Image & Media Support — 2025-12-05

The WhatsApp channel runs via Baileys Web. This document captures the current media handling rules for send, gateway, and agent replies.

Goals

• Send media with optional captions via bot message send --media.
• Allow auto-replies from the web inbox to include media alongside text.
• Keep per-type limits sane and predictable.

CLI Surface

• bot message send --media <path-or-url> [--message <caption>]
  • --media optional; caption can be empty for media-only sends.
  • --dry-run prints the resolved payload; --json emits { channel, to, messageId, mediaUrl, caption }.

WhatsApp Web channel behavior

• Input: local file path or HTTP(S) URL.
• Flow: load into a Buffer, detect media kind, and build the correct payload:
  • Images: resize & recompress to JPEG (max side 2048px) targeting agents.defaults.mediaMaxMb (default 5 MB), capped at 6 MB.
  • Audio/Voice/Video: pass-through up to 16 MB; audio is sent as a voice note (ptt: true).
  • Documents: anything else, up to 100 MB, with filename preserved when available.
• WhatsApp GIF-style playback: send an MP4 with gifPlayback: true (CLI: --gif-playback) so mobile clients loop inline.
• MIME detection prefers magic bytes, then headers, then file extension.
• Caption comes from --message or reply.text; empty caption is allowed.
• Logging: non-verbose shows ↩️/✅; verbose includes size and source path/URL.

Auto-Reply Pipeline

• getReplyFromConfig returns { text?, mediaUrl?, mediaUrls? }.
• When media is present, the web sender resolves local paths or URLs using the same pipeline as bot message send.
• Multiple media entries are sent sequentially if provided.

Inbound Media to Commands (Pi)

• When inbound web messages include media, Bot downloads to a temp file and exposes templating variables:
  • {{MediaUrl}} pseudo-URL for the inbound media.
  • {{MediaPath}} local temp path written before running the command.
• When a per-session Docker sandbox is enabled, inbound media is copied into the sandbox workspace and MediaPath/MediaUrl are rewritten to a relative path like media/inbound/<filename>.
• Media understanding (if configured via tools.media.* or shared tools.media.models) runs before templating and can insert [Image], [Audio], and [Video] blocks into Body.
  • Audio sets {{Transcript}} and uses the transcript for command parsing so slash commands still work.
  • Video and image descriptions preserve any caption text for command parsing.
• By default only the first matching image/audio/video attachment is processed; set tools.media.<cap>.attachments to process multiple attachments.

Limits & Errors

Outbound send caps (WhatsApp web send)

• Images: ~6 MB cap after recompression.
• Audio/voice/video: 16 MB cap; documents: 100 MB cap.
• Oversize or unreadable media → clear error in logs and the reply is skipped.

Media understanding caps (transcription/description)

• Image default: 10 MB (tools.media.image.maxBytes).
• Audio default: 20 MB (tools.media.audio.maxBytes).
• Video default: 50 MB (tools.media.video.maxBytes).
• Oversize media skips understanding, but replies still go through with the original body.

Notes for Tests

• Cover send + reply flows for image/audio/document cases.
• Validate recompression for images (size bound) and voice-note flag for audio.
• Ensure multi-media replies fan out as sequential sends.