fix(bf-39mli): co-locate Alice CSI blob with triangulated point so matcher clears f_distance

The BLE identity matcher never attached Alice's triangulated device to a CSI
blob (matchConf stayed below MinMatchConfidence=0.60). Two compounding root
causes, both verified via [BLEDBG] instrumentation (SPAXEL_BLE_DEBUG):

1. RSSI round-trip inconsistency (cmd/sim/main.go): the sim emitted RSSI under
   a different log-distance path-loss model (-50-20log10(d)) than the matcher
   inverts (internal/ble: RefRSSI=-65, PathLossExp=2.5 -> rssiToDistance at
   identity.go:376). rssiToDistance then systematically underestimated true
   distance (~0.22x), triangulating every device too close to the node cluster
   and off its CSI blob. The BLE key was also "rssi" instead of "rssi_dbm",
   which ingestion maps to, leaving RSSIdBm at 0 and collapsing triangulation.
   Now emit under the matcher's own model constants and the "rssi_dbm" key, so
   rssiToDistance inverts RSSI back to the true node->walker distance.

2. Axis convention (identity.go): horizontal blob distance was computed over
   (X,Z), but Z is the height axis -- triangulated Z is pinned to the anchor
   mounting plane while the CSI blob centroid sits at person height (~1m), so
   (X,Z) misread that vertical gap as horizontal distance and suppressed the
   distance gate. Use the (X,Y) floor plane, matching createBLEOnlyTracks and
   the sim/fusion runtime convention (X,Y floor; Z up).

The [BLEDBG] instrumentation (bleDebug/SPAXEL_BLE_DEBUG gate + log lines) is
retained as live matcher diagnostics.

Verified (HEAD, uncommitted, independently re-run):
- SPAXEL_BLE_DEBUG=1 scripts/run-sim-ble-match.sh -> PASS:
  blob_id=7 conf=0.7139527093753523, [BLEDBG] assign hDist=0.61m matchConf=0.714
  (gate 0.60), reject_in_sim_log=0, peak_blobs=2.
- scripts/run-sim-local.sh -> PASS: peak_blob_count=2, reject_in_sim_log=0,
  sim --verify PASSED, 4 nodes online, fps 363 (no base-blob-path regression).
- go vet ./mothership/... + go build ./mothership/... + cmd/sim -> clean.

Co-Authored-By: Claude <noreply@anthropic.com>
Bead-Id: bf-39mli

mothership/cmd/sim/main.go

@@ -24,6 +24,7 @@ import (
 	"time"
 
 	"github.com/gorilla/websocket"
+	"github.com/spaxel/mothership/internal/ble"
 	"github.com/spaxel/mothership/internal/simulator"
 )
 
@@ -1133,15 +1134,28 @@ func sendBLEMessages(nodes []*VirtualNode, walkers []*Walker) {
 			dz := walker.Position.Z - node.Position.Z
 			dist := math.Sqrt(dx*dx + dy*dy + dz*dz)
 
-			rssi := -50.0 - 20.0*math.Log10(dist/1.0)
+			// RSSI MUST be emitted under the matcher's OWN log-distance path-loss
+			// model (internal/ble: RefRSSI, PathLossExp, RefDistance) so the matcher's
+			// rssiToDistance(rssi) inverts RSSI back to the TRUE node→walker distance.
+			// A mismatched model (the old -50-20*log10(d)) made rssiToDistance
+			// systematically underestimate distance (~0.25x), triangulating every
+			// device too close to the node cluster and landing it off its CSI blob, so
+			// the identity match never cleared MaxBLEBlobDistance/MinMatchConfidence
+			// (bf-1yr1w). Mirroring the matcher's constants here guarantees round-trip.
+			rssi := float64(ble.RefRSSI) - 10.0*ble.PathLossExp*math.Log10(dist/ble.RefDistance)
 			if rssi < -90 {
 				rssi = -90
 			}
 
+			// RSSI key MUST be "rssi_dbm" to match ingestion.BLEDevice's JSON tag
+			// (internal/ingestion/message.go) and the documented node→mothership BLE
+			// protocol. Emitting "rssi" silently left RSSIdBm at its zero value, so
+			// rssiToDistance(0) collapsed triangulation to ~2.5mm-from-every-node and
+			// the identity matcher never cleared MinMatchConfidence (bf-1yr1w).
 			devices = append(devices, map[string]interface{}{
-				"addr": fmt.Sprintf("AA:BB:CC:DD:EE:%02X", walker.ID),
-				"rssi": int(rssi),
-				"name": fmt.Sprintf("sim-person-%d", walker.ID),
+				"addr":     fmt.Sprintf("AA:BB:CC:DD:EE:%02X", walker.ID),
+				"rssi_dbm": int(rssi),
+				"name":     fmt.Sprintf("sim-person-%d", walker.ID),
 			})
 		}
 

mothership/internal/ble/identity.go

@@ -3,11 +3,15 @@ package ble
 import (
 	"log"
 	"math"
+	"os"
 	"reflect"
 	"sync"
 	"time"
 )
 
+// bleDebug reports whether SPAXEL_BLE_DEBUG is set (live matcher diagnostics).
+func bleDebug() bool { return os.Getenv("SPAXEL_BLE_DEBUG") != "" }
+
 // Triangulation parameters per specification
 const (
 	RefDistance    = 1.0 // d0 = 1.0m reference distance
@@ -202,6 +206,16 @@ func (m *IdentityMatcher) triangulateAllDevices(now time.Time) []*TriangulatedDe
 
 		// Triangulate position
 		pos, conf, residual := m.triangulate(readings)
+		if bleDebug() {
+			log.Printf("[BLEDBG] triangulate addr=%s readings=%d pos=(%.2f,%.2f,%.2f) conf=%.3f residual=%.3f",
+				addr, len(readings), pos.X, pos.Y, pos.Z, conf, residual)
+			for _, r := range readings {
+				nx, ny, nz, ok := m.nodePos.GetNodePosition(r.NodeMAC)
+				d := rssiToDistance(r.RSSIdBm)
+				log.Printf("[BLEDBG]   reading node=%s rssi=%d dist=%.2f nodepos=(%.2f,%.2f,%.2f) ok=%v",
+					r.NodeMAC, r.RSSIdBm, d, nx, ny, nz, ok)
+			}
+		}
 		if conf < 0.1 {
 			continue // Too low confidence
 		}
@@ -399,8 +413,13 @@ func (m *IdentityMatcher) assignBLEToBlobs(devices []*TriangulatedDevice, blobs
 				continue
 			}
 
-			// Horizontal distance (ignore Y/height for BLE since antenna height is variable)
-			hDist := math.Sqrt(math.Pow(td.Position.X-b.X, 2) + math.Pow(td.Position.Z-b.Z, 2))
+			// Horizontal distance over the floor plane (X,Y). Z is the height axis:
+			// the triangulated Z is pinned to the anchor mounting plane (all nodes share
+			// a height, so Z is degenerate) and the CSI blob centroid sits at person
+			// height (~1m). Using Z here would misread that vertical gap as horizontal
+			// distance and suppress f_distance. Matches the floor-plane convention used
+			// by createBLEOnlyTracks below and by the sim/fusion runtime (X,Y floor; Z up).
+			hDist := math.Sqrt(math.Pow(td.Position.X-b.X, 2) + math.Pow(td.Position.Y-b.Y, 2))
 
 			if hDist < bestDist {
 				bestDist = hDist
@@ -409,6 +428,10 @@ func (m *IdentityMatcher) assignBLEToBlobs(devices []*TriangulatedDevice, blobs
 		}
 
 		if bestBlob == nil {
+			if bleDebug() {
+				log.Printf("[BLEDBG] assign addr=%s NO blob within %.1fm (td pos=(%.2f,%.2f,%.2f) conf=%.3f nodes=%d)",
+					td.Device.Addr, MaxBLEBlobDistance, td.Position.X, td.Position.Y, td.Position.Z, td.Confidence, td.NodeCount)
+			}
 			continue
 		}
 
@@ -426,6 +449,13 @@ func (m *IdentityMatcher) assignBLEToBlobs(devices []*TriangulatedDevice, blobs
 
 		// Compute match confidence
 		matchConf := computeMatchConfidence(td, bestDist)
+		if bleDebug() {
+			// TEMP (bf-6d2ii): log blob centroid (X,Y) vs triangulated (X,Y) to
+			// quantify the geometric divergence. Revert after diagnosis.
+			log.Printf("[BLEDBG] assign addr=%s blob=%d hDist=%.2fm matchConf=%.3f (gate=%.2f) tdconf=%.3f nodes=%d resid=%.3f tdXY=(%.2f,%.2f) blobXY=(%.2f,%.2f) nBlobs=%d",
+				td.Device.Addr, bestBlob.ID, bestDist, matchConf, MinMatchConfidence, td.Confidence, td.NodeCount, td.Residual,
+				td.Position.X, td.Position.Y, bestBlob.X, bestBlob.Y, len(blobs))
+		}
 		if matchConf < MinMatchConfidence {
 			continue
 		}