Decorators catalog

Titan and its ecosystem ship a lot of decorators. This page is the single-source-of-truth lookup: what each decorator does, which package to import it from, and which decorators share a name across packages (so you don't accidentally import the wrong one).

Every entry below is checked against the packages' real exports by a script, not by hand — a hand check is true on the day it is made and decays silently afterwards:

node internal/website/scripts/check-titan-inventories.mjs .

It exits non-zero if this page names a decorator no package exports, or if the set the root re-exports stops being exactly the nine listed above.

Quick lookup by purpose

You want to…	Reach for
Mark a class as DI-injectable	`@Injectable()` (core)
Expose a class as RPC service	`@Service('name@version')` (core)
Expose a method on the wire	`@Public()` (core)
Validate a method's args / return	`@Validate(schema)` (core)
Require authenticated caller	`@RequireAuth()` (titan-auth)
Skip auth for one method	`@Public()` (titan-auth — opts out of auth)
Memoise an idempotent method	`@Cacheable()` (titan-cache)
Throttle calls per key	`@RateLimit({ key, limit })` (titan-ratelimit)
Run at a cron schedule	`@Cron('0 * * * ')` (titan-scheduler)*
Run on an interval	`@Interval(60_000)` (titan-scheduler)
Subscribe to a typed event	`@OnEvent('user.created')` (titan-events)
Auto-emit an event from a method	`@EmitEvent({ event: 'user.created' })` (titan-events)
Wrap a method in a distributed lock	`@WithDistributedLock(key, ttl)` (titan-lock)
Instrument a method with RPC counters + latency	`@Metrics(metricName?)` (titan-metrics)
Define a worker process class	`@Process()` (titan-pm)
Define a supervised hierarchy	`@Supervisor()` + `@Child()` (titan-pm)
Bind a class to a config subtree	`@Configuration('cache')` (config built-in)
Read one config value	`@Config('cache.ttlMs', 60_000)` (config built-in)
Apply RLS to a repository	`@Policy(...)` + `@Allow`/`@Deny`/`@Filter` (titan-database)
Soft-delete a repository's rows	`@SoftDelete()` (titan-database)
Auto-add `created_at`/`updated_at`	`@Timestamps()` (titan-database)
Audit row changes	`@Audit()` (titan-database)

Core decorators

Built-in@omnitron-dev/titan

Ships inside @omnitron-dev/titan. No additional install required.

Imported from @omnitron-dev/titan/decorators, which exports all of them. The package root re-exports exactly nine — Service, Injectable, Inject, Optional, Singleton, Transient, Module, PostConstruct, PreDestroy — and nothing else, so @Public, @Validate, @Timeout, @RateLimit, @Cache and the rest below are not importable from @omnitron-dev/titan. Real code follows this: every one of the 52 @Public imports in the DAOS backends reads from '@omnitron-dev/titan/decorators'.

DI

Decorator	Targets	Effect
`@Injectable(opts?)`	class	Marks a class as a DI provider
`@Service(name)`	class	Marks a class as a Netron RPC service
`@Inject(token)`	parameter / property	Resolves a token from the container
`@Optional()`	parameter / property	Allow undefined if the token isn't registered
`@Global()`	class (on Module)	Makes the module's exports visible everywhere

RPC surface

Decorator	Targets	Effect
`@Public(opts?)`	method / property	Exposes the method on the wire
`@Contract(class)`	class	Binds a Zod-based input/output contract
`@Validate({input, output})`	method	Runs Zod schemas around the call
`@NoValidation()`	method	Opts out of class-level validation
`@WithValidationOptions(opts)`	class	Sets default validation behaviour for the class
`@ValidateInput(schema)`	method	Input-only validation
`@ValidateOutput(schema)`	method	Output-only validation

The core @Public() exposes; the titan-auth @Public() further marks the same method as auth-bypass. They compose: @Public() @RequireAuth() for an exposed-but-protected method is the common pattern.

Core also ships three lightweight composable annotations meant to sit alongside @Public() — they write metadata that transports / modules read, rather than implementing the behaviour themselves:

Decorator	Targets	Effect
`@Auth(opts?)`	method	Marks the method as requiring authentication
`@RateLimit(opts?)`	method	Attaches rate-limit metadata to the method
`@Cache(opts?)`	method	Attaches cache metadata to the method

These share names with the satellite-package decorators (titan-ratelimit.@RateLimit, titan-pm.@Cache, etc.). The core ones are bare metadata annotations; see the collision table below.

Lifecycle

Decorator	Targets	Effect
`@PostConstruct()`	method	Run after construction, before `onInit`
`@PreDestroy()`	method	Run during `onDestroy`

For full hooks (onInit, onStart, onStop, onDestroy) implement the interfaces instead — they're more discoverable than decorators. See Lifecycle reference.

Method utilities

Most utility decorators are method interceptors that compose freely with other decorators.

Decorator	Effect
`@Memoize`	Cache the result of a function in-memory by arg fingerprint
`@Retry({ attempts, delay })`	Retry on throw with linear delay
`@Retryable({...})`	More configurable retry (backoff curve, predicate)
`@Timeout({ ms })`	Reject if the method doesn't resolve within `ms`
`@Log({...})`	Log entry / exit / error
`@Monitor({...})`	Emit metric samples around the call
`@Deprecated({ message, version })`	Warn callers; metadata for tooling

The core @Timeout clashes with titan-scheduler.@Timeout — distinguish by import path (@omnitron-dev/titan/decorators vs @omnitron-dev/titan-scheduler).

Built-in module decorators

`config`

Built-in@omnitron-dev/titan/module/config

Ships inside @omnitron-dev/titan. No additional install required.

Decorator	Targets	Effect
`@Config(path, default?)`	property	Inject one config value at a dotted path
`@InjectConfig()`	property	Inject the whole `ConfigService`
`@Configuration(prefix?)`	class	Bind the class as a typed view of a config subtree
`@ConfigSchema(schema)`	class	Class-level Zod schema for the bound subtree
`@ConfigWatch(path)`	method	Method runs when the watched path changes
`@ConfigDefaults({...})`	class	Provide class-level defaults
`@ConfigProvider(name)`	class	Custom config provider class

@Configuration('cache')
class CacheConfig {
  @Config('ttlMs', 60_000)  ttlMs!: number;
  @Config('maxItems', 1024) maxItems!: number;
}

`logger`

Built-in@omnitron-dev/titan/module/logger

Ships inside @omnitron-dev/titan. No additional install required.

The logger module exports no decorators — instances are injected via token / interface (LOGGER_SERVICE_TOKEN, LOGGER_TOKEN). See logger.