From 27fdb08000396912f603a19d5ffd084e25da9630 Mon Sep 17 00:00:00 2001
From: Jonathan Davies <jpds@protonmail.com>
Date: Sun, 16 Aug 2026 20:03:53 +0000
Subject: [PATCH] feat(lsp): add Marksman language server for Markdown

---
 packages/core/src/v1/config/lsp.ts    |  1 +
 packages/opencode/src/lsp/server.ts   | 17 +++++++++++++++++
 packages/web/src/content/docs/lsp.mdx |  1 +
 3 files changed, 19 insertions(+)

diff --git a/packages/core/src/v1/config/lsp.ts b/packages/core/src/v1/config/lsp.ts
index 89a58b5b2c9b..2edee94b6d41 100644
--- a/packages/core/src/v1/config/lsp.ts
+++ b/packages/core/src/v1/config/lsp.ts
@@ -58,6 +58,7 @@ export const builtinServerIds = [
   "tinymist",
   "haskell-language-server",
   "julials",
+  "marksman",
 ]
 
 export const requiresExtensionsForCustomServers = Schema.makeFilter<
diff --git a/packages/opencode/src/lsp/server.ts b/packages/opencode/src/lsp/server.ts
index 2be68aa5a92d..a8cf83ff94ee 100644
--- a/packages/opencode/src/lsp/server.ts
+++ b/packages/opencode/src/lsp/server.ts
@@ -1981,3 +1981,20 @@ export const JuliaLS: Info = {
     }
   },
 }
+
+export const Marksman: Info = {
+  id: "marksman",
+  extensions: [".md", ".markdown"],
+  root: NearestRoot([".git", ".marksman.toml"]),
+  async spawn(root) {
+    const bin = which("marksman")
+    if (!bin) {
+      return
+    }
+    return {
+      process: spawn(bin, ["server"], {
+        cwd: root,
+      }),
+    }
+  },
+}
diff --git a/packages/web/src/content/docs/lsp.mdx b/packages/web/src/content/docs/lsp.mdx
index b9428e5b2d30..204f63af4b42 100644
--- a/packages/web/src/content/docs/lsp.mdx
+++ b/packages/web/src/content/docs/lsp.mdx
@@ -30,6 +30,7 @@ OpenCode comes with several built-in LSP servers for popular languages:
 | julials            | .jl                                                                 | `julia` and `LanguageServer.jl` installed                    |
 | kotlin-ls          | .kt, .kts                                                           | Auto-installs for Kotlin projects                            |
 | lua-ls             | .lua                                                                | Auto-installs for Lua projects                               |
+| marksman           | .md, .markdown                                                      | `marksman` command available                                 |
 | nixd               | .nix                                                                | `nixd` command available                                     |
 | ocaml-lsp          | .ml, .mli                                                           | `ocamllsp` command available                                 |
 | oxlint             | .ts, .tsx, .js, .jsx, .mjs, .cjs, .mts, .cts, .vue, .astro, .svelte | `oxlint` dependency in project                               |