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

---

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.