julian
8a8e74561d
Pivot from the hardware/integrity layer to the parking operation. All wiki-only; no code yet. Core principle throughout: business entities are projections over the signed append-only event log, never mutable tables. New concepts: parking-session, tariff (composable/versioned, FX-ready), shift (manned-only Z-report), capacity-occupancy, validation-discounts, reporting-analytics, clock-integrity, ticket-encoding, anti-passback. New entities: permit, opencv-anpr-service, blocklist. Decisions: session-model, vision-service (host-side ANPR + vehicle verification; scoped AGPL exception for the isolated service). Updates: append-only-event-chain (new event types + vision witness), local-jwt-auth (drop 8h expiry -> until logout; code change pending), lpr-camera (host-side recognition supersedes edge-AI), standing-decisions (AGPL exception), open-questions (+FX, +pay-station money corners, backup). Deferred + flagged: intercom/help-call, receipts/refunds/change, FX engine, lane topology (#1).
1.9 KiB
1.9 KiB
type, tags, sources, updated, status
| type | tags | sources | updated | status | ||||
|---|---|---|---|---|---|---|---|---|
| concept |
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2026-06-15 | open |
Capacity & Occupancy
How many vehicles are inside, how many spaces remain, and what happens when the lot is full.
Occupancy is a projection (like everything else)
occupancy = count(open [[parking-session|sessions]]) — an entry with no matching exit. It is a
fold over the signed append-only-event-chain, never a hand-maintained counter (a counter is
editable and drifts; the chain is the truth). Spaces-free = capacity − occupancy.
capacityis admin-set per site (and per zone/level if the lot has sections — model azoneon capacity + on the entry so multi-level is a later addition, not a rewrite).- Permit concurrency (
maxConcurrent, see permit) is the same kind of fold, scoped to one permit's open sessions.
Full → refuse entry + FULL sign
- When
occupancy ≥ capacity, the entry flow refuses (novehicle_entry, no barrier open) and can drive a "FULL" sign (a relay/output, via the device adapter layer). - Safety/policy nuance: "full" blocks entry only — exit always works (fail-state-safety: exit fails open; never trap a vehicle). Permit holders may be allowed in past a "transient full" threshold (reserve spaces for subscribers) — an optional policy knob.
- Counting drift is real: tailgating (two cars, one entry) and missed reads make the live count diverge from physical reality. The count is the system's occupancy; periodic ground-truth (a loop count, or the opencv-anpr-service count) reconciles it — surfaced as an anomaly, not silently corrected.
Open
- Whether "FULL" is a hard block or a soft warning (operator can wave one in) — operator policy.
- Zone/level granularity at launch vs. single capacity number.
- Reserve-for-permits threshold.