Boundaries

What the source does

• FilesystemNone observedNo reads or writes in the source
• NetworkNone observedNo outbound calls in the source
• ShellNone observedNo commands run in the source
• DependenciesPinnedNothing floats
• SecretsNone foundNo keys in source

Five audit layers

Gates applied: no behavioural pass.

Audit 0.4.1 · source sha 492f17636999 · 18 Oct 2026Report an issue or request a re-scan

• Publisheroliver-kriska GitHub userOwner of the repository this skill is read from
• Source folderoliver-kriska/claude-elixir-phoenix/plugins/elixir-phoenix/skills/boundariesThe exact folder we audited
• LicenceMITAs the repository states it
• Commit pinned for this verdict492f17636999A new audit runs when the source changes
• Repository statusNot archivedLast push 2 days ago
• Sandboxed runNot runSkills are read, not executed; layer L4 is skipped

Its description: Analyze Phoenix context boundaries and module coupling via mix xref. Use when checking cross-context calls, validating dependencies, before splitting modules, or reviewing architecture.

---
name: boundaries
description: Analyze Phoenix context boundaries and module coupling via mix xref. Use when checking cross-context calls, validating dependencies, before splitting modules, or reviewing architecture.
effort: medium
argument-hint: "[--assess|--fix]"
---

# Phoenix Context Boundary Validation

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

## Usage

```
/phx:boundaries              # Check for violations
/phx:boundaries --assess     # Score context health (0-100)
/phx:boundaries --fix        # Suggest fixes for violations
```

## `--assess` Mode: Context Health Score

Evaluate overall boundary health with a quantified score.

### Metrics Calculated

| Metric | Healthy Range | Red Flag | Weight |
|--------|---------------|----------|--------|
| Modules per context | 3-15 | >20 or <2 | 20% |
| Public API surface | 5-30 funcs | >40 funcs | 15% |
| Fan-out (contexts called) | 1-4 | >6 | 20% |
| Fan-in (called by contexts) | 1-6 | >10 | 15% |
| Circular dependencies | 0 | >0 | 15% |
| Boundary violations | 0 | >0 | 15% |

### Commands for Assessment

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

### Output Format

```markdown
## Context Health Assessment

### Overall Score: 82/100 (Good)

| Context | Modules | API | Fan-Out | Fan-In | Score |
|---------|---------|-----|---------|--------|-------|
| Accounts | 5 | 12 | 2 | 4 | 95 |
| Orders | 18 | 45 | 8 | 3 | 62 |
| Shared | 2 | 8 | 0 | 12 | 78 |

### Issues Found

1. **Orders** - Too large (18 modules, 45 funcs)
   - Consider: Extract Fulfillment, Invoicing sub-contexts

2. **Orders** - High fan-out (8 contexts)
   - Consider: Review if all dependencies necessary

### Recommendations

- Split Orders into Orders + Fulfillment
- Review Accounts ← Billing dependency
```

## Iron Laws - Never Violate These

1. **Controllers call only contexts** - No direct Repo access from web layer
2. **Schemas are pure data** - No side effects, no Repo calls in schema modules
3. **Contexts own their schemas** - Don't import schemas from other contexts
4. **Explicit dependencies only** - Cross-context calls must be intentional
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

## Dependency Rules

| Layer | Can Call | Cannot Call |
|-------|----------|-------------|
| Controllers | Contexts, Plug, Conn | Repo, Schemas directly |
| LiveViews | Contexts, Components, PubSub | Repo, Schemas directly |
| Contexts | Own schemas, Repo, other contexts | Web layer modules |
| Schemas | Ecto types, validations | Contexts, Repo |

## Analysis Commands

### Check Compile Dependencies

Run `mix xref graph --label compile-connected`.

### Find What Depends on a Context

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

### Find What a Module Calls

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

### Check for Circular Dependencies

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

## Red Flags to Detect

| Issue | Detection Command | Fix |
|-------|------------------|-----|
| Repo in web layer | `grep -r "Repo\." lib/my_app_web/` | Move to context |
| Schema with queries | `grep -r "import Ecto.Query" lib/my_app/**/schemas/` | Move queries to context |
| Cross-context schema import | `grep -r "alias MyApp.Other.Schema" lib/my_app/ctx/` | Call context API |
| Business logic in LiveView | `grep -r "Repo\.\|Ecto\.Multi" lib/my_app_web/live/` | Extract to context |

## Boundary Verification Process

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

## Next Steps

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

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

## References

For detailed patterns, see:

- `${CLAUDE_SKILL_DIR}/references/context-design.md` - Context design principles
- `${CLAUDE_SKILL_DIR}/references/refactoring-boundaries.md` - Fixing boundary violations

Excerpt, first 4,619 characters of SKILL.md, verbatim from the audited commit. It is text from someone else’s repository, quoted so you can judge it before your agent reads it.

git clone https://github.com/oliver-kriska/claude-elixir-phoenix
git -C claude-elixir-phoenix checkout 492f17636999

Works in

1. 2026-10-18
   ✓SAFE B 89 / 100

   first audit · source 492f17636999

Questions about Boundaries

• github.com/oliver-kriska/claude-elixir-phoenix/tree/main/plugins — the audited source at commit 492f17636999 and every finding aboveObserved · 18 Oct 2026

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