From d89b2438c300ea89490fff55f37c7bef07559cdf Mon Sep 17 00:00:00 2001
From: ephraimduncan <ephraimduncan68@gmail.com>
Date: Mon, 14 Sep 2026 18:04:46 +0000
Subject: [PATCH] fix(health): stop expired probes before work starts

---
 CHANGES.md                      |  5 +++++
 packages/health/src/run.test.ts | 21 +++++++++++++++++++++
 packages/health/src/run.ts      |  1 +
 3 files changed, 27 insertions(+)

diff --git a/CHANGES.md b/CHANGES.md
index 2099aa4..2ebed3a 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,5 +1,10 @@
 # Changelog
 
+## Unreleased
+
+- `@openstatus/health`: Probes no longer start work if an async `skip`
+  returns `false` after the timeout. The completed timeout report stays unchanged.
+
 ## 0.1.2
 
 - Every hosting package (`fly`, `koyeb`, `railway`, `vercel`, `cloudflare`)
diff --git a/packages/health/src/run.test.ts b/packages/health/src/run.test.ts
index e3d6f73..724cd5b 100644
--- a/packages/health/src/run.test.ts
+++ b/packages/health/src/run.test.ts
@@ -175,6 +175,27 @@ test("runProbes() times out a hanging skip()", async () => {
   assert.equal(report.checks[0].status, "timeout");
 });
 
+test("runProbes() does not start work when skip() resolves false after timeout", async () => {
+  const skip = Promise.withResolvers<boolean>();
+  let ran = false;
+  const report = await runProbes([{
+    name: "a",
+    timeoutMs: 10,
+    skip: () => skip.promise,
+    run: () => {
+      ran = true;
+    },
+  }]);
+  assert.equal(report.checks[0].status, "timeout");
+  const completed = structuredClone(report);
+
+  skip.resolve(false);
+  await delay(0);
+
+  assert.equal(ran, false);
+  assert.deepEqual(report, completed);
+});
+
 test("runProbes() passes name, critical and timeoutMs to run()", async () => {
   let seen: { name: string; critical: boolean; timeoutMs: number } | undefined;
   await runProbes([{
diff --git a/packages/health/src/run.ts b/packages/health/src/run.ts
index bae9a3a..0089ddf 100644
--- a/packages/health/src/run.ts
+++ b/packages/health/src/run.ts
@@ -63,6 +63,7 @@ async function runProbe(
 
   const work = Promise.resolve().then(async () => {
     if (await probe.skip?.()) return "skipped";
+    controller.signal.throwIfAborted();
     await probe.run(controller.signal, ctx);
     return "ok";
   });