diff --git a/server/src/routes/agents.ts b/server/src/routes/agents.ts
index 6c4973cd3dc..1724c3baf6e 100644
--- a/server/src/routes/agents.ts
+++ b/server/src/routes/agents.ts
@@ -2498,6 +2498,7 @@ export function agentRoutes(db: Db) {
       agentId: heartbeatRuns.agentId,
       agentName: agentsTable.name,
       adapterType: agentsTable.adapterType,
+      logBytes: heartbeatRuns.logBytes,
       livenessState: heartbeatRuns.livenessState,
       livenessReason: heartbeatRuns.livenessReason,
       continuationAttempt: heartbeatRuns.continuationAttempt,
@@ -2778,6 +2779,7 @@ export function agentRoutes(db: Db) {
         agentId: heartbeatRuns.agentId,
         agentName: agentsTable.name,
         adapterType: agentsTable.adapterType,
+        logBytes: heartbeatRuns.logBytes,
         livenessState: heartbeatRuns.livenessState,
         livenessReason: heartbeatRuns.livenessReason,
         continuationAttempt: heartbeatRuns.continuationAttempt,
diff --git a/server/src/services/heartbeat.ts b/server/src/services/heartbeat.ts
index 24813eb077b..a5e89836d1b 100644
--- a/server/src/services/heartbeat.ts
+++ b/server/src/services/heartbeat.ts
@@ -744,6 +744,7 @@ const heartbeatRunIssueSummaryColumns = {
   finishedAt: heartbeatRuns.finishedAt,
   createdAt: heartbeatRuns.createdAt,
   agentId: heartbeatRuns.agentId,
+  logBytes: heartbeatRuns.logBytes,
   processStartedAt: heartbeatRuns.processStartedAt,
   livenessState: heartbeatRuns.livenessState,
   livenessReason: heartbeatRuns.livenessReason,
diff --git a/ui/src/api/heartbeats.ts b/ui/src/api/heartbeats.ts
index 72c8e0a700b..ea7ae5d6ed2 100644
--- a/ui/src/api/heartbeats.ts
+++ b/ui/src/api/heartbeats.ts
@@ -20,6 +20,8 @@ export interface ActiveRunForIssue {
   agentId: string;
   agentName: string;
   adapterType: string;
+  logBytes?: number | null;
+  lastOutputBytes?: number | null;
   issueId?: string | null;
   livenessState?: RunLivenessFields["livenessState"];
   livenessReason?: string | null;
@@ -39,6 +41,8 @@ export interface LiveRunForIssue {
   agentId: string;
   agentName: string;
   adapterType: string;
+  logBytes?: number | null;
+  lastOutputBytes?: number | null;
   issueId?: string | null;
   livenessState?: RunLivenessFields["livenessState"];
   livenessReason?: string | null;
diff --git a/ui/src/components/IssueChatThread.tsx b/ui/src/components/IssueChatThread.tsx
index ea1d4d3aff0..746844ac544 100644
--- a/ui/src/components/IssueChatThread.tsx
+++ b/ui/src/components/IssueChatThread.tsx
@@ -2411,6 +2411,8 @@ export function IssueChatThread({
         agentId: activeRun.agentId,
         agentName: activeRun.agentName,
         adapterType: activeRun.adapterType,
+        logBytes: activeRun.logBytes,
+        lastOutputBytes: activeRun.lastOutputBytes,
       });
     }
     return [...deduped.values()].sort((a, b) => new Date(a.createdAt).getTime() - new Date(b.createdAt).getTime());
diff --git a/ui/src/components/LiveRunWidget.tsx b/ui/src/components/LiveRunWidget.tsx
index e9c2fe7bff9..26a5a3acd7f 100644
--- a/ui/src/components/LiveRunWidget.tsx
+++ b/ui/src/components/LiveRunWidget.tsx
@@ -59,6 +59,8 @@ export function LiveRunWidget({ issueId, companyId }: LiveRunWidgetProps) {
         agentId: activeRun.agentId,
         agentName: activeRun.agentName,
         adapterType: activeRun.adapterType,
+        logBytes: activeRun.logBytes,
+        lastOutputBytes: activeRun.lastOutputBytes,
         issueId,
       });
     }
diff --git a/ui/src/components/transcript/useLiveRunTranscripts.test.tsx b/ui/src/components/transcript/useLiveRunTranscripts.test.tsx
index 9fdb4794589..025d2f0ed0c 100644
--- a/ui/src/components/transcript/useLiveRunTranscripts.test.tsx
+++ b/ui/src/components/transcript/useLiveRunTranscripts.test.tsx
@@ -258,6 +258,34 @@ describe("useLiveRunTranscripts", () => {
     container.remove();
   });
 
+  it("starts persisted-log hydration from the newest bytes when the visible window is truncated", async () => {
+    function Harness() {
+      useLiveRunTranscripts({
+        companyId: "company-1",
+        runs: [{ id: "run-1", status: "running", adapterType: "codex_local", lastOutputBytes: 100_000 }],
+        enableRealtimeUpdates: false,
+        logReadLimitBytes: 64_000,
+      });
+      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).toHaveBeenCalledWith("run-1", 36_000, 64_000);
+
+    act(() => {
+      root.unmount();
+    });
+    container.remove();
+  });
+
   it("rebuilds only the transcript for the run that receives live output", async () => {
     function Harness() {
       useLiveRunTranscripts({
diff --git a/ui/src/components/transcript/useLiveRunTranscripts.ts b/ui/src/components/transcript/useLiveRunTranscripts.ts
index 991b9658486..74f94256d8e 100644
--- a/ui/src/components/transcript/useLiveRunTranscripts.ts
+++ b/ui/src/components/transcript/useLiveRunTranscripts.ts
@@ -16,6 +16,8 @@ export interface RunTranscriptSource {
   status: string;
   adapterType: string;
   hasStoredOutput?: boolean;
+  logBytes?: number | null;
+  lastOutputBytes?: number | null;
 }
 
 interface UseLiveRunTranscriptsOptions {
@@ -35,6 +37,19 @@ function isTerminalStatus(status: string): boolean {
   return status === "failed" || status === "timed_out" || status === "cancelled" || status === "succeeded";
 }
 
+function runKnownLogBytes(run: RunTranscriptSource): number | null {
+  const bytes = run.status === "queued"
+    ? run.logBytes
+    : run.lastOutputBytes ?? run.logBytes;
+  return typeof bytes === "number" && Number.isFinite(bytes) && bytes > 0 ? bytes : null;
+}
+
+export function resolveInitialLogOffset(run: RunTranscriptSource, limitBytes: number): number {
+  const knownBytes = runKnownLogBytes(run);
+  if (knownBytes === null) return 0;
+  return Math.max(0, knownBytes - Math.max(0, limitBytes));
+}
+
 function parsePersistedLogContent(
   runId: string,
   content: string,
@@ -82,7 +97,11 @@ export function useLiveRunTranscripts({
   const runsKey = useMemo(
     () =>
       runs
-        .map((run) => `${run.id}:${run.status}:${run.adapterType}:${run.hasStoredOutput === true ? "1" : "0"}`)
+        .map((run) => {
+          const logBytes = typeof run.logBytes === "number" ? run.logBytes : "";
+          const lastOutputBytes = typeof run.lastOutputBytes === "number" ? run.lastOutputBytes : "";
+          return `${run.id}:${run.status}:${run.adapterType}:${run.hasStoredOutput === true ? "1" : "0"}:${logBytes}:${lastOutputBytes}`;
+        })
         .sort((a, b) => a.localeCompare(b))
         .join(","),
     [runs],
@@ -197,7 +216,7 @@ export function useLiveRunTranscripts({
       if (missingTerminalLogRunIdsRef.current.has(run.id)) {
         return;
       }
-      const offset = logOffsetByRunRef.current.get(run.id) ?? 0;
+      const offset = logOffsetByRunRef.current.get(run.id) ?? resolveInitialLogOffset(run, logReadLimitBytes);
       try {
         const result = await heartbeatsApi.log(run.id, offset, logReadLimitBytes);
         if (cancelled) return;
diff --git a/ui/src/lib/issue-chat-messages.ts b/ui/src/lib/issue-chat-messages.ts
index b63d15a6650..aa2285d1447 100644
--- a/ui/src/lib/issue-chat-messages.ts
+++ b/ui/src/lib/issue-chat-messages.ts
@@ -43,6 +43,7 @@ export interface IssueChatLinkedRun {
   startedAt: Date | string | null;
   finishedAt?: Date | string | null;
   hasStoredOutput?: boolean;
+  logBytes?: number | null;
 }
 
 export interface IssueChatTranscriptEntry {
diff --git a/ui/src/lib/issueChatTranscriptRuns.ts b/ui/src/lib/issueChatTranscriptRuns.ts
index 1832e864817..a2b5c1e754a 100644
--- a/ui/src/lib/issueChatTranscriptRuns.ts
+++ b/ui/src/lib/issueChatTranscriptRuns.ts
@@ -15,6 +15,8 @@ export function resolveIssueChatTranscriptRuns(args: {
       id: run.id,
       status: run.status,
       adapterType: run.adapterType,
+      logBytes: run.logBytes,
+      lastOutputBytes: run.lastOutputBytes,
     });
   }
 
@@ -23,6 +25,8 @@ export function resolveIssueChatTranscriptRuns(args: {
       id: activeRun.id,
       status: activeRun.status,
       adapterType: activeRun.adapterType,
+      logBytes: activeRun.logBytes,
+      lastOutputBytes: activeRun.lastOutputBytes,
     });
   }
 
@@ -35,6 +39,7 @@ export function resolveIssueChatTranscriptRuns(args: {
       status: run.status,
       adapterType,
       hasStoredOutput: run.hasStoredOutput,
+      logBytes: run.logBytes,
     });
   }