hermes - 💡(How to fix) Fix Gateway config-bridging skips plugin platforms not in the Platform enum (channel_prompts silently no-op for LINE) [1 pull requests]

Bug

The gateway's per-chat config bridging (gateway/config.py) only runs for platforms in the hard-coded Platform enum. A platform provided by a plugin (e.g. the bundled LINE adapter in plugins/platforms/line/) is silently skipped, so its top-level config block — including channel_prompts and every other bridged key — never reaches the adapter's extra. The platform still connects and serves traffic; it just loses all per-chat config bridging, with no error.

Root cause

The shared-key bridging builds its target list by converting config keys to Platform(...) and dropping anything that isn't an enum member:

try:
    _plat = Platform(_entry.name)
except (ValueError, KeyError):
    continue

Platform enumerates LOCAL/TELEGRAM/DISCORD/WHATSAPP/SLACK/SIGNAL/MATTERMOST/MATRIX/HOMEASSISTANT/EMAIL/SMS/DINGTALK/API_SERVER/WEBHOOK/MSGRAPH_WEBHOOK/FEISHU/WECOM/WECOM_CALLBACK/WEIXIN/BLUEBUBBLES/QQBOT/YUANBAO — no line, and no entry for any other plugin-provided platform. So Platform("line") raises ValueError, the whole line: block is continued past, and gateway/platforms/base.py later reads channel_prompts from a config.extra that was never populated.

Reproduce

1. With the bundled LINE platform plugin, configure a gateway profile with a top-level line: block containing channel_prompts: {"<chat_id>": "..."}.
2. hermes --profile <p> gateway run — LINE connects and the webhook listens.
3. Messages from that chat get the base system prompt only; the per-chat channel_prompt is never applied. (Same for any other key the bridging normally passes through, e.g. webhook_path did not apply either.)

Impact

• channel_prompts (per-chat personas) and all other bridged per-chat/per-group config silently don't work for LINE — and for any future plugin-provided platform not added to the enum. Plugin platforms are second-class vs built-ins, with no signal that config was dropped.
• Directly blocks per-group personas on native LINE (relevant to the active LINE work — many open PRs; tracking #16611).

Suggested fix (approach is maintainers' call)

Either (a) add LINE = "line" (and other plugin platforms) to the Platform enum and wire it into the bridging, or — cleaner long-term — (b) resolve plugin-provided platforms generically (via the plugin registry) in the bridging instead of gating on the core enum, so any registered platform plugin gets per-chat config bridging automatically.

Related: #27548 (plugin-platform discovery key namespacing — same "plugin platforms are second-class" theme, different mechanism); #16611 (LINE adapter tracker).

🤖 Filed with Claude Code after hitting this while wiring per-chat channel_prompts on the LINE adapter.