Struct HostBridge 

pub struct HostBridge { /* private fields */ }

A JSON-RPC 2.0 bridge to a host process over stdin/stdout.

The bridge sends requests to the host on stdout and receives responses on stdin. A background task reads stdin and dispatches responses to waiting callers by request ID. All stdout writes are serialized through a mutex to prevent interleaving.

Implementations

impl HostBridge

pub fn new() -> Self

Create a new bridge and spawn the stdin reader task.

Must be called within a tokio LocalSet (uses spawn_local for the stdin reader since it’s single-threaded).

pub fn from_parts( pending: Arc<Mutex<HashMap<u64, Sender<Value>>>>, cancelled: Arc<AtomicBool>, stdout_lock: Arc<Mutex<()>>, start_id: u64, ) -> Self

Create a bridge from pre-existing shared state.

Unlike new(), does not spawn a stdin reader — the caller is responsible for dispatching responses into pending. This is used by ACP mode which already has its own stdin reader.

pub fn set_session_id(&self, id: &str)

Set the ACP session ID for session-scoped notifications.

pub fn set_script_name(&self, name: &str)

Set the currently executing script name (without .harn suffix).

pub async fn call(&self, method: &str, params: Value) -> Result<Value, VmError>

Send a JSON-RPC request to the host and wait for the response. Times out after 5 minutes to prevent deadlocks.

pub fn notify(&self, method: &str, params: Value)

Send a JSON-RPC notification to the host (no response expected). Serialized through the stdout mutex to prevent interleaving.

pub fn is_cancelled(&self) -> bool

Check if the host has sent a cancel notification.

pub fn send_output(&self, text: &str)

Send an output notification (for log/print in bridge mode).

pub fn send_progress( &self, phase: &str, message: &str, progress: Option<i64>, total: Option<i64>, data: Option<Value>, )

Send a progress notification with optional numeric progress and structured data.

pub fn send_log(&self, level: &str, message: &str, fields: Option<Value>)

Send a structured log notification.

pub fn send_call_start( &self, call_id: &str, call_type: &str, name: &str, metadata: Value, )

Send a session/update with call_start — signals the beginning of an LLM call, tool call, or builtin call for observability.

pub fn send_call_progress( &self, call_id: &str, delta: &str, accumulated_tokens: u64, )

Send a session/update with call_progress — a streaming token delta from an in-flight LLM call.

pub fn send_call_end( &self, call_id: &str, call_type: &str, name: &str, duration_ms: u64, status: &str, metadata: Value, )

Send a session/update with call_end — signals completion of a call.