fix: treat Option+Return as newline in multiline text inputs (#118)

* fix: treat Option+Return as newline in multiline text inputs

Currently only Shift+Return inserts a newline in multiline text areas
(like the chat input). Option+Return (Alt+Return) was treated the same
as plain Return, triggering the send action.

Add altKey checks alongside the existing shiftKey checks in both:
- ChatInput: skip send when altKey is held
- PromptInputTextarea: early-return (allow newline) when altKey is held

* test: add alt-enter multiline regression coverage

ui/goose2/src/features/chat/ui/ChatInput.tsx

@@ -279,7 +279,7 @@ export function ChatInput({
         }
       }
     }
-    if (e.key === "Enter" && !e.shiftKey) {
+    if (e.key === "Enter" && !e.shiftKey && !e.altKey) {
       e.preventDefault();
       handleSend();
     }

ui/goose2/src/features/chat/ui/__tests__/ChatInput.test.tsx

@@ -1,5 +1,5 @@
 import { describe, it, expect, vi } from "vitest";
-import { render, screen } from "@testing-library/react";
+import { fireEvent, render, screen } from "@testing-library/react";
 import userEvent from "@testing-library/user-event";
 import { useState } from "react";
 import { ChatInput } from "../ChatInput";
@@ -75,6 +75,23 @@ describe("ChatInput", () => {
     expect(onSend).not.toHaveBeenCalled();
   });
 
+  it("does not call onSend on Alt+Enter (newline)", async () => {
+    const onSend = vi.fn();
+    const user = userEvent.setup();
+    render(<ChatInput onSend={onSend} />);
+
+    const input = screen.getByRole("textbox");
+    await user.type(input, "hello");
+    const wasNotPrevented = fireEvent.keyDown(input, {
+      altKey: true,
+      key: "Enter",
+    });
+
+    expect(wasNotPrevented).toBe(true);
+    expect(onSend).not.toHaveBeenCalled();
+    expect(input).toHaveValue("hello");
+  });
+
   it("shows current model name in model picker", () => {
     render(
       <ChatInput

ui/goose2/src/shared/ui/ai-elements/prompt-input.test.tsx

@@ -0,0 +1,33 @@
+import { fireEvent, render, screen } from "@testing-library/react";
+import userEvent from "@testing-library/user-event";
+import { describe, expect, it, vi } from "vitest";
+import {
+  PromptInput,
+  PromptInputSubmit,
+  PromptInputTextarea,
+} from "./prompt-input";
+
+describe("PromptInputTextarea", () => {
+  it("does not submit on Alt+Enter and inserts a newline", async () => {
+    const onSubmit = vi.fn();
+    const user = userEvent.setup();
+
+    render(
+      <PromptInput onSubmit={onSubmit}>
+        <PromptInputTextarea />
+        <PromptInputSubmit />
+      </PromptInput>,
+    );
+
+    const input = screen.getByRole("textbox");
+    await user.type(input, "hello");
+    const wasNotPrevented = fireEvent.keyDown(input, {
+      altKey: true,
+      key: "Enter",
+    });
+
+    expect(wasNotPrevented).toBe(true);
+    expect(onSubmit).not.toHaveBeenCalled();
+    expect(input).toHaveValue("hello");
+  });
+});

ui/goose2/src/shared/ui/ai-elements/prompt-input.tsx

@@ -972,7 +972,7 @@ export const PromptInputTextarea = ({
         if (isComposing || e.nativeEvent.isComposing) {
           return;
         }
-        if (e.shiftKey) {
+        if (e.shiftKey || e.altKey) {
           return;
         }
         e.preventDefault();