fix: fall back to non-PTY exec

src/agents/bash-tools.exec.pty-fallback.test.ts

@@ -0,0 +1,31 @@
+import { afterEach, expect, test, vi } from "vitest";
+
+import { resetProcessRegistryForTests } from "./bash-process-registry";
+
+afterEach(() => {
+  resetProcessRegistryForTests();
+  vi.resetModules();
+  vi.clearAllMocks();
+});
+
+test("exec falls back when PTY spawn fails", async () => {
+  vi.doMock("@lydell/node-pty", () => ({
+    spawn: () => {
+      const err = new Error("spawn EBADF");
+      (err as NodeJS.ErrnoException).code = "EBADF";
+      throw err;
+    },
+  }));
+
+  const { createExecTool } = await import("./bash-tools.exec");
+  const tool = createExecTool({ allowBackground: false });
+  const result = await tool.execute("toolcall", {
+    command: "printf ok",
+    pty: true,
+  });
+
+  expect(result.details.status).toBe("completed");
+  const text = result.content?.[0]?.text ?? "";
+  expect(text).toContain("ok");
+  expect(text).toContain("PTY spawn failed");
+});