{
  "schema_version": "1.3.0",
  "slug": "what-structural-signals-indicate-a-tombstone-has-become-a-ghost-distinguishing-lawful-forgetting-completion-from-retention-policy-shadow-state-in-read",
  "title": "What structural signals indicate a tombstone has become a ghost: distinguishing lawful-forgetting completion from retention-policy shadow state in read/write/forget memory APIs",
  "date_of_record": "2026 November 11",
  "scope": "Applies to memory tool APIs exposing `read`/`write`/`forget` with retention TTLs, redaction transforms, and lawful-forgetting (GDPR/CCPA-style erasure) semantics, where a forget request may be satisfied by tombstoning a record rather than physically purging its bytes. Does not apply to systems with synchronous hard-delete guarantees or to append-only ledgers where erasure is expressed as cryptographic shredding with verifiable key destruction.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/what-structural-signals-indicate-a-tombstone-has-become-a-ghost-distinguishing-lawful-forgetting-completion-from-retention-policy-shadow-state-in-read.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/what-structural-signals-indicate-a-tombstone-has-become-a-ghost-distinguishing-lawful-forgetting-completion-from-retention-policy-shadow-state-in-read.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/what-structural-signals-indicate-a-tombstone-has-become-a-ghost-distinguishing-lawful-forgetting-completion-from-retention-policy-shadow-state-in-read.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1784,
    "python_slice_tokens": 313,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "A `forget` operation has two distinct terminal states that the API surface almost never distinguishes: **completed erasure** and **shadow retention**. In the shadow state, the record is no longer returned by `read` and is no longer addressable by `write`, yet the underlying payload persists in at least one of: a tombstone row carrying the original value, a r...",
    "what_was_observed": "Across a class of memory backends, the following pattern recurs. A `forget(record_id)` call returns `{\"status\": \"forgotten\", \"tombstone_id\": ...}`. A subsequent `read(record_id)` returns `404` or `null`. The agent concludes erasure succeeded. However: 1. **Tombstone payload residue.** The tombstone row stores `original_value` or a `redaction_preimage` field so that \"undo\" and differential sync can function. This is a...",
    "condition_of_validity": "The distinction holds — tombstone-as-completion is a false signal — under all of the following: - The store implements forget via tombstoning, redaction-transform, or TTL-shadow rather than synchronous physical purge of all replicas and backups. - The retention policy's erasure scope does not explicitly and verifiably exclude tombstone payloads, redaction pr...",
    "decision_boundary": "An agent must treat a forget as **incomplete** and enter a verification path when any of the following structural signals is present: - The forget response contains a `tombstone_id` but no `destroyed_at` / `destruction_receipt` / `purge_attestation` field referencing the specific record version. - The record's audit trail shows a `redaction` event without a ...",
    "operational_effect": "The practical consequence is a mandatory post-forget verification step and a vocabulary discipline. Agents that skip verification will, at some rate, report lawful erasure while the data remains recoverable — a silent correctness failure that only surfaces under audit. The operational rule is: **never equate `read → null` with erasure; equate it with non-vis..."
  },
  "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": "ae3d822e0af6723e892977afea42e665f322b33847a278c2302ee63e27469e98",
    "verified_classes": [
      "ForgetVerificationError"
    ],
    "verified_functions": [
      "assert_lawful_erasure"
    ],
    "verified_functions_count": 1,
    "defensive_guards_count": 5,
    "raised_exceptions": [
      "ForgetVerificationError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}