diff --git a/internal/cloud/server-code-agent-http.ts b/internal/cloud/server-code-agent-http.ts
index 6bb98706..b63fa877 100644
--- a/internal/cloud/server-code-agent-http.ts
+++ b/internal/cloud/server-code-agent-http.ts
@@ -2518,15 +2518,7 @@ export async function handleCodeAgentTraceHttp(request, response, url, options)
         await recordCodeAgentSessionOwner({ payload: agentRunResult, params: agentRunResult, options, status: codeAgentOwnerStatusForResult(agentRunResult), preserveLastTraceId: true });
       }
     } catch (error) {
-      sendJson(response, Number(error?.statusCode ?? 502), {
-        error: {
-          code: error?.code ?? "agentrun_trace_command_result_unavailable",
-          message: error?.message ?? "AgentRun command result could not be resolved for this traceId",
-          traceId,
-          valuesPrinted: false
-        }
-      });
-      return;
+      refreshError = error;
     }
   }
 
diff --git a/scripts/web-live-dom-probe.mjs b/scripts/web-live-dom-probe.mjs
index 40a039d6..4a280992 100644
--- a/scripts/web-live-dom-probe.mjs
+++ b/scripts/web-live-dom-probe.mjs
@@ -56,6 +56,8 @@ export function parseProbeArgs(argv) {
     conversationId: process.env.HWLAB_WEB_PROBE_CONVERSATION_ID ?? "",
     waitMessagesMs: 2500,
     waitAgentTerminalMs: Number(process.env.HWLAB_WEB_PROBE_WAIT_AGENT_TERMINAL_MS ?? "0"),
+    traceSampleCount: envNonNegativeInteger("HWLAB_WEB_PROBE_TRACE_SAMPLE_COUNT", 0),
+    traceSampleIntervalMs: envNonNegativeInteger("HWLAB_WEB_PROBE_TRACE_SAMPLE_INTERVAL_MS", 0),
     reportPath: tempReportPath("web-live-dom-probe.json"),
     screenshotPath: tempReportPath("web-live-dom-probe.png"),
     jobId: ""
@@ -90,6 +92,8 @@ export function parseProbeArgs(argv) {
     else if (arg === "--wait-after-submit-ms" || arg.startsWith("--wait-after-submit-ms=")) args.waitAfterSubmitMs = positiveInteger(readValue("--wait-after-submit-ms"), "--wait-after-submit-ms");
     else if (arg === "--wait-messages-ms" || arg.startsWith("--wait-messages-ms=")) args.waitMessagesMs = positiveInteger(readValue("--wait-messages-ms"), "--wait-messages-ms");
     else if (arg === "--wait-agent-terminal-ms" || arg.startsWith("--wait-agent-terminal-ms=")) args.waitAgentTerminalMs = positiveInteger(readValue("--wait-agent-terminal-ms"), "--wait-agent-terminal-ms");
+    else if (arg === "--trace-sample-count" || arg.startsWith("--trace-sample-count=")) args.traceSampleCount = nonNegativeInteger(readValue("--trace-sample-count"), "--trace-sample-count");
+    else if (arg === "--trace-sample-interval-ms" || arg.startsWith("--trace-sample-interval-ms=")) args.traceSampleIntervalMs = nonNegativeInteger(readValue("--trace-sample-interval-ms"), "--trace-sample-interval-ms");
     else if (arg === "--timeout-ms" || arg.startsWith("--timeout-ms=")) args.timeoutMs = positiveInteger(readValue("--timeout-ms"), "--timeout-ms");
     else if (arg === "--fresh-session") args.freshSession = true;
     else if (arg === "--no-cancel-running") args.cancelRunning = false;
@@ -219,6 +223,7 @@ export async function runProbe(args) {
   let browser;
   let page;
   let result;
+  let traceSamples = [];
   if (args.credentialError) {
     result = {
       ok: false,
@@ -258,7 +263,9 @@ export async function runProbe(args) {
     if (args.conversationId) await selectConversationInBrowserSession(page, args, actions);
     if (args.freshSession) await createFreshSession(page, args, actions);
     if (args.message) await submitPrompt(page, args, actions);
+    if (args.message && args.traceSampleCount > 0) traceSamples = await sampleTraceTimeline(page, args, actions);
     if (args.waitAgentTerminalMs) await waitForAgentTerminal(page, args, actions);
+    if (args.message && args.cancelRunning) await maybeClick(page, ".message-action-cancel", actions, "cancel-running-message");
     await waitForMessageCards(page, args, actions);
     await page.screenshot({ path: screenshotPath, fullPage: true });
     const dom = await collectDomEvidence(page, args);
@@ -276,6 +283,7 @@ export async function runProbe(args) {
       actions,
       credentials: args.credentials,
       bootstrapRoutes: summarizeBootstrapRoutes(bootstrapRoutes),
+      traceSamples,
       dom,
       promptValidation,
       artifacts: { reportPath, screenshotPath },
@@ -286,6 +294,7 @@ export async function runProbe(args) {
         conversationSelected: Boolean(args.conversationId),
         freshSessionRequested: args.freshSession,
         promptSubmitted: Boolean(args.message),
+        traceSamplingRequested: args.traceSampleCount > 0,
         cancelRunningRequested: args.cancelRunning
       }
     };
@@ -346,6 +355,7 @@ async function collectFailureDomEvidence(page) {
 
 function validatePromptFinalResponse(dom, args) {
   if (!args.message) return { ok: true, applicable: false, reason: "no-prompt-submitted" };
+  if (args.traceSampleCount > 0 && !args.waitAgentTerminalMs) return { ok: true, applicable: false, reason: "trace-sampling-without-terminal-wait" };
   const messages = Array.isArray(dom.messages) ? dom.messages : [];
   const latestAgent = [...messages].reverse().find((message) => message.role === "agent");
   const finalResponse = latestAgent?.finalResponse ?? null;
@@ -402,6 +412,7 @@ async function startProbe(args) {
     "--wait-messages-ms", String(args.waitMessagesMs)
   ];
   if (args.waitAgentTerminalMs > 0) childArgs.push("--wait-agent-terminal-ms", String(args.waitAgentTerminalMs));
+  if (args.traceSampleCount > 0) childArgs.push("--trace-sample-count", String(args.traceSampleCount), "--trace-sample-interval-ms", String(args.traceSampleIntervalMs));
   if (args.freshSession) childArgs.push("--fresh-session");
   if (!args.cancelRunning) childArgs.push("--no-cancel-running");
   if (args.conversationId) childArgs.push("--conversation-id", args.conversationId);
@@ -425,6 +436,7 @@ async function startProbe(args) {
     url: args.url,
     projectId: args.projectId,
     conversationId: args.conversationId || null,
+    traceSampling: args.traceSampleCount > 0 ? { count: args.traceSampleCount, intervalMs: args.traceSampleIntervalMs } : null,
     reportPath,
     screenshotPath,
     stdoutPath,
@@ -659,7 +671,42 @@ async function submitPrompt(page, args, actions) {
   const afterClick = await collectCommandState(page);
   actions.push({ action: "submit-prompt", chars: args.message.length, readyBefore, afterFill, afterClick });
   await page.waitForTimeout(args.waitAfterSubmitMs);
-  if (args.cancelRunning) await maybeClick(page, ".message-action-cancel", actions, "cancel-running-message");
+}
+
+async function sampleTraceTimeline(page, args, actions) {
+  const samples = [];
+  for (let index = 0; index < args.traceSampleCount; index += 1) {
+    if (index > 0 && args.traceSampleIntervalMs > 0) await page.waitForTimeout(args.traceSampleIntervalMs);
+    samples.push(await collectTraceTimelineSample(page, index));
+  }
+  actions.push({ action: "trace-interval-samples", count: samples.length, intervalMs: args.traceSampleIntervalMs, samples });
+  return samples;
+}
+
+async function collectTraceTimelineSample(page, index) {
+  return page.evaluate((sampleIndex) => {
+    const cards = [...document.querySelectorAll(".message-card")];
+    const latestAgent = [...cards].reverse().find((card) => card.getAttribute("data-message-role") === "agent" || card.classList.contains("message-agent"));
+    const trace = latestAgent?.querySelector(".trace-timeline") ?? null;
+    const details = trace?.querySelector("details") ?? null;
+    const rows = latestAgent ? [...latestAgent.querySelectorAll(".trace-render-row")] : [];
+    const latestRow = rows.at(-1) ?? null;
+    const empty = latestAgent?.querySelector(".trace-empty") ?? null;
+    const finalResponse = latestAgent?.querySelector(".message-final-response") ?? null;
+    return {
+      index: sampleIndex,
+      sampledAt: new Date().toISOString(),
+      messageCount: cards.length,
+      agentStatus: latestAgent?.getAttribute("data-message-status") ?? null,
+      tracePresent: Boolean(trace),
+      traceStatus: trace?.getAttribute("data-status") ?? null,
+      traceOpen: details instanceof HTMLDetailsElement ? details.open : null,
+      rowCount: rows.length,
+      emptyLabel: empty?.textContent?.replace(/\s+/gu, " ").trim() ?? null,
+      latestRowPreview: latestRow?.textContent?.replace(/\s+/gu, " ").trim().slice(0, 240) ?? null,
+      finalTextChars: finalResponse?.textContent?.trim().length ?? 0
+    };
+  }, index);
 }
 
 async function waitForCommandReady(page, args, actions) {
@@ -930,6 +977,17 @@ function positiveInteger(value, label) {
   return parsed;
 }
 
+function nonNegativeInteger(value, label) {
+  const parsed = Number(value);
+  if (!Number.isInteger(parsed) || parsed < 0) throw new Error(`${label} must be a non-negative integer`);
+  return parsed;
+}
+
+function envNonNegativeInteger(name, fallback) {
+  const parsed = Number(process.env[name] ?? fallback);
+  return Number.isInteger(parsed) && parsed >= 0 ? parsed : fallback;
+}
+
 function processAlive(pid) {
   try {
     process.kill(pid, 0);
@@ -953,6 +1011,7 @@ function helpPayload() {
     usage: [
       "node scripts/web-live-dom-probe.mjs run --url http://74.48.78.17:19666/ --fresh-session --report /tmp/hwlab-dev-gate/web-live-dom-probe.json",
       "node scripts/web-live-dom-probe.mjs start --url http://74.48.78.17:19666/ --fresh-session --message '...' --no-cancel-running --wait-agent-terminal-ms 180000",
+      "node scripts/web-live-dom-probe.mjs run --url https://hwlab.pikapython.com/ --fresh-session --message '...' --no-cancel-running --trace-sample-count 6 --trace-sample-interval-ms 5000",
       "node scripts/web-live-dom-probe.mjs run --url http://74.48.78.17:19666/#/workspace --conversation-id cnv_...",
       "node scripts/web-live-dom-probe.mjs start --url http://74.48.78.17:19666/ --fresh-session",
       "node scripts/web-live-dom-probe.mjs status <jobId>"
diff --git a/web/hwlab-cloud-web/src/composables/useTraceSubscription.ts b/web/hwlab-cloud-web/src/composables/useTraceSubscription.ts
index 2d1b7360..4d0296bf 100644
--- a/web/hwlab-cloud-web/src/composables/useTraceSubscription.ts
+++ b/web/hwlab-cloud-web/src/composables/useTraceSubscription.ts
@@ -42,6 +42,8 @@ export interface TraceSubscriptionConfig {
 }
 
 const TRACE_POLL_INTERVAL_MS = 1500;
+const TRACE_LIVE_PAGE_LIMIT = 80;
+const TRACE_LIVE_MAX_PAGES_PER_POLL = 4;
 
 export function isTerminalStatus(status: string | undefined): boolean {
   if (!status) return false;
@@ -168,7 +170,7 @@ export async function subscribeToTrace(config: TraceSubscriptionConfig): Promise
   const { traceId, initial, onActivity, onSnapshot, onComplete, onInfrastructureError, signal, inactivityTimeoutMs, activityRef } = config;
   const projectId = normalizeWorkbenchProjectId(config.projectId) ?? DEFAULT_WORKBENCH_PROJECT_ID;
   if (isTerminalStatus(initial.status)) {
-    const snapshot = resultToTraceSnapshot(traceId, initial as AgentChatResultResponse);
+    const snapshot = resultToTraceSnapshot(traceId, initial as AgentChatResultResponse, "turn-api");
     onSnapshot(snapshot);
     onComplete(mergeTraceResults(initial as AgentChatResultResponse, snapshot));
     return;
@@ -178,8 +180,25 @@ export async function subscribeToTrace(config: TraceSubscriptionConfig): Promise
     return;
   }
 
-  let lastEventCount = -1;
-  let lastStatus: string | null = null;
+  let lastSnapshotKey = "";
+  let traceSinceSeq = 0;
+  let accumulatedTrace: TraceSnapshot | null = null;
+
+  const fetchLiveTracePages = async (): Promise<TraceSnapshot | null> => {
+    for (let page = 0; page < TRACE_LIVE_MAX_PAGES_PER_POLL; page += 1) {
+      const previousSinceSeq = traceSinceSeq;
+      const tracePolled = await agentAPI.getAgentTrace(traceId, projectId, inactivityTimeoutMs, activityRef, { sinceSeq: traceSinceSeq, limit: TRACE_LIVE_PAGE_LIMIT });
+      if (signal.aborted) return accumulatedTrace;
+      if (!tracePolled.ok || !tracePolled.data) return accumulatedTrace;
+      onActivity();
+      const pageSnapshot = resultToTraceSnapshot(traceId, tracePolled.data, "trace-api");
+      accumulatedTrace = mergeTraceSnapshots(accumulatedTrace, pageSnapshot);
+      const nextSinceSeq = traceSnapshotNextSinceSeq(pageSnapshot, traceSinceSeq);
+      if (nextSinceSeq > traceSinceSeq) traceSinceSeq = nextSinceSeq;
+      if (pageSnapshot.hasMore !== true || nextSinceSeq <= previousSinceSeq) break;
+    }
+    return accumulatedTrace;
+  };
 
   for (;;) {
     if (signal.aborted) return;
@@ -191,16 +210,17 @@ export async function subscribeToTrace(config: TraceSubscriptionConfig): Promise
 
     if (turnPolled.ok && turnPolled.data) {
       onActivity();
-      const snapshot = resultToTraceSnapshot(traceId, turnPolled.data);
-      const eventCount = snapshot.eventCount ?? snapshot.events?.length ?? 0;
-      const status = snapshot.status ?? "";
-      if (eventCount !== lastEventCount || status !== lastStatus) {
-        lastEventCount = eventCount;
-        lastStatus = status;
+      const turnSnapshot = resultToTraceSnapshot(traceId, turnPolled.data, "turn-api");
+      const liveTrace = await fetchLiveTracePages();
+      if (signal.aborted) return;
+      const snapshot = traceSnapshotWithTurnStatus(liveTrace ?? turnSnapshot, turnSnapshot);
+      const snapshotKey = traceSnapshotSignalKey(snapshot);
+      if (snapshotKey !== lastSnapshotKey) {
+        lastSnapshotKey = snapshotKey;
         onSnapshot(snapshot);
       }
       if (turnPolled.data.terminal === true || isTerminalStatus(turnPolled.data.status)) {
-        onComplete(mergeTraceResults(turnPolled.data, snapshot));
+        onComplete(mergeTraceResults(turnPolled.data, accumulatedTrace ?? snapshot));
         return;
       }
     } else if (!turnPolled.ok && turnPolled.status >= 500) {
@@ -212,7 +232,7 @@ export async function subscribeToTrace(config: TraceSubscriptionConfig): Promise
   }
 }
 
-function resultToTraceSnapshot(traceId: string, result: AgentChatResultResponse): TraceSnapshot {
+function resultToTraceSnapshot(traceId: string, result: AgentChatResultResponse, eventSource = "trace-api"): TraceSnapshot {
   const events = Array.isArray(result.events) ? result.events : Array.isArray(result.traceEvents) ? result.traceEvents : [];
   const lastEvent = events.at(-1);
   return {
@@ -236,11 +256,75 @@ function resultToTraceSnapshot(traceId: string, result: AgentChatResultResponse)
     traceSummary: result.traceSummary,
     error: result.error,
     lastEventLabel: result.lastEventLabel ?? lastEvent?.label ?? lastEvent?.type,
-    eventSource: "trace-api",
+    eventSource,
     updatedAt: new Date().toISOString()
   };
 }
 
+function mergeTraceSnapshots(previous: TraceSnapshot | null, next: TraceSnapshot): TraceSnapshot {
+  if (!previous) return next;
+  const previousEvents = Array.isArray(previous.events) ? previous.events : [];
+  const nextEvents = Array.isArray(next.events) ? next.events : [];
+  const events = mergeTraceEvents(previousEvents, nextEvents);
+  return {
+    ...previous,
+    ...next,
+    events,
+    eventCount: next.eventCount ?? previous.eventCount ?? events.length,
+    lastEventLabel: next.lastEventLabel ?? previous.lastEventLabel ?? events.at(-1)?.label ?? events.at(-1)?.type,
+    updatedAt: next.updatedAt ?? previous.updatedAt ?? new Date().toISOString()
+  };
+}
+
+function traceSnapshotWithTurnStatus(trace: TraceSnapshot, turn: TraceSnapshot): TraceSnapshot {
+  return {
+    ...trace,
+    traceId: trace.traceId ?? turn.traceId,
+    status: turn.status ?? trace.status,
+    sessionId: trace.sessionId ?? turn.sessionId,
+    threadId: trace.threadId ?? turn.threadId,
+    agentRun: trace.agentRun ?? turn.agentRun,
+    traceStatus: trace.traceStatus ?? turn.traceStatus,
+    terminalEvidence: trace.terminalEvidence ?? turn.terminalEvidence,
+    finalResponse: trace.finalResponse ?? turn.finalResponse,
+    traceSummary: trace.traceSummary ?? turn.traceSummary,
+    error: trace.error ?? turn.error,
+    waitingFor: trace.waitingFor ?? turn.waitingFor,
+    updatedAt: new Date().toISOString()
+  };
+}
+
+function traceSnapshotNextSinceSeq(snapshot: TraceSnapshot, fallback: number): number {
+  const direct = Number(snapshot.nextSinceSeq ?? snapshot.range?.toSeq);
+  if (Number.isFinite(direct) && direct >= 0) return Math.trunc(direct);
+  const events = Array.isArray(snapshot.events) ? snapshot.events : [];
+  return events.reduce((max, event) => {
+    const seq = Number(event.seq);
+    return Number.isFinite(seq) && seq > max ? Math.trunc(seq) : max;
+  }, fallback);
+}
+
+function traceSnapshotSignalKey(snapshot: TraceSnapshot): string {
+  const events = Array.isArray(snapshot.events) ? snapshot.events : [];
+  return [
+    snapshot.status ?? "",
+    snapshot.traceStatus ?? "",
+    snapshot.eventCount ?? events.length,
+    events.length,
+    snapshot.nextSinceSeq ?? snapshot.range?.toSeq ?? "",
+    snapshot.hasMore === true ? "more" : "caught-up",
+    snapshot.fullTraceLoaded === true ? "loaded" : "partial",
+    snapshot.lastEventLabel ?? events.at(-1)?.label ?? events.at(-1)?.type ?? "",
+    traceSnapshotErrorKey(snapshot.error)
+  ].join("|");
+}
+
+function traceSnapshotErrorKey(error: TraceSnapshot["error"]): string {
+  if (!error) return "";
+  if (typeof error === "string") return error;
+  return firstNonEmptyString(error.code, error.message) ?? "";
+}
+
 function sleep(ms: number): Promise<void> {
   return new Promise((resolve) => window.setTimeout(resolve, ms));
 }