# Module: `src/components/HelpModal.tsx`

> **Source**: `src/components/HelpModal.tsx` (62 lines)
> **Topo batch**: B2 (uses `react-i18next` for the language flag only; no intra-repo deps)

## Purpose

A modal dialog that surfaces annotation guidelines and the keyboard-shortcut cheat-sheet. Triggered from `Header.tsx` → "Help" entry. Replaces the legacy WPF `HelpWindow.xaml` (`_docs/legacy/wpf-era.md` §4).

## Public interface

```ts
interface Props {
  open: boolean
  onClose: () => void
}
export default function HelpModal(props: Props): JSX.Element | null
```

When `open === false`, returns `null`. Otherwise renders a centered `<div>` overlay.

## Internal logic

- Reads `i18n.language` from `useTranslation()`; treats anything other than `'ua'` as English (`lang = i18n.language === 'ua' ? 'ua' : 'en'`).
- `GUIDELINES`: a hardcoded array of 6 `{ en, ua }` rules covering annotation quality. **Hardcoded — not loaded via the `i18n` resource bundle**, despite the module already importing `useTranslation`. (Inconsistency vs. the rest of the SPA — flag for Step 4.)
- Renders the guidelines as a numbered list and a 12-row keyboard-shortcut grid (`Space`, `← →`, `Ctrl + ← →`, `Enter`, …).
- Click on the dim backdrop closes the modal; click inside is `stopPropagation`'d.
- `Close` button is a styled `<button>` calling `onClose()`.

## Dependencies

- **Internal**: none.
- **External**: `react-i18next` (for `useTranslation()` only — to detect the language; *not* for content lookup).

## Consumers (intra-repo)

- `src/components/Header.tsx` — owns `open` state and the trigger button.

## Data models

The `GUIDELINES` array — module-private. Each entry: `{ en: string, ua: string }`.

## Configuration

The keyboard-shortcut grid hardcodes the same shortcut taxonomy that `_docs/ui_design/README.md` §"Keyboard Shortcuts" enumerates. Verify parity during Step 4.

## External integrations

None.

## Security

None directly. Note that ESCAPE-key handling appears in the *sibling* `ConfirmDialog` but **not** here — Esc currently does NOT close `HelpModal`. Backdrop click is the only dismiss path beyond the Close button. Inconsistent UX; flag for Step 4 verification against the UI spec.

## Tests

None.

## Notes / open questions

- The 6 guidelines stored as `{ en, ua }` literals duplicate the Annotation Quality Guidelines documented in `_docs/ui_design/README.md` §"Annotation Quality Guidelines" (which lists six rules with subtly different wording). Choose one source of truth in Step 5; preferred is to lift the strings into `en.json` / `ua.json` like the rest of the SPA.
- The `<h2>` "How to Annotate" heading is hardcoded English; should also be translated.
- The `lang === 'ua' ? 'ua' : 'en'` branch silently treats every non-Ukrainian language as English — only correct as long as exactly two locales exist. If a third locale is added, this needs to use the `i18n` lookup table.
- Width is hardcoded `w-[500px]` and `max-h-[80vh]`. Does not adapt to mobile breakpoints documented in `_docs/ui_design/README.md` §"Responsive Breakpoints" (640px). Flag.