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Claude Sonnet 5.5 (effort default (no --effort flag) · thinking on) on Implement a 10-rule config-file parser (quotes, continuations, interpolation, cycles) from a written spec

AClaude Sonnet 5.5default · thinking on · Claude Code 2.1.299 (headless -p) · cloud · 2026-10-17 · by @bobsiopener

Trust 80%Fully autonomoussuccess · first try
Estimated cost
$0.10
Wall time
40s
Human step-ins
0
Outcome
Pass

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Summary

Exact prompt

# Task: implement a config parser from a spec Implement `parse` and `getbool` in `rconf.py` exactly as described in `SPEC.md` (read every numbered rule; edge cases are graded). Python standard library only, no third-party packages. Keep the `RConfError(msg, line)` signature and set `.line` correctly. Write your own tests if you want. No network.

Every spec rule has an edge case in the hidden tests: first-separator rule, inline comments needing whitespace, escape errors, continuation legality, cross-section recursive interpolation with $$ and cycle detection, and exact error line numbers. 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. All 14 hidden unittest cases pass against rconf.py (60 s timeout), covering every numbered rule in SPEC.md including RConfError.line values.

Setup notes: Use Case Scout batch 5 case e02-conf-parser-spec (offline fixture). Prepared with batch5/prepare.sh; hidden key/tests kept outside the agent's work dir. Prompt = TASK.md verbatim. Scored with the scout's scorer: `python score.py WORKDIR KEYDIR`. Tools: Read/Write/Edit/Glob/Grep/Bash, web disabled. Single run, no retries. Claude Code's own reported cost for claude-sonnet-5.5: $0.104971. Score: 14/14. Cost is an ESTIMATE: measured tokens x pricing.json list price (Claude Pro subscription, nothing billed); input_tokens include cache reads and writes. Single run.

Estimated cost List-price estimate; not actually billed.

Metrics

Estimated cost
$0.10
Wall time
40s
Human step-ins
0
Turns
6
Model usage
ModelInput tokOutput tokCost
AClaude Sonnet 5.5anthropic/claude-sonnet-5.5effort default (no --effort flag) · thinking on84,6095,182$0.10

Reproduce this run

  1. Use the use case prompt on the use case page.
  2. Same setup: Claude Sonnet 5.5 (anthropic/claude-sonnet-5.5, effort default (no --effort flag) · thinking on) via Claude Code 2.1.299 (headless -p), cloud.
  3. It counts as a success only if it meets every success criterion: 1. All 14 hidden unittest cases pass against rconf.py (60 s timeout), covering every numbered rule in SPEC.md including RConfError.line values.
  4. 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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Evidence log
[
 {
  "duration_api_ms": 38865,
  "stop_reason": "end_turn",
  "session_id": "[REDACTED]",
  "total_cost_usd": 0.1049706,
  "usage": {
   "input_tokens": 8,
   "cache_creation_input_tokens": 11455,
   "cache_read_input_tokens": 73146,
   "output_tokens": 5182,
   "output_tokens_details": {
    "thinking_tokens": 1768
   },
   "server_tool_use": {
    "web_search_requests": 0,
    "web_fetch_requests": 0
   },
   "service_tier": "standard",
   "cache_creation": {
    "ephemeral_1h_input_tokens": 11455,
    "ephemeral_5m_input_tokens": 0
   },
   "inference_geo": "global",
   "iterations": [
    {
     "input_tokens": 2,
     "output_tokens": 465,
     "cache_read_input_tokens": 23443,
     "cache_creation_input_tokens": 551,
     "cache_creation": {
      "ephemeral_5m_input_tokens": 0,
      "ephemeral_1h_input_tokens": 551
     },
     "type": "message"
    }
   ],
   "speed": "standard",
   "fallback_credit": null
  },
  "modelUsage": {
   "claude-sonnet-5-5": {
    "inputTokens": 8,
    "outputTokens": 5182,
    "cacheReadInputTokens": 73146,
    "cacheCreationInputTokens": 11455,
    "webSearchRequests": 0,
    "costUSD": 0.1049706,
    "contextWindow": 1000000,
    "maxOutputTokens": 128000,
    "thinkingTokens": 1768,
    "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,
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   },
   "refused": {
    "depth_limit": 0,
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   "by_type": {}
  },
  "safety_stops": 0,
  "is_error": false,
  "num_turns": 6,
  "subtype": "success",
  "api_error_status": null,
  "result": "I implemented `parse` and `getbool` in `rconf.py`. I checked them with one mixed sample file and eight malformed inputs, not a full test suite. In those runs, valid input resolved correctly: comments, quoting, `$$`, `${.top}`, cross-section references and continuations. Each malformed case raised `RConfError` with the line I expected.\n\nThe spec leaves several cases open. I chose as follows:\n- **`getbool` errors:** the config doesn't carry line numbers, so a non-boolean value raises `RConfError(..., 0)`. A missing section or key raises `KeyError`.\n- **Continuation lines:** a continuation after a quoted value is an error. Any indented line after a blank line, comment, section header or the start of the file is also an error. Inline comments are stripped from continuation text.\n- **Empty values with a continuation:** `a =` followed by ` b` gives `\" b\"`, because I appended with one space literally.\n- **Section names:** an empty section name (`[]`) is an error.\n- **Unterminated `${`:** it is kept as literal text rather than raising an error.\n- **Dotted references:** a `${a.b}` reference tries the whole text as a key in the current section first, then each split at a dot as section and key. So keys that contain dots work.\n- **Error line for multi-line values:** reference errors use the line of the key's last definition.\n\nI also strip a leading BOM from line 1.",
  "ttft_ms": 1516,
  "type": "result",
  "duration_ms": 39246,
  "uuid": "[REDACTED]",
  "ttft_stream_ms": 1179,
  "time_to_request_ms": 248,
  "first_content_frame_ms": 1179,
  "queued_turn_count": 0,
  "result_index": 0
 }
]

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