The punktfunk/1 speed test was unusable across every client/host: at the start of
a burst a little data got through, then everything read as dropped (~10 MB total).
Two compounding bugs:
1. Receive side measured throughput from fully-reassembled FLAG_PROBE *access
units* only. The instant loss crossed the 20% FEC budget no AU completed, so the
figure cliffed to 0 / 100% loss even though most bytes still arrived — a binary
cliff, not a graded measurement.
2. Send side blasted each filler AU (up to 256 KB ≈ 200 packets) into the socket
buffer in one unpaced batch, unlike the real video path which paces. On a small
buffer (e.g. the Steam Deck's 416 KB) a single AU overflowed it, so the test
measured self-inflicted buffer overflow instead of the link.
Fixes:
- Host `run_probe_burst` keeps each AU a small (~16 KB) burst and paces by the byte
budget, mirroring `paced_submit`; reports the WIRE packets the kernel accepted and
the ones the send buffer dropped (stat deltas), separating host-side drops from
link loss.
- `ProbeResult` gains `wire_packets_sent` + `send_dropped` (back-compat decode: a
21-byte pre-wire-stats result still decodes, new fields 0).
- Clients (probe + connector) count delivered traffic at the packet level via
`session.stats()` deltas over the burst window, so throughput/loss degrade
gracefully. Connector freezes the delivered figure when the host report lands so
resumed video can't inflate it. New `ProbeOutcome`/`PunktfunkProbeResult` fields:
`host_drop_pct`, `wire_packets_sent`, `send_dropped`.
Validated on loopback (graded 142→1391 Mbps, host_drop/link_loss split correctly,
no cliff) and live against the Deck: clean to ~200 Mbps goodput / 273 Mbps wire at
0% link loss, host send buffer the wall above that (the lever-#1 target).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
enricobuehler
f37a304fba