/gitignore-gen

If $ARGUMENTS is provided, treat it as the stack specification (e.g., "node react", "python fastapi", "rust", "go terraform").

If $ARGUMENTS is empty, detect the stack by inspecting the working tree:

• Run ls -1 at the repo root and scan for indicator files: package.json, Cargo.toml, go.mod, pyproject.toml, requirements.txt, Gemfile, pom.xml, build.gradle, *.sln, Dockerfile, .terraform/, etc.
• Check for editor/IDE files: .vscode/, .idea/, *.xcodeproj
• Check for OS: detect macOS (.DS_Store risk) or Windows (Thumbs.db risk) from the environment

If a .gitignore already exists at the repo root, read it first. Add only rules that are missing — do not duplicate existing entries.

Generate the .gitignore content organized into labeled sections:

# === <Stack> ===
# === Editor / IDE ===
# === OS ===
# === Secrets & local config ===
# === Build output ===
# === Test artifacts ===

Rules for each section:

• Stack: language-specific build dirs, compiled artifacts, package caches, virtual envs, dependency dirs
• Editor/IDE: .vscode/ (keep .vscode/extensions.json and settings.json if team-shared — note this), .idea/, *.swp, *.swo, .DS_Store, Thumbs.db
• Secrets: .env, .env.* (except .env.example), *.pem, *.key, secrets.*, credentials.*
• Build output: dist/, build/, out/, target/, *.o, *.a, *.so, *.dll
• Test artifacts: coverage/, .nyc_output/, *.lcov, htmlcov/, .pytest_cache/, __snapshots__/ (only if not version-controlled intentionally)

After the content block, note any patterns that require team discussion before adding (e.g., whether to ignore .vscode/settings.json).

Do not write the file to disk. Output the full .gitignore content for the user to review and apply.