Field Assist is the one shortcut for everything bigger than a typo. Click into a text field, press ⌘., and Aha reads the field and works out what it needs. You don’t pick a mode. Write a request, some notes or a rough draft, and press the shortcut.
write a joke about foxes
Why did the fox bring a pencil to the henhouse? To draw a few chicks.
What it does with your text
| The field holds | Field Assist |
|---|---|
| A request, like “write a joke about foxes” or “reply saying I can’t make Friday” | Replaces it with the result. |
| A draft plus an instruction, like “…make this shorter” or “translate to Spanish” | Applies the instruction and drops it. |
| Notes or placeholders, like “Hello Ana, [intro paragraph]. I’d like to… etc” | Writes them out in full and keeps the rest. |
| An unfinished draft or email | Finishes it, adding a closing and sign-off to emails. |
| A finished message | Fixes mistakes only, or leaves it alone if there are none. |
| A question in a note or document only you will read | Answers it. |
| Nothing (an empty field) | Writes what belongs there, judging by the field and what’s around it. |
A message to someone else, like a chat reply or an email, is always treated as your draft. Field Assist never answers it on your behalf. Spelling, grammar and capitalization are fixed along the way.
With a selection
Select part of the text first and only the selection changes. Ordinary text is improved. If the selection is an instruction or a placeholder, it’s carried out to fit what’s around it.
In AI chats
In the prompt box of ChatGPT, Claude, Gemini, Perplexity and other AI chats, Field Assist polishes the prompt you’re about to send instead of answering it. “write a joke about foxes” becomes a clearer prompt, not a joke. A small note next to the preview says Polished your prompt for the AI.
Prefer the answer in the box? On the Rules page, open the AI chats tab and choose Answer in the box instead of Polish my prompt.
Keep or discard the preview
The result appears in the field with a blue highlight on just the parts that changed. Nothing is final until you decide.
| Key | What happens |
|---|---|
| ↩ | Keeps the new text. |
| Any other key | Keeps the new text, then types that key as usual. |
| esc, ⌫ or ⌦ | Restores your original text and selection. |
| Click elsewhere or switch apps | Keeps the new text. |
To stop a request that’s still thinking, press esc or choose Cancel Field Assist in the menu bar menu. After you keep a result, Revert Last Edit in the menu still puts your text back.
Settings
Find these in Settings › Field Assist.
- When the text is ready: Inline preview (the default) or Apply directly. With Apply directly, the result goes straight into the field. You still get a preview in terminals, in apps that hide their text, and when the result would replace most of a long text.
- Response length: Short, Medium (the default) or Long.
- Include surrounding context: on by default. Sends the app and window title, the site’s domain and nearby text such as labels, so replies fit where you’re writing. Turn it off to send only the field itself.
- Custom instructions: added to every request. For example: “Write in British English. Sign emails with ‘Best, Sam’.” For one kind of app or a single app, use Rules and apps.
Change the shortcut itself in Settings › Shortcuts.
Where it works, and where it doesn’t
Field Assist works in most apps that expose their text through macOS Accessibility, including Mail, Notes, Slack, browsers and AI chat apps. A few things to know:
- Terminals: the result is cut to one line and always previewed, so nothing runs until you press ↩.
- Very long fields: Field Assist continues at your cursor instead of rewriting the whole thing.
- If you keep typing while it’s thinking, Aha won’t overwrite your changes. It asks you to press the shortcut again.
Password, one-time-code and payment fields are always skipped, as are fields that look like they contain an API key or card number. Aha shows a short note instead and sends nothing.
Field Assist needs an Aha account or your own OpenRouter key, and each request counts toward your weekly allowance. See Account and usage.