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julian 1efa77bf56 devices: pool-of-spaces model — drop lane, per-relay direction

A parking lot is one pool of spaces with a flexible set of entry/exit
points — no "lane". Direction is a property of each RELAY inside an access
controller; readers/cameras bind to a controller relay and inherit it.

Schema:
- drop `lane` from ledger_events, device_events, sessions
- rename lane_devices -> devices (no lane/direction columns)
- access config.relays=[{relay,direction,button?}]; reader/camera
  config.controllerId+relay binding
- fresh 0000_baseline migration (history reset; dev data was throwaway)

Signed ledger:
- remove `lane` from canonicalize(); bump signer keyId sw-hmac-v1 -> v2
  (v1 events won't verify under v2 — intentional, gated per-event by keyId)

Server:
- new device-resolve.ts (replaces lane-map.ts): relayForButton,
  relayForDevice, firstRelayByDirection, devicesByDirection
- entry-flow: button terminal -> its relay; exit/permit: reader's bound
  relay; dispatcher resolves the bound relay + inherited direction
- camera snapshots fire by direction site-wide, async, never block open
- DeviceConfig widened to nested JSON for relays[]

Web:
- wizard: no lane selector; add controllers (relay map + entry-button
  terminal) first, then bind readers/cameras/printers to a controller relay

Wiki: new entry-exit-points.md (replaces lane-direction); reworked
entry-exit-readers, parking-session, first-run-setup, device-registry,
append-only-event-chain, device-events; removed stale lane/LaneMap mentions.

2026-06-16 20:29:38 +02:00

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Printer roles & failover

A lane runs more than one printer, and the system knows each one's job so it can fail over automatically. This is a reliability decision, not a threat-model one: an entry ticket must still print when the outside dispenser jams or drops off the network.

Roles

Each printer instance (a devices row, category printer) declares a role in its config:

entry-dispenser — outside, at the lane. Prints the entry ticket the driver takes.
booth-receipt — inside the booth. Prints receipts at exit/payment, AND serves as the backup for entry tickets.

It also declares a failoverRank (higher = preferred within a role) to order multiple printers of the same role deterministically (ties broken by id).

Failover rule (asymmetric, on purpose)

For an entry ticket (wantRole = entry-dispenser): try the entry dispensers (best rank first), then fall back to the booth printer. So a driver still gets a ticket when the outside unit is offline — the operator hands it over from the booth.

The reverse is deliberately not done: a receipt never prints on the outside dispenser. Receipts are a booth-only job; an entry dispenser falling back to print receipts makes no physical sense.

Where the logic lives

The driver (rongta) is role-agnostic — role/rank are just config; the transport doesn't care. Keeps device-adapter-pattern swappable.
Selection is pure logic in packages/devices/printer-routing.ts: orderForRole() ranks candidates; printWithFailover() attempts the print down the list and throws NoPrinterAvailableError only when every candidate fails.
It attempts the print directly rather than racing a healthCheck first — the print is the real reachability test, and a health probe that passes can still be followed by a failed print.

Open: the all-printers-down policy

When printWithFailover exhausts every candidate, what should entry do — raise the barrier with no paper ticket (the plate/lpr-camera is the independent record), or hold? That policy belongs to the entry flow (device-input-flow, fail-state-safety), not the printer layer, and is not yet decided. The signed event (append-only-event-chain) is created regardless of whether paper prints.

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