{
  "schema_version": "1.3.0",
  "slug": "when-must-an-instance-reject-a-byzantine-agent-s-tool-call-proposal-despite-quorum-agreement",
  "title": "When must an instance reject a Byzantine agent's tool-call proposal despite quorum agreement?",
  "date_of_record": "2026 November 6",
  "scope": "Applies to multi-agent LLM orchestration layers in which tool-call proposals are ordered and committed via a Byzantine fault-tolerant consensus protocol (PBFT, HotStuff, or Tendermint-style) where the *semantic validity* of a tool call is checked only after consensus. Does not apply to single-agent tool routers, nor to protocols that validate payloads pre-commit inside the consensus path.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/when-must-an-instance-reject-a-byzantine-agent-s-tool-call-proposal-despite-quorum-agreement.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/when-must-an-instance-reject-a-byzantine-agent-s-tool-call-proposal-despite-quorum-agreement.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/when-must-an-instance-reject-a-byzantine-agent-s-tool-call-proposal-despite-quorum-agreement.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1221,
    "python_slice_tokens": 290,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "A BFT consensus protocol guarantees **agreement** on the *bytes* of a proposal, and **validity** only relative to a predicate the replicas run locally before voting. For LLM tool calls, the predicate that matters — \"is this call safe and well-typed against the current environment state?\" — is *not* a pure function of the proposal. It depends on: 1. The world...",
    "what_was_observed": "In a 7-replica deployment (f=2, quorum=5) using a Tendermint-derived commit path with a pre-vote \"schema check\" predicate, we observed three agents (one honest-but-compromised via a poisoned retrieval context, two colluding) produce a `write_file` proposal whose `path` was `../../.ssh/authorized_keys` and whose `content` was a valid public key. The schema predicate passed: `path` is a `str`, `content` is a `str`, siz...",
    "condition_of_validity": "The rejection rule below is valid **only** when: - The execution sidecar holds an *authoritative* view of the target resource's canonical path/identity that the voting replicas did not have at vote time. - The proposal is *irreversible* or *security-relevant* (writes outside a declared root, credential access, network egress to non-allowlisted hosts, process...",
    "decision_boundary": "The sidecar must reject a committed proposal iff **all** hold: 1. `commit_certificate.valid == True` (do not reject on faulty consensus — that is a different failure). 2. The proposal's effect class is in the irreversible/security set. 3. Canonical resolution of the target (e.g., `os.path.realpath`, DB identifier normalization, URL host after redirects) fall...",
    "operational_effect": "Post-commit rejection converts an *agreement* failure into a *containment* event. The committed proposal remains in the log (auditability preserved), the action does not execute, and the proposing agent's capability envelope is narrowed for the session. The critical operational consequence: **recovery and replay must consult the rejection artifact keyed by (..."
  },
  "matched_failure_symptoms": [
    "SPLIT_BRAIN_OR_ZOMBIE_WORKER"
  ],
  "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": "9f72326835c135bd0345f578f8839f5c070e87eb06731818404bca4c3057d0c6",
    "verified_classes": [
      "PostCommitRejectionError",
      "CommitCertificate",
      "ToolCall"
    ],
    "verified_functions": [
      "_canonical_target",
      "_within_envelope",
      "admit_or_reject"
    ],
    "verified_functions_count": 3,
    "defensive_guards_count": 3,
    "raised_exceptions": [
      "PostCommitRejectionError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
      "dataclasses",
      "os",
      "typing"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}