# Writing and symbol data

Milestone 4 stores what a player wrote without deciding what that writing does
to an Age. Milestone 5 owns grammar validation, symbol interaction, instability,
and translation into biome, noise, dimension-type, and other world-generation
configuration.

## Symbol catalog

The authoritative server catalog loads JSON resources from
`data/<namespace>/rivencraft/symbols/<path>.json`. The resource ID is the
symbol ID. For example, `data/rivencraft/rivencraft/symbols/terrain/standard.json`
defines `rivencraft:terrain/standard`.

Schema version 1 contains display metadata only:

```json
{
  "schema_version": 1,
  "name": "symbol.rivencraft.terrain.standard",
  "description": "symbol.rivencraft.terrain.standard.description",
  "category": "rivencraft:terrain"
}
```

`name` and `description` are translation keys, not arbitrary formatted text or
executable behavior. `category` is a namespaced organizational identifier.
Invalid definitions are logged and excluded by the server. Menus and future
page synchronization must obtain resolved display metadata from the server;
clients never make a symbol valid by naming it.

Rivencraft ships a small catalog covering terrain, biomes, lighting, weather,
celestial behavior, and features. It exists to exercise the complete writing
workflow before Milestone 5 implements the full legacy grammar.

## Persistent writing

`SymbolReference` stores only a namespaced symbol ID. `WritingEntry` is either
a symbol reference or a baseline link-panel marker. `OrderedWriting` retains up
to 256 entries in exact player-authored order. All three contracts have both
persistent codecs and bounded network codecs.

Removing a data pack never removes its IDs from saved writing. A missing ID is
resolved as client-safe **Unresolved Symbol** display metadata while retaining
the original namespaced ID for diagnostics and later restoration. This is
deliberately different from treating an unknown symbol as valid grammar.

## Pages

The single stackable `rivencraft:page` item has a bounded, persistent
`rivencraft:page_content` component. Its explicit states are blank, symbol,
unresolved symbol, and baseline link panel. Symbol and unresolved-symbol pages
retain their namespaced symbol reference; unresolved pages can be inspected and
removed but are rejected as usable writing until their data pack returns.

Only server-side writing operations may turn a blank page into a known symbol
page or link panel. The shared `PageItem` creation and validation gates reject
new pages for identifiers absent from the server catalog. Later Writing Desk
and Book Binder packets must call these gates rather than accepting page
contents supplied by a client.

The item model uses server-assigned custom-model data derived from the symbol
identifier. Built-in pages reproduce Mystcraft Legacy's four-word poem
composition from its page background and symbol-component sheet. Data-pack
symbols without a bundled resource-pack model use the legacy question-mark
fallback while keeping their real identifier and display metadata.