diff --git a/web/hwlab-cloud-web/scripts/check.ts b/web/hwlab-cloud-web/scripts/check.ts
index 9fd23bae..996959d3 100644
--- a/web/hwlab-cloud-web/scripts/check.ts
+++ b/web/hwlab-cloud-web/scripts/check.ts
@@ -181,6 +181,7 @@ assert.doesNotMatch(workbenchStoreSource, /subscribeToTrace|TRACE_POLL_INTERVAL_
 assertIncludes(workbenchRefreshRuntimeSource, "if (existing)", "Scheduled refresh runtime must coalesce instead of resetting timers under SSE error storms");
 assertIncludes(workbenchRefreshRuntimeSource, "replaceTimer", "Scheduled refresh runtime must make replacement explicit instead of ad hoc timer resets");
 assertIncludes(workbenchPerformanceSource, "recordWorkbenchRuntimeDiagnostic", "Workbench performance probe must record runtime diagnostics for monitor root cause visibility");
+assertIncludes(workbenchPerformanceSource, "clearResourceTimings", "Workbench performance probe must bound browser ResourceTiming retention after API enrichment");
 assertIncludes(workbenchStoreSource, "recordWorkbenchRuntimeDiagnostic", "Workbench store must surface SSE recovery diagnostics to the performance probe");
 assertIncludes(workbenchRealtimePlanSource, "new Set(recovery.actions)", "Realtime recovery planner must consume transport-owned actions explicitly");
 assertIncludes(workbenchRealtimePlanSource, "actions.has(\"schedule-session-list\")", "Realtime stream errors must schedule bounded session list refreshes only when transport requests that action");
diff --git a/web/hwlab-cloud-web/scripts/workbench-performance.test.ts b/web/hwlab-cloud-web/scripts/workbench-performance.test.ts
index 275c4d63..b7ffff79 100644
--- a/web/hwlab-cloud-web/scripts/workbench-performance.test.ts
+++ b/web/hwlab-cloud-web/scripts/workbench-performance.test.ts
@@ -14,6 +14,7 @@ import {
   markWorkbenchSubmitApiAccepted,
   markWorkbenchTraceEventsReceived,
   markWorkbenchTraceProjected,
+  recordWorkbenchApiRequest,
   recordWorkbenchRuntimeDiagnostic,
   resetWorkbenchPerformanceForTest,
   startWorkbenchOpenJourney,
@@ -98,6 +99,44 @@ test("Workbench runtime diagnostics expose root cause labels without raw identif
   }
 });
 
+test("Workbench API timing enriches from ResourceTiming and clears the browser buffer", () => {
+  resetWorkbenchPerformanceForTest();
+  let clearCount = 0;
+  let configuredBufferSize = 0;
+  const startedAtEpochMs = 1_000_000;
+  const entries = [resourceTimingEntry({ name: "https://hwlab.example.test/v1/workbench/sessions/ses_secret/messages?limit=100", startTime: 10, duration: 42, responseStart: 37, responseEnd: 52 })];
+  const restoreBrowserRuntime = installBrowserProbeRuntime({
+    performance: {
+      timeOrigin: startedAtEpochMs - 10,
+      now: () => 123,
+      getEntriesByType: (type: string) => type === "resource" ? entries : [],
+      setResourceTimingBufferSize: (value: number) => {
+        configuredBufferSize = value;
+      },
+      clearResourceTimings: () => {
+        clearCount += 1;
+        entries.splice(0, entries.length);
+      }
+    }
+  });
+  try {
+    recordWorkbenchApiRequest({ route: "/v1/workbench/sessions/ses_secret/messages?limit=100", method: "GET", status: 200, outcome: "ok", startedAtEpochMs, endedAtEpochMs: startedAtEpochMs + 60 });
+
+    const events = drainWorkbenchPerformanceEventsForTest();
+    const event = events.find((item) => item.kind === "workbench_ui_event" && item.eventType === "api_request");
+    assert.equal(configuredBufferSize, 2000);
+    assert.equal(clearCount, 1);
+    assert.equal(entries.length, 0);
+    assert.equal(event?.route, "/v1/workbench/sessions/:id/messages");
+    assert.equal(event?.resourceDurationMs, 42);
+    assert.equal(event?.resourceRequestWaitMs, 15);
+    assert.equal(event?.resourceResponseTransferMs, 15);
+  } finally {
+    resetWorkbenchPerformanceForTest();
+    restoreBrowserRuntime();
+  }
+});
+
 test("Workbench session switch treats visible empty sessions as successful first paint", () => {
   resetWorkbenchPerformanceForTest();
   startWorkbenchSessionSwitch({ sessionId: "ses_empty_visible", source: "rail", targetState: "empty", cache: "cold" });
@@ -168,15 +207,18 @@ function traceOnlyAgentMessage(sessionId: string, traceId: string, events: Trace
   };
 }
 
-function installBrowserProbeRuntime(): () => void {
+function installBrowserProbeRuntime(options: { performance?: FakePerformance } = {}): () => void {
   const previousWindow = Object.getOwnPropertyDescriptor(globalThis, "window");
   const previousDocument = Object.getOwnPropertyDescriptor(globalThis, "document");
+  const previousPerformance = Object.getOwnPropertyDescriptor(globalThis, "performance");
   Object.defineProperty(globalThis, "window", {
     configurable: true,
     value: {
-      location: { pathname: "/workbench", hash: "" },
+      location: { href: "https://hwlab.example.test/workbench", pathname: "/workbench", hash: "" },
       crypto: globalThis.crypto,
-      addEventListener: () => undefined
+      addEventListener: () => undefined,
+      setTimeout: globalThis.setTimeout,
+      clearTimeout: globalThis.clearTimeout
     }
   });
   Object.defineProperty(globalThis, "document", {
@@ -186,13 +228,46 @@ function installBrowserProbeRuntime(): () => void {
       addEventListener: () => undefined
     }
   });
+  if (options.performance) {
+    Object.defineProperty(globalThis, "performance", {
+      configurable: true,
+      value: options.performance
+    });
+  }
   return () => {
     restoreGlobalProperty("window", previousWindow);
     restoreGlobalProperty("document", previousDocument);
+    restoreGlobalProperty("performance", previousPerformance);
   };
 }
 
-function restoreGlobalProperty(key: "window" | "document", descriptor: PropertyDescriptor | undefined): void {
+interface FakePerformance {
+  timeOrigin: number;
+  now: () => number;
+  getEntriesByType: (type: string) => unknown[];
+  setResourceTimingBufferSize?: (value: number) => void;
+  clearResourceTimings?: () => void;
+}
+
+function resourceTimingEntry(input: { name: string; startTime: number; duration: number; responseStart: number; responseEnd: number }): PerformanceResourceTiming {
+  return {
+    name: input.name,
+    startTime: input.startTime,
+    duration: input.duration,
+    fetchStart: input.startTime,
+    requestStart: input.startTime + 12,
+    responseStart: input.responseStart,
+    responseEnd: input.responseEnd,
+    transferSize: 1000,
+    encodedBodySize: 800,
+    decodedBodySize: 1600,
+    nextHopProtocol: "h2",
+    initiatorType: "fetch",
+    serverTiming: []
+  } as unknown as PerformanceResourceTiming;
+}
+
+function restoreGlobalProperty(key: "window" | "document" | "performance", descriptor: PropertyDescriptor | undefined): void {
   if (descriptor) {
     Object.defineProperty(globalThis, key, descriptor);
     return;
diff --git a/web/hwlab-cloud-web/src/utils/workbench-performance.ts b/web/hwlab-cloud-web/src/utils/workbench-performance.ts
index 5eae9212..be51af24 100644
--- a/web/hwlab-cloud-web/src/utils/workbench-performance.ts
+++ b/web/hwlab-cloud-web/src/utils/workbench-performance.ts
@@ -196,12 +196,13 @@ export function recordWorkbenchApiRequest(input: { route: string; method?: strin
   ensureInstalled();
   const endedAtEpochMs = input.endedAtEpochMs ?? wallNow();
   const resourceTiming = resourceTimingForApiRequest(route, input.startedAtEpochMs, endedAtEpochMs);
+  const routeLabel = routeTemplate(route);
   enqueueWorkbenchUiEvent({
     eventType: "api_request",
     loadingScope: "api",
     state: "request",
     reason: "api_request",
-    route,
+    route: routeLabel,
     method: input.method ?? "GET",
     status: input.status,
     statusClass: statusClass(input.status),
@@ -230,11 +231,8 @@ function resourceTimingForApiRequest(route: string, startedAtEpochMs: number, en
   const entries = performance.getEntriesByType("resource") as PerformanceResourceTiming[];
   const lowerBound = startedAtEpochMs - 2000;
   const upperBound = endedAtEpochMs + 2000;
-  const candidates = entries
-    .map((entry) => resourceTimingCandidate(entry, target, timeOrigin, lowerBound, upperBound, startedAtEpochMs))
-    .filter((candidate): candidate is ResourceTimingCandidate => candidate !== null)
-    .sort((left, right) => Number(right.queryExact) - Number(left.queryExact) || left.initiatorRank - right.initiatorRank || left.startDistanceMs - right.startDistanceMs);
-  const entry = candidates[0]?.entry;
+  const entry = bestResourceTimingEntry(entries, target, timeOrigin, lowerBound, upperBound, startedAtEpochMs);
+  clearCollectedResourceTimings(entries.length);
   if (!entry) return {};
   const result: Partial<WorkbenchPerformanceEvent> = {
     resourceDurationMs: roundedNonNegative(entry.duration),
@@ -257,6 +255,22 @@ interface ResourceTimingCandidate {
   startDistanceMs: number;
 }
 
+function bestResourceTimingEntry(entries: PerformanceResourceTiming[], target: URL, timeOrigin: number, lowerBound: number, upperBound: number, startedAtEpochMs: number): PerformanceResourceTiming | undefined {
+  let best: ResourceTimingCandidate | null = null;
+  for (const entry of entries) {
+    const candidate = resourceTimingCandidate(entry, target, timeOrigin, lowerBound, upperBound, startedAtEpochMs);
+    if (!candidate) continue;
+    if (!best || resourceTimingCandidateRank(candidate, best) < 0) best = candidate;
+  }
+  return best?.entry;
+}
+
+function resourceTimingCandidateRank(left: ResourceTimingCandidate, right: ResourceTimingCandidate): number {
+  return Number(right.queryExact) - Number(left.queryExact)
+    || left.initiatorRank - right.initiatorRank
+    || left.startDistanceMs - right.startDistanceMs;
+}
+
 function resourceTimingCandidate(entry: PerformanceResourceTiming, target: URL, timeOrigin: number, lowerBound: number, upperBound: number, startedAtEpochMs: number): ResourceTimingCandidate | null {
   if (!entry) return null;
   let url: URL;
@@ -277,6 +291,11 @@ function resourceTimingCandidate(entry: PerformanceResourceTiming, target: URL,
   };
 }
 
+function clearCollectedResourceTimings(entryCount: number): void {
+  if (entryCount <= 0 || typeof performance === "undefined" || typeof performance.clearResourceTimings !== "function") return;
+  performance.clearResourceTimings();
+}
+
 function resourceInitiatorRank(value: string): number {
   const initiator = safeText(value).toLowerCase();
   if (initiator === "fetch") return 0;
@@ -542,6 +561,7 @@ export function resetWorkbenchPerformanceForTest(): void {
   if (flushTimer !== null && hasBrowserTimerRuntime()) window.clearTimeout(flushTimer);
   flushTimer = null;
   installed = false;
+  resourceTimingBufferConfigured = false;
 }
 
 export function drainWorkbenchPerformanceEventsForTest(): WorkbenchPerformanceEvent[] {