code-investigation

name	code-investigation
description	Efficient codebase investigation for rapid-go. Use when understanding existing code before modifications, tracing request flows from API to database, finding where functionality is implemented, or analyzing impact before changes. ALWAYS use before modifying existing code, fixing bugs, or adding features.

Code Investigation Guide

Quick Start

Proto (API contract) -> Handler -> Usecase -> Repository -> DB

Use this flow to trace any feature. Start from what you know.

Key Locations

What	Where
API contracts	schema/proto/rapid/{admin_api,public_api,debug_api}/v1/
Handlers	internal/infrastructure/grpc/internal/handler/{admin,public,debug}/
Usecases	internal/usecase/*_impl.go
Domain models	internal/domain/model/
Repository interfaces	internal/domain/repository/
Repository implementations	internal/infrastructure/{mysql,postgresql,spanner}/repository/
DI wiring	internal/infrastructure/dependency/dependency.go
Auth interceptors	internal/infrastructure/grpc/internal/interceptor/

Investigation Patterns

Find an API endpoint

# Find by HTTP path
grep "/admin/v1/tenants" schema/proto/rapid/

# Find by RPC name
grep "CreateTenant" internal/infrastructure/grpc/internal/handler/admin/

Trace request flow

1. Find RPC in schema/proto/rapid/**/api.proto
2. Find handler in internal/infrastructure/grpc/internal/handler/{actor}/
3. Find interactor in internal/usecase/*_impl.go
4. Find repository in internal/domain/repository/ (interface) and internal/infrastructure/*/repository/ (impl)

Find all usages of a type

# Find usages of a domain model
grep "model.Staff" internal/

# Find usages of a repository method
grep "staffRepository.Get" internal/usecase/

Check authorization logic

• Session extraction: internal/infrastructure/grpc/internal/interceptor/session_interceptor/
• Access control: internal/infrastructure/grpc/internal/interceptor/authorization_interceptor/
• Role checks in usecase: look for param.AdminRole.IsRoot() patterns

Impact analysis before changes

1. Find interface definition in internal/domain/repository/
2. Find all implementations in internal/infrastructure/*/repository/
3. Find all callers in internal/usecase/
4. Check mock generation: internal/domain/repository/mock/

Common Search Patterns

Goal	Search
Find entity by name	grep "type Staff struct" internal/domain/model/
Find error definition	grep "StaffNotFoundErr" internal/domain/errors/
Find input validation	grep "type AdminCreateStaff" internal/usecase/input/
Find marshaller	grep "StaffToModel|StaffToPb" internal/
Find DI registration	grep "AdminStaffInteractor" internal/infrastructure/dependency/

Tips

• Start from proto for API-related investigation
• Start from domain model for business logic investigation
• Check dependency.go to understand how components are wired
• Marshallers exist in two places: repository (DB<->domain) and handler (domain<->proto)