Expressions

Template syntax

Expressions are embedded in ${{ }} within any template string:

prompt: "Hello ${{ inputs.name }}, iteration ${{ run.iteration }}"

Strings without ${{ }} are literal values.

Expression roots

Root	Scope	Description
inputs	Always	Workflow input parameters
steps	Always	Results from previous steps in scope
env	Always	Environment variables
run	Inside loops	Loop iteration context

Path access

Dot notation traverses objects and arrays:

inputs.name                    → input value
inputs.config.timeout          → nested field
steps.review.result            → full step result
steps.judge.result.count       → field in structured output
steps.list.result.0.name       → array index access
env.CI                         → environment variable
run.iteration                  → loop counter (1-based)

Operators

Operator	Example
== !=	steps.x.result == 'ok'
> >= < <=	steps.x.result.count > 0
&& ||	a && b
!	!steps.x.result.passed

Functions

Function	Description	Example
format(fmt, ...)	String formatting	format('{0}:{1}', a, b)
toJSON(value)	JSON stringification	toJSON(steps.data.result)
join(array, delim)	Join array	join(steps.x.result.tags, ', ')
len(value)	Count string chars, array items, or object keys	len(steps.review.result.findings)

Literals

null, true, false, numbers (42, 3.14), strings ('single quoted')