blockscout

Create, adjust, or inspect OpenAPI declarations for Blockscout API v2 endpoints. Use this skill whenever the user asks to: add an OpenAPI spec to an endpoint that lacks one, update a spec after controller/view changes, audit or fix an existing OpenAPI declaration, or work with open_api_spex annotations in the Blockscout codebase. Also trigger when the user mentions 'swagger', 'openapi', 'open_api_spex', 'API spec', 'API schema', or 'operation macro', or when debugging failures like 'response schema mismatch', 'CastAndValidate rejection', 'json_response validation error', 'Unexpected field', or extra/missing keys in API responses.

Use when refactoring Elixir multi-clause functions, extracting helper functions, or fixing Credo readability warnings caused by placing `defp` helpers between clauses of the same function. Keeps function clauses contiguous and moves helpers below the full clause group.

Ensure every newly introduced environment variable is also added to docker-compose/envs/common-blockscout.env so local Docker setups stay aligned with runtime configuration.

Replace `with` expressions that contain only a single `<-` clause and an `else` branch with a `case` expression. This addresses the Credo warning "with contains only one <- clause and an else branch, consider using case instead" and produces cleaner, more idiomatic Elixir code.

Use when working on Elixir code with Credo predicate naming warnings, boolean helper functions, or renaming functions that start with is_. Prevents violations like: Predicate function names should not start with 'is' and should end in a question mark.

Define module aliases at the top of the file instead of using fully qualified nested module names in function bodies. Improves code readability and maintainability while addressing Credo style warnings.

Ensure that aliases are alphabetically ordered within their groups to maintain consistent code style and address Credo readability warnings.

Fixes code formatting in the Blockscout Elixir project using mix format. Use when you need to fix formatting violations, code style inconsistencies, or ensure consistent code formatting. For linting issues, use `mix credo`. Use this skill for every change made.

Optimize list checks by comparing against empty lists instead of using length/1. Avoid expensive list traversal operations when checking if a list is empty or has elements. Use pattern matching or empty list comparison for better performance.

Compile the Blockscout Elixir project to verify all dependencies and code changes work correctly. Use this skill before finalizing changes to ensure the project builds successfully without errors.

Generates Ecto migrations for the Blockscout Elixir project using mix ecto.gen.migration command. Use when you need to create database schema changes, add tables, modify columns, or manage database structure.

Build lists efficiently using prepend operations and Enum.reverse/1 instead of append. Appending to lists is O(n) while prepending is O(1). Use [head | tail] notation and reverse at the end when order matters.

Generate background migration modules for creating, dropping, or renaming database indexes on large tables using the Explorer.Migrator.HeavyDbIndexOperation framework. Automatically updates the BackgroundMigrations cache module with proper tracking. These migrations run in the background with progress tracking and dependency management. Use this skill for requests on creating background migrations to delete / create / rename indexes on large tables (logs, internal_transactions, token_transfers, addresses, transactions, blocks, etc.) to avoid blocking the database.