fix: add resetRadiusThreshold() mitigation for radius threshold leak (closes #200) - #209
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August 30, 2026 19:41
…loses #200) A radius-filtered Flat/IVF query poisons the thread-local search context: subsequent radius-less queries on the same thread return only the radius-filtered subset (upstream: no-op Flat/IVF context reset, radius>0 gate in _prepare_for_search). Add ZVecCollection::resetRadiusThreshold() plus ZVec::RADIUS_THRESHOLD_RESET (FLT_MAX) purge query and regression test test_radius_threshold_leak.phpt.
- IP metrics: radius DOES filter docs with similarity < -radius (e.g. opposite vectors) — the leak can occur for IP too, and the purge restores the missing negative-similarity docs (empirically verified). Replaces the false 'radius never filters / leak cannot occur / no-op' claims in CHANGELOG, method docblock, faq and decisions. - ZVec:: not ZVecCollection:: (no such class). - RADIUS_THRESHOLD_RESET rationale: PHP_FLOAT_MAX overflows to inf in float32 (not 'rejected by the FFI'); FLT_MAX mirrors upstream reset_threshold(). Fix MipsL2 '-1' misattribution (denormalize is a sign flip via its InnerProduct query metric; the -= 1 shift is cosine). - Docblock: purge query is always dense fp32 — sparse fields cannot be purged through this method.
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Description
Closes #200
A radius-filtered Flat/IVF query poisons the thread-local search context in upstream zvec (threshold cached on a
thread_localcontext shared per index type; Flat/IVFreset()is a no-op; radius gated byif (radius > 0.0f)): every later radius-less query on that thread — refiner, plain, any field of the same index type, even other collections — silently returns only the radius-filtered subset.Changes
ZVec::RADIUS_THRESHOLD_RESET(FLT_MAX) — purge value mirroring upstreamreset_threshold()ZVec::resetRadiusThreshold(string $fieldName, array $vector)— throwaway topk-1 purge query that overwrites the leaked thresholdtest_radius_threshold_leak.phpt(documents the leak + recovery)Empirical verification (built dylib, zvec v0.6.0)
-radius(opposite vectors) — the leak occurs for IP too, and the purge restores the missing docsTesting