Function diagnostic_is_user_visible 

pub fn diagnostic_is_user_visible(style: CommunicationStyle, code: &str) -> bool

Whether a diagnostic earns a main-transcript row under style.

Contract: persistence is never gated by this — callers persist the canonical event first and consult this only at paint time. Unknown codes fail open to visible; only the classified routine codes above (plus tool.command_failed under Quiet) go silent. tool.policy_denied, tool.cancelled, provider.retry_stopped, billing, planning, MCP, and runtime.* incidents stay visible in every style.