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JavaScriptdeepagentsbackendsCompositeBackend
Class●Since v1.4

CompositeBackend

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class CompositeBackend

Used in Docs

  • Agent Client Protocol (ACP)
  • Backends
  • Context engineering in Deep Agents
  • Going to production
  • Memory

Constructors

Properties

Methods

View source on GitHub
constructor
constructor
property
id: string
method
downloadFiles→ MaybePromise<FileDownloadResponse[]>
method
edit→ Promise<EditResult>
method
execute→ MaybePromise<ExecuteResponse>
method
glob→ Promise<GlobResult>
method
grep→ Promise<GrepResult>
method
ls→ Promise<LsResult>
method
read→ Promise<ReadResult>
method
readRaw→ Promise<ReadRawResult>
method
uploadFiles→ MaybePromise<FileUploadResponse[]>
method
write→ Promise<WriteResult>

Backend that routes file operations to different backends based on path prefix.

This enables hybrid storage strategies like:

  • /memories/ → StoreBackend (persistent, cross-thread)
  • Everything else → StateBackend (ephemeral, per-thread)

The CompositeBackend handles path prefix stripping/re-adding transparently.

Unique identifier for the sandbox backend

Download multiple files from the sandbox. Implementations must support partial success.

Edit a file by replacing string occurrences.

Uses downloadFiles() to read, performs string replacement in TypeScript, then uploadFiles() to write back. No runtime needed on the sandbox host.

Memory-conscious: releases intermediate references early so the GC can reclaim buffers before the next large allocation is made.

Execute a command in the sandbox. This is the only method concrete implementations must provide.

Structured glob matching returning FileInfo objects.

Uses pure POSIX shell (find + stat) via execute() to list all files, then applies glob-to-regex matching in TypeScript. No Python or Node.js needed on the sandbox host.

Glob patterns are matched against paths relative to the search base:

  • * matches any characters except /
  • ** matches any characters including / (recursive)
  • ? matches a single character except /
  • [...] character classes

Search for a literal text pattern in files using grep.

List files and directories in the specified directory (non-recursive).

Uses pure POSIX shell (find + stat) via execute() — works on any Linux including Alpine. No Python or Node.js needed.

Read file content with line numbers.

Uses pure POSIX shell (awk) via execute() — only the requested slice is returned over the wire, making this efficient for large files. Works on any Linux including Alpine (no Python or Node.js needed).

Read file content as raw FileData.

Uses downloadFiles() directly — no runtime needed on the sandbox host.

Upload multiple files to the sandbox. Implementations must support partial success.

Create a new file with content.

Uses downloadFiles() to check existence and uploadFiles() to write. No runtime needed on the sandbox host.