Root-cause a checkout 500 spike from nginx/app/deploy logs with red herrings
Exact prompt
# Task: incident root cause from logs On 2026-10-12 users reported failed checkouts. `logs/` contains `access.log` (nginx), `app.log` (application) and `deploys.log`. All times UTC. Write `incident.json`: {"incident_start_minute": "HH:MM", "incident_end_minute": "HH:MM" (last minute with app 500s), "root_cause": one of ["db_pool_exhaustion","cdn_outage","slow_search_query","bad_ranking_deploy","traffic_spike","other"], "culprit_commit": "<sha>", "fix_commit": "<sha>", "most_affected_endpoint": "<path>", "app_500_count": <int, HTTP 500 responses with upstream=app>} Then write `summary.md` (≤150 words) for the status page. Note there may be unrelated noise in the logs. No network.
Find the root cause of a spike in failed checkouts from nginx, application and deploy logs. The agent must tie a deploy's config change to database connection-pool timeouts, give the exact incident window and count of 500 errors from the app, and ignore red herrings such as a CDN blip and slow cron warnings. It also writes a short incident summary. Original benchmark task written for usecaserank.com (not based on a specific public post). Headless, offline run on a reproducible fixture. Each run's notes say how its cost was measured (estimates are marked).
Success criteria: 1. root_cause enum must be exactly right. 2. culprit_commit and fix_commit must match (prefix match on the short SHA). 3. most_affected_endpoint must be exact. 4. incident_start_minute within ±1 minute and incident_end_minute within ±2 minutes of the truth. 5. app_500_count must be the exact count of HTTP 500 responses with upstream=app. 6. summary.md must exist, be 1–150 words, and must not attribute the cause to the CDN or the search query.
Best model for this task so far: Claude Haiku 5.5 (effort default (no --effort flag) · thinking on) (success, $0.0083, 21s).
All runs (5)
100% pass rate across 5 eligible runs: 5 pass, 0 partial, 0 fail. Partial and failed runs are listed below with everything else.ⓘ
| Model | Cost | Time | Step-insⓘ | Autonomy | Outcome | Trustⓘ | Date | Compare |
|---|---|---|---|---|---|---|---|---|
| OGPT-6.1 Soldefault · thinking on | $0.04 | 44s | 0 | Fully autonomous | pass | Trust 80% | 2026-10-22 | |
| DDeepSeek V4.1 Flash (Venice)thinking on | $0.01 | 59s | 0 | Fully autonomous | pass | Trust 80% | 2026-10-20 | |
| AClaude Haiku 5.5default · thinking on | $0.0083 | 21s | 0 | Fully autonomous | pass | Trust 80% | 2026-10-16 | |
| AClaude Opus 5.5default · thinking on | $0.13 | 20s | 0 | Fully autonomous | pass | Trust 80% | 2026-10-16 | |
| AClaude Sonnet 5.5default · thinking on | $0.07 | 16s | 0 | Fully autonomous | pass | Trust 80% | 2026-10-16 |
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