diff --git a/src/notifier/notifier.test.ts b/src/notifier/notifier.test.ts
index 8573d81..71e7bf1 100644
--- a/src/notifier/notifier.test.ts
+++ b/src/notifier/notifier.test.ts
@@ -9,11 +9,14 @@ import { TIMEZONE } from "./schedule.ts";
 
 const zdt = (s: string) => Temporal.ZonedDateTime.from(`${s}[${TIMEZONE}]`);
 
+// Start/end dates use the UTC `Z` designator, matching what the OpenMeet API
+// actually returns (see slack.test.ts fixtures). The notifier parses these as
+// instants and renders them in TIMEZONE for digest-window comparisons.
 const ev = (
   slug: string,
-  startDate = "2026-06-10T18:00:00",
+  startDate = "2026-06-10T18:00:00Z",
   name = slug,
-  endDate = "2026-06-15T20:00:00",
+  endDate = "2026-06-15T20:00:00Z",
 ): OpenMeetEvent => ({ name, slug, startDate, endDate });
 
 // A Config with only the fields the notifier reads. The injected client
@@ -172,10 +175,10 @@ test("start: new-event notifications and the weekly digest both fire in the same
   let t = zdt("2026-06-08T06:00:00");
   const now = () => t;
 
-  const prime = [ev("known", "2026-06-10T18:00:00")];
+  const prime = [ev("known", "2026-06-10T18:00:00Z")];
   const withNew = [
-    ev("known", "2026-06-10T18:00:00"),
-    ev("fresh", "2026-06-11T18:00:00"), // new this iteration, and in the digest window
+    ev("known", "2026-06-10T18:00:00Z"),
+    ev("fresh", "2026-06-11T18:00:00Z"), // new this iteration, and in the digest window
   ];
   const client = fakeClient([prime, withNew], aborter, (i) => {
     if (i === 1) t = zdt("2026-06-08T08:00:00"); // advance past the 07:30 digest
@@ -241,13 +244,15 @@ test("start: weekly digest fires at the scheduled time and only includes events
   let t = zdt("2026-06-08T06:00:00");
   const now = () => t;
 
+  // now advances to 2026-06-08T08:00:00 [America/Chicago] = 13:00Z (CDT, UTC-5),
+  // so now+7d = 2026-06-15T13:00:00Z.
   const events = [
-    ev("past", "2026-06-07T18:00:00"), // before now -> excluded
-    ev("today", "2026-06-08T18:00:00"), // in window -> included
-    ev("midweek", "2026-06-10T18:00:00"), // in window -> included
-    ev("lateweek", "2026-06-14T18:00:00"), // in window -> included
-    ev("boundary", "2026-06-15T08:00:00"), // == now+7d, excluded (strict <)
-    ev("beyond", "2026-06-20T18:00:00"), // outside window -> excluded
+    ev("past", "2026-06-07T18:00:00Z"), // before now -> excluded
+    ev("today", "2026-06-08T18:00:00Z"), // in window -> included
+    ev("midweek", "2026-06-10T18:00:00Z"), // in window -> included
+    ev("lateweek", "2026-06-14T18:00:00Z"), // in window -> included
+    ev("boundary", "2026-06-15T13:00:00Z"), // == now+7d, excluded (strict <)
+    ev("beyond", "2026-06-20T18:00:00Z"), // outside window -> excluded
   ];
 
   const client = fakeClient([events, events], aborter, (i) => {
diff --git a/src/notifier/notifier.ts b/src/notifier/notifier.ts
index 59214d8..d01d049 100644
--- a/src/notifier/notifier.ts
+++ b/src/notifier/notifier.ts
@@ -69,7 +69,10 @@ export async function newNotifier({
             const nowZdt = now();
             const oneWeekFromNow = nowZdt.add({ days: 7 });
             const eventsInNextWeek = events.filter((e) => {
-              const start = Temporal.PlainDateTime.from(e.startDate).toZonedDateTime(TIMEZONE);
+              // OpenMeet returns startDate as a UTC instant (e.g. "2026-06-22T12:31:00Z");
+              // PlainDateTime.from rejects the Z designator, so parse as an Instant
+              // and render it in our local timezone for the digest-window compare.
+              const start = Temporal.Instant.from(e.startDate).toZonedDateTimeISO(TIMEZONE);
               return (
                 Temporal.ZonedDateTime.compare(start, nowZdt) >= 0 &&
                 Temporal.ZonedDateTime.compare(start, oneWeekFromNow) < 0