Inherit cell type when creating new cells with Shift+Enter

frontend/src/core/cells/__tests__/cells.test.ts

@@ -2288,6 +2288,63 @@ describe("cell reducer", () => {
       expect(focusSpy).not.toHaveBeenCalled();
       expect(state.cellIds.inOrderIds).toEqual(initialState.cellIds.inOrderIds);
     });
+
+    it("creates a new SQL cell when moving after a SQL cell", () => {
+      // Create a SQL cell
+      actions.createNewCell({
+        cellId: "__end__",
+        before: false,
+        code: `_df = mo.sql(f"""SELECT * FROM table""")`,
+      });
+
+      const sqlCellId =
+        state.cellIds.inOrderIds[state.cellIds.inOrderIds.length - 1];
+      const initialCellCount = state.cellIds.inOrderIds.length;
+
+      // Move to next cell (should create a new SQL cell)
+      actions.moveToNextCell({
+        cellId: sqlCellId,
+        before: false,
+        noCreate: false,
+      });
+
+      expect(state.cellIds.inOrderIds.length).toBe(initialCellCount + 1);
+      const newCellId =
+        state.cellIds.inOrderIds[state.cellIds.inOrderIds.length - 1];
+      const newCell = state.cellData[newCellId];
+
+      // The new cell should have SQL code (mo.sql)
+      expect(newCell.code).toContain("mo.sql");
+      expect(newCell.code).toContain("_df");
+    });
+
+    it("creates a new Python cell when moving after a Python cell", () => {
+      // Create a Python cell
+      actions.createNewCell({
+        cellId: "__end__",
+        before: false,
+        code: "x = 1",
+      });
+
+      const pythonCellId =
+        state.cellIds.inOrderIds[state.cellIds.inOrderIds.length - 1];
+      const initialCellCount = state.cellIds.inOrderIds.length;
+
+      // Move to next cell (should create a new Python cell)
+      actions.moveToNextCell({
+        cellId: pythonCellId,
+        before: false,
+        noCreate: false,
+      });
+
+      expect(state.cellIds.inOrderIds.length).toBe(initialCellCount + 1);
+      const newCellId =
+        state.cellIds.inOrderIds[state.cellIds.inOrderIds.length - 1];
+      const newCell = state.cellData[newCellId];
+
+      // The new cell should be empty (default Python cell)
+      expect(newCell.code).toBe("");
+    });
   });
 
   describe("untouched cells functionality", () => {

frontend/src/core/cells/cells.ts

@@ -18,6 +18,7 @@ import { Objects } from "@/utils/objects";
 import { extractAllTracebackInfo, type TracebackInfo } from "@/utils/traceback";
 import { createReducerAndAtoms } from "../../utils/createReducer";
 import { foldAllBulk, unfoldAllBulk } from "../codemirror/editing/commands";
+import { LanguageAdapters } from "../codemirror/language/LanguageAdapters";
 import {
   splitEditor,
   updateEditorCodeFromPython,
@@ -955,15 +956,29 @@ const {
     const isPastLastCell = nextCellIndex === column.length;
     const isBeforeFirstCell = nextCellIndex === -1;
 
+    const getNewCellCode = (): string => {
+      const currentCell = state.cellData[cellId];
+      if (!currentCell) {
+        return "";
+      }
+
+      const isSqlCell = LanguageAdapters.sql.isSupported(currentCell.code);
+      if (isSqlCell) {
+        return LanguageAdapters.sql.defaultCode;
+      }
+
+      return "";
+    };
     // Create a new cell at the end and set scrollKey to focus it
     if (isPastLastCell && !noCreate) {
       const newCellId = CellId.create();
+      const newCellCode = getNewCellCode();
       return {
         ...state,
         cellIds: state.cellIds.insertId(newCellId, column.id, nextCellIndex),
         cellData: {
           ...state.cellData,
-          [newCellId]: createCell({ id: newCellId }),
+          [newCellId]: createCell({ id: newCellId, code: newCellCode }),
         },
         cellRuntime: {
           ...state.cellRuntime,
@@ -979,12 +994,13 @@ const {
 
     if (isBeforeFirstCell && !noCreate) {
       const newCellId = CellId.create();
+      const newCellCode = getNewCellCode();
       return {
         ...state,
         cellIds: state.cellIds.insertId(newCellId, column.id, 0),
         cellData: {
           ...state.cellData,
-          [newCellId]: createCell({ id: newCellId }),
+          [newCellId]: createCell({ id: newCellId, code: newCellCode }),
         },
         cellRuntime: {
           ...state.cellRuntime,