Files
wraith/docs/architecture/decisions/007-napi-single-stream.md
glm-5.1 dad8224686 Add architecture specification for wraith SSH tunnel tool
Docs:
- README.md: index with doc table, ADR table, lifecycle definitions
- overview.md: purpose, exports, dependencies, constraints
- transport.md: Transport trait, TCP/TLS/iroh implementations, stream join
- client.md: SOCKS5 server, port forwarding, channel manager, reconnection
- server.md: auth, channel handling, stealth mode, outbound proxy
- tun-shim.md: separate privileged process, virtual DNS, --unshare mode
- napi-and-pubsub.md: NAPI wrapper, pubsub event target adapter

ADRs:
- 001: Pluggable transport via AsyncRead+AsyncWrite trait
- 002: TUN shim as separate process
- 003: iroh stream via tokio::io::join
- 004: SSH runs over transport, not alongside
- 005: SOCKS5 as primary interface, TUN as add-on
- 006(007): NAPI exposes single duplex stream

Open questions: 11 items covering TLS certs, iroh relay defaults,
Windows TUN, auth expansion, NAPI surface, TCP reconstruction
2026-06-01 15:01:45 +00:00

26 lines
1.7 KiB
Markdown

# ADR-006: NAPI Exposes Single Duplex Stream
## Status
Accepted
## Context
The NAPI wrapper for wraith could expose different granularity levels:
1. **Full SSH API**: Expose channel multiplexing, `open_direct_tcpip`, `tcpip_forward`, session management. The TypeScript layer would manage channels.
2. **Single duplex stream**: The NAPI wrapper establishes one SSH channel and returns it as a Node.js `Duplex` stream. TypeScript multiplexing (if needed) happens at the pubsub layer.
## Decision
Option 2: NAPI exposes a single duplex stream.
The NAPI wrapper's job is to get a reliable, authenticated byte stream from A to B. It handles transport (TCP/TLS/iroh), SSH authentication, and channel setup, then hands the caller a single `Duplex` stream that just works.
If the TypeScript consumer needs multiplexing (e.g., multiple concurrent tool calls over operations), pubsub handles that at the `EventEnvelope` level. Multiple `call.requested` / `call.responded` events flow over the same stream, distinguished by their `id` fields. This is how the existing WebSocket adapter works.
## Consequences
- **Positive**: Minimal NAPI surface — one function, one return type. Small binary, small FFI boundary.
- **Positive**: The TypeScript side doesn't need to understand SSH at all. It gets a stream and sends/receives `EventEnvelope` JSON.
- **Positive**: No need to expose russh types in NAPI. The SSH complexity stays in Rust.
- **Negative**: If a consumer wants multiple isolated channels (e.g., one for events, one for file transfer), they'd need multiple `connect()` calls (multiple SSH sessions). This is acceptable for the expected use case (pubsub events over a single stream).
## References
- [napi-and-pubsub.md](../napi-and-pubsub.md)