feat(opencode): add dotnet formatter

packages/app/src/custom-elements.d.ts

@@ -1 +1 @@
-../../ui/src/custom-elements.d.ts
+/// <reference path="../../ui/src/custom-elements.d.ts" />

packages/enterprise/src/custom-elements.d.ts

@@ -1 +1 @@
-../../ui/src/custom-elements.d.ts
+/// <reference path="../../ui/src/custom-elements.d.ts" />

packages/opencode/src/config/config.ts

@@ -1084,6 +1084,7 @@ export namespace Config {
             z.object({
               disabled: z.boolean().optional(),
               command: z.array(z.string()).optional(),
+              args: z.array(z.string()).optional(),
               environment: z.record(z.string(), z.string()).optional(),
               extensions: z.array(z.string()).optional(),
             }),

packages/opencode/src/format/formatter.ts

@@ -1,3 +1,4 @@
+import path from "path"
 import { text } from "node:stream/consumers"
 import { BunProc } from "../bun"
 import { Instance } from "../project/instance"
@@ -9,11 +10,18 @@ import { Flag } from "@/flag/flag"
 export interface Info {
   name: string
   command: string[]
+  args?: string[]
   environment?: Record<string, string>
+  setup?(file: string): Promise<Setup | undefined>
   extensions: string[]
   enabled(): Promise<boolean>
 }
 
+export interface Setup {
+  directory?: string
+  placeholders?: Record<string, string>
+}
+
 export const gofmt: Info = {
   name: "gofmt",
   command: ["gofmt", "-w", "$FILE"],
@@ -350,6 +358,41 @@ export const rustfmt: Info = {
   },
 }
 
+export const dotnetformat: Info = {
+  name: "dotnet-format",
+  command: ["dotnet", "format", "$TARGET", "--include", "$RELATIVE_FILE"],
+  async setup(file) {
+    let current = path.dirname(file)
+
+    while (true) {
+      for (const pattern of ["*.slnx", "*.sln", "*.csproj", "*.fsproj", "*.vbproj"]) {
+        const glob = new Bun.Glob(pattern)
+        const matches = Array.from(glob.scanSync({ cwd: current, absolute: true })).sort()
+        if (matches[0]) {
+          const root = path.dirname(matches[0])
+          const rel = path.relative(root, file)
+          if (!rel || rel.startsWith("..")) return
+          return {
+            directory: root,
+            placeholders: {
+              $TARGET: path.basename(matches[0]),
+              $RELATIVE_FILE: rel.split(path.sep).join("/"),
+            },
+          }
+        }
+      }
+
+      const parent = path.dirname(current)
+      if (parent === current) break
+      current = parent
+    }
+  },
+  extensions: [".cs", ".vb", ".fs", ".fsi", ".fsx", ".fsscript"],
+  async enabled() {
+    return which("dotnet") !== null
+  },
+}
+
 export const pint: Info = {
   name: "pint",
   command: ["./vendor/bin/pint", "$FILE"],

packages/opencode/src/format/index.ts

@@ -45,16 +45,18 @@ export namespace Format {
         delete formatters[name]
         continue
       }
-      const result: Formatter.Info = mergeDeep(formatters[name] ?? {}, {
-        command: [],
-        extensions: [],
-        ...item,
-      })
+      const base = formatters[name]
+      const merged = mergeDeep(base ?? { command: [], extensions: [] }, item)
+      const result: Formatter.Info = {
+        ...merged,
+        name,
+        command: merged.command ?? [],
+        extensions: merged.extensions ?? [],
+        enabled: base?.enabled ?? (async () => true),
+      }
 
       if (result.command.length === 0) continue
 
-      result.enabled = async () => true
-      result.name = name
       formatters[name] = result
     }
 
@@ -109,12 +111,32 @@ export namespace Format {
       const ext = path.extname(file)
 
       for (const item of await getFormatter(ext)) {
-        log.info("running", { command: item.command })
+        let command = item.command
         try {
+          const cfg = await item.setup?.(file)
+          const placeholders: Record<string, string> = {
+            $FILE: file,
+            ...(cfg?.placeholders ?? {}),
+          }
+          const cwd = cfg?.directory ?? path.dirname(file)
+          command = item.command.map((part) => {
+            let result = part
+            for (const [key, value] of Object.entries(placeholders).toSorted((a, b) => b[0].length - a[0].length)) {
+              result = result.replaceAll(key, value)
+            }
+            return result
+          })
+          if (command.some((part) => /\$[A-Z][A-Z0-9_]*/.test(part))) {
+            continue
+          }
+          command.push(...(item.args ?? []))
+
+          log.info("running", { command: command })
+
           const proc = Process.spawn(
-            item.command.map((x) => x.replace("$FILE", file)),
+            command,
             {
-              cwd: Instance.directory,
+              cwd,
               env: { ...process.env, ...item.environment },
               stdout: "ignore",
               stderr: "ignore",
@@ -123,13 +145,15 @@ export namespace Format {
           const exit = await proc.exited
           if (exit !== 0)
             log.error("failed", {
-              command: item.command,
+              command,
+              cwd,
+              exit,
               ...item.environment,
             })
         } catch (error) {
           log.error("failed to format file", {
             error,
-            command: item.command,
+            command,
             ...item.environment,
             file,
           })

packages/opencode/src/util/which.ts

@@ -1,10 +1,12 @@
 import whichPkg from "which"
 
 export function which(cmd: string, env?: NodeJS.ProcessEnv) {
+  const path = env?.PATH ?? env?.Path ?? process.env.PATH ?? process.env.Path
+  const pathExt = env?.PATHEXT ?? env?.PathExt ?? process.env.PATHEXT ?? process.env.PathExt
   const result = whichPkg.sync(cmd, {
     nothrow: true,
-    path: env?.PATH ?? env?.Path ?? process.env.PATH ?? process.env.Path,
-    pathExt: env?.PATHEXT ?? env?.PathExt ?? process.env.PATHEXT ?? process.env.PathExt,
+    path,
+    pathExt
   })
   return typeof result === "string" ? result : null
 }

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

@@ -446,6 +446,9 @@ You can configure code formatters through the `formatter` option.
 {
   "$schema": "https://opencode.ai/config.json",
   "formatter": {
+    "dotnet-format": {
+      "args": ["--severity", "info"]
+    },
     "prettier": {
       "disabled": true
     },

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

@@ -20,6 +20,7 @@ OpenCode comes with several built-in formatters for popular languages and framew
 | cljfmt               | .clj, .cljs, .cljc, .edn                                                                                 | `cljfmt` command available                                                                            |
 | dart                 | .dart                                                                                                    | `dart` command available                                                                              |
 | dfmt                 | .d                                                                                                       | `dfmt` command available                                                                              |
+| dotnet-format        | .cs, .vb, .fs, .fsi, .fsx, .fsscript                                                                     | `dotnet` command available and a nearest `.slnx`, `.sln`, `.csproj`, `.fsproj`, or `.vbproj`        |
 | gleam                | .gleam                                                                                                   | `gleam` command available                                                                             |
 | gofmt                | .go                                                                                                      | `gofmt` command available                                                                             |
 | htmlbeautifier       | .erb, .html.erb                                                                                          | `htmlbeautifier` command available                                                                    |
@@ -71,6 +72,7 @@ Each formatter configuration supports the following:
 
 | Property      | Type     | Description                                             |
 | ------------- | -------- | ------------------------------------------------------- |
+| `args`        | string[] | Additional arguments appended to the formatter command  |
 | `disabled`    | boolean  | Set this to `true` to disable the formatter             |
 | `command`     | string[] | The command to run for formatting                       |
 | `environment` | object   | Environment variables to set when running the formatter |
@@ -130,3 +132,5 @@ You can override the built-in formatters or add new ones by specifying the comma
 ```
 
 The **`$FILE` placeholder** in the command will be replaced with the path to the file being formatted.
+
+The `args` property is appended after the formatter command. Use it when you want to tweak a built-in formatter without replacing its full command. If you need complete control over argument order, override `command` instead.