Function buildChannelFileContentParts

packages/bot-teams/src/graph-files.ts:155–199

(
  ref: ChannelMessageRef,
  creds: GraphCredentials,
  config: FileDeliveryConfig = {},
)

 * note explains why (so the caller can tell the user to paste the data).
 */
export async function buildChannelFileContentParts(
  ref: ChannelMessageRef,
  creds: GraphCredentials,
  config: FileDeliveryConfig = {},
): Promise<{ parts: AgentContentPart[]; notes: string[] }> {
  const parts: AgentContentPart[] = [];
  const notes: string[] = [];

  let token: string;
  try {
    token = await acquireAppToken(creds);
  } catch (err) {
    notes.push(`couldn't get a Graph token: ${(err as Error).message}`);
    return { parts, notes };
  }

  let refs: GraphFileRef[];
  try {
    refs = await getMessageFileRefs(ref, token);
  } catch (err) {
    notes.push(
      `couldn't read channel-message files via Graph (is ChannelMessage.Read.Group granted?): ${(err as Error).message}`,
    );
    return { parts, notes };
  }

  const maxFiles = config.maxFiles ?? 5;
  for (const f of refs.slice(0, maxFiles)) {
    let bytes: Buffer;
    try {
      bytes = await downloadSharedFile(f.contentUrl, token);
    } catch (err) {
      notes.push(
        `skipped "${f.name}" (is Files.Read.All granted?): ${(err as Error).message}`,
      );
      continue;
    }
    const mime = mimeFromName(f.name) ?? "application/octet-stream";
    const decoded = decodeFileBytes(f.name, mime, bytes, config);
    if ("note" in decoded) notes.push(decoded.note);
    else parts.push(decoded.part);
  }

  return { parts, notes };
}