scxml 0.2.1

W3C SCXML statechart library — parse, validate, export, and simulate Harel statecharts. Framework-agnostic, WASM-ready, rkyv zero-copy.
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# Changelog

All notable changes to this project will be documented in this file.

The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/), and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).

## [0.2.1] - 2026-05-18

### Added

- WASM binding `resolve(json)` exposing the 0.2.0 `resolve()` function to JS/TS callers.

### Changed

- `quick-xml` 0.39.3 → 0.40.1 (migrated deprecated `Attribute::unescape_value()` to `normalized_value(XmlVersion::Implicit1_0)`).

## [0.2.0] - 2026-05-07

### Added

- `resolve()` → `ResolvedChart`: pre-computed effective transitions per state (own + inherited from ancestors), resolved initial children, sorted event catalog.
- `examples/compile_to_dispatcher.rs`: SCXML → Rust match dispatcher.

### Removed

- **Breaking**: `#[non_exhaustive]` removed from all model types. Enables exhaustiveness checking on enum matches and struct literal construction.

## [0.1.0] - 2026-04-17

First public release. A W3C SCXML statechart library for Rust that parses, validates, visualises, and simulates Harel statecharts. Not a runtime executor; compiled native types handle that.

### Repository

- Generic example workflows scrubbed of project-internal naming.
- README sections reorganised: added Installation, framework-agnostic note, FAQ.
- `types.d.ts` moved from repo root into `demo/` (it documents the WASM consumer surface).
- Cargo.toml metadata: `homepage`, `documentation` URLs added; keywords/categories tuned for discoverability.

### Parse

- W3C SCXML XML via quick-xml (`parse_xml`).
- JSON via serde (`parse_json`).
- Supports `<scxml>`, `<state>`, `<parallel>`, `<final>`, `<history>`, `<transition>`, `<onentry>`, `<onexit>`, `<datamodel>`, `<data>`.
- All W3C executable content elements stored as action descriptors (never evaluated):
  `<cancel>`, `<if>`/`<elseif>`/`<else>`, `<foreach>`, `<script>`, `<invoke>`.

### Model

- `Statechart`, `State` (Atomic, Compound, Parallel, Final, History), `Transition`, `Action` (Raise, Send, Assign, Log, Cancel, If, Foreach, Script, Invoke, Custom descriptors), `IfBranch`, `DataModel`, `DataItem`.
- Named guards (string references, not executable expressions).
- Extensions: `delay` (ISO 8601 duration) and `gnomes:quorum` attributes on transitions.
- `Display` impl for `Statechart`.
- rkyv `Archive`/`Serialize`/`Deserialize` derives on all model types (feature-gated).

### Validate

- **Structural**: duplicate IDs, unknown transition targets, initial state existence, final state constraints, compound/parallel region rules.
- **Liveness**: BFS reachability from initial state deadlock detection with inherited transition awareness (children of compound states with parent-level transitions are not flagged).

### Export

- SCXML XML (roundtrip-capable).
- DOT (Graphviz) with delay, quorum, and entry/exit action labels; deadline transitions
  rendered as dashed red lines.
- Mermaid stateDiagram-v2 with parallel region separators and compound state blocks.
- JSON via serde.
- Flat state/transition lists for frontend rendering.

### Simulate

- Lightweight test executor (`Simulator`) with event sending, guard evaluation (pass-all or custom closure), transition history, and reset.
- Not a production runtime; designed for testing workflow definitions before deployment.

### Build

- `StatechartBuilder` for ergonomic programmatic construction with compound, parallel, entry/exit actions, delay, quorum, and guard support.
- Consuming (`with_*`) and mutating (`set_*`) builder methods on `Transition`.

### Utilities

- **Diff**: structural comparison of two statecharts with path-qualified differences (changed, added, removed).
- **Stats**: `StatechartStats` with state counts by kind, transition counts (total/guarded/deadline), max nesting depth, data item count.
- **Sanitize**: `parse_untrusted()` with configurable input limits (`InputLimits`), DOCTYPE/ENTITY rejection, and identifier validation (`[a-zA-Z0-9_\-\.:]` only).

### WebAssembly

- `wasm-bindgen` bindings: `parseXml`, `parseJson`, `validate`, `toDot`, `toXml`, `flatten`, `xmlToDot` (feature-gated).
- TypeScript type declarations (`demo/types.d.ts`) for all JSON payloads.
- 306 KB optimised WASM binary.

### Demo

- Single-page HTML live editor with Graphviz rendering (viz.js), Mermaid export, and event simulation with state highlighting, guard toggle, and transition history.
- Four built-in examples in the demo: Simple, NPA, Settlement, Parallel.

### Testing

- 166 tests + 12 doc-tests across 9 test suites: unit, roundtrip, W3C conformance subset (15 tests), proptest invariants, rkyv roundtrip, edge cases, XState round-trip, and example file validation.

### Infrastructure

- **CI**: GitHub Actions with format, clippy, tests on Linux/macOS/Windows, benchmarks on 3 platforms, MSRV (1.85), security audit, docs build, coverage with auto-updated badge.
- **Benchmarks**: criterion benchmarks for parse, validate, export (DOT/XML/JSON), flatten, stats, diff, and rkyv (serialize/access/deserialize).
- **Examples**: NPA approval, document lifecycle, settlement, parallel compliance checks.