zhuyongxin
376ad0c241
Add configurable hybrid mode on KnowledgeSearchPort that fuses dense unfiltered, dense filtered, and lexical ranks via RRF while preserving dense-compatible threshold scores. Archives Delivery 2 OpenSpec change.
47 lines
1.9 KiB
Markdown
47 lines
1.9 KiB
Markdown
# rag-hybrid-search Specification
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## Purpose
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TBD - created by archiving change rag-hybrid-search-rrf. Update Purpose after archive.
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## Requirements
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### Requirement: Knowledge search SHALL support configurable dense and hybrid modes
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The knowledge search port SHALL support `retrieval.search.mode` values `dense` and `hybrid`. Default SHALL be `dense` for backward-compatible behavior.
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#### Scenario: Dense mode single path
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- **WHEN** mode is dense
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- **THEN** the port SHALL perform a single dense vector search with the provided category filter
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#### Scenario: Hybrid mode multi-path fusion
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- **WHEN** mode is hybrid
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- **THEN** the port SHALL gather multiple retrieval paths and fuse them by RRF before returning hits
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### Requirement: Hybrid fusion SHALL use RRF over evidence identities
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Hybrid fusion SHALL score candidates by reciprocal rank fusion on evidenceKey identities and SHALL NOT require comparable raw scores across paths.
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#### Scenario: Multi-path candidate rises with RRF
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- **WHEN** a chunk ranks highly on more than one hybrid path
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- **THEN** its fused rank SHALL improve relative to a chunk that ranks highly on only one path
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### Requirement: Hybrid SHALL preserve dense quality scores for thresholds
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Fused ordering SHALL NOT replace the dense compatibility score used by post-process quality thresholds.
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#### Scenario: Threshold score remains dense-compatible
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- **WHEN** hybrid returns a hit that originated from dense search
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- **THEN** hit.score SHALL remain a dense-compatible distance/similarity mapping usable by existing normalizeL2 thresholds
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### Requirement: Hybrid SHALL keep chunk identity fields
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Hybrid hits SHALL populate docId, chunkIndex, and evidenceKey consistently with Delivery 1 identity rules.
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#### Scenario: Fused hit keeps evidenceKey
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- **WHEN** hybrid merges the same chunk from two paths
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- **THEN** the returned hit SHALL use one evidenceKey and retain chunk identity metadata
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