fix(app): start MCP servers only for open directories (#28937)

packages/app/src/utils/refcount.test.ts

@@ -0,0 +1,49 @@
+import { describe, expect, test } from "bun:test"
+import { createRoot } from "solid-js"
+import { createRefCountMap } from "./refcount"
+import { pathKey } from "./path-key"
+
+describe("createRefCountMap", () => {
+  test("removes an item after its last owner is disposed", () => {
+    const removed: string[] = []
+    const map = createRefCountMap(
+      (key) => key,
+      (key) => removed.push(key),
+    )
+    const first = createRoot((dispose) => {
+      map("/project")
+      return dispose
+    })
+    const second = createRoot((dispose) => {
+      map("/project")
+      return dispose
+    })
+
+    first()
+    expect(removed).toEqual([])
+    second()
+    expect(removed).toEqual(["/project"])
+  })
+
+  test("keeps equivalent path consumers until the last owner is disposed", () => {
+    const removed: string[] = []
+    const map = createRefCountMap(
+      (key) => key,
+      (key) => removed.push(key),
+      pathKey,
+    )
+    const first = createRoot((dispose) => {
+      map("C:\\repo")
+      return dispose
+    })
+    const second = createRoot((dispose) => {
+      map("C:/repo/")
+      return dispose
+    })
+
+    first()
+    expect(removed).toEqual([])
+    second()
+    expect(removed).toEqual(["C:/repo"])
+  })
+})