feat: add ReScript LSP support

packages/opencode/src/lsp/language.ts

@@ -115,6 +115,8 @@ export const LANGUAGE_EXTENSIONS: Record<string, string> = {
   ".tfvars": "terraform-vars",
   ".hcl": "hcl",
   ".nix": "nix",
+  ".res": "rescript",
+  ".resi": "rescript",
   ".typ": "typst",
   ".typc": "typst",
 } as const

packages/opencode/src/lsp/server.ts

@@ -1930,6 +1930,45 @@ export namespace LSPServer {
     },
   }
 
+  export const ReScript: Info = {
+    id: "rescript",
+    extensions: [".res", ".resi"],
+    root: NearestRoot(["rescript.json", "bsconfig.json"]),
+    async spawn(root) {
+      let binary = which("rescript-language-server")
+      const args: string[] = []
+      if (!binary) {
+        const js = path.join(Global.Path.bin, "node_modules", "@rescript", "language-server", "out", "cli.js")
+        if (!(await Filesystem.exists(js))) {
+          if (Flag.OPENCODE_DISABLE_LSP_DOWNLOAD) return
+          await Process.spawn([BunProc.which(), "install", "@rescript/language-server"], {
+            cwd: Global.Path.bin,
+            env: {
+              ...process.env,
+              BUN_BE_BUN: "1",
+            },
+            stdout: "pipe",
+            stderr: "pipe",
+            stdin: "pipe",
+          }).exited
+        }
+        binary = BunProc.which()
+        args.push("run", js)
+      }
+      args.push("--stdio")
+      const proc = spawn(binary, args, {
+        cwd: root,
+        env: {
+          ...process.env,
+          BUN_BE_BUN: "1",
+        },
+      })
+      return {
+        process: proc,
+      }
+    },
+  }
+
   export const Nixd: Info = {
     id: "nixd",
     extensions: [".nix"],

packages/web/src/content/docs/lsp.mdx

@@ -35,6 +35,7 @@ OpenCode comes with several built-in LSP servers for popular languages:
 | oxlint             | .ts, .tsx, .js, .jsx, .mjs, .cjs, .mts, .cts, .vue, .astro, .svelte | `oxlint` dependency in project                               |
 | php intelephense   | .php                                                                | Auto-installs for PHP projects                               |
 | prisma             | .prisma                                                             | `prisma` command available                                   |
+| rescript           | .res, .resi                                                         | Auto-installs @rescript/language-server                      |
 | pyright            | .py, .pyi                                                           | `pyright` dependency installed                               |
 | ruby-lsp (rubocop) | .rb, .rake, .gemspec, .ru                                           | `ruby` and `gem` commands available                          |
 | rust               | .rs                                                                 | `rust-analyzer` command available                            |