feat: support setting concurrency limits in web search

composables/usePLimit.ts

@@ -0,0 +1,30 @@
+import pLimit from 'p-limit'
+
+/**
+ * The concurrency value used by the global limit.
+ * This represents the *actual* limit value.
+ * The value in `globalLimit` should not be used, because `deepResearch` uses recursive calls,
+ * and `globalLimit.concurrency` can be much higher than the actual one.
+ */
+let globalLimitConcurrency = 2
+const globalLimit = pLimit(globalLimitConcurrency)
+
+export function usePLimit() {
+  const { config } = useConfigStore()
+
+  if (
+    config.webSearch.concurrencyLimit &&
+    config.webSearch.concurrencyLimit >= 1 &&
+    globalLimitConcurrency !== config.webSearch.concurrencyLimit
+  ) {
+    console.log(
+      `[usePLimit] Updating concurrency from ${globalLimitConcurrency} to ${config.webSearch.concurrencyLimit}. Current concurrency: ${globalLimit.concurrency}`,
+    )
+    let newLimit = config.webSearch.concurrencyLimit
+    let diff = newLimit - globalLimitConcurrency
+    globalLimitConcurrency = newLimit
+    globalLimit.concurrency += diff
+  }
+
+  return globalLimit
+}