Claude Sonnet 5.5 on Analyze five months of AI coding-agent session logs

AClaude Sonnet 5.5 · Claude Code 2.1.299 (headless -p) · cloud · 2026-10-14 · by @bobsiopener

Trust 80%Fully autonomoussuccess · first tryCompare

Estimated cost: $0.05
Wall time: 14s
Human step-ins: 0
Outcome: Pass

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Exact prompt

sessions.csv logs 5 months of AI coding-agent sessions. Write answers.json with exactly these keys: "total_sessions" (int), "total_prs" (int), "total_api_equiv_usd" (number rounded to 2 decimals), "busiest_month_by_sessions" (string like "2026-07"), "median_minutes" (number), "usd_per_pr_by_tool" (object tool -> total api_equiv_usd / total prs_opened for that tool, rounded to 2 decimals). Then write REPORT.md with a 5-bullet summary.

Task prompt given to the agent (headless, offline, synthetic fixture inputs): sessions.csv logs 5 months of AI coding-agent sessions. Write answers.json with exactly these keys: "total_sessions" (int), "total_prs" (int), "total_api_equiv_usd" (number rounded to 2 decimals), "busiest_month_by_sessions" (string like "2026-07"), "median_minutes" (number), "usd_per_pr_by_tool" (object tool -> total api_equiv_usd / total prs_opened for that tool, rounded to 2 decimals). Then write REPORT.md with a 5-bullet summary. Inspired by https://x.com/quinn_leng/status/2085828592127336541 (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 shown is a list-price API-equivalent estimate (run on a Claude Pro subscription, not billed).

Success criteria: All automated rubric checks pass: total_sessions correct; total_prs correct; total_api_equiv_usd correct; busiest_month_by_sessions correct; median_minutes correct; usd_per_pr_by_tool correct; REPORT.md written.

Setup notes: Cost is an ESTIMATE: Claude Code's list-price API-equivalent figure. The run used a Claude Pro subscription, so nothing was billed. input_tokens = all input incl. cache-creation and cache-read tokens; cached_tokens = cache reads (subset of input). Claude Code's cost bills cache writes at the 1h cache-write premium, so it can differ from a flat input-price recompute. Web disabled; tools Read/Write/Edit/Glob/Grep/Bash; single run; scored automatically (7/7 checks).

Estimated cost List-price estimate; not actually billed.

Metrics

Estimated cost: $0.05
Wall time: 14s
Human step-ins: 0
Turns: 5

Model usage
Model	Input tok	Output tok	Cost
AClaude Sonnet 5.5anthropic/claude-sonnet-5.5	94,842	1,360	$0.05

Reproduce this run

Use the use case prompt on the use case page.
Same setup: Claude Sonnet 5.5 (anthropic/claude-sonnet-5.5) via Claude Code 2.1.299 (headless -p), cloud.
It counts as a success only if it meets every success criterion: All automated rubric checks pass: total_sessions correct; total_prs correct; total_api_equiv_usd correct; busiest_month_by_sessions correct; median_minutes correct; usd_per_pr_by_tool correct; REPORT.md written.
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

{
 "duration_api_ms": 11982,
 "stop_reason": "end_turn",
 "session_id": "[REDACTED]",
 "total_cost_usd": 0.05208020000000001,
 "usage": {
  "input_tokens": 10,
  "cache_creation_input_tokens": 7430,
  "cache_read_input_tokens": 87402,
  "output_tokens": 1360,
  "output_tokens_details": {
   "thinking_tokens": 0
  },
  "server_tool_use": {
   "web_search_requests": 0,
   "web_fetch_requests": 0
  },
  "service_tier": "standard",
  "cache_creation": {
   "ephemeral_1h_input_tokens": 7430,
   "ephemeral_5m_input_tokens": 0
  },
  "inference_geo": "global",
  "iterations": [
   {
    "input_tokens": 2,
    "output_tokens": 349,
    "cache_read_input_tokens": 19738,
    "cache_creation_input_tokens": 231,
    "cache_creation": {
     "ephemeral_5m_input_tokens": 0,
     "ephemeral_1h_input_tokens": 231
    },
    "type": "message"
   }
  ],
  "speed": "standard",
  "fallback_credit": null
 },
 "modelUsage": {
  "claude-sonnet-5-5": {
   "inputTokens": 10,
   "outputTokens": 1360,
   "cacheReadInputTokens": 87402,
   "cacheCreationInputTokens": 7430,
   "webSearchRequests": 0,
   "costUSD": 0.05208020000000001,
   "contextWindow": 1000000,
   "maxOutputTokens": 128000,
   "thinkingTokens": 0,
   "canonicalModel": "claude-sonnet-5-5",
   "provider": "firstParty",
   "costBasis": "list"
  }
 },
 "permission_denials": [],
 "terminal_reason": "completed",
 "fast_mode_state": "off",
 "fast_mode_disabled_reason": "sdk_opt_in_required",
 "subagent_stats": {
  "spawned": 0,
  "requested": {
   "background": 0,
   "foreground": 0,
   "unset": 0
  },
  "started_in_background": 0,
  "max_depth": 0,
  "spawned_by_subagents": 0,
  "completed": 0,
  "failed": 0,
  "killed": {
   "parent": 0,
   "user": 0,
   "system": 0
  },
  "refused": {
   "depth_limit": 0,
   "concurrency_limit": 0,
   "budget": 0
  },
  "by_type": {}
 },
 "safety_stops": 0,
 "is_error": false,
 "num_turns": 5,
 "subtype": "success",
 "api_error_status": null,
 "result": "I wrote `answers.json` and `REPORT.md` in the working directory. The CSV was clean: 400 rows, no missing values, no duplicate session IDs, and only two tools.\n\n| Key | Value |\n|---|---|\n| `total_sessions` | 400 |\n| `total_prs` | 256 |\n| `total_api_equiv_usd` | 4843.16 |\n| `busiest_month_by_sessions` | 2026-09 (89 sessions) |\n| `median_minutes` | 88.5 |\n| `usd_per_pr_by_tool` | claude-code 19.50, codex 18.39 |\n\n- **Per-tool totals:** claude-code had 195 sessions, 122 PRs and $2,378.50 of spend. codex had 205 sessions, 134 PRs and $2,464.66.\n- **Close month:** 2026-05 was a near tie for busiest, with 88 sessions.\n- **`REPORT.md`:** its five bullets cover volume, PRs, cost, busiest month with median session length, and cost per PR.",
 "ttft_ms": 2253,
 "type": "result",
 "duration_ms": 13417,
 "uuid": "[REDACTED]",
 "ttft_stream_ms": 1452,
 "time_to_request_ms": 425,
 "first_content_frame_ms": 1453,
 "queued_turn_count": 0,
 "result_index": 0
}