feat(desktop): polish onboarding harness

[cynfria]

Why

Refresh the machine onboarding harness and default-agent settings steps to match the new two-step design while preserving the existing setup/config functionality.

What

• Reskin the harness selection cards with detected provider logos, loading state, animated selection, and setup/installed badges
• Split and compact the default agent settings step with custom dropdowns, disabled placeholders, and provider-gated model/effort choices
• Add the community-step back path to return to agent defaults during onboarding review
• Extend onboarding e2e coverage for loading, selection, setup, dropdown gating, and save coalescing

Risk Assessment

Medium-low — changes are concentrated in desktop onboarding and shared agent config field presentation. Existing settings defaults are preserved, and the focused onboarding flow is covered by e2e tests.

References

• bin/pnpm --dir desktop exec biome check ... passed
• bin/pnpm --dir desktop run typecheck passed
• bin/pnpm --dir desktop exec playwright test --project=smoke tests/e2e/onboarding-agent-defaults.spec.ts passed, 12 tests
• Pre-push hooks passed: desktop, mobile, Tauri, Rust, and full test hook

Generated with Codex

[wesbillman]

Two existing-flow regressions block this as written; this is not a UI-only change:

1. A successful installer result bypasses readiness/authentication. runtimeCanAdvanceOnboarding(runtime, installSuccess) returns true unconditionally when installSuccess is true. For a newly installed Claude/Codex CLI, installation does not establish account auth, and the query invalidation/re-probe may still report logged out/unknown. Nevertheless the card becomes “INSTALLED” and Next advances immediately. The new keyboard test codifies this shortcut with a stale not-installed catalog rather than proving the re-probed runtime is actually available and authenticated. Keep installation success distinct from runtime readiness; advance only after the refreshed catalog satisfies the normal availability/auth gate (and show/setup auth otherwise).

2. Rapid multi-selection can persist an older choice than the UI shows. Every toggle starts an independent getGlobalAgentConfig → setGlobalAgentConfig request. Unlike the old single-select flow, cards remain interactive while isSelectionSaving, so A→A+B launches overlapping writes. The sequence number only suppresses stale React callbacks; it does not serialize/cancel backend writes. If the first write finishes last, persisted preferred_runtime is A while local selection/defaults show B (and Next re-enables when only the newest request finishes, even if an older write is still running). Serialize/coalesce selection writes and keep the gate saving until the queue drains; add a delayed/out-of-order toggle regression test.

[wesbillman]

Re-reviewed the full branch and reduced it to UI-only runtime branding. Existing single-select onboarding, navigation, auth/readiness, persistence, shared settings, and test-bridge behavior are restored; unsupported Gemini branding is removed. The remaining diff only adds supported Claude/Codex/Goose assets, a runtime icon renderer with catalog-avatar/terminal fallback, and uses it in the existing runtime cards. Clean desktop build, typecheck, Biome, and onboarding-agent-defaults smoke suite (15/15) pass on current main.

Superseded: this approval incorrectly removed the intended onboarding redesign. The redesign is restored at 4742615; a fresh approval will follow current-head CI and merge-base review.