diff --git a/server/src/__tests__/heartbeat-run-log.test.ts b/server/src/__tests__/heartbeat-run-log.test.ts
index 9eb6eda9c79..df0f9f3cfbb 100644
--- a/server/src/__tests__/heartbeat-run-log.test.ts
+++ b/server/src/__tests__/heartbeat-run-log.test.ts
@@ -1,5 +1,6 @@
 import { describe, expect, it } from "vitest";
-import { compactRunLogChunk } from "../services/heartbeat.js";
+import type { Db } from "@paperclipai/db";
+import { compactRunLogChunk, heartbeatService } from "../services/heartbeat.js";
 
 describe("compactRunLogChunk", () => {
   it("redacts inline base64 image data from structured log chunks", () => {
@@ -39,3 +40,24 @@ describe("compactRunLogChunk", () => {
     expect(compacted).not.toContain("paperclip-flag-secret");
   });
 });
+
+describe("heartbeat run log reads", () => {
+  it("returns a pending empty payload when an existing run has no initialized log yet", async () => {
+    const service = heartbeatService({} as Db);
+
+    await expect(
+      service.readLog({
+        id: "run-pending-log",
+        companyId: "company-1",
+        logStore: null,
+        logRef: null,
+      }),
+    ).resolves.toEqual({
+      runId: "run-pending-log",
+      store: null,
+      logRef: null,
+      content: "",
+      pending: true,
+    });
+  });
+});
diff --git a/server/src/services/heartbeat.ts b/server/src/services/heartbeat.ts
index 09a1e5fe7cb..b18f8b9f9f4 100644
--- a/server/src/services/heartbeat.ts
+++ b/server/src/services/heartbeat.ts
@@ -10116,7 +10116,15 @@ export function heartbeatService(db: Db, options: HeartbeatServiceOptions = {})
       const run = typeof runOrLookup === "string" ? await getRunLogAccess(runOrLookup) : runOrLookup;
       const runId = typeof runOrLookup === "string" ? runOrLookup : runOrLookup.id;
       if (!run) throw notFound("Heartbeat run not found");
-      if (!run.logStore || !run.logRef) throw notFound("Run log not found");
+      if (!run.logStore || !run.logRef) {
+        return {
+          runId,
+          store: run.logStore,
+          logRef: run.logRef,
+          content: "",
+          pending: true,
+        };
+      }
 
       const result = await runLogStore.read(
         {
diff --git a/ui/src/api/heartbeats.ts b/ui/src/api/heartbeats.ts
index fbaad815d7e..0f4c4f0c361 100644
--- a/ui/src/api/heartbeats.ts
+++ b/ui/src/api/heartbeats.ts
@@ -84,7 +84,7 @@ export const heartbeatsApi = {
       `/heartbeat-runs/${runId}/events?afterSeq=${encodeURIComponent(String(afterSeq))}&limit=${encodeURIComponent(String(limit))}`,
     ),
   log: (runId: string, offset = 0, limitBytes = 256000) =>
-    api.get<{ runId: string; store: string; logRef: string; content: string; nextOffset?: number }>(
+    api.get<{ runId: string; store: string | null; logRef: string | null; content: string; nextOffset?: number; pending?: boolean }>(
       `/heartbeat-runs/${runId}/log?offset=${encodeURIComponent(String(offset))}&limitBytes=${encodeURIComponent(String(limitBytes))}`,
     ),
   workspaceOperations: (runId: string) =>
diff --git a/ui/src/components/transcript/useLiveRunTranscripts.test.tsx b/ui/src/components/transcript/useLiveRunTranscripts.test.tsx
index 025d2f0ed0c..2422b1586e7 100644
--- a/ui/src/components/transcript/useLiveRunTranscripts.test.tsx
+++ b/ui/src/components/transcript/useLiveRunTranscripts.test.tsx
@@ -81,6 +81,7 @@ describe("useLiveRunTranscripts", () => {
   });
 
   afterEach(() => {
+    vi.useRealTimers();
     globalThis.WebSocket = OriginalWebSocket;
   });
 
@@ -229,6 +230,44 @@ describe("useLiveRunTranscripts", () => {
     container.remove();
   });
 
+  it("stops polling active runs after a persisted-log 404", async () => {
+    vi.useFakeTimers();
+    logMock.mockReset();
+    logMock.mockRejectedValue(new ApiError("Run log not found", 404, { error: "Run log not found" }));
+
+    function Harness() {
+      useLiveRunTranscripts({
+        companyId: "company-1",
+        runs: [{ id: "run-stale", status: "running", adapterType: "codex_local" }],
+        logPollIntervalMs: 10,
+      });
+      return null;
+    }
+
+    const container = document.createElement("div");
+    document.body.appendChild(container);
+    const root = createRoot(container);
+
+    await act(async () => {
+      root.render(<Harness />);
+      await Promise.resolve();
+    });
+
+    expect(logMock).toHaveBeenCalledTimes(1);
+
+    await act(async () => {
+      vi.advanceTimersByTime(30);
+      await Promise.resolve();
+    });
+
+    expect(logMock).toHaveBeenCalledTimes(1);
+
+    act(() => {
+      root.unmount();
+    });
+    container.remove();
+  });
+
   it("can hydrate active runs without opening the live event socket", async () => {
     function Harness() {
       useLiveRunTranscripts({
diff --git a/ui/src/components/transcript/useLiveRunTranscripts.ts b/ui/src/components/transcript/useLiveRunTranscripts.ts
index 6c001e2fae4..a19f76a7099 100644
--- a/ui/src/components/transcript/useLiveRunTranscripts.ts
+++ b/ui/src/components/transcript/useLiveRunTranscripts.ts
@@ -113,7 +113,7 @@ export function useLiveRunTranscripts({
   const seenChunkKeysRef = useRef(new Set<string>());
   const pendingLogRowsByRunRef = useRef(new Map<string, string>());
   const logOffsetByRunRef = useRef(new Map<string, number>());
-  const missingTerminalLogRunIdsRef = useRef(new Set<string>());
+  const missingLogRunIdsRef = useRef(new Set<string>());
   const transcriptCacheRef = useRef(new Map<string, {
     adapterType: string;
     chunks: RunLogChunk[];
@@ -196,9 +196,9 @@ export function useLiveRunTranscripts({
         logOffsetByRunRef.current.delete(runId);
       }
     }
-    for (const runId of missingTerminalLogRunIdsRef.current.keys()) {
+    for (const runId of missingLogRunIdsRef.current.keys()) {
       if (!knownRunIds.has(runId)) {
-        missingTerminalLogRunIdsRef.current.delete(runId);
+        missingLogRunIdsRef.current.delete(runId);
       }
     }
     for (const runId of transcriptCacheRef.current.keys()) {
@@ -214,7 +214,7 @@ export function useLiveRunTranscripts({
     let cancelled = false;
 
     const readRunLog = async (run: RunTranscriptSource) => {
-      if (missingTerminalLogRunIdsRef.current.has(run.id)) {
+      if (missingLogRunIdsRef.current.has(run.id)) {
         return;
       }
       const offset = logOffsetByRunRef.current.get(run.id) ?? resolveInitialLogOffset(run, logReadLimitBytes);
@@ -232,8 +232,8 @@ export function useLiveRunTranscripts({
           logOffsetByRunRef.current.set(run.id, offset + result.content.length);
         }
       } catch (error) {
-        if (error instanceof ApiError && error.status === 404 && isTerminalStatus(run.status)) {
-          missingTerminalLogRunIdsRef.current.add(run.id);
+        if (error instanceof ApiError && error.status === 404) {
+          missingLogRunIdsRef.current.add(run.id);
         }
       } finally {
         if (!cancelled) {