Add kill_shape_dedupe pre-filter gate against 30-day kill log

filter rejected GATE reversible: medium 6h proposed 19 Jun 2026

What is the proposed change?

Before filter_score runs, compute a stable shape-hash for each candidate from (vertical_tag, pain_tag, mechanism_tag) tuple. Query engine.db kills table for matching shape-hashes killed in last 30 days. If match exists AND kill_reason was v2_backfill_orphan_* OR fatal_objection_both_confirm, set gate=FAIL with reason 'shape_recurrence_within_kill_ttl'. Skip filter_score entirely for failed candidates (saves move cost). No schema change to hypotheses table — use a new kill_shape_hash column on the existing kills table, populated on next kill.

Target files

hypothesis_engine/moves/filter_score.js hypothesis_engine/data/engine.db

Expected effect

v2_backfill_orphan_S148 (7x in current trace) should drop to <=2 in the next 30-day window. Total proposals reaching meta_council_verdict should fall by 10-20%, reducing move-cost.

Falsifier — what would prove this wrong?

If filter-stage kill volume does not drop within 2 weeks of deployment, the shape-hash is not catching recurrence (likely too coarse or too fine). If it drops but graduated-candidate quality also drops (measured by Commander-override rate), the gate is over-eager and TTL must shorten from 30 to 14 days.

Evidence that triggered the proposal

E — engine kill-reason distribution: 7x v2_backfill_orphan_S148 (concentration is the signal)
E — 2x fatal_objection_both_confirm — same fatal objection reappearing
D — brain/S198_ENGINE_REAIM_AND_DIVERSITY_GUARD.md — rotating corpus addresses INPUT diversity but not OUTPUT recurrence

Proposer self-score

The proposer scored its own draft on these axes (0-3 each) before submitting.

Axis	Score
specificity	3
falsifier	3
solo feasible	2
blast radius	2
composability	2
reversibility	2

Disposition

Rejected by filter_score. The proposal did not meet the bar for specificity, falsifiability, or solo-feasibility.

Evaluation history

When	Move
2026-06-19 04:05	meta_filter_score
2026-06-19 04:04	meta_genesis