fix(mcp): resolve local mcp runtimes

Resolve built-in local MCP runtime executables before handing command arrays to OpenCode so lsp and ast_grep do not depend on a bare node or bun lookup in the host PATH.

Keep source, dist, bootstrap, workspace-safety, and disabled_mcps behavior covered by focused tests and real OpenCode MCP status QA.

Plan: plans/fix-built-in-mcp-runtime-executables.md

src/mcp/ast-grep.test.ts

@@ -4,6 +4,7 @@ import { tmpdir } from "node:os"
 import { join } from "node:path"
 import { pathToFileURL } from "node:url"
 import { createAstGrepMcpConfig } from "./ast-grep"
+import type { RuntimeExecutable } from "./runtime-executable"
 
 const temporaryDirectories: string[] = []
 
@@ -26,6 +27,7 @@ describe("createAstGrepMcpConfig", () => {
     const unrelatedCwd = createTemporaryDirectory("omo-ast-grep-unrelated-cwd-")
     const moduleFilePath = join(packageRoot, "dist", "index.js")
     const cliPath = join(packageRoot, "packages", "ast-grep-mcp", "dist", "cli.js")
+    const nodePath = join(packageRoot, "bin", "node")
     mkdirSync(join(packageRoot, "dist"), { recursive: true })
     mkdirSync(join(packageRoot, "packages", "ast-grep-mcp", "dist"), { recursive: true })
     writeFileSync(cliPath, "#!/usr/bin/env node\n", "utf-8")
@@ -34,10 +36,12 @@ describe("createAstGrepMcpConfig", () => {
     const config = createAstGrepMcpConfig({
       cwd: unrelatedCwd,
       moduleUrl: pathToFileURL(moduleFilePath).href,
+      resolveExecutable: createResolver({ node: nodePath }),
     })
 
     // then
-    expect(config.command).toEqual(["node", cliPath, "mcp"])
+    expect(config.enabled).toBe(true)
+    expect(config.command).toEqual([nodePath, cliPath, "mcp"])
     expect(config.environment?.OMO_AST_GREP_WORKSPACE).toBe(unrelatedCwd)
   })
 
@@ -46,6 +50,7 @@ describe("createAstGrepMcpConfig", () => {
     const packageRoot = createTemporaryDirectory("omo-ast-grep-source-root-")
     const moduleFilePath = join(packageRoot, "src", "mcp", "ast-grep.ts")
     const sourceCliPath = join(packageRoot, "packages", "ast-grep-mcp", "src", "cli.ts")
+    const bunPath = join(packageRoot, "bin", "bun")
     mkdirSync(join(packageRoot, "src", "mcp"), { recursive: true })
     mkdirSync(join(packageRoot, "packages", "ast-grep-mcp", "src"), { recursive: true })
     writeFileSync(sourceCliPath, "console.log('mcp')\n", "utf-8")
@@ -54,31 +59,55 @@ describe("createAstGrepMcpConfig", () => {
     const config = createAstGrepMcpConfig({
       cwd: createTemporaryDirectory("omo-ast-grep-source-cwd-"),
       moduleUrl: pathToFileURL(moduleFilePath).href,
+      resolveExecutable: createResolver({ bun: bunPath }),
     })
 
     // then
-    expect(config.command).toEqual(["bun", sourceCliPath, "mcp"])
+    expect(config.enabled).toBe(true)
+    expect(config.command).toEqual([bunPath, sourceCliPath, "mcp"])
   })
 
   it("still returns a built-in MCP config when the cli has not been built yet", () => {
     // given
     const packageRoot = createTemporaryDirectory("omo-ast-grep-missing-root-")
     const moduleFilePath = join(packageRoot, "dist", "index.js")
+    const nodePath = join(packageRoot, "bin", "node")
     mkdirSync(join(packageRoot, "dist"), { recursive: true })
 
     // when
     const config = createAstGrepMcpConfig({
       cwd: createTemporaryDirectory("omo-ast-grep-missing-cwd-"),
       moduleUrl: pathToFileURL(moduleFilePath).href,
+      resolveExecutable: createResolver({ node: nodePath }),
     })
 
     // then
     expect(config.enabled).toBe(true)
-    expect(config.command[0]).toBe("node")
+    expect(config.command[0]).toBe(nodePath)
     expect(config.command[1]).toContain(join("packages", "ast-grep-mcp", "dist", "cli.js"))
     expect(config.command[2]).toBe("mcp")
   })
 
+  it("disables the MCP config when no runtime can launch ast-grep", () => {
+    // given
+    const packageRoot = createTemporaryDirectory("omo-ast-grep-no-runtime-root-")
+    const moduleFilePath = join(packageRoot, "dist", "index.js")
+    const cliPath = join(packageRoot, "packages", "ast-grep-mcp", "dist", "cli.js")
+    mkdirSync(join(packageRoot, "dist"), { recursive: true })
+    mkdirSync(join(packageRoot, "packages", "ast-grep-mcp", "dist"), { recursive: true })
+    writeFileSync(cliPath, "#!/usr/bin/env node\n", "utf-8")
+
+    // when
+    const config = createAstGrepMcpConfig({
+      cwd: createTemporaryDirectory("omo-ast-grep-no-runtime-cwd-"),
+      moduleUrl: pathToFileURL(moduleFilePath).href,
+      resolveExecutable: createResolver({}),
+    })
+
+    // then
+    expect(config.enabled).toBe(false)
+  })
+
   it("does not resolve the MCP command from the opened workspace", () => {
     // given
     const packageRoot = createTemporaryDirectory("omo-ast-grep-safe-package-root-")
@@ -93,6 +122,7 @@ describe("createAstGrepMcpConfig", () => {
     const config = createAstGrepMcpConfig({
       cwd: workspaceRoot,
       moduleUrl: pathToFileURL(moduleFilePath).href,
+      resolveExecutable: createResolver({ node: join(packageRoot, "bin", "node") }),
     })
 
     // then
@@ -111,9 +141,17 @@ describe("createAstGrepMcpConfig", () => {
       cwd: createTemporaryDirectory("omo-ast-grep-disabled-cwd-"),
       disabledTools: ["ast_grep_replace", "glob"],
       moduleUrl: pathToFileURL(moduleFilePath).href,
+      resolveExecutable: createResolver({ node: join(packageRoot, "bin", "node") }),
     })
 
     // then
     expect(config.environment?.OMO_AST_GREP_DISABLED_TOOLS).toBe("replace")
   })
 })
+
+function createResolver(commands: Readonly<Record<string, string>>) {
+  return (commandName: string): RuntimeExecutable => {
+    const command = commands[commandName]
+    return command ? { command, available: true } : { command: commandName, available: false }
+  }
+}