fix(security): enforce explicit trust for local ST modules

[svonava]

Sentence Transformers 5.x can execute classes referenced by a local checkpoint even when the caller sets trust_remote_code=False. Route the existing SIE dense, sparse, cross-encoder, native causal cross-encoder and sparse-vision constructors through a load-only boundary that requires explicit True for custom modules and tokenizers.

The boundary handles recursive Router/Asym and WordEmbeddings loading, legacy class references, renamed constructor arguments and ordinary mapping containers. False and None cannot be elevated by nested options. Temporary instance bindings are removed on success and failure; library globals, returned native classes and existing trust defaults remain unchanged. The boundary does not wrap inference methods. Explicit True uses the original constructor directly.

The denying path supports the inspected Sentence Transformers 5.4.1, 5.6.0 and 5.7.0 implementations and fails closed for other versions. The trusted path does not depend on their private layouts. Server metadata, the default and Transformers 5 bundles, and the authoritative root lock now consistently pin sentence-transformers==5.7.0, preventing a fresh install from selecting an unsupported denying-path implementation. All unrelated locked package records remain unchanged. The version itself is not the security fix; the boundary is still required. This addresses the Sentence Transformers local-loading boundary discussed in #802; the separate Transformers attention/kernel configuration issue and #653's human review hold remain open.

Validation: 194 real-wheel controls pass on each of the three supported versions. The final ST 5.7.0 / Transformers 4.57.6 stack passes 528 focused adapter, CPU-alignment, LoRA and dependency-contract controls; 32 actual-adapter controls also pass with the Transformers 5.17 bundle floor. Independent adversarial controls cover recursive loads, alias and Mapping elevation attempts, concurrent trusted/untrusted callers, native forward identity and temporary-binding cleanup. An actual 5.0 compatibility control preserves the trusted path and refuses the unsupported denying path. Tests use tiny local checkpoints, owned dynamic-module caches and explicit execution markers; no downloads, GPU qualification or inference-performance claim is involved. An independent same-checkpoint CPU float32 comparison between ST 5.4.1 and 5.7.0 matches dense/raw-normalized and cross-encoder outputs exactly for batches of 1, 2 and 4. Upstream 5.7 changes native module dispatch and some preprocessing/device-map handling; these bounded checks do not establish arbitrary-model, multimodal, GPU or throughput equivalence. Ruff, formatting, scoped type checks and the frozen lock check pass.

Summary by CodeRabbit

• New Features
  • Sparse vision models are supported with Sentence Transformers 5.7.0.
  • Sentence-transformer, sparse-encoder, and cross-encoder models share a consistent loading process.
• Bug Fixes
  • When remote-code trust is disabled or unspecified, model and tokenizer references are limited to supported native implementations. Custom remote code runs only when trust is explicitly enabled.
  • Unsupported library versions, model references, and nested settings that attempt to enable remote-code trust are rejected.
• Compatibility
  • Sentence Transformers is pinned to version 5.7.0 across supported bundles.

[svonava]

@coderabbitai full review

Please review exact head 33e137edcb74f8e1d9c7103e0469f832d95cb5e1, especially recursive Router/tokenizer loading, renamed or Mapping-based nested trust overrides, concurrent trusted/untrusted constructors, and cleanup of temporary instance bindings. The denying path is explicitly limited to the inspected ST implementations; current trust defaults and native inference methods remain unchanged. The separate Transformers configuration/kernel boundary discussed in #802 is outside this PR.

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📝 Walkthrough

Adds load_sentence_transformer as a guarded loading boundary for supported Sentence Transformers versions. Dense, sparse, vision, and cross-encoder adapters use it to load models. Tests cover trust validation, native class resolution, adapter integration, and loader behavior.

Changes: Sentence Transformers loading

Layer / File(s)	Summary
Guarded native loading packages/sie_server/src/sie_server/adapters/_sentence_transformer_trust.py, packages/sie_server/tests/adapters/test_sentence_transformer_trust.py, packages/sie_server/bundles/default.yaml, packages/sie_server/bundles/transformers5.yaml, packages/sie_server/pyproject.toml, packages/sie_server/tests/config/test_native_zerank_catalog.py	Adds a loader that permits explicit trusted construction and validates untrusted construction. The guarded path checks nested kwargs, forces nested trust to False, and resolves class references from native exports. Pins sentence-transformers to version 5.7.0. Tests cover custom references, malformed inputs, native behavior, supported versions, and concurrent loads.
Adapter loading integration packages/sie_server/src/sie_server/adapters/{sentence_transformer,cross_encoder,native_causal_cross_encoder,st_sparse_vision}/..., packages/sie_server/src/sie_server/adapters/cross_encoder/{_cpu_alignment,_lora}.py, packages/sie_server/tests/adapters/{test_cross_encoder_cpu_alignment,test_native_causal_cross_encoder,test_st_sparse_vision}.py	Routes dense, sparse, vision, and cross-encoder model construction through load_sentence_transformer. Updates adapter tests to mock the new loading boundary. Allows None in the CPU alignment function’s model type and checks supported model types in LoRA binding.

Sequence Diagram(s)

sequenceDiagram
  participant Adapter
  participant Loader as load_sentence_transformer
  participant Boundary as _NativeLoadBoundary
  participant Constructor as Sentence Transformers constructor
  Adapter->>Loader: Pass model class and load arguments
  Loader->>Boundary: Set up native reference resolution
  Loader->>Constructor: Construct with nested trust disabled
  Constructor->>Boundary: Resolve nested module or tokenizer reference
  Boundary-->>Constructor: Return native class or guarded loader facade
  Loader-->>Adapter: Return constructed model

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Suggested reviewers: krisztian-gajdar

Priority: ⬆️ High

Merge Risk: ⚪ Minimal · up to 6466f

These incremental changes do not establish a production behavior change or actionable merge risk.

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Check name	Status	Explanation	Resolution
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Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely describes the primary security change: requiring explicit trust for local Sentence Transformers modules.

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Inline comments:
Review comments at
@packages/sie_server/src/sie_server/adapters/_sentence_transformer_trust.py:
- Line 18: Align the package and bundle dependency declarations used by
load_sentence_transformer with _SUPPORTED_VERSIONS: pin each deployment to an
exact version in the allowlist or ensure its lockfile resolves to one of those
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• packages/sie_server/src/sie_server/adapters/_sentence_transformer_trust.py
• packages/sie_server/src/sie_server/adapters/cross_encoder/__init__.py
• packages/sie_server/src/sie_server/adapters/native_causal_cross_encoder/adapter.py
• packages/sie_server/src/sie_server/adapters/sentence_transformer/__init__.py
• packages/sie_server/src/sie_server/adapters/st_sparse_vision/adapter.py
• packages/sie_server/tests/adapters/test_cross_encoder_cpu_alignment.py
• packages/sie_server/tests/adapters/test_native_causal_cross_encoder.py
• packages/sie_server/tests/adapters/test_sentence_transformer_trust.py
• packages/sie_server/tests/adapters/test_st_sparse_vision.py

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[svonava]

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Please review exact head 11d3802f12305907bfdf699850b37bea7002276f. Finding #4306986208 is addressed: server/default/Transformers 5 declarations and root lock all select sentence-transformers==5.7.0; a contract test prevents drift from the supported load boundary. Unrelated locked packages and helper/adapter production code are unchanged. The version itself is not claimed to fix local trust; the load boundary remains necessary.

The final stack passes 528 focused controls, with 32 additional controls on the TF5 bundle floor. Full CI is running for this head.

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only still-valid issues, skip the rest with a brief reason, keep changes
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Inline comments:
Review comments at @packages/sie_server/bundles/default.yaml:
- Line 66: Update the dependency assertion in
test_native_catalog_pin_profile_and_bundle() to expect ==5.7.0, matching the
sentence-transformers pin in the default bundle; if the intended contract is
still the broader range, retain that range in the bundle instead.

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Please review final head 7dba8ecbc74674ab34d198f0834b677f5750e030. It retains the exact server/default/TF5 ST5.7.0 pin fix from11d3802f and additionally updates one stale catalog-test expectation plus the sparse-vision dependency docstring. The helper and executable adapter code are unchanged; five targeted catalog/dependency checks pass. Full CI is running for this head.

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@coderabbitai review

Please review exact head 6466ffd65c3bf090f4876f6ca26db0d4ea5203b4. The latest correction addresses ST5.7's nullable CrossEncoder.model typing at existing load-time boundaries: explicit admission preserves the same unsupported-model error, and the alignment helper annotation now includes its existing None no-op. Scoring, selection, and the trust helper are unchanged.

Full local Python type checking with actual ST5.7/TF4 passes. All 121 LoRA and 57 alignment controls pass across the retained initial run and the two permission-corrected loopback reruns; the initial sandbox bind failures remain recorded. Fresh full CI is running.

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