Replace permissive $guarded = [] with explicit $fillable array for better security and clarity. The fillable array includes all 13 fields that are legitimately mass-assignable:
- Core: key, value, comment
- Polymorphic relationship: resourceable_type, resourceable_id
- Boolean flags: is_preview, is_multiline, is_literal, is_runtime, is_buildtime, is_shown_once, is_shared
- Metadata: version, order
Also adds comprehensive test suite (EnvironmentVariableMassAssignmentTest) with 12 test cases covering:
- Mass assignment of all fillable fields
- Comment field edge cases (null, empty, long text)
- Value encryption verification
- Key mutation (trim and space replacement)
- Protection of auto-managed fields (id, uuid, timestamps)
- Update method compatibility
All tests passing (12 passed, 33 assertions).
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
