fix(host): 256-bin HE-LTF ingest end-to-end + latent offset bugs (#1005)

Audit of every ADR-018 consumer against live C6 HE20 frames (532B/256-bin):
- sensing-server + CLI calibrate parsers read n_subcarriers from one byte
  (256 decoded as 0) with stale seq/rssi offsets (rssi always 0 — latent,
  pre-existing, confirmed vs firmware csi_collector.c). Fixed to the real
  ADR-018 layout; n_subcarriers u8->u16; byte 18 surfaced as typed PpduType.
- sensing-server probe buffer 256B -> 2048B (532B datagram errored on Windows)
- per-node grid gate: lock densest (n_subcarriers, ppdu_type) grid, re-warm
  on upgrade, skip sparser minority frames — HT-64 never mixes into an
  HE-256 baseline window
- hardware parser: HE-aware bandwidth classification (256-FFT HE20 = 20MHz,
  was Bw160); PpduType/Adr018Flags re-exported
- verbatim live frames (532B HE-SU, 148B HT) embedded as regression fixtures
- archive python parser: bandwidth heuristic mirror fix

Live-validated: calibrate --tier he20 consumed 600x 256-bin frames into an
ADR-135 He20 baseline (242 tones) skipping 94 HT frames; sensing-server
shows node 12 active with real RSSI (-40dBm). 765 tests green across the
three crates; workspace check clean; Python proof PASS.

Co-Authored-By: claude-flow <ruv@ruv.net>

v2/crates/wifi-densepose-sensing-server/tests/multi_node_test.rs

@@ -13,19 +13,19 @@ use std::time::Duration;
 
 /// Build a minimal valid ESP32 CSI frame (magic 0xC511_0001).
 ///
-/// Format (ADR-018):
-///   [0..3]  magic: 0xC511_0001 (LE)
-///   [4]     node_id
-///   [5]     n_antennas (1)
-///   [6]     n_subcarriers (e.g., 32)
-///   [7]     reserved
-///   [8..9]  freq_mhz (2437 = channel 6)
-///   [10..13] sequence (LE u32)
-///   [14]    rssi (signed)
-///   [15]    noise_floor
-///   [16..19] reserved
-///   [20..]  I/Q pairs (n_antennas * n_subcarriers * 2 bytes)
-fn build_csi_frame(node_id: u8, seq: u32, rssi: i8, n_sub: u8) -> Vec<u8> {
+/// Format (ADR-018, authoritative: firmware `csi_collector.c`):
+///   [0..3]   magic: 0xC511_0001 (LE)
+///   [4]      node_id
+///   [5]      n_antennas (1)
+///   [6..7]   n_subcarriers (LE u16 — 256 for ESP32-C6 HE-SU, issue #1005)
+///   [8..11]  freq_mhz (LE u32, 2437 = channel 6)
+///   [12..15] sequence (LE u32)
+///   [16]     rssi (signed)
+///   [17]     noise_floor
+///   [18]     PPDU type (ADR-110: 0=HT/legacy, 1=HE-SU)
+///   [19]     flags (ADR-110)
+///   [20..]   I/Q pairs (n_antennas * n_subcarriers * 2 bytes)
+fn build_csi_frame(node_id: u8, seq: u32, rssi: i8, n_sub: u16) -> Vec<u8> {
     let n_pairs = n_sub as usize;
     let mut buf = vec![0u8; 20 + n_pairs * 2];
 
@@ -35,18 +35,19 @@ fn build_csi_frame(node_id: u8, seq: u32, rssi: i8, n_sub: u8) -> Vec<u8> {
 
     buf[4] = node_id;
     buf[5] = 1; // n_antennas
-    buf[6] = n_sub;
-    buf[7] = 0;
+    buf[6..8].copy_from_slice(&n_sub.to_le_bytes());
 
     // freq = 2437 MHz (channel 6)
-    let freq: u16 = 2437;
-    buf[8..10].copy_from_slice(&freq.to_le_bytes());
+    let freq: u32 = 2437;
+    buf[8..12].copy_from_slice(&freq.to_le_bytes());
 
     // sequence
-    buf[10..14].copy_from_slice(&seq.to_le_bytes());
+    buf[12..16].copy_from_slice(&seq.to_le_bytes());
 
-    buf[14] = rssi as u8;
-    buf[15] = (-90i8) as u8; // noise floor
+    buf[16] = rssi as u8;
+    buf[17] = (-90i8) as u8; // noise floor
+    buf[18] = u8::from(n_sub >= 256); // ADR-110 PPDU type: HE-SU for 256-bin
+    buf[19] = 0; // ADR-110 flags
 
     // Generate I/Q pairs with node-specific patterns.
     // Different nodes produce different amplitude patterns so the server
@@ -136,7 +137,7 @@ fn test_multi_node_udp_send() {
     sock.set_write_timeout(Some(Duration::from_millis(100)))
         .ok();
 
-    let n_sub = 32u8;
+    let n_sub = 32u16;
     let node_ids = [1u8, 2, 3, 5, 7];
 
     for &nid in &node_ids {
@@ -161,11 +162,13 @@ fn test_multi_node_udp_send() {
 /// size for various subcarrier counts (boundary testing).
 #[test]
 fn test_frame_sizes() {
-    for n_sub in [1u8, 16, 32, 52, 56, 64, 128] {
+    // 256 = ESP32-C6 HE-SU grid (issue #1005) → 532-byte frame as on the wire.
+    for n_sub in [1u16, 16, 32, 52, 56, 64, 128, 256] {
         let frame = build_csi_frame(1, 0, -50, n_sub);
         let expected = 20 + (n_sub as usize) * 2;
         assert_eq!(frame.len(), expected, "wrong size for n_sub={n_sub}");
     }
+    assert_eq!(build_csi_frame(1, 0, -50, 256).len(), 532);
 }
 
 /// Simulate a mesh of N nodes sending frames at different rates.