docs: updated README

ui/README.md

@@ -1,2 +1,48 @@
-# leios-visual
-Visualizations for Leios data.
+# Rust Simulation UI - Web App
+
+This UI web app is designed to read and display simulation traces generated by
+the `sim-rs` project.
+
+## Prerequisites
+
+Before you can run the UI, ensure you have the following installed:
+
+- [Bun](https://bun.sh/) - A fast JavaScript runtime.
+
+## Setup Instructions
+
+1. **Install Bun**
+
+   Follow the instructions on the [Bun website](https://bun.sh/) to install Bun
+   on your system.
+
+2. **Generate a Trace**
+
+   Before running the UI, you need to generate a trace using the `sim-rs`
+   simulation. Navigate to the `sim-rs` directory and run the following command:
+
+   ```bash
+   cargo run --release test_data/thousand.toml output/messages.jsonl -s 30
+   ```
+
+   This command will generate a trace file at `output/messages.jsonl`.
+
+3. **Run the UI**
+
+   With Bun installed and the trace generated, navigate to the UI project
+   directory and start the development server:
+
+   ```bash
+   bun dev
+   ```
+
+   This will launch the simulation in your browser.
+
+## Additional Information
+
+- Ensure that the path to the trace file (`output/messages.jsonl`) is correctly
+  set in the UI project. This is typically defined in a utility file such as
+  `ui/src/app/api/utils.ts`.
+
+- If you encounter any issues, check the console for error messages and ensure
+  all dependencies are correctly installed.