Installer etiquette: always offer scope (global vs project), link mode (symlink vs copy), and target agents

Problem

Running skills add <repo> --all non-interactively (piped output, scripts, or with -y) silently picks project scope in the current directory and symlink mode, with no surfaced choice. In TTY mode some prompts appear, but the scope prompt is skipped by -y's auto-detect ("project if in a project"), which surprises users who expected a global install — and nothing records a preference, so every future run re-guesses.

A user hitting this installed 37 skills into a random project folder and spent time debugging why their agent never saw them.

Request

Make these three choices first-class in every add/update flow:

1. Scope: global (user-level) vs project — always prompt in interactive mode; in non-interactive mode, fail with a clear message rather than silently defaulting, unless a flag (-g/-p) or a saved preference decides it.
2. Link mode: symlink (default today) vs direct copy (--copy) — prompt or persist a preference; symlinked skills confuse users who later edit or delete the store.
3. Target agents: the -a picker exists but is skippable/silent in non-interactive runs; never install to an unrequested agent set silently.

Suggested shape

• Persist answers (e.g. in skills-lock.json or a global config) as the new default, overridable per-run by flags.
• Non-interactive default without flags/persisted preference: error with guidance (specify -g or -p; --copy or symlink) instead of guessing. Loud > silent.
• Print a one-line post-install summary: scope, link mode, agents, paths written.

Verified on skills 1.7.0: -g, -a <agents>, --copy, -y all exist; the gap is that silence picks project+symlink+auto-detected agents with no summary.