Workspace member 8 of 8. Library + binary; mirrored slice-2's
rutster-tap-echo shape. Three stub modules (api_key, translator,
openai_client) filled in by Tasks 3-5. No behavioral code yet —
this task only locks the crate boundary + the new async-trait dep
(the Tool trait in Task 6 needs it for async-fns-in-trait-objects).
The RtcSession module doc cited the dropped rutster-signaling-sip crate
and a 'future SIP SDP path' that ADR-0007 superseded. Re-anchor on
ADR-0007: no first-party SIP/SDP — the trunk is rented (CPaaS media-leg)
or out-of-tree SBC, so rutster's SDP is WebRTC-only via str0m. Final
straggler of the rutster-signaling-sip → rutster-trunk rename.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KhhqKG4cra7d1PBoVbj9UJ
ADR-0007 lands in code:
- Rename crates/rutster-signaling-sip → crates/rutster-trunk. The crate was
a stub anyway (lib.rs with a doc-comment + crate_compiles() test); the
rename locks the new boundary shape — the future rented-transport
ingress (CPaaS media-leg fork / out-of-tree SBC glue, **no SIP stack**)
lands here at spearhead step 5.
- rutster-trunk/src/lib.rs doc-comment now describes the ADR-0007 split:
CPaaS media-leg adapter as primary, out-of-tree SBC for on-prem
graduation. Cross-refs ADR-0007 + ADR-0008 (FOB vs. green zone: trunk
is green zone; SIP lives outside the trust boundary).
- rutster-spend/src/lib.rs doc-comment updated to quote ADR-0007's
'rutster mediates both the provider call-control API and the brain tap'
framing — the spend gate sits in that boundary, structurally preventing
a runaway brain from exceeding spend/pacing. Pulling spend out into a
service re-introduces the 3-vendor structural hole.
Cargo bumps:
- edition = '2024' (slice-1's pinned Rust 1.85 + edition-2024 floor
already requires this; rutster-media's let-else pattern in
OpusDecoder::decode · Slice-2's let-else in AcceptOffer's Uuid
parse_str · all rely on edition 2024's stabilized let-chains / let-else).
- repository = 'https://git.adlee.work/alee/rutster' (the self-hosted
Gitea remote — matches 'git remote -v' origin). The github.com/anomalyco
URL was stale from the pre-pivot copy.
- Cargo.lock regenerated by cargo for the rename.
No behavioral code changes — the trunk crate's body is still the stub
crate_compiles() test. FOB membership (per ADR-0008) is unchanged:
rutster-trunk will be FOB-internal at step 5 because it's the media-leg
ingress (hot path); spend-spend stays FOB because spend is
security-constitutive.
- session_map.rs: AppState::close outer timeout bumped 500ms → 750ms
so the inner close-arm bound (500ms in tap_client.rs) has room to
finish `ws.close(None).await` cleanly before the abort fallback
fires. Outer > inner per final-fixes re-review Important #1.
- tap_integration.rs: reconnect-path test now asserts the resumed
`next_pcm_frame()` returns the FRESH marker (samples[0] == 9, not
the stale samples[0] == 7), actively witnessing the §5.3 step 4
"no stale bleed-through" contract. Pre-kill seeding strengthened
to ≥2 frames so step 7's silence-after-flush assertion is non-
vacuous. Per final-fixes re-review Important #2.
Spec ref: 2026-06-28-slice-2-agent-tap-design.md §5.1 step 5, §5.3 step 4.
Code-review findings from the slice-2 final whole-branch review:
- tap_client.rs: close arm sends session_end (not bye) per §5.2, awaits
brain bye with bounded 500ms timeout, then ws.close(). Promotes the
Task-7-documented Minor to Important's required spec compliance.
- session_map.rs: AppState::close() now clears channel.tap = None before
Closing->Closed, sends close signal, bounded-awaits engine task for the
teardown handshake (500ms cap), aborts as fallback. Per §5.1 step 5.
- pcm.rs + tap_audio_pipe.rs: AudioPipe trait gains clear_playout_ring()
(default no-op for EchoAudioPipe); TapAudioPipe clears the VecDeque.
RtcSession::clear_playout_ring delegates. Per §5.3 step 4 playout-on-
disconnect-flush contract.
- tap_engine.rs: spawn_tap_engine creates + shares a flush_tx mpsc
channel; run_engine_loop signals flush after each failed pump loop
(before backoff); TapConn.flush_rx is drained by drive_all_sessions
to call RtcSession::clear_playout_ring.
- tests/tap_integration.rs: new reconnect-path test asserts Channel
stays Connected, metrics.reconnect_attempts increments, playout
returns None during outage, playout resumes after EchoServer
restart with fresh frames (no stale bleed-through). Per §8.4.
- static/index.html: one static line acknowledging external-brain
routing per §7.2 (defer real-time tap status to step-3 GUI).
Spec ref: 2026-06-28-slice-2-agent-tap-design.md §5.1 step 5, §5.2, §5.3 step 4, §7.2, §8.4.
- tap_engine.rs: Backoff::next_delay now matches spec §4.3 exactly:
250ms -> 500ms -> 1s -> 2s -> 5s cap (no intermediate 4s step from
naive doubling). Test asserts the spec enumeration including the
"stays at 5s forever" cap-after-step-5 invariant.
- session_map.rs: removed the dead 'Closing && tap.is_some()' branch
from drive_all_sessions. AppState::close already handles teardown
inline (fires close_tx, aborts task, clears field, advances
state, removes entry). The branch was never exercised and
pre-paved a "future peer-initiated close" path -- both AGENTS.md
anti-patterns ("don't pre-pave the wrong pattern").
Spec ref: 2026-06-28-slice-2-agent-tap-design.md §4.3 step 4 + §5.1 step 3.
- pub struct TapHandle(()) — zero-sized marker (Option<TapHandle> compiles
to a bool, no allocation). The live tap connection lives in the binary's
DashMap<ChannelId, TapConn>, keyed by the channel's existing ChannelId
(== wire session_id per spec §5.3).
- Channel grows pub tap: Option<TapHandle>. None until Connected, set on
Connected, cleared before state advances to Closed.
- State invariant: tap and ChannelState are tied (Connected+None=bug).
- Slice-1 backwards compatible: new field is Option<...>;
Multi-tap-per-channel is the future trigger for a TapId newtype (YAGNI).
Spec ref: 2026-06-28-slice-2-agent-tap-design.md §5.2, §6.
- 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.
