feat: prompt AI to use ReadMediaFile for video attachments instead of Python frame extraction

packages/agent-core/src/profile/default/system.md

@@ -62,6 +62,7 @@ The user may ask you to research on certain topics, process or generate certain
 - Make plans before doing deep or wide research, to ensure you are always on track.
 - Search on the Internet if possible, with carefully-designed search queries to improve efficiency and accuracy.
 - Use proper tools or shell commands or Python packages to process or generate images, videos, PDFs, docs, spreadsheets, presentations, or other multimedia files. Detect if there are already such tools in the environment. If you have to install third-party tools/packages, you MUST ensure that they are installed in a virtual/isolated environment.
+- When the user uploads a video as an attachment (represented as `<video path="...">` in the message), you should use the `ReadMediaFile` tool to read the video content directly instead of writing Python scripts to extract frames or process it manually.
 - Once you generate or edit any images, videos or other media files, try to read it again before proceed, to ensure that the content is as expected.
 - Avoid installing or deleting anything to/from outside of the current working directory. If you have to do so, ask the user for confirmation.