Add support for `R formatter` in formatters (#3918)

Co-authored-by: Aiden Cline <[email protected]>

4 files changed, 49 insertions, 2 deletions

diff --git a/packages/opencode/src/bun/index.ts b/packages/opencode/src/bun/index.ts
index 5f1847275..2a8b48eff 100644
--- a/packages/opencode/src/bun/index.ts
+++ b/packages/opencode/src/bun/index.ts
@@ -8,7 +8,10 @@ import { readableStreamToText } from "bun"
 export namespace BunProc {
   const log = Log.create({ service: "bun" })
 
-  export async function run(cmd: string[], options?: Bun.SpawnOptions.OptionsObject<any, any, any>) {
+  export async function run(
+    cmd: string[],
+    options?: Bun.SpawnOptions.OptionsObject<any, any, any>,
+  ) {
     log.info("running", {
       cmd: [which(), ...cmd],
       ...options,
diff --git a/packages/opencode/src/format/formatter.ts b/packages/opencode/src/format/formatter.ts
index baa39906f..a8b8e9de5 100644
--- a/packages/opencode/src/format/formatter.ts
+++ b/packages/opencode/src/format/formatter.ts
@@ -1,3 +1,4 @@
+import { readableStreamToText } from "bun"
 import { BunProc } from "../bun"
 import { Instance } from "../project/instance"
 import { Filesystem } from "../util/filesystem"
@@ -131,7 +132,21 @@ export const zig: Info = {
 export const clang: Info = {
   name: "clang-format",
   command: ["clang-format", "-i", "$FILE"],
-  extensions: [".c", ".cc", ".cpp", ".cxx", ".c++", ".h", ".hh", ".hpp", ".hxx", ".h++", ".ino", ".C", ".H"],
+  extensions: [
+    ".c",
+    ".cc",
+    ".cpp",
+    ".cxx",
+    ".c++",
+    ".h",
+    ".hh",
+    ".hpp",
+    ".hxx",
+    ".h++",
+    ".ino",
+    ".C",
+    ".H",
+  ],
   async enabled() {
     const items = await Filesystem.findUp(".clang-format", Instance.directory, Instance.worktree)
     return items.length > 0
@@ -177,6 +192,33 @@ export const ruff: Info = {
   },
 }
 
+export const rlang: Info = {
+  name: "air",
+  command: ["air", "format", "$FILE"],
+  extensions: [".R"],
+  async enabled() {
+    const airPath = Bun.which("air")
+    if (airPath == null) return false
+
+    try {
+      const proc = Bun.spawn(["air", "--help"], {
+        stdout: "pipe",
+        stderr: "pipe",
+      })
+      await proc.exited
+      const output = await readableStreamToText(proc.stdout)
+
+      // Check for "Air: An R language server and formatter"
+      const firstLine = output.split("\n")[0]
+      const hasR = firstLine.includes("R language")
+      const hasFormatter = firstLine.includes("formatter")
+      return hasR && hasFormatter
+    } catch (error) {
+      return false
+    }
+  },
+}
+
 export const uvformat: Info = {
   name: "uv format",
   command: ["uv", "format", "--", "$FILE"],
diff --git a/packages/opencode/src/format/index.ts b/packages/opencode/src/format/index.ts
index b42940934..e307496c4 100644
--- a/packages/opencode/src/format/index.ts
+++ b/packages/opencode/src/format/index.ts
@@ -69,6 +69,7 @@ export namespace Format {
       log.info("checking", { name: item.name, ext })
       if (!item.extensions.includes(ext)) continue
       if (!(await isEnabled(item))) continue
+      log.info("enabled", { name: item.name, ext })
       result.push(item)
     }
     return result
diff --git a/packages/web/src/content/docs/formatters.mdx b/packages/web/src/content/docs/formatters.mdx
index 4b46a4f63..9fc41a53d 100644
--- a/packages/web/src/content/docs/formatters.mdx
+++ b/packages/web/src/content/docs/formatters.mdx
@@ -25,6 +25,7 @@ OpenCode comes with several built-in formatters for popular languages and framew
 | rubocop        | .rb, .rake, .gemspec, .ru                                                                                | `rubocop` command available             |
 | standardrb     | .rb, .rake, .gemspec, .ru                                                                                | `standardrb` command available          |
 | htmlbeautifier | .erb, .html.erb                                                                                          | `htmlbeautifier` command available      |
+| air            | .R                                                                                                       | `air` command available                 |
 
 So if your project has `prettier` in your `package.json`, OpenCode will automatically use it.