In-park merchants discharge customers' parking: a merchant user scans the
ticket on their device (/validate; validation:create + program↔user binding)
and applies their program — comp / first-N-minutes free / amount-off (capped,
typed at scan) / percent. All money stays at the booth: the quote folds live
validations in a canonical order (timeCredit → percent → fixed → comp, net
floors at 0, Σ lines ≡ gross − net), the payment records gross/discount and
CONSUMES the validation ids (an overstay's fresh period never re-applies
them), the receipt prints the gross → lines → net story, and the Z/X-report
carries discountTotalMinor leakage. Every apply/void is a signed, attributed
ledger event (refId = append-only void); program config is /setup/site master
data (Bar/Lavazh checkboxes + right-column panel, tabs when both) whose saves
sign config_change. Migration 0024 + reset-db drift-guard entries; 8 route
integration tests + priceSession fold suite.
See wiki/concepts/validation-discounts.md for the full design record.
Claude-Session: https://claude.ai/code/session_01YYkpEsLmoQPaize5ec3oUm
"ALL 740 / 3h 2m" gave no derivation. explainFee in @parking/shared runs
the EXACT computeFee walk with an optional trace collector — one code
path, so Σ line items ≡ the amount by construction (golden V1 regression
byte-identical; instrumentation changes no fee). Items: contiguous
same-price increment runs (time window · N × unit · tier-card name),
window-package occurrences, stepped day totals (top-tier repeat
flagged), daily-cap clamps as NEGATIVE adjustments, entry grace.
/api/tariff/simulate returns `breakdown` (null when settled); the lab's
Outcome panel renders the lined table with a rounding note (raw min →
billed min at the increment — answers "why does 3h 2m bill as 4h") and
a total row. Works against active/historical versions and drafts alike,
so a night-package draft can be verified line by line before publish.
Largely delivers the wiki's open "composer price preview" item.
4 new engine tests pin the sum invariant + item shapes (97 shared green).
Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V
A windowed card can now charge ONE total for any presence in its window —
the real night rate ("20:00–07:00 = 400, leave earlier and it's still
400"), which the per-increment flatMinor could not express (park-buzi's
"night 400" card billed 400/HOUR). Engine charges once per contiguous run
of increments the card wins, tracked across rolling-day segments so a
night crossing the 24h boundary charges once; out-of-window increments
price by the base card as usual.
Operator decisions (2026-07-05): per-occurrence repeat (two nights = two
charges), any-touch-pays-full, windowed cards only (a base "price per
day" is a 1-row up-to table). Validator: mutually exclusive with
flat/blocks/steps, no per-card cap, forbidden on the defaultCard.
flatMinor docs clarified as PER INCREMENT. 6 new engine tests.
Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V
A stepped ("up-to") default card prices the whole stay as one total, so the V2
engine short-circuits to steppedFee and NEVER consults windowed cards — any
time/seasonal tiers would silently never fire. Found live: an active tariff had a
stepped base plus weekday-night + weekend tiers, and every 3h stay priced 600 ALL
regardless of hour/day because the tiers were dead.
- validateTariffV2 now rejects a stepped defaultCard combined with windowedCards,
with an actionable message (switch the base to ladder/flat, or remove the tiers).
- Composer shows an inline red warning the moment base mode is stepped and tiers
exist; publishing is blocked server-side regardless.
- ApiError now carries the server's problems[], so the publish error surfaces the
SPECIFIC reason instead of a generic "invalid tariff structure".
- 2 new validation tests (55 pass).
Wiki: tariff, log.
Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V
Owners often state rates as a total-by-duration matrix (0-1h=200, 0-3h=500,
0-6h=800, 0-9h=900, 0-12h=1000) that the marginal hourly ladder can't express
(the ladder sums per-increment rates; this is cumulative totals at thresholds).
Add STEPPED as a third pricing mode alongside the ladder and flat.
- @parking/shared: TariffStep {uptoMin, totalMinor} + a `steps[]` field on V1
structures and V2 cards (mutually exclusive with blocks/flatMinor). steppedFee():
smallest tier with uptoMin >= duration wins (INCLUSIVE boundary), the top tier
repeats as a per-day cap; wired into computeFeeV1 + computeFeeV2 (V2 default card
only — a whole-stay total can't be sliced per-increment by a windowed card).
Validation: ascending uptoMin, non-negative totals, no daily-cap-with-steps,
steps-only-on-default. priceSession/quote/booth/Lab price it via the shared core.
- Composer UI: a "By duration (up-to)" mode with an up-to/total table (base card
only). i18n modeStepped/steppedHint/stepUpTo/stepTotal/addStep (sq+en).
- 8 new unit tests incl. the exact owner matrix, multi-day repeat, overstay, and
validation (53 pass). Verified end-to-end via the UI: authored + published the
matrix, Tariff Lab prices it exactly (3h->500, 6h->800, 12h->1000, 2d->2000).
Wiki: tariff (three pricing modes + stepped semantics), log.
Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V
Test rates "in time" (overnight windows, daily caps, overstay) in seconds against
any tariff version, instead of waiting hours/days. No real ledger writes.
- Extract priceSession() into @parking/shared: the grace/overstay wrapper over
computeFee (unpaid -> entry..now; within-grace -> settled 0; grace-expired ->
overstay, a fresh period from grace-expiry). PayStation.quote() now calls it so
the booth and the lab can never diverge.
- API (tariffs.ts, tariff:read, read-only): POST /api/tariff/simulate prices a
hypothetical session (active/any version/inline structure) and returns the
priceSession outcome + a 30m..3d duration curve (see where the daily cap flattens);
GET /api/tariff/simulate/session/:identity prefills from a real ledger session.
- UI TariffLab.tsx at Setup -> "Tariff Lab": version picker, entry/asOf times,
optional payment+grace, category, and load-a-real-ticket. Admin-gated, available
on-site (useful to quote a dispute).
- 4 new priceSession unit tests incl. the ticket-1245791632490 overstay-not-zero
regression (40 pass). i18n lab.* + nav.tariffLab (sq+en). Verified live via the UI.
Wiki: tariff (priceSession + Tariff Lab as-built), log.
Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V
Bring the legacy ParkSQL2017 pricing BREADTH onto our engine while keeping
integer-minor-unit money + immutable signed versions (rejecting legacy's
float money / mutable rows). TariffStructure becomes a discriminated union:
V1 = the original bare ladder (UNCHANGED, verbatim algorithm, golden-
regression-tested against the live version); V2 = {version:2, tz, shared
knobs, defaultCard, windowedCards[]} where each card is flat OR a block
ladder and may be scoped by wall-clock hour window / day-of-week / date
range / vehicle category.
computeFeeV2 prices by stepping one increment at a time, advancing the
ladder by ELAPSED minutes (continuous) while selecting the active card by
WALL-CLOCK time in the version's FROZEN tz. Decisions: tz is a per-site
setting (site_config.timezone, default Europe/Tirane) stamped server-side
into each version on publish — never the host clock (reproducibility);
default-card cap governs a mixed day; precedence = specificity
(date>dow>hour) -> priority -> name (total, order-independent), validation
rejects ambiguous ties; category = a card FIELD, frozen in the signed
vehicle_entry payload (site_config.default_vehicle_category default), read
at both pricing call-sites.
Composer: default card front-and-centre (flat/ladder toggle), tiers under
an "Advanced" disclosure; emits BARE V1 when no tiers (back-compat). DB:
migrations 0005 (timezone) + 0006 (default_vehicle_category). Stood up
vitest in @parking/shared (was zero tests on the ledger-feeding fee fn);
36 tests incl. golden V1 regression, happy-hour/overnight/dow/flat/category/
cap edges, precedence shuffle-invariance, Europe/Tirane DST determinism,
validation matrix — all green. No event-chain change.
Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V
julian