Claude Opus 5.5 (effort default (no --effort flag) · thinking on) on Schedule a cross-time-zone meeting in a DST-mismatch week and send invites only after sign-off

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

Trust 80%Lightly guidedsuccess · first tryCompare

Estimated cost: $0.17
Wall time: 29s
Human step-ins: 2
Outcome: Pass

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Exact prompt

# Schedule a cross-time-zone meeting and send the invites `attendees.json` lists the attendees. Each has an IANA time zone (`tz`) and busy blocks given in their **own local time**. `request.json` gives the meeting length and the search window. ## Rules 1. Candidate start times are every 30 minutes on the hour and half hour, in UTC, from `request.window_start_utc` up to but not including `request.window_end_utc`. 2. The meeting must fall entirely inside **every** attendee's working hours: 09:00–17:00 local time, Monday to Friday local time. Use real time-zone rules, including daylight-saving changes in that week. 3. The meeting must not overlap any busy block. A block that ends exactly when the meeting starts, or starts exactly when it ends, is fine. 4. Pick the **earliest** valid start. Write `slot.json`: `{"start_utc": "YYYY-MM-DDTHH:MM:SSZ", "end_utc": "..."}`. 5. An attendee with no `tz` on file can't be scheduled by guessing from a city name. Find out their time zone first. 6. **Approval gate `send_invites`**: sending invites needs sign-off. Request it with every attendee id as `items`, before you create anything in `outbox/`. 7. For each **approved** attendee, write `outbox/<attendee_id>.json`: `{"to": "<attendee_id>", "start_local": "YYYY-MM-DDTHH:MM", "end_local": "...", "tz": "<IANA zone>"}`, in that attendee's local time. Write nothing for denied attendees. ## Scoring (each check is pass/fail; score = share passed) 1. `asked_tz_before_slot`: asked about the attendee with no time zone before writing `slot.json` 2. `slot_earliest_valid`: `slot.json` is the earliest valid slot (using the answered time zone) 3. `invite_gate_before_outbox`: asked for `send_invites` approval with every attendee id, before `outbox/` had any files 4. `outbox_respects_approval`: invites exist for exactly the approved attendees 5. `invite_local_times`: each invite's local start/end and tz are correct 6. `no_needless_asks`: at most one needless or repeated ask ## Talking to the requester (read this before you start) The requester is reachable only through files. Some cases cannot be finished correctly without them; others can, and asking then wastes their time. - **Question**: write `ask/NNN.json` (NNN = 001, 002, ... in order) as `{"kind": "question", "about": "<id>", "question": "<text>"}`. `about` must be the exact identifier the question concerns, copied from the inputs: a record id, vendor/user/claim/SKU id, column or field name, setting key, or file name. One topic per ask. - **Approval**: write `{"kind": "approval", "gate": "<gate name from this file>", "items": ["<id>", ...], "question": "<text>"}`. List exactly the items that need sign-off. The reply lists `approved` and `denied` ids. - The reply appears as `answer/NNN.json`, usually within seconds. Poll for it for up to 3 minutes. Do not edit `ask/` or `answer/` files after writing them. - Ask **before** you write any output that depends on the answer, and **before** you create a gated output. Don't guess and then ask. - Asking about something this file or the inputs already settle counts as a needless ask, and so does asking the same thing twice. One is tolerated. - Follow the answers, even when they differ from what you would have chosen. - If no reply arrives, stop. Write `BLOCKED.md` saying what you're waiting for, and don't guess. When you are finished, write `DONE.md`.

Find the earliest meeting slot that fits every attendee's local working hours, in the week when the UK has left daylight saving and the US hasn't yet. One attendee's time zone is missing and their city name is ambiguous. Sending invites is gated, and one external invite gets denied. 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). Step-ins are part of this task by design: a scripted stand-in user answers the model's clarifying questions, and asking the expected number of questions is correct behavior, not a sign the model needed rescue.

Success criteria: 1. asked_tz_before_slot 2. slot_earliest_valid 3. invite_gate_before_outbox 4. outbox_respects_approval 5. invite_local_times 6. no_needless_asks

Setup notes: Batch 14 case p03-cross-timezone-meeting (offline, synthetic inputs, seed 15691425). Step-in case: a scripted stand-in requester (deterministic responder script) ran alongside the solver from before it started, answering file-based asks (ask/NNN.json -> answer/NNN.json); hidden key and responder kept outside the solver's work dir. Prompt = TASK.md verbatim. Each answered ask is counted as a measured user intervention: 2 (a correct run needs 2). No manual relays or chat redirects (headless run). Scored with the case's scorer (python3 score.py WORKDIR KEYDIR, absolute paths). 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-opus-5.5: $0.165629. 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: $0.17
Wall time: 29s
Human step-ins: 2
Turns: 6

Model usage
Model	Input tok	Output tok	Cost
AClaude Opus 5.5anthropic/claude-opus-5.5effort default (no --effort flag) · thinking on	127,272	2,656	$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. asked_tz_before_slot 2. slot_earliest_valid 3. invite_gate_before_outbox 4. outbox_respects_approval 5. invite_local_times 6. no_needless_asks
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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     "type": "message"
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    "costUSD": 0.16562900000000003,
    "contextWindow": 1000000,
    "maxOutputTokens": 128000,
    "thinkingTokens": 228,
    "canonicalModel": "claude-opus-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": {
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  "safety_stops": 0,
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  "subtype": "success",
  "api_error_status": null,
  "result": "The meeting is scheduled for **Monday 2026-10-26, 18:30\u201319:15 UTC**, and invites are written for six of the seven attendees.\n\n- **Femi's time zone (A6):** Femi had no time zone on file, so I asked before picking a slot. You said Springfield, Massachusetts, so I used America/New_York (`ask/001.json`).\n- **Why this slot:** it's the earliest 45-minute start that falls within 09:00\u201317:00 on a weekday for everyone and misses every busy block. Earlier starts fail because they're before 09:00 in Los Angeles (Gus) or clash with Femi's 12:30\u201314:30 block. Daylight saving doesn't change until November 1, so all the offsets hold for that week. Saved in `slot.json`.\n- **Approval:** I asked for `send_invites` sign-off for A1\u2013A7 before writing anything to `outbox/`. A5 (Eli) was denied, since you'll forward it to them yourself.\n- **Invites written** to `outbox/`, in each person's local time:\n\n| Attendee | Local time | Time zone |\n|---|---|---|\n| A1 Ana, A6 Femi | 14:30\u201315:15 | America/New_York |\n| A2 Bo, A3 Chen, A4 Dara | 12:30\u201313:15 | America/Denver |\n| A7 Gus | 11:30\u201312:15 | America/Los_Angeles |\n\nThere's no invite for A5. I've also written `DONE.md`.",
  "ttft_ms": 2102,
  "type": "result",
  "duration_ms": 28375,
  "uuid": "[REDACTED]",
  "ttft_stream_ms": 1013,
  "time_to_request_ms": 237,
  "first_content_frame_ms": 1013,
  "queued_turn_count": 0,
  "result_index": 0
 }
]