diff --git a/packages/channels/base/src/ChannelBase.ts b/packages/channels/base/src/ChannelBase.ts
index db958f52e..e10e805ce 100644
--- a/packages/channels/base/src/ChannelBase.ts
+++ b/packages/channels/base/src/ChannelBase.ts
@@ -238,6 +238,28 @@ export abstract class ChannelBase {
       promptText = `[Replying to: "${envelope.referencedText}"]\n\n${promptText}`;
     }
 
+    // Resolve attachments: extract image for bridge, append file paths to text
+    let imageBase64 = envelope.imageBase64;
+    let imageMimeType = envelope.imageMimeType;
+    if (envelope.attachments?.length) {
+      const filePaths: string[] = [];
+      for (const att of envelope.attachments) {
+        if (att.type === 'image' && att.data && !imageBase64) {
+          imageBase64 = att.data;
+          imageMimeType = att.mimeType;
+        } else if (att.filePath) {
+          const label = att.type === 'file' ? 'file' : att.type;
+          const name = att.fileName ? ` "${att.fileName}"` : '';
+          filePaths.push(
+            `User sent a ${label}${name}. It has been saved to: ${att.filePath}`,
+          );
+        }
+      }
+      if (filePaths.length > 0) {
+        promptText = promptText + '\n\n' + filePaths.join('\n');
+      }
+    }
+
     // Prepend channel instructions on first message of a session
     if (this.config.instructions && !this.instructedSessions.has(sessionId)) {
       promptText = `${this.config.instructions}\n\n${promptText}`;
@@ -269,8 +291,8 @@ export abstract class ChannelBase {
 
       try {
         const response = await this.bridge.prompt(sessionId, promptText, {
-          imageBase64: envelope.imageBase64,
-          imageMimeType: envelope.imageMimeType,
+          imageBase64,
+          imageMimeType,
         });
 
         if (response) {
diff --git a/packages/channels/base/src/index.ts b/packages/channels/base/src/index.ts
index 111ba2d51..532216478 100644
--- a/packages/channels/base/src/index.ts
+++ b/packages/channels/base/src/index.ts
@@ -16,6 +16,7 @@ export { SenderGate } from './SenderGate.js';
 export type { SenderCheckResult } from './SenderGate.js';
 export { SessionRouter } from './SessionRouter.js';
 export type {
+  Attachment,
   BlockStreamingChunkConfig,
   BlockStreamingCoalesceConfig,
   ChannelConfig,
diff --git a/packages/channels/base/src/types.ts b/packages/channels/base/src/types.ts
index d2424e05a..0a1f91636 100644
--- a/packages/channels/base/src/types.ts
+++ b/packages/channels/base/src/types.ts
@@ -45,6 +45,19 @@ export interface ChannelConfig {
   blockStreamingCoalesce?: BlockStreamingCoalesceConfig;
 }
 
+export interface Attachment {
+  /** Content category. */
+  type: 'image' | 'file' | 'audio' | 'video';
+  /** Base64-encoded data (for images or small files). */
+  data?: string;
+  /** Absolute path to a local file (for large files saved to disk). */
+  filePath?: string;
+  /** MIME type (e.g. "image/jpeg", "application/pdf"). */
+  mimeType: string;
+  /** Original file name from the platform. */
+  fileName?: string;
+}
+
 export interface Envelope {
   channelName: string;
   senderId: string;
@@ -63,6 +76,8 @@ export interface Envelope {
   imageBase64?: string;
   /** MIME type for the image (e.g. "image/jpeg", "image/png"). */
   imageMimeType?: string;
+  /** Structured attachments (images, files, audio, video). */
+  attachments?: Attachment[];
 }
 
 export interface SessionTarget {
diff --git a/packages/channels/dingtalk/src/DingtalkAdapter.ts b/packages/channels/dingtalk/src/DingtalkAdapter.ts
index 4aa468c38..45e40c219 100644
--- a/packages/channels/dingtalk/src/DingtalkAdapter.ts
+++ b/packages/channels/dingtalk/src/DingtalkAdapter.ts
@@ -415,10 +415,17 @@ export class DingtalkChannel extends ChannelBase {
     if (!media) return;
 
     if (mediaType === 'image') {
-      envelope.imageBase64 = media.buffer.toString('base64');
-      envelope.imageMimeType = media.mimeType.startsWith('image/')
+      const mimeType = media.mimeType.startsWith('image/')
         ? media.mimeType
         : 'image/jpeg';
+      envelope.attachments = [
+        ...(envelope.attachments || []),
+        {
+          type: 'image',
+          data: media.buffer.toString('base64'),
+          mimeType,
+        },
+      ];
     } else {
       // Save non-image files to temp dir so the agent can read them
       const dir = join(tmpdir(), 'channel-files');
@@ -427,15 +434,24 @@ export class DingtalkChannel extends ChannelBase {
       const filePath = join(dir, safeName);
       writeFileSync(filePath, media.buffer);
 
-      const prefix =
-        envelope.text &&
-        envelope.text !== `(file: ${fileName || 'file'})` &&
-        envelope.text !== '(audio)' &&
-        envelope.text !== '(video)'
-          ? envelope.text + '\n\n'
-          : '';
-      envelope.text =
-        prefix + `User sent a ${mediaType}. It has been saved to: ${filePath}`;
+      // Clean up placeholder text like "(audio)", "(video)", "(file: name)"
+      if (
+        envelope.text === `(file: ${fileName || 'file'})` ||
+        envelope.text === '(audio)' ||
+        envelope.text === '(video)'
+      ) {
+        envelope.text = '';
+      }
+
+      envelope.attachments = [
+        ...(envelope.attachments || []),
+        {
+          type: mediaType,
+          filePath,
+          mimeType: media.mimeType,
+          fileName: safeName,
+        },
+      ];
     }
   }
 
diff --git a/packages/channels/telegram/src/TelegramAdapter.ts b/packages/channels/telegram/src/TelegramAdapter.ts
index 3445f3986..3912455a5 100644
--- a/packages/channels/telegram/src/TelegramAdapter.ts
+++ b/packages/channels/telegram/src/TelegramAdapter.ts
@@ -123,9 +123,15 @@ export class TelegramChannel extends ChannelBase {
         const filePath = join(dir, fileName);
         writeFileSync(filePath, buf);
 
-        envelope.text =
-          (msg.caption ? msg.caption + '\n\n' : '') +
-          `User sent a file. It has been saved to: ${filePath}`;
+        envelope.text = msg.caption || '';
+        envelope.attachments = [
+          {
+            type: 'file',
+            filePath,
+            mimeType: doc.mime_type || 'application/octet-stream',
+            fileName,
+          },
+        ];
       } catch (err) {
         process.stderr.write(
           `[Telegram:${this.name}] Failed to download document: ${err instanceof Error ? err.message : err}\n`,
diff --git a/packages/channels/weixin/src/WeixinAdapter.ts b/packages/channels/weixin/src/WeixinAdapter.ts
index 3944916bc..cad61e64d 100644
--- a/packages/channels/weixin/src/WeixinAdapter.ts
+++ b/packages/channels/weixin/src/WeixinAdapter.ts
@@ -135,7 +135,14 @@ export class WeixinChannel extends ChannelBase {
           if (!existsSync(dir)) mkdirSync(dir, { recursive: true });
           const filePath = join(dir, file.fileName);
           writeFileSync(filePath, fileData);
-          envelope.text = `User sent a file. It has been saved to: ${filePath}`;
+          envelope.attachments = [
+            {
+              type: 'file',
+              filePath,
+              mimeType: 'application/octet-stream',
+              fileName: file.fileName,
+            },
+          ];
         } catch (err) {
           process.stderr.write(
             `[Weixin:${this.name}] Failed to download file: ${err instanceof Error ? err.message : err}\n`,