diff --git a/src/config/schema.help.ts b/src/config/schema.help.ts
index 61eb12c6dc6..94f1766e487 100644
--- a/src/config/schema.help.ts
+++ b/src/config/schema.help.ts
@@ -418,6 +418,8 @@ export const FIELD_HELP: Record<string, string> = {
     'Enable targeted diagnostics logs by flag (e.g. ["telegram.http"]). Supports wildcards like "telegram.*" or "*".',
   "diagnostics.enabled":
     "Master toggle for diagnostics instrumentation output in logs and telemetry wiring paths. Keep enabled for normal observability, and disable only in tightly constrained environments.",
+  "diagnostics.stuckSessionWarnMs":
+    "Age threshold in milliseconds for emitting stuck-session warnings while a session remains in processing state. Increase for long multi-tool turns to reduce false positives; decrease for faster hang detection.",
   "diagnostics.otel.enabled":
     "Enables OpenTelemetry export pipeline for traces, metrics, and logs based on configured endpoint/protocol settings. Keep disabled unless your collector endpoint and auth are fully configured.",
   "diagnostics.otel.endpoint":
@@ -945,6 +947,8 @@ export const FIELD_HELP: Record<string, string> = {
     "Enables pre-compaction memory flush before the runtime performs stronger history reduction near token limits. Keep enabled unless you intentionally disable memory side effects in constrained environments.",
   "agents.defaults.compaction.memoryFlush.softThresholdTokens":
     "Threshold distance to compaction (in tokens) that triggers pre-compaction memory flush execution. Use earlier thresholds for safer persistence, or tighter thresholds for lower flush frequency.",
+  "agents.defaults.compaction.memoryFlush.forceFlushTranscriptBytes":
+    'Forces pre-compaction memory flush when transcript file size reaches this threshold (bytes or strings like "2mb"). Use this to prevent long-session hangs even when token counters are stale; set to 0 to disable.',
   "agents.defaults.compaction.memoryFlush.prompt":
     "User-prompt template used for the pre-compaction memory flush turn when generating memory candidates. Use this only when you need custom extraction instructions beyond the default memory flush behavior.",
   "agents.defaults.compaction.memoryFlush.systemPrompt":
diff --git a/src/config/schema.labels.ts b/src/config/schema.labels.ts
index d5a6170c330..de1bcbed3eb 100644
--- a/src/config/schema.labels.ts
+++ b/src/config/schema.labels.ts
@@ -34,6 +34,7 @@ export const FIELD_LABELS: Record<string, string> = {
   "update.auto.betaCheckIntervalHours": "Auto Update Beta Check Interval (hours)",
   "diagnostics.enabled": "Diagnostics Enabled",
   "diagnostics.flags": "Diagnostics Flags",
+  "diagnostics.stuckSessionWarnMs": "Stuck Session Warning Threshold (ms)",
   "diagnostics.otel.enabled": "OpenTelemetry Enabled",
   "diagnostics.otel.endpoint": "OpenTelemetry Endpoint",
   "diagnostics.otel.protocol": "OpenTelemetry Protocol",
@@ -421,6 +422,8 @@ export const FIELD_LABELS: Record<string, string> = {
   "agents.defaults.compaction.memoryFlush.enabled": "Compaction Memory Flush Enabled",
   "agents.defaults.compaction.memoryFlush.softThresholdTokens":
     "Compaction Memory Flush Soft Threshold",
+  "agents.defaults.compaction.memoryFlush.forceFlushTranscriptBytes":
+    "Compaction Memory Flush Transcript Size Threshold",
   "agents.defaults.compaction.memoryFlush.prompt": "Compaction Memory Flush Prompt",
   "agents.defaults.compaction.memoryFlush.systemPrompt": "Compaction Memory Flush System Prompt",
   "agents.defaults.embeddedPi": "Embedded Pi",
diff --git a/src/config/types.base.ts b/src/config/types.base.ts
index bcc3bf6b969..03336561d64 100644
--- a/src/config/types.base.ts
+++ b/src/config/types.base.ts
@@ -205,6 +205,8 @@ export type DiagnosticsConfig = {
   enabled?: boolean;
   /** Optional ad-hoc diagnostics flags (e.g. "telegram.http"). */
   flags?: string[];
+  /** Threshold in ms before a processing session logs "stuck session" diagnostics. */
+  stuckSessionWarnMs?: number;
   otel?: DiagnosticsOtelConfig;
   cacheTrace?: DiagnosticsCacheTraceConfig;
 };
diff --git a/src/config/zod-schema.ts b/src/config/zod-schema.ts
index 73677c8bf34..8034c5b5e42 100644
--- a/src/config/zod-schema.ts
+++ b/src/config/zod-schema.ts
@@ -179,6 +179,7 @@ export const OpenClawSchema = z
       .object({
         enabled: z.boolean().optional(),
         flags: z.array(z.string()).optional(),
+        stuckSessionWarnMs: z.number().int().positive().optional(),
         otel: z
           .object({
             enabled: z.boolean().optional(),
diff --git a/src/gateway/server.impl.ts b/src/gateway/server.impl.ts
index b3e6a9b3c15..4ae6016a46a 100644
--- a/src/gateway/server.impl.ts
+++ b/src/gateway/server.impl.ts
@@ -371,7 +371,7 @@ export async function startGatewayServer(
   ).config;
   const diagnosticsEnabled = isDiagnosticsEnabled(cfgAtStart);
   if (diagnosticsEnabled) {
-    startDiagnosticHeartbeat();
+    startDiagnosticHeartbeat(cfgAtStart);
   }
   setGatewaySigusr1RestartPolicy({ allowExternal: isRestartEnabled(cfgAtStart) });
   setPreRestartDeferralCheck(
diff --git a/src/logging/diagnostic.test.ts b/src/logging/diagnostic.test.ts
index 37eecaf0b12..45a57770c3f 100644
--- a/src/logging/diagnostic.test.ts
+++ b/src/logging/diagnostic.test.ts
@@ -1,5 +1,6 @@
 import fs from "node:fs";
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { onDiagnosticEvent, resetDiagnosticEventsForTest } from "../infra/diagnostic-events.js";
 import {
   diagnosticSessionStates,
   getDiagnosticSessionStateCountForTest,
@@ -7,6 +8,12 @@ import {
   pruneDiagnosticSessionStates,
   resetDiagnosticSessionStateForTest,
 } from "./diagnostic-session-state.js";
+import {
+  logSessionStateChange,
+  resetDiagnosticStateForTest,
+  resolveStuckSessionWarnMs,
+  startDiagnosticHeartbeat,
+} from "./diagnostic.js";
 
 describe("diagnostic session state pruning", () => {
   beforeEach(() => {
@@ -74,3 +81,60 @@ describe("logger import side effects", () => {
     expect(mkdirSpy).not.toHaveBeenCalled();
   });
 });
+
+describe("stuck session diagnostics threshold", () => {
+  beforeEach(() => {
+    vi.useFakeTimers();
+    resetDiagnosticStateForTest();
+    resetDiagnosticEventsForTest();
+  });
+
+  afterEach(() => {
+    resetDiagnosticEventsForTest();
+    resetDiagnosticStateForTest();
+    vi.useRealTimers();
+  });
+
+  it("uses the configured diagnostics.stuckSessionWarnMs threshold", () => {
+    const events: Array<{ type: string }> = [];
+    const unsubscribe = onDiagnosticEvent((event) => {
+      events.push({ type: event.type });
+    });
+    try {
+      startDiagnosticHeartbeat({
+        diagnostics: {
+          enabled: true,
+          stuckSessionWarnMs: 30_000,
+        },
+      });
+      logSessionStateChange({ sessionId: "s1", sessionKey: "main", state: "processing" });
+      vi.advanceTimersByTime(61_000);
+    } finally {
+      unsubscribe();
+    }
+
+    expect(events.filter((event) => event.type === "session.stuck")).toHaveLength(1);
+  });
+
+  it("falls back to default threshold when config is absent", () => {
+    const events: Array<{ type: string }> = [];
+    const unsubscribe = onDiagnosticEvent((event) => {
+      events.push({ type: event.type });
+    });
+    try {
+      startDiagnosticHeartbeat();
+      logSessionStateChange({ sessionId: "s2", sessionKey: "main", state: "processing" });
+      vi.advanceTimersByTime(31_000);
+    } finally {
+      unsubscribe();
+    }
+
+    expect(events.filter((event) => event.type === "session.stuck")).toHaveLength(0);
+  });
+
+  it("uses default threshold for invalid values", () => {
+    expect(resolveStuckSessionWarnMs({ diagnostics: { stuckSessionWarnMs: -1 } })).toBe(120_000);
+    expect(resolveStuckSessionWarnMs({ diagnostics: { stuckSessionWarnMs: 0 } })).toBe(120_000);
+    expect(resolveStuckSessionWarnMs()).toBe(120_000);
+  });
+});
diff --git a/src/logging/diagnostic.ts b/src/logging/diagnostic.ts
index 3751416c13a..ffc36cf98ee 100644
--- a/src/logging/diagnostic.ts
+++ b/src/logging/diagnostic.ts
@@ -1,3 +1,4 @@
+import type { OpenClawConfig } from "../config/config.js";
 import { emitDiagnosticEvent } from "../infra/diagnostic-events.js";
 import {
   diagnosticSessionStates,
@@ -20,11 +21,26 @@ const webhookStats = {
 };
 
 let lastActivityAt = 0;
+const DEFAULT_STUCK_SESSION_WARN_MS = 120_000;
+const MIN_STUCK_SESSION_WARN_MS = 1_000;
+const MAX_STUCK_SESSION_WARN_MS = 24 * 60 * 60 * 1000;
 
 function markActivity() {
   lastActivityAt = Date.now();
 }
 
+export function resolveStuckSessionWarnMs(config?: OpenClawConfig): number {
+  const raw = config?.diagnostics?.stuckSessionWarnMs;
+  if (typeof raw !== "number" || !Number.isFinite(raw)) {
+    return DEFAULT_STUCK_SESSION_WARN_MS;
+  }
+  const rounded = Math.floor(raw);
+  if (rounded < MIN_STUCK_SESSION_WARN_MS || rounded > MAX_STUCK_SESSION_WARN_MS) {
+    return DEFAULT_STUCK_SESSION_WARN_MS;
+  }
+  return rounded;
+}
+
 export function logWebhookReceived(params: {
   channel: string;
   updateType?: string;
@@ -305,10 +321,11 @@ export function logActiveRuns() {
 
 let heartbeatInterval: NodeJS.Timeout | null = null;
 
-export function startDiagnosticHeartbeat() {
+export function startDiagnosticHeartbeat(config?: OpenClawConfig) {
   if (heartbeatInterval) {
     return;
   }
+  const stuckSessionWarnMs = resolveStuckSessionWarnMs(config);
   heartbeatInterval = setInterval(() => {
     const now = Date.now();
     pruneDiagnosticSessionStates(now, true);
@@ -362,7 +379,7 @@ export function startDiagnosticHeartbeat() {
 
     for (const [, state] of diagnosticSessionStates) {
       const ageMs = now - state.lastActivity;
-      if (state.state === "processing" && ageMs > 120_000) {
+      if (state.state === "processing" && ageMs > stuckSessionWarnMs) {
         logSessionStuck({
           sessionId: state.sessionId,
           sessionKey: state.sessionKey,
diff --git a/src/telegram/webhook.ts b/src/telegram/webhook.ts
index a55720102dd..8333a6a1ebe 100644
--- a/src/telegram/webhook.ts
+++ b/src/telegram/webhook.ts
@@ -120,7 +120,7 @@ export async function startTelegramWebhook(opts: {
   });
 
   if (diagnosticsEnabled) {
-    startDiagnosticHeartbeat();
+    startDiagnosticHeartbeat(opts.config);
   }
 
   const server = createServer((req, res) => {