feat(app): gate return-key submit icon to new workspace composer

The new-workspace composer is a one-shot "create" submit, not a chat send, so
a return-key glyph reads more accurately there than an arrow. Add a submitIcon
prop on Composer/MessageInput (defaulting to "arrow") and opt NewWorkspace
into "return".

packages/app/src/components/composer.test.tsx

@@ -176,6 +176,7 @@ vi.mock("lucide-react-native", () => {
   const createIcon = (name: string) => (props: Record<string, unknown>) =>
     React.createElement("span", { ...props, "data-icon": name });
   return {
+    ArrowUp: createIcon("ArrowUp"),
     CornerDownLeft: createIcon("CornerDownLeft"),
     Square: createIcon("Square"),
     Pencil: createIcon("Pencil"),

packages/app/src/components/composer.tsx

@@ -100,6 +100,7 @@ interface ComposerProps {
   allowEmptySubmit?: boolean;
   /** Optional accessibility label for the primary submit button. */
   submitButtonAccessibilityLabel?: string;
+  submitIcon?: "arrow" | "return";
   /** Externally controlled loading state. When true, disables the submit button. */
   isSubmitLoading?: boolean;
   submitBehavior?: "clear" | "preserve-and-lock";
@@ -142,6 +143,7 @@ export function Composer({
   hasExternalContent = false,
   allowEmptySubmit = false,
   submitButtonAccessibilityLabel,
+  submitIcon = "arrow",
   isSubmitLoading = false,
   submitBehavior = "clear",
   blurOnSubmit = false,
@@ -930,6 +932,7 @@ export function Composer({
               hasExternalContent={hasExternalContent}
               allowEmptySubmit={allowEmptySubmit}
               submitButtonAccessibilityLabel={submitButtonAccessibilityLabel}
+              submitIcon={submitIcon}
               isSubmitDisabled={isProcessing || isSubmitLoading}
               isSubmitLoading={isProcessing || isSubmitLoading}
               attachments={selectedAttachments}

packages/app/src/components/message-input.test.tsx

@@ -49,6 +49,7 @@ vi.mock("lucide-react-native", () => {
   const createIcon = (name: string) => (props: Record<string, unknown>) =>
     React.createElement("span", { ...props, "data-icon": name });
   return {
+    ArrowUp: createIcon("ArrowUp"),
     Mic: createIcon("Mic"),
     MicOff: createIcon("MicOff"),
     CornerDownLeft: createIcon("CornerDownLeft"),
@@ -226,18 +227,27 @@ afterEach(() => {
   vi.unstubAllGlobals();
 });
 
-function renderMessageInput(menuItems: AttachmentMenuItem[]) {
+interface RenderMessageInputOptions {
+  value?: string;
+  submitIcon?: "arrow" | "return";
+}
+
+function renderMessageInput(
+  menuItems: AttachmentMenuItem[],
+  { value = "", submitIcon }: RenderMessageInputOptions = {},
+) {
   act(() => {
     root?.render(
       <MessageInput
-        value=""
+        value={value}
         onChangeText={vi.fn()}
         onSubmit={vi.fn()}
         attachments={[]}
         cwd="/repo"
         attachmentMenuItems={menuItems}
         client={{ isConnected: true } as never}
-        isAgentRunning
+        isAgentRunning={false}
+        submitIcon={submitIcon}
         onQueue={vi.fn()}
       />,
     );
@@ -302,4 +312,16 @@ describe("MessageInput attachments", () => {
 
     expect(queryAllByAriaLabel("Queue message")).toHaveLength(0);
   });
+
+  it("uses ArrowUp by default and CornerDownLeft when return submit icon is requested", () => {
+    renderMessageInput([], { value: "Send this" });
+
+    expect(document.querySelectorAll('[data-icon="ArrowUp"]')).toHaveLength(1);
+    expect(document.querySelectorAll('[data-icon="CornerDownLeft"]')).toHaveLength(0);
+
+    renderMessageInput([], { value: "Create this", submitIcon: "return" });
+
+    expect(document.querySelectorAll('[data-icon="ArrowUp"]')).toHaveLength(0);
+    expect(document.querySelectorAll('[data-icon="CornerDownLeft"]')).toHaveLength(1);
+  });
 });

packages/app/src/components/message-input.tsx

@@ -20,7 +20,7 @@ import {
   forwardRef,
 } from "react";
 import { StyleSheet, useUnistyles } from "react-native-unistyles";
-import { Mic, MicOff, CornerDownLeft, Plus, Square } from "lucide-react-native";
+import { ArrowUp, Mic, MicOff, CornerDownLeft, Plus, Square } from "lucide-react-native";
 import Animated, { useSharedValue, useAnimatedStyle, withTiming } from "react-native-reanimated";
 import { useDictation } from "@/hooks/use-dictation";
 import { DictationOverlay } from "./dictation-controls";
@@ -85,6 +85,7 @@ export interface MessageInputProps {
   allowEmptySubmit?: boolean;
   /** Optional accessibility label for the primary submit button. */
   submitButtonAccessibilityLabel?: string;
+  submitIcon?: "arrow" | "return";
   isSubmitDisabled?: boolean;
   isSubmitLoading?: boolean;
   attachments: ComposerAttachment[];
@@ -217,6 +218,7 @@ export const MessageInput = forwardRef<MessageInputRef, MessageInputProps>(funct
     hasExternalContent = false,
     allowEmptySubmit = false,
     submitButtonAccessibilityLabel,
+    submitIcon = "arrow",
     isSubmitDisabled = false,
     isSubmitLoading = false,
     attachments,
@@ -1180,8 +1182,10 @@ export const MessageInput = forwardRef<MessageInputRef, MessageInputProps>(funct
                 >
                   {isSubmitLoading ? (
                     <ActivityIndicator size="small" color="white" />
-                  ) : (
+                  ) : submitIcon === "return" ? (
                     <CornerDownLeft size={buttonIconSize} color="white" />
+                  ) : (
+                    <ArrowUp size={buttonIconSize} color="white" />
                   )}
                 </TooltipTrigger>
                 <TooltipContent side="top" align="center" offset={8}>