FN-5811: respect persisted CLI onboarding completion marker

Ensure CLI onboarding only auto-runs once by honoring a valid persisted completion timestamp.

- add `isCliOnboardingComplete` helper to validate non-empty `cliOnboardingCompletedAt` marker values
- use the helper in `runOnboard` so reruns are blocked unless `--force` is provided
- extend onboard tests to cover marker validation and verify the rerun guidance log

Files changed:
 packages/cli/src/commands/__tests__/onboard.test.ts | 10 ++++++++++
 packages/cli/src/commands/onboard.ts                | 10 +++++++++-
 2 files changed, 19 insertions(+), 1 deletion(-)

Fusion-Task-Id: FN-5811
Fusion-Task-Lineage: 1547fd85-d06f-4ad0-adca-3a22709447fa

packages/cli/src/commands/__tests__/onboard.test.ts

@@ -85,6 +85,14 @@ function makeProviderAuth() {
 }
 
 describe("onboard", () => {
+  it("isCliOnboardingComplete handles marker presence correctly", () => {
+    expect(__testUtils.isCliOnboardingComplete({})).toBe(false);
+    expect(__testUtils.isCliOnboardingComplete({ cliOnboardingCompletedAt: "" })).toBe(false);
+    expect(__testUtils.isCliOnboardingComplete({ cliOnboardingCompletedAt: "2026-06-01T00:00:00.000Z" })).toBe(
+      true,
+    );
+  });
+
   beforeEach(() => {
     vi.clearAllMocks();
     for (const key of Object.keys(globalSettingsState)) delete globalSettingsState[key];
@@ -166,9 +174,11 @@ describe("onboard", () => {
   it("re-runs only with force when marker already exists", async () => {
     const providerAuth = makeProviderAuth();
     mockProviderAuthFactory.mockReturnValue(providerAuth);
+    const logSpy = vi.spyOn(console, "log").mockImplementation(() => {});
     globalSettingsState.cliOnboardingCompletedAt = "2026-06-01T00:00:00.000Z";
 
     await runOnboard({ input: inputFrom(["y", "3", "y", "y", "n", "y"]) });
+    expect(logSpy).toHaveBeenCalledWith("Onboarding already completed. Re-run with --force to run it again.");
     expect(providerAuth.setApiKey).not.toHaveBeenCalled();
     expect(mockRunInit).not.toHaveBeenCalled();
 

packages/cli/src/commands/onboard.ts

@@ -150,12 +150,19 @@ async function runSkippableStep(
   return true;
 }
 
+export function isCliOnboardingComplete(settings: { cliOnboardingCompletedAt?: string }): boolean {
+  return (
+    typeof settings.cliOnboardingCompletedAt === "string" &&
+    settings.cliOnboardingCompletedAt.trim().length > 0
+  );
+}
+
 export async function runOnboard(options: OnboardOptions = {}): Promise<void> {
   const globalSettingsStore = new GlobalSettingsStore();
   await globalSettingsStore.init();
   const settings = await globalSettingsStore.getSettings();
 
-  if (settings.cliOnboardingCompletedAt && !options.force) {
+  if (isCliOnboardingComplete(settings) && !options.force) {
     console.log("Onboarding already completed. Re-run with --force to run it again.");
     return;
   }
@@ -267,5 +274,6 @@ export const __testUtils = {
   createPromptSession,
   validateMaxConcurrent,
   runSkippableStep,
+  isCliOnboardingComplete,
   PROMPT_CANCELLED_ERROR,
 };