kiln/CLAUDE.md

# CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

## Project

`viberogue` is a ZZT-inspired game-making system written in Rust (edition 2024). The goal is a system where players can create games using a scripting language, similar to the classic DOS game ZZT. It uses **Rhai** for scripting (WASM-compatible, sandboxed, pure Rust).

## Code style

- Add `///` rustdoc comments to every `pub` type, field, and function. The user reads rustdoc in their IDE to understand the code while making changes.
- Add inline `//` comments inside non-trivial function bodies to explain the *why* of each logical step — especially in `update` loops, rendering math, and conversion logic.
- Keep comments accurate: update them when the code they describe changes.

## Commands

```bash
cargo build          # compile
cargo run            # build and run (loads maps/start.toml)
cargo test           # run all tests
cargo test <name>    # run a single test by name (substring match)
cargo clippy         # lint
cargo fmt            # format
```

## Architecture

The game is a single Rust binary using **eframe 0.33 / egui 0.33** for the GUI. eframe drives a retained-mode UI: the `App::update` method is called every frame and is responsible for both drawing and responding to input.

`update` is structured in two panels:
- `egui::TopBottomPanel::top` — menu bar (File → Exit)
- `egui::CentralPanel::default` — game viewport; rendered with `ui.painter()`

### Modules

**`src/game.rs`** — all core game types:
- `Glyph` (`Copy`) — per-cell visual: `ch: char`, `fg/bg: Color32`. `Glyph::player()` is the only constructor used at runtime (colors for board tiles come from the map file).
- `Element` — behavior: `passable: bool` (future: `opaque`, etc.)
- `Board` — the complete game unit (ZZT-style "board"): `width`, `height`, `elements: Vec<Element>` (behavior palette), `cells: Vec<(Glyph, usize)>` (row-major; usize indexes into `elements`), `player: Player`, `objects: Vec<ObjectDef>`, `portals: Vec<PortalDef>`. `cells` is `pub(crate)`.
- `Player` — `x: i32, y: i32`
- `ObjectDef` / `PortalDef` — parsed from map files, stored on Board; not yet runtime-wired
- `GameState` — holds `board: Board`; `try_move(dx, dy)` checks passability before moving the player

**`src/map_file.rs`** — map file loading:
- `MapFile` and friends — serde `Deserialize` types for TOML map files
- `impl From<MapFile> for Board` — converts a parsed file into a ready-to-use `Board`
- `pub fn load(path: &str) -> Result<Board, Box<dyn std::error::Error>>` — reads and converts a `.toml` map file

**`src/main.rs`** — app entry point:
- Loads `maps/start.toml` before creating the window (so board dimensions drive window size)
- Window min-size = `board.width * CELL_W + 2*PANEL_MARGIN` × `board.height * CELL_H + MENU_H + 2*PANEL_MARGIN`
- Board is centered in the CentralPanel when the window is larger than minimum
- `draw_glyph(painter, origin, x, y, glyph)` draws one cell: filled rect (bg) + monospace char (fg)
- Player is rendered on top of the board using `Glyph::player()`
- Arrow key input handled via `ctx.input(|i| ...)` before panel rendering

### Map file format (`maps/*.toml`)

XPM-inspired: a `[palette]` maps single characters to `(Glyph, Element)` definitions; `[grid] content` is a TOML multi-line string where each character indexes the palette.

```toml
[map]
name = "Room Name"
width = 60
height = 25
player_start = [30, 12]

[palette]
" " = { passable = true,  ch = " ", fg = "#000000", bg = "#000000" }
"#" = { passable = false, ch = "#", fg = "#808080", bg = "#606060" }

[grid]
content = """
############################################################
#                                                          #
############################################################
"""

[[objects]]          # optional; parsed but not yet runtime-wired
x = 10
y = 5
script = """
  on_touch(|| { send_message("open"); });
"""

[[portals]]          # optional; parsed but not yet runtime-wired
x = 59
y = 12
target_map = "cave"
target_entry = "west_door"
```

Colors are `"#RRGGBB"` hex strings. `player_start` is a header field — the player is not a board cell. The grid multi-line string's leading newline is trimmed by TOML; trailing newline is handled correctly by `str::lines()`.

### Key design decisions

- **`cells: Vec<(Glyph, usize)>`** — the `usize` element index is intentionally an anonymous tuple field; it only has meaning relative to a specific `Board`'s `elements` palette and cannot be misused as a standalone value.
- **`Board` is the complete unit** — grid, player, objects, and portals all live on `Board`, matching how ZZT treats a "board". No separate wrapper struct.
- **Glyph (visual) and Element (behavior) are decoupled** — each cell has its own `Glyph` (so colors can vary per-cell, e.g. fire flickering) but shares `Element` definitions from the palette.
- **File loading happens in `main()`** before the window is created, so board dimensions are available for window sizing.

eframe runs on its own event loop thread; do not assume single-threaded execution.