feat(spaces): add custom state event types for space roles

Define serde content types for m.space.roles, m.space.role.member,
and m.space.role.room custom state events used by space permission
cascading.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/core/matrix/mod.rs

@@ -2,6 +2,7 @@
 
 pub mod event;
 pub mod pdu;
+pub mod space_roles;
 pub mod state_key;
 pub mod state_res;
 

src/core/matrix/space_roles.rs

@@ -0,0 +1,100 @@
+//! Custom state event content types for space permission cascading.
+//!
+//! These events live in Space rooms and define roles, user-role assignments,
+//! and room-role requirements.
+
+use std::collections::BTreeMap;
+
+use serde::{Deserialize, Serialize};
+
+/// Content for `m.space.roles` (state key: "")
+///
+/// Defines available roles for a Space.
+#[derive(Clone, Debug, Default, Deserialize, Serialize)]
+pub struct SpaceRolesEventContent {
+	pub roles: BTreeMap<String, RoleDefinition>,
+}
+
+/// A single role definition within a Space.
+#[derive(Clone, Debug, Deserialize, Serialize)]
+pub struct RoleDefinition {
+	pub description: String,
+
+	/// If present, users with this role receive this power level in child
+	/// rooms.
+	#[serde(skip_serializing_if = "Option::is_none")]
+	pub power_level: Option<i64>,
+}
+
+/// Content for `m.space.role.member` (state key: user ID)
+///
+/// Assigns roles to a user within a Space.
+#[derive(Clone, Debug, Default, Deserialize, Serialize)]
+pub struct SpaceRoleMemberEventContent {
+	pub roles: Vec<String>,
+}
+
+/// Content for `m.space.role.room` (state key: room ID)
+///
+/// Declares which roles a child room requires for access.
+#[derive(Clone, Debug, Default, Deserialize, Serialize)]
+pub struct SpaceRoleRoomEventContent {
+	pub required_roles: Vec<String>,
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+
+	#[test]
+	fn serialize_space_roles() {
+		let mut roles = BTreeMap::new();
+		roles.insert(
+			"admin".to_owned(),
+			RoleDefinition {
+				description: "Space administrator".to_owned(),
+				power_level: Some(100),
+			},
+		);
+		roles.insert(
+			"nsfw".to_owned(),
+			RoleDefinition {
+				description: "NSFW access".to_owned(),
+				power_level: None,
+			},
+		);
+		let content = SpaceRolesEventContent { roles };
+		let json = serde_json::to_string(&content).unwrap();
+		let deserialized: SpaceRolesEventContent = serde_json::from_str(&json).unwrap();
+		assert_eq!(deserialized.roles.len(), 2);
+		assert_eq!(deserialized.roles["admin"].power_level, Some(100));
+		assert!(deserialized.roles["nsfw"].power_level.is_none());
+	}
+
+	#[test]
+	fn serialize_role_member() {
+		let content = SpaceRoleMemberEventContent {
+			roles: vec!["nsfw".to_owned(), "vip".to_owned()],
+		};
+		let json = serde_json::to_string(&content).unwrap();
+		let deserialized: SpaceRoleMemberEventContent = serde_json::from_str(&json).unwrap();
+		assert_eq!(deserialized.roles, vec!["nsfw", "vip"]);
+	}
+
+	#[test]
+	fn serialize_role_room() {
+		let content = SpaceRoleRoomEventContent {
+			required_roles: vec!["nsfw".to_owned()],
+		};
+		let json = serde_json::to_string(&content).unwrap();
+		let deserialized: SpaceRoleRoomEventContent = serde_json::from_str(&json).unwrap();
+		assert_eq!(deserialized.required_roles, vec!["nsfw"]);
+	}
+
+	#[test]
+	fn empty_roles_deserialize() {
+		let json = r#"{"roles":{}}"#;
+		let content: SpaceRolesEventContent = serde_json::from_str(json).unwrap();
+		assert!(content.roles.is_empty());
+	}
+}