fix(matrix): scope require_mention/process_notices/session_scope/auto_thread/dm_mention_threads/max_message_length to the active profile under multiplexing

[nftpoetrist]

Problem

plugins/platforms/matrix/adapter.py only got a partial version of the same-day multiplex-scoping treatment applied to Mattermost/DingTalk/IRC/WhatsApp today. Its E2EE crypto-store path and MATRIX_RECOVERY_KEY read were already fixed (#69090), but several other settings were not:

• require_mention, thread_require_mention, max_message_length already checked config.extra first, but fell back to raw os.getenv when extra was absent.
• process_notices, session_scope, auto_thread, dm_mention_threads never consulted config.extra at all — raw os.getenv only.
• allow_room_mentions, dm_auto_thread have no config.yaml path at all (env-only knobs) — raw os.getenv only.
• _apply_yaml_config wrote MATRIX_REQUIRE_MENTION / MATRIX_PROCESS_NOTICES / MATRIX_SESSION_SCOPE / MATRIX_AUTO_THREAD / MATRIX_DM_MENTION_THREADS / MATRIX_MAX_MESSAGE_LENGTH into the process-global os.environ unconditionally (guarded only by not os.getenv(...), first-writer-wins) — the same apply_yaml_config_fn bug class already fixed for Mattermost/DingTalk/WhatsApp in this series.

Under gateway.multiplex_profiles, os.environ holds the default profile's YAML→env bridge output. A secondary profile with its own (or no) Matrix config could silently have its mention-gating, notice-processing, session-scope, auto-threading, and outbound chunk-size decisions driven by the default profile's settings for the adapter's entire runtime lifetime.

Fix

Mirrors the Mattermost/DingTalk apply_yaml_config_fn pattern (see 56d869d):

• Add _profile_scoped_config_load() (same helper/name as Mattermost/DingTalk) — true when running inside a multiplexed secondary profile's scope.
• Rewrite _apply_yaml_config to skip the env-bridge write for require_mention / process_notices / session_scope / auto_thread / dm_mention_threads / max_message_length under a scoped secondary profile, returning those values as a dict merged into that profile's own PlatformConfig.extra instead (the generic apply_yaml_config_fn dispatcher in gateway/config.py already does extra.update(seeded)).
• Give _startup_env_secret() — Matrix's existing scoped-secret helper, previously used only for MATRIX_ACCESS_TOKEN/MATRIX_PASSWORD/MATRIX_HOMESERVER — an optional default parameter so non-credential settings can reuse it too (backward compatible; existing 1-arg call sites unaffected).
• Switch every affected read site to read config.extra first, falling back to _startup_env_secret() instead of raw os.getenv: _parse_require_mention, _parse_thread_require_mention, _resolve_max_message_length, and (newly extra-aware) process_notices, session_scope, auto_thread, dm_mention_threads in __init__.
• MATRIX_ALLOW_ROOM_MENTIONS/MATRIX_DM_AUTO_THREAD have no config.yaml path at all; scope the read itself via _startup_env_secret rather than inventing a new YAML bridge for them.

Explicitly out of scope

allowed_users/allowed_rooms/free_response_rooms/ignore_user_patterns/GATEWAY_ALLOW_ALL_USERS are not touched here. I checked open PRs first:

• fix(gateway): read adapter allowlists through profile secret scope #88559 ("read adapter allowlists through profile secret scope", open) rewrites the same _apply_yaml_config function and independently defines the same-named _profile_scoped_config_load() helper — but exclusively for the allowlist fields above (_resolve_allowlist() in its diff). Its diff to plugins/platforms/matrix/adapter.py never touches require_mention/process_notices/session_scope/auto_thread/dm_mention_threads/max_message_length. Textual proximity (same function), zero semantic overlap with this PR — I verified via gh pr diff 88559.
• fix(matrix): add missing dm_auto_thread config→env bridge #96039 ("add missing dm_auto_thread config→env bridge", open) is a 2-line feature-add to _apply_yaml_config's write side, giving dm_auto_thread a config.yaml path for the first time. It's complementary, not overlapping: this PR only scopes dm_auto_thread's read side (raw os.getenv → _startup_env_secret) and deliberately does not add a YAML bridge for it, to avoid stepping on that PR's feature.

Both will need a routine rebase against this PR's _apply_yaml_config rewrite (same function, no semantic conflict).

Tests

Adds TestMultiplexProfileScope to tests/gateway/test_matrix.py (6 tests), mirroring the fixture/assertion style established in tests/gateway/test_irc_adapter.py's TestMultiplexProfileScope:

• test_secondary_extra_wins_over_default_profile_env
• test_secondary_missing_keys_fail_closed
• test_secondary_own_env_only_scope_wins_over_default_profile_env
• test_apply_yaml_config_scoped_skips_env_write_and_seeds_extra
• test_apply_yaml_config_unscoped_default_profile_still_writes_env (non-differentiating regression guard)

Mutation-verified: reverted the production fix (kept the tests) and confirmed 4 of 5 differentiating tests fail against pre-fix code; the 5th (guarding that the default/unscoped profile keeps writing the env bridge) correctly passes either way. Restored the fix — all tests pass again.

Full results with the fix applied:

• tests/gateway/test_matrix.py — 117 passed
• tests/gateway/test_matrix_crypto_store_per_profile.py, test_matrix_recovery_key_scope.py, test_matrix_plugin_setup.py, test_matrix_mention.py, test_matrix_message_length.py — 28 passed
• tests/gateway/test_matrix_dm_invite_recording.py, test_matrix_approval_reaction_fail_closed.py, test_matrix_exec_approval.py, test_matrix_voice.py, test_matrix_project_context_isolation.py, test_matrix_message_event_metadata.py — 18 passed, 1 skipped (pre-existing, unrelated)
• tests/gateway/test_adapter_startup_secret_scope.py — 75 passed
• tests/gateway/test_config.py — 63 passed
• ruff check on both changed files — clean

[Enough1122]

AI code review — automated review for reference; please use your judgment.

PR #102097 — fix(matrix): scope require_mention/process_notices/session_scope to the active profile

• plugins/platforms/matrix/adapter.py:982-995 — _startup_env_secret(name, default="") gains a default so non-credential settings keep their non-empty defaults through the same scoped read (scoped miss → default, no borrowing process env; only unscoped multiplex-default falls back to os.environ).
• Read sites now check config.extra first with the scoped env as fallback: :572-578 (max_message_length), :1309-1342 (allow_room_mentions/auto_thread/dm_auto_thread/dm_mention_threads/session_scope/process_notices), :1439-1445 and :1460-1466 (require_mention parsers). Mirrors the Mattermost/DingTalk fix for this bug class.
• :5405-5492 — _profile_scoped_config_load() discriminator (multiplex-active + secret scope installed, same as Buzz/Discord/Telegram/WhatsApp/LINE/DingTalk/Mattermost/IRC) plus _apply_yaml_config returning seeded extra instead of writing process-global env under secondary scope (env still wins over YAML single-profile via not os.getenv guards). Allowlist fields intentionally stay on the legacy path, flagged for the follow-up fix.
• Tests tests/gateway/test_matrix.py:3343-3546 pin secondary-extra-wins, missing-keys-fail-closed, own-env-only scope, and scoped-vs-unscoped yaml application.

Non-blocking:

• _reactions_enabled still reads raw os.getenv; presumably covered by the allowlist follow-up, but confirm it's on that list so it isn't orphaned between the two fixes.

Verdict: LGTM.

[teknium1]

Superseded by #108705 (on main as 199c66f). The Matrix reads you listed — require_mention, thread_require_mention, process_notices, session_scope, auto_thread, dm_mention_threads, max_message_length, plus the env-only allow_room_mentions/dm_auto_thread and e2ee_mode — now go through _get_scoped_secret (_env_truthy/_extra_truthy fall back to the scoped reader, not os.getenv), and _apply_yaml_config bridges through yaml_env_setter, which refuses to write under a secondary scope. Your branch had drifted off current main and carried more tests than we keep per fix, so it was re-done in that smaller shape rather than cherry-picked. Thanks, @nftpoetrist.