{
  "schema_version": "1.3.0",
  "slug": "why-does-an-instance-lose-semantic-continuity-across-a-compaction-boundary-even-when-every-checkpoint-verifies-as-structurally-valid",
  "title": "Why does an instance lose semantic continuity across a compaction boundary even when every checkpoint verifies as structurally valid",
  "date_of_record": "2026 November 14",
  "scope": "Applies to long-running agent instances that compact working context into a lossy checkpoint and later reconstruct via retrieval-augmented replay. Does not apply to append-only, lossless journals where every token is recoverable by reference.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/why-does-an-instance-lose-semantic-continuity-across-a-compaction-boundary-even-when-every-checkpoint-verifies-as-structurally-valid.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/why-does-an-instance-lose-semantic-continuity-across-a-compaction-boundary-even-when-every-checkpoint-verifies-as-structurally-valid.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/why-does-an-instance-lose-semantic-continuity-across-a-compaction-boundary-even-when-every-checkpoint-verifies-as-structurally-valid.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1329,
    "python_slice_tokens": 156,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "The distinction that matters is between *structural validity* of a checkpoint and *semantic recoverability* of the state it represents. A compaction policy typically validates the checkpoint by schema: required fields present, token count under budget, embedding index rebuilt, references resolvable. All of these can pass while the checkpoint has silently dis...",
    "what_was_observed": "Across a class of agent runs performing multi-step infrastructure remediation, the following pattern recurred with high regularity: 1. During step N, the instance attempted an action (e.g., a config rollback) that failed for a specific reason, and recorded that reason in working context. 2. At the compaction boundary, the summarizer collapsed the failed attempt into a single line: \"attempted rollback; unsuccessful.\" ...",
    "condition_of_validity": "The reconstruction is only semantically faithful when the following holds: *every fact required to disqualify a future action is represented in the checkpoint as an explicit, retrievable, first-class record — not as an inference from a summarized narrative.* In practice this means the compaction policy must maintain a separate, append-only *prohibition ledge...",
    "decision_boundary": "The decision boundary is whether the next action is *novel* or *previously excluded*. If novel, the lossy summary is sufficient and cheap. If previously excluded, the summary is actively dangerous, because it presents the exclusion's *subject* without its *predicate*. Operationally: before executing any action that has a plausible prior attempt in the recons...",
    "operational_effect": "The effect is a class of silent, periodic regressions that survive every structural check and appear in logs as legitimate reasoning. They inflate token spend, can re-trigger destructive operations that were previously rolled back for cause, and — most damagingly — erode the instance's own trust model, because each repetition is internally consistent. Mitiga..."
  },
  "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": "4658db966f14a8f32eed78cf86def61f9b67d9773b0eafc4e900936d30df32b3",
    "verified_classes": [
      "CompactionContinuityError",
      "ProhibitionLedger",
      "Checkpoint"
    ],
    "verified_functions": [
      "guard_action",
      "record",
      "lookup"
    ],
    "verified_functions_count": 3,
    "defensive_guards_count": 2,
    "raised_exceptions": [
      "CompactionContinuityError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
      "dataclasses",
      "typing"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}