crab freeze and unfreeze

Freeze workflow stages so crab run skips them until they are explicitly unfrozen.

Freezing changes the selected stage declaration in its workflow YAML. It does not delete cached results or edit the stage command. Use it when an output is accepted for now and downstream work should continue without executing that stage again. Unfreeze the stage when its command or inputs should participate in normal invalidation and execution.

Synopsis

crab freeze [OPTIONS] <TARGET>...
crab unfreeze [OPTIONS] <TARGET>...

<TARGET> values are stage targets from crab.yaml.

crab freeze prepare-data train
crab unfreeze train
crab freeze --json prepare-data

Behavior and verification

Each target must resolve to a declared workflow stage. Crab discovers workflow files recursively, updates the file that owns the stage, and reports whether the declaration changed. Repeating crab freeze on an already frozen stage is therefore safe: its structured result reports changed: false.

Review the YAML change before committing it:

git diff -- crab.yaml '*.workflow.yaml'
crab run prepare-data train

The diff should show frozen: true for frozen stages or remove the frozen state after crab unfreeze. A subsequent run skips a frozen target but can continue through the rest of the selected graph. Commit the workflow-file change when the frozen state should be shared with collaborators and CI.