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Decision log

Metrica keeps a durable decision log. Every choice that outlives today’s task — a library, an architecture pattern, an API shape, or a deliberate not-to-do — is written up in the repo under /decisions/YYYY-MM-DD-{topic}.md using a fixed template (Decision / Context / Alternatives / Reasoning / Trade-offs).

Architecture & data

Section titled “Architecture & data”
Date Decision Gist
2026-07-02 Auth ↔ data split Supabase Auth for identity only; app data in Neon Postgres. stores.owner_id = Supabase user UUID; no cross-system FK.
2026-07-02 Track identity The raw ByteTrack int is never a foreign key. MVP drops the tracks table; tracker_id is a debug column scoped to camera_id.
2026-07-03 Store-local rollups Daily/hourly rollups computed in each store’s local timezone (Store.timezone), not UTC.
2026-07-04 Little’s Law dwell Average visit = area under the occupancy curve ÷ entries — no sessions table, no per-person tracking.

CV worker & counting

Section titled “CV worker & counting”
Date Decision Gist
2026-07-02 Single-line counting MVP counts crossings with one virtual line (2D cross-product + sign flip) + invert flag. Two-line tripwire deferred to Phase 2.
2026-07-02 YOLO license deferred Use Ultralytics YOLO (AGPL) for MVP; swap to an Apache-2.0 detector before the first proprietary sale. Still open.
2026-07-03 Multi-camera counting Footfall only on cameras flagged is_counting_line; no cross-camera Re-ID (count crossings/occupancy, not unique visitors).
2026-07-03 Free-threaded Python Stay on standard CPython; do not adopt the no-GIL build until CPU-worker scale + stable CV wheels justify it.

Infra & deployment

Section titled “Infra & deployment”
Date Decision Gist
2026-07-02 Deployment stack Cloudflare Pages (frontends) · FastAPI backend · Neon · Supabase Auth. (Backend host later superseded — see below.)
2026-07-04 Backend on FastAPI Cloud Move backend to FastAPI Cloud (fastapi deploy); enforce migrations from GitHub Actions (migrate-then-deploy). Supersedes the Render line.

Frontend & apps

Section titled “Frontend & apps”
Date Decision Gist
2026-07-03 Frontend vitest config Dedicated vitest.config.ts (no Cloudflare plugin) so the test runner starts.
2026-07-04 i18n (en/fr/ar) i18next + react-i18next in frontend + landing; ar = Tunisian Darja (RTL), not MSA.
2026-07-04 Keep snapshotUrl until B5 Keep the unauth snapshot helper alongside the new authed blob fetch until calibrate.tsx switches over.
2026-07-04 Owner invite email Admin assigns owner by email → backend sends a Supabase magic-link invite (no direct Resend call).
2026-07-04 shadcn zinc dashboard Adopt shadcn/ui (new-york, zinc); retire the custom island palette on the dashboard.

Product, brand & docs

Section titled “Product, brand & docs”
Date Decision Gist
2026-07-04 Product name Ship the pilot as Metrica on metrica.vision (provisional; revisit after pilot #1). Known Yandex Metrica collision accepted.
2026-07-05 Docs site This site — Astro Starlight on Cloudflare Pages; read-mostly, engineering-authored.