diff --git a/web/hwlab-cloud-web/src/stores/workbench.ts b/web/hwlab-cloud-web/src/stores/workbench.ts
index 66d704a0..a7adcd0f 100644
--- a/web/hwlab-cloud-web/src/stores/workbench.ts
+++ b/web/hwlab-cloud-web/src/stores/workbench.ts
@@ -960,15 +960,10 @@ function nonBlockingProjection(projection: ProjectionDiagnostic | null): Project
   }
 
   function hydrateTerminalTraceGaps(source: ChatMessage[], reason: string): void {
-    for (const message of terminalTraceHydrationGaps(source)) {
-      const traceId = firstNonEmptyString(message.traceId, message.runnerTrace?.traceId);
-      if (traceId && activeSessionId.value) recordActivity(`${reason}:${traceId}`);
-      void hydrateTraceEventsForMessage(message, { force: true });
-    }
-  }
-
-  function terminalTraceHydrationGaps(source: ChatMessage[]): ChatMessage[] {
-    return source.filter(messageNeedsTerminalTraceGapHydration).slice(-TRACE_HYDRATION_AUTO_QUEUE_LIMIT).reverse();
+    // Terminal trace rows are loaded on explicit force/detail paths. Auto-filling
+    // historical terminal traces makes multi-turn Workbench sessions main-thread bound.
+    void source;
+    void reason;
   }
 
   function scheduleForcedTraceHydrationRetry(message: ChatMessage): void {
@@ -1232,13 +1227,13 @@ function nonBlockingProjection(projection: ProjectionDiagnostic | null): Project
     }
     const ownerMessages = ownerSessionId ? serverState.value.messagesBySessionId[ownerSessionId] ?? [] : messages.value;
     const message = latestMessageForTrace(id, ownerMessages);
-    if (message) await hydrateTraceEventsForMessage(message, { force: true });
     const turn = turnStatusAuthority.value[id];
     const terminal = turn?.terminal === true || isTerminalMessageStatus(turn?.status) || isTerminalMessageStatus(message?.status);
     if (terminal) {
       clearActiveTraceRestGapFill(id);
       return;
     }
+    if (message) await hydrateTraceEventsForMessage(message, { force: true });
     const stillActive = currentRequest.value?.traceId === id || isTraceActiveStatus(turn?.status) || isTraceActiveStatus(message?.status);
     if (stillActive) scheduleActiveTraceRestGapFill(id, "active-rest-gap:repeat", WORKBENCH_ACTIVE_TRACE_REST_GAP_FILL_REPEAT_MS);
   }
@@ -1416,9 +1411,7 @@ function nonBlockingProjection(projection: ProjectionDiagnostic | null): Project
       if (ownerSessionId) await refreshMessageProjectionForTrace(ownerSessionId, id, { force: true });
       const ownerMessages = ownerSessionId ? serverState.value.messagesBySessionId[ownerSessionId] ?? [] : messages.value;
       const message = latestMessageForTrace(id, ownerMessages);
-      if (message) {
-        await hydrateTraceEventsForMessage(message, { force: true });
-      } else if (ownerSessionId) {
+      if (!message && ownerSessionId) {
         await refreshRealtimeSessionMessages(ownerSessionId, `${reason}:message-gap`, { force: true });
       }
     } finally {
@@ -1540,7 +1533,6 @@ function nonBlockingProjection(projection: ProjectionDiagnostic | null): Project
     const ownerMessages = serverState.value.messagesBySessionId[ownerSessionId] ?? [];
     const terminalMessage = latestMessageForTrace(traceId, ownerMessages);
     if (options.forceRead && terminalMessage) void hydrateTraceEventsForMessage(terminalMessage, { force: true });
-    else void hydrateTraceEvents(ownerMessages);
     if (options.forceRead) void refreshSessions(ownerSessionId, { force: true });
     if (ownerSessionId === activeSessionId.value) {
       chatPending.value = false;
@@ -2479,6 +2471,7 @@ function messageNeedsTraceHydration(message: ChatMessage): boolean {
   if (message.role !== "agent") return false;
   const traceId = firstNonEmptyString(message.traceId, message.runnerTrace?.traceId);
   if (!traceId) return false;
+  if (!messageHasActiveTraceForHydration(message)) return false;
   const trace = message.runnerTrace;
   const events = Array.isArray(trace?.events) ? trace.events : [];
   const eventCount = firstFiniteNumber(trace?.eventCount) ?? events.length;
@@ -2486,17 +2479,11 @@ function messageNeedsTraceHydration(message: ChatMessage): boolean {
   return events.length === 0 || trace?.eventsCompacted === true || trace?.fullTraceLoaded !== true;
 }
 
-function messageNeedsTerminalTraceGapHydration(message: ChatMessage): boolean {
-  if (!messageHasCompletedFinalResponse(message)) return false;
-  const traceId = firstNonEmptyString(message.traceId, message.runnerTrace?.traceId);
-  if (!traceId) return false;
+function messageHasActiveTraceForHydration(message: ChatMessage): boolean {
   const trace = message.runnerTrace;
-  if (!trace) return true;
-  const events = Array.isArray(trace.events) ? trace.events : [];
-  const eventCount = firstFiniteNumber(trace.eventCount) ?? events.length;
-  if (trace.eventsCompacted === true || trace.fullTraceLoaded !== true) return true;
-  if (events.length === 0 && eventCount > 0) return true;
-  return isTraceActiveStatus(trace.status) || isTraceActiveStatus(trace.traceStatus);
+  return isTraceActiveStatus(message.status)
+    || isTraceActiveStatus(trace?.status)
+    || isTraceActiveStatus(trace?.traceStatus);
 }
 
 function traceHasCompletedFinalResponse(traceId: string | null | undefined, source: ChatMessage[]): boolean {