@@ -102,6 +102,32 @@ describe("createRequestQueue", () => {
     expect(input.queue.inflight()).toBe(0)
   })
 
+  test("MCP discovery cannot occupy every slot ahead of chat reads", async () => {
+    for (const path of ["/api/command", "/api/mcp", "/api/mcp/resource"]) {
+      const input = setup({ limit: 4, slowLimit: 2 })
+      const discovery = Array.from({ length: 4 }, (_, index) =>
+        input.queue.fetch(`http://server${path}?location[directory]=%2Fproject-${index}`),
+      )
+      const chat = input.queue.fetch("http://server/api/session/ses_1/message")
+      try {
+        expect(input.pending.map((item) => new URL(item.url).pathname)).toEqual([
+          path,
+          path,
+          "/api/session/ses_1/message",
+        ])
+        expect(input.queue.inflight()).toBe(3)
+        expect(input.queue.queued()).toBe(2)
+      } finally {
+        input.pending.forEach((item) => item.resolve())
+        await input.settle()
+        input.pending.forEach((item) => item.resolve())
+        await Promise.all([...discovery, chat])
+      }
+      expect(input.queue.inflight()).toBe(0)
+      expect(input.queue.queued()).toBe(0)
+    }
+  })
+
   test("never counts the event stream against the budget", async () => {
     const input = setup({ limit: 1 })
     void input.queue.fetch("http://server/api/session")
 
@@ -5,11 +5,11 @@ type Entry = { method: string; url: string; at: number; slow: boolean }
 // a burst stalls probes and user actions inside the browser where nothing can observe it.
 export const requestQueueLimit = 4
 
-// Endpoints that shell out to git or walk the filesystem take seconds on a large repository. They
-// may hold at most this many slots, so a session mount's small reads never queue behind them.
+// Git/filesystem endpoints and MCP catalogs can take seconds, including MCP startup and discovery.
+// They may hold at most this many slots, so a session mount's small reads never queue behind them.
 export const requestQueueSlowLimit = 2
 
-export const slowRequestPaths = ["/api/vcs", "/api/worktree"]
+export const slowRequestPaths = ["/api/vcs", "/api/worktree", "/api/command", "/api/mcp"]
 
 // A mount legitimately fires a dozen requests at once; only a request that has waited this long
 // for a slot indicates the server is not keeping up.