RQL in VS Code

The Bifrost VS Code extension recognizes .rql files as Bifrost RQL. RQL, the Rune Query Language, is Bifrost’s experimental S-expression frontend for structural query_code searches.

With the Bifrost language server running and indexed, use the Play button in an RQL editor title to execute the current document. Unsaved edits are sent to the active LSP session, so you can refine a query without first saving it.

For (explain QUERY) and (profile QUERY), the extension shows the report in the Bifrost output channel. Profile output includes the complete versioned JSON telemetry, while its nested ordinary results remain available in the grouped query-results tree. Explain mode is planning-only and therefore does not show a misleading “no results” notification. See Explain and Profile CodeQuery.

Use VS Code’s Format Document command to format .rql and saved .rune files through the Bifrost language server. Bracketed forms remain on one line through 120 columns. Longer forms place their entries on indented lines and keep :property value pairs together when possible. The formatter preserves comments and does not edit incomplete S-expressions.

RQL Policy Documents

The extension recognizes .rqlp as the distinct Bifrost RQL Policy language. Policy and endpoint buffers receive debounced source validation, schema-resolution hover, optional-version completion, conservative policy highlighting, and 100-column formatting. Nested query syntax receives RQL highlighting only inside (rql ...); an (rql-file ...) reference is validated and resolved later by a workspace-backed policy load.

Policy validation uses the current unsaved source, but it deliberately does not load endpoint directories, catalogs, or referenced query files. Formatting preserves comments and omitted :schema-version fields and returns no edit for an incomplete S-expression.

An .rqlp buffer is not an RQL query document. It never enables the Play action, cannot publish findings into Bifrost Query Results, and cannot be passed to --query-file. Execute a saved (policy ...) root with bifrost --policy-file; an (endpoint ...) is a diagnostic-neutral dependency, not an executable root. See Static-Analysis Policies for the complete authoring and reporting contract.

This Play action is a VS Code language-server feature. It does not start an MCP server, expose query_code to an agent, or prove that an agent can run RQL. For agent access, configure a query-capable MCP toolset and use a saved workspace .rql file through query_file; MCP does not accept unsaved editor text or raw inline RQL. See MCP query and RQL availability.

(result-detail full
  (where "src/lsp/server.rs"
    (function :name "handle_run_rql_query_request")))

The Bifrost Query Results Explorer view groups tagged structural-match, declaration, and file results by path. Select a structural match or declaration to open its file and highlight the source range; selecting a file result opens the file at its first line. Pipeline wrappers such as enclosing-decl and file-of therefore remain navigable from the same view.

Query Scope

The query runs across every root indexed by the active Bifrost LSP session:

• all VS Code workspace folders by default; or
• the directories selected with bifrost.roots.

The .rql file itself may live outside the workspace. Only the code searched by the query is limited to the active indexed roots.

The Play action does not start Bifrost or wait for indexing. Start or restart the language server first, then run the query once it is ready. Use bifrost.serverPath to point the extension at a local Bifrost build during extension development.

For the RQL syntax and REPL workflow, see Rune Query Language.