[Support] Disable the Creation of Rooms and Spaces While Allowing DMs (One-on-One or Group)

[LayBraid]

📌 Context and Objective
Hello,
We self-host a Synapse server with several pre-configured spaces.

Our objective is to:
✅ Allow DMs (both one-on-one and group).
⛔ Prevent the creation of new public or private rooms.
⛔ Prevent the creation of new spaces.

We mainly want to enforce these restrictions to better manage resources and avoid the uncontrolled proliferation of rooms and spaces on our self-hosted infrastructure.

📌 Current Management
To restrict the creation of rooms and spaces, we are currently using a plugin based on synapse-user-restrictions.
However, this plugin also blocks the ability to send DMs, which is an unwanted behavior.

🔍 Research Conducted
Before asking this question, we explored different possibilities:

• We identified that rooms have a type (room_type), specifically m.space for spaces.
  Reference: Synapse Admin API - Room Details.
• We wonder if this information could be used to differentiate between spaces, rooms, and DMs to allow only DMs.
• We noticed that the distinction between group DMs and standard rooms seems unclear in the permission management system.
  • Is there a reliable way to make this distinction?
  • Could room_type be used?
• We are unsure about the current support for room_type in restriction rules:
  • Is this functionality poorly implemented, deprecated, or simply never considered for this use case?

❓ Questions

• How can we prevent only the creation of rooms and spaces without blocking DMs?
• Is room_type (e.g., "m.space") usable to restrict only the creation of spaces and rooms?

Thank you in advance for your help! 😊