@molecule/api-cache

Auto-generated, AI-first package reference for the molecule.dev ecosystem. It is written to be read by coding agents as much as by people, and is generated from this package's source — edit src/index.ts JSDoc, not this file.

Provider-agnostic caching interface for molecule.dev.

Defines the CacheProvider interface for key-value caching with TTL, tags, batch operations, and cache-aside (getOrSet). Bond packages (Redis, Memcached, in-memory, etc.) implement this interface. Application code uses the convenience functions (get, set, del, has, getOrSet) which delegate to the bonded provider.

Quick Start

import { setProvider, get, set, getOrSet } from '@molecule/api-cache'
// Pick the bond by what's provisioned — in-memory needs nothing (safe default); swap to
// `@molecule/api-cache-redis` ONLY when a managed Redis exists (REDIS_URL is in the env).
import { createProvider } from '@molecule/api-cache-memory'

setProvider(createProvider())
await set('user:123', userData, { ttl: 3600 })
const cached = await get<UserData>('user:123')
const fresh = await getOrSet('user:456', () => fetchUser('456'), { ttl: 600 })

Type

core

Installation

npm install @molecule/api-cache @molecule/api-bond @molecule/api-i18n

API

Interfaces

CacheOptions

Cache entry options.

interface CacheOptions {
  /**
   * Time-to-live in seconds.
   */
  ttl?: number

  /**
   * Tags for cache invalidation.
   */
  tags?: string[]
}

CacheProvider

Cache provider interface.

All cache providers must implement this interface.

interface CacheProvider {
  /**
   * Gets a value from the cache.
   *
   * @param key - Cache key
   */
  get<T = unknown>(key: string): Promise<T | undefined>

  /**
   * Sets a value in the cache.
   *
   * @param key - Cache key
   * @param value - Value to cache
   * @param options - Cache options (ttl, tags)
   */
  set<T = unknown>(key: string, value: T, options?: CacheOptions): Promise<void>

  /**
   * Deletes a value from the cache.
   *
   * @param key - Cache key
   * @returns true if the key existed and was deleted
   */
  delete(key: string): Promise<boolean>

  /**
   * Checks if a key exists in the cache.
   *
   * @param key - Cache key
   */
  has(key: string): Promise<boolean>

  /**
   * Gets multiple values from the cache.
   *
   * @param keys - Array of cache keys
   */
  getMany?<T = unknown>(keys: string[]): Promise<Map<string, T>>

  /**
   * Sets multiple values in the cache.
   *
   * @param entries - Array of [key, value] pairs
   * @param options - Cache options applied to all entries
   */
  setMany?<T = unknown>(entries: Array<[string, T]>, options?: CacheOptions): Promise<void>

  /**
   * Deletes multiple values from the cache.
   *
   * @param keys - Array of cache keys
   */
  deleteMany?(keys: string[]): Promise<number>

  /**
   * Invalidates all cache entries with the given tag.
   *
   * @param tag - Tag to invalidate
   */
  invalidateTag?(tag: string): Promise<void>

  /**
   * Clears all cache entries.
   */
  clear?(): Promise<void>

  /**
   * Closes the cache connection.
   */
  close?(): Promise<void>

  /**
   * Gets or sets a value using a factory function.
   *
   * @param key - Cache key
   * @param factory - Function to generate the value if not cached
   * @param options - Cache options
   */
  getOrSet?<T = unknown>(key: string, factory: () => Promise<T>, options?: CacheOptions): Promise<T>
}

Functions

del(key)

Deletes a cached value by key.

function del(key: string): Promise<boolean>

• key — The cache key to delete.

Returns: true if the key existed and was deleted, false otherwise.

get(key)

Retrieves a cached value by key, or undefined if not found or expired.

function get(key: string): Promise<T | undefined>

• key — The cache key to look up.

Returns: The cached value cast to T, or undefined if not found.

getOrSet(key, factory, options)

Cache-aside helper: returns the cached value if it exists, otherwise calls the factory function, caches the result, and returns it. Uses the provider's native getOrSet if available, otherwise falls back to a get + set sequence.

function getOrSet(key: string, factory: () => Promise<T>, options?: CacheOptions): Promise<T>

• key — The cache key.
• factory — Async function that produces the value when cache misses.
• options — Optional TTL and tags for the cached entry.

Returns: The cached or freshly-computed value.

getProvider()

Retrieves the bonded cache provider, throwing if none is configured.

function getProvider(): CacheProvider

Returns: The bonded cache provider.

has(key)

Checks whether a key exists in the cache.

function has(key: string): Promise<boolean>

• key — The cache key to check.

Returns: true if the key exists in the cache.

hasProvider()

Checks whether a cache provider is currently bonded.

function hasProvider(): boolean

Returns: true if a cache provider is bonded.

set(key, value, options)

Stores a value in the cache under the given key, with optional TTL and tags.

function set(key: string, value: T, options?: CacheOptions): Promise<void>

• key — The cache key.
• value — The value to store.
• options — Optional TTL in seconds and tags for invalidation.

Returns: A promise that resolves when the value has been stored.

setProvider(provider)

Registers a cache provider as the active singleton. Called by bond packages during application startup.

function setProvider(provider: CacheProvider): void

• provider — The cache provider implementation to bond.

Available Providers

Provider	Package
Memcached	@molecule/api-cache-memcached
In-memory (no persistence)	@molecule/api-cache-memory
Redis	@molecule/api-cache-redis

Injection Notes

Requirements

Peer dependencies:

• @molecule/api-bond ^1.0.1
• @molecule/api-i18n ^1.0.1

Runtime Dependencies

• @molecule/api-bond

• @molecule/api-i18n

• Pick the provider by what is actually PROVISIONED (read this FIRST). The bond you setProvider() is the ONLY thing that decides whether a managed server is required. @molecule/api-cache-memory is in-process and needs NOTHING — use it whenever no managed cache is provisioned: a fresh sandbox, a single-process app, or when you are ADDING caching to an app that did not already use Redis/Memcached. Use -redis / -memcached ONLY when a managed instance actually exists — i.e. its connection URL is present in the environment (REDIS_URL, etc.). Wiring -redis with no REDIS_URL compiles and can even let a memory-backed TEST pass, but the RUNNING app's cache then fails to connect (localhost:6379 refused) — a green test hiding a broken runtime. If durable/shared caching is genuinely needed and none is provisioned, ASK the user to connect one; do not assume it is there. The cache is BEST-EFFORT and often SHARED across users — treat it accordingly:

• A per-user value MUST include the user id in its KEY (user:123:profile, not profile). A shared key for per-user data leaks one user's data to another — a real cross-user data breach, not just a bug.

• Never rely on the cache for correctness or authorization. It can be empty, evicted, or stale — re-check ownership on the real data, and make the getOrSet loader carry the SAME ownership scope as a normal query.

• Invalidate on write. After updating the underlying record, del() (or re-set()) its key, or reads keep serving stale data.

• undefined means "not cached" — you cannot cache undefined (cache null instead). get() returns undefined for a miss, so a getOrSet factory that resolves to undefined is never treated as cached and will re-run on EVERY call.

• getOrSet does not lock: concurrent misses on the same key each run the factory (last write wins). Fine for idempotent loaders; don't put side-effecting work in one.

• Don't cache a raw secret; cache derived, non-sensitive data.

• clear() must be scoped to the bonded provider's own namespace, never a shared store. A conformant CacheProvider.clear() implementation removes ONLY keys it created (its keyPrefix/namespace) — it must NEVER issue a database-wide flush (Redis FLUSHDB/FLUSHALL, Memcached flush_all) that would also wipe sessions, queues, rate limiters, or another app's data sharing the same store. See @molecule/api-cache-redis (SCAN + batched UNLINK by keyPrefix) and @molecule/api-cache-memcached (namespace versioning, since Memcached has no key-enumeration command to scope a delete) for the two canonical strategies — implement whichever fits a new provider's capabilities, but never the raw flush.

E2E Tests

Integration checklist — exercise the REAL behavior end-to-end (drive the app action that reads/writes this cache in the live preview, no mocks), adapt each item to this app's actual screens/flows, and check every box off one by one. A box you can't check is an integration bug to fix — not a skip:

• getOrSet(key, factory, options) computes ONCE on a miss and serves the cached copy afterward: drive the same screen/endpoint twice within CacheOptions.ttl and confirm the expensive factory (DB/upstream call) runs only on the FIRST load — the second read returns the cached value without re-running it.
• set(key, value) then get<T>(key) round-trips the same value back into the app (the cached data renders identically to the source data).
• Deletion reflects a miss: after delete(key), has(key) is false and get(key) returns undefined, so the app recomputes fresh from source instead of serving the removed entry.
• TTL expiry refetches: once CacheOptions.ttl seconds elapse, the next read recomputes fresh data — a stale value is NEVER served past its TTL.
• A write that changes the underlying record invalidates its key (via delete() or a re-set()) so the very next read reflects the change — the app never serves a stale cached copy after an update.
• AUTHORIZATION: a per-user or per-tenant value is cached under a key that INCLUDES the user/tenant id (user:123:profile, never a global profile). Load user A's data, then user B's — B must receive B's own data, never A's cached copy. A shared key for per-user data is a cross-user data leak, not an optimization.
• A cache backend failure or miss DEGRADES to computing from source: the request still succeeds (getProvider()/get() unavailable falls back to the real query) rather than erroring the whole request.

Translations

Translation strings are provided by @molecule/api-locales-cache.