fix(client): prevent screen share audio loopback by default

[oliverlaz]

💡 Overview

When a user shares system audio while in a call, the OS-mixed system audio also includes the remote participants' voices coming out of the local speakers. This currently produces an unpleasant loopback for the remote speakers (they hear themselves played back through the screen share track).

This change updates the screen share audio defaults so AEC removes the call audio from the captured system audio by default, while preserving the rest (music, video, presentation audio).

📝 Implementation notes

• Flip echoCancellation to true in getScreenShareStream's default audio constraints
• Adds restrictOwnAudio for browsers that support it
• Change ScreenShareState's default audioBitrateProfile from MUSIC_HIGH_QUALITY to VOICE_HIGH_QUALITY. The previous default was inconsistent with what the capture path actually produces.
• The defaults still merge caller-supplied options.audio last, so any explicit override, including the constraints written by setAudioBitrateProfile(MUSIC_HIGH_QUALITY) continues to win, preserving HIFI music quality when the integrator opts in.

🎫 Ticket: https://linear.app/stream/issue/REACT-973/feedback-loop-issue-with-chromes-new-system-audio-sharing-feature

[changeset-bot]

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Latest commit: 64063e8

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[coderabbitai]

📝 Walkthrough

Walkthrough

Switches screen-share audio bitrate profile from MUSIC_HIGH_QUALITY to VOICE_HIGH_QUALITY, enables echo cancellation and restrictOwnAudio in getDisplayMedia audio constraints, and updates the corresponding test expectation.

Changes

Screen Share Audio Configuration

Layer / File(s)	Summary
Core Initialization packages/client/src/devices/ScreenShareState.ts	ScreenShareState constructor now passes AudioBitrateProfile.VOICE_HIGH_QUALITY to the base AudioDeviceManagerState instead of MUSIC_HIGH_QUALITY.
Media Constraints / Wiring packages/client/src/devices/devices.ts	getScreenShareStream audio constraints changed: echoCancellation set to true and restrictOwnAudio: true added (with @ts-expect-error for absent types); other audio constraint merging remains.
Tests packages/client/src/devices/__tests__/ScreenShareManager.test.ts	publishes screen share stream test updated to expect AudioBitrateProfile.VOICE_HIGH_QUALITY in the call.publish assertion.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

🐰 I hopped to tweak the sharing sound,
From music waves to voice profound,
Echoes softened, bitrate right,
Screened voices crisp and light 🎧

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: preventing screen share audio loopback by default.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description check	✅ Passed	The pull request description provides a clear overview of the problem, implementation details, and the ticket reference. All required template sections are present and well-filled.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch worktree-screenshare-audio

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