fix case insensitive lookup for custom text models

[CODING-DARSH]

Fixes #650

Checklist

• Have you followed the guidelines in the Contributing document?
• Have you checked that there are no existing open PRs for the same issue?
• Does the change pass tests locally?
• Have you added a regression test for the fix?

Summary

Custom models can be registered using one casing (e.g. Org/Model) and later instantiated using a different casing (e.g. org/model). TextEmbedding already resolves models case-insensitively, but CustomTextEmbedding later looked up the postprocessing configuration using the original user-provided model name, which could result in a KeyError.

This change uses the canonical resolved model name from self.model_description.model when retrieving the postprocessing configuration.

Changes

• Fix custom text model postprocessing lookup to use the canonical resolved model name.
• Add a regression test covering mixed-case registration and instantiation.

Reproduction

Before

1. Register a custom model as Org/Model.
2. Instantiate TextEmbedding("org/model").
3. Construction can fail with KeyError.

After

1. Register a custom model as Org/Model.
2. Instantiate TextEmbedding("org/model").
3. Construction succeeds and uses the correct postprocessing configuration.

Testing

• Added test_custom_text_model_lookup_is_case_insensitive.
• Verified with:

poetry run pytest tests/test_custom_models.py -k custom_text_model_lookup_is_case_insensitive -q

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Advanced

Run ID: 24a56a04-8400-4e97-94b0-9df22ee1802b

📥 Commits

Reviewing files that changed from the base of the PR and between ff91ff6 and d844fec.

📒 Files selected for processing (2)

• fastembed/text/custom_text_embedding.py
• tests/test_custom_models.py

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📝 Walkthrough

Walkthrough

CustomTextEmbedding now stores the postprocessing configuration lookup in a local variable before assigning pooling and normalization. The test fixture resets the postprocessing mapping and supported-model registries. A new test verifies case-insensitive custom model loading and the configured postprocessing values.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~8 minutes

Change: Bug fix · Severity of issue fixed: Medium

Merge Risk: ⚪ Minimal · up to d844f

The change correctly supports mixed-case custom model construction and adds regression coverage without leaving a concrete merge-blocking risk.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 9 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: fixing case-insensitive lookup for custom text models.
Description check	✅ Passed	The description directly explains the case-insensitive lookup failure, the canonical model-name fix, the regression test, and the targeted test command.
Linked Issues check	✅ Passed	The change meets the coding requirements in [#650]. CustomTextEmbedding.__init__ now retrieves POSTPROCESSING_MAPPING with self.model_description.model, which is the canonical resolved model nam…
Out of Scope Changes check	✅ Passed	The changes remain within [#650]. The fixture reset changes isolate custom-model state between tests, and the removed per-test cleanup is redundant after that centralization. The added test directly v…

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[joein]

thanks for fixing this!