Validate explicitly-provided adapter_model path in ModelParams

[idoudali]

Depends on #2319

Description

Fail fast with ConfigFileNotFoundError when adapter_model is set but doesn't point to a directory containing adapter_config.json, preventing confusing downstream errors during model loading.

Fixes OPE-1851

Related issues

Fixes # (issue)

Before submitting

• This PR only changes documentation. (You can ignore the following checks in that case)
• Did you read the contributor guideline Pull Request guidelines?
• Did you link the issue(s) related to this PR in the section above?
• Did you add / update tests where needed?

Reviewers

At least one review from a member of oumi-ai/oumi-staff is required.

[Copilot]

Pull request overview

This PR makes ModelParams.finalize_and_validate() fail fast when an explicitly provided adapter_model doesn’t resolve to an adapter_config.json, raising ConfigFileNotFoundError to avoid later, more confusing model-loading failures.

Changes:

• Add explicit validation of adapter_model via find_adapter_config_file() and raise ConfigFileNotFoundError when not found.
• Update and extend unit tests to cover valid explicit adapter dirs and multiple failure modes (missing path, missing config, HF validation error).

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 3 comments.

File	Description
src/oumi/core/configs/params/model_params.py	Adds explicit adapter_model validation and raises ConfigFileNotFoundError when adapter_config.json can’t be resolved.
tests/unit/core/configs/params/test_model_params.py	Updates existing adapter_model test to use a real temp adapter dir and adds new negative tests for explicit adapter_model validation.

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[Copilot]

The exception handling here discards the underlying exception by setting adapter_config_file = None. Consider capturing the exception as e and raising ConfigFileNotFoundError(...) from e (or at least logging type(e).__name__ at debug) so users can tell whether the failure was a missing local path, an invalid HF repo id, permission error, etc.

Suggested change

	except (OSError, HFValidationError):
	adapter_config_file = None
	if not adapter_config_file or not Path(adapter_config_file).is_file():
	raise ConfigFileNotFoundError(
	f"adapter_config.json not found for adapter_model: "
	f"'{self.adapter_model}'. Ensure this path points to a valid "
	f"LoRA adapter directory containing adapter_config.json."
	except (OSError, HFValidationError) as e:
	raise ConfigFileNotFoundError(
	f"adapter_config.json not found for adapter_model: "
	f"'{self.adapter_model}'. Ensure this path points to a valid "
	f"LoRA adapter directory containing adapter_config.json."
	) from e
	if not Path(adapter_config_file).is_file():
	raise ConfigFileNotFoundError(
	f"adapter_config.json not found for adapter_model: "
	f"'{self.adapter_model}'. Ensure this path points to a valid "
	f"LoRA adapter directory containing adapter_config.json."

[Copilot]

The error text says "Ensure this path points to a valid LoRA adapter directory" but adapter_model can also be a Hugging Face Hub repo id (and failures can be auth/network-related). Consider wording this as "local directory or HF Hub repo id containing adapter_config.json" to avoid misleading guidance.

Suggested change

	f"'{self.adapter_model}'. Ensure this path points to a valid "
	f"LoRA adapter directory containing adapter_config.json."
	f"'{self.adapter_model}'. Ensure this value is a local directory "
	f"or HF Hub repo id containing adapter_config.json and that it is "
	f"accessible (e.g., correct name, permissions, and network)."

[Copilot]

This test hardcodes an absolute "/nonexistent/..." path. To avoid brittleness across environments (and to keep tests hermetic), prefer using tmp_path / "does_not_exist" (without creating it) as the nonexistent adapter path.

Suggested change

	def test_explicit_adapter_model_nonexistent_path():
	"""Explicitly-set adapter_model that doesn't exist raises error."""
	params = ModelParams(
	model_name="base_model", adapter_model="/nonexistent/adapter_path"
	def test_explicit_adapter_model_nonexistent_path(tmp_path: Path):
	"""Explicitly-set adapter_model that doesn't exist raises error."""
	params = ModelParams(
	model_name="base_model", adapter_model=str(tmp_path / "does_not_exist")

[sentry]

Bug: The code raises ConfigFileNotFoundError, which is not defined, causing a NameError at runtime. The correct exception class is OumiConfigFileNotFoundError.
_{Severity: CRITICAL}

Suggested Fix

Replace the undefined ConfigFileNotFoundError on line 322 with the correct, imported exception class OumiConfigFileNotFoundError. Also, update the corresponding test cases in tests/unit/core/configs/params/test_model_params.py to expect OumiConfigFileNotFoundError.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent.
Verify if this is a real issue. If it is, propose a fix; if not, explain why it's not
valid.

Location: src/oumi/core/configs/params/model_params.py#L322-L326

Potential issue: The validation logic for `adapter_model` raises
`ConfigFileNotFoundError` if an `adapter_config.json` file is not found. However, this
exception class is not defined or imported. The correct, imported exception class is
`OumiConfigFileNotFoundError`, which is used in a similar check elsewhere in the same
file. This will cause the application to crash with a `NameError: name
'ConfigFileNotFoundError' is not defined` instead of providing the intended
user-friendly error message. The associated tests also incorrectly try to catch the
undefined exception.

_{Did we get this right? 👍 / 👎 to inform future reviews.}