feat(rvcsi): real nexmon_csi UDP/PCAP fidelity — chanspec decode, libpcap reader, NexmonPcapAdapter
Raises the Nexmon path from a normalized record format to parsing what the
patched Broadcom firmware actually emits, end to end.
napi-c shim (ABI 1.0 -> 1.1, additive):
- rvcsi_nx_csi_udp_header / rvcsi_nx_csi_udp_decode — parse the real nexmon_csi
UDP payload: the 18-byte header (magic 0x1111, rssi int8, fctl, src_mac[6],
seq_cnt, core/spatial-stream, Broadcom chanspec, chip_ver) + nsub complex CSI
samples (modern int16 LE I/Q export — what CSIKit/csireader.py read for the
BCM43455c0 / 4358 / 4366c0; nsub = (len-18)/4). rvcsi_nx_csi_udp_write to
synthesize payloads for tests. rvcsi_nx_decode_chanspec — d11ac chanspec ->
channel (chanspec & 0xff) / bandwidth (bits [13:11], cross-checked against the
FFT size) / band (bits [15:14], cross-checked against the channel number).
Still allocation-free, bounds-checked, structured errors, never panics.
- ffi.rs wraps it: decode_chanspec / parse_nexmon_udp_header / decode_nexmon_udp
/ encode_nexmon_udp + DecodedChanspec / NexmonCsiHeader; every unsafe block
documented; the ABI guard now expects 1.1.
rvcsi-adapter-nexmon:
- pcap.rs — a dependency-free classic-libpcap reader (all four byte-order /
timestamp-resolution magics; Ethernet / raw-IPv4 / Linux-SLL link types;
tolerates a truncated final record; pcapng is a follow-up) + extract_udp_payload
+ a synthetic_udp_pcap / synthetic_nexmon_pcap test/example generator.
- NexmonPcapAdapter (a CsiSource) — reads the CSI UDP packets out of a
`tcpdump -i wlan0 dst port 5500 -w csi.pcap` capture, decodes each via the C
shim, stamps the frame timestamp from the pcap packet time; non-CSI packets
counted as "skipped" in health.
rvcsi-runtime: decode_nexmon_pcap, summarize_nexmon_pcap (+ NexmonPcapSummary:
link type, CSI frame count, channels, bandwidths, subcarrier counts, chip
versions, RSSI range, time span), CaptureRuntime::open_nexmon_pcap[_bytes].
rvcsi-node (napi-rs): nexmonDecodePcap, inspectNexmonPcap, decodeChanspec,
RvcsiRuntime.openNexmonPcap. @ruv/rvcsi SDK + .d.ts updated (NexmonPcapSummary,
DecodedChanspec). rvcsi-cli: `record --source nexmon-pcap`, `inspect-nexmon`,
`decode-chanspec`.
161 rvcsi tests pass (adapter-nexmon 9->22), 0 failures, clippy-clean.
ADR-096 §2.2/§2.3/§5, CHANGELOG, CLAUDE.md updated.
https://claude.ai/code/session_01CdYAPvRTjcch6YrYf42n1z
b116a99481