> ## Documentation Index
> Fetch the complete documentation index at: https://docs.eucaengine.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Changelog

> What's new in Euca — highlights by area. Mirrors the repo CHANGELOG; the current workspace version is 1.1.0.

Highlights from the engine changelog, grouped by area and linked to the docs. The current workspace
version is **1.1.0** (`Cargo.toml`).

## 1.1.0 — current

### Unified Editor & Data-Driven Levels

* **`euca-studio` — one unified editor.** A single app that discovers every project, lets you select one
  in-editor, edit its scene as data, and press **Play** to run it. `cargo run -p euca-studio`. The
  game-engine / experience face. [→](/concepts/two-faces)
* **Headless host.** `cargo run -p euca-studio -- --headless [project_id]` serves a project's world over the
  agent HTTP API on `:3917` with no window — it runs the game's full per-tick logic (`game.step`), replacing
  the old fixed-schedule example server. [→](/systems/hosting-deployment)
* **Data-driven levels via generic reflection.** Any `#[derive(Reflect)]` component survives a save↔load
  round-trip, so the host loads a project's level and the editor edits the same scene the game plays.

### World-model & evaluation substrate

* **`euca-online` — interactive world substrate.** `OnlineWorld` exposes
  [`observe` / `peek` / `step`](/concepts/query-verbs), with the tested **`peek == step`** invariant.
* **Regret grading.** Prequential [regret in nats](/evaluation/overview) against the known generative
  distribution; a perfect predictor scores 0.
* **`fork_peek` counterfactual branching** — clone mid-episode; the unchanged remainder stays
  bit-identical. [→](/concepts/forks)
* **`euca-dataset` — world-model data engine.** Object-centric state/action/event extraction consuming
  ground-truth segmentation/depth channels. [→](/systems/datasets)
* **Editor Evaluation mode** — a ground-truth inspector that makes observe/peek/fork/regret visible.

### Unified rule engine

* **`euca-rule` — pure-data Rule DSL.** One `Rule` (condition + declared distribution + effects) drives
  MOBA, agent, editor, and dataset paths. [→](/concepts/rules-as-data)
* **Single-RNG CI gate** — one deterministic RNG source across the rule/online path.

### Physics

* **Iterated SI solver + rotation-aware narrow-phase**, **convex colliders**, **static triangle meshes**,
  **compound colliders via convex decomposition**, and **reduced-coordinate articulation (Phases 1–4)**.
  [→](/concepts/engine-internals)

### ECS scale

* **Chunked parallel queries** — the 5-system pipeline runs \~11.3× faster at 1M entities (2.7 ms vs
  30.6 ms on M4 Pro). **`spawn_batch`** (\~16×). **`Commands`** deferred mutation. [→](/concepts/performance)

### Rendering

* **Velocity pass wired** (TAA + motion blur no longer no-ops), **real per-frame frustum culling + LOD**,
  a **post-process Sobel outline**, and **GPU-timing** in the profiler. [→](/concepts/engine-internals)

### Asset pipeline

* **AI-3D-gen world-model decoupling + provenance** — generated appearance provably never touches the
  hashed `state_digest`. **Cooked-asset LOD pipeline** with PNG-compressed textures. [→](/systems/asset-generation)

### RHI & native Metal

* **`euca-rhi` — `RenderDevice` trait** decoupling the renderer from any GPU API, plus a **native Metal
  backend** (Apple Silicon).

### Foundations

The base the above builds on: the build/play/experiment HTTP surface, the gameplay layer (with
MOBA and a GTA-like vertical slice shipping as example games), the forward PBR renderer, and the
physics solver.

<Note>
  This is a curated summary. Capability pages carry the current, code-verified detail; the
  [API reference](/api-reference/introduction) is a hand-maintained OpenAPI snapshot (the
  generator was retired) — `GET /schema` on the running server is the always-current source.
</Note>