# BREP_app
The BREP CAD application: one Rust egui/wgpu codebase for native desktop and
WebAssembly. Package `BREP_app`, library `brep_app`, version 0.6.0.
The 3D engine is `BREP_render`; geometry comes from `BREP_kernel`.
## Build and run
```sh
cargo install BREP_app
brep-app
brep-app --mcp
```
From a source checkout, `cargo build --release` in this crate builds the same
binary, and `cargo build --release --target x86_64-pc-windows-gnu` cross-builds
it for Windows (the GNU target and the mingw-w64 linker are needed). The
crate's floor is `rust-version = "1.92"`, which is what eframe/egui 0.35
declare. The WebAssembly build is made with `wasm-pack` from a source checkout.
`--mcp` serves the visible native app over loopback HTTP as a
[Model Context Protocol](https://modelcontextprotocol.io) server, through
[`BREP_mcp_core`](https://crates.io/crates/BREP_mcp_core), so an agent can drive
the same window a person is using.
## Feature flags
- `mcp` (default, native only) — the embedded MCP server behind `--mcp`.
- `scripting` (default) — scripts in the application, on the Boa interpreter
from [`BREP_script_core`](https://crates.io/crates/BREP_script_core), native
and wasm.
- `automation` — the command registry, queue and virtual pointer an automation
host drives the application through; `mcp` turns it on.
## Architecture
| `src/app.rs` | eframe shell, document lifecycle and action dispatch |
| `src/document.rs` | Open documents, each with one `EngineState` |
| `src/viewport.rs`, `src/viewport/` | Offscreen 3D render, egui composition, input and labels |
| `src/panels/` | History, scene, sketches, files, assemblies, PMI, harness and other panels |
| `src/form.rs`, `src/form_view.rs` | Shared schema fields and complete forms |
| `src/workbench/` | Six definitions, feature predicates, contributed actions and panel claims |
| `src/store.rs` | Native filesystem and browser persistence |
| `src/recovery.rs` | Dirty-document autosave and startup recovery |
| `src/automation/` | Command/state/hit-key registries, queue and virtual input |
| `src/mcp.rs` | Native attached-window server host |
`EngineState` owns the editable history, undo, scene, camera, selections and
editing modes. Panels borrow it and apply intents; they do not keep another
feature list. Native and browser runners evaluate history off the UI thread.
History has a tree and a separate form. The same form view serves features,
assembly constraints, PMI annotations and dialog screenshots. Workbenches filter
creation and panel/action visibility; existing histories remain editable.
PMI additionally activates captured views and restores modeling display state.
The viewport renders into an app-owned texture on eframe's wgpu device. A paint
callback composites it into the egui frame. Scene-row hover and viewport hover
use the same engine highlighting. Glyphs are SVG artwork from the asset catalogue.
## Files and persistence
Open, Save As, Import and Export use the shared in-app file explorer. Desktop
storage uses real filesystem paths; browser storage uses an IndexedDB mirror
with upload/download bridging. Saved document state and user settings are separate.
Startup offers dirty-document recovery instead of silently reopening an old session.
## Help and distribution
The in-app help is a static site generated from the user documentation by
[`BREP_docs`](https://crates.io/crates/BREP_docs); it closes with a Licences
section (the project licence, the third-party notices, and an inventory of
every crate the application ships, with the font notices that must accompany
the embedded fonts).
The native default `mcp` feature embeds `BREP_mcp_core`; the wasm build uses
its automation layer without the native server dependencies. The crate ships
`LICENSE.md` (the Autodrop3d licence, `license-file` in the manifest) and
`THIRD-PARTY-NOTICES.md`, which covers the four bundled font faces; a native
binary distributed on its own needs both files beside it.