Set _text_batch_delay_seconds = 0 on test adapter fixtures so messages
dispatch immediately (bypassing async batching). This preserves the
existing synchronous assertion patterns while the batching logic is
tested separately in test_text_batching.py.
Move mention stripping outside the `if not is_dm` guard so mentions
are stripped in DMs too. Remove the bare-mention early return so a
message containing only a mention passes through as empty string,
matching Discord's behavior.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Bring Matrix feature parity with Discord by adding mention gating and
auto-threading. Both default to true, matching Discord behavior.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
