Expressions

The expression language is CEL. An expression is allowed in condition of a condition node, in when of a switch node, and in any value whose key carries the .$ suffix in arguments, outputs and variables.

"outputs": {
  "value": "n",
  "attempts.$": "0",
  "greeting.$": "'hello ' + string(vars.user_name)"
}

Frame variables are addressed through the vars namespace (vars.n). A name that is not an ASCII identifier is addressed by index: vars['итог'].

A key with the .$ suffix in outputs names a variable rather than a stage field, so a single node can introduce any number of pipeline variables.

Backend: common-expression-language (native), falling back to cel-python.

In the editor an expression is a field like any other. A condition node has one, and every argument has a switch between "variable" and "expression".