diff --git a/apps/web/src/routes/(app)/p/[actor]/e/[rkey]/og.png/+server.ts b/apps/web/src/routes/(app)/p/[actor]/e/[rkey]/og.png/+server.ts
index ae25e51..ef81903 100644
--- a/apps/web/src/routes/(app)/p/[actor]/e/[rkey]/og.png/+server.ts
+++ b/apps/web/src/routes/(app)/p/[actor]/e/[rkey]/og.png/+server.ts
@@ -7,6 +7,66 @@ import { flattenEventRecord, getEventRecordFromContrail, getServerClient } from
 import { formatInTz, partsInTz } from '@atmo-dev/events-ui';
 import { render } from 'svelte/server';
 
+// Short, REVALIDATING cache policy for the OG image. Overrides the library's
+// year-long, non-revalidating default that froze social cards at CDNs and
+// scrapers, so event edits (renamed event, new date, new thumbnail) never
+// surfaced (flo-bit/atmo-events#41). 5m browser / 1h CDN / 1d stale-while-
+// revalidate lets edits propagate while keeping unchanged cards cheap.
+const CACHE_CONTROL = 'public, max-age=300, s-maxage=3600, stale-while-revalidate=86400';
+
+/** FNV-1a 32-bit hash to 8-char hex. Deterministic and header-safe. */
+function fnv1a(input: string): string {
+	let h = 0x811c9dc5;
+	for (let i = 0; i < input.length; i++) {
+		h ^= input.charCodeAt(i);
+		h = Math.imul(h, 0x01000193);
+	}
+	return (h >>> 0).toString(16).padStart(8, '0');
+}
+
+/**
+ * Weak ETag for the OG image. The ATProto record CID rolls whenever the event
+ * record's content changes, making it an ideal validator. contrail can hand back
+ * a null CID (see flattenEventRecord), so fall back to a hash of every field the
+ * rendered card depends on: name, start time, timezone (it sets the date line),
+ * and media (the thumbnail). A conditional GET then keeps returning 304 for an
+ * unchanged card, while any edit that changes the image also changes the ETag.
+ */
+function ogEtag(event: {
+	cid?: string | null;
+	rkey: string;
+	startsAt: string;
+	name: string;
+	timezone?: string | null;
+	media?: unknown;
+}): string {
+	const basis =
+		event.cid ??
+		`f${fnv1a(
+			JSON.stringify([
+				event.rkey,
+				event.startsAt,
+				event.name,
+				event.timezone ?? '',
+				event.media ?? null
+			])
+		)}`;
+	return `W/"${basis}"`;
+}
+
+/**
+ * RFC 7232 weak If-None-Match evaluation: matches when the client presents `*`
+ * or any tag equal to our ETag under weak comparison (the `W/` prefix is ignored
+ * on both sides). Used to short-circuit an unchanged card to a bare 304.
+ */
+function ifNoneMatchSatisfied(header: string | null, etag: string): boolean {
+	if (!header) return false;
+	if (header.trim() === '*') return true;
+	const stripWeak = (v: string) => v.trim().replace(/^W\//, '');
+	const target = stripWeak(etag);
+	return header.split(',').some((tag) => stripWeak(tag) === target);
+}
+
 function formatDate(dateStr: string, tz: string | undefined): string {
 	// Render in the event's authored timezone when known so OG images match
 	// what the event page shows, regardless of the edge server's local zone.
@@ -16,7 +76,7 @@ function formatDate(dateStr: string, tz: string | undefined): string {
 	return `${weekday}, ${month} ${day}`;
 }
 
-export async function GET({ params, platform }) {
+export async function GET({ params, platform, request }) {
 	const { rkey } = params;
 
 	const did = await getActor(params.actor);
@@ -40,6 +100,16 @@ export async function GET({ params, platform }) {
 		throw error(404, 'Event not found');
 	}
 
+	// Serve the validator before doing any rendering work: a matching conditional
+	// GET returns a bare 304 (no body, no render) so unchanged cards stay cheap.
+	const etag = ogEtag(eventData);
+	if (ifNoneMatchSatisfied(request.headers.get('if-none-match'), etag)) {
+		return new Response(null, {
+			status: 304,
+			headers: { 'Cache-Control': CACHE_CONTROL, ETag: etag }
+		});
+	}
+
 	const dateStr = formatDate(eventData.startsAt, eventData.timezone);
 
 	let thumbnailUrl: string | null = null;
@@ -62,8 +132,14 @@ export async function GET({ params, platform }) {
 		.replace(/&quot;/g, '"')
 		.replace(/&#39;/g, "'");
 
-	return new ImageResponse(
-		decoded,
-		{ width: 1200, height: 630, debug: false, format: 'png' }
-	);
+	// The `headers` override is spread LAST by @ethercorps/sveltekit-og, so it
+	// wins over the library's baked-in year-long default and serves our
+	// revalidating policy + validator instead.
+	return new ImageResponse(decoded, {
+		width: 1200,
+		height: 630,
+		debug: false,
+		format: 'png',
+		headers: { 'Cache-Control': CACHE_CONTROL, ETag: etag }
+	});
 }