diff --git a/plugins/_whatsapp_integration/helpers/attachment_reader.py b/plugins/_whatsapp_integration/helpers/attachment_reader.py
new file mode 100644
index 000000000..ce9b3456a
--- /dev/null
+++ b/plugins/_whatsapp_integration/helpers/attachment_reader.py
@@ -0,0 +1,40 @@
+"""
+Read attachment files from execution runtime.
+
+No agent/tool dependencies.
+"""
+
+import base64
+import os
+from typing import TypedDict
+
+
+# ------------------------------------------------------------------
+# Data models
+# ------------------------------------------------------------------
+
+class AttachmentData(TypedDict):
+    name: str
+    content_b64: str
+    error: str
+
+
+# ------------------------------------------------------------------
+# File reader
+# ------------------------------------------------------------------
+
+def read_attachment(path: str) -> AttachmentData:
+    try:
+        if not os.path.isfile(path):
+            return AttachmentData(
+                name="", content_b64="", error=f"file not found: {path}")
+        name = os.path.basename(path)
+        with open(path, "rb") as f:
+            content = f.read()
+        return AttachmentData(
+            name=name,
+            content_b64=base64.b64encode(content).decode(),
+            error="",
+        )
+    except Exception as e:
+        return AttachmentData(name="", content_b64="", error=str(e))
diff --git a/plugins/_whatsapp_integration/helpers/attachment_writer.py b/plugins/_whatsapp_integration/helpers/attachment_writer.py
new file mode 100644
index 000000000..52d5e8a1a
--- /dev/null
+++ b/plugins/_whatsapp_integration/helpers/attachment_writer.py
@@ -0,0 +1,35 @@
+"""
+Write attachment files into execution runtime.
+
+No agent/tool dependencies.
+"""
+
+import base64
+from typing import TypedDict
+
+
+# ------------------------------------------------------------------
+# Data models
+# ------------------------------------------------------------------
+
+class WriteResult(TypedDict):
+    path: str
+    error: str
+
+
+# ------------------------------------------------------------------
+# File writer
+# ------------------------------------------------------------------
+
+def write_attachment(rel_path: str, content_b64: str) -> WriteResult:
+    try:
+        from helpers import files
+        abs_path = files.get_abs_path(rel_path)
+        files.make_dirs(abs_path)
+
+        content = base64.b64decode(content_b64)
+        files.write_file_bin(abs_path, content)
+
+        return WriteResult(path=abs_path, error="")
+    except Exception as e:
+        return WriteResult(path="", error=str(e))
diff --git a/plugins/_whatsapp_integration/helpers/handler.py b/plugins/_whatsapp_integration/helpers/handler.py
index 92d56dbc4..ce45508eb 100644
--- a/plugins/_whatsapp_integration/helpers/handler.py
+++ b/plugins/_whatsapp_integration/helpers/handler.py
@@ -5,10 +5,12 @@ Requires agent context.
 """
 
 import asyncio
+import base64
+import os
 import uuid
 
 from agent import Agent, AgentContext, UserMessage
-from helpers import plugins
+from helpers import plugins, files, runtime
 from helpers import message_queue as mq
 from helpers.persist_chat import save_tmp_chat
 from helpers.print_style import PrintStyle
@@ -126,7 +128,8 @@ async def _start_new_chat(config: dict, msg: dict) -> None:
     system_ctx = context.agent0.read_prompt("fw.wa.system_context.md")
 
     msg_id = str(uuid.uuid4())
-    attachments = msg.get("mediaUrls", [])
+    media_urls = msg.get("mediaUrls", [])
+    attachments = await _save_incoming_media(media_urls) if media_urls else []
     mq.log_user_message(
         context, user_msg, attachments, message_id=msg_id, source=" (whatsapp)",
     )
@@ -154,7 +157,8 @@ async def _route_to_chat(
 
     user_msg = _build_user_message(context.agent0, msg, config)
     msg_id = str(uuid.uuid4())
-    attachments = msg.get("mediaUrls", [])
+    media_urls = msg.get("mediaUrls", [])
+    attachments = await _save_incoming_media(media_urls) if media_urls else []
     mq.log_user_message(
         context, user_msg, attachments, message_id=msg_id, source=" (whatsapp)",
     )
@@ -244,12 +248,13 @@ async def send_wa_reply(
     except Exception as e:
         return str(e)
 
-    # Send attachments
+    # Send attachments via RFC (files may live in execution runtime)
     if attachments:
-        for file_path in attachments:
+        host_paths = await _read_attachments_to_host(attachments)
+        for host_path in host_paths:
             try:
                 result = await wa_client.send_media(
-                    base_url, chat_id, file_path,
+                    base_url, chat_id, host_path,
                 )
                 if result.get("error"):
                     PrintStyle.warning(f"WhatsApp: attachment error: {result['error']}")
@@ -257,3 +262,55 @@ async def send_wa_reply(
                 PrintStyle.warning(f"WhatsApp: attachment error: {e}")
 
     return None
+
+
+# ------------------------------------------------------------------
+# Attachment reading (via RFC into execution runtime)
+# ------------------------------------------------------------------
+
+async def _read_attachments_to_host(
+    paths: list[str],
+) -> list[str]:
+    """Read files from execution runtime and write to host media cache."""
+    from plugins._whatsapp_integration.helpers.attachment_reader import read_attachment
+
+    host_paths: list[str] = []
+    for path in paths:
+        data = await runtime.call_development_function(read_attachment, path)
+        if data["error"]:
+            PrintStyle.warning(f"WhatsApp attachment: {data['error']}")
+            continue
+        # Write decoded bytes to host-side media cache
+        host_path = os.path.join(
+            files.get_abs_path(MEDIA_FOLDER), data["name"],
+        )
+        os.makedirs(os.path.dirname(host_path), exist_ok=True)
+        with open(host_path, "wb") as f:
+            f.write(base64.b64decode(data["content_b64"]))
+        host_paths.append(host_path)
+    return host_paths
+
+
+async def _save_incoming_media(
+    media_urls: list[str],
+) -> list[str]:
+    """Save incoming media files into execution runtime via RFC."""
+    from plugins._whatsapp_integration.helpers.attachment_writer import write_attachment
+
+    runtime_paths: list[str] = []
+    for host_path in media_urls:
+        if not os.path.isfile(host_path):
+            continue
+        name = os.path.basename(host_path)
+        with open(host_path, "rb") as f:
+            content_b64 = base64.b64encode(f.read()).decode()
+        rel_path = os.path.join(MEDIA_FOLDER, name)
+        result = await runtime.call_development_function(
+            write_attachment, rel_path, content_b64,
+        )
+        if result.get("error"):
+            PrintStyle.warning(f"WhatsApp media save: {result['error']}")
+            runtime_paths.append(host_path)  # fallback to host path
+        else:
+            runtime_paths.append(result["path"])
+    return runtime_paths
diff --git a/plugins/_whatsapp_integration/whatsapp-bridge/bridge.js b/plugins/_whatsapp_integration/whatsapp-bridge/bridge.js
index 4f9a72176..d98bd0968 100644
--- a/plugins/_whatsapp_integration/whatsapp-bridge/bridge.js
+++ b/plugins/_whatsapp_integration/whatsapp-bridge/bridge.js
@@ -217,17 +217,6 @@ async function startSocket() {
         body = msg.message.imageMessage.caption || '';
         hasMedia = true;
         mediaType = 'image';
-        try {
-          const buf = await downloadMediaMessage(msg, 'buffer', {}, { logger, reuploadRequest: sock.updateMediaMessage });
-          const mime = msg.message.imageMessage.mimetype || 'image/jpeg';
-          const extMap = { 'image/jpeg': '.jpg', 'image/png': '.png', 'image/webp': '.webp', 'image/gif': '.gif' };
-          const ext = extMap[mime] || '.jpg';
-          const filePath = path.join(CACHE_DIR, `img_${randomBytes(6).toString('hex')}${ext}`);
-          writeFileSync(filePath, buf);
-          mediaUrls.push(filePath);
-        } catch (err) {
-          console.error('[bridge] Failed to download image:', err.message);
-        }
       } else if (msg.message.videoMessage) {
         body = msg.message.videoMessage.caption || '';
         hasMedia = true;
@@ -236,11 +225,53 @@ async function startSocket() {
         hasMedia = true;
         mediaType = msg.message.pttMessage ? 'ptt' : 'audio';
       } else if (msg.message.documentMessage) {
-        body = msg.message.documentMessage.caption || msg.message.documentMessage.fileName || '';
+        body = msg.message.documentMessage.caption || '';
         hasMedia = true;
         mediaType = 'document';
       }
 
+      // Download media to disk
+      if (hasMedia) {
+        try {
+          const buf = await downloadMediaMessage(msg, 'buffer', {}, { logger, reuploadRequest: sock.updateMediaMessage });
+          let ext = '.bin';
+          let prefix = mediaType;
+          if (mediaType === 'image') {
+            const mime = msg.message.imageMessage?.mimetype || 'image/jpeg';
+            const extMap = { 'image/jpeg': '.jpg', 'image/png': '.png', 'image/webp': '.webp', 'image/gif': '.gif' };
+            ext = extMap[mime] || '.jpg';
+          } else if (mediaType === 'video') {
+            const mime = msg.message.videoMessage?.mimetype || 'video/mp4';
+            ext = mime.includes('mp4') ? '.mp4' : '.mkv';
+          } else if (mediaType === 'audio' || mediaType === 'ptt') {
+            const mime = msg.message.audioMessage?.mimetype || msg.message.pttMessage?.mimetype || 'audio/ogg';
+            ext = mime.includes('opus') || mime.includes('ogg') ? '.ogg' : '.mp3';
+          } else if (mediaType === 'document') {
+            const docMsg = msg.message.documentMessage;
+            const fileName = docMsg?.fileName || '';
+            if (fileName) {
+              // Use original filename for documents
+              const filePath = path.join(CACHE_DIR, `${randomBytes(4).toString('hex')}_${fileName}`);
+              writeFileSync(filePath, buf);
+              mediaUrls.push(filePath);
+              if (!body) body = fileName;
+            } else {
+              const mime = docMsg?.mimetype || 'application/octet-stream';
+              const docExtMap = { 'application/pdf': '.pdf', 'application/msword': '.doc' };
+              ext = docExtMap[mime] || '.bin';
+            }
+          }
+          // Write file if not already handled (document with fileName)
+          if (mediaUrls.length === 0) {
+            const filePath = path.join(CACHE_DIR, `${prefix}_${randomBytes(6).toString('hex')}${ext}`);
+            writeFileSync(filePath, buf);
+            mediaUrls.push(filePath);
+          }
+        } catch (err) {
+          console.error(`[bridge] Failed to download ${mediaType}:`, err.message);
+        }
+      }
+
       // For media without caption, use a placeholder
       if (hasMedia && !body) {
         body = `[${mediaType} received]`;