From 16b383ab6fcb3bf9fbed93d62fa266028e4f6fae Mon Sep 17 00:00:00 2001
From: Sameh Khamis <sameh@halfpixel.ai>
Date: Tue, 3 Nov 2026 09:16:52 -0800
Subject: [PATCH] fix(area): detach a lookup's abort listener once it settles

Each resolve() that raced the caller's signal added an abort listener and
never removed it, so a long-lived signal collected one listener per
completed lookup. The listener is now removed when the call settles and
is not added at all to a signal that is already aborted.
---
 src/data/areaResolver.js       | 21 +++++++++++++--------
 src/data/areaResolver.test.mjs | 30 ++++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+), 8 deletions(-)

diff --git a/src/data/areaResolver.js b/src/data/areaResolver.js
index 1134e37ca..f222d3c8c 100644
--- a/src/data/areaResolver.js
+++ b/src/data/areaResolver.js
@@ -626,24 +626,29 @@ export function createAreaResolver({
           );
         }),
       );
+    // Detached once this call settles: a caller's long-lived signal must not
+    // collect one listener per completed lookup.
+    let cancelled = null;
     if (signal)
       racers.push(
         new Promise((resolveAbort) => {
-          const cancelled = () =>
-            resolveAbort({
-              ok: false,
-              code: 'CANCELLED',
-              cancelled: true,
-              error: 'Superseded.',
-            });
-          if (signal.aborted) cancelled();
+          const superseded = {
+            ok: false,
+            code: 'CANCELLED',
+            cancelled: true,
+            error: 'Superseded.',
+          };
+          if (signal.aborted) return resolveAbort(superseded);
+          cancelled = () => resolveAbort(superseded);
           signal.addEventListener?.('abort', cancelled, { once: true });
+          return undefined;
         }),
       );
     try {
       return finish(await Promise.race(racers));
     } finally {
       clearTimeout(timer);
+      if (cancelled) signal.removeEventListener?.('abort', cancelled);
     }
   }
 
diff --git a/src/data/areaResolver.test.mjs b/src/data/areaResolver.test.mjs
index 4c411b5ac..f38f1448e 100644
--- a/src/data/areaResolver.test.mjs
+++ b/src/data/areaResolver.test.mjs
@@ -556,6 +556,36 @@ test('distinct area lookups are hard-bounded while same-key callers still coales
   assert.equal(b.ok, true);
 });
 
+test('settled lookups leave no listener on the caller\'s signal', async () => {
+  const { resolver } = makeResolver();
+  const controller = new AbortController();
+  let added = 0;
+  let removed = 0;
+  const add = controller.signal.addEventListener.bind(controller.signal);
+  const remove = controller.signal.removeEventListener.bind(controller.signal);
+  controller.signal.addEventListener = (...args) => {
+    if (args[0] === 'abort') added += 1;
+    return add(...args);
+  };
+  controller.signal.removeEventListener = (...args) => {
+    if (args[0] === 'abort') removed += 1;
+    return remove(...args);
+  };
+  for (const query of ['Texas', 'Bagmati', 'Nowhere at all'])
+    await resolver.resolve({ query }, { signal: controller.signal });
+  assert.ok(added > 0, 'the lookups listened while running');
+  assert.equal(removed, added, 'every listener is detached once settled');
+
+  const aborted = AbortSignal.abort();
+  let attached = 0;
+  aborted.addEventListener = () => {
+    attached += 1;
+  };
+  const late = await resolver.resolve({ query: 'Punjab, Pakistan' }, { signal: aborted });
+  assert.equal(late.code, 'CANCELLED');
+  assert.equal(attached, 0, 'an aborted signal gets no listener');
+});
+
 test('resolver disposal aborts provider lifetime and prevents late store/cache writes', async () => {
   let release;
   let providerSignal;