[6londe]

Reference-count filters raise AssertionError when collection aggregation uses the GraphQL fallback on Weaviate < 1.29:

collection.aggregate.over_all(
    filters=Filter.by_ref_count("ref").greater_than(0)
)

_FilterToREST.__to_path() does not handle _CountRef and falls through to the multi-target-reference assertion. Serialize its reference property as the GraphQL path, which is how the existing integer operand expresses a reference-count comparison. Add regression tests for both standalone and compound filters.

Validation on current main d1e185e:

• Before: both new regression cases fail. Against a real isolated Weaviate 1.28.16 instance with two objects and one reference, raw GraphQL returns count 1, while both public sync and async aggregate calls raise AssertionError.
• After: both public SDK calls return count 1, matching raw GraphQL.
• pytest test/collection/test_filter.py test/collection/test_aggregates.py -q: 36 passed.
• pytest test -q: 566 passed, 1 skipped (Python 3.12).
• pre-commit run --files weaviate/collections/filters.py test/collection/test_filter.py and normal commit hooks: all passed, including stub generation, Ruff, flake8/docstrings and project Pyright.

The full integration/server-version matrix was not run. The gRPC serializer is unchanged.

AI disclosure: Codex investigated, generated, reviewed and tested this change; no independent human review is claimed.

[orca-security-eu]

Orca Security Scan Summary

Status	Check	Issues by priority
Passed	Infrastructure as Code	0   0   0   0	View in Orca
Passed	SAST	0   0   0   0	View in Orca
Passed	Secrets	0   0   0   0	View in Orca
Passed	Vulnerabilities	0   0   0   0	View in Orca

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