Create Component

Create a new Fx component following the modern (new-style) pattern with separate def/, fx/, and impl/ sub-packages.

IMPORTANT: NEVER use the legacy pattern (single-directory with fx.Provide directly). Always use the new-style pattern described below.

Instructions

1. Parse $ARGUMENTS to determine:

   • <bundle>/<component-name>: e.g., core/remoteflags means bundle=core, component=remoteflags
   • --team <team-name>: optional team ownership tag (default: ask the user)
   • --with-params: include a Params struct in the def package
   • --with-lifecycle: include compdef.Lifecycle in the Requires struct
   • --with-mock: also generate a mock/ sub-package

2. Ask the user (if not provided via arguments):

   • What is the component's interface? (what methods should it expose?)
   • Which team owns it? (for the // team: comment)
   • Does it need lifecycle hooks (start/stop)?
   • Does it need a Params struct?
   • What are its dependencies (other components it requires)?

3. Read reference examples before writing any code. Find a recent component under comp/ using the def/fx/impl pattern (e.g. comp/core/remoteagentregistry/). Read:

   • def/component.go — interface definition with // team: comment
   • fx/fx.go — Module() with fxutil.ProvideComponentConstructor
   • impl/<name>.go — Requires/Provides structs, NewComponent constructor

4. Create the directory structure under comp/<bundle>/<component>/:

   comp/<bundle>/<component>/
   ├── def/
   │   ├── go.mod
   │   ├── component.go     # Interface definition + team tag
   │   └── params.go        # (optional) Params struct
   ├── fx/
   │   ├── go.mod
   │   └── fx.go            # Module() function
   └── impl/
       ├── go.mod
       └── <component>.go   # Requires, Provides, NewComponent()
   

5. Create each file following the patterns from the reference. Key rules:

   • def/component.go: Package name = component name, include // team: comment, only interfaces
   • fx/fx.go: Use fxutil.ProvideComponentConstructor (NEVER raw fx.Provide), returns fxutil.Module
   • impl/<component>.go: Plain Go constructor func NewComponent(deps Requires) (Provides, error), no fx.In/fx.Out/compdef.In/compdef.Out embedding in Requires/Provides, unexported implementation type
   • go.mod files: Use v0.0.0 for inter-module dependencies, match Go version from root go.mod

6. Register the modules in modules.yml — add entries for def, fx, and impl (use default or used_by_otel: true).

7. Run dda inv create-module --path=comp/<bundle>/<component>/def (and for fx, impl) or manually add to modules.yml and run dda inv tidy.

8. Wire into a bundle if appropriate — add the component's Module() to the relevant comp/<bundle>/bundle.go.

9. Validate:

   dda inv lint-components lint-fxutil-oneshot-test github.lint-codeowner
   

   Fix any errors and re-run until clean.

Critical Rules (New-Style vs Legacy)

DO: def/fx/impl sub-packages, fxutil.ProvideComponentConstructor, plain Go constructor, plain Requires/Provides structs, thin def package.

DON'T: Single directory, fx.Provide(newComponent), fx.In/fx.Out embedding, implementation in def package.

Usage

• /create-component core/myfeature --team agent-runtimes --with-lifecycle
• /create-component metadata/hostinfo --team agent-metrics --with-params