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marc-vercel merged 2 commits into from
Apr 2, 2026
Merged

feat(sandbox): accept string and Uint8Array in writeFiles content #128

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6aca335
feat(sandbox): accept string and Uint8Array in writeFiles content
TooTallNate Apr 1, 2026
ff0c80d
address review: rename FileBuffer to FileData, await writer.end() in …
TooTallNate Apr 2, 2026
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5 changes: 5 additions & 0 deletions .changeset/write-files-string-content.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
---
"@vercel/sandbox": patch
---

Accept `string` and `Uint8Array` in `writeFiles()` content, not just `Buffer`.
6 changes: 5 additions & 1 deletion packages/vercel-sandbox/src/api-client/api-client.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -460,7 +460,11 @@ export class APIClient extends BaseClient {
async writeFiles(params: {
sandboxId: string;
cwd: string;
files: { path: string; content: Buffer; mode?: number }[];
files: {
path: string;
content: string | Uint8Array;
mode?: number;
}[];
extractDir: string;
signal?: AbortSignal;
}) {
Expand Down
68 changes: 64 additions & 4 deletions packages/vercel-sandbox/src/api-client/file-writer.test.ts
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Expand Up @@ -29,9 +29,10 @@ describe("FileWriter", () => {
name: "hello.txt",
content: Buffer.from("Hello world"),
});
writer.end();
const end = writer.end();

const files = await extractFiles(writer.readable);
await end;
expect(files.get("hello.txt")?.toString()).toBe("Hello world");
});

Expand All @@ -42,9 +43,10 @@ describe("FileWriter", () => {
name: "utf8.txt",
content: Buffer.from(content),
});
writer.end();
const end = writer.end();

const files = await extractFiles(writer.readable);
await end;
expect(files.get("utf8.txt")?.toString()).toBe(content);
});

Expand All @@ -58,14 +60,71 @@ describe("FileWriter", () => {
name: "b.txt",
content: Buffer.from("file b"),
});
writer.end();
const end = writer.end();

const files = await extractFiles(writer.readable);
await end;
expect(files.size).toBe(2);
expect(files.get("a.txt")?.toString()).toBe("file a");
expect(files.get("b.txt")?.toString()).toBe("file b");
});

it("writes string content", async () => {
const writer = new FileWriter();
await writer.addFile({
name: "hello.txt",
content: "Hello world",
});
const end = writer.end();

const files = await extractFiles(writer.readable);
await end;
expect(files.get("hello.txt")?.toString()).toBe("Hello world");
});

it("writes multi-byte UTF-8 string content", async () => {
const writer = new FileWriter();
const content = "café ☕ — Grüße aus München 🌍 日本語テスト";
await writer.addFile({
name: "utf8.txt",
content,
});
const end = writer.end();

const files = await extractFiles(writer.readable);
await end;
expect(files.get("utf8.txt")?.toString()).toBe(content);
});

it("writes Uint8Array content", async () => {
const writer = new FileWriter();
const content = new TextEncoder().encode("Hello world");
await writer.addFile({
name: "hello.txt",
content,
});
const end = writer.end();

const files = await extractFiles(writer.readable);
await end;
expect(files.get("hello.txt")?.toString()).toBe("Hello world");
});

it("writes multi-byte UTF-8 Uint8Array content", async () => {
const writer = new FileWriter();
const text = "café ☕ — Grüße aus München 🌍 日本語テスト";
const content = new TextEncoder().encode(text);
await writer.addFile({
name: "utf8.txt",
content,
});
const end = writer.end();

const files = await extractFiles(writer.readable);
await end;
expect(files.get("utf8.txt")?.toString()).toBe(text);
});

it("writes stream content with explicit size", async () => {
const content = Buffer.from("streamed content");
const writer = new FileWriter();
Expand All @@ -74,9 +133,10 @@ describe("FileWriter", () => {
content: Readable.from(content),
size: content.length,
});
writer.end();
const end = writer.end();

const files = await extractFiles(writer.readable);
await end;
expect(files.get("stream.txt")?.toString()).toBe("streamed content");
});
});
14 changes: 9 additions & 5 deletions packages/vercel-sandbox/src/api-client/file-writer.ts
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Expand Up @@ -2,15 +2,15 @@ import zlib from "zlib";
import tar, { type Pack } from "tar-stream";
import { Readable } from "stream";

interface FileBuffer {
interface FileData {
/**
* The name (path) of the file to write.
*/
name: string;
/**
* The content of the file as a Buffer.
* The content of the file.
*/
content: Buffer;
content: string | Uint8Array;
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/**
* The file mode (permissions) to set on the file.
* For example, 0o755 for executable files.
Expand Down Expand Up @@ -62,12 +62,16 @@ export class FileWriter {
* Returns a Promise resolved once the file is written in the
* stream.
*/
async addFile(file: FileBuffer | FileStream) {
async addFile(file: FileData | FileStream) {
return new Promise<void>((resolve, reject) => {
const entry = this.pack.entry(
"size" in file
? { name: file.name, size: file.size, mode: file.mode }
: { name: file.name, size: Buffer.byteLength(file.content), mode: file.mode },
: {
name: file.name,
size: Buffer.byteLength(file.content),
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marc-vercel marked this conversation as resolved.
mode: file.mode,
},
(error) => {
if (error) {
return reject(error);
Expand Down
8 changes: 6 additions & 2 deletions packages/vercel-sandbox/src/sandbox.ts
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Expand Up @@ -703,11 +703,15 @@ export class Sandbox {
* @example
* // Write an executable script
* await sandbox.writeFiles([
* { path: "/usr/local/bin/myscript", content: Buffer.from("#!/bin/bash\necho hello"), mode: 0o755 }
* { path: "/usr/local/bin/myscript", content: "#!/bin/bash\necho hello", mode: 0o755 }
* ]);
*/
async writeFiles(
files: { path: string; content: Buffer; mode?: number }[],
files: {
path: string;
content: string | Uint8Array;
mode?: number;
}[],
opts?: { signal?: AbortSignal },
) {
"use step";
Expand Down
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