Symptom
-------
The upload action rejected anything over 50 MB with a flat
"File too large (>50MB)" — a number that was both too generous for
images (WA caps at 5 MB) and too restrictive for documents (WA
allows 100 MB). And anything over 1 MB was being rejected even
earlier by Next's default Server Action body limit, with a much
less actionable error.
Fix
---
1. New `lib/whatsapp-media.ts` resolves an uploaded file's MIME type
to a WhatsApp delivery kind and validates it against the
per-kind cap that WA actually enforces:
image → 5 MB image/* except sticker-mode
video → 16 MB video/*
audio → 16 MB audio/*
document → 100 MB anything else (PDFs, office docs, …)
Anything not recognised as image/video/audio falls through to
"document", which is also the Baileys sender path the bot uses
to deliver it. So a .zip or .csv ends up correctly classified
AND correctly limited to the document cap.
Error messages now name the kind and show both the actual size
and the cap: "Image too large (5.2 MB > 5.0 MB limit on
WhatsApp)".
2. `next.config.ts` lifts the Server Action body limit from the 1 MB
default to 100 MB, so document uploads actually reach the action
instead of getting bounced at the framework boundary. The WA
per-kind validator inside the action enforces the real limit
from there.
3. The compose-step upload zone hint now reflects the per-kind caps
("Image up to 5 MB · video / audio up to 16 MB · document up to
100 MB") instead of the wrong flat "up to 50 MB" value.
Tests (17 new cases, total 189)
-------------------------------
- classifyMediaKind: image/video/audio prefix routing, fall-through
to document for unknown / empty / octet-stream / text/plain.
- validateForWhatsApp: at-cap, just-under-cap, just-over-cap for
image (5 MB) / video (16 MB) / audio (16 MB) / document (100 MB);
zero-byte rejected; unknown-mime 60 MB upload accepted as document.
- WA_MAX_BYTES sanity: equals the document cap and is >= every other
per-kind limit (so it's safe to use as the framework body cap).
- formatBytes: bytes / KB (no decimals) / MB (one decimal) rendering.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
yiekheng
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