# Implementation Report — capturedAt DateTimeOffset (Cycle 13)

**Cycle**: 13
**Tasks**: AZ-1126
**Date**: 2026-06-26

## Summary

Migrated `UavTileMetadata.CapturedAt` from `DateTime` to `DateTimeOffset` with a strict JSON converter requiring explicit UTC offsets. Closes security finding F-AZ810-2.

## Changes

- `UtcOffsetRequiredDateTimeOffsetConverter` rejects offset-less ISO-8601 strings at deserialization
- FluentValidation freshness rules and quality gate use `UtcDateTime` without `DateTimeKind` branching
- `UavUploadValidationFilter` propagates `JsonException.Message` for metadata parse failures
- Contract `uav-tile-upload.md` 1.2.0 → 1.2.1

## Test Evidence

- Unit: `UtcOffsetRequiredDateTimeOffsetConverterTests`, updated UAV validator/gate/handler tests
- Integration: `UavUploadValidationTests.ItemCapturedAtOffsetLess_Returns400`
- Full suite: `./scripts/run-tests.sh` passed (mode=full)

## Handoff

Full test suite already executed in Step 10; Step 11 (Run Tests) may treat this as pre-verified per implement skill Step 16 handoff.
