Fixes#4466.
Root cause: two sequential authorization gates both independently rejected
bot messages, making DISCORD_ALLOW_BOTS completely ineffective.
Gate 1 — `discord.py` `on_message`:
_is_allowed_user ran BEFORE the bot filter, so bot senders were dropped
before the DISCORD_ALLOW_BOTS policy was ever evaluated.
Gate 2 — `gateway/run.py` _is_user_authorized:
The gateway-level allowlist check rejected bot IDs with 'Unauthorized
user: <bot_id>' even if they passed Gate 1.
Fix:
gateway/platforms/discord.py — reorder on_message so DISCORD_ALLOW_BOTS
runs BEFORE _is_allowed_user. Bots permitted by the filter skip the
user allowlist; non-bots are still checked.
gateway/session.py — add is_bot: bool = False to SessionSource so the
gateway layer can distinguish bot senders.
gateway/platforms/base.py — expose is_bot parameter in build_source.
gateway/platforms/discord.py _handle_message — set is_bot=True when
building the SessionSource for bot authors.
gateway/run.py _is_user_authorized — when source.is_bot is True AND
DISCORD_ALLOW_BOTS is 'mentions' or 'all', return True early. Platform
filter already validated the message at on_message; don't re-reject.
Behavior matrix:
| Config | Before | After |
| DISCORD_ALLOW_BOTS=none (default) | Blocked | Blocked |
| DISCORD_ALLOW_BOTS=all | Blocked | Allowed |
| DISCORD_ALLOW_BOTS=mentions + @mention | Blocked | Allowed |
| DISCORD_ALLOW_BOTS=mentions, no mention | Blocked | Blocked |
| Human in DISCORD_ALLOWED_USERS | Allowed | Allowed |
| Human NOT in DISCORD_ALLOWED_USERS | Blocked | Blocked |
Co-authored-by: Hermes Maintainer <hermes@nousresearch.com>