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testland/dst-transition-reference

Pure-reference catalog of Daylight Saving Time (DST) transition patterns and their canonical bug classes. Covers the spring-forward (skipped hour: 02:00 → 03:00 local) and fall-back (repeated hour: 02:00 → 01:00 local) transitions, the historical irregularity of DST (different jurisdictions, transitions on different dates, some regions abolish DST or never adopted it), the IANA timezone database (tz / Olson DB) as the canonical source, and the testable behaviors DST creates (duplicate / missing local timestamps, cron jobs that fire 0 or 2 times, billing periods that miss / double-count, recurring meetings on transition days). Per-jurisdiction DST-rule tables, refreshable per-region test-data fixtures, and the leap-second reference (23:59:60 insertion, time_t stalls, leap-smear vs step, monotonic-clock fixes) live in references/. Use when designing or auditing time-handling code or test cases, or when auditing leap-second assumptions.

68

Quality

86%

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SecuritybySnyk

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Overview
Quality
Evals
Security
Files

Quality

Content

78%Weight 40%Scale 1-5

Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.

A well-structured reference skill body: dense and domain-specific with concrete test recipes and clean progressive disclosure into real bundle files. The main gaps are minor verbosity in the overview and the absence of copy-paste executable assertion code, which hold conciseness and actionability just below the top anchor.

Suggestions

Add a short copy-paste assertion snippet (e.g. Python zoneinfo + pytest) under the worked example so the test recipe is fully executable, not just described.

Trim the Overview paragraph to avoid restating the frontmatter description, and let the 'How to use' and 'DST mechanics' sections carry the framing.

Make the 'How to use' sequence an explicit validate-then-proceed loop (e.g. 'assert the documented result; only then repeat for fall-back') to surface the checkpoint already implied.

DimensionReasoningScore

Conciseness

Dense, reference-oriented body that mostly assumes Claude's competence and avoids explaining basic concepts, but the Overview and some prose repeat what the frontmatter already states and could be trimmed.

4 / 5

Actionability

Highly concrete test recipes with specific timestamps (2026-03-08 02:30 America/New_York), a library-behaviour table, and a worked assertion example, but it stops short of copy-paste executable code blocks for the assertions.

4 / 5

Workflow Clarity

The 'How to use this reference' 4-step sequence and worked example are clearly ordered with an implicit assert-checkpoint, but validation feedback loops are framed as 'assert in your tests' rather than explicit validate-then-proceed gates.

4 / 5

Progressive Disclosure

Clear overview body with well-signaled, one-level-deep markdown links to the three real references/ files (jurisdictions-and-fixtures, leap-seconds, smear-strategies-and-history); deep material is appropriately split out and easy to navigate.

5 / 5

Total

17

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20

Passed

Description

87%Weight 40%Scale 1-5

Based on the skill's description, can an agent find and select it at the right time? Clear, specific descriptions lead to better discovery.

A strong, specific reference-skill description that clearly states both what it catalogs and when to use it, with good natural trigger terms. Slightly verbose in its enumeration of covered items, which keeps specificity and trigger quality just below the top anchor.

DimensionReasoningScore

Specificity

Lists many concrete catalog items (spring-forward skipped hour, fall-back repeated hour, IANA tz/Olson DB, cron fires 0/2x, billing double-count, leap-second 23:59:60 insertion) but the 'covers ...' enumeration is somewhat padded rather than discrete actions.

4 / 5

Completeness

Explicitly answers both 'what' (pure-reference catalog of DST transition patterns and canonical bug classes, covers ...) and 'when' ('Use when designing or auditing time-handling code or test cases, or when auditing leap-second assumptions') with concrete trigger phrases.

5 / 5

Trigger Term Quality

Strong natural keywords (DST, Daylight Saving Time, spring-forward, fall-back, time-handling code, test cases, leap-second) with synonym coverage, but a few common user phrases like 'timezone bugs' or 'scheduled job ran twice' are absent.

4 / 5

Distinctiveness Conflict Risk

Occupies a clear niche (DST transition + leap-second reference) with distinct, specific triggers and minimal overlap risk with other skills.

5 / 5

Total

18

/

20

Passed

Validation

100%

Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.

Validation16 / 16 Passed

Validation for skill structure

No warnings or errors.

Reviewed

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