[BUG] Desktop app (Code tab): voice dictation always appends to end of prompt instead of inserting at cursor / replacing selection

Environment: Claude desktop app 2.31226.1 (Code tab), macOS 27.0.1

What's wrong

Voice dictation in the Code tab prompt box always adds new speech to the end of the text and ignores the cursor. You can't dictate into the middle of a prompt or speak a replacement for a selected word.

Steps to reproduce

1. In the Code tab, tap the voice icon and dictate a sentence.
2. Pause, then click to put the cursor somewhere in the middle of that sentence (or double-click a word to select it).
3. Keep dictating.

Expected

New speech goes in at the cursor, or replaces the selected text, the way dictation works in macOS and iOS text fields.

Actual

New speech is always added to the end of the prompt, wherever the cursor is and whether or not text is selected.

Why it matters

Speech-to-text often mishears a word. The natural fix is to double-click the wrong word and say it again. Right now you have to switch to the keyboard, or delete the text and dictate it again.

Related

• #98502 asks for terminal (TUI) tap mode to insert the transcript at the cursor. This issue is about the desktop app's prompt box.