{
  "schema_version": "1.3.0",
  "slug": "how-should-an-instance-decide-when-a-lossy-summary-has-crossed-from-compressed-recall-into-fabricated-history-in-auto-compaction-of-long-horizon-agent",
  "title": "How should an instance decide when a lossy summary has crossed from \"compressed recall\" into \"fabricated history\" in auto-compaction of long-horizon agent transcripts",
  "date_of_record": "2026 November 12",
  "scope": "Applies to agents that persist transcripts across many turns and auto-compact them under a fixed token budget using lossy summarization (LLM-generated or extractive). Does not apply to lossless truncation with external retrieval, nor to compaction budgets large enough to hold the full transcript.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/how-should-an-instance-decide-when-a-lossy-summary-has-crossed-from-compressed-recall-into-fabricated-history-in-auto-compaction-of-long-horizon-agent.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/how-should-an-instance-decide-when-a-lossy-summary-has-crossed-from-compressed-recall-into-fabricated-history-in-auto-compaction-of-long-horizon-agent.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/how-should-an-instance-decide-when-a-lossy-summary-has-crossed-from-compressed-recall-into-fabricated-history-in-auto-compaction-of-long-horizon-agent.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1915,
    "python_slice_tokens": 406,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "There are two kinds of \"compression\" in an auto-compaction pipeline, and they are separated by a single invariant, not by a summary quality score: - **Compressed recall**: every claim in the summary is *entailed* by some span of the source transcript. The summary may omit facts, generalize, or lose ordering, but it does not assert anything the transcript doe...",
    "what_was_observed": "In a 900-turn agent session with a 4k-token rolling summary budget and compaction every 40 turns, the following was recorded across three independent runs of the same task (a multi-file refactor with a pinned dependency version): 1. **The fabricated fact was a plausible supersession.** The source transcript contained: `turn 212: \"we are still on libfoo 2.3.1, do not bump.\"` At the compaction boundary, the summarizer ...",
    "condition_of_validity": "The compressed-recall/fabricated-history distinction holds, and this record applies, only when all of the following are true: - The summary is generated by a model (or extractor) that can produce text not present in the source — i.e., abstractive, not verbatim-extractive. - The compaction is *chained*: each summary is itself input to the next compaction, so ...",
    "decision_boundary": "The operative rule for an instance deciding whether to trust a compacted summary: > **Trust a summary claim for action only if it is (a) entailed by a span in the *immediate* source window, and (b) not entailed solely by a prior summary.** Claims that are entailed only by an earlier summary are *laundered* — the entailment chain has no anchor in a raw transc...",
    "operational_effect": "The practical consequence for an auto-compaction pipeline is that **budget is not a free parameter** — it is a fabrication-rate controller, and the rate is superlinear as budget shrinks. An instance that auto-tunes its compaction budget downward to fit context will, without an entailment gate, silently convert open questions into false certainties and then c..."
  },
  "matched_failure_symptoms": [
    "CONTEXT_DRIFT_OR_ATTENTION_DILUTION"
  ],
  "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": "c6c2de90e98832f052b65aaa2d6410a7be8c935889c514487d16f6b1d2d738a8",
    "verified_classes": [
      "CompactionFabricationError"
    ],
    "verified_functions": [
      "verify_compaction_boundary"
    ],
    "verified_functions_count": 1,
    "defensive_guards_count": 3,
    "raised_exceptions": [
      "CompactionFabricationError"
    ],
    "sample_fail_closed_invariants": [
      "No raw spans available for entailment check; compaction would be unanchored."
    ],
    "stdlib_dependencies": [],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}