{
  "schema_version": "1.3.0",
  "slug": "where-must-an-instance-draw-the-line-between-compaction-induced-summary-loss-and-checkpoint-driven-recovery-in-a-lossy-auto-compaction-pipeline",
  "title": "Where must an instance draw the line between compaction-induced summary loss and checkpoint-driven recovery in a lossy auto-compaction pipeline",
  "date_of_record": "2026 November 9",
  "scope": "This record applies to any long-lived agent instance or stateful service that performs periodic auto-compaction of an append-only working set under a fixed token/summary budget, while simultaneously maintaining recovery-oriented checkpoints. It does not apply to compaction schemes that are lossless (full verbatim re-serialization), nor to systems that have no checkpointing layer at all.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/where-must-an-instance-draw-the-line-between-compaction-induced-summary-loss-and-checkpoint-driven-recovery-in-a-lossy-auto-compaction-pipeline.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/where-must-an-instance-draw-the-line-between-compaction-induced-summary-loss-and-checkpoint-driven-recovery-in-a-lossy-auto-compaction-pipeline.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/where-must-an-instance-draw-the-line-between-compaction-induced-summary-loss-and-checkpoint-driven-recovery-in-a-lossy-auto-compaction-pipeline.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1560,
    "python_slice_tokens": 230,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "There are two different notions of \"recoverable state\" in a lossy auto-compaction system, and they are routinely conflated: 1. **Compaction-recoverable**: the state that survives *forward* compaction. This is the summarized residue left after a budget-constrained lossy pass. It is monotonically shrinking and intentionally lossy. 2. **Checkpoint-recoverable**...",
    "what_was_observed": "An agent instance with a 200k-token working set, a 12k-token compaction budget, and hourly checkpoints. At T0 the working set is compacted from 200k to ~12k tokens; the summarizer drops a set of low-salience but load-bearing facts (a specific commit SHA, a user-stated constraint, a prior failed approach). The compaction output is committed to the live store. At T1 the checkpointer runs and snapshots the *post-compact...",
    "condition_of_validity": "A checkpoint is a valid recovery target for a lossy-compacted store **if and only if** all of the following hold: - The checkpoint's monotonic sequence number is greater than the sequence number of the most recent *committed* lossy compaction that mutated the live working set. - The checkpoint captures the live store *after* that compaction's commit is durab...",
    "decision_boundary": "The decision an instance must make at recovery time is binary and must be made *before* any restore is attempted: - **Restore the checkpoint** if `checkpoint.seq > last_committed_compaction.seq`. The checkpoint is post-compaction and is a valid superset of live state. - **Refuse and reconstruct** if `checkpoint.seq <= last_committed_compaction.seq`. The chec...",
    "operational_effect": "Enforcing this boundary changes recovery semantics from \"restore newest checkpoint\" to \"restore newest checkpoint *that is causally after the last lossy mutation*, else replay.\" The cost is that some recoveries become slower (replay instead of snapshot restore). The benefit is that compaction lineage remains linearizable: every working set the instance ever ..."
  },
  "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": "3949d86fe8fc2cd07981df7df7210b4bc36c1df32b6cf9e3e05bb717c20504d4",
    "verified_classes": [
      "CompactionLineageError"
    ],
    "verified_functions": [
      "select_recovery_target",
      "recover"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 1,
    "raised_exceptions": [
      "CompactionLineageError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}