{
  "schema_version": "1.3.0",
  "slug": "why-does-an-instance-of-a-speculative-branch-replay-diverge-from-the-recorded-trace-when-the-branch-was-marked-committed-but-its-parent-agent-had-alre",
  "title": "Why does an instance of a speculative branch replay diverge from the recorded trace when the branch was marked \"committed\" but its parent agent had already been garbage-collected?",
  "date_of_record": "2026 November 10",
  "scope": "Applies to deterministic replay of multi-agent speculative execution graphs where branch commits are recorded as logical events but parent agent state is subject to reference-counted or TTL-based reclamation. Does not apply to systems that retain full lineage snapshots for the entire replay window, nor to single-agent speculative decoding where no cross-agent parent reference exists.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/why-does-an-instance-of-a-speculative-branch-replay-diverge-from-the-recorded-trace-when-the-branch-was-marked-committed-but-its-parent-agent-had-alre.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/why-does-an-instance-of-a-speculative-branch-replay-diverge-from-the-recorded-trace-when-the-branch-was-marked-committed-but-its-parent-agent-had-alre.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/why-does-an-instance-of-a-speculative-branch-replay-diverge-from-the-recorded-trace-when-the-branch-was-marked-committed-but-its-parent-agent-had-alre.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1530,
    "python_slice_tokens": 206,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "The failure is not \"replay diverges because nondeterminism leaked in.\" It is a **commit-ordering versus reclamation-ordering** mismatch. A branch can be marked `committed` in the event log before (or concurrently with) the parent agent's state being reclaimed, because commit is a *logical* property of the branch while reclamation is a *physical* property of ...",
    "what_was_observed": "During post-incident analysis of a 7-agent speculative rollout (planner → 4 parallel executors → 2 synthesizers), replay of a failed run produced a synthesis branch that re-executed \"successfully\" and emitted a plausible output, whereas the original run had emitted a refusal. Investigation showed: - The synthesis branch was recorded as `committed` at logical time T+410ms. - Its parent executor agent's state was recla...",
    "condition_of_validity": "The invariant \"a committed branch's recorded inputs fully determine its replay\" holds **only if** the replayer treats recorded inputs as authoritative and never re-derives them from parent state. This is violated whenever: 1. The replayer reconstructs context by walking the parent chain rather than reading the branch's frozen input snapshot, **and** 2. Paren...",
    "decision_boundary": "The operational choice is: **freeze branch inputs at commit and treat them as the sole replay authority, or pin parent state and accept the memory cost.** There is no third option that preserves both aggressive reclamation and faithful replay, because the parent context is not recoverable from the branch record once the parent is gone — the branch record onl...",
    "operational_effect": "Forensic analyses that replay the full speculative tree will, under this condition, produce **false-negative incident attributions**: the replayed run succeeds where the original failed, and the analyst concludes the original failure was transient or environmental rather than a genuine constraint violation. The synthesis branch's refusal is re-attributed 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": "65d810252ffdb304a51ec7be66086409993c52ac832b2aea88f6dd7351e966d8",
    "verified_classes": [
      "UnreplayableBranchError"
    ],
    "verified_functions": [
      "replay_branch",
      "_execute_with_inputs"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 1,
    "raised_exceptions": [
      "UnreplayableBranchError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}