IFC

zed-ifc

IFC language support for Zed.

This extension adds support for Industry Foundation Classes (.ifc) files using:

• IFC-Language-Server for language features
• tree-sitter-ifc for parsing and syntax highlighting

Features

• Syntax highlighting for STEP/IFC source
• Automatic .ifc file detection
• Hover for IFC entity names and references
• Hover for IFC enumeration options
• Hover information for derived attributes
• Go to definition for local #123 references
• Find references within the current document
• Document highlighting for local #123 references
• Signature help for IFC entity parameter lists
• Schema-aware diagnostics for IFC 2x3, IFC 4, and IFC 4x3 files
• Range-based semantic tokens for syntax highlighting
• Configurable AST parsing threshold for large IFC files
• Optional local EXPRESS schema configuration for custom IFC schemas

Installation

Install the extension from the Zed extensions page.

For local development, use zed: install dev extension and select this repository.

Language Server

The extension downloads the pinned official ifc-language-server release asset from GitHub and caches it in Zed's extension working directory. Executables on PATH and custom binary.path settings are intentionally ignored.

cargo clean only removes Rust build artifacts for this extension. It does not remove a previously downloaded IFC language server from Zed's extension working directory. The extension runs the downloaded binary directly, so its stderr tracing output is visible via Zed's "View Logs" action on the language server. It sets IFC_LSP_LOG to ifc_language_server=info,tower_lsp=warn by default; set IFC_LSP_LOG in the shell environment before launching Zed to override it.

Supported auto-download targets:

• macOS arm64
• macOS x86_64
• Linux x86_64
• Windows x86_64

Pinned upstream versions in this repository:

• IFC-Language-Server v0.6.0, published August 5, 2026
• tree-sitter-ifc commit bd5039f5d7929a9a8e1c138cd449ec385f17789e, dated March 24, 2026

Configuration

Large files and semantic tokens

The extension sends these IFC language server initialization_options by default:

{
  "astFileSizeLimitMb": 70,
  "semanticTokensEnabled": true
}

Override the AST threshold for tree-sitter-backed diagnostics and derived-value hover with astFileSizeLimitMb. Files above the threshold keep basic hover, local navigation, find references, document highlighting, signature help, and range-based semantic tokens available, but skip AST-backed diagnostics and derived-value hover.

{
  "lsp": {
    "ifc-language-server": {
      "initialization_options": {
        "astFileSizeLimitMb": 128,
        "semanticTokensEnabled": true
      }
    }
  },
  "languages": {
    "IFC": {
      "semantic_tokens": "combined"
    }
  }
}

Zed does not request semantic tokens by default. Use "semantic_tokens": "combined" to overlay LSP semantic tokens on tree-sitter highlighting, or "full" to use only LSP semantic tokens. Configuration changes are only applied when the language server restarts; use editor: restart language server from the Command Palette after changing these values.

Custom EXPRESS schemas

The IFC language server reads custom schema configuration from LSP initialization_options. Open Zed's settings from the Command Palette with zed: open settings or zed: open project settings, then add:

{
  "lsp": {
    "ifc-language-server": {
      "initialization_options": {
        "overwriteExpSchemaWithLocal": "/absolute/path/to/IFC4x2.exp",
        "addLocalSchemaToSelection": [
          "/absolute/path/to/IFC4x1.exp",
          "/absolute/path/to/custom-schemas"
        ]
      }
    }
  }
}

On Windows, escape backslashes in JSON strings:

{
  "lsp": {
    "ifc-language-server": {
      "initialization_options": {
        "overwriteExpSchemaWithLocal": "C:\\Users\\alice\\express\\IFC4x2.exp",
        "addLocalSchemaToSelection": [
          "C:\\Users\\alice\\express\\custom-schemas"
        ]
      }
    }
  }
}

overwriteExpSchemaWithLocal forces one .exp schema for diagnostics and hover. addLocalSchemaToSelection adds .exp files or directories containing .exp files to the schema lookup pool. Configuration changes are only applied when the language server restarts; use editor: restart language server from the Command Palette after changing these values.

Development

cargo check

Generated local extension artifacts such as extension.wasm and fetched grammar caches are intentionally ignored and are not meant to be committed.