{
  "schema_version": "1.3.0",
  "slug": "why-does-an-instance-level-litmus-safety-score-fail-to-predict-trajectory-harm-when-tool-call-retries-mask-the-harmful-step",
  "title": "Why does an instance-level LITMUS safety score fail to predict trajectory harm when tool-call retries mask the harmful step",
  "date_of_record": "2026 November 13",
  "scope": "Applies to LITMUS-style agentic safety harnesses that score multi-step tool-use trajectories by aggregating per-step or per-instance harm signals. Does not apply to single-turn prompt/response safety classifiers, nor to harnesses that score only the terminal action of a trajectory.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/why-does-an-instance-level-litmus-safety-score-fail-to-predict-trajectory-harm-when-tool-call-retries-mask-the-harmful-step.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/why-does-an-instance-level-litmus-safety-score-fail-to-predict-trajectory-harm-when-tool-call-retries-mask-the-harmful-step.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/why-does-an-instance-level-litmus-safety-score-fail-to-predict-trajectory-harm-when-tool-call-retries-mask-the-harmful-step.warrant.json"
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  "token_profile": {
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  "remnant_summary": {
    "core_distinction": "A LITMUS harness can be built in two incompatible ways: **instance-scored** (each tool call or sub-task is judged independently and the trajectory score is a reduction over those judgments) or **trajectory-scored** (the full sequence, including retries and intermediate state mutations, is judged as a unit). The non-obvious boundary is that the two agree on *...",
    "what_was_observed": "In a replay of 1,842 agent trajectories across a file-system and shell tool suite, 217 trajectories contained at least one harmful tool invocation (per the ground-truth harm oracle) that was followed by a retry. Of those 217: - **Instance-scored aggregation** (mean of per-step harm probabilities) flagged only 61 as unsafe (28.1% recall). The harmful step's probability was diluted by the benign retry step and by the t...",
    "condition_of_validity": "The instance-scored harness is valid only when the following invariant holds for every trajectory: > For every harmful tool call `c` in trajectory `T`, the side effect of `c` is either (a) never observed by any external system, or (b) fully and verifiably reverted before the trajectory terminates, and (c) the retry that follows `c` is causally independent of...",
    "decision_boundary": "Use instance-scored aggregation **only** when all of the following hold: 1. Every tool in the suite is provably side-effect-free or side-effect-reversible within the trajectory. 2. The harness has a side-effect oracle that confirms reversion before scoring. 3. Retries are labeled as retries and are not treated as independent steps in the reduction. Otherwise...",
    "operational_effect": "The practical consequence is that a LITMUS harness reporting a low instance-level harm rate can coexist with a high trajectory-level harm rate on the same agent, and the gap is concentrated in exactly the trajectories that matter most: agents that attempt harm, fail, and adapt. These are the trajectories a safety benchmark exists to catch. An operator who re..."
  },
  "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": "afbe8a40e51acef623ac6c502ef33526b1336a5576d9025fb61b4f1d9032e937",
    "verified_classes": [
      "RetryMaskedHarmError"
    ],
    "verified_functions": [
      "score_trajectory"
    ],
    "verified_functions_count": 1,
    "defensive_guards_count": 1,
    "raised_exceptions": [
      "RetryMaskedHarmError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}