julian
727c62da90
- site_config gains optional park identity (park_name, operator_name, nius, address, phone, email); additive Drizzle migration 0001. GET/PUT /api/site-config read/write the full config (PUT partial patch, admin only); SiteSettings + SetupWizard expose the fields. - renderTicket() prints an Albanian header sourced from site_config, the all-numeric 13-digit ticket id (12 random + Luhn) as Code128, large digits, and a lost-ticket footer. CP852 codepage so ë/ç render. - Widen the Code128 module width 2->3 and height 80->100 dots so the short-range "Simple" QR/barcode reader decodes reliably (was barely reading at module width 2 on the 80mm head). See wiki/concepts/site-metadata.md and ticket-encoding.md.
86 lines
5.4 KiB
Markdown
86 lines
5.4 KiB
Markdown
---
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type: concept
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tags: [parking, domain, business, devices, entry-flow]
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sources: []
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updated: 2026-06-15
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status: open
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---
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# Ticket Encoding & Scanning
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How a transient [[parking-session]]'s **ticket id** is printed, carried by the customer, and read
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back at the pay station and exit. This is the **physical backbone of the transient flow** — the
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thing that links entry → pay → exit when there's no plate.
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## The ticket id is the session key
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At entry the system mints a `vehicle_entry` event with a **ticket id** (`identity`) and prints a
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ticket the customer keeps. That same id is read back later to find the session. Properties the id
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must have:
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- **Opaque + unguessable** — a random id (not a sequential count an attacker could iterate to claim
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someone else's cheaper session). Sequential **physical** stock numbering is a separate
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reconciliation aid ([[reconciliation]] pre-numbered stock), not the scan key.
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- **All-numeric** (as-built 2026-06-17) — so ANY legacy 1D barcode scanner reads it and an operator
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can hand-key it. Random (not sequential), so "all-numeric" does not weaken the unguessable
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property. Format: **13 digits = 12 cryptographically-random digits + 1 Luhn check digit**
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(10^12 space → negligible collisions at lot scale; the Luhn digit lets manual entry reject a typo
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rather than fail as "session not found"). `newTicketId()` in `apps/server/src/entry-flow.ts`;
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validate with `validateTicketCode()` (gate MANUAL entry only — a scanned/looked-up id already in
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the ledger is authoritative regardless of format).
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- **Format is a property of minting, not the schema** — `identity` / `sessions.id` are free-form
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`text`, so changing the id format is a code change with **no migration**. Legacy `T-<uuid>` ids
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(pre-2026-06-17) remain valid keys and coexist with numeric ones.
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- **Single logical session** — scanning it at the pay station finds the open session; after payment
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it's the proof-of-paid the exit checks.
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## Encoding: Code128 numeric barcode — printed by the booth dispenser
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- The [[rongta-printer]] prints the ticket id as a **1D Code128 barcode** (the all-numeric code),
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with the **same code in large human-readable digits below it**, then the entry time. Code128 over
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QR for the primary symbology because the booth's reader hardware is unknown and a legacy 1D laser
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scanner is the lowest common denominator — and the printed digits mean total reader failure still
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leaves a hand-keyable code. A **QR for phone/imager scanning may be added later behind an admin
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toggle** (deferred — see Open).
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> **As-built (2026-06-17).** `renderTicket()` in [[rongta-printer]]
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> (`packages/devices/src/drivers/printer-rongta.ts`) emits the Code128 via ESC/POS `GS k` (code set
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> B) — **rendered by the printer firmware**, so there is no image-rendering step and no new
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> dependency (keeps the MIT/Apache/BSD constraint). Resilience rationale: the booth's reader is
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> uncertain, so the id is carried in two independently-readable forms (1D barcode / printed digits).
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> The "operator scans with a phone" path reuses the
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> existing dispatch flow ([[entry-exit-readers]]) and is tracked separately (not yet built).
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- **Scan points** (both host-side reads — [[entry-exit-readers]]):
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- **Pay station** — customer scans the ticket → host finds the session → shows fee → takes
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payment ([[tariff]], pay-on-foot) → appends `payment`.
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- **Exit lane** — customer scans the (now paid) ticket → host validates paid + within
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`gracePeriodExit` → `vehicle_exit` → `pulseOpen`.
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- The **scanner is a device behind an adapter** ([[device-adapter-pattern]]): a new `ReaderDevice`
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kind (QR/barcode imager) — likely the same `IdentitySource = "ticket"` / `"qr"` path. Keeps the
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app device-agnostic; hardware model is procurement ([[bom]], [[open-questions]]).
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- **On hand:** the **[[gee-qr-er80]]** QR access reader (`-Q-W`: QR scanner, Wiegand/RS-232/RS-485,
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Linux-supported) — the concrete scanner for this path. A serial `ReaderDevice` adapter feeds the
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`read` bus; pending the reader's RS-232 frame/baud (see [[gee-qr-er80]] open questions).
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## Ticketless alternative (plate as the ticket)
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Where the [[opencv-anpr-service|vision service]]/LPR captures the plate, the **plate can be the
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session key** instead of a printed ticket — drive in, plate read, drive to pay station and enter
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plate (or it's looked up), pay, exit by plate. No paper. The two can coexist per lane
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([[entry-exit-readers]] "both share a relay"); a printed QR ticket is the fallback when a plate
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isn't captured or is low-confidence (recognition is advisory — [[opencv-anpr-service]]).
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## Open
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- Primary symbology **decided**: Code128 set B over the all-numeric id (as-built above). Still open:
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what *else* prints (site name, tariff summary, help number).
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- **Optional QR (deferred)** — an admin toggle to ALSO print a QR for phone/imager users. The
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`code128()`/`qrCode()` ESC/POS helpers were prototyped 2026-06-16; QR was dropped 2026-06-17 in
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favor of "1D barcode + hand-keyable numeric code" because the booth's reader hardware is unknown.
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Revisit when mobile scanning is wanted.
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- **Phone-scan fallback** (operator scans a ticket with a phone when a reader is down) — designed
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but not built: an authenticated route feeding the same dispatcher + a minimal mobile scan UI.
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- Scanner hardware (imager model; same unit at pay station and exit?).
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- Lost/damaged ticket → the lost-ticket path ([[parking-session]], [[tariff]] admin-arbitrary
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amount).
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