API-surface corrections (verified against str0m 0.21 docs):
- str0m::Live -> str0m::Rtc (no Live type exists)
- needs_input_timeout() -> Rtc::poll_output() returning Output::Timeout(Instant)
- RtcConfig::with_dtls_cert -> RtcConfig::set_dtls_cert (also: str0m auto-gens
a cert if none passed; slice 1 still passes explicitly for ownership clarity)
- Event::RtpPacket(pkt, rid) -> Event::RtpPacket(RtpPacket) { single struct,
RID is a field }
- str0m::ice::IceAgent -> no public 'ice' module; ICE types at crate root:
Candidate, CandidateKind, IceCreds, IceConnectionState
- str0m.write_rtp() on Rtclive -> Frame API path: Rtc::writer(mid) -> Writer::write
New design decision surfaced by API verification:
- Media API path: Frame API (default) vs RTP API (set_rtp_mode(true)).
Slice 1 uses Frame API — the proof target is the codec-to-PCM boundary,
not RTP packetization. RTP API is a candidate for step 5.
Design-level fixes from close reading:
- §3.3 AudioSource/AudioSink: clarify who drives the traits (the poll loop
drives both; sink on inbound MediaData, source on Output::Timeout deadline)
- §3.6: clarify cert/CrossRef — fresh in-memory cert each restart is safe
because browser fetches fresh SDP each session, no caching layer to go stale
- §4.1: add Content-Type: application/sdp to /offer (browser-side fetch needs
it)
- §4.5: resolve 5-min-vs-60s idle-timeout contradiction (60s, not 5 min)
- §4.5: add graceful-shutdown story (drop DashMap on SIGINT, browsers see
dead peer — acceptable for dev loop)
- §6.4: fix 'mocked str0m Rtc' — str0m's Rtc is a concrete struct, not a
trait; sans-IO means drive real Rtc with synthetic Inputs, not mock it.
Stronger than mocking: production path exercised exactly.
Resolves 5 load-bearing API errors + 3 design-level ambiguities. Spec is now
implementation-ready pending user review.
- Clarify RtcSession/Channel ownership: ChannelId IS the session id;
RtcSession owns both str0m Live + codecs and the Channel. Fixes ambiguity.
- Drop the separate /ice endpoint: non-trickle ICE bundles candidates
into the SDP offer/answer, so the endpoint was redundant. Fixes
contradiction.
- Clarify idle timeout = 'no RTP for 60s' (not 5 min blanket), and that
no per-session tokio task is spawned (pre-paves the wrong pattern
for step 4's dedicated thread).
- 'reflex to police' -> 'reflex to enforce' (terminology: avoid
authoritarian verbs).
Workspace scaffold + spearhead step 1: browser talks WebRTC to the core,
core terminates DTLS-SRTP, decodes Opus to canonical 16-bit PCM @24 kHz mono,
echoes back. Proves the media core + the codec-to-PCM boundary (pre-paves
the tap). Stubs lock the ADR-0002 fused-vertical boundaries for steps
2/5/6.
Drafted in brainstorming session 2026-06-28.
