Supersession demotion too weak: absolute penalty insufficient when old memory has higher raw cosine similarity

[Liorrr]

Problem

The supersession demotion is absolute (supersedes_demotion = 0.15). When a superseded (OLD) memory has higher raw cosine similarity to a query than the NEW memory, the fixed 0.15 penalty is insufficient to flip the ranking.

Evidence — NR benchmark: 0/3 (0%)

NR-1 'Where does Sam work now?': Shopify/payments (OLD) still ranks #2 despite supersession edge to Stripe/billing (NEW). Old memory contains 'work at' literally → higher cosine sim for work-related queries.

NR-3 'What editor does Sam use?' PASSES because Neovim (shorter, direct) gets higher raw sim than VS Code + Copilot entry.

Root cause: score = raw_sim - 0.15 for superseded memories. If raw_sim_old - raw_sim_new > 0.15, the OLD memory still wins.

Fix Directions

• Relative demotion: score *= 0.6 instead of score -= 0.15 (XS, recommended short-term)
• Aggressive demotion: increase from 0.15 to 0.40 (XS)
• Entity-boosted scoring at query time (M, KS73 entity system enables this)
• KS75 store-time contradiction detection (L, real fix)

Discovered during KS73 overnight benchmark session (2026-04-08). Benchmark: benchmark_negative_recall.