Single-flight discovery harvester with budgets and stop reasons (BL-0051)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

discovery/harvest.js

@@ -0,0 +1,152 @@
+'use strict';
+
+const crypto = require('node:crypto');
+const { AniListStop, AniListSkip } = require('./anilist');
+const { topTagsFor } = require('./anchors');
+
+const BUDGETS = { nightly: 300, admin: 300, user: 60 };
+const REFRESH_COOLDOWN_MS = 3600000;
+const MAX_CONSECUTIVE_FAILURES = 5;
+const CREATOR_MIN_WEIGHT = 3;
+
+// Thrown out of a run to unwind every stage at once.
+class StopRun extends Error {
+  constructor(status, stopReason) { super(stopReason); this.status = status; this.stopReason = stopReason; }
+}
+
+async function runHarvest({ kind, targets, cache, client, budget }) {
+  let requests = 0, failures = 0;
+  const seen = new Set();
+  // One request: skipped when already done this run or still fresh in the cache, otherwise awaited in turn.
+  const fetchInto = async (cacheKind, key, call) => {
+    const id = `${cacheKind}\n${key}`;
+    if (seen.has(id)) return;
+    seen.add(id);
+    if (cache.isFresh(cacheKind, key)) return;
+    if (requests >= budget) throw new StopRun('success', 'budget');
+    requests++;
+    let data;
+    try { data = await call(); }
+    catch (error) {
+      if (error instanceof AniListStop) throw new StopRun('stopped', error.reason);
+      if (!(error instanceof AniListSkip)) throw error;
+      if (++failures >= MAX_CONSECUTIVE_FAILURES) throw new StopRun('stopped', 'upstream-errors');
+      return;
+    }
+    failures = 0;
+    // A null title is not a manga format: nothing worth keeping.
+    if (data !== null) cache.put(cacheKind, key, data);
+  };
+
+  const anchors = targets.flatMap(target => target.anchors);
+  const recordOf = id => cache.get('title', id)?.data || null;
+  try {
+    for (const { anilistId } of anchors) await fetchInto('title', anilistId, () => client.title(anilistId));
+    for (const { anilistId } of anchors) await fetchInto('recs', anilistId, () => client.recs(anilistId));
+    for (const anchor of anchors) {
+      if (anchor.weight < CREATOR_MIN_WEIGHT) continue;
+      for (const { staffId } of recordOf(anchor.anilistId)?.authors || [])
+        await fetchInto('creator', staffId, () => client.creator(staffId));
+    }
+    for (const target of targets) {
+      for (const tag of topTagsFor(target.anchors, recordOf, { mature: target.mature }))
+        await fetchInto('tagTop', `${tag.kind}:${tag.name}`, () => client.tagTop(tag));
+    }
+    // With nobody to harvest for, even the global list is not worth a request.
+    if (targets.length) await fetchInto('fresh', 'global', () => client.fresh());
+  } catch (error) {
+    if (!(error instanceof StopRun)) throw error;
+    return { requests, budget, status: error.status, stopReason: error.stopReason };
+  }
+  return { requests, budget, status: 'success', stopReason: null };
+}
+
+const localDate = date => [date.getFullYear(), String(date.getMonth() + 1).padStart(2, '0'),
+  String(date.getDate()).padStart(2, '0')].join('-');
+
+function shouldRunNightly({ now, harvestAt, lastNightlyDate, enabled }) {
+  if (!enabled) return false;
+  const match = /^(\d{2}):(\d{2})$/.exec(harvestAt || '');
+  if (!match) return false;
+  if (now.getHours() * 60 + now.getMinutes() < Number(match[1]) * 60 + Number(match[2])) return false;
+  return localDate(now) !== lastNightlyDate;
+}
+
+const httpError = (status, message, extra = {}) => Object.assign(new Error(message), { status }, extra);
+
+class Harvester {
+  constructor({ cache, client, store, targetsFor, onDone, now = Date.now }) {
+    Object.assign(this, { cache, client, store, targetsFor, onDone, now });
+    this.queue = [];
+    this.active = null;
+    this.lastAccepted = new Map();
+  }
+  nextAllowedAt(user) {
+    const last = this.lastAccepted.get(user);
+    if (last === undefined || this.now() - last >= REFRESH_COOLDOWN_MS) return null;
+    return new Date(last + REFRESH_COOLDOWN_MS).toISOString();
+  }
+  jobs() { return [this.active, ...this.queue].filter(Boolean); }
+  request({ kind, user }) {
+    if (!(kind in BUDGETS)) throw httpError(400, `Unknown harvest kind: ${kind}`);
+    if (kind === 'user') {
+      if (!user) throw httpError(400, 'A user refresh needs a user');
+      if (this.jobs().some(job => job.kind === 'user' && job.user === user))
+        throw httpError(409, 'A refresh for this user is already queued or running');
+      const nextAllowedAt = this.nextAllowedAt(user);
+      if (nextAllowedAt) throw httpError(429, 'Refresh is cooling down', { nextAllowedAt });
+      this.lastAccepted.set(user, this.now());
+    } else if (this.jobs().length) {
+      throw httpError(409, 'A harvest is already queued or running');
+    }
+    const job = { id: crypto.randomBytes(8).toString('hex'), kind, ...(kind === 'user' ? { user } : {}) };
+    const position = this.jobs().length;
+    this.queue.push(job);
+    if (!this.active) this.drain();
+    return { harvestId: job.id, position };
+  }
+  state(userName) {
+    const nextAllowedAt = this.nextAllowedAt(userName);
+    const cooldown = nextAllowedAt ? { nextAllowedAt } : {};
+    const index = this.jobs().findIndex(job => job.kind === 'user' && job.user === userName);
+    if (index === 0 && this.active) return { state: 'running', ...cooldown };
+    if (index >= 0) return { state: 'queued', position: index, ...cooldown };
+    return { state: 'idle', ...cooldown };
+  }
+  current() {
+    if (!this.active) return null;
+    const { id, kind, user, startedAt } = this.active;
+    return { id, kind, ...(user ? { user } : {}), startedAt };
+  }
+  // Runs synchronously up to the first await, so a job is active before request() returns.
+  async drain() {
+    while (this.queue.length) {
+      const job = this.queue.shift();
+      job.startedAt = new Date(this.now()).toISOString();
+      this.active = job;
+      try { await this.run(job); }
+      catch (error) { console.error(`Discovery harvest ${job.id} failed:`, error); }
+      finally { this.active = null; }
+    }
+  }
+  async run(job) {
+    const budget = BUDGETS[job.kind];
+    const base = { id: job.id, kind: job.kind, user: job.user ?? null };
+    await this.store.patch({ harvest: { ...base, status: 'running', startedAt: job.startedAt, requests: 0, budget } });
+    let result;
+    try {
+      const targets = this.targetsFor(job.kind, job.user);
+      result = await runHarvest({ kind: job.kind, targets, cache: this.cache, client: this.client, budget });
+    } catch (error) {
+      // A local fault (cache write, bad target) must not leave the record "running" until restart.
+      console.error(`Discovery harvest ${job.id} failed:`, error);
+      result = { requests: 0, budget, status: 'stopped', stopReason: 'error' };
+    }
+    await this.store.patch({ harvest: { ...base, status: result.status, startedAt: job.startedAt,
+      finishedAt: new Date(this.now()).toISOString(), requests: result.requests, budget, stopReason: result.stopReason } });
+    try { await this.onDone(job, result); }
+    catch (error) { console.error(`Discovery harvest ${job.id} follow-up failed:`, error); }
+  }
+}
+
+module.exports = { BUDGETS, REFRESH_COOLDOWN_MS, MAX_CONSECUTIVE_FAILURES, runHarvest, shouldRunNightly, Harvester };

test/discovery-harvest.test.js

@@ -0,0 +1,261 @@
+'use strict';
+
+const test = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const os = require('node:os');
+const path = require('node:path');
+const { DiscoveryCache } = require('../discovery/cache');
+const { AniListStop, AniListSkip } = require('../discovery/anilist');
+const {
+  BUDGETS, REFRESH_COOLDOWN_MS, MAX_CONSECUTIVE_FAILURES, runHarvest, shouldRunNightly, Harvester,
+} = require('../discovery/harvest');
+
+const tempCache = (t) => {
+  const dir = fs.mkdtempSync(path.join(os.tmpdir(), 'discovery-harvest-'));
+  t.after(() => fs.rmSync(dir, { recursive: true, force: true }));
+  return new DiscoveryCache(dir);
+};
+
+const record = (id, { tags = [], authors = [] } = {}) => ({ anilistId: id, title: `T${id}`, tags, authors });
+
+// Fake client: answers from fixture maps, logs every call, and throws scripted errors by call number.
+function fakeClient({ titles = {}, errors = {} } = {}) {
+  const calls = [];
+  const answer = (name, key, value) => {
+    calls.push(`${name}:${key}`);
+    const error = errors[calls.length];
+    if (error) throw error;
+    return value;
+  };
+  return {
+    calls,
+    async title(id) { return answer('title', id, id in titles ? titles[id] : record(id)); },
+    async recs(id) { return answer('recs', id, [{ anilistId: id * 100 }]); },
+    async creator(staffId) { return answer('creator', staffId, [{ anilistId: staffId * 10 }]); },
+    async tagTop({ name, kind }) { return answer('tagTop', `${kind}:${name}`, [{ anilistId: 1 }]); },
+    async fresh() { return answer('fresh', 'global', [{ anilistId: 2 }]); },
+  };
+}
+
+const anchor = (anilistId, weight = 1) => ({ anilistId, weight, source: 'owned', title: null });
+
+test('constants', () => {
+  assert.deepEqual(BUDGETS, { nightly: 300, admin: 300, user: 60 });
+  assert.equal(REFRESH_COOLDOWN_MS, 3600000);
+  assert.equal(MAX_CONSECUTIVE_FAILURES, 5);
+});
+
+test('plan order and dedupe', async (t) => {
+  const cache = tempCache(t);
+  const titles = {
+    1: record(1, { tags: [{ name: 'Drama', kind: 'genre', rank: 100, isAdult: false }], authors: [{ staffId: 9, name: 'A', role: 'Story' }] }),
+    2: record(2, { tags: [{ name: 'Drama', kind: 'genre', rank: 100, isAdult: false }] }),
+    3: record(3, { tags: [{ name: 'Gore', kind: 'tag', rank: 80, isAdult: false }], authors: [{ staffId: 8, name: 'B', role: 'Art' }] }),
+  };
+  const client = fakeClient({ titles });
+  const targets = [
+    { user: 'ann', anchors: [anchor(1, 5), anchor(2, 1)], mature: false },
+    { user: 'bob', anchors: [anchor(1, 3), anchor(3, 1)], mature: false },
+  ];
+  const result = await runHarvest({ kind: 'admin', targets, cache, client, budget: 300 });
+  assert.deepEqual(client.calls, [
+    'title:1', 'title:2', 'title:3',
+    'recs:1', 'recs:2', 'recs:3',
+    'creator:9',
+    'tagTop:genre:Drama', 'tagTop:tag:Gore',
+    'fresh:global',
+  ]);
+  assert.deepEqual(result, { requests: 10, budget: 300, status: 'success', stopReason: null });
+  assert.equal(cache.get('title', 1).data.anilistId, 1);
+  assert.deepEqual(cache.get('recs', 2).data, [{ anilistId: 200 }]);
+  assert.deepEqual(cache.get('creator', 9).data, [{ anilistId: 90 }]);
+  assert.deepEqual(cache.get('tagTop', 'genre:Drama').data, [{ anilistId: 1 }]);
+  assert.deepEqual(cache.get('fresh', 'global').data, [{ anilistId: 2 }]);
+});
+
+test('non-manga titles are counted but not cached', async (t) => {
+  const cache = tempCache(t);
+  const client = fakeClient({ titles: { 4: null } });
+  const result = await runHarvest({ kind: 'user', targets: [{ user: 'ann', anchors: [anchor(4, 5)], mature: false }], cache, client, budget: 60 });
+  assert.equal(cache.get('title', 4), null);
+  assert.deepEqual(client.calls, ['title:4', 'recs:4', 'fresh:global']);
+  assert.equal(result.requests, 3);
+});
+
+test('fresh cache entries are skipped', async (t) => {
+  const cache = tempCache(t);
+  cache.put('title', 1, record(1));
+  cache.put('recs', 1, []);
+  cache.put('fresh', 'global', []);
+  const client = fakeClient();
+  const result = await runHarvest({ kind: 'user', targets: [{ user: 'ann', anchors: [anchor(1), anchor(2)], mature: false }], cache, client, budget: 60 });
+  assert.deepEqual(client.calls, ['title:2', 'recs:2']);
+  assert.equal(result.requests, 2);
+  assert.equal(result.stopReason, null);
+});
+
+test('budget stops with reason budget', async (t) => {
+  const cache = tempCache(t);
+  const client = fakeClient();
+  const targets = [{ user: 'ann', anchors: [anchor(1), anchor(2), anchor(3)], mature: false }];
+  const result = await runHarvest({ kind: 'user', targets, cache, client, budget: 3 });
+  assert.deepEqual(result, { requests: 3, budget: 3, status: 'success', stopReason: 'budget' });
+  assert.equal(client.calls.length, 3);
+});
+
+test('429 stops at once', async (t) => {
+  const cache = tempCache(t);
+  const client = fakeClient({ errors: { 2: new AniListStop('rate-limited') } });
+  const targets = [{ user: 'ann', anchors: [anchor(1), anchor(2), anchor(3)], mature: false }];
+  const result = await runHarvest({ kind: 'admin', targets, cache, client, budget: 300 });
+  assert.deepEqual(result, { requests: 2, budget: 300, status: 'stopped', stopReason: 'rate-limited' });
+  assert.equal(client.calls.length, 2);
+  assert.equal(cache.get('title', 2), null);
+});
+
+test('network error stops with upstream-errors after 5', async (t) => {
+  const skip = () => new AniListSkip('timeout');
+  const targets = [{ user: 'ann', anchors: [1, 2, 3, 4, 5, 6, 7, 8].map((id) => anchor(id)), mature: false }];
+
+  const client = fakeClient({ errors: { 1: skip(), 2: skip(), 3: skip(), 4: skip(), 5: skip() } });
+  const result = await runHarvest({ kind: 'admin', targets, cache: tempCache(t), client, budget: 300 });
+  assert.deepEqual(result, { requests: 5, budget: 300, status: 'stopped', stopReason: 'upstream-errors' });
+  assert.equal(client.calls.length, 5);
+
+  // A success in the middle resets the counter, so the run gets past five failures in total.
+  const mixed = fakeClient({ errors: { 1: skip(), 2: skip(), 3: skip(), 4: skip(), 6: skip(), 7: skip(), 8: skip() } });
+  const reset = await runHarvest({ kind: 'admin', targets, cache: tempCache(t), client: mixed, budget: 300 });
+  assert.equal(reset.status, 'success');
+  assert.equal(reset.stopReason, null);
+  assert.ok(mixed.calls.length > 8);
+});
+
+test('plan for anchorless user only fetches fresh', async (t) => {
+  const client = fakeClient();
+  const result = await runHarvest({ kind: 'user', targets: [{ user: 'ann', anchors: [], mature: false }], cache: tempCache(t), client, budget: 60 });
+  assert.deepEqual(client.calls, ['fresh:global']);
+  assert.deepEqual(result, { requests: 1, budget: 60, status: 'success', stopReason: null });
+});
+
+test('shouldRunNightly', () => {
+  const at = (h, m) => new Date(2026, 9, 25, h, m);
+  assert.equal(shouldRunNightly({ now: at(3, 29), harvestAt: '03:30', lastNightlyDate: null, enabled: true }), false);
+  assert.equal(shouldRunNightly({ now: at(3, 30), harvestAt: '03:30', lastNightlyDate: null, enabled: true }), true);
+  assert.equal(shouldRunNightly({ now: at(23, 0), harvestAt: '03:30', lastNightlyDate: '2026-10-24', enabled: true }), true);
+  assert.equal(shouldRunNightly({ now: at(3, 30), harvestAt: '03:30', lastNightlyDate: '2026-10-25', enabled: true }), false);
+  assert.equal(shouldRunNightly({ now: at(3, 30), harvestAt: '03:30', lastNightlyDate: null, enabled: false }), false);
+});
+
+// A run that waits until the test releases it, so queue state can be observed.
+function gatedHarvester({ onDone = async () => {}, now }) {
+  const gates = [];
+  const patches = [];
+  const done = [];
+  const client = {
+    calls: [],
+    async fresh() {
+      this.calls.push('fresh');
+      await new Promise((resolve) => gates.push(resolve));
+      return [];
+    },
+  };
+  // Nothing stays cached, so every job makes its one fresh call and waits at the gate.
+  const cache = { isFresh: () => false, get: () => null, put() {} };
+  const harvester = new Harvester({
+    cache,
+    client,
+    store: { patch(value) { patches.push(structuredClone(value)); } },
+    targetsFor: (kind, user) => [{ user: user || 'all', anchors: [], mature: false }],
+    onDone: async (job, result) => { done.push({ job, result }); await onDone(job, result); },
+    now,
+  });
+  const release = async () => {
+    for (let i = 0; !gates.length; i++) {
+      if (i > 1000) throw new Error('no harvest request is waiting');
+      await new Promise(setImmediate);
+    }
+    gates.shift()();
+    await new Promise(setImmediate);
+  };
+  return { harvester, patches, done, release, client };
+}
+
+const settle = async () => { for (let i = 0; i < 20; i++) await new Promise(setImmediate); };
+
+test('harvester single-flight, positions, 409 and 429 cooldown', async (t) => {
+  let clock = Date.parse('2026-10-25T10:00:00Z');
+  const h = gatedHarvester({ now: () => clock });
+  const { harvester } = h;
+
+  assert.deepEqual(harvester.state('ann'), { state: 'idle' });
+  assert.equal(harvester.current(), null);
+
+  const first = harvester.request({ kind: 'user', user: 'ann' });
+  assert.equal(first.position, 0);
+  assert.equal(typeof first.harvestId, 'string');
+  assert.equal(harvester.state('ann').state, 'running');
+  assert.deepEqual(harvester.current(), { id: first.harvestId, kind: 'user', user: 'ann', startedAt: '2026-10-25T10:00:00.000Z' });
+
+  assert.throws(() => harvester.request({ kind: 'admin' }), (error) => error.status === 409);
+  assert.throws(() => harvester.request({ kind: 'nightly' }), (error) => error.status === 409);
+  assert.throws(() => harvester.request({ kind: 'user', user: 'ann' }), (error) => error.status === 409);
+
+  const second = harvester.request({ kind: 'user', user: 'bob' });
+  assert.equal(second.position, 1);
+  assert.deepEqual(harvester.state('bob'), { state: 'queued', position: 1, nextAllowedAt: '2026-10-25T11:00:00.000Z' });
+  assert.throws(() => harvester.request({ kind: 'user', user: 'bob' }), (error) => error.status === 409);
+
+  await h.release();
+  await settle();
+  assert.equal(harvester.state('bob').state, 'running');
+  assert.equal(harvester.state('ann').state, 'idle');
+
+  clock += 30 * 60000;
+  assert.throws(() => harvester.request({ kind: 'user', user: 'ann' }), (error) => {
+    assert.equal(error.status, 429);
+    assert.equal(error.nextAllowedAt, '2026-10-25T11:00:00.000Z');
+    return true;
+  });
+  assert.deepEqual(harvester.state('ann'), { state: 'idle', nextAllowedAt: '2026-10-25T11:00:00.000Z' });
+
+  await h.release();
+  await settle();
+  assert.equal(harvester.current(), null);
+
+  // The persisted records: running first, then the final one, for each job in order.
+  assert.deepEqual(h.patches.map((p) => [p.harvest.user, p.harvest.status]),
+    [['ann', 'running'], ['ann', 'success'], ['bob', 'running'], ['bob', 'success']]);
+  assert.deepEqual(h.patches[0].harvest, { id: first.harvestId, kind: 'user', user: 'ann', status: 'running',
+    startedAt: '2026-10-25T10:00:00.000Z', requests: 0, budget: 60 });
+  assert.equal(h.patches[1].harvest.requests, 1);
+  assert.equal(h.patches[1].harvest.stopReason, null);
+  assert.equal(typeof h.patches[1].harvest.finishedAt, 'string');
+  assert.deepEqual(h.done.map((d) => d.job.user), ['ann', 'bob']);
+
+  clock += 30 * 60000;
+  const admin = harvester.request({ kind: 'admin' });
+  assert.equal(admin.position, 0);
+  const ann = harvester.request({ kind: 'user', user: 'ann' });
+  assert.equal(ann.position, 1);
+  await h.release();
+  await h.release();
+  await settle();
+  assert.equal(h.patches.at(-4).harvest.budget, 300);
+});
+
+test('onDone failure does not stall the queue', async (t) => {
+  const errors = [];
+  const original = console.error;
+  console.error = (...args) => errors.push(args);
+  t.after(() => { console.error = original; });
+  const h = gatedHarvester({ now: () => Date.parse('2026-10-25T10:00:00Z'), onDone: async () => { throw new Error('score failed'); } });
+  h.harvester.request({ kind: 'nightly' });
+  h.harvester.request({ kind: 'user', user: 'ann' });
+  await h.release();
+  await h.release();
+  await settle();
+  assert.deepEqual(h.done.map((d) => d.job.kind), ['nightly', 'user']);
+  assert.equal(h.harvester.current(), null);
+  assert.ok(errors.length >= 2);
+});