Replace @tanstack/pacer with @tanstack/pacer-lite

.changeset/migrate-to-pacer-lite.md

@@ -0,0 +1,5 @@
+---
+"@tanstack/db": patch
+---
+
+Migrated paced mutations implementation from `@tanstack/pacer` to `@tanstack/pacer-lite`. The lite version provides the same core functionality with minimal overhead and no external dependencies, making it more suitable for library use. This is an internal implementation change with no impact on the public API - all paced mutation strategies (debounce, throttle, queue) continue to work exactly as before.

packages/db/package.json

@@ -5,7 +5,7 @@
   "dependencies": {
     "@standard-schema/spec": "^1.0.0",
     "@tanstack/db-ivm": "workspace:*",
-    "@tanstack/pacer": "^0.16.3"
+    "@tanstack/pacer-lite": "^0.1.0"
   },
   "devDependencies": {
     "@vitest/coverage-istanbul": "^3.2.4",

packages/db/src/strategies/debounceStrategy.ts

@@ -1,4 +1,4 @@
-import { Debouncer } from "@tanstack/pacer/debouncer"
+import { LiteDebouncer } from "@tanstack/pacer-lite/lite-debouncer"
 import type { DebounceStrategy, DebounceStrategyOptions } from "./types"
 import type { Transaction } from "../transactions"
 
@@ -28,7 +28,7 @@ import type { Transaction } from "../transactions"
 export function debounceStrategy(
   options: DebounceStrategyOptions
 ): DebounceStrategy {
-  const debouncer = new Debouncer(
+  const debouncer = new LiteDebouncer(
     (callback: () => Transaction) => callback(),
     options
   )

packages/db/src/strategies/queueStrategy.ts

@@ -1,4 +1,4 @@
-import { AsyncQueuer } from "@tanstack/pacer/async-queuer"
+import { LiteQueuer } from "@tanstack/pacer-lite/lite-queuer"
 import type { QueueStrategy, QueueStrategyOptions } from "./types"
 import type { Transaction } from "../transactions"
 
@@ -44,16 +44,29 @@ import type { Transaction } from "../transactions"
  * ```
  */
 export function queueStrategy(options?: QueueStrategyOptions): QueueStrategy {
-  const queuer = new AsyncQueuer<() => Transaction>(
-    async (fn) => {
-      const transaction = fn()
-      // Wait for the transaction to be persisted before processing next item
-      // Note: fn() already calls commit(), we just wait for it to complete
-      await transaction.isPersisted.promise
+  // Manual promise chaining to ensure async serialization
+  // LiteQueuer (unlike AsyncQueuer from @tanstack/pacer) lacks built-in async queue
+  // primitives and concurrency control. We compensate by manually chaining promises
+  // to ensure each transaction completes before the next one starts.
+  let processingChain = Promise.resolve()
+
+  const queuer = new LiteQueuer<() => Transaction>(
+    (fn) => {
+      // Chain each transaction to the previous one's completion
+      processingChain = processingChain
+        .then(async () => {
+          const transaction = fn()
+          // Wait for the transaction to be persisted before processing next item
+          await transaction.isPersisted.promise
+        })
+        .catch(() => {
+          // Errors are handled via transaction.isPersisted.promise and surfaced there.
+          // This catch prevents unhandled promise rejections from breaking the chain,
+          // ensuring subsequent transactions can still execute even if one fails.
+        })
     },
     {
-      concurrency: 1, // Process one at a time to ensure serialization
-      wait: options?.wait,
+      wait: options?.wait ?? 0,
       maxSize: options?.maxSize,
       addItemsTo: options?.addItemsTo ?? `back`, // Default FIFO: add to back
       getItemsFrom: options?.getItemsFrom ?? `front`, // Default FIFO: get from front

packages/db/src/strategies/throttleStrategy.ts

@@ -1,4 +1,4 @@
-import { Throttler } from "@tanstack/pacer/throttler"
+import { LiteThrottler } from "@tanstack/pacer-lite/lite-throttler"
 import type { ThrottleStrategy, ThrottleStrategyOptions } from "./types"
 import type { Transaction } from "../transactions"
 
@@ -48,7 +48,7 @@ import type { Transaction } from "../transactions"
 export function throttleStrategy(
   options: ThrottleStrategyOptions
 ): ThrottleStrategy {
-  const throttler = new Throttler(
+  const throttler = new LiteThrottler(
     (callback: () => Transaction) => callback(),
     options
   )