fix(cli): forward agent name through setup (#124740)

Amp-Thread-ID: https://ampcode.com/threads/T-01a00b6b-e4e9-74af-bb31-30363fae6c89

Co-authored-by: Amp <amp@ampcode.com>

src/cli/program/register.setup.test.ts

@@ -522,6 +522,30 @@ describe("registerSetupCommand", () => {
     expect(setupCommandMock).not.toHaveBeenCalled();
   });
 
+  it.each([
+    ["guided", ["--wizard"]],
+    ["classic", ["--classic"]],
+    ["non-interactive", ["--non-interactive", "--accept-risk"]],
+  ])("forwards --agent-name through %s setup", async (_mode, modeArgs) => {
+    await runCli([
+      "setup",
+      ...modeArgs,
+      "--agent-name",
+      "robby",
+      "--workspace",
+      "/tmp/robby",
+      "--skip-bootstrap",
+    ]);
+
+    expect(lastWizardOptions()).toMatchObject({
+      agentName: "robby",
+      workspace: "/tmp/robby",
+      skipBootstrap: true,
+    });
+    expect(setupCommandMock).not.toHaveBeenCalled();
+    expect(runSystemAgentMock).not.toHaveBeenCalled();
+  });
+
   it("runs setup wizard command for migration import flags", async () => {
     await runCli([
       "setup",

src/cli/program/register.setup.ts

@@ -139,6 +139,7 @@ async function runOnboardingEntry(
   await setupWizardCommand(
     {
       workspace: readStringValue(options.workspace),
+      agentName: readStringValue(options.agentName),
       nonInteractive: Boolean(options.nonInteractive),
       acceptRisk: Boolean(options.acceptRisk),
       classic: Boolean(options.classic),
@@ -206,6 +207,7 @@ export function registerSetupCommand(program: Command): void {
       "--workspace <dir>",
       "Workspace proposal for guided setup; persisted by baseline/classic/non-interactive setup",
     )
+    .option("--agent-name <name>", "Name for the first agent (default: main)")
     .option("--wizard", "Run interactive onboarding", false)
     .option(
       "--baseline",