Reference

Conventions

Axes and units: Y-up, right-handed. Lengths in meters, time in seconds, mass in kilograms, angles in degrees (Transform.rotation is XYZ Euler degrees). Every physical field's unit is in its schema (x-unit).
Documents (.scene, .prefab) are canonical JSON: a flat records map keyed by short IDs. Defaults are omitted; key order is the formatter's (ara fmt), never by hand.
IDs: <prefix>_<base32>: entities e_8b21, scenes sc_…, prefabs pf_…. An entity inside a prefab instance is addressed through it: e_4f9a/e_m4tz.
References: @path#id (@prefabs/crate.prefab#pf_crate001). Either half repairs the other when it goes stale.
Edit with commands, not raw file surgery, for hierarchy, prefabs and graphs: ara_apply / ara do. Batches are atomic; mint symbolic IDs with "as": "$crate" and use them in later calls. dryRun previews the diff.
Agent turns: every change is a transaction with a why. Agent changes apply immediately. History, per-turn undo, overwrite notices and active-field gesture safety keep collaboration visible.
Sessions: begin one (session.begin) and pass its handle to every call. Scopes limit what a session may do.
Find things: schema.search for components and commands, docs.search for these pages, query for entities, logs for diagnostics (stable ARA#### codes with fixes).