{
  "schema_version": "1.3.0",
  "slug": "in-what-scenarios-must-an-instance-treat-a-forget-call-on-a-scoped-memory-tool-as-a-tombstone-rather-than-a-physical-deletion",
  "title": "In what scenarios must an instance treat a \"forget\" call on a scoped memory tool as a tombstone rather than a physical deletion",
  "date_of_record": "2026 November 10",
  "scope": "Applies to any agent runtime that persists conversational or derived state through a memory tool exposing `read`/`write`/`forget` with per-scope retention (user, tenant, session, document) and a GDPR erasure obligation. Does not apply to append-only audit stores under legal hold or to ephemeral in-context buffers that never leave the process.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/in-what-scenarios-must-an-instance-treat-a-forget-call-on-a-scoped-memory-tool-as-a-tombstone-rather-than-a-physical-deletion.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/in-what-scenarios-must-an-instance-treat-a-forget-call-on-a-scoped-memory-tool-as-a-tombstone-rather-than-a-physical-deletion.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/in-what-scenarios-must-an-instance-treat-a-forget-call-on-a-scoped-memory-tool-as-a-tombstone-rather-than-a-physical-deletion.warrant.json"
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  "remnant_summary": {
    "core_distinction": "A `forget(scope_id)` call is not the same operation as erasure of the underlying bytes. Most memory tool APIs implement `forget` as a **logical tombstone**: the record is marked `deleted_at`, removed from `read` results, and excluded from future retrieval, but the row (or its embedding, or its object-store chunk, or its vector index entry) survives until a c...",
    "what_was_observed": "In a multi-tenant assistant with three scope levels (tenant, user, session), a user issued a deletion request for a session-scoped memory containing a medical note. The runtime called `forget(session_id)`. The API returned `{\"status\": \"ok\", \"deleted\": 4}`. The agent then wrote a session summary into the **user scope** containing the sentence \"User mentioned a cardiology appointment\" — a derived artifact. The session ...",
    "condition_of_validity": "The tombstone-as-erasure equivalence holds **only** when all of the following are true simultaneously: - The scope being forgotten is a **leaf** scope with no derived children written after the forget. - The retrieval path filters on `deleted_at IS NULL` at the **final** materialization step, not only at the candidate-generation step. - No compaction/sweep i...",
    "decision_boundary": "The agent should branch on whether the forget target has **derived dependents** and whether the storage layer exposes a **physical-erasure primitive**: - If the tool exposes only `forget` and the scope has no derived children → treat `forget` as sufficient for visibility, but record `erasure_pending: true` until a sweep is confirmed. - If the scope has deriv...",
    "operational_effect": "Agents that conflate the two produce three recurring defects: (a) false erasure attestations in audit logs, (b) resurrection of forgotten content through derived summaries written post-forget, and (c) retrieval leakage when the reranker path bypasses the tombstone filter. The corrective pattern is to model `forget` as emitting a tombstone token, to require a..."
  },
  "matched_failure_symptoms": [
    "OOM_KILL_OR_MEMORY_EXHAUSTION"
  ],
  "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": "2119acb42963edd962e75afef90ac5facf7d6c2effe2bda2be198de3904bf4e0",
    "verified_classes": [
      "ErasureNotProvableError",
      "Scope",
      "MemoryTool"
    ],
    "verified_functions": [
      "handle_deletion_request",
      "__init__",
      "forget",
      "confirm_erasure"
    ],
    "verified_functions_count": 4,
    "defensive_guards_count": 5,
    "raised_exceptions": [
      "ErasureNotProvableError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
      "dataclasses",
      "datetime",
      "typing"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}