Make saved ID read-only and add tests

[stefan-burke]

Summary

• When UNIT_BADGES is enabled, the saved unit ID becomes read-only after creation.
• Adds UI, controller, and test coverage to ensure the badge ID cannot be changed via UI or requests.

Changes

UI

• app/views/units/_form.html.erb
  • If UNIT_BADGES is enabled:
    • Existing (persisted) units display the ID in a read-only format on the form.
    • New units display an editable ID field (creation flow).

Backend

• app/controllers/units_controller.rb
  • Permit :id for create actions only when UNIT_BADGES is enabled. Creation actions include create and create_from_inspection.
  • This ensures the ID can be supplied during creation, but not updated later.

Tests

• spec/features/units/unit_badges_spec.rb

  • Added scenarios for ID immutability on edit:
    • ID field is not present on the edit form.
    • ID remains unchanged when editing other fields.
    • Badge ID is shown on the edit page in display format.

• spec/requests/units/units_spec.rb

  • Added request specs for ID immutability:
    • Patching a unit with a new ID does not update the original ID.
    • ID parameter is ignored in update requests in favor of existing ID.

Test plan

• Run the unit badge tests:
  • bundle exec rspec spec/features/units/unit_badges_spec.rb
  • bundle exec rspec spec/requests/units/units_spec.rb
• Verify:
  • On edit, the ID is displayed read-only when UNIT_BADGES is enabled.
  • Creating a new unit allows setting an ID when UNIT_BADGES is enabled.
  • Updating a unit cannot change its ID, while other attributes update normally.

Notes

• The new behavior is gated by the UNIT_BADGES environment variable. Tests set and unset this flag to validate both scenarios. Ensure CI runs with UNIT_BADGES enabled where coverage is required.

🌿 Generated by Terry

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📎 Task: https://www.terragonlabs.com/task/fb797c38-78b3-4192-9cbf-c8e6f809b5fe