fix(paired-data): 4 bugs corrupting/blocking camera-supervised training data (#1007)

1. record-csi-udp.py stamped LOCAL time with a 'Z' (UTC) suffix → camera/CSI disagreed
   by the UTC offset → 0 aligned pairs. Now writes true UTC via datetime.now(timezone.utc).
2. align-ground-truth.js kept empty-keypoint (non-detection) records at confidence 0,
   collapsing window avgConf below threshold → all windows rejected. Now skipped at load.
3. extractCsiMatrix silently zero-padded/truncated mixed-subcarrier frames. Now frames
   are filtered to the session's modal subcarrier count before windowing — never padded.
4. CSI/feature matrices are filled frame-major but were labeled shape [nSc, nFrames] —
   transposed. Labels corrected to [nFrames, nSc] / [nFrames, dim].

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

scripts/align-ground-truth.js

@@ -184,7 +184,9 @@ function loadGroundTruth(filePath) {
   const raw = loadJsonl(filePath);
   const frames = [];
   for (const r of raw) {
-    if (r.ts_ns == null || !r.keypoints) continue;
+    // Skip non-detection frames (empty keypoints []) — they must not dilute window
+    // confidence; confidence stats are over actual detections only (#1007 Bug 2).
+    if (r.ts_ns == null || !r.keypoints || r.keypoints.length === 0) continue;
     frames.push({
       tsMs: cameraTsToMs(r.ts_ns),
       keypoints: r.keypoints,
@@ -266,7 +268,29 @@ function loadCsi(filePath) {
   // Sort by timestamp
   rawCsi.sort((a, b) => a.tsMs - b.tsMs);
   features.sort((a, b) => a.tsMs - b.tsMs);
-  return { rawCsi, features };
+
+  // Bug 3 (#1007): keep only frames at the session's MODAL subcarrier count so windows
+  // are homogeneous; never silently zero-pad/truncate the off-format frames the ESP32
+  // emits (HT20/HT40/fragments). extractCsiMatrix then sees uniform-width frames.
+  return { rawCsi: filterToModalSubcarriers(rawCsi), features };
+}
+
+/**
+ * Keep only frames whose subcarrier count equals the session's modal (most common)
+ * count. Off-format frames are dropped (logged), not padded — prevents the silent
+ * zero-padding that corrupted windows in #1007.
+ */
+function filterToModalSubcarriers(frames) {
+  if (frames.length === 0) return frames;
+  const counts = new Map();
+  for (const f of frames) counts.set(f.subcarriers, (counts.get(f.subcarriers) || 0) + 1);
+  let modal = frames[0].subcarriers, best = 0;
+  for (const [sc, n] of counts) if (n > best) { best = n; modal = sc; }
+  const kept = frames.filter((f) => f.subcarriers === modal);
+  if (kept.length !== frames.length) {
+    console.error(`[align] #1007: kept ${kept.length}/${frames.length} CSI frames at modal subcarrier count ${modal} (dropped ${frames.length - kept.length} off-format; no silent padding)`);
+  }
+  return kept;
 }
 
 // ---------------------------------------------------------------------------
@@ -343,7 +367,8 @@ function averageKeypoints(cameraFrames) {
 
 /**
  * Extract CSI amplitude matrix from raw_csi window.
- * Returns { data: flat Float32Array, shape: [subcarriers, windowFrames] }.
+ * Fill is frame-major (matrix[f*nSc + s]), so shape is [windowFrames, subcarriers]
+ * (#1007 Bug 4 — was mislabeled [subcarriers, windowFrames], transposing consumers).
  */
 function extractCsiMatrix(window) {
   const nFrames = window.length;
@@ -363,12 +388,13 @@ function extractCsiMatrix(window) {
     }
   }
 
-  return { data: Array.from(matrix), shape: [nSc, nFrames] };
+  return { data: Array.from(matrix), shape: [nFrames, nSc] };
 }
 
 /**
  * Extract feature matrix from feature-type window.
- * Returns { data: flat array, shape: [featureDim, windowFrames] }.
+ * Fill is frame-major (matrix[f*dim + d]), so shape is [windowFrames, featureDim]
+ * (#1007 Bug 4 — was mislabeled [featureDim, windowFrames]).
  */
 function extractFeatureMatrix(window) {
   const nFrames = window.length;
@@ -382,7 +408,7 @@ function extractFeatureMatrix(window) {
     }
   }
 
-  return { data: Array.from(matrix), shape: [dim, nFrames] };
+  return { data: Array.from(matrix), shape: [nFrames, dim] };
 }
 
 // ---------------------------------------------------------------------------

scripts/record-csi-udp.py

@@ -15,6 +15,7 @@ import os
 import socket
 import struct
 import time
+from datetime import datetime, timezone
 
 
 def parse_csi_packet(data):
@@ -41,7 +42,8 @@ def parse_csi_packet(data):
 
     return {
         "type": "raw_csi",
-        "timestamp": time.strftime("%Y-%m-%dT%H:%M:%S.") + f"{int(time.time() * 1000) % 1000:03d}Z",
+        # true UTC, not local-time-labeled-Z (#1007 Bug 1) — e.g. "2026-06-17T01:23:45.678Z"
+        "timestamp": datetime.now(timezone.utc).isoformat(timespec="milliseconds").replace("+00:00", "Z"),
         "ts_ns": time.time_ns(),
         "node_id": node_id,
         "rssi": rssi,