Repair DST Recurrence Scheduling Bugs

The problem

Recurring schedules often break during daylight-saving time transitions, leading to skipped tasks, double executions, or incorrect wall-clock alignment. These bugs are notoriously difficult to debug because they involve complex interactions between IANA time zones, UTC normalization, and retry logic.

What it does

• Identifies inconsistencies in wall-clock intent versus UTC instant storage across the codebase.
• Patches logic for DST gaps (non-existent times) and folds (ambiguous duplicate times).
• Standardizes identity and state ownership for recurring tasks to prevent race conditions.
• Implements deterministic local fixtures and time-warping tests to verify fixes.
• Refactors validation logic to catch scheduling errors before irreversible state mutations.

Why this beats prompting it yourself

General-purpose prompts often miss edge cases like tzdata updates or the specific "missed-run" policies required for business logic. This skill follows a strict protocol to map trust boundaries and state ownership, ensuring that fixes don't just "look right" but are architecturally sound and verifiable through local regression tests.

Use cases

• Fixing cron jobs that fire twice or zero times during a DST transition.
• Correcting calendar event offsets after a system-level IANA time-zone database update.
• Ensuring retry and catch-up policies respect the user's original local time intent.
• Adding deterministic test suites for scheduling logic without using brittle sleep commands.

Known limitations

This skill cannot access production services or live secrets. It is designed for repository-level logic repairs and local test fixtures only.