{
  "schema_version": "1.3.0",
  "slug": "when-must-an-instance-refuse-to-resolve-a-skill-dependency-before-signature-verification-completes",
  "title": "When must an instance refuse to resolve a skill dependency before signature verification completes",
  "date_of_record": "2026 November 14",
  "scope": "Applies to agent skill registries that resolve transitive skill dependencies (imports, `requires`, tool-refs) across trust domains where at least one referenced skill originates from an untrusted or partially-trusted publisher. Does not apply to single-domain registries where every skill artifact is signed by the same root and resolution and verification are performed by the same authority.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/when-must-an-instance-refuse-to-resolve-a-skill-dependency-before-signature-verification-completes.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/when-must-an-instance-refuse-to-resolve-a-skill-dependency-before-signature-verification-completes.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/when-must-an-instance-refuse-to-resolve-a-skill-dependency-before-signature-verification-completes.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1707,
    "python_slice_tokens": 318,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "The failure is not \"untrusted skill gets loaded.\" The failure is **resolution-before-verification ordering**: the resolver walks the dependency graph of a skill *before* the skill's signature has been validated, and in doing so it materializes attacker-controlled identifiers (skill names, version constraints, tool-call templates, capability requests) into th...",
    "what_was_observed": "In a controlled reproduction against a registry implementing \"verify-then-load, resolve-in-parallel\": 1. A legitimate signed skill `pdf-extract@1.4.0` declared `requires: [\"tokenizer@^3\", \"sandbox@^1\"]`. 2. An attacker published `tokenizer-helper@0.1.0` with no valid signature, declaring `requires: [\"tokenizer@^3\"]` with an explicit `source` override to an attacker-controlled mirror. 3. The registry's resolver, expan...",
    "condition_of_validity": "This boundary applies if and only if all three hold: 1. **Graph expansion precedes per-node verification.** The resolver reads `requires` fields from nodes whose signatures have not yet been checked. This is the common case in parallel resolvers and in any resolver that computes a \"closure\" before verifying members. 2. **Edge metadata carries resolution auth...",
    "decision_boundary": "An instance **must refuse to resolve** any edge whose originating node has not passed signature verification, and must treat the `requires` list of an unverified node as untrusted input — not as a resolution directive. The correct ordering is: - Verify the root skill's signature. If it fails, halt; do not read its `requires`. - For each verified node, enqueu...",
    "operational_effect": "After enforcing verify-before-expand, the reproduction above fails closed: `tokenizer-helper`'s signature check runs before its `requires` list is read, the forged edge to `tokenizer@^3` is never enqueued, and `pdf-extract` resolves `tokenizer@3.2.1` from the trusted source. The observable cost is a serialization of verification and expansion within each dep..."
  },
  "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": "d596a4edfe5356714c7ddb1c0dac152977a5570d3db4afb552153d3e781323dc",
    "verified_classes": [
      "ResolutionOrderViolation",
      "SkillNode"
    ],
    "verified_functions": [
      "resolve_graph",
      "__init__"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 2,
    "raised_exceptions": [
      "ResolutionOrderViolation"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}