[BUG] Regression: VS Code "Manage Plugins" shows "No plugins available" with multiple marketplaces (64KB JSON truncation, previously fixed in 2.1.117 — refs #47237)

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

What's Wrong?

This is a regression of #47237 (closed and locked, so filing a new issue as instructed by the bot).

With multiple marketplaces installed, the VS Code extension's "Manage Plugins" panel shows "No plugins available. Add a marketplace to discover plugins." even though marketplaces are correctly configured. The CLI is unaffected.

#47237 was reported fixed as of 2.1.117, but the exact same failure signature is back in 2.1.169.

What Should Happen?

The "Manage Plugins" panel should list available plugins from all configured marketplaces, regardless of total marketplace metadata size.

Error Messages/Logs

From ~/Library/Application Support/Code/logs/.../exthost/Anthropic.claude-code/Claude VSCode.log:

Received message from webview: {"type":"request","requestId":"siwux8jtgk","request":{"type":"list_plugins","includeAvailable":true}}
[error] Error processing client request: SyntaxError: Unterminated string in JSON at position 65480 (line 1420 column 28)

Position 65480 ≈ 65536 bytes (64 KB) — same root cause as #47237: the list_plugins includeAvailable:true subprocess output is truncated at the OS pipe buffer limit, producing unparseable JSON. (#47237 failed at position 65496.)

Steps to Reproduce

1. Install multiple marketplaces so that the list_plugins includeAvailable:true response exceeds 64 KB. My setup (4 marketplaces):

• anthropic-agent-skills (15 MB on disk)
• claude-plugins-official (5.3 MB)
• plus two custom/company marketplaces (3.6 MB, 1.5 MB)

1. Open the "Manage Plugins" panel in the VS Code extension
2. Panel shows "No plugins available. Add a marketplace to discover plugins."
3. Extension log shows the JSON SyntaxError above

Claude Model

None

Is this a regression?

Yes

Last Working Version

2.1.117 (per the fix confirmation on #47237)

Claude Code Version

CLI 2.1.170 / VS Code extension 2.1.169

Platform

VS Code extension

Operating System

macOS (Darwin 25.3.0, arm64)

Terminal/Shell

Terminal.app (macOS)

Additional Information

Suggested fix from #47237 still applies: use a temp file or streaming output instead of a single stdout pipe read for list_plugins includeAvailable:true, so large marketplace datasets aren't truncated at the 64 KB pipe buffer limit.