---
id: ws-upgrade-session
name: WS upgrade route + channels session (server producer half)
status: completed
depends_on: [ws-byte-adapter, server-adapter]
scope: broad
risk: high
impact: phase
level: implementation
tags: [websocket, phase-2]
---

## Description

Implement the WS upgrade handler per ADR-067/websocket.md, production
shape: axum route at `/alk/channels`; bearer auth on the upgrade
request (401 without token); upgrade → adapt the WS stream with the
byte-adapter (ws-byte-adapter) → `Connection::from_bidi(ws_stream,
b"alk/channels")` → run the channels accept path: alkcall
`ChannelsAdapter` in-line demux with the `install_channel_zero` hook
constructing channel 0's `CallConnection` (identity attached) and
running `Dispatcher::run_loop_single_stream`. Text messages rejected
(WS close 1002). Overlay-only session construction mirrors the alknet
`upgrade.rs::run_ws_session` shape but through the channels machinery.

## Acceptance Criteria

- [x] Upgrade route wired into HttpAdapter's router (reserved-path collision rule respected)
- [x] End-to-end test: WS client (tokio-tungstenite or axum test client) → upgrade → chunk-framed call.requested on channel 0 → response received
- [x] Browser-style test: services/list via channel 0, AccessControl-filtered
- [x] Disconnect mid-call: pending requests failed, overlay dropped, no hang
- [x] 16 MiB chunk split/reassembly test carried over from the POC
- [x] `cargo test` passes

## References

- docs/architecture/websocket.md (full spec)
- docs/architecture/decisions/067-websocket-carries-channels.md
- alkcall `channels/client.rs` tests (make_install_channel_zero wiring pattern)
- Old source: `/workspace/@alkdev/alknet/crates/alknet-http/src/websocket/upgrade.rs` (session lifecycle; framing superseded)

## Notes

> Agent fills during implementation.

## Summary

Implemented the WS upgrade route + channels session (server producer
half), production shape:

- `src/websocket/byte_adapter.rs`: WsByteStream (WS <-> AsyncRead+Write).
  Production hardening over the POC: write-side backpressure via
  futures::channel::mpsc poll_ready (replaces the POC spin-wait);
  text-message rejection via WriteMsg::CloseWith(1002) routed through
  the writer task; CloseWith(code)/queue-drain close mapping. Shared
  with from_wss (ADR-070).
- `src/websocket/upgrade.rs`: ws_upgrade_handler (Extension<Identity>,
  401 without a resolvable token via ws_bearer_auth middleware sharing
  server::auth::extract_bearer_identity), run_channels_session
  (Connection::from_bidi b"alk/channels" + set_identity ->
  ChannelsAdapter with NoCap policy), install_channel_zero hook =
  alkcall channels/client.rs accept-side pattern (split_single_stream ->
  CallConnection::new_single_stream -> Dispatcher::run_loop_single_stream).
- `src/websocket/test_support` (feature test-support): WsClient +
  chunk/frame assemblers for integration tests and downstream use.
- `tests/ws_upgrade_session.rs`: 10 tests over real TCP sockets —
  round-trip, 401 no-token, 401 unresolvable token, 3 MiB chunk split
  round-trip with byte-integrity, 20 interleaved calls correlation,
  mid-call disconnect no-hang, text->1002 close, ACL 403 FORBIDDEN,
  internal-op NOT_FOUND, services/list AccessControl-filtered.

95 lib + 10 integration tests green (default + all-features).