# @push.rocks/smartrust

> A type-safe bridge between JavaScript engines and Rust binaries.

Latest version **2.3.0** (published 2026-09-20) · MIT license · 0 weekly downloads

## Install

```sh
npm install @push.rocks/smartrust
pnpm add @push.rocks/smartrust
yarn add @push.rocks/smartrust
bun add @push.rocks/smartrust
```

## Health

**Score 70/100 (B)** — status: active.

Positive: has types; esm support; no vulnerabilities; recently updated; high maintenance score; high quality score.

Warnings: low downloads.

## Facts

| | |
|---|---|
| Version | 2.3.0 |
| Published | 2026-09-20 |
| First published | 2026-02-10 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | bundled |
| Module format | ESM + CommonJS |
| Dependencies | 1 |
| Unpacked size | 360.4 KB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| Author | Task Venture Capital GmbH |
| Maintainers | lossless |
| Keywords | rust, typescript, ipc, bridge, stdio, socket, binary, transport |

## Links

- npm: https://www.npmjs.com/package/@push.rocks/smartrust
- Repository: https://code.foss.global/push.rocks/smartrust
- Homepage: https://code.foss.global/push.rocks/smartrust#readme
- Issues: https://code.foss.global/push.rocks/smartrust/issues
- npm.io page: https://npm.io/package/@push.rocks/smartrust

## Dependencies (1)

- [@push.rocks/smartpath](https://npm.io/package/@push.rocks/smartpath.md) ^6.0.0

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## Recent versions

- 2.3.0 (latest) — 2026-09-20
- 2.2.0 — 2026-09-15
- 2.1.0 — 2026-09-14
- 2.0.0 — 2026-09-05
- 1.9.1 — 2026-09-05
- 1.9.0 — 2026-08-28
- 1.8.0 — 2026-08-22
- 1.7.1 — 2026-08-22
- 1.7.0 — 2026-08-09
- 1.6.1 — 2026-08-02
- 1.6.0 — 2026-08-02
- 1.5.0 — 2026-07-28
- 1.4.1 — 2026-07-28
- 1.4.0 — 2026-04-30
- 1.3.2 — 2026-03-14
- … 7 more at https://npm.io/package/@push.rocks/smartrust/versions

## README

# @push.rocks/smartrust

A type-safe, production-ready bridge between TypeScript and Rust binaries — with support for **stdio** (child process) and **socket** (Unix socket / Windows named pipe) transports, request/response, streaming, and event patterns.

## Issue Reporting and Security

For reporting bugs, issues, or security vulnerabilities, please visit [community.foss.global/](https://community.foss.global/). This is the central community hub for all issue reporting. Developers who sign and comply with our contribution agreement and go through identification can also get a [code.foss.global/](https://code.foss.global/) account to submit Pull Requests directly.

## Install 📦

```bash
pnpm add @push.rocks/smartrust
```

## Overview 🔭

`@push.rocks/smartrust` provides a complete bridge for TypeScript applications that need to communicate with Rust binaries. It handles the entire lifecycle — binary discovery, process spawning **or socket connection**, request/response correlation, **streaming responses**, event pub/sub, and graceful shutdown — so you can focus on your command definitions instead of IPC plumbing.

### Two Transport Modes 🔌

| Mode | Method | Use Case |
|------|--------|----------|
| **Stdio** | `bridge.spawn()` | Spawn the Rust binary as a child process. Communicate via stdin/stdout. |
| **Socket** | `bridge.connect(path)` | Connect to an **already-running** Rust daemon via Unix socket or Windows named pipe. |

The JSON protocol is identical in both modes — only the transport layer changes. Socket mode enables use cases where the Rust binary runs as a **privileged system service** (e.g., a VPN daemon needing root for TUN devices, a network proxy binding to privileged ports) while the TypeScript app connects to it unprivileged.

### Why? 🤔

If you're integrating Rust into a Node.js project, you'll inevitably need:
- A way to **find** the compiled Rust binary across different environments (dev, CI, production, platform packages)
- A way to **spawn it** or **connect to it** and establish reliable two-way communication
- **Type-safe** request/response patterns with proper error handling
- **Streaming responses** for progressive data processing, log tailing, or chunked transfers
- **Event streaming** from Rust to TypeScript
- **Graceful lifecycle management** (ready detection, clean shutdown, auto-reconnection)

`smartrust` wraps all of this into a clean API: `RustBridge`, `RustBinaryLocator`, `StreamingResponse`, and pluggable transports.

## Usage 🚀

### The IPC Protocol

`smartrust` uses a simple, newline-delimited JSON protocol:

| Direction | Format | Description |
|-----------|--------|-------------|
| **TS → Rust** (Request) | `{"id": "req_1", "method": "start", "params": {...}}` | Command with unique ID |
| **Rust → TS** (Response) | `{"id": "req_1", "success": true, "result": {...}}` | Final response correlated by ID |
| **Rust → TS** (Error) | `{"id": "req_1", "success": false, "error": "msg", "errorCode": "EAPP_INVALID"}` | Error correlated by ID; `errorCode` is optional |
| **Rust → TS** (Stream Chunk) | `{"id": "req_1", "stream": true, "data": {...}}` | Intermediate chunk (zero or more) |
| **Rust → TS** (Event) | `{"event": "ready", "data": {...}}` | Unsolicited event (no ID) |

This protocol works identically over stdio and socket transports. Your Rust binary reads JSON lines from one end and writes JSON lines to the other. That's it.

### Defining Your Commands

Start by defining a type map of commands your Rust binary supports:

```typescript
import { RustBridge } from '@push.rocks/smartrust';

// Define your command types
type TMyCommands = {
  start:      { params: { port: number; host: string }; result: { pid: number } };
  stop:       { params: {};                             result: void };
  getMetrics: { params: {};                             result: { connections: number; uptime: number } };
  reload:     { params: { configPath: string };         result: void };
};
```

### Stdio Mode — Spawn a Child Process

This is the classic mode. The bridge spawns the Rust binary and communicates via stdin/stdout:

```typescript
const bridge = new RustBridge<TMyCommands>({
  binaryName: 'my-rust-server',
  envVarName: 'MY_SERVER_BINARY',             // optional: env var override
  platformPackagePrefix: '@myorg/my-server',  // optional: platform npm packages
});

// Spawn the binary and wait for it to signal readiness
const ok = await bridge.spawn();
if (!ok) {
  console.error('Failed to start Rust binary');
  process.exit(1);
}

// Send type-safe commands — params and return types are inferred!
const { pid } = await bridge.sendCommand('start', { port: 8080, host: '0.0.0.0' });
console.log(`Server started with PID ${pid}`);

const metrics = await bridge.sendCommand('getMetrics', {});
console.log(`Active connections: ${metrics.connections}`);

// Listen for events from Rust
bridge.on('management:configChanged', (data) => {
  console.log('Config was changed:', data);
});

// Confirmed shutdown (SIGTERM → SIGKILL after 5s)
await bridge.terminate();
```

Stdio children can inherit caller-owned file descriptors. Values map in order
starting at child fd 3; the source descriptors remain owned by the caller and
are never closed by Smartrust:

```typescript
import { open } from 'node:fs/promises';

const handle = await open('/run/my-app/control', 'r+');
const bridge = new RustBridge<TMyCommands>({
  binaryName: 'my-rust-server',
  inheritedFileDescriptors: [handle.fd], // available to the child as fd 3
});

await bridge.spawn();
await bridge.terminate();
await handle.close();
```

Each numeric source descriptor must remain open and refer to the intended
resource until `spawn()` resolves. Reusing the bridge with another `spawn()`
requires the descriptors to remain valid through that call as well. Closing a
source descriptor after a successful spawn does not close the child's copy, but
Smartrust never assumes ownership or closes the source itself.
Entries must be non-negative safe integers; invalid values throw `RangeError`
during bridge construction.

`inheritedFileDescriptors` applies only to `spawn()`. Calling `connect()` with a
non-empty descriptor list rejects because a socket daemon is not a child of the
bridge and cannot inherit them. Node.js does not support passing socket
descriptors this way on Windows.

### One-shot sensitive byte requests

Stdio mode can append one Smartrust-owned pipe after all caller-owned inherited
descriptors. It carries one raw byte payload without putting those bytes in the
JSON request, a string, an environment variable, or a backing file:

```typescript
const bridge = new RustBridge<TMyCommands>({
  binaryName: 'my-rust-server',
  sensitiveByteChannel: { maxPayloadSize: 2 * 1024 * 1024 },
});

await bridge.spawn();
const bytes = new Uint8Array([1, 2, 3]);
const result = await bridge.sendCommandWithSensitiveBytes('start', { port: 8080 }, bytes);
// Smartrust has cleared the exact `bytes` view before the promise settles.
```

Only one sensitive request may use a spawned generation. It runs exclusively
with respect to other commands, but ordinary JSON commands can continue after
its successful acknowledgement. A new `spawn()` creates a new pipe. Socket
mode rejects `sensitiveByteChannel` because the daemon is not a child process.

The JSON request adds only this value-free metadata:

```json
{"sensitive":{"protocol":"smartrust-sensitive-v1","fileDescriptor":3,"byteLength":3}}
```

The child descriptor is `3 + inheritedFileDescriptors.length`, so existing
inherited descriptor numbers never move. The binary frame is:

| Offset | Size | Value |
|---:|---:|---|
| 0 | 4 | ASCII `SMRS` |
| 4 | 1 | version `1` |
| 5 | 1 | flags `0` |
| 6 | 2 | big-endian request-id byte length |
| 8 | 8 | big-endian payload byte length |
| 16 | variable | ASCII request id, then raw payload bytes |

The receiver must consume and validate the complete frame before sending its
normal JSON response. That response must include an exact value-free ACK:

```json
{"sensitiveAck":{"protocol":"smartrust-sensitive-v1","consumed":true,"byteLength":3}}
```

Smartrust settles only after both the local pipe write callback and the matching
ACK, regardless of their event order. Abort, timeout, partial pipe failure,
malformed ACK, or a receiver error terminates the child and rejects every pending
request, so buffered bytes cannot become a later request.

Calling the method transfers exclusive use of the supplied mutable
`Uint8Array<ArrayBuffer>` view until settlement. Smartrust clears that exact
view after the write callback or failure. It cannot promise erasure of aliases,
JavaScript engine or Node.js internal copies, kernel pipe buffers, or memory the
receiver owns; each receiver must bound and clear its own buffers.

### Per-Command Deadlines and Cancellation

Non-streaming commands accept an optional `IRustBridgeRequestOptions` argument:

```typescript
import { RustBridgeRequestError } from '@push.rocks/smartrust';

const controller = new AbortController();

try {
  const metrics = await bridge.sendCommand(
    'getMetrics',
    {},
    {
      timeoutMs: 2000,
      signal: controller.signal,
    },
  );
} catch (error) {
  if (error instanceof RustBridgeRequestError) {
    console.error(error.code, error.message);
  }
}
```

`timeoutMs` must be a positive safe integer. When it is omitted, the bridge's
constructor-level `requestTimeoutMs` remains the default. An already-aborted
signal rejects before a request ID is allocated or anything is written.

Timeout and abort only abandon the local TypeScript wait. They do not kill or
disconnect the shared bridge, late responses are ignored, and later commands
can continue using the same bridge.

Use `maxPendingRequestsByMethod` to fail fast before serialization and transport
writes when one command type reaches its local pending-request limit. Limits are
independent, so saturated data-plane commands do not block control or callback
commands:

```typescript
const bridge = new RustBridge<TMyCommands>({
  binaryName: 'my-rust-server',
  maxPendingRequestsByMethod: {
    processData: 256,
  },
});
```

Capacity is released when the local request resolves, rejects, times out, or is
aborted, when its transport write fails, or when the bridge terminates. Regular
and streaming calls to the same method share its capacity. Every configured
limit must be a positive safe integer; invalid values throw `RangeError` during
construction. As with cancellation generally, timeout or abort cannot stop work
that was already written to Rust, so the limit bounds local pending state rather
than remote execution after local abandonment.

> The JSON-lines protocol has no cancellation message. After a command has
> been written, Rust may still execute it even if the local wait times out or
> is aborted. Do not blindly retry mutating commands; first establish whether
> the original command executed or design the command to be idempotent.

Timeout, cancellation, transport-write/exit, and Rust response failures use
`RustBridgeRequestError`.
Existing message text remains available, while `code` is stable for
programmatic handling:

| Code | Meaning |
|---|---|
| `ERR_RUST_BRIDGE_REQUEST_TIMEOUT` | The local request deadline elapsed |
| `ERR_RUST_BRIDGE_REQUEST_ABORTED` | The caller's signal aborted the local wait |
| `ERR_RUST_BRIDGE_REQUEST_LIMIT` | The configured pending-request limit for this method is full |
| `ERR_RUST_BRIDGE_REQUEST_WRITE` | The transport rejected the request write |
| `ERR_RUST_BRIDGE_REQUEST_TRANSPORT` | The transport exited, disconnected, or was killed |
| `ERR_RUST_BRIDGE_REQUEST_RUST_RESPONSE` | Rust returned `success: false` |

When Rust supplies the optional response `errorCode`, the resulting
`RustBridgeRequestError.responseErrorCode` exposes it without parsing the
message. The bridge-owned `code` remains
`ERR_RUST_BRIDGE_REQUEST_RUST_RESPONSE`, so callers can distinguish transport
failures from application-specific Rust failures. Legacy responses and
non-string `errorCode` values leave `responseErrorCode` undefined.

### Confirmed Termination

Use `await bridge.terminate()` when later work must not overlap the current
worker. In stdio mode it sends SIGTERM, escalates to SIGKILL after five seconds,
and resolves only after the child process and its stdio handles have closed.
The grace period can be changed per termination; zero requests immediate
SIGKILL:

```typescript
await bridge.terminate({ gracePeriodMs: 250 });
```

For workers that need longer cleanup, set `terminationGracePeriodMs` when
constructing the bridge. This default also applies when startup fails or stdin
breaks and cleanup begins automatically. Calling `terminate()` afterwards
cannot replace a grace period already selected by automatic cleanup.

```typescript
const bridge = new RustBridge({
  binaryName: 'worker',
  terminationGracePeriodMs: 60_000,
});
await bridge.spawn();
await bridge.terminate(); // allows up to 60 seconds before SIGKILL
```

`terminationGracePeriodMs` accepts non-negative safe integers and defaults to
5000. `StdioTransport` accepts the same constructor option. Confirmed process
closure alone does not prove that an application's external cleanup succeeded.

Concurrent calls share one termination operation, and calls after confirmed
closure are no-ops. The first concurrent caller's grace period applies. In
socket mode, termination confirms only the local socket closure; the remote
daemon is never signaled. `kill()` remains available for compatibility as a
fire-and-forget wrapper, but callers that require confirmed ownership release
must await `terminate()`.

If termination rejects, the bridge retains the transport and remains in its
stopping state because closure was not confirmed. A later `terminate()` call
starts a fresh cleanup attempt; activation remains unavailable until one of
those attempts confirms closure.

### Socket Mode — Connect to a Running Daemon 🔗

When the Rust binary runs as a system service (e.g., via `systemd`, `launchd`, or a Windows Service), use `connect()` to talk to it over a Unix socket or named pipe:

```typescript
const bridge = new RustBridge<TMyCommands>({
  binaryName: 'my-daemon',  // used for logging / error messages
});

// Connect to the daemon's management socket
const ok = await bridge.connect('/var/run/my-daemon.sock');
if (!ok) {
  console.error('Failed to connect to daemon');
  process.exit(1);
}

// Same API as stdio mode — completely transparent!
const { pid } = await bridge.sendCommand('start', { port: 8080, host: '0.0.0.0' });
const metrics = await bridge.sendCommand('getMetrics', {});

// terminate() confirms local socket closure — it does NOT kill the daemon
await bridge.terminate();
```

#### Auto-Reconnect

For long-running applications, enable automatic reconnection with exponential backoff:

```typescript
const ok = await bridge.connect('/var/run/my-daemon.sock', {
  autoReconnect: true,          // reconnect on unexpected disconnect
  reconnectBaseDelayMs: 100,    // initial retry delay (doubles each attempt)
  reconnectMaxDelayMs: 30000,   // max retry delay cap
  maxReconnectAttempts: 10,     // give up after 10 attempts
});

// Listen for reconnection events
bridge.on('reconnected', () => {
  console.log('Reconnected to daemon!');
});
```

#### Platform Notes

| Platform | Socket Path Format | Example |
|----------|-------------------|---------|
| **Linux** | `/var/run/<name>.sock` or `$XDG_RUNTIME_DIR/<name>.sock` | `/var/run/my-daemon.sock` |
| **macOS** | `/var/run/<name>.sock` | `/var/run/my-daemon.sock` |
| **Windows** | `\\.\pipe\<name>` | `\\.\pipe\my-daemon` |

Node.js `net.connect()` handles all formats transparently — no platform-specific code needed.

### Streaming Commands 🌊

For commands where the Rust binary sends a series of chunks before a final result, use `sendCommandStreaming`. This is perfect for progressive data processing, log tailing, search results, or any scenario where you want incremental output.

#### Defining Streaming Commands

Add a `chunk` field to your command type definition to mark it as streamable:

```typescript
type TMyCommands = {
  // Regular command (request → response)
  ping:        { params: {}; result: { pong: boolean } };

  // Streaming command (request → chunks... → final result)
  processData: { params: { count: number }; chunk: { index: number; progress: number }; result: { totalProcessed: number } };
  tailLogs:    { params: { lines: number }; chunk: string; result: { linesRead: number } };
};
```

#### Consuming Streams

```typescript
// Returns a StreamingResponse immediately (does NOT block)
const stream = bridge.sendCommandStreaming('processData', { count: 1000 });

// Consume chunks with for-await-of
for await (const chunk of stream) {
  console.log(`Processing item ${chunk.index}, progress: ${chunk.progress}%`);
}

// Get the final result after all chunks are consumed
const result = await stream.result;
console.log(`Done! Processed ${result.totalProcessed} items`);
```

#### Error Handling in Streams

Errors propagate to both the iterator and the `.result` promise:

```typescript
const stream = bridge.sendCommandStreaming('processData', { count: 100 });

try {
  for await (const chunk of stream) {
    console.log(chunk);
  }
} catch (err) {
  console.error('Stream failed:', err.message);
}

// .result also rejects on error
try {
  await stream.result;
} catch (err) {
  console.error('Same error here:', err.message);
}
```

A final `success: false` response rejects both paths with the same
`RustBridgeRequestError`. When the response includes an `errorCode`, its value
is available as `responseErrorCode` on that error.

#### Stream Timeout

By default, streaming commands use the same timeout as regular commands (`requestTimeoutMs`). The timeout **resets on each chunk received**, so it acts as an inactivity timeout rather than an absolute timeout. You can configure it separately:

```typescript
const bridge = new RustBridge<TMyCommands>({
  binaryName: 'my-server',
  requestTimeoutMs: 30000,   // regular command timeout: 30s
  streamTimeoutMs: 60000,    // streaming inactivity timeout: 60s
});
```

#### Implementing Streaming on the Rust Side

Your Rust binary sends stream chunks by writing lines with `"stream": true` before the final response:

```rust
// For each chunk:
println!(r#"{{"id":"{}","stream":true,"data":{{"index":{},"progress":{}}}}}"#, req.id, i, pct);
io::stdout().flush().unwrap();

// When done, send the final response (same as non-streaming):
println!(r#"{{"id":"{}","success":true,"result":{{"totalProcessed":{}}}}}"#, req.id, total);
io::stdout().flush().unwrap();
```

### Binary Locator 🔍

The `RustBinaryLocator` searches for your binary using a priority-ordered strategy:

| Priority | Source | Description |
|----------|--------|-------------|
| 1 | `binaryPath` option | Explicit path — skips all other search |
| 2 | Environment variable | e.g. `MY_SERVER_BINARY=/usr/local/bin/server` |
| 3 | Platform npm package | e.g. `@myorg/my-server-linux-x64/my-rust-server` |
| 4 | Local dev paths | `./rust/target/release/<name>` and `./rust/target/debug/<name>` |
| 5 | System PATH | Standard `$PATH` lookup |

Supplying `binaryPath` selects only that filesystem path. Relative paths resolve
against the working directory at construction, and a bare name such as `node`
does not search PATH; use `process.execPath` to select the running Node executable.
The locator snapshots its options and checks the selected target on every lookup,
including restarts. Missing paths, empty/invalid values, directories and files
without execute permission reject with `RustBinaryLocatorError` and code
`ERR_RUST_BINARY_EXPLICIT_PATH_INVALID`. Explicit selection never changes file
permissions or falls back to environment variables, packages, local builds or
PATH. These guarantees also apply to `RustBridge.spawn()`; confirmed termination
remains available after selection fails. No global environment is modified.

When `binaryPath` is omitted, the normal discovery strategy remains available.
Discovered paths are cached and revalidated before reuse; a missing cached target
triggers discovery again. Permission repair applies only to regular discovery
candidates and preserves their existing read/write permission bits.

You can also use the locator standalone:

```typescript
import { RustBinaryLocator } from '@push.rocks/smartrust';

const locator = new RustBinaryLocator({
  binaryName: 'my-rust-server',
  envVarName: 'MY_SERVER_BINARY',
  localPaths: ['/opt/myapp/bin/server'],  // custom search paths
});

const binaryPath = await locator.findBinary();
// Discovery results are cached and revalidated; clearCache() forces re-search.
```

### Configuration Reference ⚙️

The `RustBridge` constructor accepts an `IRustBridgeOptions` object:

```typescript
const bridge = new RustBridge<TMyCommands>({
  // --- Binary Locator Options ---
  binaryName: 'my-server',                    // required: name of the binary
  binaryPath: '/explicit/path/to/binary',     // optional: skip search entirely
  envVarName: 'MY_SERVER_BINARY',             // optional: env var for path override
  platformPackagePrefix: '@myorg/my-server',  // optional: platform npm package prefix
  localPaths: ['./build/server'],             // optional: custom local search paths
  searchSystemPath: true,                     // optional: search $PATH (default: true)

  // --- Bridge Options ---
  cliArgs: ['--management'],                  // optional: args passed to binary (default: ['--management'])
  inheritedFileDescriptors: [sourceFd],       // optional: caller-owned source fds mapped to child fd 3+
  sensitiveByteChannel: { maxPayloadSize: 2 * 1024 * 1024 }, // optional: one owned raw-byte pipe per spawn
  requestTimeoutMs: 30000,                    // optional: default request timeout (default: 30000)
  streamTimeoutMs: 30000,                     // optional: streaming inactivity timeout (default: requestTimeoutMs)
  readyTimeoutMs: 10000,                      // optional: ready event timeout (default: 10000)
  maxPayloadSize: 50 * 1024 * 1024,           // optional: max message size in bytes (default: 50MB)
  maxPendingRequestsByMethod: { processData: 256 }, // optional: fail-fast local request limits
  env: { RUST_LOG: 'debug' },                 // optional: extra env vars for the child process
  readyEventName: 'ready',                    // optional: name of the ready event (default: 'ready')
  logger: myLogger,                           // optional: logger implementing IRustBridgeLogger
});
```

Socket connection options (passed to `bridge.connect()`):

```typescript
interface ISocketConnectOptions {
  autoReconnect?: boolean;         // default: false
  reconnectBaseDelayMs?: number;   // default: 100
  reconnectMaxDelayMs?: number;    // default: 30000
  maxReconnectAttempts?: number;   // default: 10
}
```

### Events 📡

`RustBridge` extends `EventEmitter` and emits the following events:

| Event | Payload | Description |
|-------|---------|-------------|
| `ready` | — | Bridge connected and binary reported ready |
| `disconnected` | `IRustBridgeDisconnectedEvent` | Current transport closed, including intentional closure and the automatic reconnect gap |
| `exit` | `(code, signal)` | Unexpected transport closure with no reconnect pending, or exhausted reconnect attempts |
| `stderr` | `string` | A line from the binary's stderr (stdio mode only) |
| `reconnected` | — | Socket transport reconnected after unexpected disconnect |
| `management:<name>` | `any` | Custom event from Rust (e.g. `management:configChanged`) |

Use `disconnected` to invalidate capabilities tied to an uninterrupted IPC
connection, including when there is no pending request. Before emitting it the
bridge marks itself unavailable and rejects pending calls. The payload contains
`intentional`, `reconnecting`, `code` and `signal`; socket closures have null code
and signal. During automatic reconnect it precedes `reconnected` and the next
`ready`. A listener can call `terminate()` to stop further reconnection.
Stale transports from a replaced lifecycle cannot emit this event. It does not
prove that a separately supervised daemon stopped or replace awaited
`terminate()` for confirmed teardown.

### Custom Logger 📝

Plug in your own logger by implementing the `IRustBridgeLogger` interface:

```typescript
import type { IRustBridgeLogger } from '@push.rocks/smartrust';

const logger: IRustBridgeLogger = {
  log(level: string, message: string, data?: Record<string, any>) {
    console.log(`[${level}] ${message}`, data || '');
  },
};

const bridge = new RustBridge<TMyCommands>({
  binaryName: 'my-server',
  logger,
});
```

### Writing the Rust Side 🦀

Your Rust binary needs to implement a simple protocol. The transport (stdio or socket) doesn't change the message format — only how connections are established.

#### Stdio Mode (Child Process)

1. **On startup**, write a ready event to stdout:
   ```
   {"event":"ready","data":{"version":"1.0.0"}}\n
   ```

2. **Read JSON lines from stdin**, parse each as `{"id": "...", "method": "...", "params": {...}}`

3. **Write JSON responses to stdout**, each as `{"id": "...", "success": true, "result": {...}}\n`

4. **For streaming commands**, write zero or more `{"id": "...", "stream": true, "data": {...}}\n` chunks before the final response

5. **Emit events** anytime by writing `{"event": "name", "data": {...}}\n` to stdout

6. **Use stderr** for logging — it won't interfere with the IPC protocol

#### Socket Mode (Daemon)

1. **Listen** on a Unix socket (e.g., `/var/run/my-daemon.sock`) or Windows named pipe
2. **On each new client connection**, send the `{"event":"ready","data":{...}}\n` event
3. Read/write JSON lines on the socket (same protocol as stdio)
4. Support multiple concurrent clients — each connection is independent

Here's a minimal Rust skeleton (stdio mode):

```rust
use serde::{Deserialize, Serialize};
use std::io::{self, BufRead, Write};

#[derive(Deserialize)]
struct Request {
    id: String,
    method: String,
    params: serde_json::Value,
}

#[derive(Serialize)]
struct Response {
    id: String,
    success: bool,
    #[serde(skip_serializing_if = "Option::is_none")]
    result: Option<serde_json::Value>,
    #[serde(skip_serializing_if = "Option::is_none")]
    error: Option<String>,
}

#[derive(Serialize)]
struct StreamChunk {
    id: String,
    stream: bool,
    data: serde_json::Value,
}

fn main() {
    // Signal ready
    println!(r#"{{"event":"ready","data":{{"version":"1.0.0"}}}}"#);
    io::stdout().flush().unwrap();

    let stdin = io::stdin();
    for line in stdin.lock().lines() {
        let line = line.unwrap();
        let req: Request = serde_json::from_str(&line).unwrap();

        match req.method.as_str() {
            "ping" => {
                let resp = Response {
                    id: req.id,
                    success: true,
                    result: Some(serde_json::json!({"pong": true})),
                    error: None,
                };
                println!("{}", serde_json::to_string(&resp).unwrap());
                io::stdout().flush().unwrap();
            }
            "processData" => {
                let count = req.params["count"].as_u64().unwrap_or(0);
                // Send stream chunks
                for i in 0..count {
                    let chunk = StreamChunk {
                        id: req.id.clone(),
                        stream: true,
                        data: serde_json::json!({"index": i, "progress": ((i+1) * 100 / count)}),
                    };
                    println!("{}", serde_json::to_string(&chunk).unwrap());
                    io::stdout().flush().unwrap();
                }
                // Send final response
                let resp = Response {
                    id: req.id,
                    success: true,
                    result: Some(serde_json::json!({"totalProcessed": count})),
                    error: None,
                };
                println!("{}", serde_json::to_string(&resp).unwrap());
                io::stdout().flush().unwrap();
            }
            _ => {
                let resp = Response {
                    id: req.id,
                    success: false,
                    result: None,
                    error: Some(format!("Unknown method: {}", req.method)),
                };
                println!("{}", serde_json::to_string(&resp).unwrap());
                io::stdout().flush().unwrap();
            }
        }
    }
}
```

## Architecture 🏗️

```
┌──────────────────────────────────────────────────────┐
│                    RustBridge<T>                      │
│  (protocol layer: handleLine, sendCommand, events)   │
├──────────────┬───────────────────────────────────────┤
│ StdioTransport │         SocketTransport             │
│  spawn() +     │   net.connect() + auto-reconnect    │
│  stdin/stdout  │   Unix socket / named pipe          │
├──────────────┴───────────────────────────────────────┤
│               IRustTransport interface               │
│         connect() / write() / disconnect()           │
├──────────────────────────────────────────────────────┤
│       LineScanner (shared newline scanner)            │
├──────────────────────────────────────────────────────┤
│              RustBinaryLocator                        │
│  (binary search — stdio mode only)                   │
└──────────────────────────────────────────────────────┘
```

- **`RustBridge`** — The main class. Protocol-level logic (JSON parsing, request correlation, streaming, events) is transport-agnostic.
- **`StdioTransport`** — Spawns a child process, manages stdin/stdout/stderr, handles SIGTERM/SIGKILL.
- **`SocketTransport`** — Connects to an existing Unix socket or named pipe, with optional auto-reconnect and exponential backoff.
- **`LineScanner`** — Shared buffer-based newline scanner used by both transports for efficient message framing.
- **`RustBinaryLocator`** — Priority-ordered binary search (used by stdio mode only).

## API Reference 📖

### `RustBridge<TCommands>`

| Method / Property | Signature | Description |
|---|---|---|
| `constructor` | `new RustBridge<T>(options: IRustBridgeOptions)` | Create a new bridge instance |
| `spawn()` | `Promise<boolean>` | **Stdio mode**: Spawn and wait for ready; rejects invalid explicit selection, returns `false` for ordinary discovery/startup failure |
| `connect(socketPath, options?)` | `Promise<boolean>` | **Socket mode**: Connect to a running daemon; returns `false` on connection/readiness failure and rejects stdio-only descriptor/byte-channel options |
| `sendCommand(method, params, options?)` | `Promise<TCommands[K]['result']>` | Send a typed command with an optional per-call timeout or abort signal |
| `sendCommandWithSensitiveBytes(method, params, bytes, options?)` | `Promise<TCommands[K]['result']>` | Send one exclusive JSON command with its raw bytes on the generation-owned one-shot pipe |
| `sendCommandStreaming(method, params)` | `StreamingResponse<TChunk, TResult>` | Send a streaming command; returns immediately |
| `terminate(options?)` | `Promise<void>` | Confirm stdio child exit or local socket closure; `gracePeriodMs` controls SIGKILL escalation |
| `kill()` | `void` | Fire-and-forget compatibility wrapper around `terminate()` |
| `running` | `boolean` | Whether the bridge is currently connected and ready |

### `StreamingResponse<TChunk, TResult>`

| Method / Property | Type | Description |
|---|---|---|
| `[Symbol.asyncIterator]()` | `AsyncIterator<TChunk>` | Enables `for await...of` consumption of chunks |
| `result` | `Promise<TResult>` | Resolves with the final result after stream ends |

### `RustBinaryLocator`

| Method / Property | Signature | Description |
|---|---|---|
| `constructor` | `new RustBinaryLocator(options: IBinaryLocatorOptions, logger?)` | Create a locator instance |
| `findBinary()` | `Promise<string \| null>` | Validate explicit selection or discover a binary; rejects invalid explicit selection; revalidates cached discovery results |
| `clearCache()` | `void` | Clear the cached path to force a fresh search |

### `StdioTransport`

| Method / Property | Signature | Description |
|---|---|---|
| `constructor` | `new StdioTransport(options: IStdioTransportOptions)` | Create a stdio transport |
| `connect()` | `Promise<void>` | Spawn the child process |
| `write(data)` | `Promise<void>` | Write to stdin with backpressure handling |
| `disconnect()` | `void` | Kill the process (SIGTERM → SIGKILL after 5s) |
| `disconnectAndWait(options?)` | `Promise<void>` | Confirm child close after SIGTERM/SIGKILL escalation |
| `connected` | `boolean` | Whether the process is running |

### `SocketTransport`

| Method / Property | Signature | Description |
|---|---|---|
| `constructor` | `new SocketTransport(options: ISocketTransportOptions)` | Create a socket transport |
| `connect()` | `Promise<void>` | Connect to the Unix socket / named pipe |
| `write(data)` | `Promise<void>` | Write to socket with backpressure handling |
| `disconnect()` | `void` | Close the socket (does not kill the daemon) |
| `disconnectAndWait()` | `Promise<void>` | Confirm local socket closure without signaling the daemon |
| `connected` | `boolean` | Whether the socket is connected |
| `reconnecting` | `boolean` | Whether an automatic reconnect timer or attempt owns the socket lifecycle |

### `LineScanner`

| Method / Property | Signature | Description |
|---|---|---|
| `constructor` | `new LineScanner(maxPayloadSize, logger)` | Create a line scanner |
| `push(chunk, onLine)` | `void` | Feed a `Buffer` chunk; calls `onLine` for each complete line |
| `clear()` | `void` | Reset the internal buffer |

### Exported Interfaces & Types

| Interface / Type | Description |
|---|---|
| `IRustBridgeOptions` | Full configuration for `RustBridge` |
| `IRustBridgeRequestOptions` | Per-command options: `{ signal?, timeoutMs? }` |
| `IRustBridgeTerminateOptions` | Confirmed termination options: `{ gracePeriodMs? }` |
| `IRustTransportDisconnectOptions` | Optional confirmed-disconnect grace period for owned process transports |
| `IBinaryLocatorOptions` | Configuration for `RustBinaryLocator` |
| `ISocketConnectOptions` | Socket connection options (reconnect settings) |
| `IRustBridgeLogger` | Logger interface: `{ log(level, message, data?) }` |
| `IRustTransport` | Transport interface (extends `EventEmitter`) |
| `IManagementRequest` | IPC request shape: `{ id, method, params }` |
| `IManagementResponse` | IPC response shape: `{ id, success, result?, error?, errorCode? }` |
| `IManagementEvent` | IPC event shape: `{ event, data }` |
| `IManagementStreamChunk` | IPC stream chunk shape: `{ id, stream: true, data }` |
| `ICommandDefinition` | Single command definition: `{ params, result }` |
| `TCommandMap` | `Record<string, ICommandDefinition>` |
| `TStreamingCommandKeys<T>` | Extracts keys from a command map that have a `chunk` field |
| `TExtractChunk<T>` | Extracts the chunk type from a streaming command definition |
| `RustBridgeRequestError` | Request error class with stable `code`, optional `responseErrorCode`, `requestId`, and `method` fields |
| `TRustBridgeRequestErrorCode` | Union of stable request error code strings |

## License and Legal Information

This repository contains open-source code licensed under the MIT License. A copy of the license can be found in the [license](./license) file.

**Please note:** The MIT License does not grant permission to use the trade names, trademarks, service marks, or product names of the project, except as required for reasonable and customary use in describing the origin of the work and reproducing the content of the NOTICE file.

### Trademarks

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Use of these trademarks must comply with Task Venture Capital GmbH's Trademark Guidelines or the guidelines of the respective third-party owners, and any usage must be approved in writing. Third-party trademarks used herein are the property of their respective owners and used only in a descriptive manner, e.g. for an implementation of an API or similar.

### Company Information

Task Venture Capital GmbH
Registered at District Court Bremen HRB 35230 HB, Germany

For any legal inquiries or further information, please contact us via email at hello@task.vc.

By using this repository, you acknowledge that you have read this section, agree to comply with its terms, and understand that the licensing of the code does not imply endorsement by Task Venture Capital GmbH of any derivative works.

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