fix: msteams attachments + plugin prompt hints

Co-authored-by: Christof <10854026+Evizero@users.noreply.github.com>

extensions/msteams/src/file-consent.ts

@@ -0,0 +1,122 @@
+/**
+ * FileConsentCard utilities for MS Teams large file uploads (>4MB) in personal chats.
+ *
+ * Teams requires user consent before the bot can upload large files. This module provides
+ * utilities for:
+ * - Building FileConsentCard attachments (to request upload permission)
+ * - Building FileInfoCard attachments (to confirm upload completion)
+ * - Parsing fileConsent/invoke activities
+ */
+
+export interface FileConsentCardParams {
+  filename: string;
+  description?: string;
+  sizeInBytes: number;
+  /** Custom context data to include in the card (passed back in the invoke) */
+  context?: Record<string, unknown>;
+}
+
+export interface FileInfoCardParams {
+  filename: string;
+  contentUrl: string;
+  uniqueId: string;
+  fileType: string;
+}
+
+/**
+ * Build a FileConsentCard attachment for requesting upload permission.
+ * Use this for files >= 4MB in personal (1:1) chats.
+ */
+export function buildFileConsentCard(params: FileConsentCardParams) {
+  return {
+    contentType: "application/vnd.microsoft.teams.card.file.consent",
+    name: params.filename,
+    content: {
+      description: params.description ?? `File: ${params.filename}`,
+      sizeInBytes: params.sizeInBytes,
+      acceptContext: { filename: params.filename, ...params.context },
+      declineContext: { filename: params.filename, ...params.context },
+    },
+  };
+}
+
+/**
+ * Build a FileInfoCard attachment for confirming upload completion.
+ * Send this after successfully uploading the file to the consent URL.
+ */
+export function buildFileInfoCard(params: FileInfoCardParams) {
+  return {
+    contentType: "application/vnd.microsoft.teams.card.file.info",
+    contentUrl: params.contentUrl,
+    name: params.filename,
+    content: {
+      uniqueId: params.uniqueId,
+      fileType: params.fileType,
+    },
+  };
+}
+
+export interface FileConsentUploadInfo {
+  name: string;
+  uploadUrl: string;
+  contentUrl: string;
+  uniqueId: string;
+  fileType: string;
+}
+
+export interface FileConsentResponse {
+  action: "accept" | "decline";
+  uploadInfo?: FileConsentUploadInfo;
+  context?: Record<string, unknown>;
+}
+
+/**
+ * Parse a fileConsent/invoke activity.
+ * Returns null if the activity is not a file consent invoke.
+ */
+export function parseFileConsentInvoke(activity: {
+  name?: string;
+  value?: unknown;
+}): FileConsentResponse | null {
+  if (activity.name !== "fileConsent/invoke") return null;
+
+  const value = activity.value as {
+    type?: string;
+    action?: string;
+    uploadInfo?: FileConsentUploadInfo;
+    context?: Record<string, unknown>;
+  };
+
+  if (value?.type !== "fileUpload") return null;
+
+  return {
+    action: value.action === "accept" ? "accept" : "decline",
+    uploadInfo: value.uploadInfo,
+    context: value.context,
+  };
+}
+
+/**
+ * Upload a file to the consent URL provided by Teams.
+ * The URL is provided in the fileConsent/invoke response after user accepts.
+ */
+export async function uploadToConsentUrl(params: {
+  url: string;
+  buffer: Buffer;
+  contentType?: string;
+  fetchFn?: typeof fetch;
+}): Promise<void> {
+  const fetchFn = params.fetchFn ?? fetch;
+  const res = await fetchFn(params.url, {
+    method: "PUT",
+    headers: {
+      "Content-Type": params.contentType ?? "application/octet-stream",
+      "Content-Range": `bytes 0-${params.buffer.length - 1}/${params.buffer.length}`,
+    },
+    body: new Uint8Array(params.buffer),
+  });
+
+  if (!res.ok) {
+    throw new Error(`File upload to consent URL failed: ${res.status} ${res.statusText}`);
+  }
+}