feat(FN-4885): complete Step 1 — core deadlock threshold primitives

Fusion-Task-Id: FN-4885
Fusion-Task-Lineage: 31110eed-5ca3-4d67-8f11-581185056dc6

packages/core/src/__tests__/in-review-stall.test.ts

@@ -1,5 +1,6 @@
 import { describe, expect, it } from "vitest";
 import {
+  countRecentIdenticalStallEntries,
   DEFAULT_MAX_AUTO_MERGE_RETRIES,
   DEFAULT_STALE_MERGING_MIN_AGE_MS,
   getInReviewStallReason,
@@ -21,6 +22,48 @@ const baseTask = {
   updatedAt: new Date(NOW).toISOString(),
 };
 
+describe("countRecentIdenticalStallEntries", () => {
+  const reason = "Failed to create worktree after 3 attempts";
+  const task = (log: Array<{ timestamp: string; action: string }>) => ({ log });
+
+  it("returns 0 with no log entries", () => {
+    expect(countRecentIdenticalStallEntries(task([]), { code: "merge-blocker", reason })).toBe(0);
+  });
+
+  it("counts three identical most-recent entries", () => {
+    expect(countRecentIdenticalStallEntries(task([
+      { timestamp: "2026-05-12T11:57:00.000Z", action: `In-review stall surfaced [merge-blocker]: ${reason}` },
+      { timestamp: "2026-05-12T11:58:00.000Z", action: `In-review stall surfaced [merge-blocker]: ${reason}` },
+      { timestamp: "2026-05-12T11:59:00.000Z", action: `In-review stall surfaced [merge-blocker]: ${reason}` },
+    ]), { code: "merge-blocker", reason })).toBe(3);
+  });
+
+  it("stops at first non-stall entry and only counts the suffix", () => {
+    expect(countRecentIdenticalStallEntries(task([
+      { timestamp: "2026-05-12T11:56:00.000Z", action: `In-review stall surfaced [merge-blocker]: ${reason}` },
+      { timestamp: "2026-05-12T11:57:00.000Z", action: "something else" },
+      { timestamp: "2026-05-12T11:58:00.000Z", action: `In-review stall surfaced [merge-blocker]: ${reason}` },
+      { timestamp: "2026-05-12T11:59:00.000Z", action: `In-review stall surfaced [merge-blocker]: ${reason}` },
+    ]), { code: "merge-blocker", reason })).toBe(2);
+  });
+
+  it("stops counting on different code", () => {
+    expect(countRecentIdenticalStallEntries(task([
+      { timestamp: "2026-05-12T11:57:00.000Z", action: "In-review stall surfaced [merge-retries-exhausted]: retries exhausted" },
+      { timestamp: "2026-05-12T11:58:00.000Z", action: `In-review stall surfaced [merge-blocker]: ${reason}` },
+      { timestamp: "2026-05-12T11:59:00.000Z", action: `In-review stall surfaced [merge-blocker]: ${reason}` },
+    ]), { code: "merge-blocker", reason })).toBe(2);
+  });
+
+  it("stops counting on different reason text", () => {
+    expect(countRecentIdenticalStallEntries(task([
+      { timestamp: "2026-05-12T11:57:00.000Z", action: "In-review stall surfaced [merge-blocker]: another reason" },
+      { timestamp: "2026-05-12T11:58:00.000Z", action: `In-review stall surfaced [merge-blocker]: ${reason}` },
+      { timestamp: "2026-05-12T11:59:00.000Z", action: `In-review stall surfaced [merge-blocker]: ${reason}` },
+    ]), { code: "merge-blocker", reason })).toBe(2);
+  });
+});
+
 describe("getInReviewStallReason", () => {
   it("returns transient-merge-status-no-owner for FN-4110 fixture", () => {
     const signal = getInReviewStallReason(

packages/core/src/in-review-stall.ts

@@ -1,5 +1,5 @@
 import { getTaskMergeBlocker } from "./task-merge.js";
-import type { Task } from "./types.js";
+import type { Task, TaskLogEntry } from "./types.js";
 
 /**
  * State-based in-review stall detection. This is complementary to FN-4168's
@@ -32,9 +32,39 @@ export interface InReviewStallContext {
 export const DEFAULT_STALE_MERGING_MIN_AGE_MS = 5 * 60_000;
 /** Keep aligned with engine MAX_AUTO_MERGE_RETRIES (core must not import engine). */
 export const DEFAULT_MAX_AUTO_MERGE_RETRIES = 3;
+export const IN_REVIEW_STALL_LOG_PREFIX = "In-review stall surfaced [";
+export const IN_REVIEW_STALL_DEADLOCK_LOG_PREFIX = "In-review stall auto-disposed [";
 
 const TRANSIENT_MERGE_STATUSES = new Set(["merging", "merging-pr", "merging-fix"]);
 
+export function countRecentIdenticalStallEntries(
+  task: Pick<Task, "log">,
+  signal: Pick<InReviewStallSignal, "code" | "reason">,
+): number {
+  const trimmedReason = signal.reason.trim();
+  const reversed = [...(task.log ?? [])].reverse();
+  let count = 0;
+
+  for (const entry of reversed) {
+    if (!entry.action.startsWith(IN_REVIEW_STALL_LOG_PREFIX)) {
+      break;
+    }
+    if (!matchesStallEntry(entry, signal.code, trimmedReason)) {
+      break;
+    }
+    count += 1;
+  }
+
+  return count;
+}
+
+function matchesStallEntry(entry: TaskLogEntry, code: InReviewStallCode, reason: string): boolean {
+  const prefix = `${IN_REVIEW_STALL_LOG_PREFIX}${code}]:`;
+  if (!entry.action.startsWith(prefix)) return false;
+  const rawReason = entry.action.slice(prefix.length).trim();
+  return rawReason === reason;
+}
+
 export function getInReviewStallReason(
   task: Pick<Task, "column" | "paused" | "status" | "error" | "steps" | "workflowStepResults" | "worktree" | "mergeDetails" | "mergeRetries" | "updatedAt"> & { id?: string },
   context: InReviewStallContext = {},

packages/core/src/settings-schema.ts

@@ -267,6 +267,7 @@ export const DEFAULT_PROJECT_SETTINGS = {
   specStalenessEnabled: false,
   specStalenessMaxAgeMs: 6 * 60 * 60 * 1000,
   taskStuckTimeoutMs: 600_000,
+  inReviewStallDeadlockThreshold: 3,
   stalePausedReviewThresholdMs: 24 * 60 * 60_000,
   // Capacity risk warning default: only warn once todo is meaningfully backlogged.
   capacityRiskBannerEnabled: false,

packages/core/src/types.ts

@@ -2851,6 +2851,10 @@ export interface ProjectSettings {
    *  than this duration, the task is considered stuck and will be terminated and retried.
    *  Default: 600000 (10 minutes). Set to 0 to disable. */
   taskStuckTimeoutMs?: number;
+  /** Minimum number of identical consecutive in-review stall log entries (same code + reason)
+   *  before the task is auto-disposed with `pausedReason='in-review-stall-deadlock'`.
+   *  Default: 3. Set to 0 to disable. */
+  inReviewStallDeadlockThreshold?: number;
   /** Threshold in milliseconds for surfacing paused in-review tasks as stale.
    *  Age is measured from columnMovedAt when present, otherwise updatedAt.
    *  Default: 86400000 (24 hours). Set to 0 or undefined to disable surfacing. */