Language Server Protocol (LSP)

runmat-lsp provides editor services for MATLAB/RunMat source: diagnostics, hover documentation, completion, signature help, semantic highlighting, go-to-definition, references, symbols, and formatting.

The server analyzes documents with the same lexer, parser, HIR lowering, static analysis, builtin metadata, and VM compile checks used elsewhere in RunMat. It does not run user code or create an execution session.

Editor Surface

Capability	Source of information
Error diagnostics	Syntax errors, HIR lowering errors, VM compile errors, and error-severity static-analysis diagnostics.
Warning and information diagnostics	Shape analysis, MIR analysis, and non-blocking semantic diagnostics.
Semantic highlighting	Lexer tokens plus semantic roles for functions, parameters, variables, namespaces, and builtins.
Hover	Inferred variable kinds/types, global variables, builtin docs, and builtin constants.
Completion	Globals, local variables, document functions, builtins, and constants.
Signature help	Builtin descriptors and user-defined function signatures.
Go to definition and references	Local bindings, document functions, and project functions when the project can be discovered.
Outline and workspace symbols	User-defined functions from open documents and project files.
Formatting	Conservative whitespace cleanup.

Analysis Flow

Loading diagram...

Analysis preserves partial results when a document is invalid. A syntax error can still leave token information available for highlighting and ranges, and a compile error can still point to the relevant source span without execution.

Capability Coverage

Feature	Native LSP	WASM exports	Notes
Incremental document sync	Yes	Open/change document calls	Native sync is incremental; WASM stores complete text per URI.
Diagnostics	Yes	Yes	Syntax, HIR lowering, VM compile, and semantic lint diagnostics.
Hover	Yes	Yes	Local variables, globals, builtins, and builtin constants.
Completion	Yes	Yes	Globals, function locals, document functions, builtins, and constants.
Signature help	Yes	Yes	Builtin descriptors and user-defined function signatures.
Semantic tokens	Yes	Yes	Keywords, functions, variables, parameters, namespaces, strings, numbers, operators, comments.
Go to definition	Yes	Yes	Same-document symbols plus project functions when project discovery is available.
References	Yes	Yes	Same-document references plus project functions when project discovery is available.
Document symbols	Yes	Yes	Function symbols with signature details.
Workspace symbols	Yes	Yes	Open documents and discovered project files, filtered by query on native LSP.
Formatting	Yes	Yes	Whitespace normalization only: trailing whitespace, newline normalization, and blank-line collapse.
Rename, code actions, inlay hints	No	No	These capabilities are not advertised by the server.

Runtime Scope

The LSP compiles far enough to answer editor requests, but it does not create a RunMatSession, mutate workspace state, invoke user functions, or evaluate runtime side effects. Its checks are static:

Parser compatibility follows the configured language mode (runmat, matlab, or strict).
HIR lowering resolves bindings, calls, imports, and project-visible symbols.
Static analysis contributes shape and MIR diagnostics.
VM compilation catches bytecode-level compile errors before execution.
Builtin metadata drives editor documentation instead of duplicating handwritten LSP-only references.

This keeps editor feedback aligned with runtime semantics while keeping idle analysis side-effect free.

Page Map

Page	Purpose
Diagnostics & Highlighting	Error, warning, status, and semantic-token behavior.
Editor Features	Hover, completion, signature help, navigation, symbols, formatting, and native/WASM host behavior.

For compiler internals, see Compilation Pipeline. For execution after compilation, see VM Interpreter & Bytecode. For browser embedding, see WASM & TypeScript/JavaScript.