fix(text-buffer): correct word deletion logic for trailing spaces (Ctrl+Backspace) (#131)

## Description
This fix resolves a bug where Ctrl+Backspace (hex 0x17) deletes the
entire line when the cursor is positioned after a trailing space.

## Problem
When the user has a line like "I want you to refactor my view " (with a
space at the end) and the cursor is after that space, Ctrl+Backspace
deletes the entire line instead of just removing the word "view".

## Solution
- Added a check to detect if the cursor is after spaces
- Modified the logic to delete only one space at a time in this case
- Added a unit test to verify this behavior

## Tests
All tests pass, including the new test that verifies the corrected
behavior.

---------

Signed-off-by: Alpha Diop <alphakhoss@gmail.com>
Co-authored-by: Thibault Sottiaux <tibo@openai.com>

codex-cli/src/text-buffer.ts

@@ -443,17 +443,29 @@ export default class TextBuffer {
     const line = this.line(this.cursorRow);
     const arr = toCodePoints(line);
 
-    // Step 1 – skip over any separators sitting *immediately* to the left of
-    // the caret so that consecutive deletions wipe runs of whitespace first
-    // then words.
+    // If the cursor is just after a space (or several spaces), we only delete the separators
+    // then, on the next call, the previous word. We should never delete the entire line.
     let start = this.cursorCol;
-    while (start > 0 && !isWordChar(arr[start - 1])) {
-      start--;
+    let onlySpaces = true;
+    for (let i = 0; i < start; i++) {
+      if (isWordChar(arr[i])) {
+        onlySpaces = false;
+        break;
+      }
     }
 
-    // Step 2 – now skip the word characters themselves.
-    while (start > 0 && isWordChar(arr[start - 1])) {
+    // If the line contains only spaces up to the cursor, delete just one space
+    if (onlySpaces && start > 0) {
       start--;
+    } else {
+      // Step 1 – skip over any separators sitting *immediately* to the left of the caret
+      while (start > 0 && !isWordChar(arr[start - 1])) {
+        start--;
+      }
+      // Step 2 – skip the word characters themselves
+      while (start > 0 && isWordChar(arr[start - 1])) {
+        start--;
+      }
     }
 
     this.lines[this.cursorRow] =