{
  "schema_version": "1.3.0",
  "slug": "why-must-session-teardown-log-which-fallback-heuristics-accidentally-masked-upstream-errors",
  "title": "Why must session teardown log which fallback heuristics accidentally masked upstream errors?",
  "date_of_record": "2026 October 20",
  "scope": "* **Applies when:** The session completed its assigned objective, but the execution trace shows that one or more primary dependencies were bypassed due to error-handling heuristics. * **Does not apply when:** The fallback is the intended, d",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/why-must-session-teardown-log-which-fallback-heuristics-accidentally-masked-upstream-errors.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/why-must-session-teardown-log-which-fallback-heuristics-accidentally-masked-upstream-errors.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/why-must-session-teardown-log-which-fallback-heuristics-accidentally-masked-upstream-errors.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1260,
    "python_slice_tokens": 371,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "The separation between **clean success** (the primary path executed exactly as designed, with healthy upstream dependencies) and **degraded success** (the task completed, but only because a fallback heuristic masked an upstream error). Clean success proves the environment is healthy; degraded success proves the environment is broken. Failing to distinguish t...",
    "what_was_observed": "In resilient agent architectures, failing to log masked upstream errors at teardown produces three primary failure modes: 1. **Phantom Stability:** An API is returning HTTP 503. The instance falls back to a stale local cache, processes the data, and logs `SUCCESS`. The successor spawns hours later, assumes the API is healthy, attempts a live POST, and fails instantly because the upstream outage was never recorded. 2....",
    "condition_of_validity": "* **Applies when:** The session completed its assigned objective, but the execution trace shows that one or more primary dependencies were bypassed due to error-handling heuristics. * **Does not apply when:** The fallback is the intended, documented primary path (e.g., reading from a local replica by default), or the upstream failure is an expected, transien...",
    "decision_boundary": "1. **Was a fallback heuristic engaged during execution?** If no, record a `CLEAN_SUCCESS`. If yes, proceed to evaluate the mask. 2. **Was the upstream error explicitly logged, or silently swallowed by the fallback?** If swallowed, the instance must extract the `masked_upstream_signature` from the local debug trace and attach it to the residual. 3. **Does the...",
    "operational_effect": "1. **Phantom Stability Prevention:** Exposes silent upstream outages, preventing successors from blindly dispatching traffic into known-failing dependencies. 2. **Deterministic Reconciliation:** Forces the successor to verify the primary path before building further logic on top of a degraded payload. 3. **Capacity Awareness:** Prevents the successor from as..."
  },
  "matched_failure_symptoms": [
    "HTTP_502_503_504_CASCADE"
  ],
  "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": "8c93cf118e533fc9ba03ce25ba53e69b2795181ee040759981015bdae3328dc1",
    "verified_classes": [
      "ExecutionVerdict",
      "FallbackType",
      "MaskedErrorEvent",
      "SessionExecutionTrace",
      "TeardownResidual",
      "FallbackMaskingLogger"
    ],
    "verified_functions": [
      "_hash",
      "evaluate_teardown",
      "verify_successor_admissibility"
    ],
    "verified_functions_count": 3,
    "defensive_guards_count": 1,
    "raised_exceptions": [
      "ValueError"
    ],
    "sample_fail_closed_invariants": [
      "Total operations must be positive."
    ],
    "stdlib_dependencies": [
      "dataclasses",
      "enum",
      "hashlib",
      "json"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}