fix(agent): prevent session lock deadlock on timeout during compaction (#9855)

Merged via /review-pr -> /prepare-pr -> /merge-pr.

Prepared head SHA: 64a28900f1
Co-authored-by: mverrilli <816450+mverrilli@users.noreply.github.com>
Co-authored-by: gumadeiras <5599352+gumadeiras@users.noreply.github.com>
Reviewed-by: @gumadeiras

src/agents/pi-embedded-runner/run.overflow-compaction.e2e.test.ts

@@ -206,6 +206,7 @@ function makeAttemptResult(
   return {
     aborted: false,
     timedOut: false,
+    timedOutDuringCompaction: false,
     promptError: null,
     sessionIdUsed: "test-session",
     assistantTexts: ["Hello!"],

src/agents/pi-embedded-runner/run.ts

@@ -480,7 +480,14 @@ export async function runEmbeddedPiAgent(
             enforceFinalTag: params.enforceFinalTag,
           });
 
-          const { aborted, promptError, timedOut, sessionIdUsed, lastAssistant } = attempt;
+          const {
+            aborted,
+            promptError,
+            timedOut,
+            timedOutDuringCompaction,
+            sessionIdUsed,
+            lastAssistant,
+          } = attempt;
           const lastAssistantUsage = normalizeUsage(lastAssistant?.usage as UsageLike);
           const attemptUsage = attempt.attemptUsage ?? lastAssistantUsage;
           mergeUsageIntoAccumulator(usageAccumulator, attemptUsage);
@@ -801,7 +808,9 @@ export async function runEmbeddedPiAgent(
           }
 
           // Treat timeout as potential rate limit (Antigravity hangs on rate limit)
-          const shouldRotate = (!aborted && failoverFailure) || timedOut;
+          // But exclude post-prompt compaction timeouts (model succeeded; no profile issue)
+          const shouldRotate =
+            (!aborted && failoverFailure) || (timedOut && !timedOutDuringCompaction);
 
           if (shouldRotate) {
             if (lastProfileId) {

src/agents/pi-embedded-runner/run/attempt.ts

@@ -91,6 +91,10 @@ import {
 import { splitSdkTools } from "../tool-split.js";
 import { describeUnknownError, mapThinkingLevel } from "../utils.js";
 import { flushPendingToolResultsAfterIdle } from "../wait-for-idle-before-flush.js";
+import {
+  selectCompactionTimeoutSnapshot,
+  shouldFlagCompactionTimeout,
+} from "./compaction-timeout.js";
 import { detectAndLoadPromptImages } from "./images.js";
 
 export function injectHistoryImagesIntoMessages(
@@ -665,6 +669,7 @@ export async function runEmbeddedAttempt(
 
       let aborted = Boolean(params.abortSignal?.aborted);
       let timedOut = false;
+      let timedOutDuringCompaction = false;
       const getAbortReason = (signal: AbortSignal): unknown =>
         "reason" in signal ? (signal as { reason?: unknown }).reason : undefined;
       const makeTimeoutAbortReason = (): Error => {
@@ -769,6 +774,15 @@ export async function runEmbeddedAttempt(
               `embedded run timeout: runId=${params.runId} sessionId=${params.sessionId} timeoutMs=${params.timeoutMs}`,
             );
           }
+          if (
+            shouldFlagCompactionTimeout({
+              isTimeout: true,
+              isCompactionPendingOrRetrying: subscription.isCompacting(),
+              isCompactionInFlight: activeSession.isCompacting,
+            })
+          ) {
+            timedOutDuringCompaction = true;
+          }
           abortRun(true);
           if (!abortWarnTimer) {
             abortWarnTimer = setTimeout(() => {
@@ -791,6 +805,15 @@ export async function runEmbeddedAttempt(
       const onAbort = () => {
         const reason = params.abortSignal ? getAbortReason(params.abortSignal) : undefined;
         const timeout = reason ? isTimeoutError(reason) : false;
+        if (
+          shouldFlagCompactionTimeout({
+            isTimeout: timeout,
+            isCompactionPendingOrRetrying: subscription.isCompacting(),
+            isCompactionInFlight: activeSession.isCompacting,
+          })
+        ) {
+          timedOutDuringCompaction = true;
+        }
         abortRun(timeout, reason);
       };
       if (params.abortSignal) {
@@ -939,13 +962,28 @@ export async function runEmbeddedAttempt(
           );
         }
 
+        // Capture snapshot before compaction wait so we have complete messages if timeout occurs
+        // Check compaction state before and after to avoid race condition where compaction starts during capture
+        // Use session state (not subscription) for snapshot decisions - need instantaneous compaction status
+        const wasCompactingBefore = activeSession.isCompacting;
+        const snapshot = activeSession.messages.slice();
+        const wasCompactingAfter = activeSession.isCompacting;
+        // Only trust snapshot if compaction wasn't running before or after capture
+        const preCompactionSnapshot = wasCompactingBefore || wasCompactingAfter ? null : snapshot;
+        const preCompactionSessionId = activeSession.sessionId;
+
         try {
-          await waitForCompactionRetry();
+          await abortable(waitForCompactionRetry());
         } catch (err) {
           if (isRunnerAbortError(err)) {
             if (!promptError) {
               promptError = err;
             }
+            if (!isProbeSession) {
+              log.debug(
+                `compaction wait aborted: runId=${params.runId} sessionId=${params.sessionId}`,
+              );
+            }
           } else {
             throw err;
           }
@@ -956,27 +994,51 @@ export async function runEmbeddedAttempt(
         // inserted between compaction and the next prompt — breaking the
         // prepareCompaction() guard that checks the last entry type, leading to
         // double-compaction. See: https://github.com/openclaw/openclaw/issues/9282
-        const shouldTrackCacheTtl =
-          params.config?.agents?.defaults?.contextPruning?.mode === "cache-ttl" &&
-          isCacheTtlEligibleProvider(params.provider, params.modelId);
-        if (shouldTrackCacheTtl) {
-          appendCacheTtlTimestamp(sessionManager, {
-            timestamp: Date.now(),
-            provider: params.provider,
-            modelId: params.modelId,
-          });
+        // Skip when timed out during compaction — session state may be inconsistent.
+        if (!timedOutDuringCompaction) {
+          const shouldTrackCacheTtl =
+            params.config?.agents?.defaults?.contextPruning?.mode === "cache-ttl" &&
+            isCacheTtlEligibleProvider(params.provider, params.modelId);
+          if (shouldTrackCacheTtl) {
+            appendCacheTtlTimestamp(sessionManager, {
+              timestamp: Date.now(),
+              provider: params.provider,
+              modelId: params.modelId,
+            });
+          }
         }
 
-        messagesSnapshot = activeSession.messages.slice();
-        sessionIdUsed = activeSession.sessionId;
+        // If timeout occurred during compaction, use pre-compaction snapshot when available
+        // (compaction restructures messages but does not add user/assistant turns).
+        const snapshotSelection = selectCompactionTimeoutSnapshot({
+          timedOutDuringCompaction,
+          preCompactionSnapshot,
+          preCompactionSessionId,
+          currentSnapshot: activeSession.messages.slice(),
+          currentSessionId: activeSession.sessionId,
+        });
+        if (timedOutDuringCompaction) {
+          if (!isProbeSession) {
+            log.warn(
+              `using ${snapshotSelection.source} snapshot: timed out during compaction runId=${params.runId} sessionId=${params.sessionId}`,
+            );
+          }
+        }
+        messagesSnapshot = snapshotSelection.messagesSnapshot;
+        sessionIdUsed = snapshotSelection.sessionIdUsed;
         cacheTrace?.recordStage("session:after", {
           messages: messagesSnapshot,
-          note: promptError ? "prompt error" : undefined,
+          note: timedOutDuringCompaction
+            ? "compaction timeout"
+            : promptError
+              ? "prompt error"
+              : undefined,
         });
         anthropicPayloadLogger?.recordUsage(messagesSnapshot, promptError);
 
         // Run agent_end hooks to allow plugins to analyze the conversation
         // This is fire-and-forget, so we don't await
+        // Run even on compaction timeout so plugins can log/cleanup
         if (hookRunner?.hasHooks("agent_end")) {
           hookRunner
             .runAgentEnd(
@@ -1003,7 +1065,21 @@ export async function runEmbeddedAttempt(
         if (abortWarnTimer) {
           clearTimeout(abortWarnTimer);
         }
-        unsubscribe();
+        if (!isProbeSession && (aborted || timedOut) && !timedOutDuringCompaction) {
+          log.debug(
+            `run cleanup: runId=${params.runId} sessionId=${params.sessionId} aborted=${aborted} timedOut=${timedOut}`,
+          );
+        }
+        try {
+          unsubscribe();
+        } catch (err) {
+          // unsubscribe() should never throw; if it does, it indicates a serious bug.
+          // Log at error level to ensure visibility, but don't rethrow in finally block
+          // as it would mask any exception from the try block above.
+          log.error(
+            `CRITICAL: unsubscribe failed, possible resource leak: runId=${params.runId} ${String(err)}`,
+          );
+        }
         clearActiveEmbeddedRun(params.sessionId, queueHandle);
         params.abortSignal?.removeEventListener?.("abort", onAbort);
       }
@@ -1023,6 +1099,7 @@ export async function runEmbeddedAttempt(
       return {
         aborted,
         timedOut,
+        timedOutDuringCompaction,
         promptError,
         sessionIdUsed,
         systemPromptReport,

src/agents/pi-embedded-runner/run/compaction-timeout.e2e.test.ts

@@ -0,0 +1,61 @@
+import { describe, expect, it } from "vitest";
+import {
+  selectCompactionTimeoutSnapshot,
+  shouldFlagCompactionTimeout,
+} from "./compaction-timeout.js";
+
+describe("compaction-timeout helpers", () => {
+  it("flags compaction timeout consistently for internal and external timeout sources", () => {
+    const internalTimer = shouldFlagCompactionTimeout({
+      isTimeout: true,
+      isCompactionPendingOrRetrying: true,
+      isCompactionInFlight: false,
+    });
+    const externalAbort = shouldFlagCompactionTimeout({
+      isTimeout: true,
+      isCompactionPendingOrRetrying: true,
+      isCompactionInFlight: false,
+    });
+    expect(internalTimer).toBe(true);
+    expect(externalAbort).toBe(true);
+  });
+
+  it("does not flag when timeout is false", () => {
+    expect(
+      shouldFlagCompactionTimeout({
+        isTimeout: false,
+        isCompactionPendingOrRetrying: true,
+        isCompactionInFlight: true,
+      }),
+    ).toBe(false);
+  });
+
+  it("uses pre-compaction snapshot when compaction timeout occurs", () => {
+    const pre = [{ role: "assistant", content: "pre" }] as const;
+    const current = [{ role: "assistant", content: "current" }] as const;
+    const selected = selectCompactionTimeoutSnapshot({
+      timedOutDuringCompaction: true,
+      preCompactionSnapshot: [...pre],
+      preCompactionSessionId: "session-pre",
+      currentSnapshot: [...current],
+      currentSessionId: "session-current",
+    });
+    expect(selected.source).toBe("pre-compaction");
+    expect(selected.sessionIdUsed).toBe("session-pre");
+    expect(selected.messagesSnapshot).toEqual(pre);
+  });
+
+  it("falls back to current snapshot when pre-compaction snapshot is unavailable", () => {
+    const current = [{ role: "assistant", content: "current" }] as const;
+    const selected = selectCompactionTimeoutSnapshot({
+      timedOutDuringCompaction: true,
+      preCompactionSnapshot: null,
+      preCompactionSessionId: "session-pre",
+      currentSnapshot: [...current],
+      currentSessionId: "session-current",
+    });
+    expect(selected.source).toBe("current");
+    expect(selected.sessionIdUsed).toBe("session-current");
+    expect(selected.messagesSnapshot).toEqual(current);
+  });
+});

src/agents/pi-embedded-runner/run/compaction-timeout.ts

@@ -0,0 +1,54 @@
+import type { AgentMessage } from "@mariozechner/pi-agent-core";
+
+export type CompactionTimeoutSignal = {
+  isTimeout: boolean;
+  isCompactionPendingOrRetrying: boolean;
+  isCompactionInFlight: boolean;
+};
+
+export function shouldFlagCompactionTimeout(signal: CompactionTimeoutSignal): boolean {
+  if (!signal.isTimeout) {
+    return false;
+  }
+  return signal.isCompactionPendingOrRetrying || signal.isCompactionInFlight;
+}
+
+export type SnapshotSelectionParams = {
+  timedOutDuringCompaction: boolean;
+  preCompactionSnapshot: AgentMessage[] | null;
+  preCompactionSessionId: string;
+  currentSnapshot: AgentMessage[];
+  currentSessionId: string;
+};
+
+export type SnapshotSelection = {
+  messagesSnapshot: AgentMessage[];
+  sessionIdUsed: string;
+  source: "pre-compaction" | "current";
+};
+
+export function selectCompactionTimeoutSnapshot(
+  params: SnapshotSelectionParams,
+): SnapshotSelection {
+  if (!params.timedOutDuringCompaction) {
+    return {
+      messagesSnapshot: params.currentSnapshot,
+      sessionIdUsed: params.currentSessionId,
+      source: "current",
+    };
+  }
+
+  if (params.preCompactionSnapshot) {
+    return {
+      messagesSnapshot: params.preCompactionSnapshot,
+      sessionIdUsed: params.preCompactionSessionId,
+      source: "pre-compaction",
+    };
+  }
+
+  return {
+    messagesSnapshot: params.currentSnapshot,
+    sessionIdUsed: params.currentSessionId,
+    source: "current",
+  };
+}

src/agents/pi-embedded-runner/run/types.ts

@@ -24,6 +24,8 @@ export type EmbeddedRunAttemptParams = EmbeddedRunAttemptBase & {
 export type EmbeddedRunAttemptResult = {
   aborted: boolean;
   timedOut: boolean;
+  /** True if the timeout occurred while compaction was in progress or pending. */
+  timedOutDuringCompaction: boolean;
   promptError: unknown;
   sessionIdUsed: string;
   systemPromptReport?: SessionSystemPromptReport;