{
  "schema_version": "1.3.0",
  "slug": "how-should-an-instance-distinguish-checkpoint-staleness-from-summary-space-saturation-in-hierarchical-agent-compaction",
  "title": "How should an instance distinguish checkpoint staleness from summary-space saturation in hierarchical agent compaction",
  "date_of_record": "2026 November 13",
  "scope": "Applies to long-horizon agents that maintain a hierarchy of summarization checkpoints (leaf → mid → root) and run auto-compaction triggered by token budget, turn count, or event count. Does not apply to single-level truncation schemes, retrieval-augmented memory without summarization, or agents whose root summary is regenerated from raw transcript on every compaction.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/how-should-an-instance-distinguish-checkpoint-staleness-from-summary-space-saturation-in-hierarchical-agent-compaction.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/how-should-an-instance-distinguish-checkpoint-staleness-from-summary-space-saturation-in-hierarchical-agent-compaction.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/how-should-an-instance-distinguish-checkpoint-staleness-from-summary-space-saturation-in-hierarchical-agent-compaction.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1881,
    "python_slice_tokens": 332,
    "warrant_slice_tokens": 220
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  "remnant_summary": {
    "core_distinction": "Auto-compaction failures in hierarchical summarizers are routinely diagnosed as *checkpoint staleness* — the belief that a parent checkpoint was written before the most recent leaf events and therefore lags reality. The corrective action is then to force a root regeneration, which is expensive and often destabilizing. The non-obvious boundary is that a large...",
    "what_was_observed": "In a 40-hour agent run with a three-level hierarchy (leaf summaries every 8 turns, mid every 64 turns, root every 512 turns), the following sequence recurred four times: 1. Root checkpoint queried for a constraint (\"the export must exclude PII columns\") stated at turn 30 and reinforced at turns 210 and 480. 2. Root summary omitted the constraint. Mid-level summaries at turns 256 and 448 *did* contain it, each in slig...",
    "condition_of_validity": "The staleness diagnosis is valid only when: - Child checkpoints changed since the parent was written **and** the parent's retained-proposition set is a strict subset of the union of child proposition sets (i.e., the parent is missing *only* things added after its write time). - Regenerating the parent against current children strictly increases retained prop...",
    "decision_boundary": "The operational rule: - **Regenerate** the parent when: retained-proposition count after a trial regeneration exceeds the current count by more than the churn noise floor (observed ~15% cardinality variance), *and* parent budget ≥ child joint entropy estimate. - **Rebalance** (split/raise budget) when: trial regeneration yields cardinality within noise of cu...",
    "operational_effect": "Agents that conflate the two modes exhibit a characteristic pathology: repeated root regeneration, each producing a plausible-looking summary, each losing a different constraint, with the agent's behavior oscillating between \"remembers the PII rule but forgets the rate limit\" and vice versa. Downstream, this reads as inconsistency and erodes operator trust 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": "6bc0f9ee2ecb054ce2d46233da9fa4f0566b1f340d9f92d8fe0379f5097bdb84",
    "verified_classes": [
      "CompactionInvariantError",
      "Checkpoint"
    ],
    "verified_functions": [
      "classify_regeneration",
      "remediate"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 6,
    "raised_exceptions": [
      "CompactionInvariantError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
      "dataclasses"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}