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mellea.backends.adapters.adapter

Adapter classes for adding fine-tuned modules to inference backends.

The primary public surface is :func:AdapterMixin.resolve_adapter (find or lazily register an adapter by capability name) and :meth:AdapterMixin._find_adapter (look up a registered adapter). :class:AdapterMixin is mixed into backends that support runtime adapter loading and unloading.

LocalHFAdapter, IntrinsicAdapter, and EmbeddedIntrinsicAdapter are deprecation shims retained for backwards compatibility. They satisfy isinstance(x, _core.Adapter) but delegate all behaviour to the new dataclass. get_adapter_for_intrinsic is similarly deprecated; prefer resolve_adapter.

Functions​

FUNC get_adapter_for_intrinsic ​

get_adapter_for_intrinsic(intrinsic_name: str, intrinsic_adapter_types: list[AdapterType] | tuple[AdapterType, ...], available_adapters: dict[str, T]) -> T | None

Find an adapter from a dict of available adapters based on the adapter function name and its allowed adapter types.

Args:

  • intrinsic_name: The name of the adapter function, e.g. "answerability".
  • intrinsic_adapter_types: The adapter types allowed for this adapter function, e.g. [AdapterType.ALORA, AdapterType.LORA].
  • available_adapters: The available adapters to choose from; maps adapter.qualified_name to the adapter object.

Returns:

  • T | None: The first matching adapter found, or None if no match exists.

Classes​

CLASS Adapter ​

An adapter that can be added to a single backend.

An adapter can only be registered with one backend at a time. Use adapter.qualified_name when referencing the adapter after adding it.

Args:

  • name: Human-readable name of the adapter.
  • adapter_type: Enum describing the adapter type (e.g. AdapterType.LORA or AdapterType.ALORA).

Attributes:

  • qualified_name: Unique name used for loading and lookup; formed as "<name>_<adapter_type.value>".
  • backend: The backend this adapter has been added to, or None if not yet added.
  • path: Filesystem path to the adapter weights; set when the adapter is added to a backend.

CLASS LocalHFAdapter ​

Abstract adapter subclass for locally loaded Hugging Face model backends.

Subclasses must implement get_local_hf_path to return the filesystem path from which adapter weights should be loaded given a base model name.

Methods:

FUNC get_local_hf_path ​

get_local_hf_path(self, base_model_name: str) -> str

Return the local filesystem path from which adapter weights should be loaded.

Args:

  • base_model_name: The base model name; typically the last component of the Hugging Face model ID (e.g. "granite-4.0-micro").

Returns:

  • Filesystem path to the adapter weights directory.

CLASS IntrinsicAdapter ​

Deprecated shim for adapters that implement adapter functions.

.. deprecated:: Use :class:~mellea.backends.adapters.Adapter directly. IntrinsicAdapter will be removed in a future release (Epic #929, issue #1144).

Subtype of :class:Adapter for models that:

  • implement adapter functions
  • are packaged as LoRA or aLoRA adapters on top of a base model
  • use the shared model loading code in mellea.formatters.granite.intrinsics
  • use the shared input and output processing code in mellea.formatters.granite.intrinsics

Args:

  • intrinsic_name: Name of the adapter function (e.g. "answerability"); the adapter's qualified_name will be derived from this.
  • adapter_type: Enum describing the adapter type; defaults to AdapterType.ALORA.
  • config_file: Path to a YAML config file defining the adapter function's I/O transformations; mutually exclusive with config_dict.
  • config_dict: Dict defining the adapter function's I/O transformations; mutually exclusive with config_file.
  • base_model_name: Base model name used to look up the I/O processing config when neither config_file nor config_dict are provided.

Attributes:

  • intrinsic_name: Name of the adapter function this adapter implements.
  • intrinsic_metadata: Catalog metadata for the adapter function.
  • base_model_name: Base model name provided at construction, if any.
  • adapter_type: The adapter type (LORA or ALORA).
  • config: Parsed I/O transformation configuration for the adapter function.

.. note:: identity, io_contract, and weights are Phase 1 internal scaffolding populated in __init__ to satisfy the new :class:~mellea.backends.adapters.Adapter protocol. They are not meaningful consumer-facing attributes; io_contract and weights raise :exc:NotImplementedError and will be replaced in Phase 2 (issues #1137, #1138).

Methods:

FUNC get_local_hf_path ​

get_local_hf_path(self, base_model_name: str) -> str

Return the local filesystem path from which adapter weights should be loaded.

Downloads the adapter weights if they are not already cached locally.

Args:

  • base_model_name: The base model name; typically the last component of the Hugging Face model ID (e.g. "granite-3.3-8b-instruct").

Returns:

  • Filesystem path to the downloaded adapter weights directory.

FUNC download_and_get_path ​

download_and_get_path(self, base_model_name: str) -> str

Download the required adapter function files if necessary and return the path to them.

Args:

  • base_model_name: the base model; typically the last part of the Hugging Face model id like "granite-3.3-8b-instruct"

Returns:

  • a path to the files

CLASS AdapterMixin ​

Mixin class for backends capable of utilizing adapters.

Attributes:

  • base_model_name: The short model name used to identify adapter variants (e.g. "granite-3.3-8b-instruct" for "ibm-granite/granite-3.3-8b-instruct").

Methods:

FUNC base_model_name ​

base_model_name(self) -> str

Return the short model name used for adapter variant lookup.

Returns:

  • The base model name (e.g. "granite-3.3-8b-instruct").

FUNC add_adapter ​

add_adapter(self, *args, **kwargs)

Register an adapter with this backend so it can be loaded later.

The adapter must not already have been added to a different backend.

Args:

  • args: Positional arguments forwarded to the concrete implementation.
  • kwargs: Keyword arguments forwarded to the concrete implementation.

FUNC load_adapter ​

load_adapter(self, adapter_qualified_name: str)

Load a previously registered adapter into the underlying model.

The adapter must have been registered via add_adapter before calling this method.

Args:

  • adapter_qualified_name: The adapter.qualified_name of the adapter to load.

FUNC unload_adapter ​

unload_adapter(self, adapter_qualified_name: str)

Unload a previously loaded adapter from the underlying model.

Args:

  • adapter_qualified_name: The adapter.qualified_name of the adapter to unload.

FUNC list_adapters ​

list_adapters(self) -> list[str]

Return the qualified names of all adapters currently loaded in this backend.

Returns:

  • list[str]: Qualified adapter names for all adapters that have been loaded via load_adapter.

Raises:

  • NotImplementedError: If the concrete backend subclass has not implemented this method.

FUNC resolve_adapter ​

resolve_adapter(self, name: str) -> _AdapterCore

Find or lazily register an adapter by capability name.

Default implementation preserves Phase 0 behaviour, using the internal _added_adapters dict that concrete backends maintain. Override in Phase 2 (issue #1138) to implement proper lifecycle management.

Args:

  • name: Capability name (e.g. "answerability").

Returns:

  • The registered adapter with the given capability.

Raises:

  • ValueError: If the backend has no model ID.
  • KeyError: If the adapter cannot be found after registration.

FUNC adapter_scope ​

adapter_scope(self, adapter: '_AdapterCore | None')

Context manager wrapping adapter activation and deactivation.

Phase 1 stub — yields immediately (no-op). Phase 2 (issue #1138) wires in adapter.weights.activate() and adapter.weights.deactivate().

Args:

  • adapter: The adapter to activate, or None (no-op in Phase 1).

CLASS EmbeddedIntrinsicAdapter ​

Deprecated shim for adapter functions embedded in a Granite Switch model.

.. deprecated:: Use :class:~mellea.backends.adapters.Adapter directly. EmbeddedIntrinsicAdapter will be removed in a future release (Epic #929, issue #1144).

Unlike PEFT-based adapters that are loaded into the model at runtime, embedded adapters are already baked into the model weights and activated via control tokens injected by the model's chat template. Only the I/O transformation config (io.yaml) is needed; no adapter weights are downloaded or loaded.

Args:

  • intrinsic_name: Name of the adapter function (e.g. "answerability").
  • config: Parsed I/O transformation configuration (from io.yaml).
  • technology: Adapter technology in the switch model — "lora" or "alora". Determines where the control token is placed in the chat template (beginning of sequence for LoRA, before generation prompt for aLoRA).

Attributes:

  • intrinsic_name: Name of the adapter function this adapter implements.
  • config: Parsed I/O transformation configuration.
  • technology: "lora" or "alora".

.. note:: identity, io_contract, and weights are Phase 1 internal scaffolding populated in __init__ to satisfy the new :class:~mellea.backends.adapters.Adapter protocol. They are not meaningful consumer-facing attributes; io_contract and weights raise :exc:NotImplementedError and will be replaced in Phase 2 (issues #1137, #1138).

Methods:

FUNC from_model_directory ​

from_model_directory(model_path: str | pathlib.Path, intrinsic_name: str | None = None) -> list['EmbeddedIntrinsicAdapter']

Load embedded adapters from a Granite Switch model directory.

Reads adapter_index.json and the corresponding io_configs/*/io.yaml files from the model directory.

Args:

  • model_path: Path to a Granite Switch model directory that contains adapter_index.json and io_configs/.
  • intrinsic_name: If provided, only load the adapter matching this adapter function name. None loads all adapters.

Returns:

  • list[EmbeddedIntrinsicAdapter]: One adapter per entry in the index.

Raises:

  • FileNotFoundError: If adapter_index.json is missing.
  • ValueError: If an io.yaml file listed in the index cannot be found or if no adapters are found.

FUNC from_hub ​

from_hub(repo_id: str, revision: str = 'main', cache_dir: str | None = None, intrinsic_name: str | None = None) -> list['EmbeddedIntrinsicAdapter']

Load embedded adapters from a Granite Switch model on Hugging Face Hub.

Downloads adapter_index.json and the io_configs/ directory, then delegates to :meth:from_model_directory.

Args:

  • repo_id: Hugging Face Hub repository ID (e.g. "ibm-granite/granite-switch-micro").
  • revision: Git revision to download from.
  • cache_dir: Local cache directory; None for the default.
  • intrinsic_name: If provided, only load the adapter matching this adapter function name. None loads all adapters.

Returns:

  • list[EmbeddedIntrinsicAdapter]: One adapter per entry in the index.

Raises:

  • ImportError: If huggingface_hub is not installed.
  • FileNotFoundError: If adapter_index.json is missing (delegated from :meth:from_model_directory).
  • ValueError: If no adapters are found (delegated from :meth:from_model_directory).

FUNC from_source ​

from_source(source: str, revision: str = 'main', cache_dir: str | None = None, intrinsic_name: str | None = None) -> list['EmbeddedIntrinsicAdapter']

Load embedded adapters from a local directory or Hugging Face Hub.

Automatically detects whether source is a local filesystem path or a Hugging Face Hub repo ID, and delegates accordingly.

Args:

  • source: Local path to a model directory, or a Hugging Face Hub repo ID (e.g. "ibm-granite/granite-switch-micro").
  • revision: Git revision (only used for Hub downloads).
  • cache_dir: Cache directory (only used for Hub downloads).
  • intrinsic_name: If provided, only load the adapter matching this adapter function name. None loads all adapters.

Returns:

  • list[EmbeddedIntrinsicAdapter]: One adapter per entry in the index.

CLASS CustomIntrinsicAdapter ​

Deprecated shim for user-defined custom adapter functions.

.. deprecated:: Use :class:~mellea.backends.adapters.Adapter directly. CustomIntrinsicAdapter will be removed in a future release (Epic #929, issue #1144).

This class has the same functionality as IntrinsicAdapter, except that its constructor monkey-patches Mellea global variables to enable the backend to load the user's adapter.

Args:

  • model_id: The Hugging Face model ID used for downloading model weights; expected format is "<user-id>/<repo-name>".
  • intrinsic_name: Catalog name for the adapter function; defaults to the repository name portion of model_id if not provided.
  • base_model_name: The short name of the base model (NOT its repo ID).