feat: replace MongoDB driver with Cloudflare KV storage

Drops the mongodb dependency entirely; all four logical collections
(admin singleton, group, apple_app, google_app) now live in a single KV
namespace bound as STORE_KV with prefixed keys. Cache TTL is delegated
to KV via expirationTtl (clamped to the 60s minimum). Document shape,
field names, and Java parity at the doc level are preserved.

- Adds src/repository/kv.js helper (getJson/putJson/del with TTL clamp)
- Rewrites all four *-repository.js modules on top of KV
- Removes src/repository/mongodb.js and the MONGODB_URI env requirement
- Adds an early STORE_KV-binding guard in src/index.js
- Bumps to 0.3.0

package.json

@@ -1,7 +1,7 @@
 {
   "name": "js-store-scraper-bot",
-  "version": "0.2.0",
-  "description": "JavaScript port of store-scraper-bot — Telegram bot tracking Apple App Store + Google Play app updates. Deploys to Cloudflare Workers.",
+  "version": "0.3.0",
+  "description": "JavaScript port of store-scraper-bot — Telegram bot tracking Apple App Store + Google Play app updates. Deploys to Cloudflare Workers, backed by Cloudflare KV.",
   "type": "module",
   "private": true,
   "engines": {
@@ -15,9 +15,6 @@
     "register:dry": "node --env-file=.env.deploy scripts/register-webhook.js --dry-run",
     "lint": "node scripts/check-secret-leaks.js"
   },
-  "dependencies": {
-    "mongodb": "^6.10.0"
-  },
   "devDependencies": {
     "wrangler": "^3.90.0"
   },

src/config.js

@@ -16,7 +16,6 @@ export function loadConfig(env) {
     'TELEGRAM_BOT_TOKEN',
     'TELEGRAM_BOT_USERNAME',
     'TELEGRAM_WEBHOOK_SECRET',
-    'MONGODB_URI',
     'ADMIN_IDS',
   ];
   for (const k of required) {

src/index.js

@@ -6,9 +6,10 @@ import { createBot } from './bot/bot.js';
 import { dispatch } from './bot/dispatch.js';
 import { runDailyCheck } from './scheduler/scheduler.js';
 
-// Builds the per-invocation context. Cheap; relies on memoized MongoClient
-// inside the store factory chain.
+// Builds the per-invocation context. Cheap — KV binding is exposed by the
+// runtime; no connection setup needed.
 function build(env) {
+  if (!env.STORE_KV) throw new Error('STORE_KV binding missing');
   const config = loadConfig(env);
   const store = createStore(env, config.appCacheSeconds);
   const appleScraper = createAppleScraper(config, store);
@@ -19,7 +20,7 @@ function build(env) {
 
 export default {
   // Telegram webhook entry. Validates the `secret_token` header, acks fast,
-  // then dispatches in `ctx.waitUntil` so Telegram doesn't retry on slow Mongo.
+  // then dispatches in `ctx.waitUntil` so Telegram doesn't retry on slow downstream calls.
   async fetch(request, env, ctx) {
     if (request.method !== 'POST') {
       return new Response('Not found', { status: 404 });

src/models/apple-app.js

@@ -1,8 +1,5 @@
 // AppleApp cache entry — Java parity (_id=appId, class="AppleApp").
+// TTL is enforced by Cloudflare KV via expirationTtl, so no isExpired helper.
 export function newAppleApp(appId, response, millis) {
   return { _id: appId, class: 'AppleApp', app: response, millis };
 }
-
-export function isAppleAppExpired(entry, nowMillis, cacheMillis) {
-  return nowMillis - entry.millis > cacheMillis;
-}

src/models/google-app.js

@@ -1,8 +1,5 @@
 // GoogleApp cache entry — Java parity (_id=appId, class="GoogleApp").
+// TTL is enforced by Cloudflare KV via expirationTtl, so no isExpired helper.
 export function newGoogleApp(appId, response, millis) {
   return { _id: appId, class: 'GoogleApp', app: response, millis };
 }
-
-export function isGoogleAppExpired(entry, nowMillis, cacheMillis) {
-  return nowMillis - entry.millis > cacheMillis;
-}

src/repository/admin-repository.js

@@ -1,4 +1,4 @@
-import { getCollection } from './mongodb.js';
+import { getJson, putJson } from './kv.js';
 import {
   ADMIN_ID,
   adminAddGroup,
@@ -7,28 +7,22 @@ import {
   newAdmin,
 } from '../models/admin.js';
 
-// Stored in "common" collection at _id="admin" (Java parity).
+// KV-backed admin singleton — Java parity at the document level
+// (key 'admin' holds the same shape Mongo stored at _id="admin").
 export function createAdminRepository(env) {
-  function collection() {
-    return getCollection('common', env);
-  }
-
   async function init() {
-    const c = await collection();
-    const count = await c.countDocuments({ _id: ADMIN_ID });
-    if (count > 0) return;
+    const existing = await getJson(env, ADMIN_ID);
+    if (existing) return;
     await save(newAdmin());
   }
 
   async function getAdmin() {
-    const c = await collection();
-    const doc = await c.findOne({ _id: ADMIN_ID });
+    const doc = await getJson(env, ADMIN_ID);
     return doc ?? newAdmin();
   }
 
   async function save(admin) {
-    const c = await collection();
-    await c.replaceOne({ _id: ADMIN_ID }, admin, { upsert: true });
+    await putJson(env, ADMIN_ID, admin);
   }
 
   async function addGroup(groupId) {

src/repository/apple-app-repository.js

@@ -1,26 +1,23 @@
-import { getCollection } from './mongodb.js';
-import { isAppleAppExpired } from '../models/apple-app.js';
+import { getJson, putJson } from './kv.js';
 
+// KV-backed Apple app cache. Key shape: `apple:{appId}`.
+// KV's expirationTtl replaces Java/Mongo's manual `(now - millis) > cacheMillis`
+// check — expired keys are deleted, so a get() returning null is the cache miss.
 export function createAppleAppRepository(env, appCacheSeconds) {
-  function collection() {
-    return getCollection('apple_app', env);
+  function key(appId) {
+    return `apple:${appId}`;
   }
 
   async function get(appId) {
-    const c = await collection();
-    return c.findOne({ _id: appId });
+    return getJson(env, key(appId));
   }
 
   async function save(entry) {
-    const c = await collection();
-    await c.replaceOne({ _id: entry._id }, entry, { upsert: true });
+    await putJson(env, key(entry._id), entry, { expirationTtl: appCacheSeconds });
   }
 
   async function getCached(appId) {
-    const entry = await get(appId);
-    if (!entry) return null;
-    if (isAppleAppExpired(entry, Date.now(), appCacheSeconds * 1000)) return null;
-    return entry;
+    return get(appId);
   }
 
   return { get, save, getCached };

src/repository/google-app-repository.js

@@ -1,26 +1,23 @@
-import { getCollection } from './mongodb.js';
-import { isGoogleAppExpired } from '../models/google-app.js';
+import { getJson, putJson } from './kv.js';
 
+// KV-backed Google app cache. Key shape: `google:{appId}`.
+// KV's expirationTtl replaces Java/Mongo's manual `(now - millis) > cacheMillis`
+// check — expired keys are deleted, so a get() returning null is the cache miss.
 export function createGoogleAppRepository(env, appCacheSeconds) {
-  function collection() {
-    return getCollection('google_app', env);
+  function key(appId) {
+    return `google:${appId}`;
   }
 
   async function get(appId) {
-    const c = await collection();
-    return c.findOne({ _id: appId });
+    return getJson(env, key(appId));
   }
 
   async function save(entry) {
-    const c = await collection();
-    await c.replaceOne({ _id: entry._id }, entry, { upsert: true });
+    await putJson(env, key(entry._id), entry, { expirationTtl: appCacheSeconds });
   }
 
   async function getCached(appId) {
-    const entry = await get(appId);
-    if (!entry) return null;
-    if (isGoogleAppExpired(entry, Date.now(), appCacheSeconds * 1000)) return null;
-    return entry;
+    return get(appId);
   }
 
   return { get, save, getCached };

src/repository/group-repository.js

@@ -1,4 +1,4 @@
-import { getCollection } from './mongodb.js';
+import { del, getJson, putJson } from './kv.js';
 import {
   groupAddAppleApp,
   groupAddGoogleApp,
@@ -8,26 +8,24 @@ import {
   newGroup,
 } from '../models/group.js';
 
+// KV-backed per-group state. Key shape: `group:{chatId}`.
 export function createGroupRepository(env) {
-  function collection() {
-    return getCollection('group', env);
+  function key(groupId) {
+    return `group:${groupIdToKey(groupId)}`;
   }
 
   async function exists(groupId) {
-    const c = await collection();
-    const count = await c.countDocuments({ _id: groupIdToKey(groupId) });
-    return count > 0;
+    const doc = await getJson(env, key(groupId));
+    return doc !== null;
   }
 
   async function getGroup(groupId) {
-    const c = await collection();
-    const doc = await c.findOne({ _id: groupIdToKey(groupId) });
+    const doc = await getJson(env, key(groupId));
     return doc ?? newGroup(groupId);
   }
 
   async function saveGroup(group) {
-    const c = await collection();
-    await c.replaceOne({ _id: group._id }, group, { upsert: true });
+    await putJson(env, key(group._id), group);
   }
 
   async function initGroup(groupId) {
@@ -36,8 +34,7 @@ export function createGroupRepository(env) {
   }
 
   async function deleteGroup(groupId) {
-    const c = await collection();
-    await c.deleteOne({ _id: groupIdToKey(groupId) });
+    await del(env, key(groupId));
   }
 
   async function mutateAndSave(groupId, mutator) {

src/repository/kv.js

@@ -0,0 +1,38 @@
+// Thin wrapper around the Cloudflare KV binding `env.STORE_KV`.
+// All four logical collections live in one namespace, separated by key prefix:
+//   admin                       singleton
+//   group:{chatId}              per-group state
+//   apple:{appId}               cached Apple response (with KV TTL)
+//   google:{appId}              cached Google response (with KV TTL)
+
+// KV's minimum expirationTtl is 60s. Java/Mongo had no such floor; clamp here
+// so a low APP_CACHE_SECONDS override doesn't make put() reject.
+const KV_MIN_TTL_SECONDS = 60;
+
+export class KvUnavailable extends Error {
+  constructor() {
+    super('STORE_KV binding is missing — check wrangler.toml [[kv_namespaces]]');
+    this.name = 'KvUnavailable';
+  }
+}
+
+function binding(env) {
+  if (!env || !env.STORE_KV) throw new KvUnavailable();
+  return env.STORE_KV;
+}
+
+export async function getJson(env, key) {
+  return binding(env).get(key, 'json');
+}
+
+export async function putJson(env, key, value, opts = {}) {
+  const putOpts = { ...opts };
+  if (putOpts.expirationTtl != null) {
+    putOpts.expirationTtl = Math.max(KV_MIN_TTL_SECONDS, putOpts.expirationTtl);
+  }
+  await binding(env).put(key, JSON.stringify(value), putOpts);
+}
+
+export async function del(env, key) {
+  await binding(env).delete(key);
+}

src/repository/mongodb.js

@@ -1,41 +0,0 @@
-import { MongoClient } from 'mongodb';
-
-// Thrown when the driver fails to reach Atlas (e.g. paused cluster, network).
-// Command handlers catch this and reply with "Internal server error".
-export class MongoUnavailable extends Error {
-  constructor(cause) {
-    super(`MongoDB unavailable: ${cause.message}`);
-    this.name = 'MongoUnavailable';
-    this.cause = cause;
-  }
-}
-
-// Memoized per warm Worker isolate. Module-scope is per-isolate in Workers,
-// so this caches one Promise<{client, db}> for the isolate's lifetime.
-let memoized = null;
-
-export async function getMongo(env) {
-  if (memoized) return memoized;
-  memoized = (async () => {
-    try {
-      const client = new MongoClient(env.MONGODB_URI, {
-        serverSelectionTimeoutMS: 5000,
-        socketTimeoutMS: 10000,
-        appName: 'js-store-scraper-bot',
-      });
-      await client.connect();
-      // db() with no arg uses the database from the URI path.
-      const db = client.db();
-      return { client, db };
-    } catch (err) {
-      memoized = null; // allow retry on next request
-      throw new MongoUnavailable(err);
-    }
-  })();
-  return memoized;
-}
-
-export async function getCollection(name, env) {
-  const { db } = await getMongo(env);
-  return db.collection(name);
-}

src/repository/store.js

@@ -4,7 +4,7 @@ import { createAppleAppRepository } from './apple-app-repository.js';
 import { createGoogleAppRepository } from './google-app-repository.js';
 
 // Single binding point for all repositories. Threads `env` once so command
-// handlers don't need to know about the Worker `env` argument.
+// handlers don't need to know about the Worker `env` argument or the KV binding.
 export function createStore(env, appCacheSeconds) {
   return {
     admin: createAdminRepository(env),