From 02fca8a6248c2898025748f41c9bf5252094fd9e Mon Sep 17 00:00:00 2001
From: clover caruso <git@paperclover.net>
Date: Fri, 11 Sep 2026 10:33:40 -0700
Subject: [PATCH] fix: clear pending delay on fast mutation failures

A failure within the 200ms pending delay notified "mutating" a second time,
which replaced pendingTimer without clearing the first timer. That orphaned
timer later set isPending after the mutation had gone idle, leaving it stuck.

Assisted-by: claude-opus-5
---
 jsr.json                |  2 +-
 readme.changes.md       |  7 +++++++
 src/react.ts            |  2 +-
 test/useMutate.test.tsx | 42 +++++++++++++++++++++++++++++++++++++++++
 4 files changed, 51 insertions(+), 2 deletions(-)

diff --git a/jsr.json b/jsr.json
index 97ae6d43d77e074576a9e0ace43b10140e01d3db..05e8a948095e5526ba7bece4ecd4acd718427b8e 100644
--- a/jsr.json
+++ b/jsr.json
@@ -1,6 +1,6 @@
 {
   "name": "@clo/react-mutation",
-  "version": "3.0.1",
+  "version": "3.0.2",
   "exports": {
     ".": "./src/mod.ts",
     "./tanstack-query": "./src/tanstack-query.ts",
diff --git a/readme.changes.md b/readme.changes.md
index ce2fc98aa8bdcbe92eea3ef6959ba760555c3ddd..c5d4f1975073539f89e1b8e503c849977150e8fe 100644
--- a/readme.changes.md
+++ b/readme.changes.md
@@ -1,5 +1,12 @@
 # notable changes in React Mutation
 
+## v3.0.2
+
+### bugfixes
+
+- resolve `useMutate` leaving `isPending` stuck `true` when a mutation fails
+  within the 200ms pending delay
+
 ## v3.0.1
 
 ### bugfixes
diff --git a/src/react.ts b/src/react.ts
index 36a7b629b846909aac6b47adc3d582d466309285..156ccc5c7f873024525bfbccc02404183e9f11a8 100644
--- a/src/react.ts
+++ b/src/react.ts
@@ -305,7 +305,7 @@ class Observer<Args extends unknown[], Result> {
           });
 
           if (!this.state.isPending && this.state.isMutating && !debounced) {
-            this.pendingTimer = setTimeout(() => {
+            this.pendingTimer ??= setTimeout(() => {
               this.pendingTimer = null;
               this.setState({ isPending: true });
             }, 200);
diff --git a/test/useMutate.test.tsx b/test/useMutate.test.tsx
index a880a2b68a4a8e58b1e514f022d37792b35d48dd..bfa833b2bc7399ea70e2ae20a1ba443ba22ade52 100644
--- a/test/useMutate.test.tsx
+++ b/test/useMutate.test.tsx
@@ -94,6 +94,48 @@ test("useMutate - global error and success handling", async () => {
   ]);
 });
 
+test("useMutate - a failure before the pending delay never leaves isPending stuck", async () => {
+  vi.useFakeTimers({ shouldAdvanceTime: true });
+  const user = userEvent.setup({ delay: null });
+
+  const { client } = createTestMutationClient();
+  const s = new IterableStream<string>();
+
+  const mutTest = client.define({
+    id: "test-fast-failure",
+    mutate: async () => {
+      return (await s.next()).value;
+    },
+    describe: "Test the action",
+    describeResult: null,
+    optimistic: () => {},
+  });
+
+  let state = {};
+  function TestComponent() {
+    const { run, isMutating, isPending, errorMessage } = useMutate(mutTest);
+    state = { isMutating, isPending, errorMessage };
+    return (
+      <button data-testid="a" onClick={() => run()}>
+        button
+      </button>
+    );
+  }
+
+  render(<TestComponent />);
+  await act(() => user.click(screen.getByTestId("a")));
+  await act(async () => {
+    s.throw(new Error("damn!"));
+    vi.advanceTimersByTime(50);
+  });
+  await act(() => vi.advanceTimersByTime(500));
+  assertEquals(state, {
+    isMutating: false,
+    isPending: false,
+    errorMessage: "Could not test the action: damn!",
+  });
+});
+
 test("useMutate - local error and success handling", async () => {
   vi.useFakeTimers({ shouldAdvanceTime: true });
   const user = userEvent.setup({ delay: null });
-- 
2.54.0