Custom ACP
Add your own ACP-compatible CLIs to Happier by defining selectable custom ACP backends.
Custom ACP is Happier's generic provider family for any CLI that speaks the Agent Client Protocol (ACP).
Use it when Happier does not ship a dedicated built-in provider for the tool you want to run, or when you want to add your own backend choices on top of an ACP-compatible CLI.
What Custom ACP gives you
Custom ACP lets you define custom ACP backends.
Each custom ACP backend is both:
- the launcher definition for an ACP-compatible CLI
- the user-facing backend choice you select throughout Happier
Where to find it
Open:
- Settings
- AI provider settings
- Custom ACP
From there, Happier links to the shared ACP catalog screens where you can manage:
- ACP Backends
- Custom backends
You can also open the catalog directly from Settings → ACP Backends.
What a custom ACP backend contains
A custom ACP backend stores the information Happier needs to launch and reason about one backend choice.
Typical backend details include:
- id / name / title
- description
- command
- arguments
- environment variables
- transport profile
- auth metadata
- capability hints
- optional default mode
- optional default model
How Custom ACP appears in Happier
Configured ACP backends are first-class backend choices.
They can appear in:
- the new session backend picker
- profile compatibility and backend-specific defaults
- permissions defaults
- session launcher flows such as review, plan, and delegate
- backend-aware guidance and suggestion surfaces
This means you do not need to remember raw commands once the backend is configured.
Models, modes, and defaults
When the underlying ACP CLI supports it, Happier can probe a configured backend directly for:
- available models
- available modes
- other ACP capability hints
That lets different custom backends behave as distinct backend choices, even when they happen to launch the same CLI with different args or env.
Authentication
Custom ACP does not imply one single provider-level auth system.
Instead, auth/readiness metadata lives with each ACP backend definition. Depending on the CLI, a backend can describe:
- a login command
- status-check support
- machine-login hints
- documentation links
Some ACP CLIs support safe non-interactive status detection. Others are effectively manual-only.
See Provider authentication for the general model.
Custom ACP vs built-in providers
Use a built-in provider when Happier already ships a dedicated integration for that tool.
Use Custom ACP when:
- you are adding a different ACP-compatible CLI
- you want your own backend choice with custom launcher/auth/defaults metadata
- you want a generic ACP integration rather than a bespoke provider page
For example:
- use Kiro for Happier's built-in Kiro integration
- use Custom ACP for arbitrary user-defined ACP backends
Common use cases
One CLI, multiple backend choices
If you want multiple variants of the same CLI, create multiple custom ACP backends.
That is the recommended pattern when:
- the command is mostly the same
- the auth setup is the same
- the args, env, or defaults differ per role
Team-internal ACP agent
Use Custom ACP when your team has an internal ACP-compatible CLI that Happier does not know about out of the box.
Development and testing
Use Custom ACP when you want to point Happier at a local ACP stub or test harness during development.