# Oxidizer — Rust Specialist LoRA

Adapter codename: `oxidizer`
Agent: `build-rust`
Base model: Qwen/Qwen3.5-27B

## Objective

Teach the model Rust-idiomatic code generation aligned with the build-rust agent's
system prompt constraints. The adapter should internalize:

- `Result<T, E>` everywhere, no `unwrap()` in library code
- `thiserror` for libs, `anyhow` for binaries
- `tokio` 1.x async, `tracing` for logging
- Edition 2024, no `Box<dyn Error>`, no unjustified `unsafe`
- cargo fmt → clippy → test verification cycle
- Workspace-aware Cargo.toml patterns

## Data Sources

### Session extraction (~150–250 examples)

Classify from opencode `build` sessions by:
- File paths containing `.rs`, `Cargo.toml`, `Cargo.lock`
- Bash commands: `cargo build`, `cargo test`, `cargo clippy`, `cargo fmt`, `cargo add`
- Compiler output patterns: `error[E`, `warning:`, `rustc`
- Tool calls editing `.rs` files

### Git repo mining (~100–200 examples)

Target repos:
- `madcat-os/tengu` — Rust mesh daemon, async networking, MQTT
- `madcat-os/madcat-core` — core library, data structures
- `madcat-os/madcat-tts` — TTS pipeline, audio processing
- Any other `Cargo.toml`-rooted repos in madcat-os org

Extract patterns:
- Bug fixes with before/after (error diagnosis training)
- Refactors (code improvement patterns)
- New feature implementations (scaffold → impl → test)
- Dependency additions with rationale

### Synthetic (~50–100 examples)

Generate for gaps:
- Lifetime annotation scenarios
- Trait object vs generics decisions
- `Pin<Box<dyn Future>>` patterns
- Cross-crate error propagation
- Workspace dependency management
- `#[derive]` and proc macro usage

## Example Format

```json
{
  "messages": [
    {
      "role": "system",
      "content": "<build-rust agent system prompt>"
    },
    {
      "role": "user",
      "content": "Add error handling to the MQTT connection retry loop in src/mqtt.rs"
    },
    {
      "role": "assistant",
      "content": null,
      "tool_calls": [
        {
          "type": "function",
          "function": {
            "name": "read",
            "arguments": {"filePath": "/path/to/src/mqtt.rs"}
          }
        }
      ]
    },
    {
      "role": "tool",
      "content": "<file contents>"
    },
    {
      "role": "assistant",
      "content": null,
      "tool_calls": [
        {
          "type": "function",
          "function": {
            "name": "edit",
            "arguments": {
              "filePath": "/path/to/src/mqtt.rs",
              "oldString": "<original code>",
              "newString": "<fixed code with Result<T, E>>"
            }
          }
        }
      ]
    },
    {
      "role": "tool",
      "content": "Edit applied successfully"
    },
    {
      "role": "assistant",
      "content": null,
      "tool_calls": [
        {
          "type": "function",
          "function": {
            "name": "bash",
            "arguments": {"command": "cargo clippy --all-targets -- -D warnings"}
          }
        }
      ]
    },
    {
      "role": "tool",
      "content": "<clippy output — clean>"
    },
    {
      "role": "assistant",
      "content": "Error handling added. Connection retry now returns `Result<MqttClient, ConnectionError>` with exponential backoff. Clippy clean."
    }
  ]
}
```

## Evaluation Criteria

1. Generated Rust code compiles with `cargo build`
2. No `unwrap()` in non-test code
3. Uses `?` propagation, not manual match-on-error
4. Correct lifetime annotations (no unnecessary `'static`)
5. `cargo clippy -- -D warnings` passes
6. Appropriate crate recommendations (tokio, serde, tracing, etc.)
7. Tool call sequence: read → edit → verify (fmt/clippy/test)

## Training Config Overrides

```python
MAX_SEQ = 8192   # Rust files can be long
LR      = 5e-5   # Lower LR for code — less style drift from base
```

## Estimated Size

- 300–500 examples total
- ~2M tokens at avg 4K tokens/example
- Training time: ~2–3 hrs on H100
- Adapter size: ~305 MB
