diff --git a/packages/cli/src/ui/AppContainer.test.tsx b/packages/cli/src/ui/AppContainer.test.tsx
index 78e9b875aa..cee6e918d7 100644
--- a/packages/cli/src/ui/AppContainer.test.tsx
+++ b/packages/cli/src/ui/AppContainer.test.tsx
@@ -1450,6 +1450,7 @@ describe('AppContainer State Management', () => {
             meta: false,
             shift: false,
             paste: false,
+            insertable: false,
             sequence: '\x13',
           });
         });
@@ -1476,6 +1477,7 @@ describe('AppContainer State Management', () => {
               meta: false,
               shift: false,
               paste: false,
+              insertable: false,
               sequence: '\x13',
             });
           });
@@ -1490,6 +1492,7 @@ describe('AppContainer State Management', () => {
               meta: false,
               shift: false,
               paste: false,
+              insertable: true,
               sequence: 'a',
             });
           });
@@ -1510,6 +1513,7 @@ describe('AppContainer State Management', () => {
               meta: false,
               shift: false,
               paste: false,
+              insertable: false,
               sequence: '\x13',
             });
           });
@@ -1525,6 +1529,7 @@ describe('AppContainer State Management', () => {
               meta: false,
               shift: false,
               paste: false,
+              insertable: true,
               sequence: 'a',
             });
           });
diff --git a/packages/cli/src/ui/components/ModelDialog.test.tsx b/packages/cli/src/ui/components/ModelDialog.test.tsx
index 2ec9b21c32..5c8338c604 100644
--- a/packages/cli/src/ui/components/ModelDialog.test.tsx
+++ b/packages/cli/src/ui/components/ModelDialog.test.tsx
@@ -188,6 +188,7 @@ describe('<ModelDialog />', () => {
       meta: false,
       shift: false,
       paste: false,
+      insertable: false,
       sequence: '',
     });
     expect(props.onClose).toHaveBeenCalledTimes(1);
@@ -198,6 +199,7 @@ describe('<ModelDialog />', () => {
       meta: false,
       shift: false,
       paste: false,
+      insertable: true,
       sequence: '',
     });
     expect(props.onClose).toHaveBeenCalledTimes(1);
diff --git a/packages/cli/src/ui/components/shared/text-buffer.test.ts b/packages/cli/src/ui/components/shared/text-buffer.test.ts
index 5ff088a3f0..02bdd9d533 100644
--- a/packages/cli/src/ui/components/shared/text-buffer.test.ts
+++ b/packages/cli/src/ui/components/shared/text-buffer.test.ts
@@ -977,6 +977,7 @@ describe('useTextBuffer', () => {
           meta: false,
           shift: false,
           paste: false,
+          insertable: true,
           sequence: 'h',
         }),
       );
@@ -987,6 +988,7 @@ describe('useTextBuffer', () => {
           meta: false,
           shift: false,
           paste: false,
+          insertable: true,
           sequence: 'i',
         }),
       );
@@ -1004,6 +1006,7 @@ describe('useTextBuffer', () => {
           meta: false,
           shift: false,
           paste: false,
+          insertable: true,
           sequence: '\r',
         }),
       );
@@ -1021,6 +1024,7 @@ describe('useTextBuffer', () => {
           meta: false,
           shift: false,
           paste: false,
+          insertable: false,
           sequence: '\t',
         }),
       );
@@ -1038,6 +1042,7 @@ describe('useTextBuffer', () => {
           meta: false,
           shift: true,
           paste: false,
+          insertable: false,
           sequence: '\u001b[9;2u',
         }),
       );
@@ -1060,6 +1065,7 @@ describe('useTextBuffer', () => {
           meta: false,
           shift: false,
           paste: false,
+          insertable: false,
           sequence: '\x7f',
         }),
       );
@@ -1084,6 +1090,7 @@ describe('useTextBuffer', () => {
           meta: false,
           shift: false,
           paste: false,
+          insertable: false,
           sequence: '\x7f',
         });
         result.current.handleInput({
@@ -1092,6 +1099,7 @@ describe('useTextBuffer', () => {
           meta: false,
           shift: false,
           paste: false,
+          insertable: false,
           sequence: '\x7f',
         });
         result.current.handleInput({
@@ -1100,6 +1108,7 @@ describe('useTextBuffer', () => {
           meta: false,
           shift: false,
           paste: false,
+          insertable: false,
           sequence: '\x7f',
         });
       });
@@ -1159,6 +1168,7 @@ describe('useTextBuffer', () => {
           meta: false,
           shift: false,
           paste: false,
+          insertable: false,
           sequence: '\x1b[D',
         }),
       ); // cursor [0,1]
@@ -1170,6 +1180,7 @@ describe('useTextBuffer', () => {
           meta: false,
           shift: false,
           paste: false,
+          insertable: false,
           sequence: '\x1b[C',
         }),
       ); // cursor [0,2]
@@ -1189,6 +1200,7 @@ describe('useTextBuffer', () => {
           meta: false,
           shift: false,
           paste: false,
+          insertable: true,
           sequence: textWithAnsi,
         }),
       );
@@ -1206,6 +1218,7 @@ describe('useTextBuffer', () => {
           meta: false,
           shift: true,
           paste: false,
+          insertable: true,
           sequence: '\r',
         }),
       ); // Simulates Shift+Enter in VSCode terminal
@@ -1410,6 +1423,7 @@ Contrary to popular belief, Lorem Ipsum is not simply random text. It has roots
       meta: false,
       shift: false,
       paste: false,
+      insertable: true,
       sequence,
     });
 
@@ -1468,6 +1482,7 @@ Contrary to popular belief, Lorem Ipsum is not simply random text. It has roots
           meta: false,
           shift: false,
           paste: false,
+          insertable: true,
           sequence: largeTextWithUnsafe,
         }),
       );
@@ -1502,6 +1517,7 @@ Contrary to popular belief, Lorem Ipsum is not simply random text. It has roots
           meta: false,
           shift: false,
           paste: false,
+          insertable: true,
           sequence: largeTextWithAnsi,
         }),
       );
@@ -1526,6 +1542,7 @@ Contrary to popular belief, Lorem Ipsum is not simply random text. It has roots
           meta: false,
           shift: false,
           paste: false,
+          insertable: true,
           sequence: emojis,
         }),
       );
@@ -1717,12 +1734,35 @@ Contrary to popular belief, Lorem Ipsum is not simply random text. It has roots
           meta: false,
           shift: false,
           paste: false,
+          insertable: true,
           sequence: '\r',
         }),
       );
       expect(getBufferState(result).lines).toEqual(['']);
     });
 
+    it('should not print anything for function keys when singleLine is true', () => {
+      const { result } = renderHook(() =>
+        useTextBuffer({
+          viewport,
+          isValidPath: () => false,
+          singleLine: true,
+        }),
+      );
+      act(() =>
+        result.current.handleInput({
+          name: 'f1',
+          ctrl: false,
+          meta: false,
+          shift: false,
+          paste: false,
+          insertable: false,
+          sequence: '\u001bOP',
+        }),
+      );
+      expect(getBufferState(result).lines).toEqual(['']);
+    });
+
     it('should strip newlines from pasted text when singleLine is true', () => {
       const { result } = renderHook(() =>
         useTextBuffer({
diff --git a/packages/cli/src/ui/components/shared/text-buffer.ts b/packages/cli/src/ui/components/shared/text-buffer.ts
index b44485cb0c..70f30abc03 100644
--- a/packages/cli/src/ui/components/shared/text-buffer.ts
+++ b/packages/cli/src/ui/components/shared/text-buffer.ts
@@ -17,6 +17,7 @@ import {
   stripUnsafeCharacters,
   getCachedStringWidth,
 } from '../../utils/textUtils.js';
+import type { Key } from '../../contexts/KeypressContext.js';
 import type { VimAction } from './vim-buffer-actions.js';
 import { handleVimAction } from './vim-buffer-actions.js';
 
@@ -1907,14 +1908,7 @@ export function useTextBuffer({
   );
 
   const handleInput = useCallback(
-    (key: {
-      name: string;
-      ctrl: boolean;
-      meta: boolean;
-      shift: boolean;
-      paste: boolean;
-      sequence: string;
-    }): void => {
+    (key: Key): void => {
       const { sequence: input } = key;
 
       if (key.paste) {
@@ -1964,7 +1958,7 @@ export function useTextBuffer({
       else if (key.name === 'delete' || (key.ctrl && key.name === 'd')) del();
       else if (key.ctrl && !key.shift && key.name === 'z') undo();
       else if (key.ctrl && key.shift && key.name === 'z') redo();
-      else if (input && !key.ctrl && !key.meta && key.name !== 'tab') {
+      else if (key.insertable) {
         insert(input, { paste: key.paste });
       }
     },
@@ -2266,14 +2260,7 @@ export interface TextBuffer {
   /**
    * High level "handleInput" – receives what Ink gives us.
    */
-  handleInput: (key: {
-    name: string;
-    ctrl: boolean;
-    meta: boolean;
-    shift: boolean;
-    paste: boolean;
-    sequence: string;
-  }) => void;
+  handleInput: (key: Key) => void;
   /**
    * Opens the current buffer contents in the user's preferred terminal text
    * editor ($VISUAL or $EDITOR, falling back to "vi").  The method blocks
diff --git a/packages/cli/src/ui/contexts/KeypressContext.tsx b/packages/cli/src/ui/contexts/KeypressContext.tsx
index a48231a463..1d1fcbbcde 100644
--- a/packages/cli/src/ui/contexts/KeypressContext.tsx
+++ b/packages/cli/src/ui/contexts/KeypressContext.tsx
@@ -224,6 +224,7 @@ function bufferPaste(
           meta: false,
           shift: false,
           paste: true,
+          insertable: true,
           sequence: buffer,
         });
       }
@@ -273,6 +274,7 @@ function* emitKeys(
     let meta = false;
     let shift = false;
     let code = undefined;
+    let insertable = false;
 
     if (ch === ESC) {
       escaped = true;
@@ -455,6 +457,7 @@ function* emitKeys(
     } else if (ch === ' ') {
       name = 'space';
       meta = escaped;
+      insertable = true;
     } else if (!escaped && ch <= '\x1a') {
       // ctrl+letter
       name = String.fromCharCode(ch.charCodeAt(0) + 'a'.charCodeAt(0) - 1);
@@ -464,6 +467,7 @@ function* emitKeys(
       name = ch.toLowerCase();
       shift = /^[A-Z]$/.exec(ch) !== null;
       meta = escaped;
+      insertable = true;
     } else if (MAC_ALT_KEY_CHARACTER_MAP[ch] && process.platform === 'darwin') {
       name = MAC_ALT_KEY_CHARACTER_MAP[ch];
       meta = true;
@@ -479,12 +483,16 @@ function* emitKeys(
         meta,
         shift,
         paste: false,
+        insertable: false,
         sequence: ESC,
       });
     } else if (escaped) {
       // Escape sequence timeout
       name = ch.length ? undefined : 'escape';
       meta = true;
+    } else {
+      // Any other character is considered printable.
+      insertable = true;
     }
 
     if (
@@ -497,6 +505,7 @@ function* emitKeys(
         meta,
         shift,
         paste: false,
+        insertable,
         sequence,
       });
     }
@@ -510,6 +519,7 @@ export interface Key {
   meta: boolean;
   shift: boolean;
   paste: boolean;
+  insertable: boolean;
   sequence: string;
 }
 
diff --git a/packages/cli/src/ui/hooks/useKeypress.test.tsx b/packages/cli/src/ui/hooks/useKeypress.test.tsx
index f849a86a25..6a063f35fc 100644
--- a/packages/cli/src/ui/hooks/useKeypress.test.tsx
+++ b/packages/cli/src/ui/hooks/useKeypress.test.tsx
@@ -38,7 +38,7 @@ class MockStdin extends EventEmitter {
   }
 }
 
-describe(`useKeypress with useKitty=%s`, () => {
+describe(`useKeypress`, () => {
   let stdin: MockStdin;
   const mockSetRawMode = vi.fn();
   const onKeypress = vi.fn();
@@ -144,6 +144,7 @@ describe(`useKeypress with useKitty=%s`, () => {
         meta: false,
         shift: false,
         paste: true,
+        insertable: true,
         sequence: pasteText,
       });
     });
@@ -281,6 +282,7 @@ describe(`useKeypress with useKitty=%s`, () => {
         meta: false,
         shift: false,
         paste: true,
+        insertable: true,
         sequence: pasteText,
       });
     });
diff --git a/packages/cli/src/ui/hooks/useSelectionList.test.tsx b/packages/cli/src/ui/hooks/useSelectionList.test.tsx
index 7964bf591f..b4b203e72d 100644
--- a/packages/cli/src/ui/hooks/useSelectionList.test.tsx
+++ b/packages/cli/src/ui/hooks/useSelectionList.test.tsx
@@ -62,6 +62,7 @@ describe('useSelectionList', () => {
           meta: false,
           shift: options.shift ?? false,
           paste: false,
+          insertable: false,
         };
         activeKeypressHandler(key);
       } else {
@@ -331,6 +332,7 @@ describe('useSelectionList', () => {
           meta: false,
           shift: false,
           paste: false,
+          insertable: true,
         };
         handler(key);
       };
@@ -380,6 +382,7 @@ describe('useSelectionList', () => {
             meta: false,
             shift: false,
             paste: false,
+            insertable: false,
           };
           handler(key);
         };
diff --git a/packages/cli/src/ui/hooks/vim.test.tsx b/packages/cli/src/ui/hooks/vim.test.tsx
index d3cec9cc13..3f6ae1f90b 100644
--- a/packages/cli/src/ui/hooks/vim.test.tsx
+++ b/packages/cli/src/ui/hooks/vim.test.tsx
@@ -40,6 +40,7 @@ const createKey = (partial: Partial<Key>): Key => ({
   meta: partial.meta || false,
   shift: partial.shift || false,
   paste: partial.paste || false,
+  insertable: partial.insertable || false,
   ...partial,
 });
 
diff --git a/packages/cli/src/ui/hooks/vim.ts b/packages/cli/src/ui/hooks/vim.ts
index d8d5ab38d2..dc3344a201 100644
--- a/packages/cli/src/ui/hooks/vim.ts
+++ b/packages/cli/src/ui/hooks/vim.ts
@@ -313,6 +313,7 @@ export function useVim(buffer: TextBuffer, onSubmit?: (value: string) => void) {
       meta: key.meta || false,
       shift: key.shift || false,
       paste: key.paste || false,
+      insertable: key.insertable || false,
     }),
     [],
   );
diff --git a/packages/cli/src/ui/keyMatchers.test.ts b/packages/cli/src/ui/keyMatchers.test.ts
index baaa88dbff..be028f5c02 100644
--- a/packages/cli/src/ui/keyMatchers.test.ts
+++ b/packages/cli/src/ui/keyMatchers.test.ts
@@ -17,6 +17,7 @@ describe('keyMatchers', () => {
     meta: false,
     shift: false,
     paste: false,
+    insertable: false,
     sequence: name,
     ...mods,
   });