Switch to shared sync for spaces and related entities

- Add apply_shared_change handlers for Space, SpaceGroup, and SpaceItem
to upsert by UUID and delete by UUID

- Update registry to use shared_with_query and call apply_shared_change;
remove deletion hooks

- Enhance SyncMonitorPopover to display a colored state badge in a
header bar

core/src/infra/db/entities/space.rs

@@ -108,4 +108,100 @@ impl Syncable for Model {
 
 		Ok(sync_results)
 	}
+
+	async fn apply_shared_change(
+		entry: crate::infra::sync::SharedChangeEntry,
+		db: &DatabaseConnection,
+	) -> Result<(), sea_orm::DbErr> {
+		use crate::infra::sync::ChangeType;
+		use sea_orm::{ActiveModelTrait, ColumnTrait, EntityTrait, QueryFilter, Set, NotSet};
+
+		match entry.change_type {
+			ChangeType::Insert | ChangeType::Update => {
+				let data = entry.data.as_object().ok_or_else(|| {
+					sea_orm::DbErr::Custom("Space data is not an object".to_string())
+				})?;
+
+				let uuid: Uuid = serde_json::from_value(
+					data.get("uuid")
+						.ok_or_else(|| sea_orm::DbErr::Custom("Missing uuid".to_string()))?
+						.clone(),
+				)
+				.map_err(|e| sea_orm::DbErr::Custom(format!("Invalid uuid: {}", e)))?;
+
+				let active = ActiveModel {
+					id: NotSet,
+					uuid: Set(uuid),
+					name: Set(serde_json::from_value(
+						data.get("name")
+							.ok_or_else(|| sea_orm::DbErr::Custom("Missing name".to_string()))?
+							.clone(),
+					)
+					.map_err(|e| sea_orm::DbErr::Custom(format!("Invalid name: {}", e)))?),
+					icon: Set(serde_json::from_value(
+						data.get("icon")
+							.ok_or_else(|| sea_orm::DbErr::Custom("Missing icon".to_string()))?
+							.clone(),
+					)
+					.map_err(|e| sea_orm::DbErr::Custom(format!("Invalid icon: {}", e)))?),
+					color: Set(serde_json::from_value(
+						data.get("color")
+							.ok_or_else(|| sea_orm::DbErr::Custom("Missing color".to_string()))?
+							.clone(),
+					)
+					.map_err(|e| sea_orm::DbErr::Custom(format!("Invalid color: {}", e)))?),
+					order: Set(serde_json::from_value(
+						data.get("order")
+							.ok_or_else(|| sea_orm::DbErr::Custom("Missing order".to_string()))?
+							.clone(),
+					)
+					.map_err(|e| sea_orm::DbErr::Custom(format!("Invalid order: {}", e)))?),
+					created_at: Set(serde_json::from_value(
+						data.get("created_at")
+							.ok_or_else(|| sea_orm::DbErr::Custom("Missing created_at".to_string()))?
+							.clone(),
+					)
+					.map_err(|e| sea_orm::DbErr::Custom(format!("Invalid created_at: {}", e)))?),
+					updated_at: Set(serde_json::from_value(
+						data.get("updated_at")
+							.ok_or_else(|| sea_orm::DbErr::Custom("Missing updated_at".to_string()))?
+							.clone(),
+					)
+					.map_err(|e| sea_orm::DbErr::Custom(format!("Invalid updated_at: {}", e)))?),
+				};
+
+				// Upsert by UUID
+				let existing = Entity::find().filter(Column::Uuid.eq(uuid)).one(db).await?;
+
+				if let Some(existing_model) = existing {
+					let mut active = active;
+					active.id = Set(existing_model.id);
+					active.update(db).await?;
+				} else {
+					active.insert(db).await?;
+				}
+
+				Ok(())
+			}
+			ChangeType::Delete => {
+				let data = entry.data.as_object().ok_or_else(|| {
+					sea_orm::DbErr::Custom("Space data is not an object".to_string())
+				})?;
+
+				let uuid: Uuid = serde_json::from_value(
+					data.get("uuid")
+						.ok_or_else(|| sea_orm::DbErr::Custom("Missing uuid".to_string()))?
+						.clone(),
+				)
+				.map_err(|e| sea_orm::DbErr::Custom(format!("Invalid uuid: {}", e)))?;
+
+				Entity::delete_many()
+					.filter(Column::Uuid.eq(uuid))
+					.exec(db)
+					.await?;
+
+				Ok(())
+			}
+		}
+	}
 }

core/src/infra/db/entities/space_group.rs

@@ -118,4 +118,108 @@ impl Syncable for Model {
 
 		Ok(sync_results)
 	}
+
+	async fn apply_shared_change(
+		entry: crate::infra::sync::SharedChangeEntry,
+		db: &DatabaseConnection,
+	) -> Result<(), sea_orm::DbErr> {
+		use crate::infra::sync::{ChangeType, fk_mapper};
+		use sea_orm::{ActiveModelTrait, ColumnTrait, EntityTrait, QueryFilter, Set, NotSet};
+
+		match entry.change_type {
+			ChangeType::Insert | ChangeType::Update => {
+				// Map UUIDs to local IDs for FK fields
+				let data =
+					fk_mapper::map_sync_json_to_local(entry.data, Self::foreign_key_mappings(), db)
+						.await
+						.map_err(|e| sea_orm::DbErr::Custom(format!("FK mapping failed: {}", e)))?;
+
+				let data = data.as_object().ok_or_else(|| {
+					sea_orm::DbErr::Custom("SpaceGroup data is not an object".to_string())
+				})?;
+
+				let uuid: Uuid = serde_json::from_value(
+					data.get("uuid")
+						.ok_or_else(|| sea_orm::DbErr::Custom("Missing uuid".to_string()))?
+						.clone(),
+				)
+				.map_err(|e| sea_orm::DbErr::Custom(format!("Invalid uuid: {}", e)))?;
+
+				let space_id: i32 = serde_json::from_value(
+					data.get("space_id")
+						.ok_or_else(|| sea_orm::DbErr::Custom("Missing space_id".to_string()))?
+						.clone(),
+				)
+				.map_err(|e| sea_orm::DbErr::Custom(format!("Invalid space_id: {}", e)))?;
+
+				let active = ActiveModel {
+					id: NotSet,
+					uuid: Set(uuid),
+					space_id: Set(space_id),
+					name: Set(serde_json::from_value(
+						data.get("name")
+							.ok_or_else(|| sea_orm::DbErr::Custom("Missing name".to_string()))?
+							.clone(),
+					)
+					.map_err(|e| sea_orm::DbErr::Custom(format!("Invalid name: {}", e)))?),
+					group_type: Set(serde_json::from_value(
+						data.get("group_type")
+							.ok_or_else(|| sea_orm::DbErr::Custom("Missing group_type".to_string()))?
+							.clone(),
+					)
+					.map_err(|e| sea_orm::DbErr::Custom(format!("Invalid group_type: {}", e)))?),
+					is_collapsed: Set(serde_json::from_value(
+						data.get("is_collapsed")
+							.ok_or_else(|| sea_orm::DbErr::Custom("Missing is_collapsed".to_string()))?
+							.clone(),
+					)
+					.map_err(|e| sea_orm::DbErr::Custom(format!("Invalid is_collapsed: {}", e)))?),
+					order: Set(serde_json::from_value(
+						data.get("order")
+							.ok_or_else(|| sea_orm::DbErr::Custom("Missing order".to_string()))?
+							.clone(),
+					)
+					.map_err(|e| sea_orm::DbErr::Custom(format!("Invalid order: {}", e)))?),
+					created_at: Set(serde_json::from_value(
+						data.get("created_at")
+							.ok_or_else(|| sea_orm::DbErr::Custom("Missing created_at".to_string()))?
+							.clone(),
+					)
+					.map_err(|e| sea_orm::DbErr::Custom(format!("Invalid created_at: {}", e)))?),
+				};
+
+				// Upsert by UUID
+				let existing = Entity::find().filter(Column::Uuid.eq(uuid)).one(db).await?;
+
+				if let Some(existing_model) = existing {
+					let mut active = active;
+					active.id = Set(existing_model.id);
+					active.update(db).await?;
+				} else {
+					active.insert(db).await?;
+				}
+
+				Ok(())
+			}
+			ChangeType::Delete => {
+				let data = entry.data.as_object().ok_or_else(|| {
+					sea_orm::DbErr::Custom("SpaceGroup data is not an object".to_string())
+				})?;
+
+				let uuid: Uuid = serde_json::from_value(
+					data.get("uuid")
+						.ok_or_else(|| sea_orm::DbErr::Custom("Missing uuid".to_string()))?
+						.clone(),
+				)
+				.map_err(|e| sea_orm::DbErr::Custom(format!("Invalid uuid: {}", e)))?;
+
+				Entity::delete_many()
+					.filter(Column::Uuid.eq(uuid))
+					.exec(db)
+					.await?;
+
+				Ok(())
+			}
+		}
+	}
 }

core/src/infra/db/entities/space_item.rs

@@ -124,4 +124,104 @@ impl Syncable for Model {
 
 		Ok(sync_results)
 	}
+
+	async fn apply_shared_change(
+		entry: crate::infra::sync::SharedChangeEntry,
+		db: &DatabaseConnection,
+	) -> Result<(), sea_orm::DbErr> {
+		use crate::infra::sync::{ChangeType, fk_mapper};
+		use sea_orm::{ActiveModelTrait, ColumnTrait, EntityTrait, QueryFilter, Set, NotSet};
+
+		match entry.change_type {
+			ChangeType::Insert | ChangeType::Update => {
+				// Map UUIDs to local IDs for FK fields
+				let data =
+					fk_mapper::map_sync_json_to_local(entry.data, Self::foreign_key_mappings(), db)
+						.await
+						.map_err(|e| sea_orm::DbErr::Custom(format!("FK mapping failed: {}", e)))?;
+
+				let data = data.as_object().ok_or_else(|| {
+					sea_orm::DbErr::Custom("SpaceItem data is not an object".to_string())
+				})?;
+
+				let uuid: Uuid = serde_json::from_value(
+					data.get("uuid")
+						.ok_or_else(|| sea_orm::DbErr::Custom("Missing uuid".to_string()))?
+						.clone(),
+				)
+				.map_err(|e| sea_orm::DbErr::Custom(format!("Invalid uuid: {}", e)))?;
+
+				let space_id: i32 = serde_json::from_value(
+					data.get("space_id")
+						.ok_or_else(|| sea_orm::DbErr::Custom("Missing space_id".to_string()))?
+						.clone(),
+				)
+				.map_err(|e| sea_orm::DbErr::Custom(format!("Invalid space_id: {}", e)))?;
+
+				let group_id: Option<i32> = serde_json::from_value(
+					data.get("group_id")
+						.ok_or_else(|| sea_orm::DbErr::Custom("Missing group_id".to_string()))?
+						.clone(),
+				)
+				.map_err(|e| sea_orm::DbErr::Custom(format!("Invalid group_id: {}", e)))?;
+
+				let active = ActiveModel {
+					id: NotSet,
+					uuid: Set(uuid),
+					space_id: Set(space_id),
+					group_id: Set(group_id),
+					item_type: Set(serde_json::from_value(
+						data.get("item_type")
+							.ok_or_else(|| sea_orm::DbErr::Custom("Missing item_type".to_string()))?
+							.clone(),
+					)
+					.map_err(|e| sea_orm::DbErr::Custom(format!("Invalid item_type: {}", e)))?),
+					order: Set(serde_json::from_value(
+						data.get("order")
+							.ok_or_else(|| sea_orm::DbErr::Custom("Missing order".to_string()))?
+							.clone(),
+					)
+					.map_err(|e| sea_orm::DbErr::Custom(format!("Invalid order: {}", e)))?),
+					created_at: Set(serde_json::from_value(
+						data.get("created_at")
+							.ok_or_else(|| sea_orm::DbErr::Custom("Missing created_at".to_string()))?
+							.clone(),
+					)
+					.map_err(|e| sea_orm::DbErr::Custom(format!("Invalid created_at: {}", e)))?),
+				};
+
+				// Upsert by UUID
+				let existing = Entity::find().filter(Column::Uuid.eq(uuid)).one(db).await?;
+
+				if let Some(existing_model) = existing {
+					let mut active = active;
+					active.id = Set(existing_model.id);
+					active.update(db).await?;
+				} else {
+					active.insert(db).await?;
+				}
+
+				Ok(())
+			}
+			ChangeType::Delete => {
+				let data = entry.data.as_object().ok_or_else(|| {
+					sea_orm::DbErr::Custom("SpaceItem data is not an object".to_string())
+				})?;
+
+				let uuid: Uuid = serde_json::from_value(
+					data.get("uuid")
+						.ok_or_else(|| sea_orm::DbErr::Custom("Missing uuid".to_string()))?
+						.clone(),
+				)
+				.map_err(|e| sea_orm::DbErr::Custom(format!("Invalid uuid: {}", e)))?;
+
+				Entity::delete_many()
+					.filter(Column::Uuid.eq(uuid))
+					.exec(db)
+					.await?;
+
+				Ok(())
+			}
+		}
+	}
 }

core/src/infra/sync/registry.rs

@@ -476,14 +476,14 @@ fn initialize_registry() -> HashMap<String, SyncableModelRegistration> {
 		),
 	);
 
-	// Space models (device-owned)
+	// Space models (shared)
 	registry.insert(
 		"space".to_string(),
-		SyncableModelRegistration::device_owned(
+		SyncableModelRegistration::shared_with_query(
 			"space",
 			"spaces",
-			|data, db| {
-				Box::pin(async move { space::Model::apply_state_change(data, db.as_ref()).await })
+			|entry, db| {
+				Box::pin(async move { space::Model::apply_shared_change(entry, db.as_ref()).await })
 			},
 			|device_id, since, cursor, batch_size, db| {
 				Box::pin(async move {
@@ -491,20 +491,17 @@ fn initialize_registry() -> HashMap<String, SyncableModelRegistration> {
 						.await
 				})
 			},
-			Some(|uuid, db| {
-				Box::pin(async move { space::Model::apply_deletion(uuid, db.as_ref()).await })
-			}),
 		),
 	);
 
 	registry.insert(
 		"space_group".to_string(),
-		SyncableModelRegistration::device_owned(
+		SyncableModelRegistration::shared_with_query(
 			"space_group",
 			"space_groups",
-			|data, db| {
+			|entry, db| {
 				Box::pin(async move {
-					space_group::Model::apply_state_change(data, db.as_ref()).await
+					space_group::Model::apply_shared_change(entry, db.as_ref()).await
 				})
 			},
 			|device_id, since, cursor, batch_size, db| {
@@ -519,20 +516,17 @@ fn initialize_registry() -> HashMap<String, SyncableModelRegistration> {
 					.await
 				})
 			},
-			Some(|uuid, db| {
-				Box::pin(async move { space_group::Model::apply_deletion(uuid, db.as_ref()).await })
-			}),
 		),
 	);
 
 	registry.insert(
 		"space_item".to_string(),
-		SyncableModelRegistration::device_owned(
+		SyncableModelRegistration::shared_with_query(
 			"space_item",
 			"space_items",
-			|data, db| {
+			|entry, db| {
 				Box::pin(async move {
-					space_item::Model::apply_state_change(data, db.as_ref()).await
+					space_item::Model::apply_shared_change(entry, db.as_ref()).await
 				})
 			},
 			|device_id, since, cursor, batch_size, db| {
@@ -547,9 +541,6 @@ fn initialize_registry() -> HashMap<String, SyncableModelRegistration> {
 					.await
 				})
 			},
-			Some(|uuid, db| {
-				Box::pin(async move { space_item::Model::apply_deletion(uuid, db.as_ref()).await })
-			}),
 		),
 	);
 

packages/interface/src/components/SyncMonitor/SyncMonitorPopover.tsx

@@ -93,22 +93,47 @@ export function SyncMonitorPopover({ className }: SyncMonitorPopoverProps) {
 function SyncMonitorContent({ showActivityFeed }: { showActivityFeed: boolean }) {
 	const sync = useSyncMonitor();
 
+	const getStateColor = (state: string) => {
+		switch (state) {
+			case 'Ready':
+				return 'bg-green-500';
+			case 'Backfilling':
+				return 'bg-yellow-500';
+			case 'CatchingUp':
+				return 'bg-blue-500';
+			case 'Uninitialized':
+				return 'bg-ink-faint';
+			case 'Paused':
+				return 'bg-ink-dull';
+			default:
+				return 'bg-ink-faint';
+		}
+	};
+
 	return (
-		<motion.div
-			className="overflow-y-auto no-scrollbar"
-			initial={false}
-			animate={{
-				height: showActivityFeed
-					? Math.min(sync.recentActivity.length * 40 + 16, 400)
-					: Math.min(sync.peers.length * 80 + 16, 400),
-			}}
-			transition={{ duration: 0.2, ease: [0.25, 1, 0.5, 1] }}
-		>
-			{showActivityFeed ? (
-				<ActivityFeed activities={sync.recentActivity} />
-			) : (
-				<PeerList peers={sync.peers} currentState={sync.currentState} />
-			)}
-		</motion.div>
+		<>
+			<div className="px-4 py-2 border-b border-app-line bg-app-box/50">
+				<div className="flex items-center gap-2">
+					<div className={`size-2 rounded-full ${getStateColor(sync.currentState)}`} />
+					<span className="text-xs font-medium text-ink-dull">{sync.currentState}</span>
+				</div>
+			</div>
+			<motion.div
+				className="overflow-y-auto no-scrollbar"
+				initial={false}
+				animate={{
+					height: showActivityFeed
+						? Math.min(sync.recentActivity.length * 40 + 16, 400)
+						: Math.min(sync.peers.length * 80 + 16, 400),
+				}}
+				transition={{ duration: 0.2, ease: [0.25, 1, 0.5, 1] }}
+			>
+				{showActivityFeed ? (
+					<ActivityFeed activities={sync.recentActivity} />
+				) : (
+					<PeerList peers={sync.peers} currentState={sync.currentState} />
+				)}
+			</motion.div>
+		</>
 	);
 }