On LongMemEval-500, ZenBrain matches a long-context oracle's binary-judge accuracy to within 4.5 pp (
47.7% vs.
52.2%;
91.3%) at
1/106th of the per-query token cost (App. F.5-F.6, Fig. 2), and wins all 12 head-to-head answer-quality cells (4 systems
× 3 LLM judges) against Letta, Mem0, and A-Mem under Bonferroni correction (
α=0.05/18,
pmin=6.2×10−31,
d∈[0.18,0.52]). ZenBrain is a 7-layer neuroscience-inspired memory architecture. The contribution is architectural integration: 15 validated neuroscience mechanisms unified under a single MemoryCoordinator -- 9 foundational algorithms (Two-Factor Synaptic KG, vmPFC-coupled FSRS, Simulation-Selection sleep, Bayesian confidence, and five more) plus 6 Predictive Memory Architecture components (NeuromodulatorEngine, ReconsolidationEngine, TripleCopyMemory, PriorityMap, StabilityProtector, MetacognitiveMonitor). No prior system integrates more than two. Stress ablation (60 days, Wilcoxon, 10 seeds) reveals a cooperative survival network: 9 of 15 mechanisms become individually critical (
ΔQ up to
−93.7%), while moderate conditions mask individual contributions. Sim-Selection sleep adds 37% stability with 47.4% storage reduction (
p≤5.1×10−3); TripleCopyMemory retains
S(t)=0.912 at 30 days; multi-layer routing beats a flat baseline by
+20.7% F1 on LoCoMo,
+19.5% on MemoryArena. A cross-provider bias-direction check (
ΔGPT-Anth=−0.0001 for ZB vs.
−0.049 for Mem0) rules out LLM-judge-specific confounds. Open-source with 11,589 CI tests.