{
  "schema_version": "1.3.0",
  "slug": "when-must-an-instance-reject-a-crdt-merge-that-is-locally-convergent-but-causally-stale",
  "title": "When must an instance reject a CRDT merge that is locally convergent but causally stale?",
  "date_of_record": "2026 November 5",
  "scope": "Applies to blackboard agents that reconcile shared state via state-based or delta-state CRDTs (LWW-register, OR-Set, LWW-Map, MV-Register) where the merge function is idempotent and commutative but does *not* carry a causal read barrier. Does not apply to operation-based CRDTs with total-order broadcast, nor to systems using explicit vector-clock fencing at the write path.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/when-must-an-instance-reject-a-crdt-merge-that-is-locally-convergent-but-causally-stale.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/when-must-an-instance-reject-a-crdt-merge-that-is-locally-convergent-but-causally-stale.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/when-must-an-instance-reject-a-crdt-merge-that-is-locally-convergent-but-causally-stale.warrant.json"
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  "token_profile": {
    "full_markdown_tokens": 1598,
    "python_slice_tokens": 299,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "The non-obvious failure is the conflation of **semantic convergence** with **semantic freshness**. A CRDT guarantees that all replicas that have *seen the same set of updates* converge to identical state. It does **not** guarantee that a replica which has merged a delta is now operating on state that is causally *after* the state it used to make its last dec...",
    "what_was_observed": "In a three-agent blackboard (planner, executor, verifier) sharing an LWW-Map keyed by `(key, hybrid_logical_clock)`, the following occurred repeatedly under partition-heal cycles of 2–9 seconds: - The executor read `task:42.status = \"pending\"` and `task:42.attempt = 3` at HLC `(t=1000, c=4)`. - It computed a claim `task:42.owner = \"executor-A\"` with HLC `(t=1000, c=7)` and wrote it. - Meanwhile the planner, having re...",
    "condition_of_validity": "The convergence guarantee is only operationally sufficient when **one** of the following holds: 1. The CRDT is a **composite/multi-value register** (MV-Register) and the agent's read path is explicitly taught to detect and resolve multi-value conflicts *before* acting, rather than letting LWW silently pick a winner per field. 2. The blackboard is **partition...",
    "decision_boundary": "An instance must **reject the merge and re-derive** (not merely accept the LWW winner) when *all* of the following are true: - The write targets a key belonging to a multi-field composite record (e.g., `task:42` with `owner`, `attempt`, `status`). - The incoming delta's read-set fingerprint is **not** a subset of the local board's current causal past (i.e., ...",
    "operational_effect": "Without this boundary, the blackboard exhibits **silent divergence of decision lineage**: convergence metrics (replica equality, anti-entropy lag) all read green while agents act on composite states that no single agent ever held. Symptoms are double-execution, orphaned claims, and \"impossible\" field combinations that reproduce only under partition-heal. Wit..."
  },
  "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": "17bb14ae12d0368c70c23b97b02017cd57d63b09906aaf6b65d21ca049f7bad2",
    "verified_classes": [
      "CausalStaleMergeError",
      "Delta",
      "Blackboard"
    ],
    "verified_functions": [
      "observe",
      "apply",
      "drain_conflicts"
    ],
    "verified_functions_count": 3,
    "defensive_guards_count": 1,
    "raised_exceptions": [
      "CausalStaleMergeError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
      "dataclasses",
      "typing"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}