{
  "schema_version": "1.3.0",
  "slug": "what-happens-when-an-instance-downgrades-a-trusted-provenance-tier-mid-generation-taint-boundary-violation-in-provenance-tracked-rag",
  "title": "What happens when an instance downgrades a trusted provenance tier mid-generation: taint-boundary violation in provenance-tracked RAG",
  "date_of_record": "2026 November 14",
  "scope": "Applies to retrieval-augmented generation pipelines that attach per-chunk provenance trust tiers (e.g., `signed`, `curated`, `unverified`, `tainted`) and enforce taint-aware policies at retrieval time. Does not apply to systems that re-validate provenance at every token-emission step, nor to stateless single-shot RAG with no tier metadata.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/what-happens-when-an-instance-downgrades-a-trusted-provenance-tier-mid-generation-taint-boundary-violation-in-provenance-tracked-rag.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/what-happens-when-an-instance-downgrades-a-trusted-provenance-tier-mid-generation-taint-boundary-violation-in-provenance-tracked-rag.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/what-happens-when-an-instance-downgrades-a-trusted-provenance-tier-mid-generation-taint-boundary-violation-in-provenance-tracked-rag.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1630,
    "python_slice_tokens": 336,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "The non-obvious boundary is between **retrieval-time taint enforcement** and **generation-time taint enforcement**. Most provenance-tracked RAG systems enforce the trust-tier policy when assembling the context window: a chunk whose tier is below the caller's minimum threshold is dropped before the prompt is built. This is correct but insufficient. The failur...",
    "what_was_observed": "In a pipeline where chunks carried signed provenance manifests with a 300-second signature TTL, a revocation sweep marked a batch of documents `tainted` roughly 40 seconds into a long-context generation (the generation ran ~90 seconds due to a 200k-token context). The retrieval gate had admitted those chunks at t=0 when they were `curated` and validly signed. At t=40s the signatures were revoked. The generation compl...",
    "condition_of_validity": "The taint-aware guarantee holds only under the conjunction: 1. **Provenance is immutable for the lifetime of the context window.** Signatures do not expire, revocations do not land, and tiers do not change between admission and emission. 2. **The output attestation is derived from a lookup at emission time, not from the admission snapshot.** If the envelope ...",
    "decision_boundary": "The decision is whether to **re-validate at emission** (continuous enforcement) or to **bound generation duration below the provenance-change interval** (admission-only enforcement with a hard time budget). Choose continuous re-validation when: provenance can change asynchronously (revocation lists, TTLs, retroactive taint), generations are long, or outputs ...",
    "operational_effect": "The practical effect is that **tier attestations become untrustworthy exactly when they matter most**: long, expensive, high-stakes generations that outlive their provenance. Downstream consumers cannot distinguish a `curated` stamp that was true at emission from one that was true at admission. The remediation that works is to make the attestation a function..."
  },
  "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": "8dbd3d0ee7324380c90189f3400697d83134714d1c20af3c858f1804d184015b",
    "verified_classes": [
      "Tier",
      "TaintBoundaryViolation",
      "ContextSlot"
    ],
    "verified_functions": [
      "resolve_emission_tier",
      "stamp_output"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 2,
    "raised_exceptions": [
      "TaintBoundaryViolation"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
      "__future__",
      "dataclasses",
      "enum",
      "typing"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}