// A phase-completion gate sometimes arrives with an artifact that is only a file
// *reference* (e.g. `{ kind: "phase", data: { file: "question.md" } }`) instead of
// the embedded content. The full content is already served by the session-documents
// endpoint, so we resolve the referenced file to the document key that carries it.

// Filename -> session-document key (see harness build_documents). Only markdown
// documents are listed: those we can render in full from the reference alone.
export const DOC_KEY_BY_FILE: Record<string, string> = {
  "question.md": "revised_question",
  "validation_report.md": "validation_report",
};

type ArtifactLike = { data?: unknown; content?: unknown; [k: string]: unknown };

/**
 * If the artifact is a bare file reference we can resolve, return the filename and
 * the session-document key holding its content. Returns null when the artifact
 * carries inline content (nothing to resolve) or points at an unmapped file.
 */
export function resolveFileArtifact(
  artifact: ArtifactLike
): { filename: string; docKey: string } | null {
  const payload = artifact.data ?? artifact.content;
  const rec =
    payload && typeof payload === "object" && !Array.isArray(payload)
      ? (payload as Record<string, unknown>)
      : null;
  const raw = rec?.file ?? rec?.path ?? artifact.file ?? artifact.path;
  if (typeof raw !== "string") return null;
  const filename = raw.split("/").pop() || raw;
  const docKey = DOC_KEY_BY_FILE[filename];
  return docKey ? { filename, docKey } : null;
}