nucel-agent-opencode

OpenCode provider for the Nucel Agent SDK — an HTTP client for the OpenCode server.

Features

HTTP REST client — talks to opencode serve (no subprocess management)
Session management — POST /session then POST /session/{id}/prompt
Native session resume — resume() re-uses the existing OpenCode session ID
MCP support — OpenCode's native MCP integration is exposed to the agent
Budget enforcement — client-side cost guard before each query
Directory header — sets x-opencode-directory so the server scopes file operations to the right working directory
System prompt + model override — passed in the JSON body

How it works

OpenCode runs as a long-lived server (opencode serve, default port 4096). This provider:

Issues POST {base_url}/session to create a new session, returning a server session ID.

Issues POST {base_url}/session/{id}/prompt with:

{
  "parts": [{ "type": "text", "text": "<prompt>" }],
  "model":  { "modelID": "<model>" },   // optional
  "system": "<system prompt>"           // optional
}

Parses the response — concatenates all parts[].text entries with type == "text", falls back to the top-level text field if parts is empty.
Reads cost from the response's cost field.

For resume(session_id, …), the existing OpenCode session ID is reused instead of creating a new one.

Usage

[dependencies]
nucel-agent-sdk = "0.1"
tokio = { version = "1", features = ["full"] }

use nucel_agent_sdk::{OpencodeExecutor, AgentExecutor, SpawnConfig};
use std::path::Path;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Default: http://127.0.0.1:4096
    let executor = OpencodeExecutor::new();

    // Or point at a remote server:
    let executor = OpencodeExecutor::with_base_url("http://my-server:8080")
        .with_api_key("secret-token");

    let session = executor.spawn(
        Path::new("/my/repo"),
        "Fix the failing tests",
        &SpawnConfig {
            model: Some("claude-sonnet-4".into()),
            budget_usd: Some(5.0),
            system_prompt: Some("You are a senior Rust engineer.".into()),
            ..Default::default()
        },
    ).await?;

    // Follow-up query — reuses the same OpenCode session on the server.
    let resp = session.query("Now add more tests").await?;
    println!("{}", resp.content);

    session.close().await?;
    Ok(())
}

Capabilities

session_resume:     true   (native via session ID)
token_usage:        true
mcp_support:        true
autonomous_mode:    true
structured_output:  false

Requirements

OpenCode installed: npm install -g opencode
Server running: opencode serve (default http://127.0.0.1:4096)
(Optional) API key if your OpenCode server enforces auth

availability() always returns available: true for OpenCode — the executor can't easily probe the network here, so the reason field is used as a hint ("Run opencode serve to start server at …") rather than a hard error. Connection errors surface from spawn() / query() as AgentError::Provider.

Source

Repo: https://github.com/nucel-dev/agent-sdk
Docs: https://docs.rs/nucel-agent-opencode

License

Apache-2.0

nucel-agent-opencode 0.1.3