35c5adc6f3
drain_trace now joins its four recording-sink taps through aura-engine's join_on_ts instead of a hand-rolled per-tap HashMap, resolving the #93 zip-by-index panic at its source: the four taps fire at different cardinalities (breakout one bar short via cold Delay(1); bars_since_open filtered by Session), so a positional zip misaligns or panics. The BarTrace mapping stays a thin layer with its caller-side defaults unchanged (held->0.0, bars_since_open->-1, breakout->false) — the engine reports presence, the consumer interprets absence. Behaviour is byte-preserved: the gated GER40 tests (ger40_breakout_real, ger40_breakout_blueprint, open_ohlc_seam) stay green against the real archive. The Recorder doc gains a prose note on the multi-tap cadence rule (join on ts, never by index), pointing at join_on_ts by name rather than rustdoc link since aura-std does not depend on aura-engine. Verified: cargo build/test/clippy --workspace --all-targets clean; the _by_ts hand-rolled join is gone (acceptance grep empty). closes #93