feat(rust): add IVF-SQ bindings

[jamie8johnson]

Adds Rust bindings for the IVF-SQ index, wrapping the C API introduced in v26.06 ("IVF-SQ C API"). Follow-up to the CAGRA serialize/deserialize and search_with_filter wrappers (#2019 lineage).

What

• New rust/cuvs/src/ivf_sq/ module mirroring the cagra module structure: IndexParams / SearchParams builders, Index with build, search, search_with_filter (cuvsFilter bitset), extend, serialize / deserialize, and the n_lists / dim / size getters.
• rust/cuvs-sys/src/bindings.rs regenerated via rust/scripts/generate-bindings.sh — purely additive (cuvsIvfSq* block).

Notes for reviewers

• cuvsIvfSqIndexGetCenters is deliberately not wrapped, matching the cagra and ivf_pq modules — it fills a caller-allocated DLManagedTensor, which has no ergonomic safe-Rust shape yet (commented in index.rs).
• IVF-SQ exposes getters + extend where the ivf_pq Rust module currently doesn't; the C API supports them for both, so this module simply wraps the full practical surface. Happy to trim for symmetry if preferred.

Testing

9 GPU tests (single-process): params builders, build + self-neighbor search, repeated search, getters, extend-from-empty (NULL indices path), bitset-filtered search asserting exclusion, serialize/deserialize round-trip re-verifying search on the loaded index, interior-NUL path rejection. cargo fmt / clippy clean. Validated against both the v26.06.00 tag (conda libcuvs 26.06) and current main — the ivf_sq.h header is byte-identical between the two.

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ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between 2beefce and 0fa1808.

📒 Files selected for processing (1)

• rust/cuvs/src/ivf_sq/index.rs

🚧 Files skipped from review as they are similar to previous changes (1)

• rust/cuvs/src/ivf_sq/index.rs

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📝 Walkthrough

Summary by CodeRabbit

• New Features

  • Added IVF-SQ (IVF-Scalar Quantization) approximate nearest-neighbor indexing: build, search (with optional filtering), extend, and save/load.
  • Exposed configurable index and search parameters and index property queries.
  • Public API surface updated to include the new IVF-SQ module and types.

• Tests

  • Added unit tests covering build/search/extend/serialize-deserialize and parameter behavior.

Walkthrough

Adds Rust FFI bindings and safe Rust wrappers for an IVF‑SQ approximate nearest‑neighbor index: parameter types, search parameters, Index wrapper (build/search/extend/serialize/deserialize), module exports, and unit tests.

Changes

IVF-SQ Approximate Neighbor Index

Layer / File(s)	Summary
FFI Bindings and C Contract rust/cuvs-sys/src/bindings.rs	C FFI definitions for cuvsIvfSqIndexParams, cuvsIvfSqSearchParams, cuvsIvfSqIndex handle, and core operations: cuvsIvfSqBuild, cuvsIvfSqSearch, cuvsIvfSqExtend, cuvsIvfSqSerialize/cuvsIvfSqDeserialize, plus metadata getters.
Parameter Configuration Wrappers rust/cuvs/src/ivf_sq/index_params.rs, rust/cuvs/src/ivf_sq/search_params.rs	Rust IndexParams and SearchParams wrappers with fluent setters, Debug impls, Drop cleanup, and unit tests verifying underlying fields.
Index Type and Core Operations rust/cuvs/src/ivf_sq/index.rs	Index wrapper providing build(), new(), search(), search_with_filter(), extend(), n_lists()/dim()/size(), serialize()/deserialize(), Drop, and GPU-based unit tests covering search, extend, filtering, and persistence.
Module Declaration and Public Exports rust/cuvs/src/ivf_sq/mod.rs, rust/cuvs/src/lib.rs	Module-level documentation with example, submodule wiring, and re-exports of Index, IndexParams, and SearchParams; registers ivf_sq in the crate.

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~45 minutes

Possibly related PRs

• rapidsai/cuvs#1913: Introduces the underlying C IVF‑SQ API that these Rust bindings consume.
• rapidsai/cuvs#1910: Implements the C-level IVF‑SQ index and core operations referenced by the new bindings.

Suggested labels

improvement, non-breaking, Rust

Suggested reviewers

• robertmaynard
• AyodeAwe
• dantegd

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'feat(rust): add IVF-SQ bindings' directly and concisely summarizes the main change: adding Rust bindings for the IVF-SQ index. It is clear, specific, and accurately represents the primary objective of the changeset.
Description check	✅ Passed	The description is directly related to the changeset, providing context about the IVF-SQ C API bindings, explaining the module structure, implementation details, design decisions (e.g., why cuvsIvfSqIndexGetCenters is not wrapped), and comprehensive testing information.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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