/phoenix-code-review

name: phoenix-code-review
description: Reviews Phoenix code for controller patterns, context boundaries, routing, and plugs. Use when reviewing Phoenix apps, checking controllers, routers, or context modules.

Phoenix Code Review

Quick Reference

| Issue Type | Reference | |------------|-----------| | Bounded contexts, Ecto integration | [references/contexts.md](references/contexts.md) | | Actions, params, error handling | [references/controllers.md](references/controllers.md) | | Pipelines, scopes, verified routes | [references/routing.md](references/routing.md) | | Custom plugs, authentication | [references/plugs.md](references/plugs.md) |

Review Checklist

Controllers

• [ ] Business logic in contexts, not controllers
• [ ] Controllers return proper HTTP status codes
• [ ] Action clauses handle all expected patterns
• [ ] Fallback controllers handle errors consistently

Contexts

• [ ] Contexts are bounded by domain, not technical layer
• [ ] Public functions have clear, domain-focused names
• [ ] Changesets validate all user input
• [ ] No Ecto queries in controllers

Routing

• [ ] Verified routes (~p sigil) used, not string paths
• [ ] Pipelines group related plugs
• [ ] Resources use only needed actions
• [ ] Scopes group related routes

Plugs

• [ ] Authentication/authorization via plugs
• [ ] Plugs are composable and single-purpose
• [ ] Halt called after sending response in plugs

JSON APIs

• [ ] Proper content negotiation
• [ ] Consistent error response format
• [ ] Pagination for list endpoints

Valid Patterns (Do NOT Flag)

• **Controller calling multiple contexts** - Valid for orchestration
• **Inline Ecto query in context** - Context owns its data access
• **Using `action_fallback`** - Centralized error handling pattern
• **Multiple pipelines per route** - Composition is intentional
• **`Plug.Conn.halt/1` without send** - May be handled by fallback

Context-Sensitive Rules

| Issue | Flag ONLY IF | |-------|--------------| | Missing changeset validation | Field accepts user input AND no validation exists | | Controller too large | More than 7 actions OR actions > 20 lines | | Missing authorization | Route is not public AND no auth plug in pipeline |

Gates (run in order; each step has a pass condition)

1. **Anchored evidence** — For every planned finding, open the source and note **file path + line number** from that read (not from memory or diff snippets alone). **Pass:** each finding cites `path:line` that you opened. 2. **“Handled elsewhere” sweep** — Before reporting “missing validation,” “missing auth,” or “wrong status,” search the router (pipelines/scopes), controller (`action_fallback`, `plug`), and relevant context for existing checks. **Pass:** you recorded whether handling exists elsewhere (yes + where, or no after search). 3. **Verification protocol** — Load and apply [review-verification-protocol](../review-verification-protocol/SKILL.md) for the issue type. **Pass:** that skill’s pre-report checks for that finding class are satisfied before you write the finding. 4. **Finding shape** — Emit each issue as `[FILE:LINE] ISSUE_TITLE` with a one-line rationale tied to the cited code. **Pass:** every line matches that pattern.

Before Submitting Findings

Do not report until **Gates** above pass. For full anti-false-positive steps, follow [review-verification-protocol](../review-verification-protocol/SKILL.md).