[Requests and ideas] Add text-to-speech playback for chat and Markdown content

**Mood:** 😊
**Category:** Requests and ideas

## Problem / opportunity

Users should be able to listen to Copilot app content aloud, not only read it visually. This would be useful for longer chat responses, Markdown content in the side panel, accessibility needs, and multitasking workflows.

## Proposed solution

Add text-to-speech playback support in the GitHub Copilot app for both:

- The main chat window
- The side panel, including Markdown-rendered content

## Playback controls

The playback UI should include standard media controls:

- Play
- Pause
- Rewind
- Playback speed adjustment

## Model selection

Playback should use the existing voice and text capabilities already available to the app where possible. Users should be able to choose from the available text-to-speech or voice models for playback.

## User value

This would make Copilot app content easier to consume in more contexts, especially when reviewing longer generated responses, reading Markdown documentation, or using the app hands-free.

## Open questions

- Should playback work on selected text, an entire chat response, or the full side-panel document?
- Should model or voice selection be global, per-session, or per-playback?
- Should rewind jump by a fixed interval, sentence, paragraph, or message?
- Should playback speed settings persist across sessions?

---
| Field | Value |
| --- | --- |
| App version | 0.2.32 |
| OS | macOS 26.5.1 |
| Theme | Fox |
| Path | /chat |
| Tenure | Week 4 |

## Note

I am aware this can already be done through a custom extension, but it would be great to have this functionality available out of the box without having to generate a custom canvas extension.

The issue names the /chat path but no implementation files, tests, or entry points. Start by locating the chat and side-panel content surfaces and reviewing the existing voice or text capabilities mentioned in the request. Done requires an agreed scope for content selection, model or voice choice, playback controls, and speed persistence, followed by working playback in both requested surfaces.

索引モデルが issue の本文から書いたものです。