NVIDIA NeMo Fabric Installation

Package Installation Method

The nemo-fabric package installs the NeMo Fabric runtime. Harness adapters can run in that environment or in a separate environment with their harness dependencies.

Supported Python Versions

NeMo Fabric supports Python 3.11 through 3.14. Some integrations and adapters have additional requirements. The Hermes Agent adapter does not support Python 3.14, and the Harbor integration requires Python 3.12 or later.

Choose an Installation

The following table shows a representative subset of package expressions and the components they install. The sections that follow describe the complete installation alternatives. A No entry means that the expression does not install that component; the component can already exist in the environment or be managed separately.

An adapter package’s full extra is scoped to the adapter environment and does not install the NeMo Fabric runtime. For Claude and Codex, full is equivalent to harness; both install the supported harness and nemo-relay CLI. For LangChain Deep Agents, full installs the harness and NeMo Relay Python package without the CLI. For Hermes Agent, full installs only the adapter and NeMo Relay Python package; Hermes Agent must be installed separately.

Install the NeMo Fabric Runtime

Install the NeMo Fabric runtime:

$
pip install nemo-fabric

The nemo-fabric package installs the matching NeMo Fabric runtime unconditionally.

Install a Complete Runtime and Harness

Use a nemo-fabric harness extra when the runtime, adapter, and harness run in the same Python environment:

$
pip install "nemo-fabric[claude]"
$
pip install "nemo-fabric[codex]"
$
pip install "nemo-fabric[deepagents]"

Each nemo-fabric harness extra installs the corresponding adapter package with its harness extra. You can combine independent nemo-fabric extras. For example, the following command also installs Harbor; the Claude harness extra supplies the Relay CLI, while relay supplies the Relay Python package:

$
pip install "nemo-fabric[claude,harbor,relay]"

The Claude and Codex harness extras install the nemo-relay CLI required for Relay-enabled runs. The root relay extra installs only the Relay Python package for SDK-native integrations.

Install Hermes Agent

Hermes Agent 0.20 and later is no longer installable from PyPI. End users must follow the Hermes Agent installation guide, then install NeMo Fabric and the bare Hermes adapter into the Python environment that runs Hermes Agent:

$
pip install "nemo-fabric[hermes-agent]"

These packages do not install Hermes Agent. For local NeMo Fabric development, check out the pinned Hermes Agent source and synchronize it into the project environment by running this command from the repository root:

$
just install-hermes-agent

Install an Adapter and Harness Without the Runtime

Use an adapter package’s harness extra when a different environment runs NeMo Fabric:

$
pip install "nemo-fabric-adapters-claude[harness]"
$
pip install "nemo-fabric-adapters-codex[harness]"
$
pip install "nemo-fabric-adapters-deepagents[harness]"

This installation mode keeps the runtime dependencies out of the adapter environment. Set ADAPTER_PYTHON in the runtime environment to the adapter environment’s Python interpreter. A Python adapter and its Python harness must use the same interpreter. Use matching NeMo Fabric release versions for the runtime and adapter package unless a different pairing has been explicitly validated.

Add an Adapter to an Existing Harness Environment

Install an adapter package without an extra when the environment already supplies and manages a compatible harness:

$
pip install nemo-fabric-adapters-claude
$
pip install nemo-fabric-adapters-codex
$
pip install nemo-fabric-adapters-deepagents
$
pip install nemo-fabric-adapters-hermes

Bare adapter distributions install only adapter-owned dependencies. They do not install the NeMo Fabric runtime or the harness.

If the existing harness and runtime share an environment, install the runtime and bare adapter together. The following example preserves the existing Codex SDK instead of installing the adapter’s supported SDK version:

$
pip install nemo-fabric nemo-fabric-adapters-codex

Install NeMo Relay

NeMo Relay integration occurs in two ways:

• Python package
• NeMo Relay CLI

The required integration depends on the agent harness. Relay-enabled runs with the Claude and Codex adapters require the nemo-relay CLI.

NeMo Relay Python Package

The root relay extra installs a version of the NeMo Relay Python package known to be compatible with the installed version of NeMo Fabric:

$
pip install "nemo-fabric[relay]"

LangChain Deep Agents and Hermes Agent import the NeMo Relay Python package directly. Their adapter packages provide relay and full extras:

$
pip install "nemo-fabric-adapters-deepagents[relay]"
$
pip install "nemo-fabric-adapters-hermes[relay]"
$
pip install "nemo-fabric-adapters-deepagents[full]"
$
pip install "nemo-fabric-adapters-hermes[full]"

Use relay when the environment already manages the harness. For Deep Agents, use full to install the harness and Relay package together. For Hermes Agent, relay and full install the adapter and Relay package, but neither installs Hermes Agent. Claude and Codex do not provide a relay extra because their adapters launch the external CLI instead of importing this Python package.

NeMo Fabric requires nemo-relay>=0.7.2,<0.8. For Python-backed Relay integrations, NeMo Fabric does not merge user or workspace plugins.toml files with its runtime-owned configuration. Remove or relocate a user plugins.toml or the nearest .nemo-relay/plugins.toml before starting a Relay-enabled Deep Agents or Hermes Agent runtime. System configuration in /etc/nemo-relay/plugins.toml remains administrator controlled.

Migrate Relay Observability Configurations from 0.6

Relay 0.7 requires observability schema version 3. Move flat OpenTelemetry exporter fields into entries under opentelemetry.endpoints. In the Python SDK, replace the removed RelayOtlpConfig model with RelayOpenTelemetryConfig and one or more RelayOpenTelemetryEndpointConfig entries.

NeMo Relay CLI

Claude and Codex harness extras install the compatible CLI binary without the Relay Python package. To install the CLI independently of an adapter, run:

$
pip install "nemo-relay-cli-bin>=0.7.2,<0.8"

On Linux and macOS, install the pinned CLI with the shell installer:

$
curl -fsSL https://raw.githubusercontent.com/NVIDIA/NeMo-Relay/main/install.sh |
$
  NEMO_RELAY_VERSION=0.7.2 sh -s --

On Windows, install the pinned CLI with PowerShell:

1
$env:NEMO_RELAY_VERSION = "0.7.2"
2
irm https://raw.githubusercontent.com/NVIDIA/NeMo-Relay/main/install.ps1 | iex

If cargo-binstall is available, install the pinned CLI with Cargo:

$
cargo binstall nemo-relay-cli --version 0.7.2

After installation, run nemo-relay --version and confirm the version is in the >=0.7.2,<0.8 range. When Relay is enabled with FabricConfig.enable_relay(...), the Claude and Codex adapters start and supervise the CLI gateway automatically.

Source Installation Method

Prerequisites:

• Rust and Cargo
• Python 3.11 through 3.14
• uv
• just 1.50.0+

1. Create a Python virtual environment and activate it (replace 3.13 with your preferred Python version):

$
uv venv -p 3.13 --seed .venv
$
source .venv/bin/activate
$
just install-hermes-agent

2. Build the Rust core and Python libraries.

$
just build-all

The above command will install only those dependencies that are strictly necessary for the build. Alternately If you want to install all optional dependencies, you can run:

$
uv sync --all-groups --all-extras

Then run the build command with the no_uv=true flag to avoid re-installing the dependencies:

$
just no_uv=true build-all