Scaffold Regress: Fastify+SQLite server and Vue frontend for the Ingress-style BTC Map capture game

- Server: NIP-98 nostr auth (session cookies), BTC Map sync, claim/link/field
  routes, physical-presence checks via geolocation distance. 31 tests passing.
- Frontend: Leaflet map, team pick, claim/link UI, Archipelago identity
  bridge vendored (nostr-provider.js) for dashboard launch support.
- Verified end-to-end against the live BTC Map API (167 real Madeira places)
  and via genuine NIP-98-signed HTTP requests against the built app.

server/src/services/fields.ts

@@ -0,0 +1,78 @@
+import type { LatLon } from './geo.js';
+import { triangleAreaKm2 } from './geo.js';
+
+export interface LinkEdge {
+  fromPlaceId: number;
+  toPlaceId: number;
+  team: string;
+}
+
+export interface Field {
+  team: string;
+  placeIds: [number, number, number];
+  areaKm2: number;
+}
+
+/**
+ * Every set of three mutually-linked, same-team places forms a control field —
+ * mirrors Ingress's triangle-fill rule. Recomputed from scratch on read rather
+ * than persisted, since claims/links can invalidate fields from several call
+ * sites and a derived view can't go stale.
+ */
+export function computeFields(links: LinkEdge[], placeCoords: Map<number, LatLon>): Field[] {
+  const adjacencyByTeam = new Map<string, Map<number, Set<number>>>();
+  for (const link of links) {
+    if (!adjacencyByTeam.has(link.team)) adjacencyByTeam.set(link.team, new Map());
+    const adj = adjacencyByTeam.get(link.team)!;
+    if (!adj.has(link.fromPlaceId)) adj.set(link.fromPlaceId, new Set());
+    if (!adj.has(link.toPlaceId)) adj.set(link.toPlaceId, new Set());
+    adj.get(link.fromPlaceId)!.add(link.toPlaceId);
+    adj.get(link.toPlaceId)!.add(link.fromPlaceId);
+  }
+
+  const fields: Field[] = [];
+  for (const [team, adj] of adjacencyByTeam) {
+    const nodes = [...adj.keys()].sort((x, y) => x - y);
+    for (const u of nodes) {
+      const uNeighbors = [...adj.get(u)!].filter((v) => v > u);
+      for (const v of uNeighbors) {
+        const vNeighbors = adj.get(v)!;
+        for (const w of uNeighbors) {
+          if (w <= v || !vNeighbors.has(w)) continue;
+          const a = placeCoords.get(u);
+          const b = placeCoords.get(v);
+          const c = placeCoords.get(w);
+          if (!a || !b || !c) continue;
+          fields.push({ team, placeIds: [u, v, w], areaKm2: triangleAreaKm2(a, b, c) });
+        }
+      }
+    }
+  }
+  return fields;
+}
+
+export interface TeamScore {
+  team: string;
+  claimedPlaces: number;
+  links: number;
+  fields: number;
+  areaKm2: number;
+}
+
+export function summarizeScores(
+  teams: string[],
+  claimCounts: Map<string, number>,
+  linkCounts: Map<string, number>,
+  fields: Field[],
+): TeamScore[] {
+  return teams.map((team) => {
+    const teamFields = fields.filter((f) => f.team === team);
+    return {
+      team,
+      claimedPlaces: claimCounts.get(team) ?? 0,
+      links: linkCounts.get(team) ?? 0,
+      fields: teamFields.length,
+      areaKm2: teamFields.reduce((sum, f) => sum + f.areaKm2, 0),
+    };
+  });
+}