## Summary Implement a field validator in `labkit-go` to enforce logging field standards across GitLab services. This will prevent new deprecated or non-standard logging fields from being introduced into the codebase. ## Background GitLab is standardizing observability fields across all services to improve log correlation and analysis. See the [Observability Field Standardisation design document](https://handbook.gitlab.com/handbook/engineering/architecture/design-documents/observability_field_standardisation/) for full context. ## Proposed Solution Add a runtime field validator to LabKit that: 1. **Defines standard fields** in the labkit-go package 2. **Tracks deprecated field mappings** showing old field to new field relationships 3. **Validates logging fields** automatically during test runs 4. **Reports violations** at the end of test execution ### Components #### 1. Standard Fields Definition - Define standard field constants in the labkit-go package - Add deprecated field mappings #### 2. Field Validator - Validate fields during logging operations - Collect violations during test execution - Report all violations after test suite completes - Fail CI if new violations are introduced (out of scope for this issue) #### 3. Configuration - Allow list: standard fields defined in the package - Any existing violations that are acknowledged and version-controlled in a project's repository should also be "allowed", creating a frozen baseline pattern