/**
 * Inbound file transport for Teams. A Teams message can carry uploaded files;
 * this turns them into AG-UI multimodal content the agent's model can read —
 * images and PDFs as their respective binary parts, and text/CSV/JSON as
 * decoded `text` parts. This is what makes the "upload a CSV → get a chart"
 * flow work: the CSV arrives as text the model can parse before it calls a
 * render tool. Mirrors `@copilotkit/channels-slack`'s `buildFileContentParts`.
 *
 * Teams delivers files two ways, and we handle both:
 *   - Channel/chat file uploads arrive as an attachment of contentType
 *     `application/vnd.microsoft.teams.file.download.info`, whose `content`
 *     holds a pre-authenticated `downloadUrl` (no bearer token needed) plus a
 *     `fileType`. We download from `downloadUrl`.
 *   - Inline media (and the M365 Agents Playground) arrives as an attachment
 *     whose `contentType` is the media MIME and `contentUrl` is either a
 *     `data:` URI (decoded in-process) or an https URL (fetched directly).
 *
 * The bridge is transport-only: it delivers the bytes/text to the agent and
 * lets the app decide what to do with them. Anything it can't represent is
 * skipped with a short note so the agent knows a file was dropped and why.
 */
import type { AgentContentPart } from "@copilotkit/channels-ui";
/** The subset of a Teams `Attachment` we read (matches @microsoft/agents-activity). */
export interface TeamsAttachmentRef {
    contentType: string;
    contentUrl?: string;
    /** `file.download.info` attachments carry the real source here. */
    content?: unknown;
    name?: string;
}
/** Tunables for inbound file handling (all optional; sane defaults). */
export interface FileDeliveryConfig {
    /** Skip a single file larger than this many bytes. Default 8 MiB. */
    maxBytesPerFile?: number;
    /** Process at most this many files per message. Default 5. */
    maxFiles?: number;
    /** Truncate decoded text files to this many bytes. Default 200 KiB. */
    maxTextBytes?: number;
}
/** Best-effort MIME from a filename's extension, or undefined if unknown. */
export declare function mimeFromName(name: string | undefined): string | undefined;
/**
 * Turn downloaded bytes into a single AG-UI content part, or a skip `note` when
 * the type is unsupported or the file exceeds the byte cap. Shared by the
 * attachment path (this module) and the Graph channel path (`graph-files.ts`)
 * so both classify and truncate identically.
 */
export declare function decodeFileBytes(label: string, mime: string, bytes: Buffer, config?: FileDeliveryConfig): {
    part: AgentContentPart;
} | {
    note: string;
};
/**
 * Download a message's attachments and turn them into AG-UI content parts.
 * Returns the parts plus human-readable `notes` for anything skipped (appended
 * to the message as a text part by the caller).
 */
export declare function buildFileContentParts(attachments: readonly TeamsAttachmentRef[], config?: FileDeliveryConfig): Promise<{
    parts: AgentContentPart[];
    notes: string[];
}>;
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