Function detect_normalization_failure 

pub fn detect_normalization_failure(
    content: &str,
) -> Option<NormalizationPattern>

Inspect content and return the first NormalizationPattern detected, or None if the content looks well-formed.

Detection priority:

1. EmptyAction — content is blank, or Action: with nothing after it.
2. MalformedToolCall — Action: / tool_call present but JSON is broken.
3. NarratedToolUse — model described intent without an Action: block.