Claude Opus 5.5 (effort default (no --effort flag) · thinking on) on Final standings with tie-breaks for a club Swiss tournament (Buchholz Cut-1 with virtual opponents, Sonneborn-Berger, direct encounter)

AClaude Opus 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: $0.17
Wall time: 32s
Human step-ins: 0
Outcome: Pass

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Exact prompt

# Final standings with tie-breaks for a club Swiss tournament `players.csv` (name, rating) and `results.csv` (round, white, black, result; rows in any order) hold a finished event. Write `standings.py` (Python 3 stdlib only) that, run as `python standings.py` in a directory with those two files, writes `standings.csv`. We also run it on other events, so do not hard-code anything. ## Results 1. `result` is `1-0`, `0-1`, `1/2-1/2` (games played over the board), `+-` / `-+` (forfeit: white / black gets 1 point, the other 0; **not** played over the board), or, with `black` empty, `BYE` (white gets 1 point) or `HALF` (white gets 1/2). A player with no row in a round got 0 points that round. R = the highest round number in the file. 2. **Points** = sum of points from all rows. ## Tie-breaks (higher is better at every step) 3. **Buchholz Cut-1 (`bh_cut1`)**: for each round 1..R take a contribution: the opponent's final points if the player played that round **over the board**, otherwise (bye, half bye, forfeit win or loss, absent) the player's **own** final points. Sum all R contributions and subtract the single smallest one. 4. **Sonneborn-Berger (`sb`)**: sum over games played over the board of opponent's final points x points the player scored in that game (1, 1/2 or 0). Unplayed rounds add nothing. 5. Rank by points, then bh_cut1, then sb. 6. **Direct encounter**: players still equal on all of points, bh_cut1 and sb form a group. If the group has 2+ players **and every pair in it played each other over the board** (in some round), order them by points scored in over-the-board games against other group members. Otherwise this step does nothing for the group. 7. Remaining ties: more over-the-board wins (forfeit wins do not count), then higher rating, then name (ascending, plain string order). 8. Use exact arithmetic (all values are multiples of 1/4). ## Output 9. `standings.csv`: header `rank,name,points,bh_cut1,sb,wins`; ranks 1..n without gaps (every player gets a distinct rank); `points` and `bh_cut1` with 1 decimal, `sb` with 2 decimals, `wins` = over-the-board wins as an integer. Every player in `players.csv` is listed. ## Scoring Hidden checks (partial credit = fraction passed; all must pass), each comparing `standings.csv` exactly: `fixture_exact` (this directory's files), `forfeits_and_byes` (1-2, 7), `buchholz_virtual` (3), `sonneborn_berger` (4), `direct_encounter` (6), `final_tiebreaks` (7), `fresh_event_exact` (a freshly generated event). Each run has a 30-second limit.

Forfeits count for points but not for tie-breaks, unplayed rounds use the player's own score, Cut-1 drops one contribution, direct encounter applies only when every pair in a tie group met over the board; hand-made events isolate each rule. 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. fixture_exact 2. forfeits_and_byes 3. buchholz_virtual 4. sonneborn_berger 5. direct_encounter 6. final_tiebreaks 7. fresh_event_exact

Setup notes: Use Case Scout batch 8 case i08-swiss-tiebreak-standings (offline fixture). Prepared with batch8/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-opus-5.5: $0.171443. Score: 7/7. 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: $0.17
Wall time: 32s
Human step-ins: 0
Turns: 6

Model usage
Model	Input tok	Output tok	Cost
AClaude Opus 5.5anthropic/claude-opus-5.5effort default (no --effort flag) · thinking on	123,531	3,410	$0.17

Reproduce this run

Use the use case prompt on the use case page.
Same setup: Claude Opus 5.5 (anthropic/claude-opus-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: 1. fixture_exact 2. forfeits_and_byes 3. buchholz_virtual 4. sonneborn_berger 5. direct_encounter 6. final_tiebreaks 7. fresh_event_exact
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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  "result": "I wrote `standings.py`. Running `python standings.py` in this directory writes `standings.csv` for all 15 players, with Lea Roux first on 5.5 points. It uses only the standard library and nothing about this event is hard-coded.\n\n**How it works:**\n- **Exact numbers:** all arithmetic uses exact fractions, so nothing is rounded until the output is formatted.\n- **Forfeits and byes:** they add points but don't count as over-the-board games. In Buchholz Cut-1 such a round counts the player's own final points, and Sonneborn-Berger skips it.\n- **Buchholz Cut-1:** it covers every round from 1 to the highest round in the file. Rounds where a player has no row also count their own final points.\n- **Direct encounter:** this applies only to players still tied on points, Buchholz Cut-1 and Sonneborn-Berger, and only if every pair in the group played each other over the board. It then orders them by points scored in those games. Otherwise it has no effect for that group.\n- **Last tie-breaks:** over-the-board wins, then higher rating, then name in plain string order. Every player gets a distinct rank.\n\n**Checks:**\n- I hand-checked Hana Ito's row in the fixture output. Their 3.0 points come from three byes, and their Sonneborn-Berger of 0.00 is correct because they lost every game they actually played.\n- On a small made-up event with a forfeit, a draw and a three-way tie on points, I worked out one player's points, Buchholz Cut-1 and Sonneborn-Berger by hand and they matched.\n- **Not tested:** that made-up event never left a tie that the direct-encounter step had to settle, so that path hasn't been run on real data yet.",
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