# Player browser application

Milestone 008 provides the responsive player-facing browser application. The
browser remains a renderer and input device: it sends movement and key-drop
intentions, and it never calculates a legal move, inventory change, timer,
visibility region, compass result, or match result.

## Local assets

The application consists of `index.html`, `player.css`, `player.js`, and the
locally authored `icons.svg` sprite. The deterministic asset build compresses
each file with gzip for LittleFS. There are no remote fonts, frameworks,
analytics, icon services, or runtime network dependencies beyond the local ESP.

## Input contract

Arrow keys and WASD map to `north`, `east`, `south`, and `west` move intentions.
Touch swipes use the same four strings after a 28 CSS-pixel threshold. Phone
layouts hide the direction pad and retain swipes; tablet and desktop layouts
show the direction pad and also accept swipes. The persistent `OK` control
sends `drop_key` and exposes the accessible label `Сбросить ключ`.

Commands use the version-one protocol envelope and contain intention data only:

```json
{"v":1,"type":"move","seq":7,"requestId":"move-7","payload":{"direction":"west"}}
```

```json
{"v":1,"type":"drop_key","seq":8,"requestId":"drop_key-8","payload":{}}
```

## Projection handling

View chunks are grouped by authoritative view sequence and rendered only after
all chunks arrive. Each completed view replaces the previous maze DOM in full.
The client does not merge a new view with previously visible cells, infer
missing passages, or retain an explored map. Maze dimensions, cells, objects,
player position, opponent visibility, inventory, vision duration, compass hint,
phase, and result all come from the server projection.

The session token is the only game-related value saved in browser storage. On
reload, the client sends that token in a `restore` intention and waits for a
fresh role-appropriate server projection. Position, inventory, effects, hints,
maze cells, and results are never restored from browser storage.

## Presentation states

Name selection, lobby, countdown, active play, pause, and match result use the
shared dark retro-arcade visual system. The fixed player status identifies the
player and labels inventory, remaining boosted-vision moves, compass direction,
and match phase. Modal overlays distinguish countdown, pause, and results.
Rejected movement produces a local wall-bump animation without revealing any
additional maze state. All player-facing copy and browser-generated errors are
Russian; protocol identifiers remain English.

Sound and supported vibration are enabled after the first pointer or keyboard
interaction. Both are progressive enhancements: unsupported devices continue
without an error.

Observer presentation and its read-only interaction boundary are documented in
`OBSERVER_UI.md`.