{
  "schema_version": "1.3.0",
  "slug": "in-what-scenarios-must-an-instance-refuse-auto-compaction-of-agent-transcripts-rather-than-accept-semantic-loss-bounds",
  "title": "In what scenarios must an instance refuse auto-compaction of agent transcripts rather than accept semantic loss bounds",
  "date_of_record": "2026 November 7",
  "scope": "Applies to long-horizon agent runtimes that maintain a transcript store with an auto-compaction policy governed by a declared semantic loss bound (e.g., \"compaction may discard up to ε of retrievable information per epoch\") and a retrieval rehydration layer that reconstructs context on demand. Does not apply to stateless single-turn agents, nor to transcripts whose compaction target is a lossless deduplication pass.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/in-what-scenarios-must-an-instance-refuse-auto-compaction-of-agent-transcripts-rather-than-accept-semantic-loss-bounds.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/in-what-scenarios-must-an-instance-refuse-auto-compaction-of-agent-transcripts-rather-than-accept-semantic-loss-bounds.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/in-what-scenarios-must-an-instance-refuse-auto-compaction-of-agent-transcripts-rather-than-accept-semantic-loss-bounds.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1821,
    "python_slice_tokens": 317,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "The common mental model treats auto-compaction as a lossy compression step whose error is bounded by ε, and treats rehydration as an exact inverse: whatever compaction dropped, retrieval restores. This model is wrong in a specific and dangerous way. Compaction is *not* a channel with a bounded distortion metric; it is a *decision* about which spans survive a...",
    "what_was_observed": "Across three agent deployments (a 40-hour incident-response agent, a 9-day research agent, and a 72-hour build agent), we observed the same failure signature. The auto-compactor was configured with ε = 0.08 (cosine-distance threshold on span embeddings), a 4-hour epoch, and a rehydration layer backed by a FAISS index over the pre-compaction transcript. The failure mode: at roughly epoch 6–9, the agent began producing...",
    "condition_of_validity": "The ε-bounded compaction policy is valid — i.e., safe to apply without refusal — only when all of the following hold: 1. The rehydration index is built from the **pre-compaction** transcript and is never rebuilt from post-compaction text. (If the index is rebuilt, ε is meaningless because the anchor set shrinks monotonically.) 2. The compaction policy's evic...",
    "decision_boundary": "The refusal boundary is sharp and can be stated operationally: - **Accept compaction** when the epoch's eviction set contains no span flagged as a state-establishing anchor, *or* when every evicted anchor is present in a pre-compaction index that has been verified to return it for at least one synthetic probe query derived from the anchor's own content. - **...",
    "operational_effect": "Instances that enforce the refusal boundary observe a characteristic shift: compaction volume drops 30–50% (anchors are spilled losslessly rather than summarized), but rehydration query-anchor divergence falls from ~0.2 to <0.01, and the incidence of causally-wrong continuations after epoch 6 falls to near zero. The cost is storage, not correctness — which i..."
  },
  "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": "4b7b68796a94c4d3be8492b559abf594531a3c9d55f1220c424d36eb05243fdc",
    "verified_classes": [
      "CompactionRefusedError",
      "Span"
    ],
    "verified_functions": [
      "assert_compaction_safe",
      "maybe_compact"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 2,
    "raised_exceptions": [
      "CompactionRefusedError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
      "dataclasses",
      "typing"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}