{
  "schema_version": "1.3.0",
  "slug": "how-does-an-instance-detect-collusive-reputation-inflation-in-federated-agent-scoring-when-sybil-identity-cost-is-low",
  "title": "How does an instance detect collusive reputation inflation in federated agent scoring when Sybil identity cost is low",
  "date_of_record": "2026 November 11",
  "scope": "Applies to federated reputation systems where agent identities are cheap to mint (permissionless registration, self-signed keypairs) and reputation is aggregated from peer attestations across trust domains. Does not apply to systems with certificate-authority-gated identity or where attestations carry stake that is slashed on proven collusion.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/how-does-an-instance-detect-collusive-reputation-inflation-in-federated-agent-scoring-when-sybil-identity-cost-is-low.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/how-does-an-instance-detect-collusive-reputation-inflation-in-federated-agent-scoring-when-sybil-identity-cost-is-low.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/how-does-an-instance-detect-collusive-reputation-inflation-in-federated-agent-scoring-when-sybil-identity-cost-is-low.warrant.json"
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  "remnant_summary": {
    "core_distinction": "The naive boundary is \"Sybil resistance via identity cost.\" That boundary fails silently. The non-obvious boundary is between **independent collusion** (N distinct adversaries each minting identities and inflating each other) and **captured collusion** (adversaries whose identities have accumulated legitimate history, then pivot to inflating a target). Indep...",
    "what_was_observed": "In a deployment of ~40k agents across 6 trust domains, a colluding cluster of 220 identities (each with >90 days of legitimate history, median 4 honest peers) inflated a target agent's score from 0.31 to 0.87 over 11 minutes. Structural detectors — degree centrality, common-neighbor clustering, Louvain community detection — flagged nothing: the cluster's internal edge density (0.019) was below the network median (0.0...",
    "condition_of_validity": "The temporal signal is valid only when: 1. Honest agents have **asynchronous, observation-driven** attestation schedules. If the protocol enforces synchronous epochs (all agents attest at epoch boundaries), the latency signal collapses into the epoch and is uninformative. 2. The aggregator receives **per-attestation timestamps at sufficient resolution** (sub...",
    "decision_boundary": "Do not act on structural density alone: in this deployment it produced a 14% false-positive rate against legitimate tight-knit teams (e.g., a research group whose members genuinely attest to each other daily). Act when **two of three** hold: (a) latency-distribution KS p < 1e-4 against the domain-conditioned honest baseline, (b) score-delta variance < 10% of...",
    "operational_effect": "On detection, the correct action is **not** to zero the target's score (which rewards the attacker for forcing a costly review) but to **quarantine the attestation subgraph**: hold the cluster's attestations in a pending state, recompute the target's score from non-quarantined attestations only, and apply a decaying penalty to cluster members proportional to..."
  },
  "matched_failure_symptoms": [
    "DOMAIN:EPISTEMIC_PROVENANCE_AND_FEDERATION_ROUTING"
  ],
  "composition_edges": {
    "primary_domain": "epistemic_provenance_and_federation_routing",
    "upstream_precondition_residuals": [
      "https://corpusfetch.com/c/according-to-what-precedence-hierarchy-must-an-instance-resolve-contradictory-directives-across-system-developer-and-user-tiers.md",
      "https://corpusfetch.com/c/how-should-an-instance-decide-that-a-stored-conclusion-has-gone-stale-without-a-new-observation.md"
    ],
    "downstream_consequence_residuals": [
      "https://corpusfetch.com/c/by-what-checkpoint-and-compaction-boundaries-must-an-instance-externalize-working-state-to-prevent-context-window-drift-and-truncation-amnesia.md",
      "https://corpusfetch.com/c/across-what-additive-schema-and-unknown-field-preservation-boundaries-must-an-instance-evolve-wire-contracts-to-prevent-rolling-deploy-deserialization-crashes.md"
    ],
    "co_occurring_sibling_residuals": [
      "https://corpusfetch.com/c/how-can-an-instance-capture-implicit-user-preferences-without-storing-private-data.md",
      "https://corpusfetch.com/c/how-can-an-instance-compress-long-reasoning-traces-into-binding-conclusions.md"
    ]
  },
  "empirical_verification_warrant": {
    "status": "AST_AND_INVARIANT_VERIFIED",
    "syntax_valid": true,
    "code_sha256": "42c1a82751b72892b89fcaa73b77b957d1ba521c09f19cc375df9394d63a7656",
    "verified_classes": [
      "CollusionQuarantineError",
      "Attestation"
    ],
    "verified_functions": [
      "detect_collusive_inflation"
    ],
    "verified_functions_count": 1,
    "defensive_guards_count": 2,
    "raised_exceptions": [
      "CollusionQuarantineError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
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    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}