SDK docs explain CLAUDE_CODE_SYNC_PLUGIN_INSTALL and managed plugin errors

What

The Agent SDK lets programs run Claude Code without the interactive screen. Its schema descriptions, the built-in documentation for the messages it sends, were updated around plugin installation.

• Install progress: without the environment variable CLAUDE_CODE_SYNC_PLUGIN_INSTALL, plugins install in the background. In that case the install progress messages reach only the Claude desktop app, over a local standard-output connection.
• plugin_errors: now also reports plugins enabled by managed settings (organization-controlled settings) that failed to load. Over connections that may store messages, these entries carry one fixed sentence with no file path.
• CI warning: a check on plugin_errors in automated testing (CI) can trip on a throwaway machine that has no copy of the plugin, and CLAUDE_CODE_SYNC_PLUGIN_INSTALL=1 makes the first turn wait for the install.

Why

If you run Claude Code in automation, background installs can make plugin errors appear that are not real failures. Setting CLAUDE_CODE_SYNC_PLUGIN_INSTALL=1 makes the first turn wait so plugins are in place before work starts.