feat: Add --id option to connect to existing remote agents via tunnel (#7999)

Author: sestinj

extensions/cli/src/commands/remote.test.ts

@@ -145,6 +145,77 @@ describe("remote command", () => {
     expect(mockConsoleLog).not.toHaveBeenCalled();
   });
 
+  it("should fetch tunnel and connect when id option is provided", async () => {
+    const agentId = "agent-789";
+
+    mockFetch
+      .mockResolvedValueOnce({
+        ok: true,
+        json: async () => ({ url: "ws://tunnel-url.com", port: 9090 }),
+      })
+      .mockResolvedValue({
+        ok: true,
+        json: async () => ({
+          id: "test-agent-id",
+          url: "ws://test-url.com",
+          port: 8080,
+        }),
+      });
+
+    await remote("test prompt", { id: agentId });
+
+    expect(mockFetch).toHaveBeenCalledWith(
+      new URL(`agents/${agentId}/tunnel`, mockEnv.env.apiBase),
+      expect.objectContaining({
+        method: "POST",
+        headers: {
+          "Content-Type": "application/json",
+          Authorization: "Bearer test-token",
+        },
+      }),
+    );
+
+    expect(mockStartRemoteTUIChat.startRemoteTUIChat).toHaveBeenCalledWith(
+      "ws://tunnel-url.com",
+      "test prompt",
+    );
+  });
+
+  it("should output JSON without starting TUI when using --id with --start", async () => {
+    const agentId = "agent-456";
+    const tunnelResponse = { url: "ws://existing-tunnel.com", port: 7070 };
+
+    mockFetch.mockResolvedValueOnce({
+      ok: true,
+      json: async () => tunnelResponse,
+    });
+
+    await remote("test prompt", { id: agentId, start: true });
+
+    expect(mockFetch).toHaveBeenCalledWith(
+      new URL(`agents/${agentId}/tunnel`, mockEnv.env.apiBase),
+      expect.objectContaining({
+        method: "POST",
+        headers: {
+          "Content-Type": "application/json",
+          Authorization: "Bearer test-token",
+        },
+      }),
+    );
+
+    expect(mockStartRemoteTUIChat.startRemoteTUIChat).not.toHaveBeenCalled();
+    expect(mockConsoleLog).toHaveBeenCalledWith(
+      JSON.stringify({
+        status: "success",
+        message: "Remote agent tunnel connection details",
+        url: tunnelResponse.url,
+        containerPort: tunnelResponse.port,
+        agentId,
+        mode: "existing_agent",
+      }),
+    );
+  });
+
   it("should handle proper request body structure with all fields", async () => {
     const testIdempotencyKey = "structured-test-key";
 
@@ -298,10 +369,10 @@ describe("remote command", () => {
       repoUrl: "https://github.com/user/test-repo.git",
       name: expect.stringMatching(/^devbox-\d+$/),
       prompt: "test prompt",
-      idempotencyKey: undefined,
       agent: undefined,
       config: undefined,
     });
+    expect(requestBody).not.toHaveProperty("idempotencyKey");
   });
 
   describe("start mode (-s / --start flag)", () => {