Fix garbage collection issue with Infinity setting

.changeset/fix-gc-infinity.md

@@ -0,0 +1,5 @@
+---
+'@tanstack/db': patch
+---
+
+Fix `gcTime: Infinity` causing immediate garbage collection instead of disabling GC. JavaScript's `setTimeout` coerces `Infinity` to `0` via ToInt32, so we now explicitly check for non-finite values.

packages/db/src/collection/lifecycle.ts

@@ -180,8 +180,10 @@ export class CollectionLifecycleManager<
 
     const gcTime = this.config.gcTime ?? 300000 // 5 minutes default
 
-    // If gcTime is 0, GC is disabled
-    if (gcTime === 0) {
+    // If gcTime is 0 or Infinity (or any non-finite value), GC is disabled.
+    // Note: setTimeout with Infinity coerces to 0 via ToInt32, causing immediate GC,
+    // so we must explicitly check for non-finite values here.
+    if (gcTime === 0 || !Number.isFinite(gcTime)) {
       return
     }
 

packages/db/tests/collection-lifecycle.test.ts

@@ -360,6 +360,26 @@ describe(`Collection Lifecycle Management`, () => {
       expect(mockSetTimeout).not.toHaveBeenCalled()
       expect(collection.status).not.toBe(`cleaned-up`)
     })
+
+    it(`should disable GC when gcTime is Infinity`, () => {
+      const collection = createCollection<{ id: string; name: string }>({
+        id: `infinity-gc-test`,
+        getKey: (item) => item.id,
+        gcTime: Infinity, // Disabled GC via Infinity
+        sync: {
+          sync: () => {},
+        },
+      })
+
+      const subscription = collection.subscribeChanges(() => {})
+      subscription.unsubscribe()
+
+      // Should not start any timer when gcTime is Infinity
+      // Note: Without this fix, setTimeout(fn, Infinity) would coerce to 0,
+      // causing immediate GC instead of never collecting
+      expect(mockSetTimeout).not.toHaveBeenCalled()
+      expect(collection.status).not.toBe(`cleaned-up`)
+    })
   })
 
   describe(`Manual Preload and Cleanup`, () => {