Claude-skill-registry code-investigation

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.

install

source · Clone the upstream repo

git clone https://github.com/majiayu000/claude-skill-registry

Claude Code · Install into ~/.claude/skills/

T=$(mktemp -d) && git clone --depth=1 https://github.com/majiayu000/claude-skill-registry "$T" && mkdir -p ~/.claude/skills && cp -r "$T/skills/data/code-investigation" ~/.claude/skills/majiayu000-claude-skill-registry-code-investigation && rm -rf "$T"

manifest: skills/data/code-investigation/SKILL.md

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

Find RPC in
```
schema/proto/rapid/**/api.proto
```

Find handler in

internal/infrastructure/grpc/internal/handler/{actor}/

Find interactor in
```
internal/usecase/*_impl.go
```

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

Find interface definition in
```
internal/domain/repository/
```
Find all implementations in
```
internal/infrastructure/*/repository/
```
Find all callers in
```
internal/usecase/
```
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)