Skill: Follow Goal

Run a long, durable objective across many turns toward a verifiable stop condition — instead of stopping after one normal exchange.

Requires session storage + artifact.

1. Persist — Save goal.md to session storage. This is the durable source of truth, readable across turns.
2. Mark as artifact — After saving, call setArtifacts to mark the file as a plan artifact so the user can see live goal state in the UI.

Do not write goal.md into the workspace. Do not rely on the artifact alone — artifacts are UI-only and cannot be read back by tools.

A goal has four parts. Capture all four before starting work:

1. Objective — what to achieve, in one sentence.
2. Stop condition — an observable, verifiable signal that "done" has been reached (a command exits 0, a file matches a spec, tests pass, parity check passes, etc.).
3. Validation — the concrete commands or artifacts that prove progress (test command, build command, lint, diff against reference, review or rubber duck skills).
4. Constraints — what NOT to change, scope boundaries, files/areas off-limits.

If any of these are missing or vague, ask the user before saving the goal. A goal without a verifiable stop condition is not a goal — it's a wish.