OpenCode

OpenCode can use Bifrost in two ways:

• OpenCode’s LSP client can start the Bifrost language server, bifrost-lsp, for definitions, references, and other editor features.
• OpenCode’s MCP client can start bifrost --mcp for Bifrost’s analyzer tools, such as get_summaries and query_code.

bifrost-lsp is not released yet

Bifrost built after release 0.12.0 does not serve LSP: bifrost --lsp exits with an error. The language server is now the separate bifrost-lsp program, and bifrost-lsp has no release yet. The lsp configuration below is ready for its first release. The mcp configuration works now. See LSP Server.

For OpenCode’s underlying host conventions, see the official LSP server, tools, MCP server documentation.

Configure LSP and MCP

Install the Bifrost CLI for MCP. See Install. The lsp entry needs a bifrost-lsp binary instead.

Add a project-local opencode.json at the root of the repository you want Bifrost to analyze. Use absolute paths for both executables and for the project root:

{
  "$schema": "https://opencode.ai/config.json",
  "lsp": {
    "bifrost": {
      "command": [
        "/absolute/path/to/bifrost-lsp",
        "--root",
        "/absolute/path/to/project"
      ],
      "extensions": [
        ".java",
        ".go",
        ".c",
        ".cc",
        ".cpp",
        ".cxx",
        ".h",
        ".hin",
        ".hpp",
        ".hh",
        ".hxx",
        ".js",
        ".mjs",
        ".cjs",
        ".jsx",
        ".ts",
        ".tsx",
        ".py",
        ".rs",
        ".php",
        ".scala",
        ".cs",
        ".rb",
        ".kt",
        ".kts"
      ]
    }
  },
  "permission": {
    "lsp": "allow"
  },
  "mcp": {
    "bifrost": {
      "type": "local",
      "command": [
        "/absolute/path/to/bifrost",
        "--root",
        "/absolute/path/to/project",
        "--mcp",
        "symbol|extended"
      ],
      "enabled": true,
      "timeout": 300000
    }
  }
}

On Windows, use forward slashes in these JSON paths or escape each backslash.

The extensions above are the source files that Bifrost analyzes. Languages is the source of this list. Bifrost does not analyze .vue, .svelte, .razor, or .cshtml files, so do not add them.

--root is the fallback workspace root. OpenCode also sends the workspace root when it initializes the server. Absolute paths stop Bifrost from binding to whatever directory OpenCode was started from.

Expose LSP to the agent

OpenCode’s agent-facing lsp tool is experimental in the tested OpenCode 1.18.3 release. Set the feature flag in the environment that starts OpenCode:

macOS and Linux:

OPENCODE_EXPERIMENTAL_LSP_TOOL=true opencode /absolute/path/to/project

PowerShell:

$env:OPENCODE_EXPERIMENTAL_LSP_TOOL = "true"
opencode C:/absolute/path/to/project

The permission.lsp setting above lets the agent call the tool. The tool supports definitions, references, hover, document and workspace symbols, implementations, and incoming and outgoing call hierarchy. Its line and character inputs are one-based even though returned LSP ranges are zero-based.

The LSP results on this page were checked with OpenCode 1.18.3 and the language server that Bifrost 0.8.19 included. They have not been checked against bifrost-lsp. Record both versions when you validate an installation:

opencode --version
/absolute/path/to/bifrost-lsp --version

OpenCode V2 currently accepts the lsp configuration shape but does not have an active LSP runtime; do not treat a successfully parsed V2 configuration as a working integration.

Validate native LSP

OpenCode starts a configured language server lazily when it opens a file whose extension matches. Run a file-specific debug command or ask the agent to make an LSP call on a real source file before interpreting an empty workspace-symbol result or checking for a server process.

The debug commands provide a model-independent smoke test:

opencode debug config
opencode debug lsp document-symbols file:///absolute/path/to/project/src/main.rs
opencode debug lsp diagnostics /absolute/path/to/project/src/main.rs

Then start OpenCode with the experimental flag and ask the agent to use only the lsp tool on a declaration unique to that checkout:

Use only the lsp tool. Call documentSymbol on src/main.rs, then call
goToDefinition and findReferences on unique_probe_symbol. Report the returned
file paths and ranges. Do not use file reading, text search, shell, or MCP.

A valid pass shows real documentSymbol, goToDefinition, and findReferences tool events and returns paths under the configured project. With Bifrost 0.8.19, OpenCode 1.18.3 also returned hover, workspace symbols, implementation lookup, and incoming and outgoing call hierarchy. To check diagnostics and edit synchronization, have OpenCode add a syntax error to a temporary source file. A working integration reports an LSP error right after the edit. With Bifrost 0.8.19, opencode debug lsp diagnostics named the source bifrost-tree-sitter. A clean file with no diagnostics does not show which server answered. Remove the probe after retaining the evidence.

Coexist with built-in servers

The object form of OpenCode’s lsp configuration keeps matching built-in servers enabled. This can be useful: a compiler-backed server can provide build-aware diagnostics while Bifrost provides build-independent repository navigation. Keep both unless overlap causes duplicate or ambiguous results or unacceptable startup latency.

To prove that Bifrost handled a smoke test, or to avoid a concrete conflict, disable only the matching built-in server. For example:

{
  "lsp": {
    "rust": {
      "disabled": true
    },
    "bifrost": {
      "command": [
        "/absolute/path/to/bifrost-lsp",
        "--root",
        "/absolute/path/to/project"
      ],
      "extensions": [".rs"]
    }
  }
}

Do not disable all built-in servers globally just to add Bifrost.

Troubleshoot LSP

• If no server starts, run a file-specific LSP debug command or ask the agent to make an LSP call on a configured source file first.
• If the agent has no lsp tool, restart OpenCode from an environment with OPENCODE_EXPERIMENTAL_LSP_TOOL=true.
• If the tool is denied, allow the lsp permission in the applicable config.
• If results come from the wrong checkout, replace relative command and root values with absolute paths and repeat the unique-declaration smoke.
• If the server exits at once with the LSP server has moved out of this repository, the command names the bifrost CLI. Point it at bifrost-lsp.
• If the wrong server version is running, set the command to the intended absolute binary instead of relying on PATH.
• If two servers produce overlap or slow startup, disable only the exact built-in server key for the affected language.
• Restart OpenCode after changing its configuration or launch environment.

The LSP tool does not give the agent get_summaries, query_code, policies, or other Bifrost tools. Use the MCP setup below for those.

Configure MCP

The opencode.json above has a project-local mcp.bifrost entry next to lsp.bifrost. The MCP entry starts the bifrost CLI, not bifrost-lsp. You can keep the MCP entry alone if you do not need the language server. If you already have an OpenCode configuration, merge those members into the existing object instead of replacing the file or its other servers.

Use absolute paths for both the Bifrost binary and project root. OpenCode’s default MCP discovery timeout is five seconds; the longer timeout above allows Bifrost to initialize and index a larger workspace on its first connection.

Quit and restart OpenCode after adding or changing MCP configuration. Then verify the server connection from the project root:

opencode mcp list

The output should list bifrost as connected.

Validate the Setup

Start OpenCode from the configured project root and use a prompt that requires an actual Bifrost MCP result:

Call the Bifrost get_summaries MCP tool on src/main.rs and report only the declared symbol names returned by that tool.

Replace src/main.rs with a source file that exists in the target repository. A successful smoke shows a bifrost_get_summaries tool call before the answer. Avoid prompts that only ask about README.md or documentation files; those can pass through ordinary file reading without proving that the analyzer-backed MCP server ran.

Apply the shared host-integration evidence contract: retain the Bifrost tool event and structured result for a known workspace declaration, verify its project-relative source path, and reject file-reading fallbacks.

Can My Agent Run RQL?

The configuration above uses symbol|extended, so a fresh OpenCode session should advertise Bifrost’s query_code tool. Ask OpenCode to call it with the inline canonical JSON fields:

{"match":{"kind":"declaration"},"limit":1}

To validate saved RQL, add a workspace file named bifrost-smoke.rql:

(limit 1 (declaration))

Then ask OpenCode to call Bifrost query_code with exactly:

{"query_file":"bifrost-smoke.rql"}

The inline call is canonical JSON. MCP accepts RQL only from a workspace .rql file through query_file. See MCP query and RQL availability for the full surface matrix and Agent Result Safety before making completeness claims.