fix digest job race: delete sent events by ID, not timestamp

Bug: runJob computed since = sub.last_digest_at, fetched events with
received_at > since, sent the digest (slow), then deleted ALL events
with received_at > since. Any /notify event that arrived between the
fetch and the delete was also received_at > since, so it was deleted
without ever being sent in a digest.

Two changes:

1. Delete by exact event IDs (src/database.ts, src/worker/email.ts):
   Added deleteEventsByIds(subscriptionId, eventIds) which deletes
   only the events that were actually fetched + sent. The old
   timestamp-based delete is retained but no longer called from runJob.

2. Re-fetch subscription on each cron tick (src/worker/email.ts):
   createJob's closure captured the original sub, so sub.last_digest_at
   stayed stale in memory. Every subsequent tick recomputed since from
   the old value, re-fetching and re-sending duplicate events. Now each
   tick re-fetches the subscription from the DB via getSubscriptionById
   before calling runJob.

Fixes bead mailship-091

src/database.ts

@@ -319,6 +319,18 @@ export const deleteEventsForSubscription = instrument(
   }
 )
 
+export const deleteEventsByIds = instrument(
+  'database.deleteEventsByIds',
+  async (subscriptionId: string, eventIds: string[]) => {
+    if (eventIds.length === 0) return
+    const placeholders = eventIds.map(() => '?').join(',')
+    await run(
+      `DELETE FROM events WHERE subscription_id = ? AND id IN (${placeholders})`,
+      [subscriptionId, ...eventIds]
+    )
+  }
+)
+
 export const purgeEventsOlderThan = instrument(
   'database.purgeEventsOlderThan',
   async (timestamp: number) => {

src/worker/email.ts

@@ -33,8 +33,11 @@ export const runJob = async (sub: Subscription) => {
     const digest = new Digest(sub)
     await digest.sendFromStoredEvents(events)
 
-    // Clean up processed events
-    await db.deleteEventsForSubscription(sub.id, since)
+    // Collect the exact IDs that were fetched + sent, then delete ONLY those.
+    // Deleting by timestamp (received_at > since) would also remove any event
+    // that arrived between the fetch and the delete — the race condition.
+    const sentIds = events.map(e => e.id)
+    await db.deleteEventsByIds(sub.id, sentIds)
     await db.updateLastDigestAt(sub.id, Math.floor(Date.now() / 1000))
 
     console.log('worker: job completed', sub.id, 'in', Date.now() - start, 'ms')
@@ -49,7 +52,12 @@ const createJob = (sub: Subscription) => {
   const cron = getCronExpression(sub.frequency)
 
   const run = async () => {
-    await runJob(sub)
+    // Re-fetch the subscription to pick up the latest last_digest_at.
+    // The closure-captured `sub` is stale — its last_digest_at never
+    // advances, so every tick would re-fetch and re-send old events.
+    const fresh = await db.getSubscriptionById(sub.id)
+    if (!fresh) return
+    await runJob(fresh)
   }
 
   return CronJob.from({

test/event-arrival-race.test.js

@@ -0,0 +1,139 @@
+#!/usr/bin/env node
+// Test: event-arrival race in digest job — fix verification
+//
+// The original bug: runJob fetched events via getEventsForSubscription(sub.id, since),
+// sent the digest (slow), then deleted events via deleteEventsForSubscription(sub.id, since)
+// which deletes EVERY row with received_at > since. Any event that arrived between
+// the fetch and the delete was also received_at > since, so it was deleted without
+// ever being emailed.
+//
+// The fix: deleteEventsByIds(sub.id, sentEventIds) deletes only the exact event IDs
+// that were fetched and sent. A late-arriving event (inserted after the fetch) has
+// a different ID and is not touched.
+//
+// This test simulates the sequence with the fixed approach:
+// 1. Create a confirmed subscription with a known last_digest_at
+// 2. Insert event A
+// 3. Fetch events for the subscription (simulating runJob's fetch)
+// 4. Insert event B after the fetch (simulating a /notify arriving during digest send)
+// 5. Delete ONLY the event A IDs (the fix — instead of timestamp-based delete)
+// 6. Verify event B survives (it arrived after fetch and was never sent)
+
+import * as db from '../dist/database.js'
+
+let passed = 0
+let failed = 0
+
+function assert(label, ok, detail) {
+  if (ok) {
+    console.log(`  ? ${label}`)
+    passed++
+  } else {
+    console.log(`  ? ${label} -- ${detail || ''}`)
+    failed++
+  }
+}
+
+function sleep(ms) {
+  return new Promise(resolve => setTimeout(resolve, ms))
+}
+
+async function main() {
+  await db.migrate()
+
+  const pubkey = 'race-test-' + Date.now()
+  const email = 'race-test-' + Date.now() + '@example.com'
+
+  // Step 1: Create and confirm subscription
+  console.log('1. Create confirmed subscription')
+  const sub = await db.insertSubscription(pubkey, email, 'daily')
+  assert('subscription created', !!sub, 'insert returned null')
+  if (!sub) { process.exit(1) }
+
+  const confirmed = await db.confirmSubscription(sub.key)
+  assert('subscription confirmed', !!confirmed, 'confirm returned null')
+  if (!confirmed) { process.exit(1) }
+
+  // Set last_digest_at to a known time well in the past.
+  // This is the "since" value runJob would use.
+  const since = Math.floor(Date.now() / 1000) - 60  // 60 seconds ago
+  await db.updateLastDigestAt(confirmed.id, since)
+
+  // Wait 1s so event received_at timestamps (whole seconds) are strictly > since.
+  await sleep(1100)
+
+  // Step 2: Insert Event A — simulates events that trigger a digest run
+  console.log('\n2. Insert Event A (triggers digest)')
+  const eventA_id = 'race-event-a-' + Date.now()
+  const eventA = {
+    id: eventA_id,
+    kind: 1,
+    pubkey: 'abc',
+    content: 'event A content',
+    created_at: Math.floor(Date.now() / 1000),
+    tags: []
+  }
+  const storedA = await db.insertEvent(eventA_id, confirmed.id, eventA, 'wss://relay.damus.io')
+  assert('Event A stored', storedA === true, `got ${storedA}`)
+
+  // Step 3: Fetch events — simulating what runJob does with since=last_digest_at
+  console.log('\n3. Fetch events for subscription (simulating runJob fetch)')
+  const fetched = await db.getEventsForSubscription(confirmed.id, since)
+  assert('Event A was fetched', fetched.some(e => e.id === eventA_id),
+    `fetched ids: [${fetched.map(e => e.id).join(', ')}]`)
+
+  // Step 4: Insert Event B after the fetch — simulating a /notify arriving
+  //         during the slow digest send (profile loads, MJML render, SMTP).
+  console.log('\n4. Insert Event B AFTER fetch (simulating event arriving during digest send)')
+  await sleep(100)  // ensure distinct received_at
+  const eventB_id = 'race-event-b-' + Date.now()
+  const eventB = {
+    id: eventB_id,
+    kind: 1,
+    pubkey: 'def',
+    content: 'event B content — arrived during send',
+    created_at: Math.floor(Date.now() / 1000),
+    tags: []
+  }
+  const storedB = await db.insertEvent(eventB_id, confirmed.id, eventB, 'wss://relay.damus.io')
+  assert('Event B stored', storedB === true, `got ${storedB}`)
+
+  // Step 5: Delete ONLY the exact event IDs that were fetched + sent — THE FIX.
+  //         Unlike the old timestamp-based delete, this does NOT touch Event B
+  //         because Event B has a different ID.
+  console.log('\n5. Delete events by exact IDs (the fix — deleteEventsByIds)')
+  const sentIds = fetched.map(e => e.id)
+  await db.deleteEventsByIds(confirmed.id, sentIds)
+  console.log('   deleted ids:', JSON.stringify(sentIds))
+
+  // Step 6: Check which events remain.
+  //         CORRECT BEHAVIOR: Only Event A (which was sent) is deleted.
+  //         Event B (which arrived after fetch) must survive.
+  console.log('\n6. Check remaining events after delete')
+  const remaining = await db.getEventsForSubscription(confirmed.id, since - 10)
+
+  const eventB_survived = remaining.some(e => e.id === eventB_id)
+  assert(
+    'Event B survives the delete (it arrived after fetch and was never sent)',
+    eventB_survived,
+    `Event B was deleted despite never being sent. ` +
+    `remaining events: [${remaining.map(e => e.id).join(', ')}]`
+  )
+
+  // Verify Event A is gone (it was sent, so deletion is correct for A)
+  const eventA_survived = remaining.some(e => e.id === eventA_id)
+  assert(
+    'Event A is deleted (it was fetched and sent)',
+    !eventA_survived,
+    `Event A should have been deleted but is still present`
+  )
+
+  console.log('')
+  console.log(`Results: ${passed} passed, ${failed} failed`)
+  process.exit(failed > 0 ? 1 : 0)
+}
+
+main().catch(err => {
+  console.error('Unhandled error in test:', err)
+  process.exit(1)
+})