Built-ins Overview

The full built-in power map in Downcity, including public SDK powers and platform-managed infrastructure powers

The current built-in power capabilities in code include:

skill
web
sound
messenger
schedule
task
memory
shell

Package imports

Each SDK-facing built-in has an isolated package subpath:

Built-in	Import path
`messenger`	`@downcity/powers/messenger`
`memory`	`@downcity/powers/memory`
`skill`	`@downcity/powers/skill`
`task`	`@downcity/powers/task`
`web`	`@downcity/powers/web`

image and sound are City capabilities rather than @downcity/powers subpaths, so they are configured through City instead of imported from a package subpath.

Use create_builtin_power_registrations() for the default collection, or import and instantiate only the Powers required by a City. Selection happens at City level, not per Agent.

Two groups matter

Public SDK-facing built-ins

These are the ones most developers are likely to read first:

skill
web
sound
messenger

sound requires the FED model catalog plus ASR and TTS functions through its constructor. Built-in powers are assembled explicitly from their individual package subpaths.

These are the clearest examples for:

action powers
hook or resolve powers
system text powers
lifecycle powers that normal SDK users may still understand directly

Platform-managed or infrastructure built-ins

These are also built-ins in code, but they are more platform-oriented:

schedule
task
memory
shell

These powers are usually read to understand how the platform is assembled, not because every SDK user should manually attach them to a local Agent.

How to read this section

If you want user-facing capability powers, start with skill, web, sound, and messenger
If you want platform rule layers, read the built-in authorization capability in messenger
If you want infrastructure patterns, read schedule, task, memory, and shell

Responsibility map

Power	Main role	Shape
`skill`	skill discovery, installation guidance, and content loading	action + system
`web`	web methodology injection and dependency preparation	action + system
`sound`	FED speech-model discovery, ASR, TTS, and inbound auto-transcription	action + pipeline + system
`messenger`	channel runtime, queue worker, messenger authorization, and role resolution	lifecycle + actions + hooks + resolves + system
`schedule`	power action scheduling infrastructure	lifecycle-only infrastructure
`task`	task scheduler and cron execution	lifecycle + actions + system
`memory`	provider-neutral long-term memory and recall	lifecycle + actions + system
`shell`	shell session runtime	lifecycle + actions

Important distinction

Do not read “built-in” as “all of these are equally public.”

Some built-ins are best understood as:

public capability powers
platform integration powers
infrastructure powers

That distinction is one of the reasons the power concept docs stay in Agent SDK Docs, while concrete power guides live here.