Show elapsed time for live run summaries

frontend/app/components/assistant-ui/thread.tsx

@@ -1898,6 +1898,9 @@ const ActivityChainSummary: FC<{
 	const contentRunStartedAtMs = useAuiState((s) =>
 		findNumberInActivityParts(s.message.content, "runStartedAtMs"),
 	);
+	const messageCreatedAtMs = useAuiState((s) =>
+		normalizeMessageCreatedAtMs(s.message.createdAt),
+	);
 	const storedElapsedMs = useAuiState((s) => {
 		const value = readMetadataValue(s.message.metadata, "elapsedMs");
 		const contentValue = findElapsedMsInActivityParts(s.message.content);
@@ -1908,7 +1911,8 @@ const ActivityChainSummary: FC<{
 			? Math.max(0, Math.round(value))
 			: null;
 	});
-	const initialStartedAtMs = metadataRunStartedAtMs ?? contentRunStartedAtMs;
+	const initialStartedAtMs =
+		metadataRunStartedAtMs ?? contentRunStartedAtMs ?? messageCreatedAtMs;
 	const [elapsedMs, setElapsedMs] = useState<number | null>(() => {
 		if (storedElapsedMs !== null) return storedElapsedMs;
 		if (initialStartedAtMs !== null) {
@@ -1939,6 +1943,7 @@ const ActivityChainSummary: FC<{
 		const startedAt =
 			metadataRunStartedAtMs ??
 			contentRunStartedAtMs ??
+			messageCreatedAtMs ??
 			(storedElapsedMs === null ? null : Date.now() - storedElapsedMs);
 		if (startedAt === null) {
 			setElapsedMs(storedElapsedMs);
@@ -1949,7 +1954,13 @@ const ActivityChainSummary: FC<{
 			setElapsedMs(Math.max(0, Date.now() - startedAt));
 		}, 1000);
 		return () => window.clearInterval(timer);
-	}, [active, metadataRunStartedAtMs, contentRunStartedAtMs, storedElapsedMs]);
+	}, [
+		active,
+		metadataRunStartedAtMs,
+		contentRunStartedAtMs,
+		messageCreatedAtMs,
+		storedElapsedMs,
+	]);
 
 	return (
 		<button
@@ -1991,6 +2002,23 @@ function findNumberInActivityParts(
 	return null;
 }
 
+function normalizeMessageCreatedAtMs(value: unknown) {
+	if (value instanceof Date) {
+		const time = value.getTime();
+		return Number.isFinite(time) ? time : null;
+	}
+	if (typeof value === "number" && Number.isFinite(value)) {
+		return value < 10_000_000_000
+			? Math.round(value * 1000)
+			: Math.round(value);
+	}
+	if (typeof value === "string") {
+		const time = Date.parse(value);
+		return Number.isFinite(time) ? time : null;
+	}
+	return null;
+}
+
 function findElapsedMsInActivityParts(content: readonly ActivitySummaryPart[]) {
 	for (const part of content) {
 		if (typeof part.elapsedMs === "number" && Number.isFinite(part.elapsedMs)) {