Let a pinned minute read runs from the whole day

/observability/runs gains since/until, so the throughput chart's pin asks
the server for its minute instead of filtering a fixed recent list. This
engine writes ~60 runs a minute, so any minute but the newest read empty.

since is inclusive and until exclusive, matching the minute buckets the
charts are drawn from. Hover stays the client-side preview it was:
scrubbing a day would otherwise be a request per minute rested on.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017MeiWk3Yq12n2pTvnQWYvt

frontend/src/components/Health/HealthActivity.tsx

@@ -17,6 +17,7 @@ import {
   failuresQueryOptions,
   healthKeys,
   minuteOf,
+  minuteRunsQueryOptions,
   runsQueryOptions,
   timeseriesQueryOptions,
 } from "./queries"
@@ -174,6 +175,7 @@ export function HealthActivity() {
 
   const { data: series } = useQuery(timeseriesQueryOptions())
   const { data: runs } = useQuery(runsQueryOptions())
+  const { data: pinnedRuns } = useQuery(minuteRunsQueryOptions(runsAt.pinned))
   const { data: failures } = useQuery(failuresQueryOptions())
   const { data: audit } = useQuery(auditQueryOptions())
   const { data: dead } = useQuery(deadLetterQueryOptions())
@@ -201,10 +203,16 @@ export function HealthActivity() {
   ): HistoryPoint[] =>
     points.map((point) => ({ ts: point.ts, value: pick(point) }))
 
+  // A pin is read back from the server, so it reaches a minute the recent list
+  // is nowhere near deep enough to hold. A hover stays the client-side preview
+  // it is: scrubbing a day's chart would otherwise be a request per minute the
+  // pointer rests on.
   const shownRuns =
-    runsAt.at === null
-      ? (runs ?? []).slice(0, RUNS_SHOWN)
-      : (runs ?? []).filter((run) => minuteOf(run.started_at) === runsAt.at)
+    runsAt.pinned !== null
+      ? (pinnedRuns ?? [])
+      : runsAt.at === null
+        ? (runs ?? []).slice(0, RUNS_SHOWN)
+        : (runs ?? []).filter((run) => minuteOf(run.started_at) === runsAt.at)
   const shownFailures =
     failuresAt.at === null
       ? (failures ?? []).slice(0, FAILURES_SHOWN)
@@ -282,7 +290,9 @@ export function HealthActivity() {
               <p className="text-sm text-muted-foreground">
                 {runsAt.at === null
                   ? "No runs recorded yet."
-                  : "No run from this minute is in the recent list."}
+                  : runsAt.pinned !== null
+                    ? "Nothing ran in this minute."
+                    : "No run from this minute is in the recent list."}
               </p>
             )}
           </div>

frontend/src/components/Health/queries.ts

@@ -9,13 +9,10 @@ const REFRESH = 30_000
 /**
  * How deep the run and failure lists are read.
  *
- * Deeper than they are shown: picking a minute off a chart filters these rows
+ * Deeper than they are shown: hovering a minute on a chart previews these rows
  * client-side, and a list holding only the newest handful would have nothing
- * to find for any minute but the current one.
- *
- * ponytail: the runs endpoint caps at 200 and takes no time range, so a busy
- * engine still only covers its last minute or so. A `since` parameter is what
- * would let a moment on the chart reach the whole day.
+ * to show for any minute but the current one. Pinning asks the server for the
+ * minute instead, which is what reaches past this depth.
  */
 const RUN_DEPTH = 200
 const EVENT_DEPTH = 100
@@ -53,6 +50,26 @@ export const runsQueryOptions = () => ({
   refetchInterval: REFRESH,
 })
 
+/**
+ * The runs of one minute, wherever it sits in the day.
+ *
+ * A busy engine writes more runs per minute than the recent list is deep, so a
+ * pinned moment is asked for rather than filtered out of what is already held.
+ * `at` is a minute start, and the window is that minute.
+ */
+export const minuteRunsQueryOptions = (at: number | null) => ({
+  queryKey: ["observability", "runs", at] as const,
+  queryFn: () =>
+    ObservabilityService.readRuns({
+      since: new Date((at ?? 0) * 1000).toISOString(),
+      until: new Date(((at ?? 0) + 60) * 1000).toISOString(),
+      limit: RUN_DEPTH,
+    }),
+  // A minute that has passed does not change, and the current one is refreshed
+  // by the unpinned list anyway.
+  enabled: at !== null,
+})
+
 export const failuresQueryOptions = () => ({
   queryKey: [...healthKeys.events, "failure"] as const,
   queryFn: () =>