Syntax highlighting, code completions and hover help for new Firestore security rules and index definitions. Name files with the extension .rule or .rules to activate. The priority for additional rules language features in roughly the order I'll get to them, if ever, is …

• Syntax Highlighting
• Code Completions
• Hover Definitions
• Snippets
• Signature Helpers
• Incremental Formatting
• Rule validation (moonshot)

See the repository milestones for issues I expect to resolve in coming releases.