# Copilot Instructions

## What this repository is

A **FoundryVTT content module** for the MGT2 (Mongoose Traveller 2nd edition) system. It is a pure data module — there is no JavaScript, CSS, or HTML. All content is in **French**.

Compatible with FoundryVTT v11–v13, requiring the `mgt2` game system.

## Architecture

```
module.json       ← FoundryVTT module manifest (single source of truth for module metadata)
packs/            ← Compendium packs stored as LevelDB databases (binary .ldb files)
assets/icons/     ← SVG icons, named in French (with accented characters)
```

### Packs

Each subdirectory under `packs/` is a LevelDB database managed by FoundryVTT. **Never edit `.ldb` files directly** — pack content is modified through the FoundryVTT UI and exported via its built-in compendium tools.

Current packs and their document types:

| Pack folder | Label | Type |
|---|---|---|
| `armures` | Armures | Item |
| `armes` | Armes | Item |
| `competences` | Compétences | Item |
| `carrieres` | Carrières | Item |
| `talents-psioniques` | Talents psioniques | Item |
| `maladie-poison-and-blessure` | Maladie, Poison & Blessure | Item |
| `equipement` | Équipement | Item |
| `ordinateur` | Ordinateur | Item |
| `contenant-sac-coffre` | Contenant (sac, coffre) | Item |
| `espece` | Espèce | Item |
| `objet` | Objets | Item |
| `journal` | Journal Psioniques | JournalEntry |

> The folders `arme`, `carriere`, and `talent-psy` appear to be legacy/deprecated predecessors of `armes`, `carrieres`, and `talents-psioniques`.

## JavaScript module architecture

The module now includes a `/commerce` chat command that opens a trade workflow dialog. Entry point: `scripts/commerce.js` (ES module, declared under `"esmodules"` in `module.json`).

```
scripts/
  commerce.js          ← entry point; registers /commerce via Hooks.on("chatMessage")
  CommerceDialog.js    ← FormApplication with 3 tabs (passengers / cargo / speculative trade)
  tradeHelper.js       ← business logic: dice rolls (Foundry Roll API), price calculations
  uwpParser.js         ← parses UWP strings (e.g. A788899-C) → trade codes (Ag, In, Ri…)
  data/
    tradeTables.js     ← all data tables: goods (D66), passenger/cargo traffic, prices
templates/
  commerce-dialog.hbs  ← Handlebars template for the dialog (3-tab form)
  commerce-result.hbs  ← Handlebars template for the chat result card
styles/
  commerce.css         ← dialog and chat card styles
```

### Key patterns
- **Dice rolls** use `await new Roll(formula).evaluate()` — always async.
- **UWP parsing** via `parseUWP(uwp, zone)` in `uwpParser.js`; trade codes are derived automatically.
- **Trade code modifiers**: only the highest applicable modifier from each column (buy/sell) is used per the rules (not cumulative).
- **Goods table (D66)**: all 30 entries (D66 11–66) are implemented in `tradeTables.js`, including illegal goods (D66 61–65) and the free-form Exotics entry (D66 66). Illegal goods have `illegal: true` and are only surfaced when `blackMarket: true` is passed to `findAvailableGoods()`.
- **Template helpers** (`formatCredits`, `join`, `gt`, `gte`, `eq`) are registered lazily in `CommerceDialog.js` on first use.
- **FormApplication tabs** use the built-in Foundry tab system (`navSelector`, `contentSelector`, `initial`).

## Key conventions

### module.json

Every pack **must** be declared in `module.json` under `"packs"`. The standard ownership for all packs is:

```json
"ownership": {
  "PLAYER": "OBSERVER",
  "ASSISTANT": "OWNER"
}
```

All packs use `"system": "mgt2"`.

When adding a new pack, add its entry to `module.json` **and** create the corresponding directory under `packs/` (FoundryVTT will initialise the LevelDB files on first use).

### Icons

- Stored in `assets/icons/` as SVG files
- File names are in French and may contain accented characters (e.g., `mécanique.svg`, `éclaireur.svg`)
- Referenced in item data as relative module paths, e.g.:  
  `modules/mgt2-compendium-amiral-denisov/assets/icons/<name>.svg`

### Version bumps

Version is defined once in `module.json` under `"version"`. There is no separate changelog file.