Use as the first pass on an unfamiliar codebase or ambiguous request, before /spec, /design, or /implement — "tôi mới vào dự án này", "tìm hiểu hệ thống trước khi làm feature X", "context nào đã có sẵn", or any request touching an existing system/module/feature you don't yet know enough about. Auto-detects the stack (frontend, mobile, backend, scripts). Also use when it's unclear whether a capability already exists before building it again. Do NOT use once the area is already understood, or for whole-system documentation (`/architecture`) or detailed requirements gathering (`/spec`).
