FlameInTheDark/logic-expression-guide

Use this skill when the task is about expressions in logic nodes.

Use Expr Semantics

• logic:condition and expression-based logic:switch branches use expr-lang style expressions.
• The expression must evaluate to a boolean.
• input is available as the full payload.
• Top-level input keys are also exposed directly.

Write Typical Expressions

input.status == "ready"
retries > 3
input.response.status_code >= 200 && input.response.status_code < 300
input.cluster == "prod" && input.enabled == true

Keep Expressions Different From Templates

• Use plain expr syntax in condition fields.
• Do not wrap the whole expression in {{ ... }}.
• Templating runs before expression evaluation only when the field supports templating, but the normal condition pattern is plain expr syntax.

Prefer Clear Checks

• Compare explicit fields instead of serializing whole objects.
• Use input.<field> when the source should stay obvious.
• Keep branch logic short and readable.

Avoid Common Mistakes

• Do not return a string or number when a boolean is required.
• Do not use Lua syntax inside expr fields.
• Do not mix template braces into a normal condition expression.