admin: live ring capacity is injectable, eviction test no longer timing-bound

admin/src/features/activity/useLiveQueries.ts

@@ -24,6 +24,12 @@ export interface LiveQueriesOptions {
 	fetchSince?: (since: number) => Promise<QueriesPage>;
 	/** Cheap session-gated GET fired once on entering capped, to distinguish an expired session from a real cap. */
 	probeSession?: () => Promise<unknown>;
+	/**
+	 * Ring size. Injectable so a test can provoke an eviction with a handful of
+	 * rows instead of pushing 500 frames through React state; the app never
+	 * passes it, and the operator never sees it.
+	 */
+	capacity?: number;
 }
 
 // A transient drop is invisible to EventSource beyond a bare `error` event;
@@ -34,7 +40,10 @@ export interface LiveQueriesOptions {
 export const CAP_ERROR_THRESHOLD = 3;
 
 const defaultEventSource: EventSourceFactory = (url) => new EventSource(url);
-const defaultFetchSince = (since: number): Promise<QueriesPage> => api.getQueries({ since, limit: RING_CAPACITY });
+const defaultFetchSince =
+	(capacity: number) =>
+	(since: number): Promise<QueriesPage> =>
+		api.getQueries({ since, limit: capacity });
 const defaultProbeSession = (): Promise<unknown> => api.getPause();
 
 function isUnauthorized(error: unknown): boolean {
@@ -79,7 +88,8 @@ export function useLiveQueries(options?: LiveQueriesOptions): LiveQueries {
 		errorsRef.current = 0;
 		setStatus("connecting");
 		const opts = optionsRef.current;
-		const fetchSince = opts?.fetchSince ?? defaultFetchSince;
+		const capacity = opts?.capacity ?? RING_CAPACITY;
+		const fetchSince = opts?.fetchSince ?? defaultFetchSince(capacity);
 		const probeSession = opts?.probeSession ?? defaultProbeSession;
 		const es = (opts?.createEventSource ?? defaultEventSource)(opts?.url ?? api.liveQueriesUrl);
 		esRef.current = es;
@@ -94,7 +104,7 @@ export function useLiveQueries(options?: LiveQueriesOptions): LiveQueries {
 				fetchSince(since).then(
 					(page) => {
 						if (esRef.current !== es) return;
-						const merged = mergeGap(bufferRef.current, page.queries, () => ++keyRef.current);
+						const merged = mergeGap(bufferRef.current, page.queries, () => ++keyRef.current, capacity);
 						bufferRef.current = merged.rows;
 						setRows(merged.rows);
 						setMissed(merged.missed);
@@ -122,11 +132,11 @@ export function useLiveQueries(options?: LiveQueriesOptions): LiveQueries {
 				return;
 			}
 			lastSeenTsRef.current = payload.request.time;
-			bufferRef.current = pushRow(bufferRef.current, {
-				kind: "streamed",
-				event: payload,
-				key: ++keyRef.current,
-			});
+			bufferRef.current = pushRow(
+				bufferRef.current,
+				{ kind: "streamed", event: payload, key: ++keyRef.current },
+				capacity,
+			);
 			setRows(bufferRef.current);
 		});