From b0c8a8c827b46fba95f0946e06a06ff61b284596 Mon Sep 17 00:00:00 2001
From: Kit Langton <kit.langton@gmail.com>
Date: Fri, 28 Aug 2026 17:18:32 -0400
Subject: [PATCH] fix(util): refresh flock heartbeat time (#45720)

---
 packages/core/test/util/effect-flock.test.ts | 23 ++++++++++++++++++++
 packages/util/src/effect-flock.ts            | 15 +++++++------
 2 files changed, 31 insertions(+), 7 deletions(-)

diff --git a/packages/core/test/util/effect-flock.test.ts b/packages/core/test/util/effect-flock.test.ts
index 2813a623218..4af0445c8c3 100644
--- a/packages/core/test/util/effect-flock.test.ts
+++ b/packages/core/test/util/effect-flock.test.ts
@@ -156,6 +156,29 @@ describe("util.effect-flock", () => {
     }),
   )
 
+  it.live(
+    "advances the heartbeat timestamp while the lock is held",
+    Effect.gen(function* () {
+      const flock = yield* EffectFlock.Service
+      const tmp = yield* Effect.promise(() => fs.mkdtemp(path.join(os.tmpdir(), "eflock-test-")))
+      const dir = path.join(tmp, "locks")
+      const heartbeat = path.join(lock(dir, "eflock:heartbeat"), "heartbeat")
+      yield* Effect.addFinalizer(() => Effect.promise(() => fs.rm(tmp, { recursive: true, force: true })))
+
+      yield* Effect.scoped(
+        Effect.gen(function* () {
+          yield* flock.acquire("eflock:heartbeat", dir, { staleMs: 300 })
+          yield* Effect.sleep(150)
+          const first = yield* Effect.promise(() => fs.stat(heartbeat))
+          yield* Effect.sleep(250)
+          const second = yield* Effect.promise(() => fs.stat(heartbeat))
+
+          expect(second.mtimeMs).toBeGreaterThan(first.mtimeMs)
+        }),
+      )
+    }),
+  )
+
   it.live(
     "breaks stale lock dirs",
     Effect.gen(function* () {
diff --git a/packages/util/src/effect-flock.ts b/packages/util/src/effect-flock.ts
index 788fd81d0d5..d35b685ca62 100644
--- a/packages/util/src/effect-flock.ts
+++ b/packages/util/src/effect-flock.ts
@@ -284,13 +284,14 @@ export namespace EffectFlock {
         )
 
         // Heartbeat fiber — scoped, so it's interrupted before release runs
-        yield* fs
-          .utimes(handle.heartbeatPath, new Date(), new Date())
-          .pipe(
-            Effect.ignore,
-            Effect.repeat(Schedule.spaced(Math.max(100, Math.floor(staleMs / 3)))),
-            Effect.forkScoped,
-          )
+        yield* Effect.suspend(() => {
+          const now = new Date()
+          return fs.utimes(handle.heartbeatPath, now, now)
+        }).pipe(
+          Effect.ignore,
+          Effect.repeat(Schedule.spaced(Math.max(100, Math.floor(staleMs / 3)))),
+          Effect.forkScoped,
+        )
       })
 
       const withLock: Interface["withLock"] = Function.dual(