Function invocation_trigger_matches 

pub fn invocation_trigger_matches(
    haystack_lower: &str,
    trigger_lower: &str,
) -> bool

Reference implementation of the Tool::invocation_triggers matching contract: true when trigger occurs in haystack at a word boundary. Both are compared case-insensitively; the caller passes an already-lowercased haystack and a lowercased trigger. A boundary is the start/end of the string or any non-alphanumeric character (Unicode-aware), so a trigger matches only as a whole word or phrase (dev misses inside device, send this to hits inside please send this to marta). Boundaries and retry advancement are character-based, so multibyte trigger or haystack text is handled without panics or misclassification. Empty triggers never match.