Extend the 'Running Many Gateways at Once' user-guide page with a
'one gateway for all profiles (multiplexing)' section, kept to a single page:
- How to opt in (gateway.multiplex_profiles on the default profile) and when to
prefer it vs one-process-per-profile.
- Every contract change a user sees when the flag is on:
1. secondary-profile 'gateway start' is a hard error (--force escape hatch),
2. HTTP-inbound reached via /p/<profile>/ prefix; secondary profiles must NOT
enable a port-binding platform (webhook/api_server/msgraph_webhook/feishu/
wecom_callback/bluebubbles/sms) — config error at startup,
3. per-credential platforms still need their own token per profile,
4. session keys namespaced agent:<profile>: (default stays agent:main:),
5. single PID/lock + aggregated hermes status, per-profile runtime_status.json.
- What does NOT change: per-profile .env credential isolation (stricter, incl.
MCP/Kanban subprocess env), Kanban, profile-scoped skills/memory/SOUL, routing.
All inert when the flag is off.
Ben Barclay
2dd285f9b3