Add 500km link cap, block-height-based claim expiry, and link count in score

- MAX_LINK_DISTANCE_KM (default 500): flat cap on link length. Real
  Ingress scales this off portal/resonator level (up to ~655km); Regress
  has no leveling system to scale off of, so this is a single ceiling.
- PORTAL_TIMEOUT_BLOCKS (default 2100): claims stamp the current Bitcoin
  block height (claimed_at_block, new migration) and expire back to
  neutral after this many blocks — the game's clock is block height, not
  wall-clock. Current height comes from mempool.space (BlockHeightService,
  60s cache), same trust model as the BTC Map dependency. A background
  sweep actively reverts timed-out claims (tearing down their links, same
  as a normal recapture); claim/link routes also check inline so
  correctness doesn't depend on sweep timing between runs.
- Pre-existing claims (already live in production) get backfilled with
  the real current block height once at startup rather than a guessed
  historical value — dry-run verified against an actual copy of the live
  production database before deploying.
- Score now reports link count per team alongside places/fields/area
  (backend already computed this; only the frontend display was missing).

22 new tests (53 total): pure expiry-logic unit tests plus full
claim/link/sweep integration tests using a network-free fake block-height
provider (BlockHeightProvider interface + FakeBlockHeight test double).

server/src/app.test.ts

@@ -6,6 +6,7 @@ import { finalizeEvent, generateSecretKey, getPublicKey } from 'nostr-tools/pure
 import type { FastifyInstance } from 'fastify';
 import { buildApp } from './app.js';
 import { loadConfig } from './config.js';
+import { FakeBlockHeight } from './testUtils/fakeBlockHeight.js';
 
 // Three real Madeira BTC Map places, close enough together to link/field in tests.
 const PLACE_A = { id: 1128, lat: 32.6489863, lon: -16.9101835, name: 'Maia' };
@@ -24,6 +25,7 @@ let app: FastifyInstance;
 let dataDir: string;
 let cookieA: string;
 let cookieB: string;
+let fakeBlockHeight: FakeBlockHeight;
 
 function nip98Header(sk: Uint8Array, url: string, method: string): string {
   const event = finalizeEvent(
@@ -51,7 +53,8 @@ async function login(sk: Uint8Array): Promise<string> {
 beforeAll(async () => {
   dataDir = mkdtempSync(join(tmpdir(), 'regress-test-'));
   const config = loadConfig({ DATA_DIR: dataDir, PUBLIC_URL: 'http://localhost:8096' } as NodeJS.ProcessEnv);
-  app = await buildApp({ config, dbPath: ':memory:', logger: false });
+  fakeBlockHeight = new FakeBlockHeight(900_000);
+  app = await buildApp({ config, dbPath: ':memory:', logger: false, blockHeight: fakeBlockHeight });
 
   // Seed places directly rather than hitting the real BTC Map API in tests.
   for (const p of [PLACE_A, PLACE_B, PLACE_C]) {
@@ -273,3 +276,103 @@ describe('link crossing', () => {
     expect(res.statusCode).toBe(200);
   });
 });
+
+describe('max link distance', () => {
+  // 10 degrees of longitude at the equator is ~1,110km — comfortably over
+  // the 500km default cap, and far enough apart that haversineMeters leaves
+  // no ambiguity about which side of the limit this lands on.
+  const FAR_1 = { id: 90101, lat: 0, lon: 0 };
+  const FAR_2 = { id: 90102, lat: 0, lon: 10 };
+
+  beforeAll(async () => {
+    for (const p of [FAR_1, FAR_2]) {
+      app.ctx.db
+        .prepare('INSERT INTO places (id, lat, lon, name, synced_at) VALUES (?, ?, ?, ?, ?)')
+        .run(p.id, p.lat, p.lon, `far-${p.id}`, Math.floor(Date.now() / 1000));
+      await app.inject({
+        method: 'POST',
+        url: `/api/places/${p.id}/claim`,
+        headers: { cookie: cookieA },
+        payload: { lat: p.lat, lon: p.lon },
+      });
+    }
+  });
+
+  it('rejects a link longer than MAX_LINK_DISTANCE_KM', async () => {
+    const res = await app.inject({
+      method: 'POST',
+      url: '/api/links',
+      headers: { cookie: cookieA },
+      payload: { fromPlaceId: FAR_1.id, toPlaceId: FAR_2.id, lat: FAR_1.lat, lon: FAR_1.lon },
+    });
+    expect(res.statusCode).toBe(403);
+    expect(res.json().error).toMatch(/too long/);
+  });
+});
+
+describe('claim expiry (block-height based)', () => {
+  const TIMEOUT_PLACE = { id: 90201, lat: 1, lon: 1, name: 'timeout-test' };
+
+  beforeAll(async () => {
+    app.ctx.db
+      .prepare('INSERT INTO places (id, lat, lon, name, synced_at) VALUES (?, ?, ?, ?, ?)')
+      .run(TIMEOUT_PLACE.id, TIMEOUT_PLACE.lat, TIMEOUT_PLACE.lon, TIMEOUT_PLACE.name, Math.floor(Date.now() / 1000));
+  });
+
+  it('claims and stamps the current block height', async () => {
+    fakeBlockHeight.height = 950_000;
+    const res = await app.inject({
+      method: 'POST',
+      url: `/api/places/${TIMEOUT_PLACE.id}/claim`,
+      headers: { cookie: cookieA },
+      payload: { lat: TIMEOUT_PLACE.lat, lon: TIMEOUT_PLACE.lon },
+    });
+    expect(res.statusCode).toBe(200);
+    expect(res.json().claimedAtBlock).toBe(950_000);
+  });
+
+  it('lets the same team re-claim once the portal has timed out (409 while live, 200 once expired)', async () => {
+    // Before timeout: orange re-claiming orange's own still-live claim is a 409
+    // (this is the case that specifically distinguishes "expired" from "live" —
+    // recapture-by-the-enemy already works regardless of timeout and is covered
+    // by the earlier "lets the rival team capture it" test).
+    fakeBlockHeight.height = 950_000 + 2099; // one block short of expiry
+    const stillLive = await app.inject({
+      method: 'POST',
+      url: `/api/places/${TIMEOUT_PLACE.id}/claim`,
+      headers: { cookie: cookieA },
+      payload: { lat: TIMEOUT_PLACE.lat, lon: TIMEOUT_PLACE.lon },
+    });
+    expect(stillLive.statusCode).toBe(409);
+
+    // Advance past the timeout (claimed at 950_000+2099, timeout is 2100 blocks).
+    fakeBlockHeight.height = 950_000 + 2099 + 2100;
+    const afterTimeout = await app.inject({
+      method: 'POST',
+      url: `/api/places/${TIMEOUT_PLACE.id}/claim`,
+      headers: { cookie: cookieA },
+      payload: { lat: TIMEOUT_PLACE.lat, lon: TIMEOUT_PLACE.lon },
+    });
+    expect(afterTimeout.statusCode).toBe(200); // no longer a 409 — the old claim had decayed to neutral
+  });
+
+  it('background sweep actually deletes expired claims and their links', async () => {
+    const { sweepExpiredClaims } = await import('./services/expiry.js');
+    fakeBlockHeight.height = 960_000;
+    await app.inject({
+      method: 'POST',
+      url: `/api/places/${TIMEOUT_PLACE.id}/claim`,
+      headers: { cookie: cookieA },
+      payload: { lat: TIMEOUT_PLACE.lat, lon: TIMEOUT_PLACE.lon },
+    });
+
+    let claim = app.ctx.db.prepare('SELECT * FROM claims WHERE place_id = ?').get(TIMEOUT_PLACE.id);
+    expect(claim).toBeDefined();
+
+    const swept = sweepExpiredClaims(app.ctx.db, 960_000 + 2100, 2100);
+    expect(swept.map((c) => c.placeId)).toContain(TIMEOUT_PLACE.id);
+
+    claim = app.ctx.db.prepare('SELECT * FROM claims WHERE place_id = ?').get(TIMEOUT_PLACE.id);
+    expect(claim).toBeUndefined();
+  });
+});

server/src/app.ts

@@ -6,6 +6,7 @@ import { existsSync } from 'node:fs';
 import { join } from 'node:path';
 import type { Config } from './config.js';
 import { openDatabase, type DB } from './db/database.js';
+import { BlockHeightService, type BlockHeightProvider } from './services/blockHeight.js';
 import nostrAuth from './plugins/nostr-auth.js';
 import authRoutes from './routes/auth.js';
 import placesRoutes from './routes/places.js';
@@ -17,6 +18,7 @@ import syncRoutes from './routes/sync.js';
 export interface AppContext {
   config: Config;
   db: DB;
+  blockHeight: BlockHeightProvider;
 }
 
 declare module 'fastify' {
@@ -29,6 +31,7 @@ export interface BuildAppOptions {
   config: Config;
   dbPath?: string; // override for tests (':memory:')
   logger?: boolean;
+  blockHeight?: BlockHeightProvider; // override for tests — avoids real network calls
 }
 
 export async function buildApp(opts: BuildAppOptions): Promise<FastifyInstance> {
@@ -37,7 +40,11 @@ export async function buildApp(opts: BuildAppOptions): Promise<FastifyInstance>
 
   const app = Fastify({ logger: opts.logger ?? true, bodyLimit: 1 * 1024 * 1024 });
 
-  const ctx: AppContext = { config, db };
+  const ctx: AppContext = {
+    config,
+    db,
+    blockHeight: opts.blockHeight ?? new BlockHeightService(config.BLOCK_HEIGHT_API_URL),
+  };
   app.decorate('ctx', ctx);
 
   await app.register(cookie);

server/src/config.ts

@@ -21,6 +21,17 @@ const envSchema = z.object({
   BTCMAP_RADIUS_KM: z.coerce.number().default(45),
   // How close (in meters) a player must be to a place to claim it or link from it.
   CLAIM_RADIUS_METERS: z.coerce.number().default(40),
+  // Maximum link length, in kilometers — mirrors Ingress's level-scaled link
+  // range (up to ~655km at max level) with a single flat cap instead, since
+  // Regress has no resonator-leveling system to scale it off of.
+  MAX_LINK_DISTANCE_KM: z.coerce.number().default(500),
+  // Claims expire after this many Bitcoin blocks and revert to neutral —
+  // mirrors Ingress's real-world portal decay, but block-height-based
+  // instead of wall-clock, since that's the native "clock" for this game.
+  PORTAL_TIMEOUT_BLOCKS: z.coerce.number().default(2100),
+  BLOCK_HEIGHT_API_URL: z.string().url().default('https://mempool.space/api/blocks/tip/height'),
+  // How often to sweep for and expire timed-out claims.
+  EXPIRY_SWEEP_INTERVAL_MS: z.coerce.number().default(5 * 60 * 1000),
 });
 
 export type Config = z.infer<typeof envSchema>;

server/src/db/migrations.ts

@@ -70,4 +70,14 @@ CREATE INDEX idx_links_from ON links(from_place_id);
 CREATE INDEX idx_links_to ON links(to_place_id);
 `,
   },
+  {
+    id: 2,
+    // Block height at claim time — the actual expiry clock (PORTAL_TIMEOUT_BLOCKS
+    // in config.ts), kept alongside the existing wall-clock claimed_at rather than
+    // replacing it, since that's still useful for display/audit. Nullable because
+    // existing rows predate this column; services/expiry.ts backfills them with
+    // the real current height once at server startup (see index.ts) rather than
+    // guessing a historical height from their wall-clock timestamp.
+    sql: `ALTER TABLE claims ADD COLUMN claimed_at_block INTEGER;`,
+  },
 ];

server/src/index.ts

@@ -1,8 +1,38 @@
 import { loadConfig } from './config.js';
 import { buildApp } from './app.js';
+import { backfillMissingClaimedAtBlock, sweepExpiredClaims } from './services/expiry.js';
 
 const config = loadConfig();
 const app = await buildApp({ config });
+const { db, blockHeight } = app.ctx;
+
+try {
+  const startupHeight = await blockHeight.getCurrent();
+  const backfilled = backfillMissingClaimedAtBlock(db, startupHeight);
+  if (backfilled > 0) {
+    app.log.info(`backfilled claimed_at_block for ${backfilled} pre-existing claim(s) at height ${startupHeight}`);
+  }
+} catch (err) {
+  app.log.warn(`startup claimed_at_block backfill skipped: ${(err as Error).message}`);
+}
+
+const sweepInterval = setInterval(() => {
+  void (async () => {
+    try {
+      const height = await blockHeight.getCurrent();
+      const expired = sweepExpiredClaims(db, height, config.PORTAL_TIMEOUT_BLOCKS);
+      if (expired.length > 0) {
+        app.log.info(`expired ${expired.length} claim(s) at height ${height}: ${expired.map((c) => c.placeId).join(', ')}`);
+      }
+    } catch (err) {
+      app.log.warn(`expiry sweep failed: ${(err as Error).message}`);
+    }
+  })();
+}, config.EXPIRY_SWEEP_INTERVAL_MS);
+
+app.addHook('onClose', async () => {
+  clearInterval(sweepInterval);
+});
 
 try {
   await app.listen({ port: config.PORT, host: config.HOST });

server/src/routePrefix.test.ts

@@ -6,6 +6,7 @@ import { finalizeEvent, generateSecretKey, getPublicKey } from 'nostr-tools/pure
 import type { FastifyInstance } from 'fastify';
 import { buildApp } from './app.js';
 import { loadConfig } from './config.js';
+import { FakeBlockHeight } from './testUtils/fakeBlockHeight.js';
 
 // Mirrors deploying under e.g. podsteadr.atobitcoin.io/regress/, where nginx
 // forwards the full prefixed path unchanged (not stripped) — see config.ts.
@@ -35,7 +36,7 @@ beforeAll(async () => {
     PUBLIC_URL: 'https://podsteadr.atobitcoin.io',
     ROUTE_PREFIX: '/regress',
   } as NodeJS.ProcessEnv);
-  app = await buildApp({ config, dbPath: ':memory:', logger: false });
+  app = await buildApp({ config, dbPath: ':memory:', logger: false, blockHeight: new FakeBlockHeight(900_000) });
 });
 
 afterAll(async () => {

server/src/routes/claims.ts

@@ -1,6 +1,7 @@
 import type { FastifyInstance } from 'fastify';
 import { z } from 'zod';
 import { haversineMeters } from '../services/geo.js';
+import { isClaimExpired } from '../services/expiry.js';
 import type { Claim, Place, User } from '../types.js';
 
 const claimBody = z.object({
@@ -13,18 +14,19 @@ function nowSecs(): number {
 }
 
 export default async function claimsRoutes(app: FastifyInstance) {
-  const { db, config } = app.ctx;
+  const { db, config, blockHeight } = app.ctx;
 
   const getPlace = db.prepare('SELECT * FROM places WHERE id = ?');
   const getUser = db.prepare('SELECT * FROM users WHERE pubkey = ?');
   const getClaim = db.prepare('SELECT * FROM claims WHERE place_id = ?');
   const deleteLinksTouching = db.prepare('DELETE FROM links WHERE from_place_id = ? OR to_place_id = ?');
   const upsertClaim = db.prepare(`
-    INSERT INTO claims (place_id, team, claimed_by_pubkey, claimed_at) VALUES (?, ?, ?, ?)
+    INSERT INTO claims (place_id, team, claimed_by_pubkey, claimed_at, claimed_at_block) VALUES (?, ?, ?, ?, ?)
     ON CONFLICT(place_id) DO UPDATE SET
       team = excluded.team,
       claimed_by_pubkey = excluded.claimed_by_pubkey,
-      claimed_at = excluded.claimed_at
+      claimed_at = excluded.claimed_at,
+      claimed_at_block = excluded.claimed_at_block
   `);
 
   app.post('/api/places/:id/claim', { preHandler: app.requireAuth }, async (req, reply) => {
@@ -45,19 +47,22 @@ export default async function claimsRoutes(app: FastifyInstance) {
       });
     }
 
+    const currentHeight = await blockHeight.getCurrent();
     const existing = getClaim.get(placeId) as Claim | undefined;
-    if (existing?.team === user.team) {
+    const expired = isClaimExpired(existing, currentHeight, config.PORTAL_TIMEOUT_BLOCKS);
+    if (existing && !expired && existing.team === user.team) {
       return reply.code(409).send({ error: 'already claimed by your team' });
     }
 
-    // Recapturing (or freshly capturing a neutral place) tears down any links
-    // through it — a place can't stay part of an enemy field once it flips,
-    // and a neutral place never had links in the first place so this is a no-op then.
+    // Recapturing (or freshly capturing a neutral/timed-out place) tears down
+    // any links through it — a place can't stay part of a field once it
+    // flips or times out, and a genuinely neutral place never had links in
+    // the first place so this is a no-op then.
     db.transaction(() => {
       deleteLinksTouching.run(placeId, placeId);
-      upsertClaim.run(placeId, user.team, req.userPubkey, nowSecs());
+      upsertClaim.run(placeId, user.team, req.userPubkey, nowSecs(), currentHeight);
     })();
 
-    return { placeId, team: user.team, claimedBy: req.userPubkey };
+    return { placeId, team: user.team, claimedBy: req.userPubkey, claimedAtBlock: currentHeight };
   });
 }

server/src/routes/links.ts

@@ -1,6 +1,7 @@
 import type { FastifyInstance } from 'fastify';
 import { z } from 'zod';
 import { haversineMeters, segmentsIntersect } from '../services/geo.js';
+import { isClaimExpired } from '../services/expiry.js';
 import type { Claim, LinkRow, Place, User } from '../types.js';
 
 const linkBody = z.object({
@@ -15,7 +16,7 @@ function nowSecs(): number {
 }
 
 export default async function linksRoutes(app: FastifyInstance) {
-  const { db, config } = app.ctx;
+  const { db, config, blockHeight } = app.ctx;
 
   const getPlace = db.prepare('SELECT * FROM places WHERE id = ?');
   const getUser = db.prepare('SELECT * FROM users WHERE pubkey = ?');
@@ -43,19 +44,31 @@ export default async function linksRoutes(app: FastifyInstance) {
     const toPlace = getPlace.get(toPlaceId) as Place | undefined;
     if (!fromPlace || !toPlace) return reply.code(404).send({ error: 'place not found' });
 
+    const currentHeight = await blockHeight.getCurrent();
     const fromClaim = getClaim.get(fromPlaceId) as Claim | undefined;
     const toClaim = getClaim.get(toPlaceId) as Claim | undefined;
-    if (fromClaim?.team !== user.team || toClaim?.team !== user.team) {
+    const fromExpired = isClaimExpired(fromClaim, currentHeight, config.PORTAL_TIMEOUT_BLOCKS);
+    const toExpired = isClaimExpired(toClaim, currentHeight, config.PORTAL_TIMEOUT_BLOCKS);
+    if (fromExpired || toExpired || fromClaim?.team !== user.team || toClaim?.team !== user.team) {
       return reply.code(403).send({ error: 'both places must be claimed by your team' });
     }
 
     // You must be physically at the origin portal to link out from it — same
-    // "hack a portal to get a key" presence requirement as Ingress. No range
-    // limit on the link's total length (per game design decision).
-    const distance = haversineMeters({ lat, lon }, fromPlace);
-    if (distance > config.CLAIM_RADIUS_METERS) {
+    // "hack a portal to get a key" presence requirement as Ingress.
+    const originDistance = haversineMeters({ lat, lon }, fromPlace);
+    if (originDistance > config.CLAIM_RADIUS_METERS) {
       return reply.code(403).send({
-        error: `too far from the origin place: ${Math.round(distance)}m (must be within ${config.CLAIM_RADIUS_METERS}m)`,
+        error: `too far from the origin place: ${Math.round(originDistance)}m (must be within ${config.CLAIM_RADIUS_METERS}m)`,
+      });
+    }
+
+    // Flat cap on link length — Ingress scales this off portal/resonator
+    // level, which Regress has no equivalent of, so this is a single fixed
+    // ceiling instead (config.MAX_LINK_DISTANCE_KM).
+    const linkDistanceKm = haversineMeters(fromPlace, toPlace) / 1000;
+    if (linkDistanceKm > config.MAX_LINK_DISTANCE_KM) {
+      return reply.code(403).send({
+        error: `link too long: ${linkDistanceKm.toFixed(1)}km (max ${config.MAX_LINK_DISTANCE_KM}km)`,
       });
     }
 

server/src/routes/places.ts

@@ -4,13 +4,13 @@ export default async function placesRoutes(app: FastifyInstance) {
   const { db } = app.ctx;
 
   const listPlaces = db.prepare(`
-    SELECT p.*, c.team AS claim_team, c.claimed_by_pubkey, c.claimed_at
+    SELECT p.*, c.team AS claim_team, c.claimed_by_pubkey, c.claimed_at, c.claimed_at_block
     FROM places p
     LEFT JOIN claims c ON c.place_id = p.id
     ORDER BY p.id
   `);
   const getPlace = db.prepare(`
-    SELECT p.*, c.team AS claim_team, c.claimed_by_pubkey, c.claimed_at
+    SELECT p.*, c.team AS claim_team, c.claimed_by_pubkey, c.claimed_at, c.claimed_at_block
     FROM places p
     LEFT JOIN claims c ON c.place_id = p.id
     WHERE p.id = ?

server/src/services/blockHeight.ts

@@ -0,0 +1,31 @@
+// Current Bitcoin block height — the game's expiry clock (see PORTAL_TIMEOUT_BLOCKS
+// in config.ts). Pulled from a public block explorer API, same trust model as
+// pulling place data from BTC Map: no local node dependency, no auth needed.
+
+const CACHE_TTL_MS = 60_000;
+
+/** Structural interface so tests can inject a fake without hitting the real network. */
+export interface BlockHeightProvider {
+  getCurrent(): Promise<number>;
+}
+
+export class BlockHeightService implements BlockHeightProvider {
+  private cached: { height: number; fetchedAt: number } | null = null;
+
+  constructor(private apiUrl: string) {}
+
+  async getCurrent(): Promise<number> {
+    if (this.cached && Date.now() - this.cached.fetchedAt < CACHE_TTL_MS) {
+      return this.cached.height;
+    }
+    const res = await fetch(this.apiUrl);
+    if (!res.ok) throw new Error(`block height fetch failed: ${res.status} ${res.statusText}`);
+    const text = (await res.text()).trim();
+    const height = Number(text);
+    if (!Number.isInteger(height) || height <= 0) {
+      throw new Error(`block height endpoint returned unexpected value: ${JSON.stringify(text)}`);
+    }
+    this.cached = { height, fetchedAt: Date.now() };
+    return height;
+  }
+}

server/src/services/expiry.test.ts

@@ -0,0 +1,133 @@
+import { describe, expect, it } from 'vitest';
+import { openDatabase } from '../db/database.js';
+import { backfillMissingClaimedAtBlock, findExpiredClaims, isClaimExpired, sweepExpiredClaims } from './expiry.js';
+import type { Claim } from '../types.js';
+
+function seedPlace(db: ReturnType<typeof openDatabase>, id: number) {
+  db.prepare('INSERT INTO places (id, lat, lon, name, synced_at) VALUES (?, ?, ?, ?, ?)').run(
+    id,
+    10,
+    10 + id,
+    `place-${id}`,
+    0,
+  );
+}
+
+function seedUser(db: ReturnType<typeof openDatabase>, pubkey: string, team: 'orange' | 'green') {
+  db.prepare('INSERT INTO users (pubkey, team, created_at, last_login_at) VALUES (?, ?, 0, 0)').run(pubkey, team);
+}
+
+function seedClaim(
+  db: ReturnType<typeof openDatabase>,
+  placeId: number,
+  team: 'orange' | 'green',
+  pubkey: string,
+  claimedAtBlock: number | null,
+) {
+  db.prepare(
+    'INSERT INTO claims (place_id, team, claimed_by_pubkey, claimed_at, claimed_at_block) VALUES (?, ?, ?, 0, ?)',
+  ).run(placeId, team, pubkey, claimedAtBlock);
+}
+
+describe('isClaimExpired', () => {
+  it('is false for undefined claim', () => {
+    expect(isClaimExpired(undefined, 900_100, 2100)).toBe(false);
+  });
+
+  it('is false when claimed_at_block is null (pre-migration row not yet backfilled)', () => {
+    const claim = { claimed_at_block: null } as Claim;
+    expect(isClaimExpired(claim, 900_100, 2100)).toBe(false);
+  });
+
+  it('is false just under the timeout', () => {
+    const claim = { claimed_at_block: 900_000 } as Claim;
+    expect(isClaimExpired(claim, 900_000 + 2099, 2100)).toBe(false);
+  });
+
+  it('is true exactly at the timeout', () => {
+    const claim = { claimed_at_block: 900_000 } as Claim;
+    expect(isClaimExpired(claim, 900_000 + 2100, 2100)).toBe(true);
+  });
+
+  it('is true well past the timeout', () => {
+    const claim = { claimed_at_block: 900_000 } as Claim;
+    expect(isClaimExpired(claim, 900_000 + 5000, 2100)).toBe(true);
+  });
+});
+
+describe('findExpiredClaims / sweepExpiredClaims', () => {
+  it('finds and expires only claims past the timeout, tearing down their links', () => {
+    const db = openDatabase(':memory:');
+    seedPlace(db, 1);
+    seedPlace(db, 2);
+    seedPlace(db, 3);
+    seedUser(db, 'pk1', 'orange');
+    seedClaim(db, 1, 'orange', 'pk1', 900_000); // will be expired
+    seedClaim(db, 2, 'orange', 'pk1', 899_000); // long expired
+    seedClaim(db, 3, 'orange', 'pk1', 902_000); // still fresh
+    db.prepare(
+      'INSERT INTO links (from_place_id, to_place_id, team, created_by_pubkey, created_at) VALUES (1, 2, ?, ?, 0)',
+    ).run('orange', 'pk1');
+
+    const currentHeight = 902_100; // 2100 blocks past place 1 and 2, not place 3
+    const found = findExpiredClaims(db, currentHeight, 2100);
+    expect(found.map((c) => c.placeId).sort()).toEqual([1, 2]);
+
+    const swept = sweepExpiredClaims(db, currentHeight, 2100);
+    expect(swept.map((c) => c.placeId).sort()).toEqual([1, 2]);
+
+    const remainingClaims = db.prepare('SELECT place_id FROM claims').all() as { place_id: number }[];
+    expect(remainingClaims.map((c) => c.place_id)).toEqual([3]);
+
+    const remainingLinks = db.prepare('SELECT * FROM links').all();
+    expect(remainingLinks).toHaveLength(0); // the 1-2 link died with either endpoint expiring
+
+    db.close();
+  });
+
+  it('is a no-op when nothing has expired', () => {
+    const db = openDatabase(':memory:');
+    seedPlace(db, 1);
+    seedUser(db, 'pk1', 'orange');
+    seedClaim(db, 1, 'orange', 'pk1', 900_000);
+
+    expect(sweepExpiredClaims(db, 900_500, 2100)).toHaveLength(0);
+    expect(db.prepare('SELECT COUNT(*) c FROM claims').get()).toEqual({ c: 1 });
+
+    db.close();
+  });
+
+  it('ignores claims with no claimed_at_block yet (not backfilled)', () => {
+    const db = openDatabase(':memory:');
+    seedPlace(db, 1);
+    seedUser(db, 'pk1', 'orange');
+    seedClaim(db, 1, 'orange', 'pk1', null);
+
+    expect(sweepExpiredClaims(db, 999_999_999, 2100)).toHaveLength(0);
+    expect(db.prepare('SELECT COUNT(*) c FROM claims').get()).toEqual({ c: 1 });
+
+    db.close();
+  });
+});
+
+describe('backfillMissingClaimedAtBlock', () => {
+  it('sets claimed_at_block only for rows where it is currently null', () => {
+    const db = openDatabase(':memory:');
+    seedPlace(db, 1);
+    seedPlace(db, 2);
+    seedUser(db, 'pk1', 'orange');
+    seedClaim(db, 1, 'orange', 'pk1', null);
+    seedClaim(db, 2, 'orange', 'pk1', 500_000); // already has one — must not be overwritten
+
+    const changed = backfillMissingClaimedAtBlock(db, 900_000);
+    expect(changed).toBe(1);
+
+    const rows = db.prepare('SELECT place_id, claimed_at_block FROM claims ORDER BY place_id').all();
+    expect(rows).toEqual([
+      { place_id: 1, claimed_at_block: 900_000 },
+      { place_id: 2, claimed_at_block: 500_000 },
+    ]);
+
+    db.close();
+  });
+});

server/src/services/expiry.ts

@@ -0,0 +1,58 @@
+import type { DB } from '../db/database.js';
+import type { Claim } from '../types.js';
+
+export interface ExpiredClaim {
+  placeId: number;
+  team: string;
+  claimedAtBlock: number;
+}
+
+export function isClaimExpired(
+  claim: Claim | undefined,
+  currentHeight: number,
+  timeoutBlocks: number,
+): boolean {
+  if (!claim || claim.claimed_at_block == null) return false;
+  return currentHeight - claim.claimed_at_block >= timeoutBlocks;
+}
+
+export function findExpiredClaims(db: DB, currentHeight: number, timeoutBlocks: number): ExpiredClaim[] {
+  return db
+    .prepare(
+      `SELECT place_id AS placeId, team, claimed_at_block AS claimedAtBlock
+       FROM claims
+       WHERE claimed_at_block IS NOT NULL AND (? - claimed_at_block) >= ?`,
+    )
+    .all(currentHeight, timeoutBlocks) as ExpiredClaim[];
+}
+
+/**
+ * Expires timed-out claims back to neutral — deletes the claim row and tears
+ * down any links through it, same as a normal recapture (see routes/claims.ts).
+ * Returns what was expired, for logging.
+ */
+export function sweepExpiredClaims(db: DB, currentHeight: number, timeoutBlocks: number): ExpiredClaim[] {
+  const expired = findExpiredClaims(db, currentHeight, timeoutBlocks);
+  if (expired.length === 0) return expired;
+
+  const deleteLinksTouching = db.prepare('DELETE FROM links WHERE from_place_id = ? OR to_place_id = ?');
+  const deleteClaim = db.prepare('DELETE FROM claims WHERE place_id = ?');
+  db.transaction(() => {
+    for (const c of expired) {
+      deleteLinksTouching.run(c.placeId, c.placeId);
+      deleteClaim.run(c.placeId);
+    }
+  })();
+  return expired;
+}
+
+/**
+ * One-time backfill for claims that predate the claimed_at_block column —
+ * stamped with the real current height at the moment this runs (see
+ * index.ts), giving them a fresh full timeout window from server startup
+ * rather than guessing a historical height from their wall-clock timestamp.
+ */
+export function backfillMissingClaimedAtBlock(db: DB, currentHeight: number): number {
+  return db.prepare('UPDATE claims SET claimed_at_block = ? WHERE claimed_at_block IS NULL').run(currentHeight)
+    .changes;
+}

server/src/testUtils/fakeBlockHeight.ts

@@ -0,0 +1,10 @@
+import type { BlockHeightProvider } from '../services/blockHeight.js';
+
+/** Deterministic, network-free stand-in for tests. Mutable so tests can advance the "chain". */
+export class FakeBlockHeight implements BlockHeightProvider {
+  constructor(public height: number) {}
+
+  async getCurrent(): Promise<number> {
+    return this.height;
+  }
+}

server/src/types.ts

@@ -25,6 +25,7 @@ export interface Claim {
   team: Team;
   claimed_by_pubkey: string;
   claimed_at: number;
+  claimed_at_block: number | null;
 }
 
 export interface LinkRow {