diff --git a/backend/windmill-api/openapi.yaml b/backend/windmill-api/openapi.yaml
index 52128b89f1..70f001d801 100644
--- a/backend/windmill-api/openapi.yaml
+++ b/backend/windmill-api/openapi.yaml
@@ -2789,6 +2789,24 @@ paths:
                 items:
                   type: string
 
+  /w/{workspace}/workspaces/list_datatables:
+    get:
+      summary: list Datatables
+      operationId: listDataTables
+      tags:
+        - workspace
+      parameters:
+        - $ref: "#/components/parameters/WorkspaceId"
+      responses:
+        "200":
+          description: status
+          content:
+            application/json:
+              schema:
+                type: array
+                items:
+                  type: string
+
   /w/{workspace}/workspaces/edit_ducklake_config:
     post:
       summary: edit ducklake settings
diff --git a/backend/windmill-api/src/workspaces.rs b/backend/windmill-api/src/workspaces.rs
index 14d83a132c..4a2107f385 100644
--- a/backend/windmill-api/src/workspaces.rs
+++ b/backend/windmill-api/src/workspaces.rs
@@ -127,6 +127,7 @@ pub fn workspaced_service() -> Router {
         )
         .route("/edit_ducklake_config", post(edit_ducklake_config))
         .route("/list_ducklakes", get(list_ducklakes))
+        .route("/list_datatables", get(list_datatables))
         .route("/edit_datatable_config", post(edit_datatable_config))
         .route("/edit_git_sync_config", post(edit_git_sync_config))
         .route("/edit_git_sync_repository", post(edit_git_sync_repository))
@@ -1165,6 +1166,28 @@ async fn list_ducklakes(
     Ok(Json(ducklakes))
 }
 
+async fn list_datatables(
+    _authed: ApiAuthed,
+    Extension(db): Extension<DB>,
+    Path(w_id): Path<String>,
+) -> JsonResult<Vec<String>> {
+    let datatables = sqlx::query_scalar!(
+        r#"
+            SELECT jsonb_object_keys(ws.datatable->'datatables') AS datatable_name
+            FROM workspace_settings ws
+            WHERE ws.workspace_id = $1
+        "#,
+        &w_id
+    )
+    .fetch_all(&db)
+    .await?
+    .into_iter()
+    .filter_map(|s| s)
+    .collect();
+
+    Ok(Json(datatables))
+}
+
 async fn edit_ducklake_config(
     authed: ApiAuthed,
     Extension(db): Extension<DB>,
diff --git a/frontend/src/lib/components/Editor.svelte b/frontend/src/lib/components/Editor.svelte
index 6ac50f71df..07e8726215 100644
--- a/frontend/src/lib/components/Editor.svelte
+++ b/frontend/src/lib/components/Editor.svelte
@@ -44,8 +44,8 @@
 		type Preview,
 		ResourceService,
 		type ScriptLang,
-		SettingService,
-		UserService
+		UserService,
+		WorkspaceService
 	} from '$lib/gen'
 	import type { Text } from 'yjs'
 	import {
@@ -1464,17 +1464,17 @@
 		ata?.(deps)
 	}
 
-	let customInstanceDbs = resource([], SettingService.listCustomInstanceDbs)
+	let customTsTypesData = resource([], async () => {
+		let datatables = await WorkspaceService.listDataTables({ workspace: $workspaceStore ?? '' })
+		let ducklakes = await WorkspaceService.listDucklakes({ workspace: $workspaceStore ?? '' })
+		return { datatables, ducklakes }
+	})
 	function setTypescriptCustomTypes() {
+		if (!customTsTypesData.current) return
 		if (lang !== 'typescript') return
-		if (!Object.keys(customInstanceDbs.current ?? {}).length) return
 
-		const ducklakeNames = Object.entries(customInstanceDbs.current ?? {})
-			.filter(([_, { tag }]) => tag === 'ducklake')
-			.map(([name, _]) => name)
-		const datatableNames = Object.entries(customInstanceDbs.current ?? {})
-			.filter(([_, { tag }]) => tag === 'datatable')
-			.map(([name, _]) => name)
+		const ducklakeNames = customTsTypesData.current.ducklakes
+		const datatableNames = customTsTypesData.current.datatables
 
 		const ducklakeNameType = ducklakeNames.length
 			? ducklakeNames.map((name) => JSON.stringify(name)).join(' | ')
@@ -1482,19 +1482,20 @@
 		const datatableNameType = datatableNames.length
 			? datatableNames.map((name) => JSON.stringify(name)).join(' | ')
 			: 'string'
+		const isDucklakeOptional = ducklakeNames.includes('main')
+		const isDataTableOptional = datatableNames.includes('main')
 
-		languages.typescript.typescriptDefaults.addExtraLib(
+		let disposeTs = languages.typescript.typescriptDefaults.addExtraLib(
 			`declare module 'windmill-client' {
 				// Completely replace the module's types
-				export function ducklake(name: ${ducklakeNameType}): SqlTemplateFunction;
-				export function datatable(name: ${datatableNameType}): SqlTemplateFunction;
+				export function ducklake(name${isDucklakeOptional ? '?' : ''}: ${ducklakeNameType}): SqlTemplateFunction;
+				export function datatable(name${isDataTableOptional ? '?' : ''}: ${datatableNameType}): SqlTemplateFunction;
 			}`,
 			'ts:custom_wmill_types.d.ts'
 		)
-		console.log('added custom windmill types', {
-			ducklakeNameType,
-			datatableNameType
-		})
+		return () => {
+			disposeTs.dispose()
+		}
 	}
 
 	async function setTypescriptRTNamespace() {
@@ -1805,7 +1806,7 @@
 		})
 	})
 
-	watch([() => lang, () => customInstanceDbs.current], setTypescriptCustomTypes)
+	watch([() => customTsTypesData.current], setTypescriptCustomTypes)
 </script>
 
 <svelte:window onkeydown={onKeyDown} />