plan(slice-2): agent tap implementation plan (spec §1.1)
8 TDD tasks, 53 checkbox steps, sequentially dependent:
1. Workspace deps + rutster-tap-echo skeleton (build foundation)
2. Tap wire protocol (spec §3) — JSON envelope, explicit LE PCM codec
3. TapMetrics + TapAudioPipe (spec §4.1) — the seam object
4. TapClient WSS pump loop (spec §4.2) — async WS pump + seq gap detection
5. Rust echo brain crate (spec §2.3) — stereotype binary + in-process EchoServer
6. Call-model TapHandle + Channel field (spec §5.2, §6)
7. Binary wiring — TapEngine + session_map + routes + main (spec §5.1, §7)
8. Integration test + Python echo brain + LEARNING.md (spec §8.4, §8.5 #7)
Plan self-reviewed: no placeholders; TapHandle::new visibility fixed
(pub(crate) → pub); spawn_tap_engine return shape fixed (returns
(TapAudioPipe, TapConn) tuple, not TapConn holding the pipe's mpsc).
Spec ref: 2026-06-28-slice-2-agent-tap-design.md (commit f83bca9).
22d3f03b8c