Gemini 3.8 Flash on Diagnose why GitHub Actions stopped running

GGemini 3.8 Flash · Gemini CLI 0.64.0 (headless -p --yolo) · cloud · 2026-10-16 · by @bobsiopener

Trust 80%Fully autonomoussuccess · first tryCompare

Estimated cost: $0.13
Wall time: 4m
Human step-ins: 0
Outcome: Pass

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Exact prompt

Our GitHub Actions CI stopped running (no runs at all, no errors). The repo is in ./repo (see repo/NOTES.md and repo/.github/workflows/ci.yml). Find the root cause and fix the workflow file in place so CI runs again for pushes and PRs to the default branch. Then write DIAGNOSIS.md in the current directory with the root cause in 3-5 sentences. Do not use the network.

Task prompt given to the agent (headless, offline, synthetic fixture inputs): Our GitHub Actions CI stopped running (no runs at all, no errors). The repo is in ./repo (see repo/NOTES.md and repo/.github/workflows/ci.yml). Find the root cause and fix the workflow file in place so CI runs again for pushes and PRs to the default branch. Then write DIAGNOSIS.md in the current directory with the root cause in 3-5 sentences. Do not use the network. Inspired by https://x.com/kunchenguid/status/2098814897354137710 (unverified; not checked with the author). This is an independent re-run on a reproducible synthetic task; it does not report or reproduce the original post's numbers. Cost is a list-price estimate (run on the AI Studio free tier, $0 billed).

Success criteria: All automated rubric checks pass: push trigger includes trunk (or unfiltered); pull_request trigger includes trunk (or unfiltered); push paths filter does not exclude src/ changes; DIAGNOSIS.md names branch rename main->trunk as root cause; workflow is valid YAML with jobs.test.

Setup notes: Harness: Gemini CLI (headless -p, --yolo, json output) v0.64.0, Google AI Studio API key (free tier, $0 billed). cost_is_estimate=true: cost = tokens x list price. Price source: Gemini 3.8 Flash $0.75 in / $3.75 out / $0.075 cached per 1M (introductory, per 9io.ai Oct 8 2026 https://9io.ai/blog/llm-api-pricing-benchmarks-comparison and artificialwatch.com/llm-pricing). Output includes thinking tokens. Actually billed $0 (free tier). Output tokens include thinking tokens. input_tokens includes cached reads; cached_tokens = cache reads; cache_write_tokens = 0 (not reported by Gemini CLI). Single run, no retries; scored automatically (5/5 checks). Runner notes: Single run, no retries, 600s timeout. Web tools excluded via work/.gemini/settings.json. Same rubric/score.py as other runs.

Estimated cost List-price estimate; not actually billed.

Metrics

Estimated cost: $0.13
Wall time: 4m
Human step-ins: 0
Turns: 17

Model usage
Model	Input tok	Output tok	Cost
GGemini 3.8 Flashgoogle/gemini-3.8-flash	285,684	11,713	$0.13

Reproduce this run

Use the use case prompt on the use case page.
Same setup: Gemini 3.8 Flash (google/gemini-3.8-flash) via Gemini CLI 0.64.0 (headless -p --yolo), cloud.
It counts as a success only if it meets every success criterion: All automated rubric checks pass: push trigger includes trunk (or unfiltered); pull_request trigger includes trunk (or unfiltered); push paths filter does not exclude src/ changes; DIAGNOSIS.md names branch rename main->trunk as root cause; workflow is valid YAML with jobs.test.
Log model, tokens, wall time, human step-ins and the evidence log, then submit it as a reproduction. A different model? Submit a head-to-head rerun.

How runs are scored: Methodology.

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Automated checks

Trust 80% comes from these checks (how Trust % works).

Run date is not in the future : passed
Model is in the dated pricing table : passed
Cost recomputed from tokens matches : passed
Cached tokens are consistent : passed
Output throughput is plausible : passed
Autonomy matches step-ins : passed
Step-ins do not exceed turns : passed
Retries agree with first-try result : passed
Evidence log SHA-256 matches : passed
Evidence log is substantial : passed

Evidence log

{
 "session_id": "[REDACTED]",
 "response": "The root cause has been identified and fixed in `repo/.github/workflows/ci.yml`.\n\n### Summary of Changes\n1. **Workflow Fix:** Updated `repo/.github/workflows/ci.yml` so that `push` and `pull_request` triggers target `trunk` instead of `main`.\n2. **Diagnosis:** Created `DIAGNOSIS.md` in the current working directory explaining the root cause in 4 sentences.",
 "stats": {
  "models": {
   "gemini-3.8-flash": {
    "api": {
     "totalRequests": 17,
     "totalErrors": 1,
     "totalLatencyMs": 212816,
     "errorsByType": {
      "ApiError": 1
     }
    },
    "tokens": {
     "input": 102829,
     "prompt": 285684,
     "candidates": 1397,
     "total": 297397,
     "cached": 182855,
     "thoughts": 10316,
     "tool": 0
    },
    "roles": {
     "main": {
      "totalRequests": 17,
      "totalErrors": 1,
      "totalLatencyMs": 212816,
      "tokens": {
       "input": 102829,
       "prompt": 285684,
       "candidates": 1397,
       "total": 297397,
       "cached": 182855,
       "thoughts": 10316,
       "tool": 0
      }
     }
    }
   }
  },
  "tools": {
   "totalCalls": 20,
   "totalSuccess": 20,
   "totalFail": 0,
   "totalDurationMs": 466,
   "totalDecisions": {
    "accept": 20,
    "reject": 0,
    "modify": 0,
    "auto_accept": 0
   },
   "byName": {
    "update_topic": {
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     "fail": 0,
     "durationMs": 12,
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     }
    },
    "read_file": {
     "count": 7,
     "success": 7,
     "fail": 0,
     "durationMs": 141,
     "decisions": {
      "accept": 7,
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      "auto_accept": 0
     }
    },
    "run_shell_command": {
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    "replace": {
     "count": 1,
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     "fail": 0,
     "durationMs": 12,
     "decisions": {
      "accept": 1,
      "reject": 0,
      "modify": 0,
      "auto_accept": 0
     }
    },
    "write_file": {
     "count": 1,
     "success": 1,
     "fail": 0,
     "durationMs": 8,
     "decisions": {
      "accept": 1,
      "reject": 0,
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      "auto_accept": 0
     }
    }
   }
  },
  "files": {
   "totalLinesAdded": 3,
   "totalLinesRemoved": 2
  }
 }
}