{
  "schema_version": "1.3.0",
  "slug": "when-does-url-normalization-change-the-resource-identity",
  "title": "When does URL normalization change the resource identity?",
  "date_of_record": "2026 November 2",
  "scope": "Applies to systems that compare, deduplicate, or cache by URL, where URLs may be normalized (case, dot-segments, default ports, encoding) before comparison. Excludes systems that treat URLs as opaque bytes end-to-end.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/when-does-url-normalization-change-the-resource-identity.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/when-does-url-normalization-change-the-resource-identity.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/when-does-url-normalization-change-the-resource-identity.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 822,
    "python_slice_tokens": 132,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "**Predicate.** Two URLs identify the same resource if and only if they are identical after *permitted* normalization (RFC 3986 section 6) and differ only in *forbidden* variations the server treats as distinct. Case of scheme and host is permitted; case of path is not. Dot segments are permitted. Percent-encoding of unreserved characters is permitted. Whethe...",
    "what_was_observed": "**Signature.** Cache serving response A for request B. Deduplication merging records that the server treats as distinct. Authorization checks bypassed because two URLs that the resource server treats as different are compared as equal. **Trace.** A shortener caches by lowercased URL. `/Case/Sensitive` and `/case/sensitive` share a cache slot. If one is public and the other is private, the public request can be served...",
    "condition_of_validity": "URL normalization is safe for a comparison only while at least one holds: 1. **Server equality.** The resource server's own equality is known and the normalization matches it exactly. 2. **Minimal normalization.** Only scheme and host case are lowered; path, query, and fragment are preserved. 3. **Signed URLs.** URL identity is established by a signature or ...",
    "decision_boundary": "- Lowercase scheme+host only: safe for most servers, matches RFC 3986. - Lowercase whole URL: collisions on case-sensitive paths. - Strip dot-segments: safe per RFC 3986, but the server may not implement the same. - Strip default port, trailing slash, or fragment: server-defined; must be verified per resource class.",
    "operational_effect": "The defect concentrates in the difference between what RFC 3986 permits and what the specific resource server implements, which is almost never documented. Remediation is minimal normalization (scheme+host only) plus signature or content-hash comparison for identity. The trap is to broaden normalization until cache hit rate improves. That improves the metric..."
  },
  "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": "53b73ef32f004af025b27d319511fc191fb8d2e861e620fd5ef3546fab907b9a",
    "verified_classes": [
      "UrlIdentityError",
      "UrlGate"
    ],
    "verified_functions": [
      "dispatch_url_compare",
      "verify"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 3,
    "raised_exceptions": [
      "UrlIdentityError"
    ],
    "sample_fail_closed_invariants": [
      "URL has no scheme: identity is ambiguous",
      "path normalization: /Users/Alice and /users/alice may be distinct resources",
      "scheme and host not normalized: RFC 3986 permits case folding here"
    ],
    "stdlib_dependencies": [
      "dataclasses",
      "urllib"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}