fix: msteams attachments + plugin prompt hints

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

extensions/msteams/src/graph-chat.ts

@@ -0,0 +1,52 @@
+/**
+ * Native Teams file card attachments for Bot Framework.
+ *
+ * The Bot Framework SDK supports `application/vnd.microsoft.teams.card.file.info`
+ * content type which produces native Teams file cards.
+ *
+ * @see https://learn.microsoft.com/en-us/microsoftteams/platform/bots/how-to/bots-filesv4
+ */
+
+import type { DriveItemProperties } from "./graph-upload.js";
+
+/**
+ * Build a native Teams file card attachment for Bot Framework.
+ *
+ * This uses the `application/vnd.microsoft.teams.card.file.info` content type
+ * which is supported by Bot Framework and produces native Teams file cards
+ * (the same display as when a user manually shares a file).
+ *
+ * @param file - DriveItem properties from getDriveItemProperties()
+ * @returns Attachment object for Bot Framework sendActivity()
+ */
+export function buildTeamsFileInfoCard(file: DriveItemProperties): {
+  contentType: string;
+  contentUrl: string;
+  name: string;
+  content: {
+    uniqueId: string;
+    fileType: string;
+  };
+} {
+  // Extract unique ID from eTag (remove quotes, braces, and version suffix)
+  // Example eTag formats: "{GUID},version" or "\"{GUID},version\""
+  const rawETag = file.eTag;
+  const uniqueId = rawETag
+    .replace(/^["']|["']$/g, "") // Remove outer quotes
+    .replace(/[{}]/g, "") // Remove curly braces
+    .split(",")[0] ?? rawETag; // Take the GUID part before comma
+
+  // Extract file extension from filename
+  const lastDot = file.name.lastIndexOf(".");
+  const fileType = lastDot >= 0 ? file.name.slice(lastDot + 1).toLowerCase() : "";
+
+  return {
+    contentType: "application/vnd.microsoft.teams.card.file.info",
+    contentUrl: file.webDavUrl,
+    name: file.name,
+    content: {
+      uniqueId,
+      fileType,
+    },
+  };
+}