---
phase: 03-wizard-ui
plan: "03"
subsystem: wizard-step
tags: [react, forms, react-hook-form, zod, tdd, validation]
dependency_graph:
  requires:
    - "03-01: test infrastructure and RED baseline"
    - "03-02: BackendCard UI atom"
    - "src/store/context.tsx: WizardProvider, useWizard"
    - "src/store/types.ts: WizardAction, BackendType"
  provides:
    - "src/components/wizard/BackendSelectionStep.tsx"
  affects:
    - "03-05: App step routing (renders BackendSelectionStep at step 0)"
tech_stack:
  added: []
  patterns:
    - "react-hook-form handleSubmit triggered by card click via pendingBackend ref"
    - "mode: onSubmit + reValidateMode: onChange — no errors on fill, live errors after first failed submit"
    - "SET_REMOTE_PARAMS({}) on backend selection — clears stale params without wiping deployment"
key_files:
  created:
    - "src/components/wizard/BackendSelectionStep.tsx"
  modified:
    - "src/components/wizard/BackendSelectionStep.test.tsx"
decisions:
  - "[03-03] waitFor used in async validation tests — handleSubmit is async, React state updates need await"
  - "[03-03] pendingBackend useRef stores clicked backend type before handleSubmit fires — avoids closure staleness"
  - "[03-03] Dispatch order: SET_REMOTE_NAME -> SET_BACKEND_TYPE -> SET_REMOTE_PARAMS({}) -> SET_STEP(1)"
metrics:
  duration: "2 min"
  completed: "2026-03-27"
  tasks_completed: 1
  files_created: 1
  files_modified: 1
---

# Phase 03 Plan 03: BackendSelectionStep Summary

BackendSelectionStep implemented with TDD: remote name zod validation (onSubmit mode) and popularity-sorted backend card grid that validates name before dispatching three store actions on card click.

## Tasks Completed

| Task | Name | Commit | Files |
|------|------|--------|-------|
| RED | Add failing tests for BackendSelectionStep | cf06d72 | src/components/wizard/BackendSelectionStep.test.tsx |
| GREEN | Implement BackendSelectionStep | b47f607 | src/components/wizard/BackendSelectionStep.tsx, BackendSelectionStep.test.tsx |

## What Was Built

**BackendSelectionStep** — Step 0 of the wizard. Renders a remote name text field (top) with zod-powered react-hook-form validation, followed by three backend selection cards in popularity order (Azure Blob Storage, Amazon S3, S3-Compatible).

Clicking a card triggers `handleSubmit` internally — the form validates the remote name before dispatching actions. If the name is invalid, an inline error appears and navigation does not proceed. On valid submit, the component dispatches:
1. `SET_REMOTE_NAME` — stores the validated name
2. `SET_BACKEND_TYPE` — stores the selected backend
3. `SET_REMOTE_PARAMS({})` — clears any stale backend-specific params
4. `SET_STEP(1)` — advances to step 1

The component never dispatches `RESET` — deployment options (includeInstall, configPath, scriptTargets) are preserved across back-navigation.

## TDD Execution

- **RED commit:** `cf06d72` — 10 test stubs replaced with real assertions, failing because component did not exist
- **GREEN commit:** `b47f607` — Component implemented, all 10 tests pass

## Verification

```
Test Files  1 passed (1)
Tests      10 passed (10)
```

All WIZD-01 and WIZD-04 cases GREEN. Full suite: 71 passing, 16 RED (expected `expect.fail` stubs from Plans 03-04 and 03-05).

## Deviations from Plan

### Auto-fixed Issues

**1. [Rule 1 - Bug] Added waitFor to async validation tests**
- **Found during:** GREEN phase test run
- **Issue:** `handleSubmit` is async — React state updates from zod validation don't flush synchronously. Tests using `fireEvent.click` without `waitFor` found no alert in DOM.
- **Fix:** Imported `waitFor` from `@testing-library/react`; wrapped post-click assertions in `await waitFor(...)` for the three tests that assert on validation error presence/absence.
- **Files modified:** src/components/wizard/BackendSelectionStep.test.tsx
- **Commit:** b47f607

## Self-Check

- [x] `src/components/wizard/BackendSelectionStep.tsx` exists
- [x] `src/components/wizard/BackendSelectionStep.test.tsx` updated with real tests
- [x] Commit `cf06d72` exists (RED tests)
- [x] Commit `b47f607` exists (GREEN implementation)
- [x] All 10 BackendSelectionStep tests GREEN
- [x] No regressions in previously passing tests (71 passing)