Choose workers; preserve the lead

Helpers live in ../crack/scripts/. Keep the user's existing model/provider choices. Installing skills alone does not configure workers or change the lead.

1. Run node ../crack/scripts/setup.mjs scan with the session's home/profile. Show relevant eligible models, efforts, image support, context, and exclusions. Catalog presence is not account access or a working provider route. Do not rank capabilities the catalog does not establish or invent prices.
2. Read an existing crack.toml before proposing changes. Start with one builder chosen by the user. Additional roles can map to implementation, ui, review, research, or tests with a tasks array. These are user preferences, not demonstrated model strengths. Set the exact model and a supported effort; keep fallback optional. Never change the selected lead to make setup pass.
3. Write a draft in a task-owned directory. Preview with node ../crack/scripts/setup.mjs plan --roles DRAFT and show the concrete model/effort and file changes. Apply the agreed configuration with node ../crack/scripts/setup.mjs apply --roles DRAFT. If the specific model choices or global writes aren't yet authorized, obtain that decision after producing the preview. Don't repeat approval already given for those choices.
4. Return the receipt path and explain that a fresh client session must load the generated native roles. Run doctor.mjs; then use a real authorized task to verify child metadata. No paid installation smoke test is needed.

Draft shape (replace the model with an exact eligible ID):

schema_version = 1
[roles.builder]
model = "MODEL_FROM_SCAN"
writes = true
tasks = ["implementation", "tests"]
brief = "Implements the scoped task and verifies it for lead review."