[autocomplete] Don't submit forms when committing freeSolo value with Enter key

packages/mui-material/src/Autocomplete/Autocomplete.test.js

@@ -3374,6 +3374,73 @@ describe('<Autocomplete />', () => {
       expect(handleChange.args[0][1]).to.equal('The');
     });
 
+    it('should prevent form submission when committing typed text over auto-highlighted match', async () => {
+      const handleChange = spy();
+      const handleSubmit = spy();
+      const options = ['The Shawshank Redemption', 'The Godfather'];
+      const { user } = render(
+        <div
+          onKeyDown={(event) => {
+            if (!event.defaultPrevented && event.key === 'Enter') {
+              handleSubmit();
+            }
+          }}
+        >
+          <Autocomplete
+            freeSolo
+            autoHighlight
+            openOnFocus
+            options={options}
+            onChange={handleChange}
+            renderInput={(params) => <TextField {...params} autoFocus />}
+          />
+        </div>,
+      );
+
+      await user.type(screen.getByRole('combobox'), 'The{Enter}');
+
+      expect(handleChange.callCount).to.equal(1);
+      expect(handleChange.args[0][1]).to.equal('The');
+      expect(handleSubmit.callCount).to.equal(0);
+
+      await user.keyboard('{Enter}');
+
+      expect(handleSubmit.callCount).to.equal(1);
+    });
+
+    it('should prevent form submission when committing edited selected text over value-highlighted match', async () => {
+      const handleChange = spy();
+      const handleSubmit = spy();
+      const options = ['The Shawshank Redemption', 'The Godfather'];
+      const { user } = render(
+        <div
+          onKeyDown={(event) => {
+            if (!event.defaultPrevented && event.key === 'Enter') {
+              handleSubmit();
+            }
+          }}
+        >
+          <Autocomplete
+            freeSolo
+            defaultValue="The Godfather"
+            options={options}
+            onChange={handleChange}
+            renderInput={(params) => <TextField {...params} autoFocus />}
+          />
+        </div>,
+      );
+
+      await user.keyboard('{Backspace}{Backspace}{Backspace}{Backspace}{Backspace}{Enter}');
+
+      expect(handleChange.callCount).to.equal(1);
+      expect(handleChange.args[0][1]).to.equal('The Godf');
+      expect(handleSubmit.callCount).to.equal(0);
+
+      await user.keyboard('{Enter}');
+
+      expect(handleSubmit.callCount).to.equal(1);
+    });
+
     it('should prefer typed text after editing a selected value', async () => {
       const handleChange = spy();
       const options = ['The Shawshank Redemption', 'The Godfather'];

packages/mui-material/src/useAutocomplete/useAutocomplete.js

@@ -1016,14 +1016,19 @@ function useAutocomplete(props) {
           }
           break;
         case 'Enter': {
-          // In freeSolo, only select the highlighted option if the user hasn't
-          // typed new text (inputPristine) or explicitly interacted with an option
-          // (keyboard, mouse, or touch — any non-null reason). This lets typed
-          // text win over a programmatic highlight (reason=null, e.g. from
-          // syncHighlightedIndex matching a previous value) while still honoring
-          // deliberate user interactions like hovering a suggestion then pressing Enter.
+          // In freeSolo, once the user has typed new text, Enter should commit that text instead
+          // of treating a programmatic highlight as an intentional selection. Programmatic
+          // highlights include autoHighlight and syncHighlightedIndex matching a previous value.
+          const hasProgrammaticHighlight =
+            popupOpen &&
+            highlightedIndexRef.current !== -1 &&
+            highlightReasonRef.current === null;
+          const shouldCommitFreeSoloOverProgrammaticHighlight =
+            freeSolo && !inputPristine && hasProgrammaticHighlight;
           const shouldSelectHighlighted =
-            !freeSolo || inputPristine || highlightReasonRef.current !== null;
+            !freeSolo || inputPristine || !hasProgrammaticHighlight;
+          const shouldPreventSubmitAfterFreeSoloCommit =
+            shouldCommitFreeSoloOverProgrammaticHighlight && !touchScrolledRef.current;
 
           if (
             highlightedIndexRef.current !== -1 &&
@@ -1053,8 +1058,8 @@ function useAutocomplete(props) {
               );
             }
           } else if (freeSolo && inputValue !== '' && inputValueIsSelectedValue === false) {
-            if (multiple) {
-              // Allow people to add new values before they submit the form.
+            if (multiple || shouldPreventSubmitAfterFreeSoloCommit) {
+              // Allow people to commit the freeSolo value before they submit the form.
               event.preventDefault();
             }
             selectNewValue(event, inputValue, 'createOption', 'freeSolo');