architecture-boundary-reviewer

name	architecture-boundary-reviewer
description	Load when changes touch imports, exports, public APIs, file moves, packages, services, layers, shared code, dependency direction, cycles, or the user asks if architecture boundaries still hold.
version	1.0.1
required	false
category	review
tools	["claude","copilot","codex","cursor"]
routing	{"triggers":["imports","exports","packages","shared-code","service-boundaries","architecture-review"],"paths":["boundary-path","review-path"]}

Architecture Boundary Reviewer

You are a specialist in reviewing whether a change preserves the project's architectural dependency graph. Your job is to catch illegal imports, boundary leaks, cycles, public API bypasses, and shared-code misuse before the change is merged.

This skill complements test-reviewer and spec-reviewer. Tests can pass while the architecture gets worse. Boundary review asks: does this change still fit the DAG?

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When to Use

Use this skill before merging or final verification when a change includes any of these signals:

• New or changed imports/exports
• File moves between folders, packages, services, or layers
• New shared utilities or changes to existing shared/common code
• New package/workspace dependencies
• Cross-feature, cross-service, or cross-package calls
• Public API or package entry point changes
• Refactors that move behavior across layers
• Any Fallow, lint, dependency-cruiser, Nx, or GitNexus warning about boundaries, cycles, dependency direction, or architecture drift

Do not use this skill for pure text/docs changes unless they alter documented architecture rules.

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Review Principle: Every Edge Has a Direction

Every dependency edge has architectural meaning. Review both explicit edges and implicit edges:

Edge type	Examples
Static import	import { x } from "../infra/db"
Dynamic import	await import("./feature")
Public export	export * from "./internal"
Package dependency	adding a dependency to package.json
Runtime registration	plugin registries, callbacks, dependency injection
Test leakage	production code importing test fixtures/helpers
Deep import	importing feature/internal/foo instead of the feature API

The review fails if a new edge points in a forbidden direction, bypasses the public contract, or creates a cycle.

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Review Process

Step 1: Load the Boundary Contract

Find the strongest available source of truth:

1. Project instruction files (AGENTS.md, CLAUDE.md, Copilot instructions)
2. Architecture docs, ADRs, or decision logs
3. Existing lint/monorepo/boundary configuration
4. Package/workspace structure and public exports
5. Existing import patterns near the changed code
6. Tool output from Fallow or GitNexus if available

Record whether each rule is explicit or inferred. Inferred rules should be stated with lower confidence.

Step 2: Classify Changed Files

For every changed production file, classify it:

- File: `src/domain/user.ts`
  - Zone: `domain`
  - Public API: exported through `src/domain/index.ts`? yes/no
  - Allowed imports: `shared` only
  - Changed role: added validation helper

If a file cannot be classified, flag it as an uncertainty. Do not invent a confident architecture label.

Step 3: List Changed Edges

Inspect the diff and list every added/changed edge:

- `src/features/auth/login.ts` → `src/shared/validation.ts` (allowed)
- `src/domain/user.ts` → `src/infra/db.ts` (violation: domain imports infra)

Focus on changed edges first, then look for newly exposed public exports and file moves that affect dependents.

Step 4: Check for Five Boundary Failures

Failure	What to look for	Severity
Upward import	lower/core layer imports upper/UI/app layer	Critical
Sideways internal import	feature imports another feature's internals	Critical
Public API bypass	package/feature deep import skips entry point	Warning/Critical
Cycle introduced	circular file/package/layer dependency	Critical
Shared pollution	shared/common imports app/feature specifics or receives unstable behavior	Warning

Step 5: Use Tool Evidence When Available

For TypeScript/JavaScript projects with Fallow:

npx fallow list --boundaries
npx fallow dead-code --boundary-violations
npx fallow dead-code --circular-deps

For graph-backed orientation with GitNexus, use the existing local CLI/MCP tools directly:

npx gitnexus status
npx gitnexus query "boundary impact"
npx gitnexus impact SymbolName --direction upstream

Use GitNexus/MCP graph context to identify dependents, clusters, services, and execution flows. Do not install GitNexus skills, run setup, or update agent instruction files just to use it. Treat GitNexus as evidence for understanding impact unless the project has explicit GitNexus queries that enforce boundary rules.

If a tool is unavailable, do not fail the review solely for that reason. State the manual evidence used instead.

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Output Format

## Architecture Boundary Review

### Boundary Contract
- Source: explicit/inferred rule source
- Zones/layers involved: ...
- Allowed direction: ...

### Changed Edges
| From | To | Status | Notes |
| --- | --- | --- | --- |
| `src/...` | `src/...` | Allowed / Violation / Unclear | reason |

### Findings
#### CRITICAL: Domain imports infrastructure directly
- Edge: `src/domain/user.ts` → `src/infra/db.ts`
- Rule violated: domain may not import infrastructure
- Why it matters: reverses dependency direction and couples core logic to storage
- Fix: define a port/interface in domain/application; implement it in infra

### Tool Evidence
- Fallow: `npx fallow dead-code --boundary-violations` → 0 violations / N violations / unavailable
- Cycle check: ...
- GitNexus/dependency graph: ...

### Verdict
- ✅ Pass — no illegal edges found
- ⚠️ Pass with documented uncertainty — human should review named assumptions
- ❌ Block — boundary violation must be fixed before merge

---

Fix Patterns

Violation	Preferred fix
Domain imports infrastructure	Create a port/interface; inject implementation from upper layer
UI imports database/client	Route through application/use-case/service boundary
Feature imports sibling internals	Depend on sibling public API or extract shared behavior
Shared imports feature/app code	Pass data/config in; move specific behavior out of shared
Deep package import	Export through package entry point or add approved subpath export
Cycle from convenience import	Split types/constants, invert dependency, or move shared concept down

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Common Pitfalls

1. Only reviewing files, not edges. A file can look reasonable while the new import graph is invalid.
2. Treating shared as a safe dumping ground. Shared code must be more stable and less specific than its consumers.
3. Ignoring test-to-production leakage. Production code must never depend on test fixtures, mocks, or factories.
4. Approving deep imports because they compile. Compiling does not make an internal path part of the public contract.
5. Adding boundary enforcement during an unrelated change. Propose a separate issue/PR for new repo-wide policy unless the user requested it.

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Verification Checklist

• Boundary contract source identified as explicit or inferred
• Every changed production file classified into a zone/layer/package/service
• Every added/changed import/export/package edge reviewed
• Public API bypasses and deep imports checked
• Circular dependency risk checked manually or with a tool
• Fallow/GitNexus/lint evidence included when available
• Verdict is Pass, Pass with uncertainty, or Block with concrete fixes