What problem does it solve? Authoring CEL expressions for Fianu policy criteria and indexes fails with parser errors (errVarType, HTTP 400) when the required type-cast grammar is missing, and the operator vocabulary is not obvious from the API alone. ## Core Features & Use Cases - Cast grammar reference: Documents the mandatory $asset.<field>.(<type>) form with string, list_string, int64, and bool casts, including correct cast placement before string-method calls. - Operator vocabulary: Covers equals, contains, startsWith, matches, in, exists, and their negations, plus valueless exists/not_exists operators and date comparison semantics. - Multi-clause scoping: Explains combining expressions with combineWith AND/OR and the field-name differences between index expressions[].source and policy criteria expression fields. - Use Case: You need a policy variation that applies only to production repositories owned by a specific team. Use this Skill to write $asset.labels.(string).contains("tier:prod") combined with an owner startsWith clause under combineWith AND. ## Quick Start Write a CEL expression that scopes a Fianu policy to assets whose path starts with services/ and whose labels contain tier:prod.
