Remove use of Bun.file (#14215)

.opencode/skill/bun-file-io/SKILL.md

@@ -1,42 +0,0 @@
----
-name: bun-file-io
-description: Use this when you are working on file operations like reading, writing, scanning, or deleting files. It summarizes the preferred file APIs and patterns used in this repo. It also notes when to use filesystem helpers for directories.
----
-
-## Use this when
-
-- Editing file I/O or scans in `packages/opencode`
-- Handling directory operations or external tools
-
-## Bun file APIs (from Bun docs)
-
-- `Bun.file(path)` is lazy; call `text`, `json`, `stream`, `arrayBuffer`, `bytes`, `exists` to read.
-- Metadata: `file.size`, `file.type`, `file.name`.
-- `Bun.write(dest, input)` writes strings, buffers, Blobs, Responses, or files.
-- `Bun.file(...).delete()` deletes a file.
-- `file.writer()` returns a FileSink for incremental writes.
-- `Bun.Glob` + `Array.fromAsync(glob.scan({ cwd, absolute, onlyFiles, dot }))` for scans.
-- Use `Bun.which` to find a binary, then `Bun.spawn` to run it.
-- `Bun.readableStreamToText/Bytes/JSON` for stream output.
-
-## When to use node:fs
-
-- Use `node:fs/promises` for directories (`mkdir`, `readdir`, recursive operations).
-
-## Repo patterns
-
-- Prefer Bun APIs over Node `fs` for file access.
-- Check `Bun.file(...).exists()` before reading.
-- For binary/large files use `arrayBuffer()` and MIME checks via `file.type`.
-- Use `Bun.Glob` + `Array.fromAsync` for scans.
-- Decode tool stderr with `Bun.readableStreamToText`.
-- For large writes, use `Bun.write(Bun.file(path), text)`.
-
-NOTE: Bun.file(...).exists() will return `false` if the value is a directory.
-Use Filesystem.exists(...) instead if path can be file or directory
-
-## Quick checklist
-
-- Use Bun APIs first.
-- Use `path.join`/`path.resolve` for paths.
-- Prefer promise `.catch(...)` over `try/catch` when possible.

packages/opencode/src/cli/cmd/tui/component/prompt/frecency.tsx

@@ -1,9 +1,10 @@
 import path from "path"
 import { Global } from "@/global"
+import { Filesystem } from "@/util/filesystem"
 import { onMount } from "solid-js"
 import { createStore } from "solid-js/store"
 import { createSimpleContext } from "../../context/helper"
-import { appendFile } from "fs/promises"
+import { appendFile, writeFile } from "fs/promises"
 
 function calculateFrecency(entry?: { frequency: number; lastOpen: number }): number {
   if (!entry) return 0
@@ -17,9 +18,9 @@ const MAX_FRECENCY_ENTRIES = 1000
 export const { use: useFrecency, provider: FrecencyProvider } = createSimpleContext({
   name: "Frecency",
   init: () => {
-    const frecencyFile = Bun.file(path.join(Global.Path.state, "frecency.jsonl"))
+    const frecencyPath = path.join(Global.Path.state, "frecency.jsonl")
     onMount(async () => {
-      const text = await frecencyFile.text().catch(() => "")
+      const text = await Filesystem.readText(frecencyPath).catch(() => "")
       const lines = text
         .split("\n")
         .filter(Boolean)
@@ -53,7 +54,7 @@ export const { use: useFrecency, provider: FrecencyProvider } = createSimpleCont
 
       if (sorted.length > 0) {
         const content = sorted.map((entry) => JSON.stringify(entry)).join("\n") + "\n"
-        Bun.write(frecencyFile, content).catch(() => {})
+        writeFile(frecencyPath, content).catch(() => {})
       }
     })
 
@@ -68,7 +69,7 @@ export const { use: useFrecency, provider: FrecencyProvider } = createSimpleCont
         lastOpen: Date.now(),
       }
       setStore("data", absolutePath, newEntry)
-      appendFile(frecencyFile.name!, JSON.stringify({ path: absolutePath, ...newEntry }) + "\n").catch(() => {})
+      appendFile(frecencyPath, JSON.stringify({ path: absolutePath, ...newEntry }) + "\n").catch(() => {})
 
       if (Object.keys(store.data).length > MAX_FRECENCY_ENTRIES) {
         const sorted = Object.entries(store.data)
@@ -76,7 +77,7 @@ export const { use: useFrecency, provider: FrecencyProvider } = createSimpleCont
           .slice(0, MAX_FRECENCY_ENTRIES)
         setStore("data", Object.fromEntries(sorted))
         const content = sorted.map(([path, entry]) => JSON.stringify({ path, ...entry })).join("\n") + "\n"
-        Bun.write(frecencyFile, content).catch(() => {})
+        writeFile(frecencyPath, content).catch(() => {})
       }
     }
 

packages/opencode/src/cli/cmd/tui/component/prompt/history.tsx

@@ -1,5 +1,6 @@
 import path from "path"
 import { Global } from "@/global"
+import { Filesystem } from "@/util/filesystem"
 import { onMount } from "solid-js"
 import { createStore, produce } from "solid-js/store"
 import { clone } from "remeda"
@@ -30,9 +31,9 @@ const MAX_HISTORY_ENTRIES = 50
 export const { use: usePromptHistory, provider: PromptHistoryProvider } = createSimpleContext({
   name: "PromptHistory",
   init: () => {
-    const historyFile = Bun.file(path.join(Global.Path.state, "prompt-history.jsonl"))
+    const historyPath = path.join(Global.Path.state, "prompt-history.jsonl")
     onMount(async () => {
-      const text = await historyFile.text().catch(() => "")
+      const text = await Filesystem.readText(historyPath).catch(() => "")
       const lines = text
         .split("\n")
         .filter(Boolean)
@@ -51,7 +52,7 @@ export const { use: usePromptHistory, provider: PromptHistoryProvider } = create
       // Rewrite file with only valid entries to self-heal corruption
       if (lines.length > 0) {
         const content = lines.map((line) => JSON.stringify(line)).join("\n") + "\n"
-        writeFile(historyFile.name!, content).catch(() => {})
+        writeFile(historyPath, content).catch(() => {})
       }
     })
 
@@ -97,11 +98,11 @@ export const { use: usePromptHistory, provider: PromptHistoryProvider } = create
 
         if (trimmed) {
           const content = store.history.map((line) => JSON.stringify(line)).join("\n") + "\n"
-          writeFile(historyFile.name!, content).catch(() => {})
+          writeFile(historyPath, content).catch(() => {})
           return
         }
 
-        appendFile(historyFile.name!, JSON.stringify(entry) + "\n").catch(() => {})
+        appendFile(historyPath, JSON.stringify(entry) + "\n").catch(() => {})
       },
     }
   },

packages/opencode/src/cli/cmd/tui/component/prompt/index.tsx

@@ -1,6 +1,8 @@
 import { BoxRenderable, TextareaRenderable, MouseEvent, PasteEvent, t, dim, fg } from "@opentui/core"
 import { createEffect, createMemo, type JSX, onMount, createSignal, onCleanup, on, Show, Switch, Match } from "solid-js"
 import "opentui-spinner/solid"
+import path from "path"
+import { Filesystem } from "@/util/filesystem"
 import { useLocal } from "@tui/context/local"
 import { useTheme } from "@tui/context/theme"
 import { EmptyBorder } from "@tui/component/border"
@@ -931,26 +933,26 @@ export function Prompt(props: PromptProps) {
                 const isUrl = /^(https?):\/\//.test(filepath)
                 if (!isUrl) {
                   try {
-                    const file = Bun.file(filepath)
+                    const mime = Filesystem.mimeType(filepath)
+                    const filename = path.basename(filepath)
                     // Handle SVG as raw text content, not as base64 image
-                    if (file.type === "image/svg+xml") {
+                    if (mime === "image/svg+xml") {
                       event.preventDefault()
-                      const content = await file.text().catch(() => {})
+                      const content = await Filesystem.readText(filepath).catch(() => {})
                       if (content) {
-                        pasteText(content, `[SVG: ${file.name ?? "image"}]`)
+                        pasteText(content, `[SVG: ${filename ?? "image"}]`)
                         return
                       }
                     }
-                    if (file.type.startsWith("image/")) {
+                    if (mime.startsWith("image/")) {
                       event.preventDefault()
-                      const content = await file
+                      const content = await Filesystem.readArrayBuffer(filepath)
-                        .arrayBuffer()
                         .then((buffer) => Buffer.from(buffer).toString("base64"))
                         .catch(() => {})
                       if (content) {
                         await pasteImage({
-                          filename: file.name,
+                          filename,
-                          mime: file.type,
+                          mime,
                           content,
                         })
                         return

packages/opencode/src/cli/cmd/tui/component/prompt/stash.tsx

@@ -1,5 +1,6 @@
 import path from "path"
 import { Global } from "@/global"
+import { Filesystem } from "@/util/filesystem"
 import { onMount } from "solid-js"
 import { createStore, produce } from "solid-js/store"
 import { clone } from "remeda"
@@ -18,9 +19,9 @@ const MAX_STASH_ENTRIES = 50
 export const { use: usePromptStash, provider: PromptStashProvider } = createSimpleContext({
   name: "PromptStash",
   init: () => {
-    const stashFile = Bun.file(path.join(Global.Path.state, "prompt-stash.jsonl"))
+    const stashPath = path.join(Global.Path.state, "prompt-stash.jsonl")
     onMount(async () => {
-      const text = await stashFile.text().catch(() => "")
+      const text = await Filesystem.readText(stashPath).catch(() => "")
       const lines = text
         .split("\n")
         .filter(Boolean)
@@ -39,7 +40,7 @@ export const { use: usePromptStash, provider: PromptStashProvider } = createSimp
       // Rewrite file with only valid entries to self-heal corruption
       if (lines.length > 0) {
         const content = lines.map((line) => JSON.stringify(line)).join("\n") + "\n"
-        writeFile(stashFile.name!, content).catch(() => {})
+        writeFile(stashPath, content).catch(() => {})
       }
     })
 
@@ -66,11 +67,11 @@ export const { use: usePromptStash, provider: PromptStashProvider } = createSimp
 
         if (trimmed) {
           const content = store.entries.map((line) => JSON.stringify(line)).join("\n") + "\n"
-          writeFile(stashFile.name!, content).catch(() => {})
+          writeFile(stashPath, content).catch(() => {})
           return
         }
 
-        appendFile(stashFile.name!, JSON.stringify(stash) + "\n").catch(() => {})
+        appendFile(stashPath, JSON.stringify(stash) + "\n").catch(() => {})
       },
       pop() {
         if (store.entries.length === 0) return undefined
@@ -82,7 +83,7 @@ export const { use: usePromptStash, provider: PromptStashProvider } = createSimp
         )
         const content =
           store.entries.length > 0 ? store.entries.map((line) => JSON.stringify(line)).join("\n") + "\n" : ""
-        writeFile(stashFile.name!, content).catch(() => {})
+        writeFile(stashPath, content).catch(() => {})
         return entry
       },
       remove(index: number) {
@@ -94,7 +95,7 @@ export const { use: usePromptStash, provider: PromptStashProvider } = createSimp
         )
         const content =
           store.entries.length > 0 ? store.entries.map((line) => JSON.stringify(line)).join("\n") + "\n" : ""
-        writeFile(stashFile.name!, content).catch(() => {})
+        writeFile(stashPath, content).catch(() => {})
       },
     }
   },

packages/opencode/src/cli/cmd/tui/context/kv.tsx

@@ -1,4 +1,5 @@
 import { Global } from "@/global"
+import { Filesystem } from "@/util/filesystem"
 import { createSignal, type Setter } from "solid-js"
 import { createStore } from "solid-js/store"
 import { createSimpleContext } from "./helper"
@@ -9,10 +10,9 @@ export const { use: useKV, provider: KVProvider } = createSimpleContext({
   init: () => {
     const [ready, setReady] = createSignal(false)
     const [store, setStore] = createStore<Record<string, any>>()
-    const file = Bun.file(path.join(Global.Path.state, "kv.json"))
+    const filePath = path.join(Global.Path.state, "kv.json")
 
-    file
+    Filesystem.readJson(filePath)
-      .json()
       .then((x) => {
         setStore(x)
       })
@@ -44,7 +44,7 @@ export const { use: useKV, provider: KVProvider } = createSimpleContext({
       },
       set(key: string, value: any) {
         setStore(key, value)
-        Bun.write(file, JSON.stringify(store, null, 2))
+        Filesystem.writeJson(filePath, store)
       },
     }
     return result

packages/opencode/src/cli/cmd/tui/context/local.tsx

@@ -12,6 +12,7 @@ import { Provider } from "@/provider/provider"
 import { useArgs } from "./args"
 import { useSDK } from "./sdk"
 import { RGBA } from "@opentui/core"
+import { Filesystem } from "@/util/filesystem"
 
 export const { use: useLocal, provider: LocalProvider } = createSimpleContext({
   name: "Local",
@@ -119,7 +120,7 @@ export const { use: useLocal, provider: LocalProvider } = createSimpleContext({
         variant: {},
       })
 
-      const file = Bun.file(path.join(Global.Path.state, "model.json"))
+      const filePath = path.join(Global.Path.state, "model.json")
       const state = {
         pending: false,
       }
@@ -130,19 +131,15 @@ export const { use: useLocal, provider: LocalProvider } = createSimpleContext({
           return
         }
         state.pending = false
-        Bun.write(
+        Filesystem.writeJson(filePath, {
-          file,
+          recent: modelStore.recent,
-          JSON.stringify({
+          favorite: modelStore.favorite,
-            recent: modelStore.recent,
+          variant: modelStore.variant,
-            favorite: modelStore.favorite,
+        })
-            variant: modelStore.variant,
-          }),
-        )
       }
 
-      file
+      Filesystem.readJson(filePath)
-        .json()
+        .then((x: any) => {
-        .then((x) => {
           if (Array.isArray(x.recent)) setModelStore("recent", x.recent)
           if (Array.isArray(x.favorite)) setModelStore("favorite", x.favorite)
           if (typeof x.variant === "object" && x.variant !== null) setModelStore("variant", x.variant)

packages/opencode/src/cli/cmd/tui/context/theme.tsx

@@ -412,7 +412,7 @@ async function getCustomThemes() {
       cwd: dir,
     })) {
       const name = path.basename(item, ".json")
-      result[name] = await Bun.file(item).json()
+      result[name] = await Filesystem.readJson(item)
     }
   }
   return result

packages/opencode/src/cli/cmd/tui/thread.ts

@@ -3,10 +3,12 @@ import { tui } from "./app"
 import { Rpc } from "@/util/rpc"
 import { type rpc } from "./worker"
 import path from "path"
+import { fileURLToPath } from "url"
 import { UI } from "@/cli/ui"
 import { iife } from "@/util/iife"
 import { Log } from "@/util/log"
 import { withNetworkOptions, resolveNetworkOptions } from "@/cli/network"
+import { Filesystem } from "@/util/filesystem"
 import type { Event } from "@opencode-ai/sdk/v2"
 import type { EventSource } from "./context/sdk"
 import { win32DisableProcessedInput, win32InstallCtrlCGuard } from "./win32"
@@ -99,7 +101,7 @@ export const TuiThreadCommand = cmd({
       const distWorker = new URL("./cli/cmd/tui/worker.js", import.meta.url)
       const workerPath = await iife(async () => {
         if (typeof OPENCODE_WORKER_PATH !== "undefined") return OPENCODE_WORKER_PATH
-        if (await Bun.file(distWorker).exists()) return distWorker
+        if (await Filesystem.exists(fileURLToPath(distWorker))) return distWorker
         return localWorker
       })
       try {

packages/opencode/src/lsp/client.ts

@@ -147,8 +147,7 @@ export namespace LSPClient {
       notify: {
         async open(input: { path: string }) {
           input.path = path.isAbsolute(input.path) ? input.path : path.resolve(Instance.directory, input.path)
-          const file = Bun.file(input.path)
+          const text = await Filesystem.readText(input.path)
-          const text = await file.text()
           const extension = path.extname(input.path)
           const languageId = LANGUAGE_EXTENSIONS[extension] ?? "plaintext"
 

packages/opencode/src/lsp/server.ts

@@ -131,7 +131,7 @@ export namespace LSPServer {
           "bin",
           "vue-language-server.js",
         )
-        if (!(await Bun.file(js).exists())) {
+        if (!(await Filesystem.exists(js))) {
           if (Flag.OPENCODE_DISABLE_LSP_DOWNLOAD) return
           await Bun.spawn([BunProc.which(), "install", "@vue/language-server"], {
             cwd: Global.Path.bin,
@@ -173,14 +173,14 @@ export namespace LSPServer {
       if (!eslint) return
       log.info("spawning eslint server")
       const serverPath = path.join(Global.Path.bin, "vscode-eslint", "server", "out", "eslintServer.js")
-      if (!(await Bun.file(serverPath).exists())) {
+      if (!(await Filesystem.exists(serverPath))) {
         if (Flag.OPENCODE_DISABLE_LSP_DOWNLOAD) return
         log.info("downloading and building VS Code ESLint server")
         const response = await fetch("https://github.com/microsoft/vscode-eslint/archive/refs/heads/main.zip")
         if (!response.ok) return
 
         const zipPath = path.join(Global.Path.bin, "vscode-eslint.zip")
-        await Bun.file(zipPath).write(response)
+        if (response.body) await Filesystem.writeStream(zipPath, response.body)
 
         const ok = await Archive.extractZip(zipPath, Global.Path.bin)
           .then(() => true)
@@ -242,7 +242,7 @@ export namespace LSPServer {
 
       const resolveBin = async (target: string) => {
         const localBin = path.join(root, target)
-        if (await Bun.file(localBin).exists()) return localBin
+        if (await Filesystem.exists(localBin)) return localBin
 
         const candidates = Filesystem.up({
           targets: [target],
@@ -326,7 +326,7 @@ export namespace LSPServer {
     async spawn(root) {
       const localBin = path.join(root, "node_modules", ".bin", "biome")
       let bin: string | undefined
-      if (await Bun.file(localBin).exists()) bin = localBin
+      if (await Filesystem.exists(localBin)) bin = localBin
       if (!bin) {
         const found = Bun.which("biome")
         if (found) bin = found
@@ -467,7 +467,7 @@ export namespace LSPServer {
         const potentialPythonPath = isWindows
           ? path.join(venvPath, "Scripts", "python.exe")
           : path.join(venvPath, "bin", "python")
-        if (await Bun.file(potentialPythonPath).exists()) {
+        if (await Filesystem.exists(potentialPythonPath)) {
           initialization["pythonPath"] = potentialPythonPath
           break
         }
@@ -479,7 +479,7 @@ export namespace LSPServer {
           const potentialTyPath = isWindows
             ? path.join(venvPath, "Scripts", "ty.exe")
             : path.join(venvPath, "bin", "ty")
-          if (await Bun.file(potentialTyPath).exists()) {
+          if (await Filesystem.exists(potentialTyPath)) {
             binary = potentialTyPath
             break
           }
@@ -511,7 +511,7 @@ export namespace LSPServer {
       const args = []
       if (!binary) {
         const js = path.join(Global.Path.bin, "node_modules", "pyright", "dist", "pyright-langserver.js")
-        if (!(await Bun.file(js).exists())) {
+        if (!(await Filesystem.exists(js))) {
           if (Flag.OPENCODE_DISABLE_LSP_DOWNLOAD) return
           await Bun.spawn([BunProc.which(), "install", "pyright"], {
             cwd: Global.Path.bin,
@@ -536,7 +536,7 @@ export namespace LSPServer {
         const potentialPythonPath = isWindows
           ? path.join(venvPath, "Scripts", "python.exe")
           : path.join(venvPath, "bin", "python")
-        if (await Bun.file(potentialPythonPath).exists()) {
+        if (await Filesystem.exists(potentialPythonPath)) {
           initialization["pythonPath"] = potentialPythonPath
           break
         }
@@ -571,7 +571,7 @@ export namespace LSPServer {
           process.platform === "win32" ? "language_server.bat" : "language_server.sh",
         )
 
-        if (!(await Bun.file(binary).exists())) {
+        if (!(await Filesystem.exists(binary))) {
           const elixir = Bun.which("elixir")
           if (!elixir) {
             log.error("elixir is required to run elixir-ls")
@@ -584,7 +584,7 @@ export namespace LSPServer {
           const response = await fetch("https://github.com/elixir-lsp/elixir-ls/archive/refs/heads/master.zip")
           if (!response.ok) return
           const zipPath = path.join(Global.Path.bin, "elixir-ls.zip")
-          await Bun.file(zipPath).write(response)
+          if (response.body) await Filesystem.writeStream(zipPath, response.body)
 
           const ok = await Archive.extractZip(zipPath, Global.Path.bin)
             .then(() => true)
@@ -692,7 +692,7 @@ export namespace LSPServer {
         }
 
         const tempPath = path.join(Global.Path.bin, assetName)
-        await Bun.file(tempPath).write(downloadResponse)
+        if (downloadResponse.body) await Filesystem.writeStream(tempPath, downloadResponse.body)
 
         if (ext === "zip") {
           const ok = await Archive.extractZip(tempPath, Global.Path.bin)
@@ -710,7 +710,7 @@ export namespace LSPServer {
 
         bin = path.join(Global.Path.bin, "zls" + (platform === "win32" ? ".exe" : ""))
 
-        if (!(await Bun.file(bin).exists())) {
+        if (!(await Filesystem.exists(bin))) {
           log.error("Failed to extract zls binary")
           return
         }
@@ -857,7 +857,7 @@ export namespace LSPServer {
         // Stop at filesystem root
         const cargoTomlPath = path.join(currentDir, "Cargo.toml")
         try {
-          const cargoTomlContent = await Bun.file(cargoTomlPath).text()
+          const cargoTomlContent = await Filesystem.readText(cargoTomlPath)
           if (cargoTomlContent.includes("[workspace]")) {
             return currentDir
           }
@@ -907,7 +907,7 @@ export namespace LSPServer {
 
       const ext = process.platform === "win32" ? ".exe" : ""
       const direct = path.join(Global.Path.bin, "clangd" + ext)
-      if (await Bun.file(direct).exists()) {
+      if (await Filesystem.exists(direct)) {
         return {
           process: spawn(direct, args, {
             cwd: root,
@@ -920,7 +920,7 @@ export namespace LSPServer {
         if (!entry.isDirectory()) continue
         if (!entry.name.startsWith("clangd_")) continue
         const candidate = path.join(Global.Path.bin, entry.name, "bin", "clangd" + ext)
-        if (await Bun.file(candidate).exists()) {
+        if (await Filesystem.exists(candidate)) {
           return {
             process: spawn(candidate, args, {
               cwd: root,
@@ -990,7 +990,7 @@ export namespace LSPServer {
         log.error("Failed to write clangd archive")
         return
       }
-      await Bun.write(archive, buf)
+      await Filesystem.write(archive, Buffer.from(buf))
 
       const zip = name.endsWith(".zip")
       const tar = name.endsWith(".tar.xz")
@@ -1014,7 +1014,7 @@ export namespace LSPServer {
       await fs.rm(archive, { force: true })
 
       const bin = path.join(Global.Path.bin, "clangd_" + tag, "bin", "clangd" + ext)
-      if (!(await Bun.file(bin).exists())) {
+      if (!(await Filesystem.exists(bin))) {
         log.error("Failed to extract clangd binary")
         return
       }
@@ -1045,7 +1045,7 @@ export namespace LSPServer {
       const args: string[] = []
       if (!binary) {
         const js = path.join(Global.Path.bin, "node_modules", "svelte-language-server", "bin", "server.js")
-        if (!(await Bun.file(js).exists())) {
+        if (!(await Filesystem.exists(js))) {
           if (Flag.OPENCODE_DISABLE_LSP_DOWNLOAD) return
           await Bun.spawn([BunProc.which(), "install", "svelte-language-server"], {
             cwd: Global.Path.bin,
@@ -1092,7 +1092,7 @@ export namespace LSPServer {
       const args: string[] = []
       if (!binary) {
         const js = path.join(Global.Path.bin, "node_modules", "@astrojs", "language-server", "bin", "nodeServer.js")
-        if (!(await Bun.file(js).exists())) {
+        if (!(await Filesystem.exists(js))) {
           if (Flag.OPENCODE_DISABLE_LSP_DOWNLOAD) return
           await Bun.spawn([BunProc.which(), "install", "@astrojs/language-server"], {
             cwd: Global.Path.bin,
@@ -1248,7 +1248,7 @@ export namespace LSPServer {
       const distPath = path.join(Global.Path.bin, "kotlin-ls")
       const launcherScript =
         process.platform === "win32" ? path.join(distPath, "kotlin-lsp.cmd") : path.join(distPath, "kotlin-lsp.sh")
-      const installed = await Bun.file(launcherScript).exists()
+      const installed = await Filesystem.exists(launcherScript)
       if (!installed) {
         if (Flag.OPENCODE_DISABLE_LSP_DOWNLOAD) return
         log.info("Downloading Kotlin Language Server from GitHub.")
@@ -1307,7 +1307,7 @@ export namespace LSPServer {
         }
         log.info("Installed Kotlin Language Server", { path: launcherScript })
       }
-      if (!(await Bun.file(launcherScript).exists())) {
+      if (!(await Filesystem.exists(launcherScript))) {
         log.error(`Failed to locate the Kotlin LS launcher script in the installed directory: ${distPath}.`)
         return
       }
@@ -1336,7 +1336,7 @@ export namespace LSPServer {
           "src",
           "server.js",
         )
-        const exists = await Bun.file(js).exists()
+        const exists = await Filesystem.exists(js)
         if (!exists) {
           if (Flag.OPENCODE_DISABLE_LSP_DOWNLOAD) return
           await Bun.spawn([BunProc.which(), "install", "yaml-language-server"], {
@@ -1443,7 +1443,7 @@ export namespace LSPServer {
         }
 
         const tempPath = path.join(Global.Path.bin, assetName)
-        await Bun.file(tempPath).write(downloadResponse)
+        if (downloadResponse.body) await Filesystem.writeStream(tempPath, downloadResponse.body)
 
         // Unlike zls which is a single self-contained binary,
         // lua-language-server needs supporting files (meta/, locale/, etc.)
@@ -1482,7 +1482,7 @@ export namespace LSPServer {
         // Binary is located in bin/ subdirectory within the extracted archive
         bin = path.join(installDir, "bin", "lua-language-server" + (platform === "win32" ? ".exe" : ""))
 
-        if (!(await Bun.file(bin).exists())) {
+        if (!(await Filesystem.exists(bin))) {
           log.error("Failed to extract lua-language-server binary")
           return
         }
@@ -1516,7 +1516,7 @@ export namespace LSPServer {
       const args: string[] = []
       if (!binary) {
         const js = path.join(Global.Path.bin, "node_modules", "intelephense", "lib", "intelephense.js")
-        if (!(await Bun.file(js).exists())) {
+        if (!(await Filesystem.exists(js))) {
           if (Flag.OPENCODE_DISABLE_LSP_DOWNLOAD) return
           await Bun.spawn([BunProc.which(), "install", "intelephense"], {
             cwd: Global.Path.bin,
@@ -1613,7 +1613,7 @@ export namespace LSPServer {
       const args: string[] = []
       if (!binary) {
         const js = path.join(Global.Path.bin, "node_modules", "bash-language-server", "out", "cli.js")
-        if (!(await Bun.file(js).exists())) {
+        if (!(await Filesystem.exists(js))) {
           if (Flag.OPENCODE_DISABLE_LSP_DOWNLOAD) return
           await Bun.spawn([BunProc.which(), "install", "bash-language-server"], {
             cwd: Global.Path.bin,
@@ -1654,22 +1654,17 @@ export namespace LSPServer {
 
       if (!bin) {
         if (Flag.OPENCODE_DISABLE_LSP_DOWNLOAD) return
-        log.info("downloading terraform-ls from GitHub releases")
+        log.info("downloading terraform-ls from HashiCorp releases")
 
-        const releaseResponse = await fetch("https://api.github.com/repos/hashicorp/terraform-ls/releases/latest")
+        const releaseResponse = await fetch("https://api.releases.hashicorp.com/v1/releases/terraform-ls/latest")
         if (!releaseResponse.ok) {
           log.error("Failed to fetch terraform-ls release info")
           return
         }
 
         const release = (await releaseResponse.json()) as {
-          tag_name?: string
+          version?: string
-          assets?: { name?: string; browser_download_url?: string }[]
+          builds?: { arch?: string; os?: string; url?: string }[]
-        }
-        const version = release.tag_name?.replace("v", "")
-        if (!version) {
-          log.error("terraform-ls release did not include a version tag")
-          return
         }
 
         const platform = process.platform
@@ -1678,23 +1673,21 @@ export namespace LSPServer {
         const tfArch = arch === "arm64" ? "arm64" : "amd64"
         const tfPlatform = platform === "win32" ? "windows" : platform
 
-        const assetName = `terraform-ls_${version}_${tfPlatform}_${tfArch}.zip`
+        const builds = release.builds ?? []
-
+        const build = builds.find((b) => b.arch === tfArch && b.os === tfPlatform)
-        const assets = release.assets ?? []
+        if (!build?.url) {
-        const asset = assets.find((a) => a.name === assetName)
+          log.error(`Could not find build for ${tfPlatform}/${tfArch} terraform-ls release version ${release.version}`)
-        if (!asset?.browser_download_url) {
-          log.error(`Could not find asset ${assetName} in terraform-ls release`)
           return
         }
 
-        const downloadResponse = await fetch(asset.browser_download_url)
+        const downloadResponse = await fetch(build.url)
         if (!downloadResponse.ok) {
           log.error("Failed to download terraform-ls")
           return
         }
 
-        const tempPath = path.join(Global.Path.bin, assetName)
+        const tempPath = path.join(Global.Path.bin, "terraform-ls.zip")
-        await Bun.file(tempPath).write(downloadResponse)
+        if (downloadResponse.body) await Filesystem.writeStream(tempPath, downloadResponse.body)
 
         const ok = await Archive.extractZip(tempPath, Global.Path.bin)
           .then(() => true)
@@ -1707,7 +1700,7 @@ export namespace LSPServer {
 
         bin = path.join(Global.Path.bin, "terraform-ls" + (platform === "win32" ? ".exe" : ""))
 
-        if (!(await Bun.file(bin).exists())) {
+        if (!(await Filesystem.exists(bin))) {
           log.error("Failed to extract terraform-ls binary")
           return
         }
@@ -1784,7 +1777,7 @@ export namespace LSPServer {
         }
 
         const tempPath = path.join(Global.Path.bin, assetName)
-        await Bun.file(tempPath).write(downloadResponse)
+        if (downloadResponse.body) await Filesystem.writeStream(tempPath, downloadResponse.body)
 
         if (ext === "zip") {
           const ok = await Archive.extractZip(tempPath, Global.Path.bin)
@@ -1803,7 +1796,7 @@ export namespace LSPServer {
 
         bin = path.join(Global.Path.bin, "texlab" + (platform === "win32" ? ".exe" : ""))
 
-        if (!(await Bun.file(bin).exists())) {
+        if (!(await Filesystem.exists(bin))) {
           log.error("Failed to extract texlab binary")
           return
         }
@@ -1832,7 +1825,7 @@ export namespace LSPServer {
       const args: string[] = []
       if (!binary) {
         const js = path.join(Global.Path.bin, "node_modules", "dockerfile-language-server-nodejs", "lib", "server.js")
-        if (!(await Bun.file(js).exists())) {
+        if (!(await Filesystem.exists(js))) {
           if (Flag.OPENCODE_DISABLE_LSP_DOWNLOAD) return
           await Bun.spawn([BunProc.which(), "install", "dockerfile-language-server-nodejs"], {
             cwd: Global.Path.bin,
@@ -1990,7 +1983,7 @@ export namespace LSPServer {
         }
 
         const tempPath = path.join(Global.Path.bin, assetName)
-        await Bun.file(tempPath).write(downloadResponse)
+        if (downloadResponse.body) await Filesystem.writeStream(tempPath, downloadResponse.body)
 
         if (ext === "zip") {
           const ok = await Archive.extractZip(tempPath, Global.Path.bin)
@@ -2008,7 +2001,7 @@ export namespace LSPServer {
 
         bin = path.join(Global.Path.bin, "tinymist" + (platform === "win32" ? ".exe" : ""))
 
-        if (!(await Bun.file(bin).exists())) {
+        if (!(await Filesystem.exists(bin))) {
           log.error("Failed to extract tinymist binary")
           return
         }

packages/opencode/src/mcp/auth.ts

@@ -1,6 +1,7 @@
 import path from "path"
 import z from "zod"
 import { Global } from "../global"
+import { Filesystem } from "../util/filesystem"
 
 export namespace McpAuth {
   export const Tokens = z.object({
@@ -53,25 +54,22 @@ export namespace McpAuth {
   }
 
   export async function all(): Promise<Record<string, Entry>> {
-    const file = Bun.file(filepath)
+    return Filesystem.readJson<Record<string, Entry>>(filepath).catch(() => ({}))
-    return file.json().catch(() => ({}))
   }
 
   export async function set(mcpName: string, entry: Entry, serverUrl?: string): Promise<void> {
-    const file = Bun.file(filepath)
     const data = await all()
     // Always update serverUrl if provided
     if (serverUrl) {
       entry.serverUrl = serverUrl
     }
-    await Bun.write(file, JSON.stringify({ ...data, [mcpName]: entry }, null, 2), { mode: 0o600 })
+    await Filesystem.writeJson(filepath, { ...data, [mcpName]: entry }, 0o600)
   }
 
   export async function remove(mcpName: string): Promise<void> {
-    const file = Bun.file(filepath)
     const data = await all()
     delete data[mcpName]
-    await Bun.write(file, JSON.stringify(data, null, 2), { mode: 0o600 })
+    await Filesystem.writeJson(filepath, data, 0o600)
   }
 
   export async function updateTokens(mcpName: string, tokens: Tokens, serverUrl?: string): Promise<void> {

packages/opencode/src/project/project.ts

@@ -86,8 +86,7 @@ export namespace Project {
         const gitBinary = Bun.which("git")
 
         // cached id calculation
-        let id = await Bun.file(path.join(dotgit, "opencode"))
+        let id = await Filesystem.readText(path.join(dotgit, "opencode"))
-          .text()
           .then((x) => x.trim())
           .catch(() => undefined)
 
@@ -125,9 +124,7 @@ export namespace Project {
 
           id = roots[0]
           if (id) {
-            void Bun.file(path.join(dotgit, "opencode"))
+            void Filesystem.write(path.join(dotgit, "opencode"), id).catch(() => undefined)
-              .write(id)
-              .catch(() => undefined)
           }
         }
 
@@ -277,10 +274,9 @@ export namespace Project {
     )
     const shortest = matches.sort((a, b) => a.length - b.length)[0]
     if (!shortest) return
-    const file = Bun.file(shortest)
+    const buffer = await Filesystem.readBytes(shortest)
-    const buffer = await file.arrayBuffer()
+    const base64 = buffer.toString("base64")
-    const base64 = Buffer.from(buffer).toString("base64")
+    const mime = Filesystem.mimeType(shortest) || "image/png"
-    const mime = file.type || "image/png"
     const url = `data:${mime};base64,${base64}`
     await update({
       projectID: input.id,
@@ -381,10 +377,8 @@ export namespace Project {
     const data = fromRow(row)
     const valid: string[] = []
     for (const dir of data.sandboxes) {
-      const stat = await Bun.file(dir)
+      const s = Filesystem.stat(dir)
-        .stat()
+      if (s?.isDirectory()) valid.push(dir)
-        .catch(() => undefined)
-      if (stat?.isDirectory()) valid.push(dir)
     }
     return valid
   }

packages/opencode/src/provider/models.ts

@@ -5,6 +5,7 @@ import z from "zod"
 import { Installation } from "../installation"
 import { Flag } from "../flag/flag"
 import { lazy } from "@/util/lazy"
+import { Filesystem } from "../util/filesystem"
 
 // Try to import bundled snapshot (generated at build time)
 // Falls back to undefined in dev mode when snapshot doesn't exist
@@ -85,8 +86,7 @@ export namespace ModelsDev {
   }
 
   export const Data = lazy(async () => {
-    const file = Bun.file(Flag.OPENCODE_MODELS_PATH ?? filepath)
+    const result = await Filesystem.readJson(Flag.OPENCODE_MODELS_PATH ?? filepath).catch(() => {})
-    const result = await file.json().catch(() => {})
     if (result) return result
     // @ts-ignore
     const snapshot = await import("./models-snapshot")
@@ -104,7 +104,6 @@ export namespace ModelsDev {
   }
 
   export async function refresh() {
-    const file = Bun.file(filepath)
     const result = await fetch(`${url()}/api.json`, {
       headers: {
         "User-Agent": Installation.USER_AGENT,
@@ -116,7 +115,7 @@ export namespace ModelsDev {
       })
     })
     if (result && result.ok) {
-      await Bun.write(file, await result.text())
+      await Filesystem.write(filepath, await result.text())
       ModelsDev.Data.reset()
     }
   }

packages/opencode/src/provider/provider.ts

@@ -16,6 +16,7 @@ import { Flag } from "../flag/flag"
 import { iife } from "@/util/iife"
 import { Global } from "../global"
 import path from "path"
+import { Filesystem } from "../util/filesystem"
 
 // Direct imports for bundled providers
 import { createAmazonBedrock, type AmazonBedrockProviderSettings } from "@ai-sdk/amazon-bedrock"
@@ -1289,8 +1290,9 @@ export namespace Provider {
     if (cfg.model) return parseModel(cfg.model)
 
     const providers = await list()
-    const recent = (await Bun.file(path.join(Global.Path.state, "model.json"))
+    const recent = (await Filesystem.readJson<{ recent?: { providerID: string; modelID: string }[] }>(
-      .json()
+      path.join(Global.Path.state, "model.json"),
+    )
       .then((x) => (Array.isArray(x.recent) ? x.recent : []))
       .catch(() => [])) as { providerID: string; modelID: string }[]
     for (const entry of recent) {

packages/opencode/src/session/instruction.ts

@@ -85,7 +85,7 @@ export namespace InstructionPrompt {
     }
 
     for (const file of globalFiles()) {
-      if (await Bun.file(file).exists()) {
+      if (await Filesystem.exists(file)) {
         paths.add(path.resolve(file))
         break
       }
@@ -120,9 +120,7 @@ export namespace InstructionPrompt {
     const paths = await systemPaths()
 
     const files = Array.from(paths).map(async (p) => {
-      const content = await Bun.file(p)
+      const content = await Filesystem.readText(p).catch(() => "")
-        .text()
-        .catch(() => "")
       return content ? "Instructions from: " + p + "\n" + content : ""
     })
 
@@ -164,7 +162,7 @@ export namespace InstructionPrompt {
   export async function find(dir: string) {
     for (const file of FILES) {
       const filepath = path.resolve(path.join(dir, file))
-      if (await Bun.file(filepath).exists()) return filepath
+      if (await Filesystem.exists(filepath)) return filepath
     }
   }
 
@@ -182,9 +180,7 @@ export namespace InstructionPrompt {
 
       if (found && found !== target && !system.has(found) && !already.has(found) && !isClaimed(messageID, found)) {
         claim(messageID, found)
-        const content = await Bun.file(found)
+        const content = await Filesystem.readText(found).catch(() => undefined)
-          .text()
-          .catch(() => undefined)
         if (content) {
           results.push({ filepath: found, content: "Instructions from: " + found + "\n" + content })
         }

packages/opencode/src/session/prompt.ts

@@ -2,6 +2,7 @@ import path from "path"
 import os from "os"
 import fs from "fs/promises"
 import z from "zod"
+import { Filesystem } from "../util/filesystem"
 import { Identifier } from "../id/id"
 import { MessageV2 } from "./message-v2"
 import { Log } from "../util/log"
@@ -1082,11 +1083,9 @@ export namespace SessionPrompt {
               // have to normalize, symbol search returns absolute paths
               // Decode the pathname since URL constructor doesn't automatically decode it
               const filepath = fileURLToPath(part.url)
-              const stat = await Bun.file(filepath)
+              const s = Filesystem.stat(filepath)
-                .stat()
-                .catch(() => undefined)
 
-              if (stat?.isDirectory()) {
+              if (s?.isDirectory()) {
                 part.mime = "application/x-directory"
               }
 
@@ -1233,14 +1232,13 @@ export namespace SessionPrompt {
                 ]
               }
 
-              const file = Bun.file(filepath)
               FileTime.read(input.sessionID, filepath)
               return [
                 {
                   messageID: info.id,
                   sessionID: input.sessionID,
                   type: "text",
-                  text: `Called the Read tool with the following input: {\"filePath\":\"${filepath}\"}`,
+                  text: `Called the Read tool with the following input: {"filePath":"${filepath}"}`,
                   synthetic: true,
                 },
                 {
@@ -1248,7 +1246,7 @@ export namespace SessionPrompt {
                   messageID: info.id,
                   sessionID: input.sessionID,
                   type: "file",
-                  url: `data:${part.mime};base64,` + Buffer.from(await file.bytes()).toString("base64"),
+                  url: `data:${part.mime};base64,` + (await Filesystem.readBytes(filepath)).toString("base64"),
                   mime: part.mime,
                   filename: part.filename!,
                   source: part.source,
@@ -1354,7 +1352,7 @@ export namespace SessionPrompt {
     // Switching from plan mode to build mode
     if (input.agent.name !== "plan" && assistantMessage?.info.agent === "plan") {
       const plan = Session.plan(input.session)
-      const exists = await Bun.file(plan).exists()
+      const exists = await Filesystem.exists(plan)
       if (exists) {
         const part = await Session.updatePart({
           id: Identifier.ascending("part"),
@@ -1373,7 +1371,7 @@ export namespace SessionPrompt {
     // Entering plan mode
     if (input.agent.name === "plan" && assistantMessage?.info.agent !== "plan") {
       const plan = Session.plan(input.session)
-      const exists = await Bun.file(plan).exists()
+      const exists = await Filesystem.exists(plan)
       if (!exists) await fs.mkdir(path.dirname(plan), { recursive: true })
       const part = await Session.updatePart({
         id: Identifier.ascending("part"),

packages/opencode/src/shell/shell.ts

@@ -1,5 +1,6 @@
 import { Flag } from "@/flag/flag"
 import { lazy } from "@/util/lazy"
+import { Filesystem } from "@/util/filesystem"
 import path from "path"
 import { spawn, type ChildProcess } from "child_process"
 
@@ -43,7 +44,7 @@ export namespace Shell {
         // git.exe is typically at: C:\Program Files\Git\cmd\git.exe
         // bash.exe is at: C:\Program Files\Git\bin\bash.exe
         const bash = path.join(git, "..", "..", "bin", "bash.exe")
-        if (Bun.file(bash).size) return bash
+        if (Filesystem.stat(bash)?.size) return bash
       }
       return process.env.COMSPEC || "cmd.exe"
     }

packages/opencode/src/skill/discovery.ts

@@ -2,6 +2,7 @@ import path from "path"
 import { mkdir } from "fs/promises"
 import { Log } from "../util/log"
 import { Global } from "../global"
+import { Filesystem } from "../util/filesystem"
 
 export namespace Discovery {
   const log = Log.create({ service: "skill-discovery" })
@@ -19,14 +20,14 @@ export namespace Discovery {
   }
 
   async function get(url: string, dest: string): Promise<boolean> {
-    if (await Bun.file(dest).exists()) return true
+    if (await Filesystem.exists(dest)) return true
     return fetch(url)
       .then(async (response) => {
         if (!response.ok) {
           log.error("failed to download", { url, status: response.status })
           return false
         }
-        await Bun.write(dest, await response.text())
+        if (response.body) await Filesystem.writeStream(dest, response.body)
         return true
       })
       .catch((err) => {
@@ -88,7 +89,7 @@ export namespace Discovery {
         )
 
         const md = path.join(root, "SKILL.md")
-        if (await Bun.file(md).exists()) result.push(root)
+        if (await Filesystem.exists(md)) result.push(root)
       }),
     )
 

packages/opencode/src/storage/db.ts

@@ -10,7 +10,7 @@ import { Log } from "../util/log"
 import { NamedError } from "@opencode-ai/util/error"
 import z from "zod"
 import path from "path"
-import { readFileSync, readdirSync } from "fs"
+import { readFileSync, readdirSync, existsSync } from "fs"
 import * as schema from "./schema"
 
 declare const OPENCODE_MIGRATIONS: { sql: string; timestamp: number }[] | undefined
@@ -54,7 +54,7 @@ export namespace Database {
     const sql = dirs
       .map((name) => {
         const file = path.join(dir, name, "migration.sql")
-        if (!Bun.file(file).size) return
+        if (!existsSync(file)) return
         return {
           sql: readFileSync(file, "utf-8"),
           timestamp: time(name),

packages/opencode/src/storage/json-migration.ts

@@ -7,6 +7,7 @@ import { SessionTable, MessageTable, PartTable, TodoTable, PermissionTable } fro
 import { SessionShareTable } from "../share/share.sql"
 import path from "path"
 import { existsSync } from "fs"
+import { Filesystem } from "../util/filesystem"
 
 export namespace JsonMigration {
   const log = Log.create({ service: "json-migration" })
@@ -82,7 +83,7 @@ export namespace JsonMigration {
       const count = end - start
       const tasks = new Array(count)
       for (let i = 0; i < count; i++) {
-        tasks[i] = Bun.file(files[start + i]).json()
+        tasks[i] = Filesystem.readJson(files[start + i])
       }
       const results = await Promise.allSettled(tasks)
       const items = new Array(count)

packages/opencode/src/storage/storage.ts

@@ -39,7 +39,7 @@ export namespace Storage {
             cwd: path.join(project, projectDir),
             absolute: true,
           })) {
-            const json = await Bun.file(msgFile).json()
+            const json = await Filesystem.readJson<any>(msgFile)
             worktree = json.path?.root
             if (worktree) break
           }
@@ -60,18 +60,15 @@ export namespace Storage {
           if (!id) continue
           projectID = id
 
-          await Bun.write(
+          await Filesystem.writeJson(path.join(dir, "project", projectID + ".json"), {
-            path.join(dir, "project", projectID + ".json"),
+            id,
-            JSON.stringify({
+            vcs: "git",
-              id,
+            worktree,
-              vcs: "git",
+            time: {
-              worktree,
+              created: Date.now(),
-              time: {
+              initialized: Date.now(),
-                created: Date.now(),
+            },
-                initialized: Date.now(),
+          })
-              },
-            }),
-          )
 
           log.info(`migrating sessions for project ${projectID}`)
           for await (const sessionFile of new Bun.Glob("storage/session/info/*.json").scan({
@@ -83,8 +80,8 @@ export namespace Storage {
               sessionFile,
               dest,
             })
-            const session = await Bun.file(sessionFile).json()
+            const session = await Filesystem.readJson<any>(sessionFile)
-            await Bun.write(dest, JSON.stringify(session))
+            await Filesystem.writeJson(dest, session)
             log.info(`migrating messages for session ${session.id}`)
             for await (const msgFile of new Bun.Glob(`storage/session/message/${session.id}/*.json`).scan({
               cwd: fullProjectDir,
@@ -95,8 +92,8 @@ export namespace Storage {
                 msgFile,
                 dest,
               })
-              const message = await Bun.file(msgFile).json()
+              const message = await Filesystem.readJson<any>(msgFile)
-              await Bun.write(dest, JSON.stringify(message))
+              await Filesystem.writeJson(dest, message)
 
               log.info(`migrating parts for message ${message.id}`)
               for await (const partFile of new Bun.Glob(`storage/session/part/${session.id}/${message.id}/*.json`).scan(
@@ -106,12 +103,12 @@ export namespace Storage {
                 },
               )) {
                 const dest = path.join(dir, "part", message.id, path.basename(partFile))
-                const part = await Bun.file(partFile).json()
+                const part = await Filesystem.readJson(partFile)
                 log.info("copying", {
                   partFile,
                   dest,
                 })
-                await Bun.write(dest, JSON.stringify(part))
+                await Filesystem.writeJson(dest, part)
               }
             }
           }
@@ -123,35 +120,32 @@ export namespace Storage {
         cwd: dir,
         absolute: true,
       })) {
-        const session = await Bun.file(item).json()
+        const session = await Filesystem.readJson<any>(item)
         if (!session.projectID) continue
         if (!session.summary?.diffs) continue
         const { diffs } = session.summary
-        await Bun.file(path.join(dir, "session_diff", session.id + ".json")).write(JSON.stringify(diffs))
+        await Filesystem.write(path.join(dir, "session_diff", session.id + ".json"), JSON.stringify(diffs))
-        await Bun.file(path.join(dir, "session", session.projectID, session.id + ".json")).write(
+        await Filesystem.writeJson(path.join(dir, "session", session.projectID, session.id + ".json"), {
-          JSON.stringify({
+          ...session,
-            ...session,
+          summary: {
-            summary: {
+            additions: diffs.reduce((sum: any, x: any) => sum + x.additions, 0),
-              additions: diffs.reduce((sum: any, x: any) => sum + x.additions, 0),
+            deletions: diffs.reduce((sum: any, x: any) => sum + x.deletions, 0),
-              deletions: diffs.reduce((sum: any, x: any) => sum + x.deletions, 0),
+          },
-            },
+        })
-          }),
-        )
       }
     },
   ]
 
   const state = lazy(async () => {
     const dir = path.join(Global.Path.data, "storage")
-    const migration = await Bun.file(path.join(dir, "migration"))
+    const migration = await Filesystem.readJson<string>(path.join(dir, "migration"))
-      .json()
       .then((x) => parseInt(x))
       .catch(() => 0)
     for (let index = migration; index < MIGRATIONS.length; index++) {
       log.info("running migration", { index })
       const migration = MIGRATIONS[index]
       await migration(dir).catch(() => log.error("failed to run migration", { index }))
-      await Bun.write(path.join(dir, "migration"), (index + 1).toString())
+      await Filesystem.write(path.join(dir, "migration"), (index + 1).toString())
     }
     return {
       dir,
@@ -171,7 +165,7 @@ export namespace Storage {
     const target = path.join(dir, ...key) + ".json"
     return withErrorHandling(async () => {
       using _ = await Lock.read(target)
-      const result = await Bun.file(target).json()
+      const result = await Filesystem.readJson<T>(target)
       return result as T
     })
   }
@@ -181,10 +175,10 @@ export namespace Storage {
     const target = path.join(dir, ...key) + ".json"
     return withErrorHandling(async () => {
       using _ = await Lock.write(target)
-      const content = await Bun.file(target).json()
+      const content = await Filesystem.readJson<T>(target)
-      fn(content)
+      fn(content as T)
-      await Bun.write(target, JSON.stringify(content, null, 2))
+      await Filesystem.writeJson(target, content)
-      return content as T
+      return content
     })
   }
 
@@ -193,7 +187,7 @@ export namespace Storage {
     const target = path.join(dir, ...key) + ".json"
     return withErrorHandling(async () => {
       using _ = await Lock.write(target)
-      await Bun.write(target, JSON.stringify(content, null, 2))
+      await Filesystem.writeJson(target, content)
     })
   }
 

packages/opencode/src/tool/edit.ts

@@ -49,7 +49,7 @@ export const EditTool = Tool.define("edit", {
     let contentNew = ""
     await FileTime.withLock(filePath, async () => {
       if (params.oldString === "") {
-        const existed = await Bun.file(filePath).exists()
+        const existed = await Filesystem.exists(filePath)
         contentNew = params.newString
         diff = trimDiff(createTwoFilesPatch(filePath, filePath, contentOld, contentNew))
         await ctx.ask({
@@ -61,7 +61,7 @@ export const EditTool = Tool.define("edit", {
             diff,
           },
         })
-        await Bun.write(filePath, params.newString)
+        await Filesystem.write(filePath, params.newString)
         await Bus.publish(File.Event.Edited, {
           file: filePath,
         })
@@ -73,12 +73,11 @@ export const EditTool = Tool.define("edit", {
         return
       }
 
-      const file = Bun.file(filePath)
+      const stats = Filesystem.stat(filePath)
-      const stats = await file.stat().catch(() => {})
       if (!stats) throw new Error(`File ${filePath} not found`)
       if (stats.isDirectory()) throw new Error(`Path is a directory, not a file: ${filePath}`)
       await FileTime.assert(ctx.sessionID, filePath)
-      contentOld = await file.text()
+      contentOld = await Filesystem.readText(filePath)
       contentNew = replace(contentOld, params.oldString, params.newString, params.replaceAll)
 
       diff = trimDiff(
@@ -94,7 +93,7 @@ export const EditTool = Tool.define("edit", {
         },
       })
 
-      await file.write(contentNew)
+      await Filesystem.write(filePath, contentNew)
       await Bus.publish(File.Event.Edited, {
         file: filePath,
       })
@@ -102,7 +101,7 @@ export const EditTool = Tool.define("edit", {
         file: filePath,
         event: "change",
       })
-      contentNew = await file.text()
+      contentNew = await Filesystem.readText(filePath)
       diff = trimDiff(
         createTwoFilesPatch(filePath, filePath, normalizeLineEndings(contentOld), normalizeLineEndings(contentNew)),
       )

packages/opencode/src/tool/glob.ts

@@ -1,6 +1,7 @@
 import z from "zod"
 import path from "path"
 import { Tool } from "./tool"
+import { Filesystem } from "../util/filesystem"
 import DESCRIPTION from "./glob.txt"
 import { Ripgrep } from "../file/ripgrep"
 import { Instance } from "../project/instance"
@@ -45,10 +46,7 @@ export const GlobTool = Tool.define("glob", {
         break
       }
       const full = path.resolve(search, file)
-      const stats = await Bun.file(full)
+      const stats = Filesystem.stat(full)?.mtime.getTime() ?? 0
-        .stat()
-        .then((x) => x.mtime.getTime())
-        .catch(() => 0)
       files.push({
         path: full,
         mtime: stats,

packages/opencode/src/tool/grep.ts

@@ -1,5 +1,6 @@
 import z from "zod"
 import { Tool } from "./tool"
+import { Filesystem } from "../util/filesystem"
 import { Ripgrep } from "../file/ripgrep"
 
 import DESCRIPTION from "./grep.txt"
@@ -83,8 +84,7 @@ export const GrepTool = Tool.define("grep", {
       const lineNum = parseInt(lineNumStr, 10)
       const lineText = lineTextParts.join("|")
 
-      const file = Bun.file(filePath)
+      const stats = Filesystem.stat(filePath)
-      const stats = await file.stat().catch(() => null)
       if (!stats) continue
 
       matches.push({

packages/opencode/src/tool/lsp.ts

@@ -6,6 +6,7 @@ import DESCRIPTION from "./lsp.txt"
 import { Instance } from "../project/instance"
 import { pathToFileURL } from "url"
 import { assertExternalDirectory } from "./external-directory"
+import { Filesystem } from "../util/filesystem"
 
 const operations = [
   "goToDefinition",
@@ -47,7 +48,7 @@ export const LspTool = Tool.define("lsp", {
     const relPath = path.relative(Instance.worktree, file)
     const title = `${args.operation} ${relPath}:${args.line}:${args.character}`
 
-    const exists = await Bun.file(file).exists()
+    const exists = await Filesystem.exists(file)
     if (!exists) {
       throw new Error(`File not found: ${file}`)
     }

packages/opencode/src/tool/read.ts

@@ -10,6 +10,7 @@ import DESCRIPTION from "./read.txt"
 import { Instance } from "../project/instance"
 import { assertExternalDirectory } from "./external-directory"
 import { InstructionPrompt } from "../session/instruction"
+import { Filesystem } from "../util/filesystem"
 
 const DEFAULT_READ_LIMIT = 2000
 const MAX_LINE_LENGTH = 2000
@@ -34,8 +35,7 @@ export const ReadTool = Tool.define("read", {
     }
     const title = path.relative(Instance.worktree, filepath)
 
-    const file = Bun.file(filepath)
+    const stat = Filesystem.stat(filepath)
-    const stat = await file.stat().catch(() => undefined)
 
     await assertExternalDirectory(ctx, filepath, {
       bypass: Boolean(ctx.extra?.["bypassCwdCheck"]),
@@ -118,11 +118,10 @@ export const ReadTool = Tool.define("read", {
     const instructions = await InstructionPrompt.resolve(ctx.messages, filepath, ctx.messageID)
 
     // Exclude SVG (XML-based) and vnd.fastbidsheet (.fbs extension, commonly FlatBuffers schema files)
-    const isImage =
+    const mime = Filesystem.mimeType(filepath)
-      file.type.startsWith("image/") && file.type !== "image/svg+xml" && file.type !== "image/vnd.fastbidsheet"
+    const isImage = mime.startsWith("image/") && mime !== "image/svg+xml" && mime !== "image/vnd.fastbidsheet"
-    const isPdf = file.type === "application/pdf"
+    const isPdf = mime === "application/pdf"
     if (isImage || isPdf) {
-      const mime = file.type
       const msg = `${isImage ? "Image" : "PDF"} read successfully`
       return {
         title,
@@ -136,13 +135,13 @@ export const ReadTool = Tool.define("read", {
           {
             type: "file",
             mime,
-            url: `data:${mime};base64,${Buffer.from(await file.bytes()).toString("base64")}`,
+            url: `data:${mime};base64,${Buffer.from(await Filesystem.readBytes(filepath)).toString("base64")}`,
           },
         ],
       }
     }
 
-    const isBinary = await isBinaryFile(filepath, stat.size)
+    const isBinary = await isBinaryFile(filepath, Number(stat.size))
     if (isBinary) throw new Error(`Cannot read binary file: ${filepath}`)
 
     const stream = createReadStream(filepath, { encoding: "utf8" })

packages/opencode/src/tool/truncation.ts

@@ -5,6 +5,7 @@ import { Identifier } from "../id/id"
 import { PermissionNext } from "../permission/next"
 import type { Agent } from "../agent/agent"
 import { Scheduler } from "../scheduler"
+import { Filesystem } from "../util/filesystem"
 
 export namespace Truncate {
   export const MAX_LINES = 2000
@@ -91,7 +92,7 @@ export namespace Truncate {
 
     const id = Identifier.ascending("tool")
     const filepath = path.join(DIR, id)
-    await Bun.write(Bun.file(filepath), text)
+    await Filesystem.write(filepath, text)
 
     const hint = hasTaskTool(agent)
       ? `The tool call succeeded but the output was truncated. Full output saved to: ${filepath}\nUse the Task tool to have explore agent process this file with Grep and Read (with offset/limit). Do NOT read the full file yourself - delegate to save context.`

packages/opencode/src/tool/write.ts

@@ -26,9 +26,8 @@ export const WriteTool = Tool.define("write", {
     const filepath = path.isAbsolute(params.filePath) ? params.filePath : path.join(Instance.directory, params.filePath)
     await assertExternalDirectory(ctx, filepath)
 
-    const file = Bun.file(filepath)
+    const exists = await Filesystem.exists(filepath)
-    const exists = await file.exists()
+    const contentOld = exists ? await Filesystem.readText(filepath) : ""
-    const contentOld = exists ? await file.text() : ""
     if (exists) await FileTime.assert(ctx.sessionID, filepath)
 
     const diff = trimDiff(createTwoFilesPatch(filepath, filepath, contentOld, params.content))
@@ -42,7 +41,7 @@ export const WriteTool = Tool.define("write", {
       },
     })
 
-    await Bun.write(filepath, params.content)
+    await Filesystem.write(filepath, params.content)
     await Bus.publish(File.Event.Edited, {
       file: filepath,
     })

packages/opencode/src/util/filesystem.ts

@@ -1,8 +1,10 @@
-import { mkdir, readFile, writeFile } from "fs/promises"
+import { chmod, mkdir, readFile, writeFile } from "fs/promises"
-import { existsSync, statSync } from "fs"
+import { createWriteStream, existsSync, statSync } from "fs"
 import { lookup } from "mime-types"
 import { realpathSync } from "fs"
 import { dirname, join, relative } from "path"
+import { Readable } from "stream"
+import { pipeline } from "stream/promises"
 
 export namespace Filesystem {
   // Fast sync version for metadata checks
@@ -39,11 +41,16 @@ export namespace Filesystem {
     return readFile(p)
   }
 
+  export async function readArrayBuffer(p: string): Promise<ArrayBuffer> {
+    const buf = await readFile(p)
+    return buf.buffer.slice(buf.byteOffset, buf.byteOffset + buf.byteLength) as ArrayBuffer
+  }
+
   function isEnoent(e: unknown): e is { code: "ENOENT" } {
     return typeof e === "object" && e !== null && "code" in e && (e as { code: string }).code === "ENOENT"
   }
 
-  export async function write(p: string, content: string | Buffer, mode?: number): Promise<void> {
+  export async function write(p: string, content: string | Buffer | Uint8Array, mode?: number): Promise<void> {
     try {
       if (mode) {
         await writeFile(p, content, { mode })
@@ -68,6 +75,25 @@ export namespace Filesystem {
     return write(p, JSON.stringify(data, null, 2), mode)
   }
 
+  export async function writeStream(
+    p: string,
+    stream: ReadableStream<Uint8Array> | Readable,
+    mode?: number,
+  ): Promise<void> {
+    const dir = dirname(p)
+    if (!existsSync(dir)) {
+      await mkdir(dir, { recursive: true })
+    }
+
+    const nodeStream = stream instanceof ReadableStream ? Readable.fromWeb(stream as any) : stream
+    const writeStream = createWriteStream(p)
+    await pipeline(nodeStream, writeStream)
+
+    if (mode) {
+      await chmod(p, mode)
+    }
+  }
+
   export function mimeType(p: string): string {
     return lookup(p) || "application/octet-stream"
   }

packages/opencode/src/util/log.ts

@@ -1,5 +1,6 @@
 import path from "path"
 import fs from "fs/promises"
+import { createWriteStream } from "fs"
 import { Global } from "../global"
 import z from "zod"
 
@@ -63,13 +64,15 @@ export namespace Log {
       Global.Path.log,
       options.dev ? "dev.log" : new Date().toISOString().split(".")[0].replace(/:/g, "") + ".log",
     )
-    const logfile = Bun.file(logpath)
     await fs.truncate(logpath).catch(() => {})
-    const writer = logfile.writer()
+    const stream = createWriteStream(logpath, { flags: "a" })
     write = async (msg: any) => {
-      const num = writer.write(msg)
+      return new Promise((resolve, reject) => {
-      writer.flush()
+        stream.write(msg, (err) => {
-      return num
+          if (err) reject(err)
+          else resolve(msg.length)
+        })
+      })
     }
   }
 

packages/opencode/test/config/config.test.ts

@@ -7,6 +7,7 @@ import path from "path"
 import fs from "fs/promises"
 import { pathToFileURL } from "url"
 import { Global } from "../../src/global"
+import { Filesystem } from "../../src/util/filesystem"
 
 // Get managed config directory from environment (set in preload.ts)
 const managedConfigDir = process.env.OPENCODE_TEST_MANAGED_CONFIG_DIR!
@@ -17,11 +18,11 @@ afterEach(async () => {
 
 async function writeManagedSettings(settings: object, filename = "opencode.json") {
   await fs.mkdir(managedConfigDir, { recursive: true })
-  await Bun.write(path.join(managedConfigDir, filename), JSON.stringify(settings))
+  await Filesystem.write(path.join(managedConfigDir, filename), JSON.stringify(settings))
 }
 
 async function writeConfig(dir: string, config: object, name = "opencode.json") {
-  await Bun.write(path.join(dir, name), JSON.stringify(config))
+  await Filesystem.write(path.join(dir, name), JSON.stringify(config))
 }
 
 test("loads config with defaults when no files exist", async () => {
@@ -58,7 +59,7 @@ test("loads JSON config file", async () => {
 test("loads JSONC config file", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.jsonc"),
         `{
         // This is a comment
@@ -144,7 +145,7 @@ test("preserves env variables when adding $schema to config", async () => {
     await using tmp = await tmpdir({
       init: async (dir) => {
         // Config without $schema - should trigger auto-add
-        await Bun.write(
+        await Filesystem.write(
           path.join(dir, "opencode.json"),
           JSON.stringify({
             theme: "{env:PRESERVE_VAR}",
@@ -159,7 +160,7 @@ test("preserves env variables when adding $schema to config", async () => {
         expect(config.theme).toBe("secret_value")
 
         // Read the file to verify the env variable was preserved
-        const content = await Bun.file(path.join(tmp.path, "opencode.json")).text()
+        const content = await Filesystem.readText(path.join(tmp.path, "opencode.json"))
         expect(content).toContain("{env:PRESERVE_VAR}")
         expect(content).not.toContain("secret_value")
         expect(content).toContain("$schema")
@@ -177,7 +178,7 @@ test("preserves env variables when adding $schema to config", async () => {
 test("handles file inclusion substitution", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {
-      await Bun.write(path.join(dir, "included.txt"), "test_theme")
+      await Filesystem.write(path.join(dir, "included.txt"), "test_theme")
       await writeConfig(dir, {
         $schema: "https://opencode.ai/config.json",
         theme: "{file:included.txt}",
@@ -196,7 +197,7 @@ test("handles file inclusion substitution", async () => {
 test("handles file inclusion with replacement tokens", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {
-      await Bun.write(path.join(dir, "included.md"), "const out = await Bun.$`echo hi`")
+      await Filesystem.write(path.join(dir, "included.md"), "const out = await Bun.$`echo hi`")
       await writeConfig(dir, {
         $schema: "https://opencode.ai/config.json",
         theme: "{file:included.md}",
@@ -233,7 +234,7 @@ test("validates config schema and throws on invalid fields", async () => {
 test("throws error for invalid JSON", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {
-      await Bun.write(path.join(dir, "opencode.json"), "{ invalid json }")
+      await Filesystem.write(path.join(dir, "opencode.json"), "{ invalid json }")
     },
   })
   await Instance.provide({
@@ -336,7 +337,7 @@ test("handles command configuration", async () => {
 test("migrates autoshare to share field", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -358,7 +359,7 @@ test("migrates autoshare to share field", async () => {
 test("migrates mode field to agent field", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -395,7 +396,7 @@ test("loads config from .opencode directory", async () => {
       const agentDir = path.join(opencodeDir, "agent")
       await fs.mkdir(agentDir, { recursive: true })
 
-      await Bun.write(
+      await Filesystem.write(
         path.join(agentDir, "test.md"),
         `---
 model: test/model
@@ -428,7 +429,7 @@ test("loads agents from .opencode/agents (plural)", async () => {
       const agentsDir = path.join(opencodeDir, "agents")
       await fs.mkdir(path.join(agentsDir, "nested"), { recursive: true })
 
-      await Bun.write(
+      await Filesystem.write(
         path.join(agentsDir, "helper.md"),
         `---
 model: test/model
@@ -437,7 +438,7 @@ mode: subagent
 Helper agent prompt`,
       )
 
-      await Bun.write(
+      await Filesystem.write(
         path.join(agentsDir, "nested", "child.md"),
         `---
 model: test/model
@@ -479,7 +480,7 @@ test("loads commands from .opencode/command (singular)", async () => {
       const commandDir = path.join(opencodeDir, "command")
       await fs.mkdir(path.join(commandDir, "nested"), { recursive: true })
 
-      await Bun.write(
+      await Filesystem.write(
         path.join(commandDir, "hello.md"),
         `---
 description: Test command
@@ -487,7 +488,7 @@ description: Test command
 Hello from singular command`,
       )
 
-      await Bun.write(
+      await Filesystem.write(
         path.join(commandDir, "nested", "child.md"),
         `---
 description: Nested command
@@ -524,7 +525,7 @@ test("loads commands from .opencode/commands (plural)", async () => {
       const commandsDir = path.join(opencodeDir, "commands")
       await fs.mkdir(path.join(commandsDir, "nested"), { recursive: true })
 
-      await Bun.write(
+      await Filesystem.write(
         path.join(commandsDir, "hello.md"),
         `---
 description: Test command
@@ -532,7 +533,7 @@ description: Test command
 Hello from plural commands`,
       )
 
-      await Bun.write(
+      await Filesystem.write(
         path.join(commandsDir, "nested", "child.md"),
         `---
 description: Nested command
@@ -568,7 +569,7 @@ test("updates config and writes to file", async () => {
       const newConfig = { model: "updated/model" }
       await Config.update(newConfig as any)
 
-      const writtenConfig = JSON.parse(await Bun.file(path.join(tmp.path, "config.json")).text())
+      const writtenConfig = await Filesystem.readJson(path.join(tmp.path, "config.json"))
       expect(writtenConfig.model).toBe("updated/model")
     },
   })
@@ -639,8 +640,8 @@ test("installs dependencies in writable OPENCODE_CONFIG_DIR", async () => {
       },
     })
 
-    expect(await Bun.file(path.join(tmp.extra, "package.json")).exists()).toBe(true)
+    expect(await Filesystem.exists(path.join(tmp.extra, "package.json"))).toBe(true)
-    expect(await Bun.file(path.join(tmp.extra, ".gitignore")).exists()).toBe(true)
+    expect(await Filesystem.exists(path.join(tmp.extra, ".gitignore"))).toBe(true)
   } finally {
     if (prev === undefined) delete process.env.OPENCODE_CONFIG_DIR
     else process.env.OPENCODE_CONFIG_DIR = prev
@@ -653,12 +654,12 @@ test("resolves scoped npm plugins in config", async () => {
       const pluginDir = path.join(dir, "node_modules", "@scope", "plugin")
       await fs.mkdir(pluginDir, { recursive: true })
 
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "package.json"),
         JSON.stringify({ name: "config-fixture", version: "1.0.0", type: "module" }, null, 2),
       )
 
-      await Bun.write(
+      await Filesystem.write(
         path.join(pluginDir, "package.json"),
         JSON.stringify(
           {
@@ -672,9 +673,9 @@ test("resolves scoped npm plugins in config", async () => {
         ),
       )
 
-      await Bun.write(path.join(pluginDir, "index.js"), "export default {}\n")
+      await Filesystem.write(path.join(pluginDir, "index.js"), "export default {}\n")
 
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.json"),
         JSON.stringify({ $schema: "https://opencode.ai/config.json", plugin: ["@scope/plugin"] }, null, 2),
       )
@@ -708,7 +709,7 @@ test("merges plugin arrays from global and local configs", async () => {
       await fs.mkdir(opencodeDir, { recursive: true })
 
       // Global config with plugins
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -717,7 +718,7 @@ test("merges plugin arrays from global and local configs", async () => {
       )
 
       // Local .opencode config with different plugins
-      await Bun.write(
+      await Filesystem.write(
         path.join(opencodeDir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -753,7 +754,7 @@ test("does not error when only custom agent is a subagent", async () => {
       const agentDir = path.join(opencodeDir, "agent")
       await fs.mkdir(agentDir, { recursive: true })
 
-      await Bun.write(
+      await Filesystem.write(
         path.join(agentDir, "helper.md"),
         `---
 model: test/model
@@ -784,7 +785,7 @@ test("merges instructions arrays from global and local configs", async () => {
       const opencodeDir = path.join(projectDir, ".opencode")
       await fs.mkdir(opencodeDir, { recursive: true })
 
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -792,7 +793,7 @@ test("merges instructions arrays from global and local configs", async () => {
         }),
       )
 
-      await Bun.write(
+      await Filesystem.write(
         path.join(opencodeDir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -823,7 +824,7 @@ test("deduplicates duplicate instructions from global and local configs", async
       const opencodeDir = path.join(projectDir, ".opencode")
       await fs.mkdir(opencodeDir, { recursive: true })
 
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -831,7 +832,7 @@ test("deduplicates duplicate instructions from global and local configs", async
         }),
       )
 
-      await Bun.write(
+      await Filesystem.write(
         path.join(opencodeDir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -867,7 +868,7 @@ test("deduplicates duplicate plugins from global and local configs", async () =>
       await fs.mkdir(opencodeDir, { recursive: true })
 
       // Global config with plugins
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -876,7 +877,7 @@ test("deduplicates duplicate plugins from global and local configs", async () =>
       )
 
       // Local .opencode config with some overlapping plugins
-      await Bun.write(
+      await Filesystem.write(
         path.join(opencodeDir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -915,7 +916,7 @@ test("deduplicates duplicate plugins from global and local configs", async () =>
 test("migrates legacy tools config to permissions - allow", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -946,7 +947,7 @@ test("migrates legacy tools config to permissions - allow", async () => {
 test("migrates legacy tools config to permissions - deny", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -977,7 +978,7 @@ test("migrates legacy tools config to permissions - deny", async () => {
 test("migrates legacy write tool to edit permission", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -1086,7 +1087,7 @@ test("missing managed settings file is not an error", async () => {
 test("migrates legacy edit tool to edit permission", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -1115,7 +1116,7 @@ test("migrates legacy edit tool to edit permission", async () => {
 test("migrates legacy patch tool to edit permission", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -1144,7 +1145,7 @@ test("migrates legacy patch tool to edit permission", async () => {
 test("migrates legacy multiedit tool to edit permission", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -1173,7 +1174,7 @@ test("migrates legacy multiedit tool to edit permission", async () => {
 test("migrates mixed legacy tools config", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -1208,7 +1209,7 @@ test("migrates mixed legacy tools config", async () => {
 test("merges legacy tools with existing permission config", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -1241,7 +1242,7 @@ test("merges legacy tools with existing permission config", async () => {
 test("permission config preserves key order", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -1289,7 +1290,7 @@ test("project config can override MCP server enabled status", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {
       // Simulates a base config (like from remote .well-known) with disabled MCP
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.jsonc"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -1308,7 +1309,7 @@ test("project config can override MCP server enabled status", async () => {
         }),
       )
       // Project config enables just jira
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -1347,7 +1348,7 @@ test("MCP config deep merges preserving base config properties", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {
       // Base config with full MCP definition
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.jsonc"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -1364,7 +1365,7 @@ test("MCP config deep merges preserving base config properties", async () => {
         }),
       )
       // Override just enables it, should preserve other properties
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -1399,7 +1400,7 @@ test("local .opencode config can override MCP from project config", async () =>
   await using tmp = await tmpdir({
     init: async (dir) => {
       // Project config with disabled MCP
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -1415,7 +1416,7 @@ test("local .opencode config can override MCP from project config", async () =>
       // Local .opencode directory config enables it
       const opencodeDir = path.join(dir, ".opencode")
       await fs.mkdir(opencodeDir, { recursive: true })
-      await Bun.write(
+      await Filesystem.write(
         path.join(opencodeDir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -1483,7 +1484,7 @@ test("project config overrides remote well-known config", async () => {
       git: true,
       init: async (dir) => {
         // Project config enables jira (overriding remote default)
-        await Bun.write(
+        await Filesystem.write(
           path.join(dir, "opencode.json"),
           JSON.stringify({
             $schema: "https://opencode.ai/config.json",
@@ -1576,7 +1577,7 @@ describe("deduplicatePlugins", () => {
         const pluginDir = path.join(opencodeDir, "plugin")
         await fs.mkdir(pluginDir, { recursive: true })
 
-        await Bun.write(
+        await Filesystem.write(
           path.join(dir, "opencode.json"),
           JSON.stringify({
             $schema: "https://opencode.ai/config.json",
@@ -1584,7 +1585,7 @@ describe("deduplicatePlugins", () => {
           }),
         )
 
-        await Bun.write(path.join(pluginDir, "my-plugin.js"), "export default {}")
+        await Filesystem.write(path.join(pluginDir, "my-plugin.js"), "export default {}")
       },
     })
 
@@ -1611,7 +1612,7 @@ describe("OPENCODE_DISABLE_PROJECT_CONFIG", () => {
       await using tmp = await tmpdir({
         init: async (dir) => {
           // Create a project config that would normally be loaded
-          await Bun.write(
+          await Filesystem.write(
             path.join(dir, "opencode.json"),
             JSON.stringify({
               $schema: "https://opencode.ai/config.json",
@@ -1649,7 +1650,7 @@ describe("OPENCODE_DISABLE_PROJECT_CONFIG", () => {
           // Create a .opencode directory with a command
           const opencodeDir = path.join(dir, ".opencode", "command")
           await fs.mkdir(opencodeDir, { recursive: true })
-          await Bun.write(path.join(opencodeDir, "test-cmd.md"), "# Test Command\nThis is a test command.")
+          await Filesystem.write(path.join(opencodeDir, "test-cmd.md"), "# Test Command\nThis is a test command.")
         },
       })
       await Instance.provide({
@@ -1706,7 +1707,7 @@ describe("OPENCODE_DISABLE_PROJECT_CONFIG", () => {
       await using tmp = await tmpdir({
         init: async (dir) => {
           // Create a config with relative instruction path
-          await Bun.write(
+          await Filesystem.write(
             path.join(dir, "opencode.json"),
             JSON.stringify({
               $schema: "https://opencode.ai/config.json",
@@ -1714,7 +1715,7 @@ describe("OPENCODE_DISABLE_PROJECT_CONFIG", () => {
             }),
           )
           // Create the instruction file (should be skipped)
-          await Bun.write(path.join(dir, "CUSTOM.md"), "# Custom Instructions")
+          await Filesystem.write(path.join(dir, "CUSTOM.md"), "# Custom Instructions")
         },
       })
 
@@ -1752,7 +1753,7 @@ describe("OPENCODE_DISABLE_PROJECT_CONFIG", () => {
       await using configDirTmp = await tmpdir({
         init: async (dir) => {
           // Create config in the custom config dir
-          await Bun.write(
+          await Filesystem.write(
             path.join(dir, "opencode.json"),
             JSON.stringify({
               $schema: "https://opencode.ai/config.json",
@@ -1765,7 +1766,7 @@ describe("OPENCODE_DISABLE_PROJECT_CONFIG", () => {
       await using projectTmp = await tmpdir({
         init: async (dir) => {
           // Create config in project (should be ignored)
-          await Bun.write(
+          await Filesystem.write(
             path.join(dir, "opencode.json"),
             JSON.stringify({
               $schema: "https://opencode.ai/config.json",

packages/opencode/test/file/index.test.ts

@@ -3,11 +3,12 @@ import path from "path"
 import fs from "fs/promises"
 import { File } from "../../src/file"
 import { Instance } from "../../src/project/instance"
+import { Filesystem } from "../../src/util/filesystem"
 import { tmpdir } from "../fixture/fixture"
 
-describe("file/index Bun.file patterns", () => {
+describe("file/index Filesystem patterns", () => {
   describe("File.read() - text content", () => {
-    test("reads text file via Bun.file().text()", async () => {
+    test("reads text file via Filesystem.readText()", async () => {
       await using tmp = await tmpdir()
       const filepath = path.join(tmp.path, "test.txt")
       await fs.writeFile(filepath, "Hello World", "utf-8")
@@ -22,7 +23,7 @@ describe("file/index Bun.file patterns", () => {
       })
     })
 
-    test("reads with Bun.file().exists() check", async () => {
+    test("reads with Filesystem.exists() check", async () => {
       await using tmp = await tmpdir()
 
       await Instance.provide({
@@ -81,7 +82,7 @@ describe("file/index Bun.file patterns", () => {
   })
 
   describe("File.read() - binary content", () => {
-    test("reads binary file via Bun.file().arrayBuffer()", async () => {
+    test("reads binary file via Filesystem.readArrayBuffer()", async () => {
       await using tmp = await tmpdir()
       const filepath = path.join(tmp.path, "image.png")
       const binaryContent = Buffer.from([0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a])
@@ -115,8 +116,8 @@ describe("file/index Bun.file patterns", () => {
     })
   })
 
-  describe("File.read() - Bun.file().type", () => {
+  describe("File.read() - Filesystem.mimeType()", () => {
-    test("detects MIME type via Bun.file().type", async () => {
+    test("detects MIME type via Filesystem.mimeType()", async () => {
       await using tmp = await tmpdir()
       const filepath = path.join(tmp.path, "test.json")
       await fs.writeFile(filepath, '{"key": "value"}', "utf-8")
@@ -124,8 +125,7 @@ describe("file/index Bun.file patterns", () => {
       await Instance.provide({
         directory: tmp.path,
         fn: async () => {
-          const bunFile = Bun.file(filepath)
+          expect(Filesystem.mimeType(filepath)).toContain("application/json")
-          expect(bunFile.type).toContain("application/json")
 
           const result = await File.read("test.json")
           expect(result.type).toBe("text")
@@ -149,16 +149,15 @@ describe("file/index Bun.file patterns", () => {
         await Instance.provide({
           directory: tmp.path,
           fn: async () => {
-            const bunFile = Bun.file(filepath)
+            expect(Filesystem.mimeType(filepath)).toContain(mime)
-            expect(bunFile.type).toContain(mime)
           },
         })
       }
     })
   })
 
-  describe("File.list() - Bun.file().exists() and .text()", () => {
+  describe("File.list() - Filesystem.exists() and readText()", () => {
-    test("reads .gitignore via Bun.file().exists() and .text()", async () => {
+    test("reads .gitignore via Filesystem.exists() and readText()", async () => {
       await using tmp = await tmpdir({ git: true })
 
       await Instance.provide({
@@ -168,10 +167,9 @@ describe("file/index Bun.file patterns", () => {
           await fs.writeFile(gitignorePath, "node_modules\ndist\n", "utf-8")
 
           // This is used internally in File.list()
-          const bunFile = Bun.file(gitignorePath)
+          expect(await Filesystem.exists(gitignorePath)).toBe(true)
-          expect(await bunFile.exists()).toBe(true)
 
-          const content = await bunFile.text()
+          const content = await Filesystem.readText(gitignorePath)
           expect(content).toContain("node_modules")
         },
       })
@@ -186,9 +184,8 @@ describe("file/index Bun.file patterns", () => {
           const ignorePath = path.join(tmp.path, ".ignore")
           await fs.writeFile(ignorePath, "*.log\n.env\n", "utf-8")
 
-          const bunFile = Bun.file(ignorePath)
+          expect(await Filesystem.exists(ignorePath)).toBe(true)
-          expect(await bunFile.exists()).toBe(true)
+          expect(await Filesystem.readText(ignorePath)).toContain("*.log")
-          expect(await bunFile.text()).toContain("*.log")
         },
       })
     })
@@ -200,8 +197,7 @@ describe("file/index Bun.file patterns", () => {
         directory: tmp.path,
         fn: async () => {
           const gitignorePath = path.join(tmp.path, ".gitignore")
-          const bunFile = Bun.file(gitignorePath)
+          expect(await Filesystem.exists(gitignorePath)).toBe(false)
-          expect(await bunFile.exists()).toBe(false)
 
           // File.list() should still work
           const nodes = await File.list()
@@ -211,8 +207,8 @@ describe("file/index Bun.file patterns", () => {
     })
   })
 
-  describe("File.changed() - Bun.file().text() for untracked files", () => {
+  describe("File.changed() - Filesystem.readText() for untracked files", () => {
-    test("reads untracked files via Bun.file().text()", async () => {
+    test("reads untracked files via Filesystem.readText()", async () => {
       await using tmp = await tmpdir({ git: true })
 
       await Instance.provide({
@@ -222,8 +218,7 @@ describe("file/index Bun.file patterns", () => {
           await fs.writeFile(untrackedPath, "new content\nwith multiple lines", "utf-8")
 
           // This is how File.changed() reads untracked files
-          const bunFile = Bun.file(untrackedPath)
+          const content = await Filesystem.readText(untrackedPath)
-          const content = await bunFile.text()
           const lines = content.split("\n").length
           expect(lines).toBe(2)
         },
@@ -232,7 +227,7 @@ describe("file/index Bun.file patterns", () => {
   })
 
   describe("Error handling", () => {
-    test("handles errors gracefully in Bun.file().text()", async () => {
+    test("handles errors gracefully in Filesystem.readText()", async () => {
       await using tmp = await tmpdir()
       const filepath = path.join(tmp.path, "readonly.txt")
       await fs.writeFile(filepath, "content", "utf-8")
@@ -240,9 +235,9 @@ describe("file/index Bun.file patterns", () => {
       await Instance.provide({
         directory: tmp.path,
         fn: async () => {
-          const nonExistentFile = Bun.file(path.join(tmp.path, "does-not-exist.txt"))
+          const nonExistentPath = path.join(tmp.path, "does-not-exist.txt")
-          // Bun.file().text() on non-existent file throws
+          // Filesystem.readText() on non-existent file throws
-          await expect(nonExistentFile.text()).rejects.toThrow()
+          await expect(Filesystem.readText(nonExistentPath)).rejects.toThrow()
 
           // But File.read() handles this gracefully
           const result = await File.read("does-not-exist.txt")
@@ -251,14 +246,14 @@ describe("file/index Bun.file patterns", () => {
       })
     })
 
-    test("handles errors in Bun.file().arrayBuffer()", async () => {
+    test("handles errors in Filesystem.readArrayBuffer()", async () => {
       await using tmp = await tmpdir()
 
       await Instance.provide({
         directory: tmp.path,
         fn: async () => {
-          const nonExistentFile = Bun.file(path.join(tmp.path, "does-not-exist.bin"))
+          const nonExistentPath = path.join(tmp.path, "does-not-exist.bin")
-          const buffer = await nonExistentFile.arrayBuffer().catch(() => new ArrayBuffer(0))
+          const buffer = await Filesystem.readArrayBuffer(nonExistentPath).catch(() => new ArrayBuffer(0))
           expect(buffer.byteLength).toBe(0)
         },
       })
@@ -272,7 +267,6 @@ describe("file/index Bun.file patterns", () => {
       await Instance.provide({
         directory: tmp.path,
         fn: async () => {
-          const bunFile = Bun.file(filepath)
           // File.read() handles missing images gracefully
           const result = await File.read("broken.png")
           expect(result.type).toBe("text")

packages/opencode/test/file/time.test.ts

@@ -3,6 +3,7 @@ import path from "path"
 import fs from "fs/promises"
 import { FileTime } from "../../src/file/time"
 import { Instance } from "../../src/project/instance"
+import { Filesystem } from "../../src/util/filesystem"
 import { tmpdir } from "../fixture/fixture"
 
 describe("file/time", () => {
@@ -312,8 +313,8 @@ describe("file/time", () => {
     })
   })
 
-  describe("stat() Bun.file pattern", () => {
+  describe("stat() Filesystem.stat pattern", () => {
-    test("reads file modification time via Bun.file().stat()", async () => {
+    test("reads file modification time via Filesystem.stat()", async () => {
       await using tmp = await tmpdir()
       const filepath = path.join(tmp.path, "file.txt")
       await fs.writeFile(filepath, "content", "utf-8")
@@ -323,9 +324,9 @@ describe("file/time", () => {
         fn: async () => {
           FileTime.read(sessionID, filepath)
 
-          const stats = await Bun.file(filepath).stat()
+          const stats = Filesystem.stat(filepath)
-          expect(stats.mtime).toBeInstanceOf(Date)
+          expect(stats?.mtime).toBeInstanceOf(Date)
-          expect(stats.mtime.getTime()).toBeGreaterThan(0)
+          expect(stats!.mtime.getTime()).toBeGreaterThan(0)
 
           // FileTime.assert uses this stat internally
           await FileTime.assert(sessionID, filepath)
@@ -343,14 +344,14 @@ describe("file/time", () => {
         fn: async () => {
           FileTime.read(sessionID, filepath)
 
-          const originalStat = await Bun.file(filepath).stat()
+          const originalStat = Filesystem.stat(filepath)
 
           // Wait and modify
           await new Promise((resolve) => setTimeout(resolve, 100))
           await fs.writeFile(filepath, "modified", "utf-8")
 
-          const newStat = await Bun.file(filepath).stat()
+          const newStat = Filesystem.stat(filepath)
-          expect(newStat.mtime.getTime()).toBeGreaterThan(originalStat.mtime.getTime())
+          expect(newStat!.mtime.getTime()).toBeGreaterThan(originalStat!.mtime.getTime())
 
           await expect(FileTime.assert(sessionID, filepath)).rejects.toThrow()
         },

packages/opencode/test/project/project.test.ts

@@ -4,6 +4,7 @@ import { Log } from "../../src/util/log"
 import { $ } from "bun"
 import path from "path"
 import { tmpdir } from "../fixture/fixture"
+import { Filesystem } from "../../src/util/filesystem"
 import { GlobalBus } from "../../src/bus/global"
 
 Log.init({ print: false })
@@ -78,7 +79,7 @@ describe("Project.fromDirectory", () => {
     expect(project.worktree).toBe(tmp.path)
 
     const opencodeFile = path.join(tmp.path, ".git", "opencode")
-    const fileExists = await Bun.file(opencodeFile).exists()
+    const fileExists = await Filesystem.exists(opencodeFile)
     expect(fileExists).toBe(false)
   })
 
@@ -94,7 +95,7 @@ describe("Project.fromDirectory", () => {
     expect(project.worktree).toBe(tmp.path)
 
     const opencodeFile = path.join(tmp.path, ".git", "opencode")
-    const fileExists = await Bun.file(opencodeFile).exists()
+    const fileExists = await Filesystem.exists(opencodeFile)
     expect(fileExists).toBe(true)
   })
 

packages/opencode/test/project/worktree-remove.test.ts

@@ -4,6 +4,7 @@ import fs from "fs/promises"
 import path from "path"
 import { Instance } from "../../src/project/instance"
 import { Worktree } from "../../src/worktree"
+import { Filesystem } from "../../src/util/filesystem"
 import { tmpdir } from "../fixture/fixture"
 
 describe("Worktree.remove", () => {
@@ -53,7 +54,7 @@ describe("Worktree.remove", () => {
     })()
 
     expect(ok).toBe(true)
-    expect(await Bun.file(dir).exists()).toBe(false)
+    expect(await Filesystem.exists(dir)).toBe(false)
 
     const list = await $`git worktree list --porcelain`.cwd(root).quiet().text()
     expect(list).not.toContain(`worktree ${dir}`)

packages/opencode/test/provider/amazon-bedrock.test.ts

@@ -7,11 +7,12 @@ import { Instance } from "../../src/project/instance"
 import { Provider } from "../../src/provider/provider"
 import { Env } from "../../src/env"
 import { Global } from "../../src/global"
+import { Filesystem } from "../../src/util/filesystem"
 
 test("Bedrock: config region takes precedence over AWS_REGION env var", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -43,7 +44,7 @@ test("Bedrock: config region takes precedence over AWS_REGION env var", async ()
 test("Bedrock: falls back to AWS_REGION env var when no config region", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -68,7 +69,7 @@ test("Bedrock: falls back to AWS_REGION env var when no config region", async ()
 test("Bedrock: loads when bearer token from auth.json is present", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -89,14 +90,14 @@ test("Bedrock: loads when bearer token from auth.json is present", async () => {
   // Save original auth.json if it exists
   let originalAuth: string | undefined
   try {
-    originalAuth = await Bun.file(authPath).text()
+    originalAuth = await Filesystem.readText(authPath)
   } catch {
     // File doesn't exist, that's fine
   }
 
   try {
     // Write test auth.json
-    await Bun.write(
+    await Filesystem.write(
       authPath,
       JSON.stringify({
         "amazon-bedrock": {
@@ -122,7 +123,7 @@ test("Bedrock: loads when bearer token from auth.json is present", async () => {
   } finally {
     // Restore original or delete
     if (originalAuth !== undefined) {
-      await Bun.write(authPath, originalAuth)
+      await Filesystem.write(authPath, originalAuth)
     } else {
       try {
         await unlink(authPath)
@@ -136,7 +137,7 @@ test("Bedrock: loads when bearer token from auth.json is present", async () => {
 test("Bedrock: config profile takes precedence over AWS_PROFILE env var", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -169,7 +170,7 @@ test("Bedrock: config profile takes precedence over AWS_PROFILE env var", async
 test("Bedrock: includes custom endpoint in options when specified", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -202,7 +203,7 @@ test("Bedrock: includes custom endpoint in options when specified", async () =>
 test("Bedrock: autoloads when AWS_WEB_IDENTITY_TOKEN_FILE is present", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -240,7 +241,7 @@ test("Bedrock: autoloads when AWS_WEB_IDENTITY_TOKEN_FILE is present", async ()
 test("Bedrock: model with us. prefix should not be double-prefixed", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -277,7 +278,7 @@ test("Bedrock: model with us. prefix should not be double-prefixed", async () =>
 test("Bedrock: model with global. prefix should not be prefixed", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -313,7 +314,7 @@ test("Bedrock: model with global. prefix should not be prefixed", async () => {
 test("Bedrock: model with eu. prefix should not be double-prefixed", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",
@@ -349,7 +350,7 @@ test("Bedrock: model with eu. prefix should not be double-prefixed", async () =>
 test("Bedrock: model without prefix in US region should get us. prefix added", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {
-      await Bun.write(
+      await Filesystem.write(
         path.join(dir, "opencode.json"),
         JSON.stringify({
           $schema: "https://opencode.ai/config.json",

packages/opencode/test/session/llm.test.ts

@@ -7,6 +7,7 @@ import { Instance } from "../../src/project/instance"
 import { Provider } from "../../src/provider/provider"
 import { ProviderTransform } from "../../src/provider/transform"
 import { ModelsDev } from "../../src/provider/models"
+import { Filesystem } from "../../src/util/filesystem"
 import { tmpdir } from "../fixture/fixture"
 import type { Agent } from "../../src/agent/agent"
 import type { MessageV2 } from "../../src/session/message-v2"
@@ -185,7 +186,7 @@ function createChatStream(text: string) {
 
 async function loadFixture(providerID: string, modelID: string) {
   const fixturePath = path.join(import.meta.dir, "../tool/fixtures/models-api.json")
-  const data = (await Bun.file(fixturePath).json()) as Record<string, ModelsDev.Provider>
+  const data = await Filesystem.readJson<Record<string, ModelsDev.Provider>>(fixturePath)
   const provider = data[providerID]
   if (!provider) {
     throw new Error(`Missing provider in fixture: ${providerID}`)

packages/opencode/test/skill/discovery.test.ts

@@ -1,5 +1,6 @@
 import { describe, test, expect } from "bun:test"
 import { Discovery } from "../../src/skill/discovery"
+import { Filesystem } from "../../src/util/filesystem"
 import path from "path"
 
 const CLOUDFLARE_SKILLS_URL = "https://developers.cloudflare.com/.well-known/skills/"
@@ -11,7 +12,7 @@ describe("Discovery.pull", () => {
     for (const dir of dirs) {
       expect(dir).toStartWith(Discovery.dir())
       const md = path.join(dir, "SKILL.md")
-      expect(await Bun.file(md).exists()).toBe(true)
+      expect(await Filesystem.exists(md)).toBe(true)
     }
   }, 30_000)
 
@@ -20,7 +21,7 @@ describe("Discovery.pull", () => {
     expect(dirs.length).toBeGreaterThan(0)
     for (const dir of dirs) {
       const md = path.join(dir, "SKILL.md")
-      expect(await Bun.file(md).exists()).toBe(true)
+      expect(await Filesystem.exists(md)).toBe(true)
     }
   }, 30_000)
 
@@ -40,7 +41,7 @@ describe("Discovery.pull", () => {
     const agentsSdk = dirs.find((d) => d.endsWith("/agents-sdk"))
     if (agentsSdk) {
       const refs = path.join(agentsSdk, "references")
-      expect(await Bun.file(path.join(agentsSdk, "SKILL.md")).exists()).toBe(true)
+      expect(await Filesystem.exists(path.join(agentsSdk, "SKILL.md"))).toBe(true)
       // agents-sdk has reference files per the index
       const refDir = await Array.fromAsync(new Bun.Glob("**/*.md").scan({ cwd: refs, onlyFiles: true }))
       expect(refDir.length).toBeGreaterThan(0)

packages/opencode/test/snapshot/snapshot.test.ts

@@ -1,7 +1,9 @@
 import { test, expect } from "bun:test"
 import { $ } from "bun"
+import fs from "fs/promises"
 import { Snapshot } from "../../src/snapshot"
 import { Instance } from "../../src/project/instance"
+import { Filesystem } from "../../src/util/filesystem"
 import { tmpdir } from "../fixture/fixture"
 
 async function bootstrap() {
@@ -11,8 +13,8 @@ async function bootstrap() {
       const unique = Math.random().toString(36).slice(2)
       const aContent = `A${unique}`
       const bContent = `B${unique}`
-      await Bun.write(`${dir}/a.txt`, aContent)
+      await Filesystem.write(`${dir}/a.txt`, aContent)
-      await Bun.write(`${dir}/b.txt`, bContent)
+      await Filesystem.write(`${dir}/b.txt`, bContent)
       await $`git add .`.cwd(dir).quiet()
       await $`git commit --no-gpg-sign -m init`.cwd(dir).quiet()
       return {
@@ -46,11 +48,16 @@ test("revert should remove new files", async () => {
       const before = await Snapshot.track()
       expect(before).toBeTruthy()
 
-      await Bun.write(`${tmp.path}/new.txt`, "NEW")
+      await Filesystem.write(`${tmp.path}/new.txt`, "NEW")
 
       await Snapshot.revert([await Snapshot.patch(before!)])
 
-      expect(await Bun.file(`${tmp.path}/new.txt`).exists()).toBe(false)
+      expect(
+        await fs
+          .access(`${tmp.path}/new.txt`)
+          .then(() => true)
+          .catch(() => false),
+      ).toBe(false)
     },
   })
 })
@@ -64,11 +71,16 @@ test("revert in subdirectory", async () => {
       expect(before).toBeTruthy()
 
       await $`mkdir -p ${tmp.path}/sub`.quiet()
-      await Bun.write(`${tmp.path}/sub/file.txt`, "SUB")
+      await Filesystem.write(`${tmp.path}/sub/file.txt`, "SUB")
 
       await Snapshot.revert([await Snapshot.patch(before!)])
 
-      expect(await Bun.file(`${tmp.path}/sub/file.txt`).exists()).toBe(false)
+      expect(
+        await fs
+          .access(`${tmp.path}/sub/file.txt`)
+          .then(() => true)
+          .catch(() => false),
+      ).toBe(false)
       // Note: revert currently only removes files, not directories
       // The empty subdirectory will remain
     },
@@ -84,18 +96,23 @@ test("multiple file operations", async () => {
       expect(before).toBeTruthy()
 
       await $`rm ${tmp.path}/a.txt`.quiet()
-      await Bun.write(`${tmp.path}/c.txt`, "C")
+      await Filesystem.write(`${tmp.path}/c.txt`, "C")
       await $`mkdir -p ${tmp.path}/dir`.quiet()
-      await Bun.write(`${tmp.path}/dir/d.txt`, "D")
+      await Filesystem.write(`${tmp.path}/dir/d.txt`, "D")
-      await Bun.write(`${tmp.path}/b.txt`, "MODIFIED")
+      await Filesystem.write(`${tmp.path}/b.txt`, "MODIFIED")
 
       await Snapshot.revert([await Snapshot.patch(before!)])
 
-      expect(await Bun.file(`${tmp.path}/a.txt`).text()).toBe(tmp.extra.aContent)
+      expect(await fs.readFile(`${tmp.path}/a.txt`, "utf-8")).toBe(tmp.extra.aContent)
-      expect(await Bun.file(`${tmp.path}/c.txt`).exists()).toBe(false)
+      expect(
+        await fs
+          .access(`${tmp.path}/c.txt`)
+          .then(() => true)
+          .catch(() => false),
+      ).toBe(false)
       // Note: revert currently only removes files, not directories
       // The empty directory will remain
-      expect(await Bun.file(`${tmp.path}/b.txt`).text()).toBe(tmp.extra.bContent)
+      expect(await fs.readFile(`${tmp.path}/b.txt`, "utf-8")).toBe(tmp.extra.bContent)
     },
   })
 })
@@ -123,13 +140,18 @@ test("binary file handling", async () => {
       const before = await Snapshot.track()
       expect(before).toBeTruthy()
 
-      await Bun.write(`${tmp.path}/image.png`, new Uint8Array([0x89, 0x50, 0x4e, 0x47]))
+      await Filesystem.write(`${tmp.path}/image.png`, new Uint8Array([0x89, 0x50, 0x4e, 0x47]))
 
       const patch = await Snapshot.patch(before!)
       expect(patch.files).toContain(`${tmp.path}/image.png`)
 
       await Snapshot.revert([patch])
-      expect(await Bun.file(`${tmp.path}/image.png`).exists()).toBe(false)
+      expect(
+        await fs
+          .access(`${tmp.path}/image.png`)
+          .then(() => true)
+          .catch(() => false),
+      ).toBe(false)
     },
   })
 })
@@ -157,7 +179,7 @@ test("large file handling", async () => {
       const before = await Snapshot.track()
       expect(before).toBeTruthy()
 
-      await Bun.write(`${tmp.path}/large.txt`, "x".repeat(1024 * 1024))
+      await Filesystem.write(`${tmp.path}/large.txt`, "x".repeat(1024 * 1024))
 
       expect((await Snapshot.patch(before!)).files).toContain(`${tmp.path}/large.txt`)
     },
@@ -173,11 +195,16 @@ test("nested directory revert", async () => {
       expect(before).toBeTruthy()
 
       await $`mkdir -p ${tmp.path}/level1/level2/level3`.quiet()
-      await Bun.write(`${tmp.path}/level1/level2/level3/deep.txt`, "DEEP")
+      await Filesystem.write(`${tmp.path}/level1/level2/level3/deep.txt`, "DEEP")
 
       await Snapshot.revert([await Snapshot.patch(before!)])
 
-      expect(await Bun.file(`${tmp.path}/level1/level2/level3/deep.txt`).exists()).toBe(false)
+      expect(
+        await fs
+          .access(`${tmp.path}/level1/level2/level3/deep.txt`)
+          .then(() => true)
+          .catch(() => false),
+      ).toBe(false)
     },
   })
 })
@@ -190,9 +217,9 @@ test("special characters in filenames", async () => {
       const before = await Snapshot.track()
       expect(before).toBeTruthy()
 
-      await Bun.write(`${tmp.path}/file with spaces.txt`, "SPACES")
+      await Filesystem.write(`${tmp.path}/file with spaces.txt`, "SPACES")
-      await Bun.write(`${tmp.path}/file-with-dashes.txt`, "DASHES")
+      await Filesystem.write(`${tmp.path}/file-with-dashes.txt`, "DASHES")
-      await Bun.write(`${tmp.path}/file_with_underscores.txt`, "UNDERSCORES")
+      await Filesystem.write(`${tmp.path}/file_with_underscores.txt`, "UNDERSCORES")
 
       const files = (await Snapshot.patch(before!)).files
       expect(files).toContain(`${tmp.path}/file with spaces.txt`)
@@ -225,7 +252,7 @@ test("patch with invalid hash", async () => {
       expect(before).toBeTruthy()
 
       // Create a change
-      await Bun.write(`${tmp.path}/test.txt`, "TEST")
+      await Filesystem.write(`${tmp.path}/test.txt`, "TEST")
 
       // Try to patch with invalid hash - should handle gracefully
       const patch = await Snapshot.patch("invalid-hash-12345")
@@ -273,7 +300,7 @@ test("unicode filenames", async () => {
       ]
 
       for (const file of unicodeFiles) {
-        await Bun.write(file.path, file.content)
+        await Filesystem.write(file.path, file.content)
       }
 
       const patch = await Snapshot.patch(before!)
@@ -286,7 +313,12 @@ test("unicode filenames", async () => {
       await Snapshot.revert([patch])
 
       for (const file of unicodeFiles) {
-        expect(await Bun.file(file.path).exists()).toBe(false)
+        expect(
+          await fs
+            .access(file.path)
+            .then(() => true)
+            .catch(() => false),
+        ).toBe(false)
       }
     },
   })
@@ -300,14 +332,14 @@ test.skip("unicode filenames modification and restore", async () => {
       const chineseFile = `${tmp.path}/文件.txt`
       const cyrillicFile = `${tmp.path}/файл.txt`
 
-      await Bun.write(chineseFile, "original chinese")
+      await Filesystem.write(chineseFile, "original chinese")
-      await Bun.write(cyrillicFile, "original cyrillic")
+      await Filesystem.write(cyrillicFile, "original cyrillic")
 
       const before = await Snapshot.track()
       expect(before).toBeTruthy()
 
-      await Bun.write(chineseFile, "modified chinese")
+      await Filesystem.write(chineseFile, "modified chinese")
-      await Bun.write(cyrillicFile, "modified cyrillic")
+      await Filesystem.write(cyrillicFile, "modified cyrillic")
 
       const patch = await Snapshot.patch(before!)
       expect(patch.files).toContain(chineseFile)
@@ -315,8 +347,8 @@ test.skip("unicode filenames modification and restore", async () => {
 
       await Snapshot.revert([patch])
 
-      expect(await Bun.file(chineseFile).text()).toBe("original chinese")
+      expect(await fs.readFile(chineseFile, "utf-8")).toBe("original chinese")
-      expect(await Bun.file(cyrillicFile).text()).toBe("original cyrillic")
+      expect(await fs.readFile(cyrillicFile, "utf-8")).toBe("original cyrillic")
     },
   })
 })
@@ -331,13 +363,18 @@ test("unicode filenames in subdirectories", async () => {
 
       await $`mkdir -p "${tmp.path}/目录/подкаталог"`.quiet()
       const deepFile = `${tmp.path}/目录/подкаталог/文件.txt`
-      await Bun.write(deepFile, "deep unicode content")
+      await Filesystem.write(deepFile, "deep unicode content")
 
       const patch = await Snapshot.patch(before!)
       expect(patch.files).toContain(deepFile)
 
       await Snapshot.revert([patch])
-      expect(await Bun.file(deepFile).exists()).toBe(false)
+      expect(
+        await fs
+          .access(deepFile)
+          .then(() => true)
+          .catch(() => false),
+      ).toBe(false)
     },
   })
 })
@@ -353,13 +390,18 @@ test("very long filenames", async () => {
       const longName = "a".repeat(200) + ".txt"
       const longFile = `${tmp.path}/${longName}`
 
-      await Bun.write(longFile, "long filename content")
+      await Filesystem.write(longFile, "long filename content")
 
       const patch = await Snapshot.patch(before!)
       expect(patch.files).toContain(longFile)
 
       await Snapshot.revert([patch])
-      expect(await Bun.file(longFile).exists()).toBe(false)
+      expect(
+        await fs
+          .access(longFile)
+          .then(() => true)
+          .catch(() => false),
+      ).toBe(false)
     },
   })
 })
@@ -372,9 +414,9 @@ test("hidden files", async () => {
       const before = await Snapshot.track()
       expect(before).toBeTruthy()
 
-      await Bun.write(`${tmp.path}/.hidden`, "hidden content")
+      await Filesystem.write(`${tmp.path}/.hidden`, "hidden content")
-      await Bun.write(`${tmp.path}/.gitignore`, "*.log")
+      await Filesystem.write(`${tmp.path}/.gitignore`, "*.log")
-      await Bun.write(`${tmp.path}/.config`, "config content")
+      await Filesystem.write(`${tmp.path}/.config`, "config content")
 
       const patch = await Snapshot.patch(before!)
       expect(patch.files).toContain(`${tmp.path}/.hidden`)
@@ -393,7 +435,7 @@ test("nested symlinks", async () => {
       expect(before).toBeTruthy()
 
       await $`mkdir -p ${tmp.path}/sub/dir`.quiet()
-      await Bun.write(`${tmp.path}/sub/dir/target.txt`, "target content")
+      await Filesystem.write(`${tmp.path}/sub/dir/target.txt`, "target content")
       await $`ln -s ${tmp.path}/sub/dir/target.txt ${tmp.path}/sub/dir/link.txt`.quiet()
       await $`ln -s ${tmp.path}/sub ${tmp.path}/sub-link`.quiet()
 
@@ -450,9 +492,9 @@ test("gitignore changes", async () => {
       const before = await Snapshot.track()
       expect(before).toBeTruthy()
 
-      await Bun.write(`${tmp.path}/.gitignore`, "*.ignored")
+      await Filesystem.write(`${tmp.path}/.gitignore`, "*.ignored")
-      await Bun.write(`${tmp.path}/test.ignored`, "ignored content")
+      await Filesystem.write(`${tmp.path}/test.ignored`, "ignored content")
-      await Bun.write(`${tmp.path}/normal.txt`, "normal content")
+      await Filesystem.write(`${tmp.path}/normal.txt`, "normal content")
 
       const patch = await Snapshot.patch(before!)
 
@@ -477,7 +519,7 @@ test("concurrent file operations during patch", async () => {
       // Start creating files
       const createPromise = (async () => {
         for (let i = 0; i < 10; i++) {
-          await Bun.write(`${tmp.path}/concurrent${i}.txt`, `concurrent${i}`)
+          await Filesystem.write(`${tmp.path}/concurrent${i}.txt`, `concurrent${i}`)
           // Small delay to simulate concurrent operations
           await new Promise((resolve) => setTimeout(resolve, 1))
         }
@@ -504,7 +546,7 @@ test("snapshot state isolation between projects", async () => {
     directory: tmp1.path,
     fn: async () => {
       const before1 = await Snapshot.track()
-      await Bun.write(`${tmp1.path}/project1.txt`, "project1 content")
+      await Filesystem.write(`${tmp1.path}/project1.txt`, "project1 content")
       const patch1 = await Snapshot.patch(before1!)
       expect(patch1.files).toContain(`${tmp1.path}/project1.txt`)
     },
@@ -514,7 +556,7 @@ test("snapshot state isolation between projects", async () => {
     directory: tmp2.path,
     fn: async () => {
       const before2 = await Snapshot.track()
-      await Bun.write(`${tmp2.path}/project2.txt`, "project2 content")
+      await Filesystem.write(`${tmp2.path}/project2.txt`, "project2 content")
       const patch2 = await Snapshot.patch(before2!)
       expect(patch2.files).toContain(`${tmp2.path}/project2.txt`)
 
@@ -544,7 +586,7 @@ test("patch detects changes in secondary worktree", async () => {
         expect(before).toBeTruthy()
 
         const worktreeFile = `${worktreePath}/worktree.txt`
-        await Bun.write(worktreeFile, "worktree content")
+        await Filesystem.write(worktreeFile, "worktree content")
 
         const patch = await Snapshot.patch(before!)
         expect(patch.files).toContain(worktreeFile)
@@ -569,7 +611,7 @@ test("revert only removes files in invoking worktree", async () => {
       },
     })
     const primaryFile = `${tmp.path}/worktree.txt`
-    await Bun.write(primaryFile, "primary content")
+    await Filesystem.write(primaryFile, "primary content")
 
     await Instance.provide({
       directory: worktreePath,
@@ -578,16 +620,21 @@ test("revert only removes files in invoking worktree", async () => {
         expect(before).toBeTruthy()
 
         const worktreeFile = `${worktreePath}/worktree.txt`
-        await Bun.write(worktreeFile, "worktree content")
+        await Filesystem.write(worktreeFile, "worktree content")
 
         const patch = await Snapshot.patch(before!)
         await Snapshot.revert([patch])
 
-        expect(await Bun.file(worktreeFile).exists()).toBe(false)
+        expect(
+          await fs
+            .access(worktreeFile)
+            .then(() => true)
+            .catch(() => false),
+        ).toBe(false)
       },
     })
 
-    expect(await Bun.file(primaryFile).text()).toBe("primary content")
+    expect(await fs.readFile(primaryFile, "utf-8")).toBe("primary content")
   } finally {
     await $`git worktree remove --force ${worktreePath}`.cwd(tmp.path).quiet().nothrow()
     await $`rm -rf ${worktreePath}`.quiet()
@@ -614,10 +661,10 @@ test("diff reports worktree-only/shared edits and ignores primary-only", async (
         const before = await Snapshot.track()
         expect(before).toBeTruthy()
 
-        await Bun.write(`${worktreePath}/worktree-only.txt`, "worktree diff content")
+        await Filesystem.write(`${worktreePath}/worktree-only.txt`, "worktree diff content")
-        await Bun.write(`${worktreePath}/shared.txt`, "worktree edit")
+        await Filesystem.write(`${worktreePath}/shared.txt`, "worktree edit")
-        await Bun.write(`${tmp.path}/shared.txt`, "primary edit")
+        await Filesystem.write(`${tmp.path}/shared.txt`, "primary edit")
-        await Bun.write(`${tmp.path}/primary-only.txt`, "primary change")
+        await Filesystem.write(`${tmp.path}/primary-only.txt`, "primary change")
 
         const diff = await Snapshot.diff(before!)
         expect(diff).toContain("worktree-only.txt")
@@ -662,8 +709,8 @@ test("diff function with various changes", async () => {
 
       // Make various changes
       await $`rm ${tmp.path}/a.txt`.quiet()
-      await Bun.write(`${tmp.path}/new.txt`, "new content")
+      await Filesystem.write(`${tmp.path}/new.txt`, "new content")
-      await Bun.write(`${tmp.path}/b.txt`, "modified content")
+      await Filesystem.write(`${tmp.path}/b.txt`, "modified content")
 
       const diff = await Snapshot.diff(before!)
       expect(diff).toContain("a.txt")
@@ -683,16 +730,26 @@ test("restore function", async () => {
 
       // Make changes
       await $`rm ${tmp.path}/a.txt`.quiet()
-      await Bun.write(`${tmp.path}/new.txt`, "new content")
+      await Filesystem.write(`${tmp.path}/new.txt`, "new content")
-      await Bun.write(`${tmp.path}/b.txt`, "modified")
+      await Filesystem.write(`${tmp.path}/b.txt`, "modified")
 
       // Restore to original state
       await Snapshot.restore(before!)
 
-      expect(await Bun.file(`${tmp.path}/a.txt`).exists()).toBe(true)
+      expect(
-      expect(await Bun.file(`${tmp.path}/a.txt`).text()).toBe(tmp.extra.aContent)
+        await fs
-      expect(await Bun.file(`${tmp.path}/new.txt`).exists()).toBe(true) // New files should remain
+          .access(`${tmp.path}/a.txt`)
-      expect(await Bun.file(`${tmp.path}/b.txt`).text()).toBe(tmp.extra.bContent)
+          .then(() => true)
+          .catch(() => false),
+      ).toBe(true)
+      expect(await fs.readFile(`${tmp.path}/a.txt`, "utf-8")).toBe(tmp.extra.aContent)
+      expect(
+        await fs
+          .access(`${tmp.path}/new.txt`)
+          .then(() => true)
+          .catch(() => false),
+      ).toBe(true) // New files should remain
+      expect(await fs.readFile(`${tmp.path}/b.txt`, "utf-8")).toBe(tmp.extra.bContent)
     },
   })
 })
@@ -710,14 +767,19 @@ test("revert should not delete files that existed but were deleted in snapshot",
       const snapshot2 = await Snapshot.track()
       expect(snapshot2).toBeTruthy()
 
-      await Bun.write(`${tmp.path}/a.txt`, "recreated content")
+      await Filesystem.write(`${tmp.path}/a.txt`, "recreated content")
 
       const patch = await Snapshot.patch(snapshot2!)
       expect(patch.files).toContain(`${tmp.path}/a.txt`)
 
       await Snapshot.revert([patch])
 
-      expect(await Bun.file(`${tmp.path}/a.txt`).exists()).toBe(false)
+      expect(
+        await fs
+          .access(`${tmp.path}/a.txt`)
+          .then(() => true)
+          .catch(() => false),
+      ).toBe(false)
     },
   })
 })
@@ -727,14 +789,14 @@ test("revert preserves file that existed in snapshot when deleted then recreated
   await Instance.provide({
     directory: tmp.path,
     fn: async () => {
-      await Bun.write(`${tmp.path}/existing.txt`, "original content")
+      await Filesystem.write(`${tmp.path}/existing.txt`, "original content")
 
       const snapshot = await Snapshot.track()
       expect(snapshot).toBeTruthy()
 
       await $`rm ${tmp.path}/existing.txt`.quiet()
-      await Bun.write(`${tmp.path}/existing.txt`, "recreated")
+      await Filesystem.write(`${tmp.path}/existing.txt`, "recreated")
-      await Bun.write(`${tmp.path}/newfile.txt`, "new")
+      await Filesystem.write(`${tmp.path}/newfile.txt`, "new")
 
       const patch = await Snapshot.patch(snapshot!)
       expect(patch.files).toContain(`${tmp.path}/existing.txt`)
@@ -742,9 +804,19 @@ test("revert preserves file that existed in snapshot when deleted then recreated
 
       await Snapshot.revert([patch])
 
-      expect(await Bun.file(`${tmp.path}/newfile.txt`).exists()).toBe(false)
+      expect(
-      expect(await Bun.file(`${tmp.path}/existing.txt`).exists()).toBe(true)
+        await fs
-      expect(await Bun.file(`${tmp.path}/existing.txt`).text()).toBe("original content")
+          .access(`${tmp.path}/newfile.txt`)
+          .then(() => true)
+          .catch(() => false),
+      ).toBe(false)
+      expect(
+        await fs
+          .access(`${tmp.path}/existing.txt`)
+          .then(() => true)
+          .catch(() => false),
+      ).toBe(true)
+      expect(await fs.readFile(`${tmp.path}/existing.txt`, "utf-8")).toBe("original content")
     },
   })
 })
@@ -754,17 +826,17 @@ test("diffFull sets status based on git change type", async () => {
   await Instance.provide({
     directory: tmp.path,
     fn: async () => {
-      await Bun.write(`${tmp.path}/grow.txt`, "one\n")
+      await Filesystem.write(`${tmp.path}/grow.txt`, "one\n")
-      await Bun.write(`${tmp.path}/trim.txt`, "line1\nline2\n")
+      await Filesystem.write(`${tmp.path}/trim.txt`, "line1\nline2\n")
-      await Bun.write(`${tmp.path}/delete.txt`, "gone")
+      await Filesystem.write(`${tmp.path}/delete.txt`, "gone")
 
       const before = await Snapshot.track()
       expect(before).toBeTruthy()
 
-      await Bun.write(`${tmp.path}/grow.txt`, "one\ntwo\n")
+      await Filesystem.write(`${tmp.path}/grow.txt`, "one\ntwo\n")
-      await Bun.write(`${tmp.path}/trim.txt`, "line1\n")
+      await Filesystem.write(`${tmp.path}/trim.txt`, "line1\n")
       await $`rm ${tmp.path}/delete.txt`.quiet()
-      await Bun.write(`${tmp.path}/added.txt`, "new")
+      await Filesystem.write(`${tmp.path}/added.txt`, "new")
 
       const after = await Snapshot.track()
       expect(after).toBeTruthy()
@@ -803,7 +875,7 @@ test("diffFull with new file additions", async () => {
       const before = await Snapshot.track()
       expect(before).toBeTruthy()
 
-      await Bun.write(`${tmp.path}/new.txt`, "new content")
+      await Filesystem.write(`${tmp.path}/new.txt`, "new content")
 
       const after = await Snapshot.track()
       expect(after).toBeTruthy()
@@ -829,7 +901,7 @@ test("diffFull with file modifications", async () => {
       const before = await Snapshot.track()
       expect(before).toBeTruthy()
 
-      await Bun.write(`${tmp.path}/b.txt`, "modified content")
+      await Filesystem.write(`${tmp.path}/b.txt`, "modified content")
 
       const after = await Snapshot.track()
       expect(after).toBeTruthy()
@@ -881,7 +953,7 @@ test("diffFull with multiple line additions", async () => {
       const before = await Snapshot.track()
       expect(before).toBeTruthy()
 
-      await Bun.write(`${tmp.path}/multi.txt`, "line1\nline2\nline3")
+      await Filesystem.write(`${tmp.path}/multi.txt`, "line1\nline2\nline3")
 
       const after = await Snapshot.track()
       expect(after).toBeTruthy()
@@ -907,7 +979,7 @@ test("diffFull with addition and deletion", async () => {
       const before = await Snapshot.track()
       expect(before).toBeTruthy()
 
-      await Bun.write(`${tmp.path}/added.txt`, "added content")
+      await Filesystem.write(`${tmp.path}/added.txt`, "added content")
       await $`rm ${tmp.path}/a.txt`.quiet()
 
       const after = await Snapshot.track()
@@ -941,8 +1013,8 @@ test("diffFull with multiple additions and deletions", async () => {
       const before = await Snapshot.track()
       expect(before).toBeTruthy()
 
-      await Bun.write(`${tmp.path}/multi1.txt`, "line1\nline2\nline3")
+      await Filesystem.write(`${tmp.path}/multi1.txt`, "line1\nline2\nline3")
-      await Bun.write(`${tmp.path}/multi2.txt`, "single line")
+      await Filesystem.write(`${tmp.path}/multi2.txt`, "single line")
       await $`rm ${tmp.path}/a.txt`.quiet()
       await $`rm ${tmp.path}/b.txt`.quiet()
 
@@ -1000,7 +1072,7 @@ test("diffFull with binary file changes", async () => {
       const before = await Snapshot.track()
       expect(before).toBeTruthy()
 
-      await Bun.write(`${tmp.path}/binary.bin`, new Uint8Array([0x00, 0x01, 0x02, 0x03]))
+      await Filesystem.write(`${tmp.path}/binary.bin`, new Uint8Array([0x00, 0x01, 0x02, 0x03]))
 
       const after = await Snapshot.track()
       expect(after).toBeTruthy()
@@ -1020,11 +1092,11 @@ test("diffFull with whitespace changes", async () => {
   await Instance.provide({
     directory: tmp.path,
     fn: async () => {
-      await Bun.write(`${tmp.path}/whitespace.txt`, "line1\nline2")
+      await Filesystem.write(`${tmp.path}/whitespace.txt`, "line1\nline2")
       const before = await Snapshot.track()
       expect(before).toBeTruthy()
 
-      await Bun.write(`${tmp.path}/whitespace.txt`, "line1\n\nline2\n")
+      await Filesystem.write(`${tmp.path}/whitespace.txt`, "line1\n\nline2\n")
 
       const after = await Snapshot.track()
       expect(after).toBeTruthy()

packages/opencode/test/tool/bash.test.ts

@@ -2,6 +2,7 @@ import { describe, expect, test } from "bun:test"
 import path from "path"
 import { BashTool } from "../../src/tool/bash"
 import { Instance } from "../../src/project/instance"
+import { Filesystem } from "../../src/util/filesystem"
 import { tmpdir } from "../fixture/fixture"
 import type { PermissionNext } from "../../src/permission/next"
 import { Truncate } from "../../src/tool/truncation"
@@ -388,7 +389,7 @@ describe("tool.bash truncation", () => {
         const filepath = (result.metadata as any).outputPath
         expect(filepath).toBeTruthy()
 
-        const saved = await Bun.file(filepath).text()
+        const saved = await Filesystem.readText(filepath)
         const lines = saved.trim().split("\n")
         expect(lines.length).toBe(lineCount)
         expect(lines[0]).toBe("1")

packages/opencode/test/tool/read.test.ts

@@ -2,6 +2,7 @@ import { describe, expect, test } from "bun:test"
 import path from "path"
 import { ReadTool } from "../../src/tool/read"
 import { Instance } from "../../src/project/instance"
+import { Filesystem } from "../../src/util/filesystem"
 import { tmpdir } from "../fixture/fixture"
 import { PermissionNext } from "../../src/permission/next"
 import { Agent } from "../../src/agent/agent"
@@ -199,10 +200,10 @@ describe("tool.read truncation", () => {
   test("truncates large file by bytes and sets truncated metadata", async () => {
     await using tmp = await tmpdir({
       init: async (dir) => {
-        const base = await Bun.file(path.join(FIXTURES_DIR, "models-api.json")).text()
+        const base = await Filesystem.readText(path.join(FIXTURES_DIR, "models-api.json"))
         const target = 60 * 1024
         const content = base.length >= target ? base : base.repeat(Math.ceil(target / base.length))
-        await Bun.write(path.join(dir, "large.json"), content)
+        await Filesystem.write(path.join(dir, "large.json"), content)
       },
     })
     await Instance.provide({

packages/opencode/test/tool/truncation.test.ts

@@ -1,6 +1,7 @@
 import { describe, test, expect, afterAll } from "bun:test"
 import { Truncate } from "../../src/tool/truncation"
 import { Identifier } from "../../src/id/id"
+import { Filesystem } from "../../src/util/filesystem"
 import fs from "fs/promises"
 import path from "path"
 
@@ -9,7 +10,7 @@ const FIXTURES_DIR = path.join(import.meta.dir, "fixtures")
 describe("Truncate", () => {
   describe("output", () => {
     test("truncates large json file by bytes", async () => {
-      const content = await Bun.file(path.join(FIXTURES_DIR, "models-api.json")).text()
+      const content = await Filesystem.readText(path.join(FIXTURES_DIR, "models-api.json"))
       const result = await Truncate.output(content)
 
       expect(result.truncated).toBe(true)
@@ -69,7 +70,7 @@ describe("Truncate", () => {
     })
 
     test("large single-line file truncates with byte message", async () => {
-      const content = await Bun.file(path.join(FIXTURES_DIR, "models-api.json")).text()
+      const content = await Filesystem.readText(path.join(FIXTURES_DIR, "models-api.json"))
       const result = await Truncate.output(content)
 
       expect(result.truncated).toBe(true)
@@ -88,7 +89,7 @@ describe("Truncate", () => {
       expect(result.outputPath).toBeDefined()
       expect(result.outputPath).toContain("tool_")
 
-      const written = await Bun.file(result.outputPath).text()
+      const written = await Filesystem.readText(result.outputPath!)
       expect(written).toBe(lines)
     })
 
@@ -139,21 +140,21 @@ describe("Truncate", () => {
       const oldTimestamp = Date.now() - 10 * DAY_MS
       const oldId = Identifier.create("tool", false, oldTimestamp)
       oldFile = path.join(Truncate.DIR, oldId)
-      await Bun.write(Bun.file(oldFile), "old content")
+      await Filesystem.write(oldFile, "old content")
 
       // Create a recent file (3 days ago)
       const recentTimestamp = Date.now() - 3 * DAY_MS
       const recentId = Identifier.create("tool", false, recentTimestamp)
       recentFile = path.join(Truncate.DIR, recentId)
-      await Bun.write(Bun.file(recentFile), "recent content")
+      await Filesystem.write(recentFile, "recent content")
 
       await Truncate.cleanup()
 
       // Old file should be deleted
-      expect(await Bun.file(oldFile).exists()).toBe(false)
+      expect(await Filesystem.exists(oldFile)).toBe(false)
 
       // Recent file should still exist
-      expect(await Bun.file(recentFile).exists()).toBe(true)
+      expect(await Filesystem.exists(recentFile)).toBe(true)
     })
   })
 })

packages/opencode/test/util/filesystem.test.ts

@@ -285,4 +285,125 @@ describe("filesystem", () => {
       expect(Filesystem.mimeType("Makefile")).toBe("application/octet-stream")
     })
   })
+
+  describe("writeStream()", () => {
+    test("writes from Web ReadableStream", async () => {
+      await using tmp = await tmpdir()
+      const filepath = path.join(tmp.path, "streamed.txt")
+      const content = "Hello from stream!"
+      const encoder = new TextEncoder()
+      const stream = new ReadableStream({
+        start(controller) {
+          controller.enqueue(encoder.encode(content))
+          controller.close()
+        },
+      })
+
+      await Filesystem.writeStream(filepath, stream)
+
+      expect(await fs.readFile(filepath, "utf-8")).toBe(content)
+    })
+
+    test("writes from Node.js Readable stream", async () => {
+      await using tmp = await tmpdir()
+      const filepath = path.join(tmp.path, "node-streamed.txt")
+      const content = "Hello from Node stream!"
+      const { Readable } = await import("stream")
+      const stream = Readable.from([content])
+
+      await Filesystem.writeStream(filepath, stream)
+
+      expect(await fs.readFile(filepath, "utf-8")).toBe(content)
+    })
+
+    test("writes binary data from Web ReadableStream", async () => {
+      await using tmp = await tmpdir()
+      const filepath = path.join(tmp.path, "binary.dat")
+      const binaryData = new Uint8Array([0x00, 0x01, 0x02, 0x03, 0xff])
+      const stream = new ReadableStream({
+        start(controller) {
+          controller.enqueue(binaryData)
+          controller.close()
+        },
+      })
+
+      await Filesystem.writeStream(filepath, stream)
+
+      const read = await fs.readFile(filepath)
+      expect(Buffer.from(read)).toEqual(Buffer.from(binaryData))
+    })
+
+    test("writes large content in chunks", async () => {
+      await using tmp = await tmpdir()
+      const filepath = path.join(tmp.path, "large.txt")
+      const chunks = ["chunk1", "chunk2", "chunk3", "chunk4", "chunk5"]
+      const stream = new ReadableStream({
+        start(controller) {
+          for (const chunk of chunks) {
+            controller.enqueue(new TextEncoder().encode(chunk))
+          }
+          controller.close()
+        },
+      })
+
+      await Filesystem.writeStream(filepath, stream)
+
+      expect(await fs.readFile(filepath, "utf-8")).toBe(chunks.join(""))
+    })
+
+    test("creates parent directories", async () => {
+      await using tmp = await tmpdir()
+      const filepath = path.join(tmp.path, "nested", "deep", "streamed.txt")
+      const content = "nested stream content"
+      const stream = new ReadableStream({
+        start(controller) {
+          controller.enqueue(new TextEncoder().encode(content))
+          controller.close()
+        },
+      })
+
+      await Filesystem.writeStream(filepath, stream)
+
+      expect(await fs.readFile(filepath, "utf-8")).toBe(content)
+    })
+
+    test("writes with permissions", async () => {
+      await using tmp = await tmpdir()
+      const filepath = path.join(tmp.path, "protected-stream.txt")
+      const content = "secret stream content"
+      const stream = new ReadableStream({
+        start(controller) {
+          controller.enqueue(new TextEncoder().encode(content))
+          controller.close()
+        },
+      })
+
+      await Filesystem.writeStream(filepath, stream, 0o600)
+
+      const stats = await fs.stat(filepath)
+      if (process.platform !== "win32") {
+        expect(stats.mode & 0o777).toBe(0o600)
+      }
+    })
+
+    test("writes executable with permissions", async () => {
+      await using tmp = await tmpdir()
+      const filepath = path.join(tmp.path, "script.sh")
+      const content = "#!/bin/bash\necho hello"
+      const stream = new ReadableStream({
+        start(controller) {
+          controller.enqueue(new TextEncoder().encode(content))
+          controller.close()
+        },
+      })
+
+      await Filesystem.writeStream(filepath, stream, 0o755)
+
+      const stats = await fs.stat(filepath)
+      if (process.platform !== "win32") {
+        expect(stats.mode & 0o777).toBe(0o755)
+      }
+      expect(await fs.readFile(filepath, "utf-8")).toBe(content)
+    })
+  })
 })