- run_tap_client: drives a connected WebSocketStream with a tokio::select!
over rx_pcm_in (inbound PCM → audio_in WS frame) and ws.next() (brain
frame → audio_out mpsc or control handling).
- Handshake: send hello, await brain hello (bounded 2s timeout).
- seq gap detection (log + count, never drop on gap — spec §3.1).
- Hot-path errors (encode/decode failures, send/recv failures) are logged
+ counted; TapClientError is returned only on graceful close, hello
timeout, or WS errors. The TapEngine (Task 7) decides reconnect policy.
- Pure-helper unit test (elapsed_ms); full pump behavior is exercised
against the in-process EchoServer in the Task 8 integration test.
Spec ref: 2026-06-28-slice-2-agent-tap-design.md §4.2.
- Add tokio-tungstenite 0.24, futures-util 0.3, url 2, base64 0.22 to
[workspace.dependencies] (spec §8.1).
- Add crates/rutster-tap-echo as 7th workspace member (spec §2).
- Transition crates/rutster-tap/Cargo.toml from stub to real manifest
with the deps Tasks 2-4 will need (rutster-media, tokio, tokio-tungstenite,
serde, serde_json, base64, url, thiserror, tracing).
- Skeleton lib.rs (compile test) + main.rs (placeholder fn main) for
rutster-tap-echo; Task 5 fills in the echo logic.
- Verify cargo deny check passes against the new transitive dep tree.
Spec ref: docs/superpowers/specs/2026-06-28-slice-2-agent-tap-design.md §2, §8.1.
Two Important findings from the final whole-branch review:
T4-M3: RtcSession::channel_id/channel_state/is_closed lacked /// docs
(AGENTS.md mandates /// on every public item; learner-facing code is a
primary product). One-line docs added per existing /// style in rtc_session.rs.
T7-M2: README "Status" section still read "Scoping. No code yet" — stale
post-slice-1. Updated to reflect slice-1 implementation status; minimal
edit, surrounding content preserved.
Four routes on axum 0.7 per spec §4.1: POST /v1/sessions (mint),
POST /v1/sessions/:id/offer (str0m-native SDP accept), DELETE
/v1/sessions/:id (close), GET / (static HTML client). Session store is
a DashMap<ChannelId, Arc<Mutex<RtcSession>>> (spec §4.5); one tokio
task drives all session poll loops — per-session tasks would pre-pave
the wrong pattern for step 4's dedicated thread. Graceful shutdown
drops the DashMap on Ctrl-C / SIGTERM. Integration test exercises the
REST surface; manual browser e2e per README §6.5.
RtcSession owns a str0m::Rtc + Opus decoder/encoder + EchoAudioPipe +
a bound UDP socket (spec §3.1, §4.5). accept_offer calls str0m 0.21's
sdp_api().accept_offer() natively — no hand-rolled SDP munger; str0m
fills DTLS fingerprint + ICE creds + Opus codec. The loop driver
drains poll_output per str0m's single-mutation invariant, routes
inbound MediaData through Opus decode + EchoAudioPipe sink, sends
Transmit packets on the UDP socket, and checks the 60 s idle timeout.
DEV-DEVIATION: loop runs on tokio (spec §3.4); step 4 replaces with
a dedicated timing thread per ARCHITECTURE.md.
str0m 0.21 API adjustments from the brief's sketch (verified against
src/str0m-0.21.0):
- SdpAnswer has no .mid() accessor; use answer.media_lines[0].mid()
via the Deref<Target=Sdp> impl.
- Input::Receive carries the Instant as the first tuple element
(Input::Receive(now, recv)); handle_input takes a single Input arg.
- Receive constructed via Receive::new(proto, src, dst, buf) (the
DatagramRecv field is private).
- UDP socket binds 127.0.0.1:0 (Candidate::host rejects the
unspecified address 0.0.0.0).
- BROWSER_SDP_OFFER fixture restored a=group:BUNDLE 0 (str0m's
Sdp::assert_consistency rejects SDP without a session group).
PcmFrame is the canonical tap format (16-bit mono @ 24 kHz, 480 samples
per 20 ms frame — ARCHITECTURE.md). AudioSource/AudioSink are the seam
step 2 splices the tap client into (spec §3.3); EchoAudioPipe is the
slice-1 wiring of that seam. OpusDecoder/OpusEncoder wrap the opus
crate's libopus FFI with hot-path match-and-continue (no ? on the 20 ms
loop, spec §3.8); decode/encode return Option<PcmFrame>/Option<Vec<u8>>
so a dropped frame is logged + counted, never propagated to crash the
peer.
rutster-call-model is real-but-minimal (spec §5): the unifying leg
object the future API exposes. ChannelId is a Uuid newtype for
type-safety (the slice-1 worked example of the newtype pattern).
Channel is signaling-state only — media lives in rutster-media as a
leaf concern of the Channel, surfaced only when a second consumer needs
to observe it (spec §5.3). ChannelState matches the New→Connecting→
Connected→Closing→Closed flow from §5.4.
Workspace root, pinned toolchain, and the three stub crates whose only
job in slice 1 is to lock the ADR-0002 boundary shape. Each ships a
lib.rs module doc (what it will hold, why deferred, which spearhead step
fills it) and a crate_compiles test. Spec §2.2.
