diff --git a/gui/src/app/Project/ProjectReducer.ts b/gui/src/app/Project/ProjectReducer.ts
index 032d8cd..e791c27 100644
--- a/gui/src/app/Project/ProjectReducer.ts
+++ b/gui/src/app/Project/ProjectReducer.ts
@@ -25,7 +25,7 @@ export type ProjectReducerAction =
       type: "retitle";
       title: string;
     }
-  | { type: "setDataSource"; dataSource: DataSource | undefined }
+  | { type: "generateData"; content: string; dataSource: DataSource }
   | {
       type: "editFile";
       content: string;
@@ -71,9 +71,23 @@ const ProjectReducer = (s: ProjectDataModel, a: ProjectReducerAction) => {
     }
     case "commitFile": {
       const newState = { ...s };
+      if (a.filename === ProjectKnownFiles.DATAFILE) {
+        newState.meta = { ...s.meta, dataSource: undefined };
+      }
       newState[a.filename] = s.ephemera[a.filename];
       return newState;
     }
+    case "generateData": {
+      return {
+        ...s,
+        [ProjectKnownFiles.DATAFILE]: a.content,
+        ephemera: {
+          ...s.ephemera,
+          [ProjectKnownFiles.DATAFILE]: a.content,
+        },
+        meta: { ...s.meta, dataSource: a.dataSource },
+      };
+    }
     case "setSamplingOpts": {
       return { ...s, samplingOpts: { ...s.samplingOpts, ...a.opts } };
     }
@@ -83,9 +97,6 @@ const ProjectReducer = (s: ProjectDataModel, a: ProjectReducerAction) => {
     case "clear": {
       return initialDataModel;
     }
-    case "setDataSource": {
-      return { ...s, meta: { ...s.meta, dataSource: a.dataSource } };
-    }
     default:
       return unreachable(a);
   }
diff --git a/gui/src/app/Scripting/DataGeneration/useDataGenState.ts b/gui/src/app/Scripting/DataGeneration/useDataGenState.ts
index 25c74cc..830918b 100644
--- a/gui/src/app/Scripting/DataGeneration/useDataGenState.ts
+++ b/gui/src/app/Scripting/DataGeneration/useDataGenState.ts
@@ -1,5 +1,5 @@
 import { useCallback, useContext, useRef, useState } from "react";
-import { DataSource, ProjectKnownFiles } from "@SpCore/ProjectDataModel";
+import { DataSource } from "@SpCore/ProjectDataModel";
 import { writeConsoleOutToDiv } from "@SpScripting/OutputDivUtils";
 import { InterpreterStatus } from "@SpScripting/InterpreterTypes";
 import { ProjectContext } from "@SpCore/ProjectContextProvider";
@@ -21,13 +21,8 @@ const useDataGenState = (source: "python" | "r") => {
       if (dataJson !== lastData.current) {
         lastData.current = dataJson;
         update({
-          type: "editFile",
+          type: "generateData",
           content: dataJson,
-          filename: ProjectKnownFiles.DATAFILE,
-        });
-        update({ type: "commitFile", filename: ProjectKnownFiles.DATAFILE });
-        update({
-          type: "setDataSource",
           dataSource:
             source === "python"
               ? DataSource.GENERATED_BY_PYTHON
diff --git a/gui/src/app/pages/HomePage/HomePage.tsx b/gui/src/app/pages/HomePage/HomePage.tsx
index b1202c9..c407296 100644
--- a/gui/src/app/pages/HomePage/HomePage.tsx
+++ b/gui/src/app/pages/HomePage/HomePage.tsx
@@ -165,10 +165,6 @@ const DataEditor: FunctionComponent<{}> = () => {
       type: "commitFile",
       filename: ProjectKnownFiles.DATAFILE,
     });
-    update({
-      type: "setDataSource",
-      dataSource: undefined,
-    });
   }, [update]);
 
   return (
diff --git a/gui/test/app/Project/ProjectReducer.test.ts b/gui/test/app/Project/ProjectReducer.test.ts
index 04468cc..b868146 100644
--- a/gui/test/app/Project/ProjectReducer.test.ts
+++ b/gui/test/app/Project/ProjectReducer.test.ts
@@ -1,4 +1,5 @@
 import {
+  DataSource,
   getStringKnownFileKeys,
   initialDataModel,
   ProjectDataModel,
@@ -130,6 +131,7 @@ describe("Project reducer", () => {
     const initialState = {
       ...permanentFiles,
       ephemera: { ...ephemeralFiles },
+      meta: { dataSource: DataSource.GENERATED_BY_PYTHON },
     } as any as ProjectDataModel;
     const commitAction: ProjectReducerAction = {
       type: "commitFile",
@@ -143,6 +145,7 @@ describe("Project reducer", () => {
       expect(result[ProjectKnownFiles.DATAFILE]).toEqual(
         result.ephemera[ProjectKnownFiles.DATAFILE],
       );
+      expect(result.meta.dataSource).toBeUndefined();
     });
     test("Save action does not save non-chosen files", () => {
       const result = ProjectReducer(initialState, commitAction);
@@ -220,4 +223,24 @@ describe("Project reducer", () => {
       expect(result).toBe(initialDataModel);
     });
   });
+
+  describe("Generate data", () => {
+    test("Updates data file and ephemera with new data", () => {
+      const initialState = {
+        ...permanentFiles,
+        ephemera: { ...ephemeralFiles },
+        meta: { dataSource: DataSource.GENERATED_BY_R },
+      } as any as ProjectDataModel;
+      const newData = "generated data";
+      const generateAction: ProjectReducerAction = {
+        type: "generateData",
+        content: newData,
+        dataSource: DataSource.GENERATED_BY_PYTHON,
+      };
+      const result = ProjectReducer(initialState, generateAction);
+      expect(result[ProjectKnownFiles.DATAFILE]).toEqual(newData);
+      expect(result.ephemera[ProjectKnownFiles.DATAFILE]).toEqual(newData);
+      expect(result.meta.dataSource).toEqual(DataSource.GENERATED_BY_PYTHON);
+    });
+  });
 });