Function agent_doc_sync_try_lock 

#[unsafe(no_mangle)]
pub extern "C" fn agent_doc_sync_try_lock() -> bool

Try to acquire the sync lock. Returns true if acquired, false if already held.

Editors call this before triggering agent-doc sync. If it returns false, skip the sync (another sync is in progress). Call agent_doc_sync_unlock() when the sync completes.

This is a cross-editor shared lock — prevents concurrent syncs from IntelliJ and VS Code plugins simultaneously.