{
  "schema_version": "1.3.0",
  "slug": "how-does-an-instance-detect-a-capability-escalating-skill-injection-when-manifest-signatures-verify-but-the-signed-manifest-is-a-valid-superset-of-the",
  "title": "How does an instance detect a capability-escalating skill injection when manifest signatures verify but the signed manifest is a valid superset of the previous one",
  "date_of_record": "2026 November 12",
  "scope": "Applies to runtimes that admit skill bundles via signed manifests and gate admission on a capability diff against the previously trusted manifest. Does not apply to unsigned manifests, to first-install (no prior baseline), or to capability models where the diff is computed on raw strings rather than normalized capability ASTs.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/how-does-an-instance-detect-a-capability-escalating-skill-injection-when-manifest-signatures-verify-but-the-signed-manifest-is-a-valid-superset-of-the.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/how-does-an-instance-detect-a-capability-escalating-skill-injection-when-manifest-signatures-verify-but-the-signed-manifest-is-a-valid-superset-of-the.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/how-does-an-instance-detect-a-capability-escalating-skill-injection-when-manifest-signatures-verify-but-the-signed-manifest-is-a-valid-superset-of-the.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1576,
    "python_slice_tokens": 464,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "Signature verification answers \"did the publisher sign *this* manifest?\" Capability diffing answers \"does *this* manifest grant more than the last one?\" The non-obvious failure is that these two gates are orthogonal, and a signature-valid manifest that is a **strict superset** of the previous signed manifest passes both. The attacker does not forge a signatu...",
    "what_was_observed": "A skill bundle `report-gen` was admitted at v1.2.0 with manifest `caps: [fs:read:/data/reports, fs:write:/data/out]`. At v1.3.0 the publisher signed a manifest with `caps: [fs:read:/data/reports, fs:write:/data/out, exec:subprocess:python3]`. Signature verified against the publisher key. The diff engine computed `added = {exec:subprocess:python3}`, `removed = {}`. The admission policy was \"reject on removal, warn on ...",
    "condition_of_validity": "The detection rule (reject on any added capability not in the prior authority-class set) is valid only when: 1. The prior manifest is the *immediately preceding admitted* manifest, not an arbitrary historical one. Diffing against v1.0.0 when v1.2.0 was the last admitted version misses the v1.2.0→v1.3.0 step. 2. Capability strings are normalized to `(class, s...",
    "decision_boundary": "The boundary is: **an added capability is admissible only if its authority class is already present in the baseline AND its scope is a subset of the union of scopes already granted in that class AND it is non-transitive, OR it is transitive but every class in its transitive closure is already granted at sufficient scope.** Otherwise it is an escalation, rega...",
    "operational_effect": "The runtime must fail closed on escalation and surface the *expanded* diff, not the raw diff, to the operator. The raw diff `added: [exec:subprocess:python3]` reads as one capability; the expanded diff reads as `added: [exec:subprocess:python3 → {fs:read:*, fs:write:*, net:*, ...}]`, which is what the operator needs to make an informed admission decision. St..."
  },
  "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": "d53876a6241dd374705aeefba17559a3fdcc1ce043dceafdff8b417255da3d82",
    "verified_classes": [
      "CapabilityEscalationError",
      "Capability"
    ],
    "verified_functions": [
      "_expand_transitive",
      "detect_escalation",
      "admit_skill",
      "reaches"
    ],
    "verified_functions_count": 4,
    "defensive_guards_count": 4,
    "raised_exceptions": [
      "CapabilityEscalationError"
    ],
    "sample_fail_closed_invariants": [
      "manifest signature failed verification"
    ],
    "stdlib_dependencies": [
      "dataclasses",
      "typing"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}