Authorization to message the agent is the gate, not the file extension.
Previously the inbound-attachment allowlist (SUPPORTED_DOCUMENT_TYPES) was
opt-OUT on Discord (allow_any_attachment defaulted false) and had no bypass
at all on Telegram/Slack — so an .html (or any non-allowlisted type) was
dropped or hard-rejected before the agent saw it.
Now every authorized upload is cached and surfaced to the agent regardless
of type:
- base.cache_media_bytes(): unknown types cache as octet-stream (or the
caller-supplied MIME) instead of returning None — fixes the chokepoint
that Teams/Telegram-media route through.
- discord/telegram/slack adapters: removed the allowlist reject/skip; any
non-media attachment is typed DOCUMENT and cached. Known types keep their
precise MIME.
- Text inlining now gates on a shared _TEXT_INJECT_EXTENSIONS set (text +
code + config + markup) instead of a blind UTF-8 decode, so binary formats
(PDF/zip/docx) with ASCII headers are never inlined.
- gateway/run.py emits the path-pointing context note for every DOCUMENT,
including non text/application MIME types.
- discord.allow_any_attachment is now a documented no-op kept for config
back-compat.
Validation: 357 gateway tests pass; E2E confirms .html/.bin/custom types
cache, known types stay precise, PDFs are not inlined.
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