{"slug":"boundaries","title":"boundaries","summary":"Analyze Phoenix context boundaries and module coupling via mix xref. Use when checking cross-context calls, validating dependencies, before splitting modules, or reviewing architecture.","platform":"Claude","tags":[],"authorName":"LLM Mart","authorSlug":"llm-mart","score":0,"source":"github","price":null,"verified":false,"createdAt":"2026-10-04T15:14:09.756995Z","repo":{"url":"https://github.com/oliver-kriska/claude-elixir-phoenix","stars":560,"forks":44,"license":"MIT","updatedAt":"2026-10-02T04:11:38Z"},"bodyHtml":"
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name: boundaries\ndescription: Analyze Phoenix context boundaries and module coupling via mix xref. Use when checking cross-context calls, validating dependencies, before splitting modules, or reviewing architecture.\neffort: medium\nargument-hint: \"[--assess|--fix]\"

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Phoenix Context Boundary Validation

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Analyze module dependencies to ensure clean context separation and proper architectural boundaries.

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Usage

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/phx:boundaries              # Check for violations\n/phx:boundaries --assess     # Score context health (0-100)\n/phx:boundaries --fix        # Suggest fixes for violations\n
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--assess Mode: Context Health Score

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Evaluate overall boundary health with a quantified score.

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Metrics Calculated

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MetricHealthy RangeRed FlagWeight
Modules per context3-15>20 or <220%
Public API surface5-30 funcs>40 funcs15%
Fan-out (contexts called)1-4>620%
Fan-in (called by contexts)1-6>1015%
Circular dependencies0>015%
Boundary violations0>015%
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Commands for Assessment

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Use Glob to count .ex files per context directory under lib/my_app/*/.\nUse Grep to count public function definitions per context file under lib/my_app/*.ex.\nRun mix xref graph --format stats for dependency analysis.\nRun mix xref graph --format cycles --label compile for compile-time circular dependencies.

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Output Format

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## Context Health Assessment\n\n### Overall Score: 82/100 (Good)\n\n| Context | Modules | API | Fan-Out | Fan-In | Score |\n|---------|---------|-----|---------|--------|-------|\n| Accounts | 5 | 12 | 2 | 4 | 95 |\n| Orders | 18 | 45 | 8 | 3 | 62 |\n| Shared | 2 | 8 | 0 | 12 | 78 |\n\n### Issues Found\n\n1. **Orders** - Too large (18 modules, 45 funcs)\n   - Consider: Extract Fulfillment, Invoicing sub-contexts\n\n2. **Orders** - High fan-out (8 contexts)\n   - Consider: Review if all dependencies necessary\n\n### Recommendations\n\n- Split Orders into Orders + Fulfillment\n- Review Accounts ← Billing dependency\n
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Iron Laws - Never Violate These

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  1. Controllers call only contexts - No direct Repo access from web layer
    2. \n
  2. Schemas are pure data - No side effects, no Repo calls in schema modules
    3. \n
  3. Contexts own their schemas - Don't import schemas from other contexts
    4. \n
  4. Explicit dependencies only - Cross-context calls must be intentional
    5. \n
  5. DO NOT refactor context boundaries without running mix xref first — Refactoring without dependency data creates new violations; always map the dependency graph before moving modules
    6. \n
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Dependency Rules

\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
LayerCan CallCannot Call
ControllersContexts, Plug, ConnRepo, Schemas directly
LiveViewsContexts, Components, PubSubRepo, Schemas directly
ContextsOwn schemas, Repo, other contextsWeb layer modules
SchemasEcto types, validationsContexts, Repo
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Analysis Commands

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Check Compile Dependencies

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Run mix xref graph --label compile-connected.

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Find What Depends on a Context

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Run mix xref graph --sink MyApp.Accounts --label compile.

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Find What a Module Calls

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Run mix xref callers MyApp.Accounts.get_user!/1.

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Check for Circular Dependencies

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Run mix xref graph --format cycles --label compile.

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Red Flags to Detect

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IssueDetection CommandFix
Repo in web layergrep -r \"Repo\\.\" lib/my_app_web/Move to context
Schema with queriesgrep -r \"import Ecto.Query\" lib/my_app/**/schemas/Move queries to context
Cross-context schema importgrep -r \"alias MyApp.Other.Schema\" lib/my_app/ctx/Call context API
Business logic in LiveViewgrep -r \"Repo\\.\\|Ecto\\.Multi\" lib/my_app_web/live/Extract to context
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Boundary Verification Process

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  1. Run mix xref graph --label compile-connected for overview
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  2. Check for context cross-contamination
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  3. Verify no direct Repo calls from web layer
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  4. Ensure schemas have no side effects
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  5. Validate explicit cross-context dependencies
    6. \n
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Next Steps

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Always end with actionable follow-up — findings without a plan\nget lost:

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- `/phx:plan` — Create a plan to fix violations (recommended for 3+ issues)\n- `/phx:quick` — Fix a single boundary violation directly\n- `/phx:review` — Review specific modules for deeper issues\n
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References

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For detailed patterns, see:

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