diff --git a/sdk/typescript/tests-ts/prompt-only-start-timeout.test.ts b/sdk/typescript/tests-ts/prompt-only-start-timeout.test.ts
new file mode 100644
index 00000000..4eb4ea7f
--- /dev/null
+++ b/sdk/typescript/tests-ts/prompt-only-start-timeout.test.ts
@@ -0,0 +1,46 @@
+import { readFile } from "node:fs/promises";
+import { join } from "node:path";
+import { brotliDecompressSync } from "node:zlib";
+import { expect, test } from "bun:test";
+import { PLUGIN_ROOT } from "./plugin-root.js";
+
+test("gives prompt-only scan startup the five-minute scan timeout", async () => {
+  const parts = await Promise.all(
+    ["000", "001"].map((part) =>
+      readFile(join(PLUGIN_ROOT, "mcp", `server.mjs.br.part-${part}`)),
+    ),
+  );
+  const runtime = brotliDecompressSync(Buffer.concat(parts)).toString("utf8");
+  const source =
+    /async function executeWorkbench\([^\n]*\) \{[\s\S]*?\n\}/u.exec(
+      runtime,
+    )?.[0];
+  expect(source).toBeDefined();
+
+  const executeWorkbench = new Function(
+    "execFileAsync3",
+    "workbenchScriptPath",
+    "PLUGIN_ROOT",
+    "isJsonObject2",
+    `${source}\nreturn executeWorkbench;`,
+  )(
+    async (
+      _command: string,
+      _args: string[],
+      options: { timeout: number },
+    ) => ({ stdout: JSON.stringify({ timeout: options.timeout }) }),
+    () => "workbench.py",
+    PLUGIN_ROOT,
+    () => true,
+  ) as (command: string, args: string[]) => Promise<{ timeout: number }>;
+
+  expect(await executeWorkbench("python", ["start-prompt-only-scan"])).toEqual({
+    timeout: 300_000,
+  });
+  expect(await executeWorkbench("python", ["start-scan"])).toEqual({
+    timeout: 300_000,
+  });
+  expect(await executeWorkbench("python", ["other-operation"])).toEqual({
+    timeout: 30_000,
+  });
+});