# Custom Logto Sign-In UI

## Problem

Logto's default sign-in page uses Logto branding. While we configured colors and logos via `PATCH /api/sign-in-exp`, control over layout, typography, and components is limited. The sign-in experience is visually inconsistent with the cameleer3-server login page.

## Goal

Replace Logto's sign-in UI with a custom React SPA that visually matches the cameleer3-server login page, using `@cameleer/design-system` components for consistency across all deployment models.

## Scope

**MVP**: Username/password sign-in only.
**Later**: Sign-up, forgot password, social login, MFA.

## Architecture

### Source

Separate Vite+React app at `ui/sign-in/`. Own `package.json`, shares `@cameleer/design-system` v0.1.31.

### Build

Added as a Docker build stage in the SaaS `Dockerfile`. The dist is copied into the SaaS image at `/app/sign-in-dist/`.

### Deploy

SaaS entrypoint (`docker/saas-entrypoint.sh`) copies the built sign-in dist to a shared Docker volume (`signinui`). Logto reads from that volume via `CUSTOM_UI_PATH=/etc/logto/custom-ui`.

### Flow

```
User visits /platform/ → SaaS redirects to Logto OIDC
→ Logto sets interaction cookie, serves custom sign-in UI
→ User enters credentials → Experience API 4-step flow
→ Logto redirects back to /platform/callback with auth code
```

## Experience API

The custom UI communicates with Logto via the Experience API (stateful, cookie-based):

```
1. PUT  /api/experience                      → 204  (init SignIn)
2. POST /api/experience/verification/password → 200  { verificationId }
3. POST /api/experience/identification       → 204  (confirm identity)
4. POST /api/experience/submit               → 200  { redirectTo }
```

The interaction cookie is set by `/oidc/auth` before the user lands on the sign-in page. All API calls use `credentials: "same-origin"`.

## Visual Design

Matches cameleer3-server LoginPage exactly:
- Centered `Card` (400px max-width, 32px padding)
- Logo: favicon.svg + "cameleer3" text (24px bold)
- Random witty subtitle (13px muted)
- `FormField` + `Input` for username and password
- Amber `Button` (primary variant, full-width)
- `Alert` for errors
- Background: `var(--bg-base)` (light beige)
- Dark mode support via design-system tokens

## Files

### New

| File | Purpose |
|------|---------|
| `ui/sign-in/package.json` | React 19 + @cameleer/design-system + Vite 6 |
| `ui/sign-in/.npmrc` | Gitea npm registry for @cameleer scope |
| `ui/sign-in/tsconfig.json` | TypeScript config |
| `ui/sign-in/vite.config.ts` | Vite build config |
| `ui/sign-in/index.html` | Entry HTML |
| `ui/sign-in/src/main.tsx` | React mount + design-system CSS import |
| `ui/sign-in/src/App.tsx` | App shell |
| `ui/sign-in/src/SignInPage.tsx` | Login form with Experience API integration |
| `ui/sign-in/src/SignInPage.module.css` | CSS Modules (matches server LoginPage) |
| `ui/sign-in/src/experience-api.ts` | Typed Experience API client |
| `docker/saas-entrypoint.sh` | Copies sign-in dist to shared volume |
| `.gitattributes` | LF line endings |

### Modified

| File | Change |
|------|--------|
| `Dockerfile` | Add `sign-in-frontend` build stage, copy dist to runtime image |
| `docker-compose.yml` | Add `CUSTOM_UI_PATH` to Logto, `signinui` shared volume |

## Docker Timing

Logto starts before SaaS (dependency chain: postgres → logto → logto-bootstrap → cameleer-saas). The `CUSTOM_UI_PATH` volume is initially empty. This is acceptable because:
1. Nobody hits the sign-in page until redirected from `/platform/`
2. By that time, SaaS has started and copied the dist files
3. Logto serves static files at request time, not startup time

## Future Extensions

- Add React Router for multiple pages (sign-up, forgot password)
- Fetch `GET /api/.well-known/sign-in-exp` for dynamic sign-in method detection
- Social login buttons via `POST /api/experience/verification/social`
- MFA via `POST /api/experience/verification/totp`
- Consent page via `GET /api/interaction/consent`