TO1 (2026) PR06 - Import Layer Fixture support for non-slider relations

[rhodges]

PR06 Summary

Overview

This PR extends fixture import execution to support non-slider layer relationships and related records while preserving UUID-first identity and second-pass relation resolution.

What this PR adds

• Import support for related layer records:
  • AttributeInfo rows
  • LookupInfo rows
  • Companionship relationships
• Import support for specific layer subtype rows linked to base Layer:
  • LayerWMS
  • LayerArcREST
  • LayerXYZ
  • LayerArcFeatureService
  • LayerVector
• UUID-based relation resolution for second pass:
  • Layer attribute_fields relations resolve by UUID
  • Companionship owner and companions resolve by UUID
  • Specific layer subtype layer foreign keys resolve by UUID
  • Vector lookup_table relations resolve by UUID
• Companion merge behavior for duplicate companionship inputs on the same owner layer:
  • Reuse the first Companionship row by owner layer
  • Add only non-duplicate companions from later rows
  • Avoid duplicate companion links on re-import

Files changed

• fixture_import.py
• test_fixture_import.py

Test coverage included in PR06

• AttributeInfo UUID-match updates existing rows.
• LookupInfo source_pk collision with different UUID creates a new row.
• Layer attribute_fields second-pass relation resolution by UUID.
• Companionship relation resolution by UUID.
• Specific layer subtype row creation/linkage for all targeted subtype models.
• Vector lookup_table relation resolution by UUID.
• Companionship duplicate-input merge behavior for same owner layer.

Validation

• All PR06 tests are passing (as reported): 14/14.

Scope notes

• Medium-risk hardening items discussed during review were intentionally deferred by scope decision.
• This PR focuses on execution completeness for PR06 import behaviors only.