openworldformat (crates.io)

The Open World Format's Rust reference: the world document (types and edits), the session fold (log, branches, state), and the ext-physics extension's executable half — one serde-only crate, no Bevy, no async, no sockets. The same code that implemented the format in LocalGPT since its origin, extracted into the format's own home.

cargo add openworldformat        # or, from this checkout:
cargo add --path rust openworldformat

use openworldformat::{WorldManifest, OpLogEntry, fold_log, fold_path};

let manifest: WorldManifest = serde_json::from_str(&manifest_text)?;
let entries: Vec<OpLogEntry> = log_text.lines()
    .filter(|l| !l.trim().is_empty())
    .map(serde_json::from_str).collect::<Result<_, _>>()?;

let doc = fold_log(&manifest.as_base()?, &entries)?;   // the world at head
let (doc, path) = fold_path(&base, &entries, Some("e3"))?; // or at any tip

openworldformat::state::fold_state folds the game state over state.json (save games are base + declaration + a player's log); openworldformat::physics carries the extension's deterministic reference solver, trajectory write/fold, and the conformance outcome runner; the schema feature generates world.schema.json.

Provenance and the plan

Extracted from LocalGPT's world-types, world-sync and world-physics — not rewritten: in one language, two hand-written type layers would only be drift risk. LocalGPT remains the app-side consumer with its own copies until it's quiet enough to flip them to re-export shims over this crate; until then, both sides generate the same world.schema.json, and the snapshot test in each repository fails when they disagree. The schema's generation_tool default is a pinned literal for the same reason: a published schema must not churn with a generating crate's version.

Two cross-implementation fixes landed with the extraction, applied on both sides: entries may omit author (the spec's own example logs do; the JS fold always read them), and the folded schema is version-independent.

Test

cargo test                      # unit + conformance + examples + physics outcomes
cargo test --features schema    # + the schema snapshot (both generators agree)

CI runs both, alongside the js and python jobs — three references, one set of worlds and outcome assertions.

Apache-2.0.