structuring-an-action

Use when laying out a new GitHub Action repository on the @effected suite, deciding where a piece of code belongs (an entry point, a step, a shared service, a shim), or reviewing an existing action's file structure against the canonical shape. Also use when: action repo structure, src layout, where does this code go, steps vs services, program.ts, layers/app.ts, test placement, uncollected test file, vitest.setup, action.yml single source, scaffolding a new action, dependency honesty, shim register