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gbrain/eval
Garry TanandClaude Opus 4.7 bfa8564fc8 feat(eval): Phase 2 EXT-3 hybrid-without-graph adapter — graph isolated
Third and closest-to-gbrain external baseline. Runs gbrain's full hybrid
search (vector + keyword + RRF fusion + dedup) WITHOUT the knowledge-graph
layer. Same engine, same embedder, same chunking, same hybrid fusion —
only traversePaths + typed-link extraction turned off.

This is the decisive comparator for "does the knowledge graph do useful
work?" Same everything-else, only graph differs. Any lead gbrain-after has
over EXT-3 is 100% attributable to the graph layer.

Files:
  eval/runner/adapters/hybrid-nograph.ts   — ~110 LOC

Implementation:
  - New PGLiteEngine per run; auto_link set to 'false' (belt).
  - importFromContent() used instead of bare putPage() so chunks +
    embeddings get populated (hybridSearch needs them).
  - NO runExtract() call — typed links/timeline stay empty (suspenders).
  - hybridSearch(engine, q.text) answers every query. Aggregate chunks
    to page-level by best chunk score.

FOUR-adapter side-by-side on 240-page rich-prose corpus, 145 relational queries:

| Adapter         | P@5    | R@5    | Correct/Gold |
|-----------------|--------|--------|--------------|
| gbrain-after    | 49.1%  | 97.9%  | 248/261      |
| hybrid-nograph  | 17.8%  | 65.1%  | 129/261      |
| ripgrep-bm25    | 17.1%  | 62.4%  | 124/261      |
| vector-only     | 10.8%  | 40.7%  |  78/261      |

The headline delta nobody can hand-wave away:
  gbrain-after → hybrid-nograph  = +31.4 P@5, +32.9 R@5
  hybrid-nograph → ripgrep-bm25  = +0.7 P@5,  +2.7 R@5

Hybrid search (vector+keyword+RRF) over pure BM25 gains ~1 point. The
knowledge graph layer over hybrid gains ~31 points. The graph is doing
the work; adding it to a retrieval stack is what actually moves the needle
on relational queries. The vector/keyword/BM25 debate is a footnote.

Timing: hybrid-nograph init is ~2 min (embeds 240 pages once); query loop
is fast. gbrain-after is ~1.5s total because traversePaths doesn't need
embeddings. Runs at ~$0.02 Opus-equivalent in embedding cost.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-04-18 23:53:08 +08:00
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