db: business-layer schema — ledger/device event split, tariffs, permits, sessions

Implements the wiki design in packages/db + packages/shared.

Event split: rename events -> ledger_events (signed business ledger) and add
device_events (unsigned telemetry). ledger_events gains a signed JSON payload
(amount/tariffVersionId/sessionRef/tender…) + keyId; canonicalize() includes
the payload via sorted-key serialization so business data is tamper-evident.
Raw Dingtian input now writes device_events, not a signed input_received.

New tables: tariffs + immutable tariff_versions (composable/versioned, currency
+ FX-ready), permits (+ permit_credentials, permit_plates; maxConcurrent default
1), blocklist, sessions (rebuildable projection cache — not a source of truth).

shared: split ParkingEvent/Type into LedgerEvent/LedgerEventType + DeviceEventKind;
add LedgerPayload, Tender, TariffStructure/TariffBlock.

Regenerated a single baseline migration (no production chain data existed).
Verified: chain appends + verifyChain ok; tampering a payment payload breaks
the signature. Full repo builds (5/5).

apps/server/src/event-log.ts

@@ -1,6 +1,6 @@
 import { createHash, randomUUID } from "node:crypto";
-import { desc, events, type Db, type EventRow } from "@parking/db";
+import { desc, ledgerEvents, type Db, type LedgerEventRow } from "@parking/db";
-import type { Direction, IdentitySource, ParkingEventType, Signer } from "@parking/shared";
+import type { Direction, IdentitySource, LedgerEventType, LedgerPayload, Signer } from "@parking/shared";
 
 // The append-only, hash-chained, signed event log — the system's core anti-fraud
 // primitive (see wiki/concepts/append-only-event-chain.md). Entry/exit and device
@@ -16,11 +16,13 @@ import type { Direction, IdentitySource, ParkingEventType, Signer } from "@parki
 //    so we guard it with an in-process async lock as well.
 
 export interface AppendInput {
-  readonly type: ParkingEventType;
+  readonly type: LedgerEventType;
   readonly lane: number;
   readonly direction?: Direction | null;
   readonly source?: IdentitySource | null;
   readonly identity?: string | null;
+  /** Type-specific business data (amount, tariffVersionId, sessionRef…). Signed. */
+  readonly payload?: LedgerPayload | null;
   /** Event time (ISO-8601). Defaults to now. */
   readonly occurredAt?: string;
 }
@@ -39,6 +41,7 @@ export function canonicalize(e: {
   lane: number;
   source: string | null;
   identity: string | null;
+  payload: Record<string, unknown> | null;
   occurredAt: string;
   prevHash: string | null;
 }): string {
@@ -49,11 +52,33 @@ export function canonicalize(e: {
     e.lane,
     e.source ?? null,
     e.identity ?? null,
+    // Payload is part of the signed form so business data is tamper-evident.
+    // Serialize with sorted keys for byte-stability (object key order must not
+    // change a signature). null when the event type carries no payload.
+    canonicalPayload(e.payload),
     e.occurredAt,
     e.prevHash ?? null,
   ]);
 }
 
+/** Deterministic (key-sorted, recursive) JSON for the payload slot. */
+function canonicalPayload(p: Record<string, unknown> | null | undefined): unknown {
+  if (p == null) return null;
+  const sort = (v: unknown): unknown => {
+    if (Array.isArray(v)) return v.map(sort);
+    if (v && typeof v === "object") {
+      return Object.keys(v as Record<string, unknown>)
+        .sort()
+        .reduce<Record<string, unknown>>((o, k) => {
+          o[k] = sort((v as Record<string, unknown>)[k]);
+          return o;
+        }, {});
+    }
+    return v;
+  };
+  return sort(p);
+}
+
 /** SHA-256 of an event's canonical form (hex) — what the NEXT event chains to. */
 export function hashEvent(canonical: string): string {
   return createHash("sha256").update(canonical, "utf8").digest("hex");
@@ -71,24 +96,25 @@ export class EventLog {
   }
 
   /** Append one event to the chain. Returns the persisted row. Serialized. */
-  append(input: AppendInput): Promise<EventRow> {
+  append(input: AppendInput): Promise<LedgerEventRow> {
     const run = this.#tail.then(() => this.#appendNow(input));
     // Keep the chain going even if one append rejects (don't wedge the lock).
     this.#tail = run.catch(() => undefined);
     return run;
   }
 
-  #appendNow(input: AppendInput): EventRow {
+  #appendNow(input: AppendInput): LedgerEventRow {
     const prev = this.#db
       .select()
-      .from(events)
+      .from(ledgerEvents)
-      .orderBy(desc(events.index))
+      .orderBy(desc(ledgerEvents.index))
       .limit(1)
       .get();
 
     const index = (prev?.index ?? 0) + 1;
     const prevHash = prev ? hashEvent(canonicalize(prev)) : null;
     const occurredAt = input.occurredAt ?? new Date().toISOString();
+    const payload = input.payload ?? null;
 
     const canonical = canonicalize({
       index,
@@ -97,6 +123,7 @@ export class EventLog {
       lane: input.lane,
       source: input.source ?? null,
       identity: input.identity ?? null,
+      payload,
       occurredAt,
       prevHash,
     });
@@ -109,13 +136,15 @@ export class EventLog {
       lane: input.lane,
       source: input.source ?? null,
       identity: input.identity ?? null,
+      payload,
       occurredAt,
       prevHash,
       signature: this.#signer.sign(canonical),
+      keyId: this.#signer.keyId,
     };
 
-    this.#db.insert(events).values(row).run();
+    this.#db.insert(ledgerEvents).values(row).run();
-    return row as EventRow;
+    return row as LedgerEventRow;
   }
 
   /**
@@ -125,7 +154,7 @@ export class EventLog {
    * row (index gap), and a forged/invalid signature.
    */
   verifyChain(): { ok: true } | { ok: false; index: number; reason: string } {
-    const rows = this.#db.select().from(events).orderBy(events.index).all();
+    const rows = this.#db.select().from(ledgerEvents).orderBy(ledgerEvents.index).all();
     let expectedIndex = 1;
     let prevHash: string | null = null;
     for (const row of rows) {

apps/server/src/routes/events.ts

@@ -1,5 +1,5 @@
 import type { FastifyInstance } from "fastify";
-import { desc, events, type Db } from "@parking/db";
+import { desc, ledgerEvents, type Db } from "@parking/db";
 import { requireRole } from "../auth.js";
 import type { EventLog } from "../event-log.js";
 
@@ -22,7 +22,7 @@ export async function eventRoutes(
     { preHandler: guard },
     async (req) => {
       const limit = Math.min(Math.max(Number(req.query.limit) || 100, 1), 1000);
-      const rows = db.select().from(events).orderBy(desc(events.index)).limit(limit).all();
+      const rows = db.select().from(ledgerEvents).orderBy(desc(ledgerEvents.index)).limit(limit).all();
       return { events: rows };
     },
   );

apps/server/src/server.ts

@@ -1,7 +1,8 @@
 import cookie from "@fastify/cookie";
 import jwt from "@fastify/jwt";
 import Fastify, { type FastifyInstance } from "fastify";
-import { createDb, type Db } from "@parking/db";
+import { randomUUID } from "node:crypto";
+import { createDb, deviceEvents as deviceEventsTable, type Db } from "@parking/db";
 import { TOKEN_COOKIE, requireJwtSecret } from "./auth.js";
 import { deviceEvents } from "./device-events.js";
 import { EventLog } from "./event-log.js";
@@ -70,39 +71,41 @@ export async function buildServer(opts: BuildOptions = {}): Promise<FastifyInsta
   app.addHook("onReady", async () => printerMonitor.start());
   app.addHook("onClose", async () => printerMonitor.stop());
 
-  // Append-only signed event log. Subscribe device pushes (e.g. Dingtian button
+  // Append-only signed business LEDGER (ledger_events). Holds only business facts
-  // presses) into the hash-chained, signed `events` table — the anti-fraud audit
+  // (vehicle_entry/exit, payment, void, …) — the anti-fraud audit trail. A raw
-  // trail. The device is NOT trusted; the host record is the source of truth, and
+  // button press is NOT a business fact: it's device telemetry, recorded UNSIGNED
-  // a relay open with no matching signed event is itself the anomaly. We record
+  // in device_events. The entry flow (TODO) turns an input into a signed
-  // the raw input faithfully as `input_received` (not yet a `vehicle_entry` — that
+  // vehicle_entry once a ticket prints + the barrier is commanded.
-  // comes with the full entry flow). See wiki/concepts/append-only-event-chain.md.
+  // See wiki/decisions/event-streams-split.md.
   const eventLog = new EventLog(db, buildSigner(app.log));
   await eventRoutes(app, db, eventLog);
   const unsubscribeInput = deviceEvents.onInput((e) => {
     // Resolve which lane the device belongs to. -1 marks "device fired but isn't
     // mapped to a lane" (assigned without a lane, or a stale id) — still recorded
-    // faithfully (the chain is append-only) rather than silently dropped or
+    // faithfully rather than silently dropped or mis-stamped as lane 0 (a real lane).
-    // mis-stamped as lane 0, which is a real lane.
     const lane = laneMap.laneFor(e.deviceId) ?? -1;
     if (lane === -1) {
       app.log.warn(`input from unmapped device ${e.driverId}:${e.deviceId} — logged as lane -1`);
     }
-    eventLog
+    try {
-      .append({
+      db.insert(deviceEventsTable)
-        type: "input_received",
+        .values({
-        lane,
+          id: randomUUID(),
-        // `source` is an IdentitySource (wiegand/lpr/qr/ticket/manual) — how a
+          deviceId: e.deviceId,
-        // VEHICLE was identified. A raw input has none, so it stays null. The
+          lane,
-        // device provenance lives in `identity` instead.
+          category: "access",
-        source: null,
+          kind: "input",
-        identity: `${e.driverId}:${e.deviceId} input:${e.input}/${e.edge}`,
+          detail: { driverId: e.driverId, input: e.input, edge: e.edge },
-        occurredAt: e.at,
+          occurredAt: e.at,
-      })
+        })
-      .catch((err) => app.log.error(`event-log append failed: ${(err as Error).message}`));
+        .run();
+    } catch (err) {
+      app.log.error(`device-event insert failed: ${(err as Error).message}`);
+    }
   });
   app.addHook("onClose", async () => unsubscribeInput());
 
-  // TODO: entry flow (input event → signed event → print → relay).
+  // TODO: entry flow (device input → signed vehicle_entry → print → relay).
 
   return app;
 }

packages/db/drizzle/0000_absent_rocket_raccoon.sql

@@ -1,23 +0,0 @@
-CREATE TABLE `events` (
-	`id` text PRIMARY KEY NOT NULL,
-	`index` integer NOT NULL,
-	`type` text NOT NULL,
-	`direction` text,
-	`lane` integer NOT NULL,
-	`source` text,
-	`identity` text,
-	`occurred_at` text NOT NULL,
-	`prev_hash` text,
-	`signature` text NOT NULL
-);
---> statement-breakpoint
-CREATE UNIQUE INDEX `events_index_unique` ON `events` (`index`);--> statement-breakpoint
-CREATE TABLE `users` (
-	`id` text PRIMARY KEY NOT NULL,
-	`username` text NOT NULL,
-	`password_hash` text NOT NULL,
-	`role` text NOT NULL,
-	`created_at` text DEFAULT (current_timestamp) NOT NULL
-);
---> statement-breakpoint
-CREATE UNIQUE INDEX `users_username_unique` ON `users` (`username`);

packages/db/drizzle/0000_baseline.sql

@@ -0,0 +1,113 @@
+CREATE TABLE `blocklist` (
+	`id` text PRIMARY KEY NOT NULL,
+	`kind` text NOT NULL,
+	`value` text NOT NULL,
+	`reason` text,
+	`active` integer DEFAULT true NOT NULL,
+	`added_by` text,
+	`added_at` text DEFAULT (current_timestamp) NOT NULL
+);
+--> statement-breakpoint
+CREATE TABLE `device_events` (
+	`id` text PRIMARY KEY NOT NULL,
+	`device_id` text,
+	`lane` integer,
+	`category` text,
+	`kind` text NOT NULL,
+	`detail` text,
+	`occurred_at` text DEFAULT (current_timestamp) NOT NULL
+);
+--> statement-breakpoint
+CREATE TABLE `lane_devices` (
+	`id` text PRIMARY KEY NOT NULL,
+	`lane` integer NOT NULL,
+	`category` text NOT NULL,
+	`driver_id` text NOT NULL,
+	`config` text NOT NULL,
+	`enabled` integer DEFAULT true NOT NULL,
+	`created_at` text DEFAULT (current_timestamp) NOT NULL
+);
+--> statement-breakpoint
+CREATE TABLE `ledger_events` (
+	`id` text PRIMARY KEY NOT NULL,
+	`index` integer NOT NULL,
+	`type` text NOT NULL,
+	`direction` text,
+	`lane` integer NOT NULL,
+	`source` text,
+	`identity` text,
+	`payload` text,
+	`occurred_at` text NOT NULL,
+	`prev_hash` text,
+	`signature` text NOT NULL,
+	`key_id` text NOT NULL
+);
+--> statement-breakpoint
+CREATE UNIQUE INDEX `ledger_events_index_unique` ON `ledger_events` (`index`);--> statement-breakpoint
+CREATE TABLE `permit_credentials` (
+	`id` text PRIMARY KEY NOT NULL,
+	`permit_id` text NOT NULL,
+	`kind` text NOT NULL,
+	`value` text NOT NULL
+);
+--> statement-breakpoint
+CREATE TABLE `permit_plates` (
+	`id` text PRIMARY KEY NOT NULL,
+	`permit_id` text NOT NULL,
+	`plate` text NOT NULL
+);
+--> statement-breakpoint
+CREATE TABLE `permits` (
+	`id` text PRIMARY KEY NOT NULL,
+	`holder_name` text,
+	`contact` text,
+	`max_concurrent` integer DEFAULT 1,
+	`valid_from` text,
+	`valid_to` text,
+	`status` text DEFAULT 'active' NOT NULL,
+	`created_at` text DEFAULT (current_timestamp) NOT NULL
+);
+--> statement-breakpoint
+CREATE TABLE `sessions` (
+	`id` text PRIMARY KEY NOT NULL,
+	`lane` integer,
+	`identity` text,
+	`source` text,
+	`permit_id` text,
+	`entered_at` text NOT NULL,
+	`exited_at` text,
+	`state` text DEFAULT 'open' NOT NULL,
+	`last_event_index` integer
+);
+--> statement-breakpoint
+CREATE TABLE `setup_state` (
+	`id` integer PRIMARY KEY NOT NULL,
+	`completed_at` text
+);
+--> statement-breakpoint
+CREATE TABLE `tariff_versions` (
+	`id` text PRIMARY KEY NOT NULL,
+	`tariff_id` text NOT NULL,
+	`effective_from` text NOT NULL,
+	`currency` text NOT NULL,
+	`structure` text NOT NULL,
+	`created_by` text,
+	`created_at` text DEFAULT (current_timestamp) NOT NULL
+);
+--> statement-breakpoint
+CREATE TABLE `tariffs` (
+	`id` text PRIMARY KEY NOT NULL,
+	`scope` text DEFAULT 'site' NOT NULL,
+	`name` text NOT NULL,
+	`created_at` text DEFAULT (current_timestamp) NOT NULL
+);
+--> statement-breakpoint
+CREATE TABLE `users` (
+	`id` text PRIMARY KEY NOT NULL,
+	`username` text NOT NULL,
+	`password_hash` text NOT NULL,
+	`role` text NOT NULL,
+	`created_at` text DEFAULT (current_timestamp) NOT NULL
+);
+--> statement-breakpoint
+CREATE UNIQUE INDEX `users_username_unique` ON `users` (`username`);

packages/db/drizzle/0001_cuddly_maria_hill.sql

@@ -1,14 +0,0 @@
-CREATE TABLE `lane_devices` (
-	`id` text PRIMARY KEY NOT NULL,
-	`lane` integer NOT NULL,
-	`category` text NOT NULL,
-	`driver_id` text NOT NULL,
-	`config` text NOT NULL,
-	`enabled` integer DEFAULT true NOT NULL,
-	`created_at` text DEFAULT (current_timestamp) NOT NULL
-);
---> statement-breakpoint
-CREATE TABLE `setup_state` (
-	`id` integer PRIMARY KEY NOT NULL,
-	`completed_at` text
-);

packages/db/drizzle/meta/0000_snapshot.json

@@ -1,11 +1,193 @@
 {
   "version": "6",
   "dialect": "sqlite",
-  "id": "721bbb8f-b929-4018-9420-0ae75b03ff93",
+  "id": "cd09c11f-4306-4ac8-a335-7c050d080ab6",
   "prevId": "00000000-0000-0000-0000-000000000000",
   "tables": {
-    "events": {
+    "blocklist": {
-      "name": "events",
+      "name": "blocklist",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "text",
+          "primaryKey": true,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "kind": {
+          "name": "kind",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "value": {
+          "name": "value",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "reason": {
+          "name": "reason",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false,
+          "autoincrement": false
+        },
+        "active": {
+          "name": "active",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false,
+          "default": true
+        },
+        "added_by": {
+          "name": "added_by",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false,
+          "autoincrement": false
+        },
+        "added_at": {
+          "name": "added_at",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false,
+          "default": "(current_timestamp)"
+        }
+      },
+      "indexes": {},
+      "foreignKeys": {},
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {},
+      "checkConstraints": {}
+    },
+    "device_events": {
+      "name": "device_events",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "text",
+          "primaryKey": true,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "device_id": {
+          "name": "device_id",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false,
+          "autoincrement": false
+        },
+        "lane": {
+          "name": "lane",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": false,
+          "autoincrement": false
+        },
+        "category": {
+          "name": "category",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false,
+          "autoincrement": false
+        },
+        "kind": {
+          "name": "kind",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "detail": {
+          "name": "detail",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false,
+          "autoincrement": false
+        },
+        "occurred_at": {
+          "name": "occurred_at",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false,
+          "default": "(current_timestamp)"
+        }
+      },
+      "indexes": {},
+      "foreignKeys": {},
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {},
+      "checkConstraints": {}
+    },
+    "lane_devices": {
+      "name": "lane_devices",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "text",
+          "primaryKey": true,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "lane": {
+          "name": "lane",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "category": {
+          "name": "category",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "driver_id": {
+          "name": "driver_id",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "config": {
+          "name": "config",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "enabled": {
+          "name": "enabled",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false,
+          "default": true
+        },
+        "created_at": {
+          "name": "created_at",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false,
+          "default": "(current_timestamp)"
+        }
+      },
+      "indexes": {},
+      "foreignKeys": {},
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {},
+      "checkConstraints": {}
+    },
+    "ledger_events": {
+      "name": "ledger_events",
       "columns": {
         "id": {
           "name": "id",
@@ -56,6 +238,13 @@
           "notNull": false,
           "autoincrement": false
         },
+        "payload": {
+          "name": "payload",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false,
+          "autoincrement": false
+        },
         "occurred_at": {
           "name": "occurred_at",
           "type": "text",
@@ -76,11 +265,18 @@
           "primaryKey": false,
           "notNull": true,
           "autoincrement": false
+        },
+        "key_id": {
+          "name": "key_id",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
         }
       },
       "indexes": {
-        "events_index_unique": {
+        "ledger_events_index_unique": {
-          "name": "events_index_unique",
+          "name": "ledger_events_index_unique",
           "columns": [
             "index"
           ],
@@ -92,6 +288,342 @@
       "uniqueConstraints": {},
       "checkConstraints": {}
     },
+    "permit_credentials": {
+      "name": "permit_credentials",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "text",
+          "primaryKey": true,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "permit_id": {
+          "name": "permit_id",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "kind": {
+          "name": "kind",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "value": {
+          "name": "value",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        }
+      },
+      "indexes": {},
+      "foreignKeys": {},
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {},
+      "checkConstraints": {}
+    },
+    "permit_plates": {
+      "name": "permit_plates",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "text",
+          "primaryKey": true,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "permit_id": {
+          "name": "permit_id",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "plate": {
+          "name": "plate",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        }
+      },
+      "indexes": {},
+      "foreignKeys": {},
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {},
+      "checkConstraints": {}
+    },
+    "permits": {
+      "name": "permits",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "text",
+          "primaryKey": true,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "holder_name": {
+          "name": "holder_name",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false,
+          "autoincrement": false
+        },
+        "contact": {
+          "name": "contact",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false,
+          "autoincrement": false
+        },
+        "max_concurrent": {
+          "name": "max_concurrent",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": false,
+          "autoincrement": false,
+          "default": 1
+        },
+        "valid_from": {
+          "name": "valid_from",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false,
+          "autoincrement": false
+        },
+        "valid_to": {
+          "name": "valid_to",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false,
+          "autoincrement": false
+        },
+        "status": {
+          "name": "status",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false,
+          "default": "'active'"
+        },
+        "created_at": {
+          "name": "created_at",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false,
+          "default": "(current_timestamp)"
+        }
+      },
+      "indexes": {},
+      "foreignKeys": {},
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {},
+      "checkConstraints": {}
+    },
+    "sessions": {
+      "name": "sessions",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "text",
+          "primaryKey": true,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "lane": {
+          "name": "lane",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": false,
+          "autoincrement": false
+        },
+        "identity": {
+          "name": "identity",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false,
+          "autoincrement": false
+        },
+        "source": {
+          "name": "source",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false,
+          "autoincrement": false
+        },
+        "permit_id": {
+          "name": "permit_id",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false,
+          "autoincrement": false
+        },
+        "entered_at": {
+          "name": "entered_at",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "exited_at": {
+          "name": "exited_at",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false,
+          "autoincrement": false
+        },
+        "state": {
+          "name": "state",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false,
+          "default": "'open'"
+        },
+        "last_event_index": {
+          "name": "last_event_index",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": false,
+          "autoincrement": false
+        }
+      },
+      "indexes": {},
+      "foreignKeys": {},
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {},
+      "checkConstraints": {}
+    },
+    "setup_state": {
+      "name": "setup_state",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "integer",
+          "primaryKey": true,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "completed_at": {
+          "name": "completed_at",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false,
+          "autoincrement": false
+        }
+      },
+      "indexes": {},
+      "foreignKeys": {},
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {},
+      "checkConstraints": {}
+    },
+    "tariff_versions": {
+      "name": "tariff_versions",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "text",
+          "primaryKey": true,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "tariff_id": {
+          "name": "tariff_id",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "effective_from": {
+          "name": "effective_from",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "currency": {
+          "name": "currency",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "structure": {
+          "name": "structure",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "created_by": {
+          "name": "created_by",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false,
+          "autoincrement": false
+        },
+        "created_at": {
+          "name": "created_at",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false,
+          "default": "(current_timestamp)"
+        }
+      },
+      "indexes": {},
+      "foreignKeys": {},
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {},
+      "checkConstraints": {}
+    },
+    "tariffs": {
+      "name": "tariffs",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "text",
+          "primaryKey": true,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "scope": {
+          "name": "scope",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false,
+          "default": "'site'"
+        },
+        "name": {
+          "name": "name",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "created_at": {
+          "name": "created_at",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false,
+          "default": "(current_timestamp)"
+        }
+      },
+      "indexes": {},
+      "foreignKeys": {},
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {},
+      "checkConstraints": {}
+    },
     "users": {
       "name": "users",
       "columns": {

packages/db/drizzle/meta/0001_snapshot.json

@@ -1,245 +0,0 @@
-{
-  "version": "6",
-  "dialect": "sqlite",
-  "id": "1073123c-0df9-4109-84bf-7f23b95ec5bd",
-  "prevId": "721bbb8f-b929-4018-9420-0ae75b03ff93",
-  "tables": {
-    "events": {
-      "name": "events",
-      "columns": {
-        "id": {
-          "name": "id",
-          "type": "text",
-          "primaryKey": true,
-          "notNull": true,
-          "autoincrement": false
-        },
-        "index": {
-          "name": "index",
-          "type": "integer",
-          "primaryKey": false,
-          "notNull": true,
-          "autoincrement": false
-        },
-        "type": {
-          "name": "type",
-          "type": "text",
-          "primaryKey": false,
-          "notNull": true,
-          "autoincrement": false
-        },
-        "direction": {
-          "name": "direction",
-          "type": "text",
-          "primaryKey": false,
-          "notNull": false,
-          "autoincrement": false
-        },
-        "lane": {
-          "name": "lane",
-          "type": "integer",
-          "primaryKey": false,
-          "notNull": true,
-          "autoincrement": false
-        },
-        "source": {
-          "name": "source",
-          "type": "text",
-          "primaryKey": false,
-          "notNull": false,
-          "autoincrement": false
-        },
-        "identity": {
-          "name": "identity",
-          "type": "text",
-          "primaryKey": false,
-          "notNull": false,
-          "autoincrement": false
-        },
-        "occurred_at": {
-          "name": "occurred_at",
-          "type": "text",
-          "primaryKey": false,
-          "notNull": true,
-          "autoincrement": false
-        },
-        "prev_hash": {
-          "name": "prev_hash",
-          "type": "text",
-          "primaryKey": false,
-          "notNull": false,
-          "autoincrement": false
-        },
-        "signature": {
-          "name": "signature",
-          "type": "text",
-          "primaryKey": false,
-          "notNull": true,
-          "autoincrement": false
-        }
-      },
-      "indexes": {
-        "events_index_unique": {
-          "name": "events_index_unique",
-          "columns": [
-            "index"
-          ],
-          "isUnique": true
-        }
-      },
-      "foreignKeys": {},
-      "compositePrimaryKeys": {},
-      "uniqueConstraints": {},
-      "checkConstraints": {}
-    },
-    "lane_devices": {
-      "name": "lane_devices",
-      "columns": {
-        "id": {
-          "name": "id",
-          "type": "text",
-          "primaryKey": true,
-          "notNull": true,
-          "autoincrement": false
-        },
-        "lane": {
-          "name": "lane",
-          "type": "integer",
-          "primaryKey": false,
-          "notNull": true,
-          "autoincrement": false
-        },
-        "category": {
-          "name": "category",
-          "type": "text",
-          "primaryKey": false,
-          "notNull": true,
-          "autoincrement": false
-        },
-        "driver_id": {
-          "name": "driver_id",
-          "type": "text",
-          "primaryKey": false,
-          "notNull": true,
-          "autoincrement": false
-        },
-        "config": {
-          "name": "config",
-          "type": "text",
-          "primaryKey": false,
-          "notNull": true,
-          "autoincrement": false
-        },
-        "enabled": {
-          "name": "enabled",
-          "type": "integer",
-          "primaryKey": false,
-          "notNull": true,
-          "autoincrement": false,
-          "default": true
-        },
-        "created_at": {
-          "name": "created_at",
-          "type": "text",
-          "primaryKey": false,
-          "notNull": true,
-          "autoincrement": false,
-          "default": "(current_timestamp)"
-        }
-      },
-      "indexes": {},
-      "foreignKeys": {},
-      "compositePrimaryKeys": {},
-      "uniqueConstraints": {},
-      "checkConstraints": {}
-    },
-    "setup_state": {
-      "name": "setup_state",
-      "columns": {
-        "id": {
-          "name": "id",
-          "type": "integer",
-          "primaryKey": true,
-          "notNull": true,
-          "autoincrement": false
-        },
-        "completed_at": {
-          "name": "completed_at",
-          "type": "text",
-          "primaryKey": false,
-          "notNull": false,
-          "autoincrement": false
-        }
-      },
-      "indexes": {},
-      "foreignKeys": {},
-      "compositePrimaryKeys": {},
-      "uniqueConstraints": {},
-      "checkConstraints": {}
-    },
-    "users": {
-      "name": "users",
-      "columns": {
-        "id": {
-          "name": "id",
-          "type": "text",
-          "primaryKey": true,
-          "notNull": true,
-          "autoincrement": false
-        },
-        "username": {
-          "name": "username",
-          "type": "text",
-          "primaryKey": false,
-          "notNull": true,
-          "autoincrement": false
-        },
-        "password_hash": {
-          "name": "password_hash",
-          "type": "text",
-          "primaryKey": false,
-          "notNull": true,
-          "autoincrement": false
-        },
-        "role": {
-          "name": "role",
-          "type": "text",
-          "primaryKey": false,
-          "notNull": true,
-          "autoincrement": false
-        },
-        "created_at": {
-          "name": "created_at",
-          "type": "text",
-          "primaryKey": false,
-          "notNull": true,
-          "autoincrement": false,
-          "default": "(current_timestamp)"
-        }
-      },
-      "indexes": {
-        "users_username_unique": {
-          "name": "users_username_unique",
-          "columns": [
-            "username"
-          ],
-          "isUnique": true
-        }
-      },
-      "foreignKeys": {},
-      "compositePrimaryKeys": {},
-      "uniqueConstraints": {},
-      "checkConstraints": {}
-    }
-  },
-  "views": {},
-  "enums": {},
-  "_meta": {
-    "schemas": {},
-    "tables": {},
-    "columns": {}
-  },
-  "internal": {
-    "indexes": {}
-  }
-}

packages/db/drizzle/meta/_journal.json

@@ -5,15 +5,8 @@
     {
       "idx": 0,
       "version": "6",
-      "when": 1781389618205,
+      "when": 1781539958008,
-      "tag": "0000_absent_rocket_raccoon",
+      "tag": "0000_baseline",
-      "breakpoints": true
-    },
-    {
-      "idx": 1,
-      "version": "6",
-      "when": 1781416636098,
-      "tag": "0001_cuddly_maria_hill",
       "breakpoints": true
     }
   ]

packages/db/src/schema.ts

@@ -2,10 +2,16 @@ import { sql } from "drizzle-orm";
 import { integer, sqliteTable, text } from "drizzle-orm/sqlite-core";
 
 // Schema notes:
-// - `events` is APPEND-ONLY. Never expose UPDATE/DELETE on it. A correction or
+// - TWO event streams, deliberately separate (see wiki/decisions/event-streams-split.md):
-//   void is a new row of type 'void'. Each row chains to the previous via
+//     • `ledger_events` — the APPEND-ONLY, hash-chained, ATECC608-SIGNED business ledger.
-//   `prevHash` and is signed by the ATECC608 (`signature`). This is the core
+//       Never UPDATE/DELETE. A correction or void is a new row of type 'void'. Each row
-//   anti-fraud integrity mechanism. See wiki/concepts/append-only-event-chain.md.
+//       chains via `prevHash` and is signed (`signature`). The anti-fraud record; sessions,
+//       tariffs and occupancy are PROJECTIONS over it. See append-only-event-chain.md.
+//     • `device_events` — UNSIGNED operational telemetry (relay/printer/camera/reader/input).
+//       High-volume, prunable, never reconciled. See wiki/concepts/device-events.md.
+// - Business master data (tariffs/permits/blocklist) IS mutable, but its USE is fixed in a
+//   signed ledger event, so the audit trail stays append-only. Tariffs are versioned:
+//   editing publishes a new immutable tariff_version. See wiki/concepts/tariff.md.
 // - `users` holds bcrypt hashes + a role; auth is fully local (offline-first).
 //   See wiki/entities/local-jwt-auth.md.
 
@@ -21,7 +27,13 @@ export const users = sqliteTable("users", {
     .default(sql`(current_timestamp)`),
 });
 
-export const events = sqliteTable("events", {
+// --- The signed business ledger (formerly `events`) ----------------------
+// Holds ONLY business/accountability facts: vehicle_entry, vehicle_exit, payment,
+// void, shift_z_report, plus witness-grade barrier_open_command/observed, anomaly.
+// `payload` carries type-specific data (amount, tariffVersionId, sessionRef, tender,
+// plate confidence…) and is part of the SIGNED canonical form, so it is tamper-evident
+// like the rest of the row. See packages/shared ParkingEventType + LedgerPayload.
+export const ledgerEvents = sqliteTable("ledger_events", {
   id: text("id").primaryKey(),
   // Monotonic chain index. Gaps are alarms (see event-log-ingestion).
   index: integer("index").notNull().unique(),
@@ -30,18 +42,43 @@ export const events = sqliteTable("events", {
   lane: integer("lane").notNull(),
   source: text("source"),
   identity: text("identity"),
+  // Type-specific business payload (JSON). Signed as part of the canonical form.
+  payload: text("payload", { mode: "json" }).$type<Record<string, unknown>>(),
   occurredAt: text("occurred_at").notNull(),
   // Hash of the previous event (hex). Null only for the genesis event.
   prevHash: text("prev_hash"),
   // ATECC608 signature over the canonical event payload (hex).
   signature: text("signature").notNull(),
+  // Which signer/key produced `signature` (e.g. "sw-hmac-v1", "atecc608-slot0"),
+  // so old events stay verifiable across a signer swap. See packages/shared Signer.
+  keyId: text("key_id").notNull(),
 });
 
-// Per-lane device assignments chosen by the admin during first-run setup.
+// --- Device telemetry (unsigned, prunable) -------------------------------
+// Operational monitoring, NOT anti-fraud: relay fired, printer paper-out, camera
+// offline, reader read, raw input edges. Keyed to a lane_devices instance; lane is
+// resolved via the LaneMap. No prevHash/signature — this stream may rotate/prune.
+export const deviceEvents = sqliteTable("device_events", {
+  id: text("id").primaryKey(),
+  // The lane_devices instance that produced it (raw provenance).
+  deviceId: text("device_id"),
+  lane: integer("lane"),
+  category: text("category", {
+    enum: ["access", "reader", "camera", "printer"],
+  }),
+  // e.g. "input", "relay", "status", "read", "snapshot".
+  kind: text("kind").notNull(),
+  // Free-form telemetry detail (input number + edge, status flags, error…).
+  detail: text("detail", { mode: "json" }).$type<Record<string, unknown>>(),
+  occurredAt: text("occurred_at")
+    .notNull()
+    .default(sql`(current_timestamp)`),
+});
+
+// --- Per-lane device assignments (first-run setup) -----------------------
 // One row per (lane, category, instance). `driverId` references a driver in the
-// @parking/devices registry; `config` is that driver's JSON config (host, port,
+// @parking/devices registry; `config` is that driver's JSON config. Keeps the
-// credentials…). Lets the system stay device-agnostic and admin-configurable.
+// system device-agnostic + admin-configurable. See device-registry.md, first-run-setup.md.
-// See wiki/concepts/device-registry.md and first-run-setup.md.
 export const laneDevices = sqliteTable("lane_devices", {
   id: text("id").primaryKey(),
   lane: integer("lane").notNull(),
@@ -64,7 +101,124 @@ export const setupState = sqliteTable("setup_state", {
   completedAt: text("completed_at"),
 });
 
+// --- Tariffs (composable, versioned) -------------------------------------
+// A `tariffs` row is a logical rate card; its pricing lives in immutable, effective-
+// dated `tariff_versions`. Editing prices PUBLISHES a new version, never mutates one.
+// A session reprices against the version in force at its entry time; the `payment`
+// ledger event records the tariffVersionId used. "One active tariff per site" today;
+// `scope` lets multiple be added later without migration. See wiki/concepts/tariff.md.
+export const tariffs = sqliteTable("tariffs", {
+  id: text("id").primaryKey(),
+  // Only "site" used now; "lane"/"zone" reserved for multi-tariff later.
+  scope: text("scope", { enum: ["site", "lane", "zone"] }).notNull().default("site"),
+  name: text("name").notNull(),
+  createdAt: text("created_at")
+    .notNull()
+    .default(sql`(current_timestamp)`),
+});
+
+export const tariffVersions = sqliteTable("tariff_versions", {
+  id: text("id").primaryKey(),
+  tariffId: text("tariff_id").notNull(),
+  // The version is in force from this instant (latest with effectiveFrom ≤ entry wins).
+  effectiveFrom: text("effective_from").notNull(),
+  // ISO 4217; selectable. Money everywhere is { minorUnits, currency }, never a float.
+  currency: text("currency").notNull(),
+  // The composable rate card (stepped blocks + caps/grace). Shape: TariffStructure
+  // in packages/shared. Immutable once published.
+  structure: text("structure", { mode: "json" }).notNull().$type<Record<string, unknown>>(),
+  createdBy: text("created_by"),
+  createdAt: text("created_at")
+    .notNull()
+    .default(sql`(current_timestamp)`),
+});
+
+// --- Permits (subscriptions) ---------------------------------------------
+// Mutable master data; every USE produces a signed vehicle_entry/exit ledger event.
+// Two optional, independent bindings: car-count (maxConcurrent, default 1, null =
+// unbound) and plate (plates rows, default none = any car). Identity = card/QR OR a
+// matching plate. Credentials and cars are child rows. See wiki/entities/permit.md.
+export const permits = sqliteTable("permits", {
+  id: text("id").primaryKey(),
+  holderName: text("holder_name"),
+  contact: text("contact"),
+  // Car-count binding: how many of the permit's cars may be inside at once.
+  // null = unbound. Default 1.
+  maxConcurrent: integer("max_concurrent").default(1),
+  validFrom: text("valid_from"),
+  validTo: text("valid_to"),
+  status: text("status", { enum: ["active", "suspended", "revoked"] })
+    .notNull()
+    .default("active"),
+  createdAt: text("created_at")
+    .notNull()
+    .default(sql`(current_timestamp)`),
+});
+
+// A permit's credentials (RF tag/chip/card, or QR). Either opens the lane.
+export const permitCredentials = sqliteTable("permit_credentials", {
+  id: text("id").primaryKey(),
+  permitId: text("permit_id").notNull(),
+  kind: text("kind", { enum: ["rf", "qr"] }).notNull(),
+  value: text("value").notNull(),
+});
+
+// Plate binding (optional). When a permit has plate rows, a matching plate read is
+// itself an accepted identity (card/QR OR plate). Empty = not plate-bound (any car).
+export const permitPlates = sqliteTable("permit_plates", {
+  id: text("id").primaryKey(),
+  permitId: text("permit_id").notNull(),
+  plate: text("plate").notNull(),
+});
+
+// --- Blocklist (banlist) -------------------------------------------------
+// Plates/cards refused at ENTRY (never at exit — never trap a vehicle). A hit appends
+// a signed anomaly/refused-entry ledger event. See wiki/entities/blocklist.md.
+export const blocklist = sqliteTable("blocklist", {
+  id: text("id").primaryKey(),
+  kind: text("kind", { enum: ["plate", "card", "qr"] }).notNull(),
+  value: text("value").notNull(),
+  reason: text("reason"),
+  active: integer("active", { mode: "boolean" }).notNull().default(true),
+  addedBy: text("added_by"),
+  addedAt: text("added_at")
+    .notNull()
+    .default(sql`(current_timestamp)`),
+});
+
+// --- Sessions (PROJECTION cache) -----------------------------------------
+// NOT a source of truth — a rebuildable fold over ledger_events for fast queries
+// (occupancy, pay-station lookup, anti-passback, plate search). Always reconstructable
+// from the signed chain; never the authority for "paid". See wiki/concepts/parking-session.md.
+export const sessions = sqliteTable("sessions", {
+  // The session key = the entry's identity (ticket id or plate).
+  id: text("id").primaryKey(),
+  lane: integer("lane"),
+  // Identity that opened the session, and how it was read.
+  identity: text("identity"),
+  source: text("source"),
+  // null while transient; set when matched to a permit.
+  permitId: text("permit_id"),
+  enteredAt: text("entered_at").notNull(),
+  // null until exit; presence = CLOSED.
+  exitedAt: text("exited_at"),
+  // Derived state for quick filtering: open | paid | closed | voided.
+  state: text("state", { enum: ["open", "paid", "closed", "voided"] })
+    .notNull()
+    .default("open"),
+  // Index of the last ledger event folded into this row (cache freshness / rebuild).
+  lastEventIndex: integer("last_event_index"),
+});
+
 export type UserRow = typeof users.$inferSelect;
-export type EventRow = typeof events.$inferSelect;
+export type LedgerEventRow = typeof ledgerEvents.$inferSelect;
+export type DeviceEventRow = typeof deviceEvents.$inferSelect;
 export type LaneDeviceRow = typeof laneDevices.$inferSelect;
 export type SetupStateRow = typeof setupState.$inferSelect;
+export type TariffRow = typeof tariffs.$inferSelect;
+export type TariffVersionRow = typeof tariffVersions.$inferSelect;
+export type PermitRow = typeof permits.$inferSelect;
+export type PermitCredentialRow = typeof permitCredentials.$inferSelect;
+export type PermitPlateRow = typeof permitPlates.$inferSelect;
+export type BlocklistRow = typeof blocklist.$inferSelect;
+export type SessionRow = typeof sessions.$inferSelect;

packages/shared/src/index.ts

@@ -13,39 +13,106 @@ export type Direction = "entry" | "exit";
 export type IdentitySource = "wiegand" | "lpr" | "qr" | "ticket" | "manual";
 
 /**
- * An append-only parking event. Records are never mutated; corrections are new
+ * A signed business-LEDGER event. Records are never mutated; corrections are new
  * events. `prevHash` chains each event to the previous one; `signature` is the
- * ATECC608 signature over the event contents. See wiki/append-only-event-chain.
+ * ATECC608 signature over the canonical contents (which INCLUDE `payload`).
+ * Distinct from device telemetry — see wiki/decisions/event-streams-split.md.
  */
-export interface ParkingEvent {
+export interface LedgerEvent {
   readonly id: string;
   readonly index: number;
-  readonly type: ParkingEventType;
+  readonly type: LedgerEventType;
   readonly direction: Direction | null;
   readonly lane: number;
   readonly source: IdentitySource | null;
   /** Card number, plate, ticket id, etc. — depends on `source`. */
   readonly identity: string | null;
+  /** Type-specific business data (amount, tariffVersionId, sessionRef…). Signed. */
+  readonly payload: LedgerPayload | null;
   readonly occurredAt: string; // ISO-8601
   /** Hash of the previous event in the chain (hex). Null only for genesis. */
   readonly prevHash: string | null;
   /** ATECC608 signature over the canonical event payload (hex). */
   readonly signature: string;
+  /** Which signer/key produced `signature` (verifiable across a signer swap). */
+  readonly keyId: string;
 }
 
-export type ParkingEventType =
+/** Business/accountability events that live in the SIGNED, hash-chained ledger. */
-  // A raw device input (e.g. a Dingtian button press) was received and recorded.
+export type LedgerEventType =
-  // NOT a confirmed entry — the richer `vehicle_entry` is appended later by the
-  // entry flow once a ticket prints and the barrier is commanded.
-  | "input_received"
   | "vehicle_entry"
   | "vehicle_exit"
+  | "payment"
   | "void"
+  // Witness-grade: a host-commanded open, and an independently-observed open
+  // (loop/sensor) — reconciled against each other.
   | "barrier_open_command"
   | "barrier_open_observed"
   | "shift_z_report"
   | "anomaly";
 
+/** How money was tendered (for payment events + the shift Z-report). */
+export type Tender = "cash" | "card";
+
+/**
+ * Type-specific data carried on a ledger event's `payload`. All amounts are
+ * integer minor units in the named currency — never floats. Fields are optional
+ * because they're event-type-specific; the producer fills what applies.
+ */
+export interface LedgerPayload {
+  /** The parking_session this event concerns (entry/exit/payment/void). */
+  readonly sessionRef?: string;
+  /** payment: amount in minor units, its currency, and how it was tendered. */
+  readonly amountMinor?: number;
+  readonly currency?: string;
+  readonly tender?: Tender;
+  /** payment: which tariff_version priced it (reproducible repricing). */
+  readonly tariffVersionId?: string;
+  /** payment: gross/discount/net split when a validation applied. */
+  readonly grossMinor?: number;
+  readonly discountMinor?: number;
+  /** FX-ready, deferred: rate applied (null/absent now). See open-questions #8. */
+  readonly fxRate?: number | null;
+  /** void / anomaly / override: a human/machine reason code. */
+  readonly reason?: string;
+  /** plate/vehicle from the vision service (advisory). */
+  readonly plate?: string;
+  readonly plateConfidence?: number;
+  /** Free-form for forward-compat without a schema change. */
+  readonly [k: string]: unknown;
+}
+
+/** Operational device telemetry — UNSIGNED, prunable. NOT the ledger. */
+export type DeviceEventKind = "input" | "relay" | "status" | "read" | "snapshot";
+
+/**
+ * The composable rate card stored in a tariff_version.structure. Pure data the
+ * fee function interprets — no rates in code. Stepped duration blocks + caps/grace;
+ * a flat rate is just one block. See wiki/concepts/tariff.md.
+ */
+export interface TariffStructure {
+  /** Free if exited within this (drop-off/turnaround). */
+  readonly gracePeriodEntryMin: number;
+  /** Billing granularity; partial increments round UP. */
+  readonly incrementMin: number;
+  /** Consumed in order as duration accrues; last block may be open-ended. */
+  readonly blocks: readonly TariffBlock[];
+  /** Cap per rolling 24h (null = no cap). */
+  readonly dailyCapMinor: number | null;
+  /** Flat charge when there's no entry id (admin may override at the moment). */
+  readonly lostTicketMinor: number;
+  /** Pay-on-foot walk-back window: minutes after payment to reach the car. */
+  readonly gracePeriodExitMin: number;
+  /** How an overstay top-up is charged. "reprice" = recompute(entry→now) − paid. */
+  readonly overstay: "reprice";
+}
+
+export interface TariffBlock {
+  /** Upper bound of this block in minutes; null = open-ended (thereafter). */
+  readonly uptoMin: number | null;
+  readonly priceMinorPerIncrement: number;
+}
+
 export const ROLES: readonly Role[] = [
   "admin",
   "operator",