Agent frameworks write down what a step may touch in their own plans. gantry adapt turns such a plan into the verify.yaml for that step and prints the cage scope for the session that runs it:
gantry adapt plans/format-greeting.md --from lights-on --step 1.1 --check "node --test" --out verify.yaml
# adapt: cage scope: gantry cage --allow-only src/format-greeting.js --allow-only src/format-greeting.test.js -- <agent>The files the step lists become allowed_paths. The run’s own machinery (.claude, .gitagent), lockfiles, plans/ and verify.yaml are always forbidden_paths. A step that is expected to split a file gets --allow-new <dir>, so new files there pass and files anywhere else still fail. Commit the contract before the step runs. A plan without the notation, or a step without its three file lists, stops with GXT_ADAPT_PLAN_INVALID (exit 2). The format supported so far is lights-on (lights-on-software-factory: #### Step <n>: with Files to create, Files to modify, Files to delete). The library exports the same function as adaptPlan.
Then run the step inside the scope adapt printed, and verify the result against the committed contract. Verify a change without missions explains the contract and the run.
Design notes: ADR-0059 plan adapters.