diff --git a/src/resources/extensions/gsd/auto/finalize-timeout.ts b/src/resources/extensions/gsd/auto/finalize-timeout.ts
index dd457ac3b..f5e073fc9 100644
--- a/src/resources/extensions/gsd/auto/finalize-timeout.ts
+++ b/src/resources/extensions/gsd/auto/finalize-timeout.ts
@@ -7,6 +7,9 @@
  * Leaf module — no imports from auto/ to avoid circular dependencies.
  */
 
+/** Timeout for postUnitPreVerification in runFinalize (ms). */
+export const FINALIZE_PRE_TIMEOUT_MS = 60_000;
+
 /** Timeout for postUnitPostVerification in runFinalize (ms). */
 export const FINALIZE_POST_TIMEOUT_MS = 60_000;
 
diff --git a/src/resources/extensions/gsd/auto/loop.ts b/src/resources/extensions/gsd/auto/loop.ts
index 0a4d47960..7c9dd3650 100644
--- a/src/resources/extensions/gsd/auto/loop.ts
+++ b/src/resources/extensions/gsd/auto/loop.ts
@@ -46,7 +46,7 @@ export async function autoLoop(
 ): Promise<void> {
   debugLog("autoLoop", { phase: "enter" });
   let iteration = 0;
-  const loopState: LoopState = { recentUnits: [], stuckRecoveryAttempts: 0 };
+  const loopState: LoopState = { recentUnits: [], stuckRecoveryAttempts: 0, consecutiveFinalizeTimeouts: 0 };
   let consecutiveErrors = 0;
   const recentErrorMessages: string[] = [];
 
@@ -247,7 +247,7 @@ export async function autoLoop(
 
       // ── Phase 5: Finalize ───────────────────────────────────────────────
 
-      const finalizeResult = await runFinalize(ic, iterData, sidecarItem);
+      const finalizeResult = await runFinalize(ic, iterData, loopState, sidecarItem);
       if (finalizeResult.action === "break") break;
       if (finalizeResult.action === "continue") continue;
 
diff --git a/src/resources/extensions/gsd/auto/phases.ts b/src/resources/extensions/gsd/auto/phases.ts
index a5da2519c..8454602de 100644
--- a/src/resources/extensions/gsd/auto/phases.ts
+++ b/src/resources/extensions/gsd/auto/phases.ts
@@ -15,6 +15,7 @@ import type { PostUnitContext, PreVerificationOpts } from "../auto-post-unit.js"
 import {
   MAX_RECOVERY_CHARS,
   BUDGET_THRESHOLDS,
+  MAX_FINALIZE_TIMEOUTS,
   type PhaseResult,
   type IterationContext,
   type LoopState,
@@ -33,7 +34,7 @@ import { gsdRoot } from "../paths.js";
 import { atomicWriteSync } from "../atomic-write.js";
 import { verifyExpectedArtifact, diagnoseExpectedArtifact, buildLoopRemediationSteps } from "../auto-recovery.js";
 import { writeUnitRuntimeRecord } from "../unit-runtime.js";
-import { withTimeout, FINALIZE_POST_TIMEOUT_MS } from "./finalize-timeout.js";
+import { withTimeout, FINALIZE_PRE_TIMEOUT_MS, FINALIZE_POST_TIMEOUT_MS } from "./finalize-timeout.js";
 import { getEligibleSlices } from "../slice-parallel-eligibility.js";
 import { startSliceParallel } from "../slice-parallel-orchestrator.js";
 import { isDbAvailable, getMilestoneSlices } from "../gsd-db.js";
@@ -1427,6 +1428,7 @@ export async function runUnitPhase(
 export async function runFinalize(
   ic: IterationContext,
   iterData: IterationData,
+  loopState: LoopState,
   sidecarItem?: SidecarItem,
 ): Promise<PhaseResult> {
   const { ctx, pi, s, deps } = ic;
@@ -1450,13 +1452,58 @@ export async function runFinalize(
   };
 
   // Pre-verification processing (commit, doctor, state rebuild, etc.)
+  // Timeout guard: if postUnitPreVerification hangs (e.g., safety harness
+  // deadlock, browser teardown hang, worktree sync stall), force-continue
+  // after timeout so the auto-loop is not permanently frozen (#3757).
+  //
+  // On timeout, null out s.currentUnit so the timed-out task's late async
+  // mutations are harmless — postUnitPreVerification guards all side effects
+  // behind `if (s.currentUnit)`. The next iteration sets a fresh currentUnit.
   // Sidecar items use lightweight pre-verification opts
   const preVerificationOpts: PreVerificationOpts | undefined = sidecarItem
     ? sidecarItem.kind === "hook"
       ? { skipSettleDelay: true, skipWorktreeSync: true }
       : { skipSettleDelay: true }
     : undefined;
-  const preResult = await deps.postUnitPreVerification(postUnitCtx, preVerificationOpts);
+  const preUnitSnapshot = s.currentUnit
+    ? { type: s.currentUnit.type, id: s.currentUnit.id, startedAt: s.currentUnit.startedAt }
+    : null;
+  const preResultGuard = await withTimeout(
+    deps.postUnitPreVerification(postUnitCtx, preVerificationOpts),
+    FINALIZE_PRE_TIMEOUT_MS,
+    "postUnitPreVerification",
+  );
+
+  if (preResultGuard.timedOut) {
+    // Detach session from the timed-out unit so late async completions
+    // cannot mutate state for the next unit (#3757).
+    s.currentUnit = null;
+    loopState.consecutiveFinalizeTimeouts++;
+    debugLog("autoLoop", {
+      phase: "pre-verification-timeout",
+      iteration: ic.iteration,
+      unitType: iterData.unitType,
+      unitId: iterData.unitId,
+      consecutiveTimeouts: loopState.consecutiveFinalizeTimeouts,
+    });
+
+    if (loopState.consecutiveFinalizeTimeouts >= MAX_FINALIZE_TIMEOUTS) {
+      ctx.ui.notify(
+        `postUnitPreVerification timed out ${loopState.consecutiveFinalizeTimeouts} consecutive times — stopping auto-mode to prevent budget waste`,
+        "error",
+      );
+      await deps.stopAuto(ctx, pi, `${loopState.consecutiveFinalizeTimeouts} consecutive finalize timeouts`);
+      return { action: "break", reason: "finalize-timeout-escalation" };
+    }
+
+    ctx.ui.notify(
+      `postUnitPreVerification timed out after ${FINALIZE_PRE_TIMEOUT_MS / 1000}s for ${iterData.unitType} ${iterData.unitId} (${loopState.consecutiveFinalizeTimeouts}/${MAX_FINALIZE_TIMEOUTS}) — continuing to next iteration`,
+      "warning",
+    );
+    return { action: "next", data: undefined as void };
+  }
+
+  const preResult = preResultGuard.value;
   if (preResult === "dispatched") {
     debugLog("autoLoop", {
       phase: "exit",
@@ -1525,14 +1572,29 @@ export async function runFinalize(
   );
 
   if (postResultGuard.timedOut) {
+    // Detach session from the timed-out unit so late async completions
+    // cannot mutate state for the next unit (#3757).
+    s.currentUnit = null;
+    loopState.consecutiveFinalizeTimeouts++;
     debugLog("autoLoop", {
       phase: "post-verification-timeout",
       iteration: ic.iteration,
       unitType: iterData.unitType,
       unitId: iterData.unitId,
+      consecutiveTimeouts: loopState.consecutiveFinalizeTimeouts,
     });
+
+    if (loopState.consecutiveFinalizeTimeouts >= MAX_FINALIZE_TIMEOUTS) {
+      ctx.ui.notify(
+        `postUnitPostVerification timed out ${loopState.consecutiveFinalizeTimeouts} consecutive times — stopping auto-mode to prevent budget waste`,
+        "error",
+      );
+      await deps.stopAuto(ctx, pi, `${loopState.consecutiveFinalizeTimeouts} consecutive finalize timeouts`);
+      return { action: "break", reason: "finalize-timeout-escalation" };
+    }
+
     ctx.ui.notify(
-      `postUnitPostVerification timed out after ${FINALIZE_POST_TIMEOUT_MS / 1000}s for ${iterData.unitType} ${iterData.unitId} — continuing to next iteration`,
+      `postUnitPostVerification timed out after ${FINALIZE_POST_TIMEOUT_MS / 1000}s for ${iterData.unitType} ${iterData.unitId} (${loopState.consecutiveFinalizeTimeouts}/${MAX_FINALIZE_TIMEOUTS}) — continuing to next iteration`,
       "warning",
     );
     return { action: "next", data: undefined as void };
@@ -1554,6 +1616,9 @@ export async function runFinalize(
     return { action: "break", reason: "step-wizard" };
   }
 
+  // Both pre and post verification completed without timeout — reset counter
+  loopState.consecutiveFinalizeTimeouts = 0;
+
   return { action: "next", data: undefined as void };
 }
 
diff --git a/src/resources/extensions/gsd/auto/types.ts b/src/resources/extensions/gsd/auto/types.ts
index d3e342f82..9c2d1d466 100644
--- a/src/resources/extensions/gsd/auto/types.ts
+++ b/src/resources/extensions/gsd/auto/types.ts
@@ -91,8 +91,13 @@ export interface IterationContext {
 export interface LoopState {
   recentUnits: Array<{ key: string; error?: string }>;
   stuckRecoveryAttempts: number;
+  /** Consecutive finalize timeout count — stops auto-mode after threshold. */
+  consecutiveFinalizeTimeouts: number;
 }
 
+/** Max consecutive finalize timeouts before hard-stopping auto-mode. */
+export const MAX_FINALIZE_TIMEOUTS = 3;
+
 export interface PreDispatchData {
   state: GSDState;
   mid: string;
diff --git a/src/resources/extensions/gsd/tests/finalize-timeout-guard.test.ts b/src/resources/extensions/gsd/tests/finalize-timeout-guard.test.ts
index 2f212e4e4..d4eae33c1 100644
--- a/src/resources/extensions/gsd/tests/finalize-timeout-guard.test.ts
+++ b/src/resources/extensions/gsd/tests/finalize-timeout-guard.test.ts
@@ -19,8 +19,10 @@
 import { createTestContext } from "./test-helpers.ts";
 import {
   withTimeout,
+  FINALIZE_PRE_TIMEOUT_MS,
   FINALIZE_POST_TIMEOUT_MS,
 } from "../auto/finalize-timeout.ts";
+import { MAX_FINALIZE_TIMEOUTS } from "../auto/types.ts";
 
 const { assertTrue, assertEq, report } = createTestContext();
 
@@ -78,6 +80,25 @@ const { assertTrue, assertEq, report } = createTestContext();
   assertTrue(caught, "rejection should propagate");
 }
 
+// ═══ Test: FINALIZE_PRE_TIMEOUT_MS is defined and reasonable ═════════════════
+
+{
+  console.log("\n=== #3757: pre-verification timeout constant is defined and reasonable ===");
+
+  assertTrue(
+    typeof FINALIZE_PRE_TIMEOUT_MS === "number",
+    "FINALIZE_PRE_TIMEOUT_MS should be a number",
+  );
+  assertTrue(
+    FINALIZE_PRE_TIMEOUT_MS >= 30_000,
+    `pre timeout should be >= 30s (got ${FINALIZE_PRE_TIMEOUT_MS}ms)`,
+  );
+  assertTrue(
+    FINALIZE_PRE_TIMEOUT_MS <= 120_000,
+    `pre timeout should be <= 120s (got ${FINALIZE_PRE_TIMEOUT_MS}ms)`,
+  );
+}
+
 // ═══ Test: FINALIZE_POST_TIMEOUT_MS is defined and reasonable ═════════════════
 
 {
@@ -113,4 +134,108 @@ const { assertTrue, assertEq, report } = createTestContext();
   assertEq(result.timedOut, false, "should not time out");
 }
 
+// ═══ Test: runFinalize wraps BOTH pre and post verification with withTimeout ═
+
+{
+  console.log("\n=== #3757: runFinalize wraps preVerification with timeout guard ===");
+
+  const { readFileSync } = await import("node:fs");
+  const phasesSource = readFileSync(
+    new URL("../auto/phases.ts", import.meta.url),
+    "utf-8",
+  );
+
+  // Find the runFinalize function body
+  const fnIdx = phasesSource.indexOf("export async function runFinalize(");
+  assertTrue(fnIdx > 0, "runFinalize function should exist in phases.ts");
+
+  const fnBody = phasesSource.slice(fnIdx, fnIdx + 8000);
+
+  // postUnitPreVerification must be wrapped in withTimeout
+  const preTimeoutIdx = fnBody.indexOf("withTimeout(");
+  assertTrue(preTimeoutIdx > 0, "withTimeout should appear in runFinalize");
+
+  const preVerIdx = fnBody.indexOf("postUnitPreVerification");
+  assertTrue(preVerIdx > 0, "postUnitPreVerification should appear in runFinalize");
+
+  // The first withTimeout should wrap postUnitPreVerification (not postUnitPostVerification)
+  const firstWithTimeout = fnBody.slice(preTimeoutIdx, preTimeoutIdx + 200);
+  assertTrue(
+    firstWithTimeout.includes("postUnitPreVerification"),
+    "first withTimeout in runFinalize should wrap postUnitPreVerification",
+  );
+
+  // postUnitPostVerification must also be wrapped
+  const postVerIdx = fnBody.indexOf("postUnitPostVerification");
+  assertTrue(postVerIdx > 0, "postUnitPostVerification should appear in runFinalize");
+
+  // Count withTimeout occurrences — should be at least 2 (pre + post)
+  const timeoutCount = (fnBody.match(/withTimeout\(/g) || []).length;
+  assertTrue(
+    timeoutCount >= 2,
+    `runFinalize should have at least 2 withTimeout guards (found ${timeoutCount})`,
+  );
+}
+
+// ═══ Test: MAX_FINALIZE_TIMEOUTS is defined and reasonable ═══════════════════
+
+{
+  console.log("\n=== #3757: MAX_FINALIZE_TIMEOUTS is defined and reasonable ===");
+
+  assertTrue(
+    typeof MAX_FINALIZE_TIMEOUTS === "number",
+    "MAX_FINALIZE_TIMEOUTS should be a number",
+  );
+  assertTrue(
+    MAX_FINALIZE_TIMEOUTS >= 2,
+    `threshold should be >= 2 (got ${MAX_FINALIZE_TIMEOUTS})`,
+  );
+  assertTrue(
+    MAX_FINALIZE_TIMEOUTS <= 10,
+    `threshold should be <= 10 (got ${MAX_FINALIZE_TIMEOUTS})`,
+  );
+}
+
+// ═══ Test: timeout handlers escalate after consecutive timeouts ══════════════
+
+{
+  console.log("\n=== #3757: timeout handlers escalate and detach currentUnit ===");
+
+  const { readFileSync } = await import("node:fs");
+  const phasesSource = readFileSync(
+    new URL("../auto/phases.ts", import.meta.url),
+    "utf-8",
+  );
+
+  const fnIdx = phasesSource.indexOf("export async function runFinalize(");
+  const fnBody = phasesSource.slice(fnIdx, fnIdx + 8000);
+
+  // Both timeout handlers should increment consecutiveFinalizeTimeouts
+  const incrementCount = (fnBody.match(/consecutiveFinalizeTimeouts\+\+/g) || []).length;
+  assertTrue(
+    incrementCount >= 2,
+    `should increment consecutiveFinalizeTimeouts in both pre and post handlers (found ${incrementCount})`,
+  );
+
+  // Both timeout handlers should check MAX_FINALIZE_TIMEOUTS for escalation
+  const escalationCount = (fnBody.match(/MAX_FINALIZE_TIMEOUTS/g) || []).length;
+  assertTrue(
+    escalationCount >= 2,
+    `should check MAX_FINALIZE_TIMEOUTS in both handlers (found ${escalationCount})`,
+  );
+
+  // Both timeout handlers should null out s.currentUnit to prevent late mutations
+  const detachCount = (fnBody.match(/s\.currentUnit\s*=\s*null/g) || []).length;
+  assertTrue(
+    detachCount >= 2,
+    `should detach s.currentUnit in both timeout handlers (found ${detachCount})`,
+  );
+
+  // Successful finalize should reset the counter
+  assertTrue(
+    fnBody.includes("consecutiveFinalizeTimeouts = 0"),
+    "should reset consecutiveFinalizeTimeouts on successful finalize",
+  );
+}
+
 report();
diff --git a/src/resources/extensions/gsd/tests/journal-integration.test.ts b/src/resources/extensions/gsd/tests/journal-integration.test.ts
index 846982e26..8c946b96c 100644
--- a/src/resources/extensions/gsd/tests/journal-integration.test.ts
+++ b/src/resources/extensions/gsd/tests/journal-integration.test.ts
@@ -216,7 +216,7 @@ test("runDispatch emits dispatch-match with correct rule and flowId", async () =
     mid: "M001",
     midTitle: "Test Milestone",
   };
-  const loopState: LoopState = { recentUnits: [], stuckRecoveryAttempts: 0 };
+  const loopState: LoopState = { recentUnits: [], stuckRecoveryAttempts: 0, consecutiveFinalizeTimeouts: 0 };
 
   const result = await runDispatch(ic, preData, loopState);
 
@@ -248,7 +248,7 @@ test("runDispatch emits dispatch-stop when dispatch returns stop action", async
     mid: "M001",
     midTitle: "Test",
   };
-  const loopState: LoopState = { recentUnits: [], stuckRecoveryAttempts: 0 };
+  const loopState: LoopState = { recentUnits: [], stuckRecoveryAttempts: 0, consecutiveFinalizeTimeouts: 0 };
 
   const result = await runDispatch(ic, preData, loopState);
   assert.equal(result.action, "break");
@@ -303,6 +303,7 @@ test("runDispatch checks prior-slice completion against the project root in work
   const result = await runDispatch(ic, preData, {
     recentUnits: [],
     stuckRecoveryAttempts: 0,
+    consecutiveFinalizeTimeouts: 0,
   });
 
   assert.equal(result.action, "next");
@@ -343,7 +344,7 @@ test("runUnitPhase emits unit-start and unit-end with causedBy reference", async
     isRetry: false,
     previousTier: undefined,
   };
-  const loopState: LoopState = { recentUnits: [{ key: "execute-task/M001/S01/T01" }], stuckRecoveryAttempts: 0 };
+  const loopState: LoopState = { recentUnits: [{ key: "execute-task/M001/S01/T01" }], stuckRecoveryAttempts: 0, consecutiveFinalizeTimeouts: 0 };
 
   // Start runUnitPhase (it will block on runUnit internally)
   const unitPromise = runUnitPhase(ic, iterData, loopState);
@@ -400,7 +401,7 @@ test("all events from a mock iteration have monotonically increasing seq and sam
     mid: "M001",
     midTitle: "Test",
   };
-  const loopState: LoopState = { recentUnits: [], stuckRecoveryAttempts: 0 };
+  const loopState: LoopState = { recentUnits: [], stuckRecoveryAttempts: 0, consecutiveFinalizeTimeouts: 0 };
   const dispatchResult = await runDispatch(ic, preData, loopState);
   assert.equal(dispatchResult.action, "next");
 
@@ -446,7 +447,7 @@ test("dispatch-match events include matchedRule field matching the rule name", a
     midTitle: "Test",
   };
 
-  await runDispatch(ic, preData, { recentUnits: [], stuckRecoveryAttempts: 0 });
+  await runDispatch(ic, preData, { recentUnits: [], stuckRecoveryAttempts: 0, consecutiveFinalizeTimeouts: 0 });
 
   const matchEvents = capture.events.filter(e => e.eventType === "dispatch-match");
   assert.equal(matchEvents.length, 1);
@@ -475,7 +476,7 @@ test("pre-dispatch-hook event is emitted when hooks fire", async () => {
     midTitle: "Test",
   };
 
-  await runDispatch(ic, preData, { recentUnits: [], stuckRecoveryAttempts: 0 });
+  await runDispatch(ic, preData, { recentUnits: [], stuckRecoveryAttempts: 0, consecutiveFinalizeTimeouts: 0 });
 
   const hookEvents = capture.events.filter(e => e.eventType === "pre-dispatch-hook");
   assert.equal(hookEvents.length, 1, "should emit one pre-dispatch-hook event");
@@ -497,7 +498,7 @@ test("terminal event is emitted on milestone-complete", async () => {
     }) as any,
   });
   const ic = makeIC(deps);
-  const loopState: LoopState = { recentUnits: [], stuckRecoveryAttempts: 0 };
+  const loopState: LoopState = { recentUnits: [], stuckRecoveryAttempts: 0, consecutiveFinalizeTimeouts: 0 };
 
   const result = await runPreDispatch(ic, loopState);
   assert.equal(result.action, "break");
@@ -521,7 +522,7 @@ test("terminal event is emitted on blocked state", async () => {
     }) as any,
   });
   const ic = makeIC(deps);
-  const loopState: LoopState = { recentUnits: [], stuckRecoveryAttempts: 0 };
+  const loopState: LoopState = { recentUnits: [], stuckRecoveryAttempts: 0, consecutiveFinalizeTimeouts: 0 };
 
   const result = await runPreDispatch(ic, loopState);
   assert.equal(result.action, "break");
@@ -550,7 +551,7 @@ test("milestone-transition event is emitted when milestone changes", async () =>
   const ic = makeIC(deps);
   // Session says current milestone is M001, but state will return M002
   ic.s.currentMilestoneId = "M001";
-  const loopState: LoopState = { recentUnits: [], stuckRecoveryAttempts: 0 };
+  const loopState: LoopState = { recentUnits: [], stuckRecoveryAttempts: 0, consecutiveFinalizeTimeouts: 0 };
 
   await runPreDispatch(ic, loopState);
 
@@ -580,7 +581,7 @@ test("unit-end event contains errorContext when unit is cancelled with structure
     isRetry: false,
     previousTier: undefined,
   };
-  const loopState: LoopState = { recentUnits: [{ key: "execute-task/M001/S01/T01" }], stuckRecoveryAttempts: 0 };
+  const loopState: LoopState = { recentUnits: [{ key: "execute-task/M001/S01/T01" }], stuckRecoveryAttempts: 0, consecutiveFinalizeTimeouts: 0 };
 
   const unitPromise = runUnitPhase(ic, iterData, loopState);
   await new Promise(r => setTimeout(r, 50));