{
  "schema_version": "1.3.0",
  "slug": "what-invariants-detect-silent-non-determinism-introduction-by-external-tools",
  "title": "What invariants detect silent non-determinism introduction by external tools?",
  "date_of_record": "2026 October 20",
  "scope": "* **Applies when:** The session depends on a tool's determinism, the tool can silently become non-deterministic, and downstream logic assumes determinism. * **Does not apply when:** The tool is documented as non-deterministic, or the sessio",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/what-invariants-detect-silent-non-determinism-introduction-by-external-tools.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/what-invariants-detect-silent-non-determinism-introduction-by-external-tools.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/what-invariants-detect-silent-non-determinism-introduction-by-external-tools.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1032,
    "python_slice_tokens": 334,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "The separation between **documented determinism** (the tool's claimed behavior contract) and **observed determinism** (the tool's actual behavior across repeated calls). Relying on the contract creates the **Silent Non-Determinism Drift**: the tool was deterministic when the session's assumptions were set, has since become non-deterministic, and the session'...",
    "what_was_observed": "In deterministic-tool-dependent agent architectures, failing to detect silent non-determinism produces three primary failure modes: 1. **Cache Corruption:** The session caches tool responses assuming determinism. The tool becomes non-deterministic, the cache serves stale responses that no longer match the tool's actual output, and downstream consumers act on data the tool would no longer return. 2. **Idempotency Brea...",
    "condition_of_validity": "* **Applies when:** The session depends on a tool's determinism, the tool can silently become non-deterministic, and downstream logic assumes determinism. * **Does not apply when:** The tool is documented as non-deterministic, or the session's logic is determinism-agnostic.",
    "decision_boundary": "1. **Does the session assume tool determinism?** If no, standard tool use applies. If yes, proceed. 2. **Is a `determinism_baseline_receipt` available?** If yes, the session can detect drift. If no, all determinism assumptions are unverified. 3. **Does the `determinism_probe_receipt` show drift from baseline?** If yes, the tool has become non-deterministic. ...",
    "operational_effect": "1. **Cache Integrity:** Caching remains sound because determinism is monitored. 2. **Idempotency Preservation:** Retries remain safe because determinism is preserved. 3. **Divergence Attribution:** Silent drift is caught and attributed to the tool, not to session bugs."
  },
  "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": "3fb42f37bc3955b9c0c61c2a51955100248658d67043e84f47834c07f4b5849b",
    "verified_classes": [
      "DeterminismVerdict",
      "DeterminismBaseline",
      "DeterminismProbe",
      "SessionDeterminismContext",
      "DeterminismPolicy",
      "DeterminismManifest",
      "SilentNondeterminismGuard"
    ],
    "verified_functions": [
      "_hash",
      "evaluate_probe"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 0,
    "raised_exceptions": [],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
      "dataclasses",
      "enum",
      "hashlib",
      "json"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}