Simple mode: `sai "<prompt>"` uses `default_prompt` from the global config.
Advanced mode: `sai prompt.yml "<prompt>"` uses a specific prompt file so you
can swap toolsets per request. Prefer advanced mode when you need specialized
tools (data, git, destructive) without changing your defaults.

Combine flags as needed:
- `--scope` to steer the model toward the right files.
- `--peek` to show sample data.
- `--explain` or `--confirm` for interactive review.
- `--unsafe` when you explicitly allow operators.
- `--analyze` after a run to review the last command before iterating.

Environment variables (`SAI_*`) override AI config, which is handy for switching
providers or models per shell session. Ensure required tools are on PATH or use
absolute paths in tool names for clarity.
