ブレインストーミング（アイデアから承認済みの設計へ）

Classification: architectural. This is a new project with no existing code, so there's no flow to treat as a bounded change. I'll follow the full path: questions, approaches, design, written spec, then an implementation plan. I won't write code, scaffold or install anything until you've approved the spec and the plan. If you'd rather have something lighter, tell me and I'll adjust.

Project context: you said the folder is empty and it isn't a git repo, so there's nothing to read or follow. I'll set up git when I write the spec, because the process commits the spec.

My understanding so far

What you said:

• You want a small command-line tool.
• It converts CSV files to JSON.
• It's a brand-new project.

What I'm assuming (please correct any of these):

• It's a single-purpose tool: one CSV in, JSON out, with no server or UI.
• The default output is an array of objects, using the header row as keys.
• It reads a file path or stdin and writes to stdout or a file.
• Success means you can run it on a normal CSV and get correct, valid JSON, including quoted fields and embedded commas.

I don't yet know why you need it or who will use it, and that decides most of the design. So here is my first question:

What will this tool mainly be used for?

• A. Personal or ad-hoc use. You run it by hand on files and want it quick and simple.
• B. Part of scripts or pipelines. It needs stdin/stdout support, predictable exit codes and machine-friendly behavior.
• C. Something you'll share or publish as a package for others.
• D. Something else. Tell me what.

I'll ask about language, type handling (for example, whether "42" becomes a number) and large-file handling after your answer, one question at a time.