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  "startedAt": "2026-10-23T14:17:40.108Z",
  "prompt": "Implement billingDates() in src/schedule.js. The spec is in the comment above it.",
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      "finalMessage": "I implemented `billingDates()` in `src/schedule.js`, but I haven't run it. The command to run my quick check script needed approval, and I didn't retry it. I also didn't run any existing tests.\n\nIt follows the spec in the comment:\n- **Weekly:** bills every `interval` weeks from the start date.\n- **Monthly:** each date is computed from the start date rather than from the previous one. That's how Jan 31 → Feb 28 (or 29 in a leap year) → Mar 31 comes out right.\n- **Stopping:** it stops at `count`, at `until` (inclusive), or at whichever comes first.\n- **Skips:** skipped dates are left out and don't count toward `count`.\n- **Errors:** it throws a `RangeError` in every case the spec lists. Impossible dates like `2024-02-30` are rejected.\n\nI also made it throw a `RangeError` if `rule` itself is missing, which the spec doesn't mention.\n\nI wrote a small check script at `/tmp/t.mjs`. It covers Jan 31 monthly, weekly with `until` and a skip, a 13-month interval, and an invalid date. If you approve `node /tmp/t.mjs`, I'll run it.",
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      "finalMessage": "I implemented `billingDates()` in `src/schedule.js` to match the spec, but I haven't run it. My test script was blocked: the first shell command was rejected, the file write failed because `/tmp/t.mjs` already existed, and `node` needed approval.\n\n- **Monthly billing:** Each date is computed from the start date (start month plus `interval × k`, with the day capped to that month's length). Jan 31 gives Feb 28/29, then Mar 31, with no drift.\n- **Weekly billing:** Each date is the start plus `7 × interval × k` days, using UTC arithmetic.\n- **Skipped dates:** Skipped dates are left out of the result and don't count toward `count`.\n- **Stopping:** The loop stops at `count`, or at the first date after `until`, whichever comes first.\n- **Validation:** It throws a `RangeError` for the cases the spec lists. It checks that dates are real calendar dates, including leap days.\n- **Year limit:** I also added a stop once the year passes 9999, which the spec doesn't mention. It keeps the output in 'YYYY-MM-DD' form.\n\nIf you want me to check it, approve running `node` and I'll try a few cases: Jan 31 monthly, a bi-weekly run with `until` and `skip`, and an invalid date.",
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      "finalMessage": "I've implemented `billingDates()` in `src/schedule.js`, but I haven't run it. My test script needs approval to run, and I haven't received it.\n\nWhat it does, following the spec comment:\n- **Weekly:** it steps `7 × interval` days from the start.\n- **Monthly:** it keeps the start date's day of the month. In a shorter month it uses that month's last day, so Jan 31 gives Feb 28 or 29 and then Mar 31.\n- **Skipped dates:** it leaves them out, and they don't count toward `count`.\n- **Stopping:** it stops at `count`, or at the first date after `until`, whichever comes first.\n- **Validation:** it throws a `RangeError` in each case the spec lists:\n  - neither `count` nor `until` is given\n  - `interval` or `count` isn't a positive integer\n  - `every` isn't `'week'` or `'month'`\n  - `start` or `until` isn't a real `YYYY-MM-DD` date, such as `2023-02-29`\n\nThe check script is `/tmp/bd_check_8wdti2.mjs`. It tries month-end clamping, biweekly with `until` and `skip`, a skipped first date, and an invalid date. If you approve `node /tmp/bd_check_8wdti2.mjs`, I'll run it and report the output.",
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      "finalMessage": "I implemented `billingDates()` in `src/schedule.js`, and the tests pass (5 of 5, including the one that was already there). I added four tests to `tests/schedule.test.js` covering:\n\n- month-end clamping, including a leap year\n- week and month intervals, `until`, and `skip`\n- an `until` earlier than `start`\n- invalid inputs\n\n- **Month-end clamping:** Each monthly date is worked out from the original start day rather than from the previous date. Jan 31 gives Feb 28, then Mar 31, instead of drifting to the 28th.\n- **Skipped dates:** They are left out of the result and don't count toward `count`. A skipped date does still count as a cycle, so the next date stays on its normal day.\n- **`count` and `until` together:** The result stops at whichever limit comes first. An `until` earlier than `start` returns `[]`.\n- **Validation:** It throws `RangeError` for each case the spec lists. That includes real-date checks, so `2026-02-30` and `2026-1-01` are rejected.\n\nThe spec doesn't cover these cases, so I chose:\n\n- A missing or non-object `rule` throws `RangeError`.\n- `null` counts as \"not given\" for `count` and `until`.\n- A schedule that runs past year 9999 throws `RangeError` instead of returning truncated results.\n- Entries in `skip` aren't validated. A malformed one just never matches anything.\n\nI haven't committed anything.",
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      "finalMessage": "I implemented `billingDates()` in `src/schedule.js`, and all 7 tests pass. That includes six new ones I added to `tests/schedule.test.js`.\n\n- **Month-end dates:** each date is worked out from the start date, not from the previous date. So Jan 31 gives Feb 28, then Mar 31, with no drift. A Feb 29 start billed every 12 months gives Feb 28 in non-leap years.\n- **Weeks:** dates step by 7 × `interval` days and roll over year boundaries correctly.\n- **`skip`:** skipped dates are left out and don't count toward `count`.\n- **Stopping:** the loop ends at `count`, or at the first date after `until`. If `until` is before the start, you get an empty array.\n- **Errors:** it throws a `RangeError` for all the cases in the spec. It also throws if `rule` isn't an object or `skip` isn't an array, which the spec doesn't mention.\n\n**Two choices of mine:**\n- **Year 9999:** a schedule stops at year 9999 instead of producing five-digit years.\n- **`skip` entries:** entries are not validated. One in the wrong format simply never matches a billing date.\n\nThe new tests cover month-end clamping, a weekly schedule across a year boundary with `skip`, the `count`/`until` interaction, and the error cases.",
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      "finalMessage": "I implemented `billingDates()` in `src/schedule.js`, and all 9 tests pass, including the 8 I added.\n\n- **Monthly billing:** each date is worked out from the start date, not from the previous date. The day is the start day, or the month's last day if the month is shorter. Jan 31 gives Feb 28, then Mar 31. In a leap year it gives Feb 29. `interval` works across year boundaries.\n- **Weekly billing:** it adds `7 × interval × i` days to the start date. Month and year rollovers are handled by `Date`.\n- **Stopping:** the loop ends at `count` results or when a date passes `until` (inclusive), whichever comes first. If `until` is before `start`, the result is an empty array.\n- **Skipped dates:** a skipped date is left out and doesn't count toward `count`.\n- **Validation:** it throws a `RangeError` in each case the spec lists. `interval` defaults to 1 and `skip` to `[]`. Dates must match `YYYY-MM-DD` exactly and be real calendar dates, so `2027-02-29` and `2026-1-15` are rejected.\n- **Untested:** the tests don't cover years before 1000 or after 9999.\n\nThe new tests in `tests/schedule.test.js` cover the month-end and leap-year cases, intervals, `until` and `count` together, skips, and the invalid inputs.\n\nI didn't commit anything.",
      "diffstat": "src/schedule.js        | 60 +++++++++++++++++++++++++++++++++++++++++++++++++-\n tests/schedule.test.js | 47 +++++++++++++++++++++++++++++++++++++++\n 2 files changed, 106 insertions(+), 1 deletion(-)"
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