diff --git a/packages/server/src/concurrencyGuard.test.ts b/packages/server/src/concurrencyGuard.test.ts
new file mode 100644
index 00000000..6427df31
--- /dev/null
+++ b/packages/server/src/concurrencyGuard.test.ts
@@ -0,0 +1,18 @@
+import { describe, it, expect, afterEach } from "vitest";
+import { getMaxConcurrentTasks } from "./concurrencyGuard.js";
+
+describe("concurrencyGuard default cap", () => {
+  afterEach(() => {
+    delete process.env.MAX_CONCURRENT_TASKS;
+  });
+
+  it("defaults to 5 when MAX_CONCURRENT_TASKS is unset", () => {
+    delete process.env.MAX_CONCURRENT_TASKS;
+    expect(getMaxConcurrentTasks()).toBe(5);
+  });
+
+  it("honors MAX_CONCURRENT_TASKS env override", () => {
+    process.env.MAX_CONCURRENT_TASKS = "12";
+    expect(getMaxConcurrentTasks()).toBe(12);
+  });
+});
diff --git a/packages/server/src/concurrencyGuard.ts b/packages/server/src/concurrencyGuard.ts
index b744aed1..50c8d79c 100644
--- a/packages/server/src/concurrencyGuard.ts
+++ b/packages/server/src/concurrencyGuard.ts
@@ -1,4 +1,4 @@
-const getMax = () => Number(process.env.MAX_CONCURRENT_TASKS ?? 3);
+const getMax = () => Number(process.env.MAX_CONCURRENT_TASKS ?? 5);
 
 let activeTasks = 0;