Adds the last missing parity piece vs the established channels: group
chats can be made opt-in via a mention wake word, exactly like the
BlueBubbles iMessage channel.
- require_mention + mention_patterns, read from config.extra (config.yaml
via the generic gateway bridge) or PHOTON_REQUIRE_MENTION /
PHOTON_MENTION_PATTERNS env vars. Same shapes BlueBubbles accepts
(list / JSON / comma / newline), same default Hermes wake words.
- _dispatch_inbound drops unmatched group messages and strips the leading
wake word from matched ones; DMs are never gated.
- plugin.yaml + docs document both knobs and the config.yaml form.
- New test_mention_gating.py (8 tests): default-off, group drop/pass,
wake-word strip, DM bypass, custom patterns, env comma-list, invalid
regex skip.
The config.yaml -> extra bridge needed no core change — the generic
shared-key loop in gateway/config.py already iterates plugin platforms
(_shared_loop_targets += plugin_entries()), so require_mention /
mention_patterns flow through automatically.
Note: outbound media is the one capability Photon still can't reach —
Photon exposes no HTTP send-attachment endpoint yet (documented API
limitation), so the sidecar can't send files. Not faked.
Validation: 34/34 photon tests; E2E confirms config.yaml require_mention
+ custom mention_patterns bridge through load_gateway_config into a live
adapter and gate/strip correctly.
