OpenHistoricalMap/issues

Warn when end date precedes start date

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#1,333 opened on Apr 9, 2026

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good first issueiD

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Description

iD should have a validator rule that ensures a feature’s end_date=* comes after its start_date=*, since this prevents any time-enabled renderer or query from exposing the feature at all. This would complement the existing validator warning for mismatched basic and EDTF dates.

The new validator rule should account for different levels of granularity in the start_date=* and end_date=* tags. For example, start_date=2000 end_date=2000-03-01 is not an error, and neither is start_date=2000-03-01 end_date=2000.

Contributor guide

Research direction
Examine the existing mismatched dates validator module (modules/validations/mismatched dates.js) to understand the validator structure and pattern. Then create a new validator that parses start date and end date values, compares them with granularity awareness, and adds a warning if the end date precedes the start date.
Tech stack
javascript
Domain
testing
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
JavaScript
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70