feat: show recognized plate in live feed + active sessions

Surface the advisory ANPR plate (device_events kind="read", keyed by
session identity — unsigned, prunable, never an access decision) next to
entry/exit events in the live feed and on active-session rows.

Resolved at serialize time (new plate-lookup.ts; prefers an entry read;
one device_events scan per page) like subscriber-name enrichment — the
signed ledger is untouched. Adds plate? to the shared LedgerEvent and to
ActiveSession/SessionLookup; a small amber badge in the UI.

Caveat: a vehicle_entry is signed + pushed over WS before the async ANPR
read lands, so a fresh feed row may show no plate until reload; always
present on active sessions.

Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V

apps/server/src/event-enrich.ts

@@ -1,5 +1,6 @@
 import { eq, subscriptions, type Db } from "@parking/db";
 import type { LedgerEvent } from "@parking/shared";
+import { plateForIdentity, platesForIdentities } from "./plate-lookup.js";
 
 // READ-TIME event enrichment. The signed ledger stays minimal and stable; some fields
 // are nice to SHOW but must not be signed (they can change, or depend on other tables).
@@ -45,12 +46,43 @@ export function clearHolderCache(): void {
 }
 
 /**
- * Attach read-time display fields to a raw ledger row before it goes to a client.
- * Currently: `subscriberLabel` for subscription occurrences. Idempotent and cheap;
- * non-subscription events pass through unchanged (no `subscriberLabel`).
+ * Attach read-time display fields to a raw ledger row before it goes to a client:
+ *   - `subscriberLabel` for a subscription occurrence (payload.permitId → holder name);
+ *   - `plate` for an entry/exit event whose session has an advisory ANPR read.
+ * Idempotent and cheap; events without either pass through unchanged. Used by the WS
+ * feed (per event). For the bulk feed page prefer `enrichEvents` (one plate scan).
  */
 export function enrichEvent<T extends LedgerEvent>(db: Db, event: T): T {
+  let out: T = event;
   const permitId = event.payload && typeof event.payload.permitId === "string" ? event.payload.permitId : null;
-  if (!permitId) return event;
-  return { ...event, subscriberLabel: holderName(db, permitId) ?? SUBSCRIBER_FALLBACK };
+  if (permitId) out = { ...out, subscriberLabel: holderName(db, permitId) ?? SUBSCRIBER_FALLBACK };
+  if ((event.type === "vehicle_entry" || event.type === "vehicle_exit") && event.identity) {
+    const p = plateForIdentity(db, event.identity);
+    if (p) out = { ...out, plate: p.plate };
+  }
+  return out;
+}
+
+/**
+ * Bulk variant for the feed page: enriches a list of events with subscriber labels AND
+ * plates using a SINGLE device_events scan for all the plates (instead of one per row).
+ * Order preserved.
+ */
+export function enrichEvents<T extends LedgerEvent>(db: Db, events: T[]): T[] {
+  // Collect identities of entry/exit events to resolve their plates in one scan.
+  const wanted = new Set<string>();
+  for (const e of events) {
+    if ((e.type === "vehicle_entry" || e.type === "vehicle_exit") && e.identity) wanted.add(e.identity);
+  }
+  const plates = wanted.size ? platesForIdentities(db, wanted) : new Map();
+  return events.map((e) => {
+    let out: T = e;
+    const permitId = e.payload && typeof e.payload.permitId === "string" ? e.payload.permitId : null;
+    if (permitId) out = { ...out, subscriberLabel: holderName(db, permitId) ?? SUBSCRIBER_FALLBACK };
+    if ((e.type === "vehicle_entry" || e.type === "vehicle_exit") && e.identity) {
+      const p = plates.get(e.identity);
+      if (p) out = { ...out, plate: p.plate };
+    }
+    return out;
+  });
 }