The Channels API (PUT /api/messaging/platforms/{id}) accepted and persisted
enabling a port-binding platform on a secondary profile while
gateway.multiplex_profiles is on — a config the gateway only rejects on its
next start, aborting startup with MultiplexConfigError for every multiplexed
profile.
Validate before any .env/config.yaml write and return 409 for the enable
attempt. Disabling and clearing env stay allowed so an already-invalid
profile can be repaired. The port-binding platform set moves to
gateway/config.py (PORT_BINDING_PLATFORM_VALUES) as the single source of
truth shared by gateway startup validation and the dashboard, so the two
policies cannot drift. Platform config mutations now get a names-only audit
log line.
Fixes#62791
PRATHAMESH75
e984a61306