r.epoch || 0}`
       const notificationId = await uuidFromName(idSource)
 
-      // Attempt to mark idempotent push
+      // Idempotency is handled by send_fcm via try_mark_notification_pushed.
-      const { data: markData, error: markErr } = await supabase.rpc('try_mark_notification_pushed', { p_notification_id: notificationId })
+      // Do NOT call it here — doing so would mark the notification as pushed
-      if (markErr) {
+      // before send_fcm sees it, causing send_fcm to skip the actual FCM send.
-        console.warn('try_mark_notification_pushed error', markErr)
-        // do not mark processed; increment retry
-        await supabase.from('scheduled_notifications').update({ retry_count: r.retry_count + 1, last_error: String(markErr) }).eq('id', rowId)
-        continue
-      }
-
-      if (markData === false) {
-        console.log('Notification already pushed, skipping', notificationId)
-        await supabase.from('scheduled_notifications').update({ processed: true, processed_at: new Date().toISOString() }).eq('id', rowId)
-        continue
-      }
 
       // Prepare message based on notify_type
       let title = ''

supabase/migrations/20260321_extend_scheduled_notifications.sql

@@ -71,8 +71,8 @@ BEGIN
   FOR rec IN
     SELECT id AS schedule_id, user_id, start_time AS start_at
     FROM public.duty_schedules
-    WHERE start_time BETWEEN now() + interval '15 minutes' - interval '30 seconds'
+    WHERE start_time BETWEEN now() + interval '15 minutes' - interval '90 seconds'
-                         AND now() + interval '15 minutes' + interval '30 seconds'
+                         AND now() + interval '15 minutes' + interval '90 seconds'
       AND status = 'active'
   LOOP
     -- Skip if user already checked in for this duty
@@ -92,7 +92,7 @@ BEGIN
   FOR rec IN
     SELECT id AS schedule_id, user_id, end_time AS end_at
     FROM public.duty_schedules
-    WHERE end_time BETWEEN now() - interval '30 seconds' AND now() + interval '30 seconds'
+    WHERE end_time BETWEEN now() - interval '90 seconds' AND now() + interval '90 seconds'
       AND status IN ('arrival', 'late')
   LOOP
     INSERT INTO public.scheduled_notifications (schedule_id, user_id, notify_type, scheduled_for)
@@ -235,8 +235,8 @@ BEGIN
     JOIN public.it_service_request_assignments isra ON isra.request_id = isr.id
     WHERE isr.status IN ('scheduled', 'in_progress_dry_run')
       AND isr.event_date IS NOT NULL
-      AND isr.event_date BETWEEN now() + interval '60 minutes' - interval '30 seconds'
+      AND isr.event_date BETWEEN now() + interval '60 minutes' - interval '90 seconds'
-                              AND now() + interval '60 minutes' + interval '30 seconds'
+                              AND now() + interval '60 minutes' + interval '90 seconds'
   LOOP
     INSERT INTO public.scheduled_notifications
       (it_service_request_id, user_id, notify_type, scheduled_for)
@@ -348,8 +348,8 @@ BEGIN
   FOR rec IN
     SELECT ds.id AS schedule_id, ds.user_id, ds.end_time
     FROM public.duty_schedules ds
-    WHERE ds.end_time BETWEEN now() + interval '15 minutes' - interval '30 seconds'
+    WHERE ds.end_time BETWEEN now() + interval '15 minutes' - interval '90 seconds'
-                          AND now() + interval '15 minutes' + interval '30 seconds'
+                          AND now() + interval '15 minutes' + interval '90 seconds'
       AND ds.status IN ('arrival', 'late')
       -- User has pending (non-paused) tasks
       AND EXISTS (
@@ -395,7 +395,7 @@ BEGIN
     AND ps.slip_end IS NULL
     AND ps.slip_start IS NOT NULL
     AND ps.slip_start + interval '45 minutes'
-        BETWEEN now() - interval '30 seconds' AND now() + interval '30 seconds'
+        BETWEEN now() - interval '90 seconds' AND now() + interval '90 seconds'
   ON CONFLICT DO NOTHING;
 END;
 $$;