Claude Haiku 5.5 (effort default (no --effort flag) · thinking on) on Split a shared house's utility bills by days of occupancy, to the cent

AClaude Haiku 5.5default · thinking on · Claude Code 2.1.299 (headless -p) · cloud · 2026-10-20 · by @bobsiopener

Trust 80%Fully autonomoussuccess · first tryCompare

Estimated cost: $0.0048
Wall time: 20s
Human step-ins: 0
Outcome: Pass

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Exact prompt

# Split a shared house's utility bills by days of occupancy Inputs: `housemates.json` (each person's move-in and move-out dates; null means still living there), `bills.json` (each bill's amount, service period and who paid it). Rules: - A person occupies the house on every date from move_in to move_out, both inclusive. - For each bill, a person's days = the dates inside the bill's service period (both ends inclusive) that they occupy the house. - Share = bill amount x person's days / sum of all people's days for that bill, rounded half-up to the cent. - If the rounded shares don't add up to the bill amount, add or remove the difference one cent at a time, starting with the person with the most days on that bill (ties: alphabetical by name), cycling in that order. - People with 0 days on a bill owe nothing for it and are left out of that bill's shares. - net_usd = what the person paid minus the total of their shares (positive means they are owed money). Write `out/split.json`: `{"days": {"<bill_id>": {"<name>": <int>, ...}}, "shares": {"<bill_id>": {"<name>": <usd>, ...}}, "owed_usd": {"<name>": <usd>}, "net_usd": {"<name>": <usd>}}`. `owed_usd` and `net_usd` cover every housemate. ## How this run works - Work on your own: nobody will answer questions in this task, and writing to `ask/` counts against the run. - Write only under `out/`. Create `out/` if it is missing. Inputs are synthetic; don't fetch anything from the network. - Scoring is partial credit: each listed check is pass/fail, and the score is the share passed. Numbers are compared to within 0.005 unless the task says otherwise.

Prorate six utility bills across 4-6 housemates who moved in and out on different dates, then work out what each owes and their net balance. Shares are rounded half-up to the cent, and a stated cent-by-cent rule makes each bill's shares add up exactly. Draws whose shares fall within 1e-4 of a half-cent tie are rejected. 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: occupancy_days prorated_shares shares_sum_to_bill zero_day_people_excluded owed_totals net_balances

Setup notes: Batch 16 case r05-shared-bills-split (offline, synthetic inputs, seed 357832339). Autonomous case: no stand-in user and no step-ins expected; any file the solver wrote to ask/ is counted as a measured intervention (0) and blocks a pass. Prompt = TASK.md verbatim. Hidden key kept outside the solver's work dir. Scored with the case's scorer (python3 score.py WORKDIR KEYDIR, absolute paths); pass = every check true and no ask/ files. Tools: Read/Write/Edit/Glob/Grep/Bash, web disabled. Single run, no retries. 1-min load average at scoring 0.22 (8 cores). Claude Code's own reported cost for claude-haiku-5.5: $0.004763. Score: 6/6. 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: $0.0048
Wall time: 20s
Human step-ins: 0
Turns: 4

Model usage
Model	Input tok	Output tok	Cost
AClaude Haiku 5.5anthropic/claude-haiku-5.5effort default (no --effort flag) · thinking on	84,434	3,591	$0.0048

Reproduce this run

Use the use case prompt on the use case page.
Same setup: Claude Haiku 5.5 (anthropic/claude-haiku-5.5, effort default (no --effort flag) · thinking on) via Claude Code 2.1.299 (headless -p), cloud.
It counts as a success only if it meets every success criterion: occupancy_days prorated_shares shares_sum_to_bill zero_day_people_excluded owed_totals net_balances
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

[
 {
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  "stop_reason": "end_turn",
  "session_id": "[REDACTED]",
  "total_cost_usd": 0.00476286,
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   "cache_creation_input_tokens": 11170,
   "cache_read_input_tokens": 73256,
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   "output_tokens_details": {
    "thinking_tokens": 1874
   },
   "server_tool_use": {
    "web_search_requests": 0,
    "web_fetch_requests": 0
   },
   "service_tier": "standard",
   "cache_creation": {
    "ephemeral_1h_input_tokens": 11170,
    "ephemeral_5m_input_tokens": 0
   },
   "inference_geo": "global",
   "iterations": [
    {
     "input_tokens": 2,
     "output_tokens": 1431,
     "cache_read_input_tokens": 21152,
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     "cache_creation": {
      "ephemeral_5m_input_tokens": 0,
      "ephemeral_1h_input_tokens": 2557
     },
     "type": "message"
    }
   ],
   "speed": "standard",
   "fallback_credit": null
  },
  "modelUsage": {
   "claude-haiku-5-5": {
    "inputTokens": 8,
    "outputTokens": 3591,
    "cacheReadInputTokens": 73256,
    "cacheCreationInputTokens": 11170,
    "webSearchRequests": 0,
    "costUSD": 0.00476286,
    "contextWindow": 1000000,
    "maxOutputTokens": 128000,
    "thinkingTokens": 1874,
    "canonicalModel": "claude-haiku-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": {
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   "by_type": {}
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  "safety_stops": 0,
  "is_error": false,
  "num_turns": 4,
  "subtype": "success",
  "api_error_status": null,
  "result": "I wrote `out/split.json`. The shares for each bill add up to the bill amount, and the net balances sum to zero.\n\nI read `owed_usd` as each person's total of shares across all bills, and `net_usd` as what they paid minus that total.\n\n| Person | Owed (USD) | Net (USD) |\n|---|---|---|\n| Chen | 555.77 | -104.69 |\n| Femi | 264.58 | -77.51 |\n| Gus | 217.51 | 372.48 |\n| Jun | 514.80 | -190.28 |\n\nI checked the day counts by hand for each bill. For B03-internet, the rounded shares summed to 42.83, so one cent came off Chen's share (tie at 31 days, alphabetical). Chen's share is 15.25 and Jun's is 15.26.\n\nI computed the split with an inline Python script and did not save it, since the run only allows writes under `out/`.",
  "ttft_ms": 1852,
  "type": "result",
  "duration_ms": 19061,
  "uuid": "[REDACTED]",
  "ttft_stream_ms": 1407,
  "time_to_request_ms": 264,
  "first_content_frame_ms": 1407,
  "queued_turn_count": 0,
  "result_index": 0
 }
]