Atmos Steps

Atmos steps are the shared execution DSL used by workflows, custom commands, hooks (kind: step), and cast recordings. When a task involves steps:, step type, working_directory, env, output, retries, or hook with: payloads, use this skill together with the surface-specific skill (atmos-workflows, atmos-custom-commands, or atmos-hooks).

Core Model

A step is a typed action with native fields. Do not treat steps as a place to write shell scripts by default. Prefer the Atmos field that expresses the operation directly:

Use working_directory instead of cd for real execution. A type: simulate child of a mode: steps cast may display cd <directory> to narrate a directory transition, but it never changes the working directory of later real steps.
Use env maps instead of inline FOO=bar command or export.
Use output: none instead of redirecting to /dev/null.
Use type: script instead of heredoc shell snippets like python3 - <<'PY'.
Use type: workdir with source and reset instead of mkdir, rm -rf, and cp.
Use type: atmos for Atmos commands instead of shelling out to atmos ... when the surface supports typed steps.
Use Atmos Terraform/OpenTofu rc configuration instead of hand-managing temporary .terraformrc or .tofurc files.

Shell is still valid for real shell work, but it should be a conscious fallback when no native step type or field expresses the intent.

Where Steps Run

Step fields are shared, but defaults differ by surface:

Workflows default command steps to type: atmos.
Custom command string steps historically behave like shell commands; use structured step objects when you need typed behavior.
Hooks use an envelope plus with:. For kind: step, the hook's type selects the step type, while with: contains the step-specific fields.
Cast steps can run nested steps and record their terminal output.

Always load the surface-specific skill for invocation rules, path anchoring, and template context.

Common Fields

Most typed steps can use these fields when the step type supports them:

steps:
  - name: validate
    type: script
    interpreter: python3
    working_directory: !repo-root .
    env:
      ATMOS_LOGS_LEVEL: warn
    output: none
    retry:
      max_attempts: 3
      delay: 2s
    script: |
      print("ok")

Important shared fields:

name: Stable step id for logs, dependencies, outputs, and resume behavior.
type: Registered step handler; the canonical catalog below is the source for authored YAML.
command: Command text for command-running steps.
script and interpreter: Inline script body and runtime for type: script.
working_directory: Directory for the subprocess or script.
env: Map of environment variables layered onto the step.
output: Output mode: raw, log, viewport, or none.
retry: Retry policy around the whole step.
identity: Atmos identity used when the step runs.
when: Declarative condition for whether the step runs.
needs: Dependency names for concurrent control steps.
timeout: Duration limit for supported steps.
tty and interactive: Terminal handoff for commands that need it.

Step Types

Use the docs at website/docs/workflows/workflows/workflow/steps/type.mdx and the type-specific files under website/docs/workflows/workflows/workflow/steps/type/ as the canonical reference. Current canonical step types include:

Command and integration: atmos, shell, script, exec, container, emulator, http, archive, require, workdir, cast, store.
Orchestration: parallel, matrix, wait, wait-all, cancel.
Interactive: input, confirm, choose, filter, file, write.
UI and output: toast, markdown, spin, table, pager, format, join, style, log, junit, hint, alert, say, title, clear, linebreak, stage, sleep, env, exit.

Use webhook only as the http alias and assert only as the require alias; document and configure the canonical names unless compatibility requires an alias.

If code and docs disagree, inspect the registered step handlers under pkg/runner/step/ and schema constants in pkg/schema/task.go.

Environment

Prefer map syntax:

env:
  PATH: '{{ env "PWD" }}/../../.context/bin:{{ env "PATH" }}'
  ATMOS_LOGS_LEVEL: warn

For custom commands, command-level env supports the same map style. Use template expressions such as {{ env "PATH" }} or .Env where supported. Use valueCommand only when the value genuinely must come from a command's stdout; do not move shell string building into valueCommand.

Working Directory

Use working_directory at the narrowest useful scope:

steps:
  - name: docs
    type: shell
    working_directory: !repo-root .
    command: npm run docs:build

Do not use --chdir or cd for real workflow, custom-command, or step execution when working_directory can express the same thing. In a mode: steps cast, a display-only type: simulate cd <directory> is the exception: use it to keep the recorded story coherent, and still configure working_directory on every real step. Relative paths must be checked against the surface's base path rules.

Working-directory resolution is not one rule — it differs by surface, and getting this wrong silently anchors relative fields (source, destination, path, files, context, ...) to the wrong directory instead of erroring:

Surface	Relative `working_directory` resolves against
Custom command's own `working_directory:` (command- or step-level)	Atmos `base_path` — always, whether or not the value starts with `./`
A workflow's own `working_directory:` (the workflow-level default), or a `type: shell`/`exec`/`atmos` step's `working_directory:`	Atmos `base_path` — always, whether or not the value starts with `./`
An extended/registered step type (`archive`, `file`, `junit`, `workdir`, `container`, ...) with its own step-level `working_directory:`	The current working directory — always, whether or not the value starts with `./`
`kind: step`/`kind: steps` hook	The component's own working directory for a bare value or when unset; the current working directory for a dot-prefixed value (`.`, `..`, `./x`, `../x`) — see `atmos-hooks` for the full Dot/Bare rule

A workflow-level working_directory: default still reaches extended step types that leave their own working_directory: unset — it falls back to the same base_path-anchored resolution the workflow-level default already gets for shell/exec/atmos steps.

After working_directory is resolved, relative handler fields such as source, destination, path, files, and context resolve against that directory. For container builds, Dockerfile resolves relative to the resolved context, not directly to working_directory.

Output

Use output modes instead of pipe redirection:

steps:
  - name: prepare
    type: atmos
    command: terraform generate varfile vpc -s dev
    output: none

output: none is for quiet setup. raw preserves command output, log routes through Atmos logging, and viewport is for richer terminal display.

Script Steps

Use type: script for inline scripts:

steps:
  - name: validate-cast
    type: script
    interpreter: python3
    script: |
      from pathlib import Path

      text = Path("website/static/casts/examples/sops-secrets.cast").read_text()
      if "All proofs passed" not in text:
          raise SystemExit("cast validation failed")

Do not put command on a script step. The schema requires interpreter and script.

Workdir Steps

Use type: workdir for repeatable scratch directories:

steps:
  - name: stage-fixtures
    type: workdir
    path: .context/casts/demo
    source: demo/casts/fixtures
    reset: true

This replaces shell sequences that create, delete, and copy directories.

Hooks

For hooks, the hook envelope controls lifecycle behavior and with: is the step payload. A scaffold template may use this bridge too, but only with kind: step or kind: steps and its two generation events:

hooks:
  notify:
    kind: step
    type: http
    events: [after.terraform.apply]
    on_failure: warn
    retry:
      max_attempts: 3
    with:
      url: https://example.com/hook
      method: POST

Use atmos-hooks for hook events, outcome conditions, on_failure, and preflight behavior.

Verification

When changing step YAML, verify the user-facing command from the directory where users actually run Atmos. Prefer working_directory fields in YAML and command tool workdir settings in tests over shell cd or --chdir.

SKILL.md