[ni (nniiovoo)]

Motivation & Context

NOT over an eq filter on CosmosCollection leaves out records whose field is null, while InMemoryCollection and the other connectors include them. This affects both get(filter=...) and search(filter=...). eq was translated to (IS_DEFINED(x) AND x = @p). In Cosmos SQL, null = @p is undefined, true AND undefined is undefined, and NOT undefined stays undefined, so those items aren't returned. Details and repro in the linked issue.

Description & Review Guide

• What are the major changes? eq is now translated to (IS_DEFINED(x) AND NOT IS_NULL(x) AND x = @p). That's the same guard the in/not_in and ordered operators already use, and matches what the SQL Server connector does for eq. The three exact-SQL test expectations are updated. There's a new NOT-over-eq case on the nullable optional field, and an assertion in the live integration test.
• What is the impact of these changes? Under NOT, null rows are now returned, matching the portable semantics. Top-level eq results are unchanged: Filter rejects eq with None, so null rows never matched before either.
• What do you want reviewers to focus on? The eq branch in _translate_filter. The unit tests pin the generated SQL. Only the opt-in live test (AZURE_COSMOS_VECTOR_TESTS=1, not run in CI) checks returned rows, and I couldn't run it without a Cosmos account. The new assertion runs before the missing record is inserted, so the expected set is {one, three}.

Related Issue

Fixes #8770

Contribution Checklist

• The code builds clean without any errors or warnings
• All unit tests pass, and I have added new tests where possible
• The PR follows the Contribution Guidelines
• This PR is linked to an issue and there is no other open PR for this issue (see Related Issue above).
• This is not a breaking change. If it is a breaking change, add the breaking change label (or add "[BREAKING]" to the title prefix, before or after any language prefix) — a workflow keeps the label and title prefix in sync automatically.

[Copilot]

Copilot review overview

🟢 Approval recommended

The focused translation change correctly handles Cosmos three-valued logic and is adequately covered by unit and integration tests.

Review effort: Balanced
Findings: None

What changed in this PR

Fixes Cosmos DB negated equality filters so records with null fields match portable connector semantics.

Changes:

• Adds an explicit null guard to equality predicates.
• Updates SQL translation tests and adds null-field regression coverage.
• Verifies behavior against live Cosmos DB integration tests.

File	Description
python/​packages/​azure-cosmos/​agent_framework_azure_cosmos/​_vector_store.py	Adds null-safe equality translation.
python/​packages/​azure-cosmos/​tests/​azure_cosmos/​test_vector_store.py	Updates SQL expectations and regression coverage.
python/​packages/​azure-cosmos/​tests/​azure_cosmos/​test_vector_store_integration.py	Verifies negated equality includes null records.

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[ni (nniiovoo)]

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