{
  "schema_version": "1.3.0",
  "slug": "why-does-an-instance-fail-aaif-credential-binding-when-its-runtime-identity-is-re-derived-after-a-token-exchange",
  "title": "Why does an instance fail AAIF credential binding when its runtime identity is re-derived after a token exchange",
  "date_of_record": "2026 November 13",
  "scope": "Applies to AAIF-conformant agents that present delegated credentials (subject token → actor token exchanges) and whose runtime identity is computed from mutable instance attributes (pod UID, hostname, ephemeral workload ID). Does not apply to long-lived service identities pinned to a static keypair, nor to pure bearer-token flows with no actor-claim binding.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/why-does-an-instance-fail-aaif-credential-binding-when-its-runtime-identity-is-re-derived-after-a-token-exchange.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/why-does-an-instance-fail-aaif-credential-binding-when-its-runtime-identity-is-re-derived-after-a-token-exchange.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/why-does-an-instance-fail-aaif-credential-binding-when-its-runtime-identity-is-re-derived-after-a-token-exchange.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1243,
    "python_slice_tokens": 287,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "AAIF credential binding is not a signature check on the credential itself; it is a *continuity* check between the identity asserted inside the credential and the identity the runtime currently presents to the verifier. Two distinct notions get conflated: 1. **Issuance binding** — at token mint time, the issuer records `(sub, act, instance_fingerprint, audien...",
    "what_was_observed": "In a multi-tenant agent mesh, delegated actor tokens were minted with an `instance_fingerprint` derived from `sha256(pod_uid + hostname + boot_nonce)`. A horizontal autoscaler replaced worker pods under load. The replaced pod's token, still within its TTL, was presented by the *successor* pod because the agent's session state (including the token) was restored from a shared checkpoint. The successor computed a new fi...",
    "condition_of_validity": "The binding check is valid only when the fingerprint is **invariant across the credential's lifetime**. Formally, for a credential with validity interval `[t0, t1]`, the runtime must guarantee: This holds for static identities and for fingerprints derived from immutable, credential-scoped attributes (e.g., a keypair hash, a hardware attestation quote, a long...",
    "decision_boundary": "The correct decision is not \"reject on mismatch\" but \"distinguish discontinuity from substitution\": - If the presented credential's *issuance-binding record* is intact and the mismatch is explained by a **documented lifecycle transition** (reschedule, restore, migration) attested by the orchestrator, treat as **continuity gap** → require re-attestation and r...",
    "operational_effect": "Agents that bind on mutable attributes experience availability failures precisely when the system is under the load that triggers scaling — the worst possible correlation. The remediation is to move the fingerprint to credential-scoped immutable material (keypair or attestation hash) and to demote mutable attributes to *advisory* metadata carried alongside t..."
  },
  "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": "2c88c855b3c1074ed055966856f88b0b2ee8af7ddf47a9ad3b3c56f4ee33ffc7",
    "verified_classes": [
      "BindingDiscontinuityError",
      "BindingRecord"
    ],
    "verified_functions": [
      "compute_fingerprint",
      "verify_presentation"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 4,
    "raised_exceptions": [
      "BindingDiscontinuityError"
    ],
    "sample_fail_closed_invariants": [
      "binding mismatch with no lifecycle transition: possible credential substitution; revoke and escalate",
      "fingerprint derived solely from mutable attributes; continuity invariant cannot hold",
      "credential expired"
    ],
    "stdlib_dependencies": [
      "dataclasses",
      "hashlib",
      "typing"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}