diff --git a/packages/opencode/src/config/config.ts b/packages/opencode/src/config/config.ts
index 261731b8b0..dfdcb0343e 100644
--- a/packages/opencode/src/config/config.ts
+++ b/packages/opencode/src/config/config.ts
@@ -255,19 +255,20 @@ export namespace Config {
     const pkg = path.join(dir, "package.json")
     const targetVersion = Installation.isLocal() ? "*" : Installation.VERSION
 
-    const json = await Bun.file(pkg)
-      .json()
-      .catch(() => ({}))
+    const json = await Filesystem.readJson<{ dependencies?: Record<string, string> }>(pkg).catch(() => ({
+      dependencies: {},
+    }))
     json.dependencies = {
       ...json.dependencies,
       "@opencode-ai/plugin": targetVersion,
     }
-    await Bun.write(pkg, JSON.stringify(json, null, 2))
+    await Filesystem.writeJson(pkg, json)
     await new Promise((resolve) => setTimeout(resolve, 3000))
 
     const gitignore = path.join(dir, ".gitignore")
-    const hasGitIgnore = await Bun.file(gitignore).exists()
-    if (!hasGitIgnore) await Bun.write(gitignore, ["node_modules", "package.json", "bun.lock", ".gitignore"].join("\n"))
+    const hasGitIgnore = await Filesystem.exists(gitignore)
+    if (!hasGitIgnore)
+      await Filesystem.write(gitignore, ["node_modules", "package.json", "bun.lock", ".gitignore"].join("\n"))
 
     // Install any additional dependencies defined in the package.json
     // This allows local plugins and custom tools to use external packages
@@ -303,11 +304,10 @@ export namespace Config {
     if (!existsSync(nodeModules)) return true
 
     const pkg = path.join(dir, "package.json")
-    const pkgFile = Bun.file(pkg)
-    const pkgExists = await pkgFile.exists()
+    const pkgExists = await Filesystem.exists(pkg)
     if (!pkgExists) return true
 
-    const parsed = await pkgFile.json().catch(() => null)
+    const parsed = await Filesystem.readJson<{ dependencies?: Record<string, string> }>(pkg).catch(() => null)
     const dependencies = parsed?.dependencies ?? {}
     const depVersion = dependencies["@opencode-ai/plugin"]
     if (!depVersion) return true
@@ -1220,7 +1220,7 @@ export namespace Config {
           if (provider && model) result.model = `${provider}/${model}`
           result["$schema"] = "https://opencode.ai/config.json"
           result = mergeDeep(result, rest)
-          await Bun.write(path.join(Global.Path.config, "config.json"), JSON.stringify(result, null, 2))
+          await Filesystem.writeJson(path.join(Global.Path.config, "config.json"), result)
           await fs.unlink(legacy)
         })
         .catch(() => {})
@@ -1231,12 +1231,10 @@ export namespace Config {
 
   async function loadFile(filepath: string): Promise<Info> {
     log.info("loading", { path: filepath })
-    let text = await Bun.file(filepath)
-      .text()
-      .catch((err) => {
-        if (err.code === "ENOENT") return
-        throw new JsonError({ path: filepath }, { cause: err })
-      })
+    let text = await Filesystem.readText(filepath).catch((err: any) => {
+      if (err.code === "ENOENT") return
+      throw new JsonError({ path: filepath }, { cause: err })
+    })
     if (!text) return {}
     return load(text, filepath)
   }
@@ -1263,21 +1261,19 @@ export namespace Config {
         }
         const resolvedPath = path.isAbsolute(filePath) ? filePath : path.resolve(configDir, filePath)
         const fileContent = (
-          await Bun.file(resolvedPath)
-            .text()
-            .catch((error) => {
-              const errMsg = `bad file reference: "${match}"`
-              if (error.code === "ENOENT") {
-                throw new InvalidError(
-                  {
-                    path: configFilepath,
-                    message: errMsg + ` ${resolvedPath} does not exist`,
-                  },
-                  { cause: error },
-                )
-              }
-              throw new InvalidError({ path: configFilepath, message: errMsg }, { cause: error })
-            })
+          await Filesystem.readText(resolvedPath).catch((error: any) => {
+            const errMsg = `bad file reference: "${match}"`
+            if (error.code === "ENOENT") {
+              throw new InvalidError(
+                {
+                  path: configFilepath,
+                  message: errMsg + ` ${resolvedPath} does not exist`,
+                },
+                { cause: error },
+              )
+            }
+            throw new InvalidError({ path: configFilepath, message: errMsg }, { cause: error })
+          })
         ).trim()
         // escape newlines/quotes, strip outer quotes
         text = text.replace(match, () => JSON.stringify(fileContent).slice(1, -1))
@@ -1314,7 +1310,7 @@ export namespace Config {
         parsed.data.$schema = "https://opencode.ai/config.json"
         // Write the $schema to the original text to preserve variables like {env:VAR}
         const updated = original.replace(/^\s*\{/, '{\n  "$schema": "https://opencode.ai/config.json",')
-        await Bun.write(configFilepath, updated).catch(() => {})
+        await Filesystem.write(configFilepath, updated).catch(() => {})
       }
       const data = parsed.data
       if (data.plugin) {
@@ -1370,7 +1366,7 @@ export namespace Config {
   export async function update(config: Info) {
     const filepath = path.join(Instance.directory, "config.json")
     const existing = await loadFile(filepath)
-    await Bun.write(filepath, JSON.stringify(mergeDeep(existing, config), null, 2))
+    await Filesystem.writeJson(filepath, mergeDeep(existing, config))
     await Instance.dispose()
   }
 
@@ -1441,24 +1437,22 @@ export namespace Config {
 
   export async function updateGlobal(config: Info) {
     const filepath = globalConfigFile()
-    const before = await Bun.file(filepath)
-      .text()
-      .catch((err) => {
-        if (err.code === "ENOENT") return "{}"
-        throw new JsonError({ path: filepath }, { cause: err })
-      })
+    const before = await Filesystem.readText(filepath).catch((err: any) => {
+      if (err.code === "ENOENT") return "{}"
+      throw new JsonError({ path: filepath }, { cause: err })
+    })
 
     const next = await (async () => {
       if (!filepath.endsWith(".jsonc")) {
         const existing = parseConfig(before, filepath)
         const merged = mergeDeep(existing, config)
-        await Bun.write(filepath, JSON.stringify(merged, null, 2))
+        await Filesystem.writeJson(filepath, merged)
         return merged
       }
 
       const updated = patchJsonc(before, config)
       const merged = parseConfig(updated, filepath)
-      await Bun.write(filepath, updated)
+      await Filesystem.write(filepath, updated)
       return merged
     })()