The Error

Claude Code conflicts with rust-analyzer: duplicate completions

The Fix

// Add to your VS Code settings.json
{
  "claude-code.completions.disabledLanguages": ["rust"]
}

# Open VS Code settings directly
code ~/.config/Code/User/settings.json

Why This Works

Both Claude Code and rust-analyzer register as completion providers for Rust files. VS Code merges their results, producing duplicates and slowing the completion popup. Disabling Claude Code completions for Rust files lets rust-analyzer handle language-specific completions while Claude Code still provides chat, edits, and tool use for Rust projects.

If That Doesn’t Work

# If duplicates persist, set completion provider priority
# Add to settings.json:
# "editor.snippetSuggestions": "bottom",
# "rust-analyzer.completion.autoimport.enable": true,
# "[rust]": { "editor.defaultFormatter": "rust-lang.rust-analyzer" }

# Alternatively, reload after the change
# Command Palette > Developer: Reload Window

Ensure you are running the latest versions of both extensions. Older versions of Claude Code (pre-1.2) lacked the disabledLanguages setting. If you use multiple Rust workspaces, apply the setting at the user level rather than the workspace level to avoid repeating the configuration in every project.

Prevention

Add to your CLAUDE.md:

Claude Code inline completions are disabled for Rust files. Use Claude Code for chat-based assistance and refactoring in Rust projects, not inline completions.