fix(desktop): restore configured composer line breaks

desktop/src/components/chat/ChatInput.test.tsx

@@ -8,6 +8,8 @@ const viewportMocks = vi.hoisted(() => ({
 }))
 
 const originalOffsetWidth = Object.getOwnPropertyDescriptor(HTMLElement.prototype, 'offsetWidth')
+const originalRangeGetClientRects = Object.getOwnPropertyDescriptor(Range.prototype, 'getClientRects')
+const originalRangeGetBoundingClientRect = Object.getOwnPropertyDescriptor(Range.prototype, 'getBoundingClientRect')
 
 const mocks = vi.hoisted(() => ({
   create: vi.fn(),
@@ -239,8 +241,29 @@ describe('ChatInput file mentions', () => {
         },
       },
     })
-    // jsdom does not implement it, and the branch list scrolls its active row
-    // into view whenever the selection moves.
+    // jsdom does not implement these layout APIs. ProseMirror reads Range
+    // geometry when a newline transaction scrolls the new selection into view.
+    Object.defineProperties(Range.prototype, {
+      getClientRects: {
+        configurable: true,
+        value: () => [],
+      },
+      getBoundingClientRect: {
+        configurable: true,
+        value: () => ({
+          x: 0,
+          y: 0,
+          top: 0,
+          right: 0,
+          bottom: 0,
+          left: 0,
+          width: 0,
+          height: 0,
+          toJSON: () => ({}),
+        }),
+      },
+    })
+    // The branch list also scrolls its active row whenever the selection moves.
     Element.prototype.scrollIntoView = vi.fn()
     mocks.getGitInfo.mockResolvedValue({ branch: 'main', repoName: 'repo', workDir: '/repo', changedFiles: 0 })
     mocks.getRepositoryContext.mockResolvedValue(okRepositoryContext())
@@ -260,6 +283,16 @@ describe('ChatInput file mentions', () => {
     } else {
       Reflect.deleteProperty(HTMLElement.prototype, 'offsetWidth')
     }
+    if (originalRangeGetClientRects) {
+      Object.defineProperty(Range.prototype, 'getClientRects', originalRangeGetClientRects)
+    } else {
+      Reflect.deleteProperty(Range.prototype, 'getClientRects')
+    }
+    if (originalRangeGetBoundingClientRect) {
+      Object.defineProperty(Range.prototype, 'getBoundingClientRect', originalRangeGetBoundingClientRect)
+    } else {
+      Reflect.deleteProperty(Range.prototype, 'getBoundingClientRect')
+    }
   })
 
   // jsdom lays nothing out, so the composer column's width has to be stated.
@@ -1935,7 +1968,37 @@ describe('ChatInput file mentions', () => {
     expect(screen.getByTestId('chat-input-toolbar')).toHaveClass('-mx-3')
   })
 
-  it('uses Ctrl or Command Enter to send when that composer preference is selected', async () => {
+  it('uses Shift+Enter for a newline when Enter is the configured send shortcut', async () => {
+    useSettingsStore.setState({
+      chatSendBehavior: 'enter',
+    })
+
+    render(<ChatInput />)
+
+    await waitFor(() => {
+      expect(mocks.getGitInfo).toHaveBeenCalledWith(sessionId)
+    })
+
+    const input = getComposerElement()
+    setComposerText('firstsecond', 5)
+
+    fireEvent.keyDown(input, { key: 'Enter', shiftKey: true })
+
+    expect(mocks.wsSend).not.toHaveBeenCalled()
+    expect(getComposerText()).toBe('first\nsecond')
+
+    fireEvent.keyDown(input, { key: 'Enter' })
+    expect(mocks.wsSend).toHaveBeenCalledWith(sessionId, {
+      type: 'user_message',
+      content: 'first\nsecond',
+      attachments: [],
+    })
+  })
+
+  it.each([
+    ['Ctrl+Enter', { ctrlKey: true }],
+    ['Command+Enter', { metaKey: true }],
+  ])('uses Enter or Shift+Enter for newlines and %s to send when configured', async (_shortcut, modifier) => {
     useSettingsStore.setState({
       chatSendBehavior: 'modifierEnter',
     })
@@ -1947,15 +2010,20 @@ describe('ChatInput file mentions', () => {
     })
 
     const input = getComposerElement()
-    setComposerText('avoid accidental sends', 'avoid accidental sends'.length)
+    setComposerText('firstsecond', 5)
 
     fireEvent.keyDown(input, { key: 'Enter' })
     expect(mocks.wsSend).not.toHaveBeenCalled()
+    expect(getComposerText()).toBe('first\nsecond')
 
-    fireEvent.keyDown(input, { key: 'Enter', ctrlKey: true })
+    fireEvent.keyDown(input, { key: 'Enter', shiftKey: true })
+    expect(mocks.wsSend).not.toHaveBeenCalled()
+    expect(getComposerText()).toBe('first\n\nsecond')
+
+    fireEvent.keyDown(input, { key: 'Enter', ...modifier })
     expect(mocks.wsSend).toHaveBeenCalledWith(sessionId, {
       type: 'user_message',
-      content: 'avoid accidental sends',
+      content: 'first\n\nsecond',
       attachments: [],
     })
   })

desktop/src/components/chat/MentionComposer.tsx

@@ -20,7 +20,7 @@ import { EditorState, Plugin, PluginKey, TextSelection } from 'prosemirror-state
 import { EditorView } from 'prosemirror-view'
 import { keymap } from 'prosemirror-keymap'
 import { history, redo, undo } from 'prosemirror-history'
-import { baseKeymap } from 'prosemirror-commands'
+import { baseKeymap, splitBlock } from 'prosemirror-commands'
 import {
   buildComposerDoc,
   composerSchema,
@@ -139,6 +139,10 @@ export const MentionComposer = forwardRef<MentionComposerHandle, MentionComposer
             keymap({
               'Backspace': deleteAdjacentMentionAtom('backward'),
               'Delete': deleteAdjacentMentionAtom('forward'),
+              // Unlike a textarea, ProseMirror does not include Shift+Enter in
+              // its base keymap. Keep the composer's configured newline path
+              // explicit instead of relying on browser contenteditable behavior.
+              'Shift-Enter': splitBlock,
             }),
             keymap({ 'Mod-z': undo, 'Mod-y': redo, 'Mod-Shift-z': redo }),
             keymap(baseKeymap),