feat: add onion architecture preset to boundary rules

[carlos-alm]

Summary

• Add onion preset with layers: domain-model → domain-services → application → infrastructure
• Enforces inward-only dependency direction, same as the other presets
• Completes the four most popular layered architecture patterns: hexagonal, layered, clean, onion

Test plan

• Unit test updated to verify all four presets
• All 32 boundary tests pass

[claude]

Claude finished @carlos-alm's task —— View job

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PR Review: Onion Architecture Preset

Todo List

• Read and understand the modified files
• Analyze root cause - what problem this solves
• Check implementation against existing patterns
• Verify test integrity and coverage
• Assess code quality and potential issues
• Provide final rating and recommendation

Root Cause Analysis

Problem Being Solved: The PR adds support for onion architecture, completing the four most popular layered architecture patterns (hexagonal, layered, clean, onion). This addresses a gap in architectural preset coverage for teams using onion architecture.

Why This Approach: The implementation follows the exact same pattern as the existing three presets, maintaining consistency in the codebase. The onion layers (domain-model → domain-services → application → infrastructure) follow standard onion architecture conventions.

Risk Assessment: Very low risk. This is a pure additive change with no modifications to existing functionality.

Implementation Analysis

Positive aspects:

• ✅ Consistent pattern: Follows exact same structure as hexagonal, layered, and clean presets
• ✅ Correct layer ordering: Inner-to-outer layers match onion architecture principles
• ✅ Minimal change: Only 6 additions, 1 deletion - focused scope
• ✅ Test coverage: Updated test from "all three presets" to "all four presets" with explicit assertion for onion
• ✅ Standard naming: Uses conventional onion layer names (domain-model, domain-services, etc.)

Code quality:

• Implementation at src/boundaries.js:61-64 is identical in structure to other presets
• Test update at tests/unit/boundaries.test.js:187-191 properly validates the new preset exists
• All existing functionality remains unchanged
• The generatePresetRules() function will automatically work with the new preset

Critical Concerns

None identified. This is a straightforward, well-implemented addition.

Minor observations:

• Layer naming uses kebab-case (domain-model) which is consistent with existing patterns
• The description reuses "Inward-only dependency direction" which accurately describes the behavior
• The test ensures all four presets have valid layers arrays

Final Recommendation

• Rating: ⭐⭐⭐⭐☆ (4/5)
• Action: APPROVE
• Reasoning: Clean implementation that follows established patterns exactly, minimal scope, appropriate test coverage, and completes a logical set of architectural presets. This is exactly the kind of straightforward, focused change that should be approved quickly.

The only reason it's not 5 stars is that it's a simple addition rather than solving a complex problem, but it's executed very well.

[greptile-apps]

Greptile Summary

Adds the onion architecture preset to complete support for the four most popular layered architecture patterns (hexagonal, layered, clean, and onion).

• Added onion preset with four layers: domain-model → domain-services → application → infrastructure
• Enforces inward-only dependencies, consistent with other presets
• Updated test to verify all four presets are defined

Confidence Score: 5/5

• This PR is safe to merge with minimal risk
• Simple additive change that follows existing patterns exactly. The new preset uses the same structure as the three existing presets, and the implementation correctly integrates with the existing generatePresetRules function. Test coverage is adequate and all 32 boundary tests pass according to the PR description.
• No files require special attention

Important Files Changed

Filename	Overview
src/boundaries.js	Added onion preset with correct layer ordering: domain-model → domain-services → application → infrastructure
tests/unit/boundaries.test.js	Updated test assertion from three to four presets, added check for onion preset

_{Last reviewed commit: a8c6fb9}

[greptile-apps]

_{2 files reviewed, no comments}

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