readme.md for @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.
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Install 📦
npm install @push.rocks/smartrust
# or
pnpm install @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"}
Error correlated by ID
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:
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:
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);
});
// Clean shutdown (SIGTERM → SIGKILL after 5s)
bridge.kill();
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:
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', {});
// kill() closes the socket — it does NOT kill the daemon
bridge.kill();
Auto-Reconnect
For long-running applications, enable automatic reconnection with exponential backoff:
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:
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
// 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:
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);
}
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:
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:
// 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
You can also use the locator standalone:
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();
// Result is cached — call clearCache() to force re-search
Configuration Reference ⚙️
The 
RustBridge constructor accepts an 
IRustBridgeOptions object:
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 $PATH (default: true)
  // --- Bridge Options ---
  cliArgs: ['--management'],                  // optional: args passed to binary (default: ['--management'])
  requestTimeoutMs: 30000,                    // optional: per-request timeout (default: 30000)
  streamTimeoutMs: 30000,                     // optional: streaming inactivity timeout (default: requestTimeoutMs)
  readyTimeoutMs: 10000,                      // optional: ready event timeout (default: 10000)
  maxPayloadSize: 50 * 1024 * 1024,           // optional: max message size in bytes (default: 50MB)
  env: { RUST_LOG: 'debug' },                 // optional: extra env vars for the child process
  readyEventName: 'ready',                    // optional: name of the ready event (default: 'ready')
  logger: myLogger,                           // optional: logger implementing IRustBridgeLogger
});
Socket connection options (passed to 
bridge.connect()):
interface ISocketConnectOptions {
  autoReconnect?: boolean;         // default: false
  reconnectBaseDelayMs?: number;   // default: 100
  reconnectMaxDelayMs?: number;    // default: 30000
  maxReconnectAttempts?: number;   // default: 10
}
Events 📡
RustBridge extends 
EventEmitter and emits the following events:
Event
Payload
Description
ready
—
Bridge connected and binary reported ready
exit
(code, signal)
Transport closed (process exited or socket disconnected)
stderr
string
A line from the binary's stderr (stdio mode only)
reconnected
—
Socket transport reconnected after unexpected disconnect
management:<name>
any
Custom event from Rust (e.g. 
management:configChanged)
Custom Logger 📝
Plug in your own logger by implementing the 
IRustBridgeLogger interface:
import type { IRustBridgeLogger } from '@push.rocks/smartrust';
const logger: IRustBridgeLogger = {
  log(level: string, message: string, data?: Record<string, any>) {
    console.log(`[${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)
On startup, write a ready event to stdout:
{"event":"ready","data":{"version":"1.0.0"}}\n
Read JSON lines from stdin, parse each as 
{"id": "...", "method": "...", "params": {...}}
Write JSON responses to stdout, each as 
{"id": "...", "success": true, "result": {...}}\n
For streaming commands, write zero or more 
{"id": "...", "stream": true, "data": {...}}\n chunks before the final response
Emit events anytime by writing 
{"event": "name", "data": {...}}\n to stdout
Use stderr for logging — it won't interfere with the IPC protocol
Socket Mode (Daemon)
Listen on a Unix socket (e.g., 
/var/run/my-daemon.sock) or Windows named pipe
On each new client connection, send the 
{"event":"ready","data":{...}}\n event
Read/write JSON lines on the socket (same protocol as stdio)
Support multiple concurrent clients — each connection is independent
Here's a minimal Rust skeleton (stdio mode):
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 the binary and wait for ready; returns 
false on failure
connect(socketPath, options?)
Promise<boolean>
Socket mode: Connect to a running daemon; returns 
false on failure
sendCommand(method, params)
Promise<TCommands[K]['result']>
Send a typed command and await the response
sendCommandStreaming(method, params)
StreamingResponse<TChunk, TResult>
Send a streaming command; returns immediately
kill()
void
Stdio: SIGTERM the process, SIGKILL after 5s. Socket: close the connection (daemon stays alive)
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>
Find the binary using the priority search; result is cached
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)
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)
connected
boolean
Whether the socket is connected
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
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? }
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
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 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
This project is owned and maintained by Task Venture Capital GmbH. The names and logos associated with Task Venture Capital GmbH and any related products or services are trademarks of Task Venture Capital GmbH or third parties, and are not included within the scope of the MIT license granted herein.
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.