samalone-plugins

ef-core — Claude Code Plugin

A Claude Code plugin for .NET projects using Entity Framework Core. Provides structured access to dotnet ef commands, enforces best practices, and prevents accidental edits to auto-generated files.

Installation

Add the marketplace and install the plugin:

/plugin marketplace add AntigenPlus/claude-ef-core-plugin
/plugin install ef-core@samalone-plugins

Choose user, project, or local scope when prompted.

For development/testing (loads directly without caching):

claude --plugin-dir /path/to/claude-ef-core-plugin

Repository: github.com/AntigenPlus/claude-ef-core-plugin

Features

Slash Commands

Command	Description
/ef-core:migrate <Name>	Create a new migration (auto-detects projects, handles dummy connection strings)
/ef-core:update-database [Migration]	Apply migrations to the database
/ef-core:remove-migration	Remove the last unapplied migration
/ef-core:migration-script [from] [to]	Generate a SQL deployment script
/ef-core:migration-bundle	Create a standalone migration executable
/ef-core:scaffold <conn> <provider>	Reverse-engineer entities from a database
/ef-core:db-info	Show DbContext info, migrations, and status
/ef-core:optimize	Generate a compiled model for faster startup
/ef-core:review [MigrationName]	Review a migration for risks (data loss, missing defaults, snapshot drift)
/ef-core:status	Check for pending model changes that need a migration
/ef-core:list	List all migrations (works without a database connection)

All commands auto-detect project structure, handle --project/--startup-project flags, and support multi-DbContext projects. The migrate command also handles the connection string problem by setting a dummy connection string when needed.

Auto-Loaded Rules

When Claude detects EF Core usage in your project, it automatically follows these rules:

• Never edits *.Designer.cs or *ModelSnapshot.cs files
• Reviews generated migrations for data loss risks and snapshot drift
• Flags non-nullable columns added without defaults
• Uses proper naming conventions for migrations (one migration per feature)
• Recommends SQL scripts or bundles for production deployments
• Warns about client-side evaluation pitfalls in LINQ queries
• Warns about SQL Server-specific limitations (filtered indexes on computed columns)
• Keeps Microsoft.EntityFrameworkCore.Design as a permanent dependency
• Auto-detects project topology (model project, startup project, multiple DbContexts)
• Handles dummy connection strings for migration generation

File Protection Hook

A PreToolUse hook blocks any attempt to edit or write to:

• *.Designer.cs — migration metadata files
• *ModelSnapshot.cs — model snapshot files

These files must only be modified by dotnet ef tooling. The hook provides clear error messages explaining what to do instead.

Plugin Structure

claude-ef-core-plugin/
├── .claude-plugin/
│   ├── plugin.json              # Plugin manifest
│   └── marketplace.json         # Marketplace manifest
├── skills/
│   └── ef-core/
│       ├── SKILL.md             # Core rules and best practices
│       └── commands-reference.md # Full dotnet ef command reference
├── commands/
│   ├── migrate.md               # /ef-core:migrate
│   ├── update-database.md       # /ef-core:update-database
│   ├── remove-migration.md      # /ef-core:remove-migration
│   ├── migration-script.md      # /ef-core:migration-script
│   ├── migration-bundle.md      # /ef-core:migration-bundle
│   ├── scaffold.md              # /ef-core:scaffold
│   ├── db-info.md               # /ef-core:db-info
│   ├── optimize.md              # /ef-core:optimize
│   ├── review.md                # /ef-core:review
│   ├── status.md                # /ef-core:status
│   └── list.md                  # /ef-core:list
├── hooks/
│   ├── hooks.json               # Hook configuration
│   ├── protect-generated-files.sh   # Bash hook script
│   └── protect-generated-files.ps1  # PowerShell hook script (reference)
└── README.md

Prerequisites

• .NET SDK installed
• EF Core tools installed: dotnet tool install --global dotnet-ef
• Bash available on PATH (included with Git for Windows)

Cross-Platform Notes

The hook scripts use bash by default. On Windows, this works via Git Bash (included with Git for Windows). The protect-generated-files.ps1 PowerShell script is included as an alternative. To use it, update hooks/hooks.json:

{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "Edit|Write",
        "hooks": [
          {
            "type": "command",
            "command": "powershell -File \"${CLAUDE_PLUGIN_ROOT}/hooks/protect-generated-files.ps1\""
          }
        ]
      }
    ]
  }
}