Behavision: face recognition for retail, edge to head office

Five components that ship as one product:

- behavision/  the recognition engine. RTSP ingest, YuNet detection, IoU
               tracking, ArcFace embeddings, a FAISS/SQLite gallery, and a
               FastAPI dashboard. Identity is decided once per TRACK from an
               average of at least three embeddings, never per frame.
- agent/       the Go edge agent: supervises the engine, holds a durable
               spool, and drains it to MQTT. Nothing is acked before the
               broker confirms.
- desktop/     the shop PC application (Wails + React + tray).
- server/      the cloud API, MQTT consumer, reports and assistant.
- web/         platform.loyaly.ai, the head-office app, embedded in the
               server binary.

The gallery stores 512-float embeddings and timestamps - no images unless
`app.store_faces` is switched on. Those embeddings are biometric personal
data under GDPR and India's DPDP: template inversion reconstructs a
recognisable face from an ArcFace vector, so data/behavision.db is treated
as a biometric database and DELETE /api/visitors/{id} is a real erasure.

CLAUDE.md carries the reasoning behind every non-obvious decision here,
including the ones that were measured and the ones that were wrong first.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HViLj9gYNRtSr7YVZmW5sn

behavision/log.py

@@ -0,0 +1,28 @@
+"""Central logging setup: console + rotating file, no print() anywhere."""
+from __future__ import annotations
+
+import logging
+import logging.handlers
+from pathlib import Path
+
+_FORMAT = "%(asctime)s %(levelname)-7s %(name)s: %(message)s"
+
+
+def setup_logging(level: str = "INFO", data_dir: "Path | None" = None) -> None:
+    root = logging.getLogger()
+    if root.handlers:  # already configured (tests, reload)
+        return
+    root.setLevel(getattr(logging, level.upper(), logging.INFO))
+
+    console = logging.StreamHandler()
+    console.setFormatter(logging.Formatter(_FORMAT))
+    root.addHandler(console)
+
+    if data_dir is not None:
+        log_dir = Path(data_dir) / "logs"
+        log_dir.mkdir(parents=True, exist_ok=True)
+        fileh = logging.handlers.RotatingFileHandler(
+            log_dir / "behavision.log", maxBytes=5_000_000, backupCount=3,
+            encoding="utf-8")
+        fileh.setFormatter(logging.Formatter(_FORMAT))
+        root.addHandler(fileh)