Setup UI cannot safely back out of the Gateway installed handoff

Bug

Setup navigation around the Gateway installed handoff is asymmetric and can leave Gateway wizard state active after the user backs out.

On current main:

• Gateway installed (Step 4 of 6) offers Start OpenClaw onboard, but no Back action.
• Pressing Back on the first server-defined OpenClaw onboard question returns to Set up OpenClaw (Step 2 of 6), skipping the installed-gateway handoff and Capabilities page.
• That route does not cancel the active Gateway wizard session before leaving.
• A connection completing after navigation can still become the active client, and step history is not cleared on every fresh wizard start.

This affects both initial local WSL setup and the direct Settings > OpenClaw Onboard > Open onboarding entry point.

@jacobtomlinson, tagging you for setup and Local AI UX context.

Reproduction

1. Use an app-managed local WSL gateway.
2. Complete local setup, or open Settings > OpenClaw Onboard > Open onboarding.
3. Reach the Gateway installed screen.
4. Observe that the screen has Start OpenClaw onboard, but no Back button.
5. Start OpenClaw onboard and wait for its first question.
6. Press Back.
7. Observe that setup returns to Set up OpenClaw rather than Gateway installed, without first cancelling the active Gateway wizard session.

Expected behavior

• Gateway installed > Back should return to the Capabilities flow with the current setup configuration retained.
• Back on the first OpenClaw onboard question should invalidate pending client work, cancel the active Gateway wizard session, and return to Gateway installed.
• A client connection that completes after navigation should be disconnected instead of becoming active.
• Starting a fresh wizard should clear local step history.

This boundary behavior does not imply support for rewinding later Gateway-owned wizard questions.

Actual behavior

• The Gateway installed handoff is forward-only.
• Back on the first onboarding question navigates directly to Welcome.
• The active wizard session is not cancelled on that route.
• Pending connection and stale-history state can survive navigation.

Environment

• Version or commit: current main at 911f36860b2d
• OS or platform: Windows setup UI with an app-managed local WSL gateway
• Relevant configuration: first-run local setup or direct installed-gateway onboarding from Settings

Evidence

Current main renders only the onboarding button on the Gateway installed milestone:

https://github.com/openclaw/openclaw-windows-node/blob/911f36860b2d9f45c4c7ccddfb94ddb60b3ee2b0/src/OpenClaw.SetupEngine.UI/Pages/ProgressPage.xaml#L114-L128

Current main assigns the connected client before checking whether navigation invalidated the operation:

https://github.com/openclaw/openclaw-windows-node/blob/911f36860b2d9f45c4c7ccddfb94ddb60b3ee2b0/src/OpenClaw.SetupEngine.UI/Pages/WizardPage.xaml.cs#L107-L138

The first-question Back path navigates directly to Welcome:

https://github.com/openclaw/openclaw-windows-node/blob/911f36860b2d9f45c4c7ccddfb94ddb60b3ee2b0/src/OpenClaw.SetupEngine.UI/Pages/WizardPage.xaml.cs#L769-L781

Candidate fix branch:

https://github.com/joelagnel/openclaw-windows-node/tree/fix/setup-ui-reversible-onboarding-navigation

No pull request has been opened so the behavior can be tested first.

Additional context

• #1172 covers the distinct problem of attempting to rewind after advancing within the Gateway-owned question sequence.
• #688 was the broader historical request for Back navigation throughout setup.
• #1243 concerns exposing reconfiguration from the Local AI page. It can lead into this installed-gateway onboarding path but is not the same navigation defect.

Read src/OpenClaw.SetupEngine.UI/Pages/ProgressPage.xaml at the Gateway installed milestone and WizardPage.xaml.cs at the connection and first-question Back paths. Trace navigation invalidation, wizard cancellation, client connection ownership, and step-history reset. Done means Back reaches the expected milestones, pending connections cannot become active after navigation, and fresh wizard starts have no stale history.