From 5e9fb3cc9045f9ef9a5c33ff6c295cf0438da39b Mon Sep 17 00:00:00 2001
From: Mathews Bryan <37884221+jmbryan4@users.noreply.github.com>
Date: Tue, 21 Apr 2026 17:03:09 -0500
Subject: [PATCH] feat: replace csharp-ls with roslyn-language-server (#14463)

Co-authored-by: Mathews <Mathews.Bryan@cincpro.com>
---
 packages/opencode/src/lsp/server.ts | 34 +++++++++++++++++++----------
 1 file changed, 22 insertions(+), 12 deletions(-)

diff --git a/packages/opencode/src/lsp/server.ts b/packages/opencode/src/lsp/server.ts
index 9182368063..a07e336864 100644
--- a/packages/opencode/src/lsp/server.ts
+++ b/packages/opencode/src/lsp/server.ts
@@ -705,32 +705,42 @@ export const CSharp: Info = {
   root: NearestRoot([".slnx", ".sln", ".csproj", "global.json"]),
   extensions: [".cs"],
   async spawn(root) {
-    let bin = which("csharp-ls")
+    let bin = which("roslyn-language-server")
     if (!bin) {
       if (!which("dotnet")) {
-        log.error(".NET SDK is required to install csharp-ls")
+        log.error(".NET SDK is required to install roslyn-language-server")
         return
       }
 
       if (Flag.OPENCODE_DISABLE_LSP_DOWNLOAD) return
-      log.info("installing csharp-ls via dotnet tool")
-      const proc = Process.spawn(["dotnet", "tool", "install", "csharp-ls", "--tool-path", Global.Path.bin], {
-        stdout: "pipe",
-        stderr: "pipe",
-        stdin: "pipe",
-      })
+      log.info("installing roslyn-language-server via dotnet tool")
+      const proc = Process.spawn(
+        [
+          "dotnet",
+          "tool",
+          "install",
+          "--global",
+          "roslyn-language-server",
+          "--prerelease",
+        ],
+        {
+          stdout: "pipe",
+          stderr: "pipe",
+          stdin: "pipe",
+        },
+      )
       const exit = await proc.exited
       if (exit !== 0) {
-        log.error("Failed to install csharp-ls")
+        log.error("Failed to install roslyn-language-server")
         return
       }
 
-      bin = path.join(Global.Path.bin, "csharp-ls" + (process.platform === "win32" ? ".exe" : ""))
-      log.info(`installed csharp-ls`, { bin })
+      bin = path.join(Global.Path.bin, "roslyn-language-server" + (process.platform === "win32" ? ".exe" : ""))
+      log.info(`installed roslyn-language-server`, { bin })
     }
 
     return {
-      process: spawn(bin, {
+      process: spawn(bin, ["--stdio", "--autoLoadProjects"], {
         cwd: root,
       }),
     }