# Entropyk Web UI

Visual canvas builder for Entropyk thermodynamic cycles.

The UI emits the same `ScenarioConfig` JSON as the CLI
(`crates/cli/src/config.rs`). Physics always runs through
`entropyk_cli::run::simulate_from_json` via the Axum `ui-server`.

## Prerequisites

- Node.js 18+ and npm
- The Rust API server running (see below)

## Setup

### 1. Start the Rust API server

From the project root:

```bash
cargo run -p entropyk-demo --bin ui-server
# → http://localhost:3030
```

Endpoints:
- `GET  /api/health`
- `GET  /api/components`
- `POST /api/simulate`
- `GET  /api/mollier?fluid=R134a`

### 2. Start the Next.js dev server

```bash
cd apps/web
npm install
npm run dev
# → http://localhost:3000
```

By default the frontend proxies `/api/entropyk/*` to `http://localhost:3030/api/*`
(see `next.config.mjs`). To point at a different API, set:

```bash
ENTROPYK_API_URL=http://my-host:3030 npm run dev
```

## Usage

1. Drag components from the left palette onto the canvas.
2. Connect ports by dragging from one handle to another.
3. Select a node to edit its parameters in the right panel.
4. Pick the fluid and backend in the top bar.
5. Click **Solve cycle** — the result panel shows COP, edge states and a P-h diagram.
6. **Load** drops in a CLI example from the picker; **Import JSON** loads any CLI config.
7. **Multi-run** sweeps parameters (fluid, UA, …) and solves cases in parallel.

## Architecture

```
Browser (Next.js)         Rust API (Axum ui-server :3030)
  React Flow canvas   →   POST /api/simulate
  Zustand store             → simulate_from_json() (CLI engine)
  Recharts P-h diagram  ←   SimulationResult JSON
```

Anything buildable in the UI can also be run with:

```bash
cargo run -p entropyk-cli -- run path/to/config.json
```

## Deprecated surfaces

- `ui/` at the repo root — legacy static HTML; calls removed `/api/calculate`. Do not use.
- `tools/circuit-builder-ui` — alternate HTML builder; prefer `apps/web`.