Adding files

You can provide files to your agent by uploading them via the Files API and mounting them in the session's container.

Uploading files

First, upload a file using the Files API:

file = client.beta.files.upload(file=Path("data.csv"))
print(f"File ID: {file.id}")

Mounting files in a session

Mount uploaded files into the container by adding them to the resources array when creating a session:

session = client.beta.sessions.create(
    agent=agent.id,
    environment_id=environment.id,
    resources=[
        {
            "type": "file",
            "file_id": file.id,
            "mount_path": "/workspace/data.csv",
        },
    ],
)

A new file_id will be created that references the instance of the file in the session. These copies do not count against your storage limits.

Multiple files

Mount multiple files by adding entries to the resources array:

resources = [
    {"type": "file", "file_id": "file_abc123", "mount_path": "/workspace/data.csv"},
    {"type": "file", "file_id": "file_def456", "mount_path": "/workspace/config.json"},
    {"type": "file", "file_id": "file_ghi789", "mount_path": "/workspace/src/main.py"},
]

A maximum of 100 files is supported per session.

Managing files on a running session

You can add or remove files from a session after creation using the session resources API. Each resource has an id returned when it is added (or listed), which you use for deletes.

resource = client.beta.sessions.resources.add(
    session.id,
    type="file",
    file_id=file.id,
)
print(resource.id)  # "sesrsc_01ABC..."

List all resources on a session with resources.list. To remove a file, call resources.delete with the resource ID:

listed = client.beta.sessions.resources.list(session.id)
for entry in listed.data:
    print(entry.id, entry.type)

client.beta.sessions.resources.delete(resource.id, session_id=session.id)

Listing and downloading session files

Use the Files API to list files scoped to a session and download them.

# List files associated with a session
files = client.beta.files.list(
    scope_id="sesn_abc123",
    betas=["managed-agents-2026-04-01"],
)
for f in files:
    print(f.id, f.filename)

# Download a file
content = client.beta.files.download(files.data[0].id)
content.write_to_file("output.txt")

Supported file types

The agent can work with any file type, including:

• Source code (.py, .js, .ts, .go, .rs, etc.)
• Data files (.csv, .json, .xml, .yaml)
• Documents (.txt, .md)
• Archives (.zip, .tar.gz) - the agent can extract these using bash
• Binary files - the agent can process these with appropriate tools

File paths

• Files are mounted at the exact path you specify
• Parent directories are created automatically
• Paths should be absolute (starting with /)