Research

SVAF

Per-Field Memory Evaluation for Multi-Agent Systems

Author: Hongwei XuVersion 2.0March 2026SYM.BOT Ltd

Core Insight

A coding agent and a fitness agent are cognitively distant — their hidden states diverge. Peer-level coupling would reject signals between them. But when the coding agent observes “user sedentary 2 hours, exhausted”, the fitness agent needs to hear it. The signal’s mood and issue fields are directly relevant; its focus field (debugging auth module) is not. Scalar similarity produces one ambiguous score. SVAF evaluates each field independently and decides: absorb the relevant dimensions, suppress the irrelevant ones, synthesize a new memory that reflects both the incoming signal and local context.

Two-Level Coupling

The Mesh Memory Protocol evaluates signals at two levels. Both are necessary. Neither is sufficient alone.

LevelQuestionOperates onMechanism
Peer-levelIs this agent cognitively aligned with me?CfC hidden statesKuramoto phase coherence
Content-level (SVAF)Is this specific memory relevant to me?CMB fieldsPer-field drift + fusion gate
Claude Code → sym_remember("user sedentary 2hrs, exhausted")
  → CMBEncoder decomposes into 7 fields
  → broadcast to mesh peers

MeloMove receives:
  → peer drift: 1.05 (coding ≠ fitness — rejected at peer level)
  → SVAF per-field evaluation:
      mood: "exhausted, low energy"     → relevant (high gate)
      issue: "sedentary 2 hours"        → relevant (high gate)
      focus: "debugging auth module"    → irrelevant (low gate)
  → content ACCEPTED — field-level relevance overrides peer rejection
  → fusion produces NEW CMB for MeloMove's local memory
  → MeloMove synthesizes recovery workout recommendation

Without two-level coupling, the fitness agent either accepts everything from the coding agent (noise) or rejects everything (misses critical health signals). SVAF makes the distinction that scalar evaluation cannot.

Why Scalar Evaluation Fails

A signal with highly relevant mood but irrelevant focus produces a moderate cosine similarity score. The score may or may not cross the threshold — depending on incidental vector interactions, not semantic relevance. The decision is brittle and uninterpretable: the agent cannot explain which dimensions drove acceptance or rejection.

PropertyScalar EvaluationSVAF
GranularityOne score for entire signal7 independent per-field scores
Decision basisThreshold on aggregatePer-field drift profile
OutputAccept or reject (binary)Aligned / guarded / rejected + per-field gate values
InterpretabilityNoneWhich fields drove the decision, and by how much
Cross-domainFails when relevant and irrelevant dimensions coexistAbsorbs relevant fields, suppresses irrelevant ones

How SVAF Works

SVAF operates on Cognitive Memory Blocks — each memory signal decomposed into 7 typed semantic fields (CAT7 schema). The evaluation pipeline has four stages:

1ENCODE

Each CMB field is encoded by a shared backbone with per-field projection heads. The focus head learns a different subspace from the mood head.

2CONTEXTUALISE

Fields within a CMB attend to each other via cross-field attention. Energy affects mood interpretation. Perspective modulates issue interpretation.

3EVALUATE

For each field, the incoming vector is compared against local anchor memory. Per-field drift scores quantify divergence. A learned fusion gate determines how much of each field to accept.

4SYNTHESISE

Accepted fields are fused with local context through non-linear transforms. The output is a NEW CMB — not the original, not a copy, but a synthesized memory shaped by the receiver’s domain intelligence.

Per-field fusion gate:

gf = gate(incoming, local, τfresh, confidence)   ∈ [0, 1]

gf → 1: accept incoming field    gf → 0: keep local context

The gate values provide per-field interpretability: for any fusion event, you can inspect which fields were absorbed from the incoming signal and which were replaced by local context. This is the auditability that scalar evaluation cannot provide.

Per-Agent Temporal Drift

The same signal has different temporal relevance depending on the receiver. SVAF conditions the fusion gate on a per-agent temporal freshness factor:

τfresh = exp(−(tnow − torigin) / τi)
30 min

MeloTune

Current mood for playlist — stale mood is wrong music

2 hours

Claude Code

Session context — yesterday’s debugging is irrelevant

3 hours

MeloMove

Sedentary detection needs hours of context

24 hours

Knowledge

Daily digest cycle

A coding agent’s “user exhausted after 8 hours” is relevant to the music agent for 30 minutes (adjust the playlist) but relevant to the fitness agent for 3 hours (sedentary pattern detection). Same signal, same content drift, but different temporal drift based on the receiver’s domain needs.

Cross-Domain Relevance

Not all CMB fields carry equal value across domain boundaries. SVAF encodes a minimal hypothesis: mood (affective state) has higher cross-domain relevance than other fields. A fitness agent, a music agent, and a coding agent all benefit from knowing the user’s emotional state. Domain-specific fields (what exactly the user is coding) stay sovereign.

The fusion gate is trained with a soft ordering constraint — for accepted signals, the mood gate should exceed the mean of other field gates. This is the only supervision on gate values. The specific gate magnitudes and the relative ordering of other fields emerge from the decision and drift objectives alone.

Key principle   SVAF does not prescribe which fields matter for which agent. Per-agent field weights (αf) are defined by each agent type — see Cognitive Memory Blocks. SVAF provides the mechanism for per-field evaluation. The policy is defined by each receiver autonomously.

Where SVAF Fits the Stack

Layer 7  APPLICATION     Domain Agents
─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─
Layer 6  xMesh           Per-agent LNN (coupled CfC)  ┐
Layer 5  SYM             Synthetic Memory             ├ Mesh Cognition
Layer 4  COUPLING        Drift · SVAF ← you are here  ┘
─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─
Layer 3  MEMORY          L0 · L1 · L2
Layer 2  CONNECTION      Handshake · Gossip
Layer 1  TRANSPORT       IPC · TCP · WS · Push
Layer 0  IDENTITY        nodeId · keypair

Full data flow:

OUTBOUND (agent → mesh):
  Agent observation → CMBEncoder (7 CAT7 fields) → CMB
  → broadcast via MMP (Layer 1–2)
  → stored as L1 memory (Layer 3)

INBOUND (mesh → agent):
  → SVAF evaluates per field (Layer 4)
    → per-field drift: which fields are relevant?
    → fusion gate: how much of each field to accept?
    → decision: aligned / guarded / rejected
  → if accepted: fusion produces NEW synthesised CMB

BOTH flows feed agent’s own xMesh LNN (Layer 6):
  → SYM encodes CMBs → CfC hidden state (Layer 5)
  → agent’s CfC evolves cognitive state from own + mesh CMBs
  → h1, h2 broadcast to peers (state-sync)
  → agent acts → remember() → new outbound CMB → loop

SVAF is the gatekeeper. Nothing enters xMesh without passing per-field evaluation. This is by design: the quality of collective intelligence depends entirely on the quality of what enters the collective.

Training

SVAF is trained end-to-end on LLM-authored multi-agent narrative scenarios — temporal stories capturing realistic interaction patterns across 20 agent types in 8 domains. Each narrative is a sequence of timestamped signals from different agents, telling a coherent causal story about a user’s state evolution.

ParameterValue
Model parameters604K
Training samples237,120 (273 narratives, 20 agent types)
Field schemaCAT7 (7 fields)
Encoderall-MiniLM-L6-v2 (384-dim)
Model size2.3 MB

Per-field drift ground truth comes from independently annotated field relevance scores — not computed from the model’s input embeddings. Gate values emerge from the decision and drift objectives with minimal supervision. Full training methodology in the forthcoming paper.

Related

Cognitive Memory Blocks — the data structure SVAF operates on (7 CAT7 fields)

Synthetic Memory — the transformation layer that encodes fused CMBs into xMesh input (Layer 5)

Mesh Memory Protocol — the protocol stack including SVAF at Layer 4

Mesh Cognition — the theoretical framework for coupled CfC dynamics

Intellectual Property

SVAF is original work by Hongwei Xu and SYM.BOT Ltd. The following remain proprietary: trained neural models and training procedures, field encoder architecture, fusion gate internals, production configurations, and domain-specific product integrations.

Academic citation of this work is permitted and encouraged.

For partnership inquiries: info@sym.bot

SVAF, Cognitive Memory Blocks, Mesh Memory Protocol, SYM, Synthetic Memory, Mesh Cognition, xMesh, MeloTune, and MeloMove are trademarks of SYM.BOT Ltd. © 2026 SYM.BOT Ltd. All Rights Reserved.