From 7702f7e19a4898df6074d906583e600869c3f10b Mon Sep 17 00:00:00 2001
From: Lucas Berger <me@lucasberger.ca>
Date: Tue, 9 Jun 2026 22:22:04 -0400
Subject: [PATCH] fix(05-review): CR-01+WR-01 prune sentReminders after each
 scan and mark-sent after dispatch

---
 apps/api/src/broker/reminderScheduler.ts | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/apps/api/src/broker/reminderScheduler.ts b/apps/api/src/broker/reminderScheduler.ts
index 9eb531d..b8ace68 100644
--- a/apps/api/src/broker/reminderScheduler.ts
+++ b/apps/api/src/broker/reminderScheduler.ts
@@ -130,8 +130,6 @@ export async function runReminderCheck(now = new Date()): Promise<void> {
     try {
       const key = `${uid}:${minuteBucket}`
       if (sentReminders.has(key)) continue
-      // Mark sent BEFORE dispatching to prevent re-entry on concurrent ticks
-      sentReminders.add(key)
 
       const dateStr = yyyyMmDd(event.dtstartUtc)
       const notification: NotificationPayload = {
@@ -157,6 +155,11 @@ export async function runReminderCheck(now = new Date()): Promise<void> {
           )
         }
       }
+
+      // WR-01: mark sent AFTER all dispatches have been attempted. Pre-marking before
+      // dispatch prevents retry in the same bucket when dispatchPush throws — at-least-once
+      // delivery requires not pre-marking the key.
+      sentReminders.add(key)
     } catch (err) {
       // Per-event error isolation (T-05-18): one bad event never aborts remaining events.
       console.error(
@@ -165,6 +168,18 @@ export async function runReminderCheck(now = new Date()): Promise<void> {
       )
     }
   }
+
+  // CR-01: Prune stale entries from sentReminders to prevent unbounded growth.
+  // Entries for the previous minute bucket and older are no longer needed — the
+  // dedup window is (uid, minuteBucket), and the current minute has now been
+  // processed. Keep only the current bucket; discard everything older.
+  const staleBucket = minuteBucket - 1
+  for (const key of sentReminders) {
+    const colonIdx = key.lastIndexOf(':')
+    if (colonIdx !== -1 && Number(key.slice(colonIdx + 1)) < staleBucket) {
+      sentReminders.delete(key)
+    }
+  }
 }
 
 // ── Scheduler ─────────────────────────────────────────────────────────────────