fix: merge login shell PATH for gateway exec

src/infra/shell-env.path.test.ts

@@ -0,0 +1,34 @@
+import { afterEach, describe, expect, it, vi } from "vitest";
+
+import { getShellPathFromLoginShell, resetShellPathCacheForTests } from "./shell-env.js";
+
+describe("getShellPathFromLoginShell", () => {
+  afterEach(() => resetShellPathCacheForTests());
+
+  it("returns PATH from login shell env", () => {
+    if (process.platform === "win32") return;
+    const exec = vi
+      .fn()
+      .mockReturnValue(Buffer.from("PATH=/custom/bin\0HOME=/home/user\0", "utf-8"));
+    const result = getShellPathFromLoginShell({ env: { SHELL: "/bin/sh" }, exec });
+    expect(result).toBe("/custom/bin");
+  });
+
+  it("caches the value", () => {
+    if (process.platform === "win32") return;
+    const exec = vi.fn().mockReturnValue(Buffer.from("PATH=/custom/bin\0", "utf-8"));
+    const env = { SHELL: "/bin/sh" } as NodeJS.ProcessEnv;
+    expect(getShellPathFromLoginShell({ env, exec })).toBe("/custom/bin");
+    expect(getShellPathFromLoginShell({ env, exec })).toBe("/custom/bin");
+    expect(exec).toHaveBeenCalledTimes(1);
+  });
+
+  it("returns null on exec failure", () => {
+    if (process.platform === "win32") return;
+    const exec = vi.fn(() => {
+      throw new Error("boom");
+    });
+    const result = getShellPathFromLoginShell({ env: { SHELL: "/bin/sh" }, exec });
+    expect(result).toBeNull();
+  });
+});