[BUG] VS Code extension 2.1.259 (linux-x64): text selected in the chat panel copies nothing to the clipboard — regression, 2.1.258 works

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code (2.1.259 is where the bug reproduces; I have since pinned back to 2.1.258 to keep working)

What's Wrong?

In the VS Code extension's chat panel (the webview, not a terminal), selecting text and copying it puts nothing on the clipboard. Not garbled text, not partial text — zero characters.

This is a regression introduced in extension 2.1.259. Downgrading to 2.1.258 on the same machine, same session, same settings restores copying immediately.

Evidence that the clipboard receives zero characters rather than mangled ones: after copying a line of assistant output, pasting into the Claude Code prompt box left it in a state where the input was not recognized as containing text — the message could not be submitted until characters were typed by hand. When text was then typed and the message sent, the pasted portion arrived as nothing at all on the model's side.

Ruled out during diagnosis:

• Not Remote Control. It was connected; disconnecting it left the symptom unchanged.
• Not the fullscreen TUI renderer / mouse-capture selection path. The chat panel is a webview; there is no TUI here and /tui is unavailable in this environment. (Worth noting because the container also has DISPLAY=:3 set with no wl-copy/xclip/xsel installed, which is the precondition for #91306 — but that affects the terminal CLI, not the panel.)
• Not a stale window. Restarting VS Code did not help; downgrading the extension did.

What Should Happen?

Text selected in the chat panel should copy to the system clipboard with the standard OS shortcut, the same as any other selectable text in VS Code — as it did in 2.1.258 and earlier.

Error Messages/Logs

(no errors surfaced — the copy silently succeeds from the user's point of view)

Steps to Reproduce

1. Open VS Code connected to a Linux devcontainer (Remote-Containers), so the extension installs as anthropic.claude-code-<version>-linux-x64 under ~/.vscode-server/extensions/.
2. Ensure extension version 2.1.259 is installed.
3. Open the Claude Code chat panel and send any message so assistant output is rendered.
4. Select a portion of that output with the mouse.
5. Press Ctrl+C.
6. Paste anywhere — a GitHub comment box, the Claude Code prompt itself, a text editor. Nothing is pasted.
7. Extensions view → right-click Claude Code → Install Specific Version… → 2.1.258, reload the window, repeat steps 3-6. Copying now works.

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.258 (VS Code extension, linux-x64)

Claude Code Version

Extension: anthropic.claude-code 2.1.259, target platform linux-x64 (this is the version that matters here). Bundled CLI reports 2.1.237 (Claude Code).

Platform

Anthropic API

Operating System

Other Linux

Terminal/Shell

Other

Additional Information

Environment

• VS Code 1.136.1 (a44adf7f53e00964ab890f9f8758a334f1fc15bc, x64)
• Extension host: Linux x64 devcontainer via Remote-Containers; host is WSL2 (6.18.33.2-microsoft-standard-WSL2)
• Extension directory: ~/.vscode-server/extensions/anthropic.claude-code-2.1.259-linux-x64, auto-installed 2026-09-03 14:05 UTC — the breakage began at that point in an already-running workflow
• Interaction happens entirely in the extension's chat panel, not in a terminal

Scope not yet narrowed: I did not test whether copying is broken in other VS Code webviews (Settings UI, Markdown preview) in this same remote setup, so I can't say whether this is specific to the Claude panel or a webview-clipboard interaction that 2.1.259 newly exposes. Happy to run that test if it would help triage.

Possibly-related history: #58052 ("selected text in the transcript cannot be copied — nothing lands on the clipboard") and #46399 (panel copy grabs active-editor content instead) describe the same or adjacent symptoms in the chat panel. Both were closed as duplicates months ago and I could not find the issue they were duplicates of, nor any open issue tracking panel-copy behavior — hence this report rather than a comment on an existing one.

The clean bisect (2.1.259 broken → 2.1.258 working, nothing else changed) should make this cheap to localize in the diff between those two builds.