Follow-up fixes for the matrix-nio → mautrix migration:
1. Module-level mautrix.types import now wrapped in try/except with
proper stub classes. Without this, importing gateway.platforms.matrix
crashes the entire gateway when mautrix isn't installed — even for
users who don't use Matrix. The stubs mirror mautrix's real attribute
names so tests that exercise adapter methods (send, reactions, etc.)
work without the real SDK.
2. Removed _ensure_mautrix_mock() from test_matrix_mention.py — it
permanently installed MagicMock modules in sys.modules via setdefault(),
polluting later tests in the suite. No longer needed since the module
imports cleanly without mautrix.
3. Fixed thread persistence tests to use direct class reference in
monkeypatch.setattr() instead of string-based paths, which broke
when the module was reimported by other tests.
4. Moved the module-importability test to a subprocess to prevent it
from polluting sys.modules (reimporting creates a second module object
with different __dict__, breaking patch.object in subsequent tests).
When enabled, @mentioning the bot in a DM creates a thread (default:
false). Supports both env var and YAML config (matrix.dm_mention_threads).
6 new tests, docs updated.
From #6957
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>
