Function render_short 

pub fn render_short(d: &Diagnosis) -> String

Compact one-screen summary used by the diagnose subcommand.

Includes case, rule, severity (rank + provenance label only — the full rationale is left to render_report), likely cause, the pinned evidence list, and the reproduction command. Omits hypotheses, unknowns, next-steps, and the escalation note. The diagnose subcommand is the most-shown surface (first command in scripts/run_demo.sh), so the output is intentionally short.