[CRITICAL BUG] Claude Code extension ruin entire 'google antigravity IDE - Activity Items Icon list' (Antigravity - lacking Secondary Sidebar support in Lower OSS version)

Bug Description
[ CRITICAL ISSUE ] Claude Code for VS Code Extension ruin other activity Items Icon list ... in Antigravity

I already made a comment at #14152, as referenced, made new issue.

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In google Antigravity IDE latest version (VS Code OSS v1.104)
After install 'Claude Code for VS Code' Extension latest version (2.1.7) and re-start
--> suddenly, left panel (Primary activity items Icons - the other extension like aws, gitlens, gitgraph, github pull/request, etc.) = disappeared --> moved into antigravity's left explorer menu.
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Note ; this is still unresolved in Extension v2.1.19 (Jan 24th, 2026)

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So,

I simply disabled the 'Claude Code for VS Code' Extension in Antigravity,
and re-start Antigravity IDE, every icon suddenly get back in the Activity Items icon area (no more list in explorer)
I enabled 'Claude Code for VS Code' Extension, re-start --> Icon has be gone again.

Analysis

1. 'Claude Code for VS Code Extension' is designed to run on the latest VS Code. (If you check the file in the extension's installation directory, you'll find a 'secondary sidebar' entry in the package.json file.)

1. VS Code latest version 1.108 vs. Antigravity (VS Code OSS v1.104) --> Antigravity currently doesn't support 'the Secondary Sidebar' feature (old version). FYI, However, although it is not supported in the antigravity message, there is actually a secondary panel on the right side (although it malfunctions), and the Antigravity's built-in chat panel is actually the secondary panel.

1. However, during the Claude Code Extension installation process, there's no clear indication of incompatibility or errors with VS Code OSS versions lower than a specific one.

Solution ##

Browse the Claude Code Extension installation folder and delete the secondary sidebar definition in package.json. ----> No error occurs --> The problem disappears completely. --> If you add an exception handling function within the 'Claude Code for VS Code Extension' to check if the current IDE version (VSCode OSS Version) is an older version that supports secondary sidebar, the error will be resolved. (As a result, errors with cursor and antigravity will disappear.)

Claude Code for VS Code Extension v2.1.7

a. Delete 'secondary sidebar' related ... two section in intalled extension's files:

Windows ~\.antigravity\extentions\anthropic.claude-code-2.1.7-win32-x64\package.json
Ubuntu ~/.antigravity-server/extensions/anthropic.claude-code-2.1.7-linux-x64/package.json

'secondarySidebar' [ ...... ]

<img width="1079" height="1316" alt="Image" src="https://github.com/user-attachments/assets/a12da719-a71d-4821-8d00-0c2e8c9d7a04" />

b. re-start antigravity
c. left activity items icon is back form explorer (Primary sidebar activity items...)
d. But a few days later, If the CC extension is updated without this fix, this error will occur again.

Caution

If there is another extension that similarly includes secondary sidebar related content in its package.json --> When that extension will be activated after installation --> So the same error is expected to occur in Antigravity, cursor, etc.

Environment Info

• Platform: windows11, WSL:ubuntu --> Antigravity IDE (VS Code OSS version 1.104 fork) <-- !!
• Claude Code for VS Code Extension Version: 2.1.7 (latest)
• Feedback ID: 616b943d-9cb5-4de1-a9c3-3d8366222f41

Errors

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