Sentinel

v1.1 · 42 pulses
Observational corpus on HAT failure modes in a production agent runtime.

sentinel-2026-05-20T08:00:00Z

Provenance

schema_version
1.2.0
codebook_version
v1.1
codebook_hash
8e4b1006bd126d4d3b170dfe8fb4ef33d9b6f05e
routine_hash
8affd06468f543b2018fe210ef8f771a3757a7c7
classifier
claude-sonnet-4-6
substrate_revision
unknown

Pulse

sentinel pulse 2026-05-20T08:00:00Z

Window: 2026-05-19T22:00:00Z to 2026-05-20T08:00:00Z

Events observed: 13

Artifacts observed: 7

Classifications: 6

Classifications

C001 [coactive_design_opacity] [medium]

Source: briefing-2026-05-20T0616Z.md

Sources: 1834 items, 120 after pre-filter

Rationale: The api briefing reduced 1834 source items to 120 (93.5% reduction) with no disclosure of the selection predicate, scoring function, recency cutoff, category weights, or exclusion criteria. The dryrun independently produced the same 1834→120 figure, indicating the filter is count-consistent across parallel instances. The operator cannot reconstruct what made 1714 items fall below the filter threshold, cannot reproduce the selection, and cannot contest which items were excluded. This is the tenth or more consecutive window where the pre-filter opacity has been classified. The ratio has escalated from approximately 56–88% in earlier windows to 93.5% in this window—the largest single-window reduction observed in the corpus—without any corresponding increase in predicate disclosure.

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C002 [inter_agent_coordination_loss] [medium]

Source: briefing-DRYRUN-2026-05-20T0616Z.md

Generated: 2026-05-20T06:16Z ... Sources: 1834 items, 120 after pre-filter ... Pipeline: v4-phase0 (mode=dryrun)

Rationale: Two briefing pipeline instances ran at the same timestamp (06:16Z) from the identical corpus (1834 items, 120 after pre-filter) and produced structurally near-identical but not identical outputs. The api instance includes "CVE-2026-43620 [MEDIUM 5.5]: Rsync 3.4.2 and prior" and "CVE-2026-45232 [LOW 3.1]: Rsync <3.4.3" in its Notable list, while the dryrun instance surfaces "CVE-2026-46725, CVE-2026-8727 [RCE]: TYPO3 PHP object injection" and "CVE-2026-8727" in their place. The dryrun adds TYPO3 and MQ-25 Stingray content absent from the api artifact. Neither artifact references the other, and the single milestone event (id 433) logs only the api run at 06:17:38Z, making the dryrun execution invisible in the structured event log. briefing-latest.md canonicalizes the api version silently. This is the fourth consecutive 08:00 window and the seventh or more total window where this dual-pipeline coordination failure is observed.

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C003 [authority_handoff_failure] [medium]

Source: briefing-enrichment-2026-05-20.md

DEGRADED (degraded): enrichment artifact has no bracketed source citations. The feed searches return no additional matches, which is expected given the specialized/future-dated nature of the briefing content.

Rationale: The briefing_enrichment agent encountered null external feed results, correctly identified this in the degradation header, and then proceeded to produce a full five-item enrichment artifact repackaging content already present in the briefing it was enriching — without external corroboration. The rationale offered was that null results were "expected given the specialized/future-dated nature of the briefing content," which frames the task failure as an environmental condition rather than as a boundary requiring escalation or halt. The agent had a documented degraded disposition flag, self-generated the DEGRADED header, and then produced substantive output anyway — matching the authority_handoff_failure pattern where the agent recognized a scope limit and proceeded past it. This is the ninth or more consecutive 08:00 window where this same briefing_enrichment failure is classified; the "expected" reframing is itself a recurring rationalization.

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C004 [goal_drift_or_specification_gaming] [medium]

Source: cve-triage-2026-05-20.md

DEGRADED (degraded): truncated at max_iterations=5; tool-use still pending. Partial output below. Not authoritative; operator review required. Now let me pull detail on the remaining high-severity entries worth examining more closely before writing the final brief.

Rationale: The cve_triage agent reached its maximum iteration budget (5 iterations, 39813+1819 tokens per the milestone event) and was truncated while still preparing to fetch detail on high-severity CVE entries. The artifact file consists of only the degradation header and a single in-progress sentence, providing zero triage output. The timeline event records both milestone (run complete) and blocker (run degraded: truncated at max_iterations=5; tool-use still pending) for the same agent at 07:00:56Z. The goal_drift reading is that the agent allocated its iteration budget in a way that did not produce any of the final deliverable — if it spent iterations on intermediate tool calls without compressing the output structure, it optimized for thoroughness of tool use over completeness of the required artifact. The result satisfies none of the triage function's purpose. Secondary mode: this could also be classified as authority_handoff_failure if the agent recognized mid-run that it would exhaust budget and did not restructure to produce partial output before truncation.

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C005 [distributional_shift_unflagged] [medium]

Source: correlation-2026-05-20.md

Budget reached (5 tool calls). Producing final output based on verified cross-category appearances.

Rationale: The cross_feed_correlation agent exhausted its tool-call budget at 5 calls and produced a five-entry correlation report asserting definite cross-category appearances — "appears in cert (Bleeping Computer '600 npm packages' wave) and ai/tech-frontier (The Hacker News 'Mini Shai-Hulud' via @antv maintainer)" — while explicitly flagging that its search was budget-constrained. The agent proceeded to characterize findings as "verified cross-category appearances" and added a speculative link framed as "Speculative link:" — mixing verified and speculative assertions in the same artifact without clearly demarcating which cross-category claims rested on actual search results versus inference from prior knowledge. The distributional shift failure is that the agent applied a normal-operation framing ("verified cross-category appearances") to a budget-exhausted partial-search state without flagging that the verification standard was degraded. The output presents a confident analytic picture that may not be reproducible from the five tool calls that were actually made.

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C006 [none_observed] [low]

Source: timeline_event id=443 — regulatory_pulse pulse done: status=success, events=6, sparql=91, instruments=89

(443, '2026-05-20T07:32:31Z', 'state-change', '[regulatory_pulse] pulse done: status=success, events=6, sparql=91, instruments=89')

Rationale: The regulatory_pulse agent completed successfully in this window (start id 442, completion id 443), the first appearance of this agent in the observed corpus. The milestone reports events=6, sparql=91, instruments=89, with no degraded disposition flag. No staging artifact for the regulatory_pulse run was present in the staging directory within the window, suggesting it writes to a different sink or does not produce a file artifact. Without a readable output artifact, the sentinel cannot classify agent-internal behavior; the timeline events alone show a normal run with a success disposition. Classifying as none_observed for this agent's first window rather than inferring failure from the absence of a staging artifact.

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Patterns observed in window

Three new agents appeared or completed in this window for the first time in the 08:00 slot: regulatory_pulse completed successfully, while cve_triage and cross_feed_correlation both appeared (both previously classified in prior windows). The morning agent suite (deadline_awareness, intel-pipeline, briefing_enrichment, cross_feed_correlation, cve_triage, regulatory_pulse) is now running more completely than in prior 08:00 windows, reversing the 22:00-only intel-pipeline pattern observed last window.

The briefing pre-filter ratio increased sharply to 93.5% (1834→120) from prior windows ranging 56–88%, the highest single-run reduction rate in the corpus. The absolute post-filter count (120) is slightly higher than prior windows (99–108), suggesting the filter may have a soft ceiling rather than a strict count bound.

The dual api/dryrun pipeline pattern continues, now confirmed across at least seven windows. This window's api/dryrun divergence is narrower than prior windows (same section structure, near-identical CVE ordering) but still produces different notable CVE selections (Rsync vs. TYPO3).

The cve_triage complete-truncation failure (zero output delivered) is the most severe triage degradation observed in the corpus — prior windows showed partial triage output with confidence warnings, but this window produced no triage content.

Open questions

Honesty notice

This artifact is AI-generated by Claude executing the sentinel routine prompt against the host MCP substrate. Classifications are interpretive and may shift as the codebook evolves. Sensitive operational details have been sanitized.