diff --git a/ui/src/pages/AgentDetail.progress.test.ts b/ui/src/pages/AgentDetail.progress.test.ts
new file mode 100644
index 0000000000..03c62e3722
--- /dev/null
+++ b/ui/src/pages/AgentDetail.progress.test.ts
@@ -0,0 +1,61 @@
+import { describe, expect, it } from "vitest";
+
+import {
+  buildHeartbeatProgressLogLine,
+  heartbeatProgressLogLineKey,
+} from "./AgentDetail";
+
+describe("buildHeartbeatProgressLogLine", () => {
+  it("renders progress messages with phase prefixes as system log lines", () => {
+    expect(
+      buildHeartbeatProgressLogLine(
+        {
+          message: "Syncing issue history",
+          phase: "workspace",
+          updatedAt: "2026-07-04T05:00:00.000Z",
+        },
+        "2026-07-04T04:59:00.000Z",
+      ),
+    ).toEqual({
+      ts: "2026-07-04T05:00:00.000Z",
+      stream: "system",
+      chunk: "[workspace] Syncing issue history",
+    });
+  });
+
+  it("renders progress messages without phases using the live event timestamp", () => {
+    expect(
+      buildHeartbeatProgressLogLine(
+        { message: "Preparing workspace" },
+        "2026-07-04T05:01:00.000Z",
+      ),
+    ).toEqual({
+      ts: "2026-07-04T05:01:00.000Z",
+      stream: "system",
+      chunk: "Preparing workspace",
+    });
+  });
+
+  it("ignores empty progress messages", () => {
+    expect(
+      buildHeartbeatProgressLogLine(
+        { message: "   ", phase: "workspace" },
+        "2026-07-04T05:02:00.000Z",
+      ),
+    ).toBeNull();
+  });
+});
+
+describe("heartbeatProgressLogLineKey", () => {
+  it("uses the rendered log line fields as the replay key", () => {
+    const line = {
+      ts: "2026-07-04T05:03:00.000Z",
+      stream: "system" as const,
+      chunk: "[workspace] Syncing issue history",
+    };
+
+    expect(heartbeatProgressLogLineKey(line)).toBe(
+      "2026-07-04T05:03:00.000Z\u0000system\u0000[workspace] Syncing issue history",
+    );
+  });
+});
diff --git a/ui/src/pages/AgentDetail.tsx b/ui/src/pages/AgentDetail.tsx
index d591392f3e..7ca04287f8 100644
--- a/ui/src/pages/AgentDetail.tsx
+++ b/ui/src/pages/AgentDetail.tsx
@@ -301,7 +301,11 @@ function runMetrics(run: HeartbeatRun) {
   };
 }
 
-type RunLogChunk = { ts: string; stream: "stdout" | "stderr" | "system"; chunk: string };
+export type RunLogChunk = {
+  ts: string;
+  stream: "stdout" | "stderr" | "system";
+  chunk: string;
+};
 
 function asRecord(value: unknown): Record<string, unknown> | null {
   if (typeof value !== "object" || value === null || Array.isArray(value)) return null;
@@ -314,6 +318,22 @@ function asNonEmptyString(value: unknown): string | null {
   return trimmed.length > 0 ? trimmed : null;
 }
 
+export function buildHeartbeatProgressLogLine(
+  payload: Record<string, unknown>,
+  fallbackTimestamp: string,
+): RunLogChunk | null {
+  const message = asNonEmptyString(payload.message);
+  if (!message) return null;
+  const phase = asNonEmptyString(payload.phase);
+  const ts = asNonEmptyString(payload.updatedAt) ?? fallbackTimestamp;
+  const chunk = phase ? `[${phase}] ${message}` : message;
+  return { ts, stream: "system", chunk };
+}
+
+export function heartbeatProgressLogLineKey(line: RunLogChunk): string {
+  return `${line.ts}\u0000${line.stream}\u0000${line.chunk}`;
+}
+
 export function RunInvocationCard({
   payload,
   censorUsernameInLogs,
@@ -3591,6 +3611,7 @@ function LogViewer({ run, adapterType }: { run: HeartbeatRun; adapterType: strin
   const [transcriptMode, setTranscriptMode] = useState<TranscriptMode>("nice");
   const logEndRef = useRef<HTMLDivElement>(null);
   const pendingLogLineRef = useRef("");
+  const seenProgressLogLineKeysRef = useRef<Set<string>>(new Set());
   const scrollContainerRef = useRef<ScrollContainer | null>(null);
   const isFollowingRef = useRef(false);
   const lastMetricsRef = useRef<{ scrollHeight: number; distanceFromBottom: number }>({
@@ -3738,6 +3759,7 @@ function LogViewer({ run, adapterType }: { run: HeartbeatRun; adapterType: strin
   useEffect(() => {
     let cancelled = false;
     pendingLogLineRef.current = "";
+    seenProgressLogLineKeysRef.current = new Set();
     setLogLines([]);
     setLogOffset(0);
     setHasMoreLog(false);
@@ -3885,6 +3907,16 @@ function LogViewer({ run, adapterType }: { run: HeartbeatRun; adapterType: strin
           return;
         }
 
+        if (event.type === "heartbeat.run.progress") {
+          const line = buildHeartbeatProgressLogLine(payload, event.createdAt);
+          if (!line) return;
+          const key = heartbeatProgressLogLineKey(line);
+          if (seenProgressLogLineKeysRef.current.has(key)) return;
+          seenProgressLogLineKeysRef.current.add(key);
+          setLogLines((prev) => [...prev, line]);
+          return;
+        }
+
         if (event.type !== "heartbeat.run.event") return;
 
         const seq = typeof payload.seq === "number" ? payload.seq : null;