fix(cli): Ctrl+C clears input, second Ctrl+C exits TUI

InputBar is now a controlled component — input state lives in app.tsx.
Ctrl+C when input has text clears it; Ctrl+C with empty input exits,
giving the standard two-press-to-quit behaviour expected in TUIs.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/cli/src/tui/app.tsx

@@ -73,6 +73,9 @@ export function TuiApp({
 
   const [sidebarSelectedIndex, setSidebarSelectedIndex] = useState(0);
 
+  // Controlled input state — held here so Ctrl+C can clear it
+  const [tuiInput, setTuiInput] = useState('');
+
   const handleLocalCommand = useCallback(
     (parsed: ParsedCommand) => {
       switch (parsed.command) {
@@ -153,9 +156,15 @@ export function TuiApp({
   );
 
   useInput((ch, key) => {
+    // Ctrl+C: clear input if non-empty; exit if already empty (second press)
     if (key.ctrl && ch === 'c') {
+      if (tuiInput) {
+        setTuiInput('');
+      } else {
         exit();
       }
+      return;
+    }
     // Ctrl+L: toggle sidebar (refresh on open)
     if (key.ctrl && ch === 'l') {
       const willOpen = !appMode.sidebarOpen;
@@ -260,6 +269,8 @@ export function TuiApp({
       )}
 
       <InputBar
+        value={tuiInput}
+        onChange={setTuiInput}
         onSubmit={socket.sendMessage}
         onSystemMessage={socket.addSystemMessage}
         onLocalCommand={handleLocalCommand}

packages/cli/src/tui/components/input-bar.tsx

@@ -1,12 +1,16 @@
-import React, { useState, useCallback } from 'react';
+import React, { useCallback } from 'react';
 import { Box, Text, useInput } from 'ink';
 import TextInput from 'ink-text-input';
 import type { ParsedCommand, CommandDef } from '@mosaic/types';
 import { parseSlashCommand, commandRegistry } from '../commands/index.js';
 import { CommandAutocomplete } from './command-autocomplete.js';
 import { useInputHistory } from '../hooks/use-input-history.js';
+import { useState } from 'react';
 
 export interface InputBarProps {
+  /** Controlled input value — caller owns the state */
+  value: string;
+  onChange: (val: string) => void;
   onSubmit: (value: string) => void;
   onSystemMessage?: (message: string) => void;
   onLocalCommand?: (parsed: ParsedCommand) => void;
@@ -18,6 +22,8 @@ export interface InputBarProps {
 }
 
 export function InputBar({
+  value: input,
+  onChange: setInput,
   onSubmit,
   onSystemMessage,
   onLocalCommand,
@@ -27,7 +33,6 @@ export function InputBar({
   placeholder: placeholderOverride,
   allCommands,
 }: InputBarProps) {
-  const [input, setInput] = useState('');
   const [showAutocomplete, setShowAutocomplete] = useState(false);
   const [autocompleteIndex, setAutocompleteIndex] = useState(0);
 
@@ -36,7 +41,8 @@ export function InputBar({
   // Determine which commands to show in autocomplete
   const availableCommands = allCommands ?? commandRegistry.getAll();
 
-  const handleChange = useCallback((value: string) => {
+  const handleChange = useCallback(
+    (value: string) => {
       setInput(value);
       if (value.startsWith('/')) {
         setShowAutocomplete(true);
@@ -44,7 +50,9 @@ export function InputBar({
       } else {
         setShowAutocomplete(false);
       }
-  }, []);
+    },
+    [setInput],
+  );
 
   const handleSubmit = useCallback(
     (value: string) => {
@@ -92,6 +100,7 @@ export function InputBar({
       isStreaming,
       connected,
       addToHistory,
+      setInput,
     ],
   );
 
@@ -116,7 +125,7 @@ export function InputBar({
       return true;
     }
     return false;
-  }, [showAutocomplete, input, availableCommands, autocompleteIndex]);
+  }, [showAutocomplete, input, availableCommands, autocompleteIndex, setInput]);
 
   useInput((ch, key) => {
     // Escape: hide autocomplete