Follow-ups on the salvaged #20096 profile-routing feature:
- _profile_name_for_source now returns None unless gateway.multiplex_profiles
is on. Routing stamps source.profile, which namespaces session/batch keys,
but the profile-scoped agent run only activates under multiplexing — without
the gate, configured routes with multiplexing off split batch/session keys
into agent:<profile> while the agent still ran from agent:main.
- Widen the profile-aware _text_batch_key fix from Discord to every adapter
that builds batch keys via build_session_key (telegram, whatsapp, matrix,
feishu, wecom, weixin) — routing is platform-generic, so the batch-key
namespace fix must be too.
- Downgrade the no-route-matched log from INFO to DEBUG (fired on every
unrouted inbound message).
- GatewayConfig.to_dict(): serialize profile_routes as plain dicts
(ProfileRoute dataclasses are not JSON-safe).
- Docs: correct the 'independent of multiplexing' claim in
docs/profile-routing.md (routing requires multiplexing), fix the
platform-only specificity row (0, not 1), and document profile_routes in
website/docs/user-guide/multi-profile-gateways.md.
- Tests: pin the multiplex gate (routes ignored when off, active when on,
build_source end-to-end stays in agent:main when off).