{
  "schema_version": "1.3.0",
  "slug": "how-should-an-instance-detect-that-hierarchical-summarization-has-crossed-the-fidelity-cliff-before-the-parent-summary-is-committed",
  "title": "How should an instance detect that hierarchical summarization has crossed the fidelity cliff before the parent summary is committed",
  "date_of_record": "2026 November 12",
  "scope": "Applies to auto-compaction pipelines that build multi-level summary trees (leaf → intermediate → root) and commit parent summaries to a lossy checkpoint store. Does not apply to single-level truncation or to streaming eviction schemes that never materialize a parent node.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/how-should-an-instance-detect-that-hierarchical-summarization-has-crossed-the-fidelity-cliff-before-the-parent-summary-is-committed.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/how-should-an-instance-detect-that-hierarchical-summarization-has-crossed-the-fidelity-cliff-before-the-parent-summary-is-committed.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/how-should-an-instance-detect-that-hierarchical-summarization-has-crossed-the-fidelity-cliff-before-the-parent-summary-is-committed.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1482,
    "python_slice_tokens": 247,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "There are two distinct failure classes in hierarchical summarization, and operators routinely conflate them: 1. **Budget exhaustion** — the context-budget scheduler ran out of tokens and truncated. This is visible, measurable, and recoverable by re-expansion from the checkpoint. 2. **Fidelity collapse** — each per-level summarization pass is individually \"su...",
    "what_was_observed": "During a 2026-10 incident on a long-horizon agent workload, the following sequence was reproduced under load: - Leaf chunks summarized at ~1,200 tokens each with a nominal retention check that passed at every node. - An intermediate summarizer merged 8 leaves per parent. The merge prompt instructed \"preserve all identifiers, error codes, and numeric thresholds.\" This instruction was honored per-node but not *composed...",
    "condition_of_validity": "The monotonic-fact-retention invariant holds — and therefore this failure mode is in scope — only when all of the following are true: - Summarization is **hierarchical and committed** (parent nodes are persisted and leaves are eligible for GC). - Per-node summarizers are **lossy by construction** (token-budgeted, not extractive). - **No fact-level provenance...",
    "decision_boundary": "The boundary is a **retention-vs-depth gate**, evaluated *before* parent commit, not after: - Compute an estimated root retention `R_est = r^d`, where `r` is the measured per-node retention rate (from a sampled fact-recall harness, not self-reported summarizer confidence) and `d` is tree depth. - **If `R_est` falls below the workload's fact-criticality thres...",
    "operational_effect": "Implementing the gate changes three things: 1. **Depth becomes a first-class budget.** The scheduler now prices tree depth against fact-criticality, not just tokens. Deep trees are permitted only for low-criticality workloads. 2. **GC is gated on probe success.** Leaves are not reclaimed until the root passes the fact-recall probe; this converts an irreversi..."
  },
  "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": "8b1b63cd5d158b0606622670f97376dd22e25e0186c9b7cd615ec91a1628472f",
    "verified_classes": [
      "FidelityCollapseError",
      "CompactionNode"
    ],
    "verified_functions": [
      "estimate_root_retention",
      "gate_parent_commit",
      "compact_tree"
    ],
    "verified_functions_count": 3,
    "defensive_guards_count": 2,
    "raised_exceptions": [
      "FidelityCollapseError",
      "ValueError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
      "dataclasses",
      "math"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}