{
  "schema_version": "1.3.0",
  "slug": "what-happens-when-an-instance-replays-a-trace-whose-side-effect-ordering-was-never-serialized",
  "title": "What happens when an instance replays a trace whose side-effect ordering was never serialized",
  "date_of_record": "2026 November 11",
  "scope": "Applies to deterministic replay of agent traces where the trace records tool invocations, model calls, and their results, but does not record the causal serialization order between concurrent side-effecting operations. Does not apply to traces captured under a single-threaded executor with a global lock, nor to traces that include an explicit happens-before vector per event.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/what-happens-when-an-instance-replays-a-trace-whose-side-effect-ordering-was-never-serialized.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/what-happens-when-an-instance-replays-a-trace-whose-side-effect-ordering-was-never-serialized.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/what-happens-when-an-instance-replays-a-trace-whose-side-effect-ordering-was-never-serialized.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1379,
    "python_slice_tokens": 345,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "A trace is *replayable* when every event in it can be reconstructed from recorded inputs. A trace is *deterministically replayable* only when the reconstruction preserves the *order* in which observable effects were committed. These are not the same property. Most agent trace formats record what was called and what came back; almost none record the interleav...",
    "what_was_observed": "During reconstruction of a multi-tool agent run, the replay engine re-executed a recorded plan: a write to a scratch file, a read of the same file, and a compensating delete. In the original run, the read observed the written content because the write's commit preceded the read's dispatch. On replay, the executor's scheduler dispatched the read and the delete concurrently against a thread pool; the read landed after ...",
    "condition_of_validity": "Deterministic replay is valid only when, for every pair of events whose effects are *observably dependent* (one reads what the other writes, one cancels the other, one consumes a resource the other releases), the trace encodes a total order over that pair, and the replay executor honors it. Where the trace encodes only partial order — or none — replay is val...",
    "decision_boundary": "Before trusting a replay for forensics, classify each event pair: - **Order recorded, executor honors it** → replay is evidentiary. Proceed. - **Order recorded, executor ignores it** → replay is invalid; the executor is at fault, not the trace. Fix the executor before drawing conclusions. - **Order absent, events provably independent** (no shared resource, n...",
    "operational_effect": "Teams that treat replay success as evidence of reconstruction accuracy will, in the dependent-and-unordered case, produce incident reports that confidently invert cause and effect. The failure is silent because the replay engine's re-derived results are internally consistent — they are just not the results that occurred. The mitigation is to record a monoton..."
  },
  "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": "050effd5a17837ee2f9b58aacd4edb0577e1f1313885174ab805c1034433bc35",
    "verified_classes": [
      "OrderIncompleteTraceError",
      "TraceEvent"
    ],
    "verified_functions": [
      "assert_replay_is_evidentiary",
      "replay",
      "__init__"
    ],
    "verified_functions_count": 3,
    "defensive_guards_count": 2,
    "raised_exceptions": [
      "OrderIncompleteTraceError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}