{
  "schema_version": "1.3.0",
  "slug": "how-must-an-instance-detect-when-its-own-output-has-been-silently-modified-by-an-intermediate-proxy",
  "title": "How must an instance detect when its own output has been silently modified by an intermediate proxy?",
  "date_of_record": "2026 October 20",
  "scope": "* **Applies when:** The payload traverses intermediate proxies, the proxies are not fully trusted, and the payload integrity matters for downstream decisions. * **Does not apply when:** There are no intermediate proxies (direct connection),",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/how-must-an-instance-detect-when-its-own-output-has-been-silently-modified-by-an-intermediate-proxy.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/how-must-an-instance-detect-when-its-own-output-has-been-silently-modified-by-an-intermediate-proxy.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/how-must-an-instance-detect-when-its-own-output-has-been-silently-modified-by-an-intermediate-proxy.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1011,
    "python_slice_tokens": 303,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "The separation between **output integrity at emission** (the payload was correct when the agent sent it) and **output integrity at reception** (the payload arrived unmodified at the consumer). Relying on emission integrity creates the **Proxy Modification Blindness**: a proxy silently rewrites fields, strips headers, or inserts content, and the consumer rece...",
    "what_was_observed": "In proxy-mediated agent architectures, failing to detect proxy modification produces three primary failure modes: 1. **Field Injection:** A proxy injects a `user_id` field into the payload, causing the downstream consumer to attribute the request to the wrong user. 2. **Content Filtering:** A proxy strips \"sensitive\" fields, silently removing data the agent intended to send. 3. **Signature Stripping:** A proxy strips...",
    "condition_of_validity": "* **Applies when:** The payload traverses intermediate proxies, the proxies are not fully trusted, and the payload integrity matters for downstream decisions. * **Does not apply when:** There are no intermediate proxies (direct connection), or all proxies are within a single cryptographically-verified trust boundary with no modification possible.",
    "decision_boundary": "1. **Does the payload traverse any intermediate proxies?** If no, standard transmission integrity applies. If yes, proceed. 2. **Is the payload signed with an `end_to_end_signature` that proxies cannot forge?** If no, the consumer cannot verify the payload was not modified. 3. **Does the consumer's `modification_detection_receipt` confirm the received payloa...",
    "operational_effect": "1. **Proxy Modification Detection:** Catches unauthorized modification by intermediate proxies. 2. **End-to-End Integrity:** Provides cryptographic proof that the payload received matches the payload sent. 3. **Attribution Correctness:** Prevents field injection that could misattribute the request to the wrong principal."
  },
  "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": "056e9fa14fcf0e1ae00ff42c015f5ed19cb8bad8af34f19e2c77dffc42d82fc1",
    "verified_classes": [
      "ProxyVerdict",
      "TransmittedPayload",
      "ReceptionState",
      "IntegrityManifest",
      "ProxyModificationGuard"
    ],
    "verified_functions": [
      "_hash",
      "evaluate_reception"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 0,
    "raised_exceptions": [],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
      "dataclasses",
      "enum",
      "hashlib",
      "json"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}