Journey validation

The form and the API share the same rules. Typical failures:

• Origin or destination country is required. Pick the country again if autocomplete left it blank. This happens most often on the first submit after searching a city.
• City and country do not match. Bangkok is not in Vietnam. Pick the city from the list instead of typing a mismatched pair.
• Invalid country. Use a country from the list (name or ISO code).
• Arrival before departure. Check dates and local times. A westbound flight can land “earlier” on the clock, but the timeline still has to be possible after timezones.
• Journey too long. A multi-day “flight” usually means wrong dates or a stopover that should be its own journey.
• Future departure on Free. Past journeys only. Upgrade the ledger to save a future trip.
• Duplicate warning. Logging a very similar journey again warns before it inserts. Confirm you meant a second record.

Multi-leg edits replace every leg. Read the journey back before you patch the route, or you will drop per-leg details.