diff --git a/web/hwlab-cloud-web/src/composables/useTraceSubscription.ts b/web/hwlab-cloud-web/src/composables/useTraceSubscription.ts
index 657e6c8f..df2e3b03 100644
--- a/web/hwlab-cloud-web/src/composables/useTraceSubscription.ts
+++ b/web/hwlab-cloud-web/src/composables/useTraceSubscription.ts
@@ -133,7 +133,11 @@ export function mergeRunnerTrace(previous: ChatMessage["runnerTrace"], next: Non
   };
 }
 
-function mergeTraceTimingProjection(previous: unknown, next: unknown): TraceSnapshot["timing"] | null {
+type TraceTimingMergeOptions = {
+  preserveVisibleTerminalDuration?: boolean;
+};
+
+function mergeTraceTimingProjection(previous: unknown, next: unknown, options: TraceTimingMergeOptions = {}): TraceSnapshot["timing"] | null {
   const previousTiming = traceTimingCandidate(previous);
   const nextTiming = traceTimingCandidate(next);
   if (!previousTiming && !nextTiming) return null;
@@ -142,12 +146,16 @@ function mergeTraceTimingProjection(previous: unknown, next: unknown): TraceSnap
   const startedAt = earliestTraceTimestamp(previousTiming.startedAt, nextTiming.startedAt);
   const lastEventAt = latestTraceTimestamp(previousTiming.lastEventAt, nextTiming.lastEventAt);
   const finishedAt = latestTraceTimestamp(previousTiming.finishedAt, nextTiming.finishedAt);
-  const elapsedDurationMs = traceElapsedMs(startedAt, finishedAt ?? lastEventAt);
+  const runningElapsedDurationMs = traceElapsedMs(startedAt, lastEventAt);
+  const terminalElapsedDurationMs = traceElapsedMs(startedAt, finishedAt);
   const terminalTiming = traceTimingIsTerminal(next) || finishedAt !== null;
   const previousTerminalDurationMs = previousTiming.finishedAt ? previousTiming.durationMs : null;
+  const preservedVisibleTerminalDurationMs = options.preserveVisibleTerminalDuration && !finishedAt
+    ? firstTraceDuration(previousTiming.durationMs)
+    : null;
   const durationMs = terminalTiming
-    ? maxTraceDuration(previousTiming.durationMs, nextTiming.durationMs, elapsedDurationMs, previousTerminalDurationMs)
-    : maxTraceDuration(previousTiming.durationMs, nextTiming.durationMs, elapsedDurationMs);
+    ? maxTraceDuration(finishedAt ? nextTiming.durationMs : null, terminalElapsedDurationMs, previousTerminalDurationMs, preservedVisibleTerminalDurationMs)
+    : maxTraceDuration(previousTiming.durationMs, nextTiming.durationMs, runningElapsedDurationMs);
   return {
     ...previousTiming,
     ...nextTiming,