feat: receive media messages (image, video, voice, file)

[jinjiel1994]

Summary

• Download and decrypt media (image/video/voice/file) from WeChat CDN using AES-128-ECB
• Save decrypted media to ~/.claude/channels/wechat/media/ with timestamped filenames
• Forward file paths + metadata to Claude Code via MCP channel notifications
• Claude can then use the Read tool to view images or process media files

Supported message types

Type	Const	Handling
2	MSG_ITEM_IMAGE	Download + decrypt → .jpg
3	MSG_ITEM_VOICE	Download audio + keep existing text transcription
4	MSG_ITEM_FILE	Download + preserve original extension
5	MSG_ITEM_VIDEO	Download + decrypt → .mp4, includes duration/size metadata

Notification format

Media info is appended to the text content as inline annotations:

[image: /path/to/file.jpg]
[video: /path/to/file.mp4 (duration=9, size=2367862)]
[voice: /path/to/file.silk (transcription=你好)]
[file: /path/to/file.pdf (fileName=document.pdf)]

No new dependencies

Uses only node:crypto, node:fs, and native fetch — all already available in the project.

Test plan

• Verified image receive: sent image via WeChat → downloaded, decrypted, Claude read the JPEG successfully
• Verified video receive: sent video via WeChat → downloaded, decrypted to valid MP4 (HEVC 720x1280, 9s)
• End-to-end test: restarted MCP server with changes, sent image from WeChat phone → Claude saw and described image content

🤖 Generated with Claude Code

[Johnixr]

Thanks for the PR! The media receive/send implementation looks good overall. One minor note:

Hardcoded thumbnail dimensions: In generateVideoThumbnail, the ffmpeg scale filter uses scale=224:-1 which preserves aspect ratio, but thumb_height is hardcoded to 398. The actual thumbnail height will vary depending on the video's aspect ratio, so this metadata may not match the real dimensions. Consider reading the actual thumbnail dimensions after generation, or just noting it as a known limitation.

Everything else looks solid — the download/decrypt flow, dual AES key format handling, and error handling are well done.