feat(tui): add Esc key to cancel active prompt without exiting

src/frontends/tui/minimal.test.ts

@@ -29,10 +29,26 @@ function asAgent(value: unknown): NativeAgent {
 function minimalTuiPrivates(value: MinimalTui): {
   handleBackendCommand: (provider: string) => Promise<void>;
   handleModelCommand: (tier: string, providerModel?: string) => void;
+  prompt: (text: string) => Promise<string>;
+  rl: {
+    once: (event: string, cb: () => void) => void;
+    removeListener: (event: string, cb: () => void) => void;
+    question: (text: string, cb: (answer: string) => void) => void;
+    write: (data: string | null, key?: { ctrl?: boolean; name?: string }) => void;
+  };
+  activePromptCancel: (() => void) | null;
 } {
   return value as unknown as {
     handleBackendCommand: (provider: string) => Promise<void>;
     handleModelCommand: (tier: string, providerModel?: string) => void;
+    prompt: (text: string) => Promise<string>;
+    rl: {
+      once: (event: string, cb: () => void) => void;
+      removeListener: (event: string, cb: () => void) => void;
+      question: (text: string, cb: (answer: string) => void) => void;
+      write: (data: string | null, key?: { ctrl?: boolean; name?: string }) => void;
+    };
+    activePromptCancel: (() => void) | null;
   };
 }
 
@@ -270,3 +286,47 @@ describe('MinimalTui backend command', () => {
     }
   });
 });
+
+describe('MinimalTui prompt cancellation', () => {
+  it('cancels an active prompt without closing the TUI', async () => {
+    const mockSession = {
+      id: 'test',
+      getHistory: () => [],
+      addMessage: vi.fn(),
+      clear: vi.fn(),
+      replaceHistory: vi.fn(),
+    };
+
+    const tui = new MinimalTui({
+      session: asSession(mockSession),
+      modelClient: asRouter({}),
+      systemPrompt: 'test',
+    });
+
+    let onAnswer: ((answer: string) => void) | undefined;
+    const write = vi.fn((_: string | null, key?: { ctrl?: boolean; name?: string }) => {
+      if (key?.name === 'return') {
+        onAnswer?.('');
+      }
+    });
+
+    minimalTuiPrivates(tui).rl = {
+      once: vi.fn(),
+      removeListener: vi.fn(),
+      question: vi.fn((_text: string, cb: (answer: string) => void) => {
+        onAnswer = cb;
+      }),
+      write,
+    };
+
+    const promptPromise = minimalTuiPrivates(tui).prompt('Confirm? ');
+    expect(minimalTuiPrivates(tui).activePromptCancel).toBeTypeOf('function');
+
+    minimalTuiPrivates(tui).activePromptCancel?.();
+
+    await expect(promptPromise).resolves.toBe('');
+    expect(write).toHaveBeenCalledWith(null, { ctrl: true, name: 'u' });
+    expect(write).toHaveBeenCalledWith(null, { name: 'return' });
+    expect(minimalTuiPrivates(tui).activePromptCancel).toBeNull();
+  });
+});

src/frontends/tui/minimal.ts

@@ -75,6 +75,8 @@ export class MinimalTui {
   private totalUsage: TokenUsage = { inputTokens: 0, outputTokens: 0 };
   private currentHint = '';
   private lastLine = '';
+  private activePromptCancel: (() => void) | null = null;
+  private keypressHandler: ((char: string, key: readline.Key) => void) | null = null;
 
   constructor(private config: MinimalTuiConfig) {}
 
@@ -156,7 +158,12 @@ export class MinimalTui {
     }
 
     // Listen for line changes to show hints
-    process.stdin.on('keypress', () => {
+    this.keypressHandler = (_char: string, key: readline.Key) => {
+      if (key?.name === 'escape' && this.activePromptCancel) {
+        this.activePromptCancel();
+        return;
+      }
+
       // Small delay to let readline update the line
       setImmediate(() => {
         if (this.rl) {
@@ -167,7 +174,8 @@ export class MinimalTui {
           }
         }
       });
-    });
+    };
+    process.stdin.on('keypress', this.keypressHandler);
 
     // Enable keypress events
     if (process.stdin.isTTY) {
@@ -176,7 +184,7 @@ export class MinimalTui {
 
     console.log(getColoredBanner());
     console.log(`\n${colors.orange}${colors.bold}Flynn TUI${colors.reset} ${colors.dim}(minimal mode)${colors.reset}`);
-    console.log(`${colors.gray}Type /help for commands, /fullscreen for panel mode${colors.reset}\n`);
+    console.log(`${colors.gray}Type /help for commands, /fullscreen for panel mode, Esc to cancel prompts${colors.reset}\n`);
 
     await this.promptLoop();
   }
@@ -203,11 +211,35 @@ export class MinimalTui {
         resolve('');
         return;
       }
-      const onClose = () => resolve('');
+
-      this.rl.once('close', onClose);
+      let settled = false;
-      this.rl.question(promptText, (answer) => {
+      const finish = (answer: string) => {
+        if (settled) {
+          return;
+        }
+        settled = true;
+        this.activePromptCancel = null;
         this.rl?.removeListener('close', onClose);
         resolve(answer);
+      };
+
+      const onClose = () => finish('');
+      this.rl.once('close', onClose);
+      this.activePromptCancel = () => {
+        if (!this.rl) {
+          finish('');
+          return;
+        }
+        try {
+          this.rl.write(null, { ctrl: true, name: 'u' });
+          this.rl.write(null, { name: 'return' });
+        } catch {
+          finish('');
+        }
+      };
+
+      this.rl.question(promptText, (answer) => {
+        finish(answer);
       });
     });
   }
@@ -850,11 +882,14 @@ export class MinimalTui {
 
   stop(preserveStdin = false): void {
     this.running = false;
+    this.activePromptCancel = null;
     if (this.rl) {
       if (preserveStdin) {
         // Remove readline listeners but don't close stdin
         this.rl.removeAllListeners();
-        process.stdin.removeAllListeners('keypress');
+        if (this.keypressHandler) {
+          process.stdin.removeListener('keypress', this.keypressHandler);
+        }
         // Pause stdin so readline releases it
         process.stdin.pause();
       }
@@ -862,6 +897,9 @@ export class MinimalTui {
       this.rl = null;
     }
     // Clean up keypress listener
-    process.stdin.removeAllListeners('keypress');
+    if (this.keypressHandler) {
+      process.stdin.removeListener('keypress', this.keypressHandler);
+      this.keypressHandler = null;
+    }
   }
 }