fix(aggregator): sanitize stored quiet prefs on read

pm-stack/aggregator/src/alerts.ts

@@ -389,7 +389,11 @@ export class AlertsStore {
   }
 
   async listSubscriptions(): Promise<PushSubscriptionRow[]> {
-    return this.db.query<PushSubscriptionRow>(`select * from alerts.push_subscriptions order by created_at`);
+    const rows = await this.db.query<PushSubscriptionRow>(`select * from alerts.push_subscriptions order by created_at`);
+    // #3702 decision 3: old stored prefs are not rewritten, but must not
+    // be reinterpreted on read. Apply the same per-field fallbacks used at
+    // intake so delivery and the prefs page see safe values.
+    return rows.map((row) => ({ ...row, quiet: mergeQuiet(row.quiet) }));
   }
 
   /** Design §4: a 404/410 marks the subscription gone; two consecutive

pm-stack/aggregator/test/alerts.test.ts

@@ -136,6 +136,57 @@ describe("class + quiet merges (design §1/§2)", () => {
   });
 });
 
+describe("stored subscription preference reads (#4978)", () => {
+  test("invalid stored quiet fields fall back per field without rewriting rows", async () => {
+    const invalidQuiet = { start: "99:99", end: "24:60", tz: "Not/AZone", enabled: true };
+    const validQuiet = { start: "22:30", end: "06:15", tz: "UTC", enabled: true };
+    const rawRows: PushSubscriptionRow[] = [
+      {
+        id: "sub-invalid",
+        endpoint: "https://push.example/invalid",
+        p256dh: "p256dh",
+        auth: "auth",
+        classes: { incident: true },
+        quiet: invalidQuiet,
+        user_agent: null,
+        created_at: "2026-11-01T00:00:00Z",
+        last_seen_at: "2026-11-01T00:00:00Z",
+        gone_count: 0,
+      },
+      {
+        id: "sub-valid",
+        endpoint: "https://push.example/valid",
+        p256dh: "p256dh",
+        auth: "auth",
+        classes: { incident: true },
+        quiet: validQuiet,
+        user_agent: null,
+        created_at: "2026-11-02T00:00:00Z",
+        last_seen_at: "2026-11-02T00:00:00Z",
+        gone_count: 0,
+      },
+    ];
+    const queries: string[] = [];
+    const db: SupabaseClient = {
+      ref: "test",
+      async query<T>(sql: string): Promise<T[]> {
+        queries.push(sql);
+        return rawRows as unknown as T[];
+      },
+    };
+
+    const loaded = await new AlertsStore(db).listSubscriptions();
+
+    expect(loaded.map((row) => row.quiet)).toEqual([
+      { start: "23:00", end: "07:00", tz: "America/Chicago", enabled: true },
+      validQuiet,
+    ]);
+    expect(inQuietHours(loaded[0].quiet, new Date("2026-01-15T12:00:00Z"))).toBe(true);
+    expect(rawRows.map((row) => row.quiet)).toEqual([invalidQuiet, validQuiet]);
+    expect(queries).toEqual(["select * from alerts.push_subscriptions order by created_at"]);
+  });
+});
+
 const incident: Incident = {
   id: "11111111-2222-3333-4444-555555555555",
   source: "globalping-watch",