---
type: decision
tags: [parking, decisions]
sources: [parking-system-architecture]
updated: 2026-06-21
status: settled
---

# Standing Decisions (settled)

The decisions treated as settled in the design notes. (See [[parking-system-architecture]]
"Summary of standing decisions".)

- **Stack:** [[turborepo]] · [[fastify]] (Node) · [[react-vite-spa]] · [[sqlite]] +
  [[drizzle-orm]] · [[local-jwt-auth]]. All MIT/Apache/BSD — **no vendor lock, no rug-pull
  risk** (see [[payload-cms]]). Full table in [[technology-stack]].
  - **Scoped exception (2026-06-15):** the [[opencv-anpr-service]] — a **separate local process**,
    not linked into the app — **may use AGPL** components (plate/vehicle models). The exception is
    bounded to that process; the Node/React app stays strictly MIT/Apache/BSD. See
    [[vision-service]].
- **Platform:** a **dedicated, hardened Linux appliance** (LUKS + GRUB password + Secure Boot),
  **not Windows/WSL** — see [[disk-os-hardening]].
- **Desktop shell:** the operator UI ships as a **[[desktop-shell-tauri|Tauri v2]]** kiosk wrapper
  (chosen over Electron, 2026-06-21) — small footprint, no bundled Chromium to patch, and a
  deny-by-default native surface that fits [[threat-model|the booth-operator threat model]]. The
  shell stays **thin**: all privileged logic remains in [[fastify]]. One open dependency — the
  appliance's WebKitGTK version (see [[open-questions]] #11). Ships as a **`.deb`** (the AppImage
  bundles a runner's WebKitGTK and fails on the 26.04 booth — 2026-09-04); its backend address is
  **operator-entered at runtime**, not baked in; and **in-app updates are an admin-only action**
  behind the polkit password prompt (user, 2026-09-04) — never make that prompt passwordless.
- **Integrity:** append-only, hash-chained, **software-signed** event log
  ([[append-only-event-chain]]) — hardware-backed signing (a non-extractable key in the
  **[[tpm|TPM]]** or a **USB HSM**; the [[atecc608]] is [[open-questions|upcoming, not present]]) is
  the target that makes it unforgeable by a host owner ([[hardware-signer-options]]). **[[reconciliation]]
  is the anti-fraud control**; encryption protects only at-rest (see [[threat-model]]).
- **Access control:** the **[[dingtian-relay]]** relay+input controller, on an **isolated VLAN**
  ([[network-isolation]]). Chosen because its **inputs are decoupled from its relays**, enabling
  host-in-the-loop ticket-first entry — the resolution to [[access-controller-button-flow]].
  (The [[uhppote-controller]] and [[zkteco-controller]] were evaluated and **rejected** — kept as
  historical record. The [[esp32-custom-controller]] remains the documented prevention-grade
  alternative — the [[trust-boundary]] fork.)
- **Readers:** prefer [[wiegand]]-into-controller for permit holders (autonomous); host-in-the-loop
  for [[lpr-camera|LPR]]/QR/pure-network readers; both can share a relay (see
  [[entry-exit-readers]]).

Unsettled items live in [[open-questions]].