modes/

One file per workflow, modes/<workflow>.yml, holding the default mode and overrides. Your workflow YAML is never touched.

defaultMode: mock

jobs:
  # A bare mode applies to the whole job
  lint: skip
  # Or override individual steps inside a job
  build:
    steps:
      "0": live
      "2": live

# Flat form: step keys are <jobId>.<stepIndex>
steps:
  deploy.1: mock

Key	Description
defaultMode	skip, mock, or live. Applies to every step without a more specific override. Falls back to mock when unset.
jobs.<jobId>	Either a bare mode for the whole job, or an object with a steps map of step index to mode.
steps.<jobId>.<stepIndex>	Flat per-step override. Step indices are zero-based.

Precedence: per-step override, then per-job, then the workflow default, then mock. The CLI flag --default-mode replaces the default for one run without editing the file.

The desktop app edits this file through the mode buttons on the workflow editor and DAG canvas; the modes file viewer shows the same data with inline toggles.