Feature request: "Add to chat" annotations for replying to parts of past responses #4903

What I'd like

When I highlight text in one of Copilot's earlier responses, I'd love an "Add to chat" button that lets me attach a quick comment to that exact passage. ChatGPT's desktop app has this, and it's become one of my favorite little timesavers.

How it works in ChatGPT

1. Highlight any part of a past response, and an "Add to chat" button pops up.
2. Click it, and a small "Add an optional comment" field appears right by the selection (with a mic button for voice).
3. The highlight gets a numbered marker in the thread, so I can see what I've flagged until I send.
4. The composer shows a chip like "1 annotation" instead of stuffing the quote and my reply into the input field.
5. When I send my next message, the annotations go with it. A lot of the time I don't need to type anything else.

Why it matters

Right now, reacting to specific parts of a long response means copying quotes, pasting them into the composer, and formatting everything so the model knows what I'm pointing at. It's slow and it clutters the prompt. Annotations keep the composer clean and make it easy to give pointed feedback on several spots at once ("yes to this," "change this," "why this?").

I think this would be especially handy in agent sessions, where responses run long and I usually want to react to a few specific lines.

How this compares to Quote

Copilot already has a Quote option when you select text, which is a similar idea. The catch is that it drops the selected text straight into the prompt field, so the input still gets cluttered. I'm also never quite sure whether my reply should go above or below the quote, and the formatting feels a bit off. Turning Quote into something closer to ChatGPT's annotations (attached to the prompt, but outside the input field) would make it a lot cleaner.

Nice to have

• Numbered references to the annotations stay visible in the sent message, so the thread history is easy to follow.
• A way to edit or remove an annotation before sending.
• Multiple annotations across different past responses in a single prompt.