fix: remove BUN_BE_BUN workaround, use node for ESLint server

Replace tsx dependency with explicit 'node' invocation for the
compiled ESLint server. Remove all BUN_BE_BUN env var references
which are no longer needed after the Bun-to-Node migration.

packages/opencode/src/format/formatter.ts

@@ -35,9 +35,6 @@ export const mix: Info = {
 
 export const prettier: Info = {
   name: "prettier",
-  environment: {
-    BUN_BE_BUN: "1",
-  },
   extensions: [
     ".js",
     ".jsx",
@@ -83,9 +80,6 @@ export const prettier: Info = {
 
 export const oxfmt: Info = {
   name: "oxfmt",
-  environment: {
-    BUN_BE_BUN: "1",
-  },
   extensions: [".js", ".jsx", ".mjs", ".cjs", ".ts", ".tsx", ".mts", ".cts"],
   async enabled() {
     if (!Flag.OPENCODE_EXPERIMENTAL_OXFMT) return false
@@ -105,9 +99,6 @@ export const oxfmt: Info = {
 
 export const biome: Info = {
   name: "biome",
-  environment: {
-    BUN_BE_BUN: "1",
-  },
   extensions: [
     ".js",
     ".jsx",

packages/opencode/src/lsp/server.ts

@@ -107,7 +107,6 @@ export namespace LSPServer {
         cwd: root,
         env: {
           ...process.env,
-          BUN_BE_BUN: "1",
         },
       })
       return {
@@ -137,7 +136,6 @@ export namespace LSPServer {
         cwd: root,
         env: {
           ...process.env,
-          BUN_BE_BUN: "1",
         },
       })
       return {
@@ -193,11 +191,10 @@ export namespace LSPServer {
         log.info("installed VS Code ESLint server", { serverPath })
       }
 
-      const proc = spawn(await Npm.which("tsx"), [serverPath, "--stdio"], {
+      const proc = spawn("node", [serverPath, "--stdio"], {
         cwd: root,
         env: {
           ...process.env,
-          BUN_BE_BUN: "1",
         },
       })
 
@@ -332,7 +329,6 @@ export namespace LSPServer {
         cwd: root,
         env: {
           ...process.env,
-          BUN_BE_BUN: "1",
         },
       })
 
@@ -516,7 +512,6 @@ export namespace LSPServer {
         cwd: root,
         env: {
           ...process.env,
-          BUN_BE_BUN: "1",
         },
       })
       return {
@@ -1015,7 +1010,6 @@ export namespace LSPServer {
         cwd: root,
         env: {
           ...process.env,
-          BUN_BE_BUN: "1",
         },
       })
       return {
@@ -1048,7 +1042,6 @@ export namespace LSPServer {
         cwd: root,
         env: {
           ...process.env,
-          BUN_BE_BUN: "1",
         },
       })
       return {
@@ -1298,7 +1291,6 @@ export namespace LSPServer {
         cwd: root,
         env: {
           ...process.env,
-          BUN_BE_BUN: "1",
         },
       })
       return {
@@ -1464,7 +1456,6 @@ export namespace LSPServer {
         cwd: root,
         env: {
           ...process.env,
-          BUN_BE_BUN: "1",
         },
       })
       return {
@@ -1547,7 +1538,6 @@ export namespace LSPServer {
         cwd: root,
         env: {
           ...process.env,
-          BUN_BE_BUN: "1",
         },
       })
       return {
@@ -1741,7 +1731,6 @@ export namespace LSPServer {
         cwd: root,
         env: {
           ...process.env,
-          BUN_BE_BUN: "1",
         },
       })
       return {

packages/opencode/src/mcp/index.ts

@@ -458,7 +458,6 @@ export namespace MCP {
         cwd,
         env: {
           ...process.env,
-          ...(cmd === "opencode" ? { BUN_BE_BUN: "1" } : {}),
           ...mcp.environment,
         },
       })