// model-attribution: turn a raw model id into a short, friendly label for the
// per-message model chip (e.g. "claude-sonnet-4-6" → "Sonnet 4.6",
// "qwen3.6-35b-a3b-mxfp4" → "Qwen3.6 35B"). Strips provider prefixes and maps
// the common families; falls back to the cleaned id so unknown models still
// read. Returns null for empty/absent input so the caller can skip the chip.
export function shortenModelName(model: string | null | undefined): string | null {
  if (!model) return null;
  let m = model.trim();
  if (!m) return null;

  // opencode / provider-prefixed ids: "llama-swap/qwen…", "anthropic/claude…".
  const slash = m.lastIndexOf('/');
  if (slash >= 0) m = m.slice(slash + 1);

  // claude-{opus,sonnet,haiku}-X-Y[-date] → "Opus X.Y".
  const claude = /^claude-(opus|sonnet|haiku)-(\d+)-(\d+)/i.exec(m);
  if (claude) {
    const tier = claude[1]!.charAt(0).toUpperCase() + claude[1]!.slice(1).toLowerCase();
    return `${tier} ${claude[2]}.${claude[3]}`;
  }

  // qwen3.6-35b-a3b-… → "Qwen3.6 35B".
  const qwen = /^qwen([\d.]+)-(\d+)b/i.exec(m);
  if (qwen) return `Qwen${qwen[1]} ${qwen[2]}B`;

  // gpt-4o, gpt-5-… → "GPT-4o" / "GPT-5".
  const gpt = /^gpt-([\w.-]+)/i.exec(m);
  if (gpt) return `GPT-${gpt[1]}`;

  // Fallback: keep the id readable, cap the length for the chip.
  return m.length > 26 ? `${m.slice(0, 25)}…` : m;
}