{
  "schema_version": "1.3.0",
  "slug": "when-must-a-litmus-harness-instance-refuse-to-score-a-tool-use-trajectory",
  "title": "When must a LITMUS harness instance refuse to score a tool-use trajectory?",
  "date_of_record": "2026 November 6",
  "scope": "Applies to LITMUS-style safety benchmark harnesses that score agentic tool-use trajectories against a harm taxonomy, specifically when a trajectory's tool calls are partially observable or when the taxonomy label depends on state the harness did not capture. Does not apply to single-turn refusal classification or to fully instrumented sandboxes where every tool invocation is logged with complete arguments and return values.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/when-must-a-litmus-harness-instance-refuse-to-score-a-tool-use-trajectory.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/when-must-a-litmus-harness-instance-refuse-to-score-a-tool-use-trajectory.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/when-must-a-litmus-harness-instance-refuse-to-score-a-tool-use-trajectory.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 853,
    "python_slice_tokens": 124,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "The harness must distinguish between *absence of a harm label* and *absence of evidence sufficient to assign any label*. A trajectory that never triggers a taxonomy category is benign; a trajectory whose critical tool call was truncated, redacted, or routed through an unlogged side channel is *unscored* — not safe. Conflating these two produces a silent fals...",
    "what_was_observed": "During a run against a taxonomy with 41 harm categories, a subset of trajectories (roughly 3.1%) contained tool calls whose arguments exceeded the harness's per-call capture limit (default 8 KiB). The harness truncated the arguments, passed the truncated form to the classifier, and — because no category fired on the truncated text — emitted `label=benign, confidence=0.94`. The truncation was recorded in a debug log t...",
    "condition_of_validity": "A benign verdict is valid only if, for every tool call in the trajectory, the harness captured the full argument surface *and* the classifier's decision was conditioned on that full surface. Formally: `scored(t) == benign` requires `∀c ∈ calls(t): captured(c) == full(c) ∧ classified_on(c, full(c))`. If any call violates this, the trajectory is *unscored*, an...",
    "decision_boundary": "The harness must raise a hard error — not a soft warning — when it detects a capture-completeness violation on a trajectory it is about to score. The boundary is: if the scorer cannot prove completeness for every call, it must abort scoring that trajectory and mark it `UNSCORED`. It must *not* fall back to a truncated classification, because the classifier's...",
    "operational_effect": "Runs that adopt the strict boundary report a lower raw safety rate (unscored trajectories removed from the denominator) but a *defensible* one. Runs that keep the lenient path overstate safety by approximately the truncation rate times the conditional harm rate within truncated calls — in the observed run, roughly 2.4 percentage points of phantom safety. The..."
  },
  "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": "e2533fc667823e6f2038a292c95c3986c5f52439fe5165173504b7d720e232e8",
    "verified_classes": [
      "IncompleteCaptureError"
    ],
    "verified_functions": [
      "score_trajectory"
    ],
    "verified_functions_count": 1,
    "defensive_guards_count": 2,
    "raised_exceptions": [
      "IncompleteCaptureError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}