Recurrence: MONTHLY/YEARLY silently skip short months / non-leap years (month-end policy) #12

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opened 2026-06-05 10:26:18 +00:00 by victor · 0 comments

victor commented

2026-06-05 10:26:18 +00:00

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When BYMONTHDAY is absent, the target day defaults to anchor.day() (src/core/recurrence.rs:240,274). NaiveDate::from_ymd_opt returns None for invalid days and the loop just advances, skipping that month/year entirely.

Consequences:

Anchor Jan 31, FREQ=MONTHLY → next after Jan 31 is Mar 31 (February skipped), not Feb 28.
Anchor Feb 29 2024, FREQ=YEARLY → next is Feb 29 2028 (2025-27 skipped).

This is inconsistent with apply_snap DayOfMonth, which clamps to month-end (recurrence.rs:63-67).

Decision needed (spec): clamp the target day to the last day of the month (recommended — conventional "monthly on the 31st" = month-end, and consistent with the snap behavior) vs. the current skip. REQUIREMENTS §7 should state the chosen policy. Then implement + test the Jan 31 and Feb 29 cases.

Found in review.

When BYMONTHDAY is absent, the target day defaults to `anchor.day()` (src/core/recurrence.rs:240,274). `NaiveDate::from_ymd_opt` returns None for invalid days and the loop just advances, **skipping** that month/year entirely. **Consequences:** - Anchor Jan 31, `FREQ=MONTHLY` → next after Jan 31 is **Mar 31** (February skipped), not Feb 28. - Anchor Feb 29 2024, `FREQ=YEARLY` → next is **Feb 29 2028** (2025-27 skipped). This is inconsistent with `apply_snap` `DayOfMonth`, which **clamps** to month-end (recurrence.rs:63-67). **Decision needed (spec):** clamp the target day to the last day of the month (recommended — conventional "monthly on the 31st" = month-end, and consistent with the snap behavior) vs. the current skip. REQUIREMENTS §7 should state the chosen policy. Then implement + test the Jan 31 and Feb 29 cases. Found in review.

victor closed this issue

2026-06-05 10:42:13 +00:00

victor referenced this issue from a commit

2026-06-05 17:42:26 +00:00

Pick earliest BYMONTHDAY and honor all values in YEARLY recurrence

victor referenced this issue from a commit

2026-06-05 17:42:26 +00:00

Clamp month-end recurrence instead of skipping short months