File Inventory

This is the full surface you need to account for when bringing the generic User-scoped MCP into another Rails project.

Core Shared Runtime

File or area	Role	Export status
`app/middleware/mcp/base_rack_app.rb`	Rack transport, token auth, rate limiting, transport reuse	Copy as-is
`app/middleware/mcp/rack_app.rb`	User-scoped authorization and request lifecycle hooks	Copy and adapt
`app/models/mcp/token.rb`	Token digest lookup, permission checks, revocation, regeneration	Copy and adapt
`app/models/mcp/activity_log.rb`	Tool call audit trail	Copy and adapt
`app/models/mcp/user_context.rb`	Thread-safe user context value object	Copy as-is
`app/models/mcp/base_tool.rb`	Base class for all tools; exposes `user` and `token`; prepends `CallLogging`	Copy as-is
`app/models/mcp/server_builder.rb`	Discovers tool namespaces and filters by permission	Copy and adapt

Tool Concerns

File or area	Role	Export status
`app/models/mcp/tools/concerns/formattable.rb`	`text_response`, `json_response`, `not_found_response` helpers	Copy as-is
`app/models/mcp/tools/concerns/listable.rb`	Pagination + plain-text list rendering	Copy as-is
`app/models/mcp/tools/concerns/tool_metadata.rb`	`mcp_domain` / `mcp_action` DSL driving permission filtering	Copy as-is

Tool Classes — The `Item` CRUD Set

File or area	Role	Export status
`app/models/mcp/tools/items/list.rb`	`list_items` — paginated, user-scoped list	Rebuild per resource
`app/models/mcp/tools/items/get.rb`	`get_item` — single record lookup	Rebuild per resource
`app/models/mcp/tools/items/create.rb`	`create_item` — safe create with validation feedback	Rebuild per resource
`app/models/mcp/tools/items/update.rb`	`update_item` — partial update, scoped find	Rebuild per resource
`app/models/mcp/tools/items/delete.rb`	`delete_item` — scoped destroy with confirmation response	Rebuild per resource

Replace Item with your real resource name. Keep the five-file layout: one tool per action, one action per class.

Token Management Surface

File or area	Role	Export status
`app/controllers/mcp/base_controller.rb`	Ensures the user is authenticated and applies the app layout	Copy and adapt
`app/controllers/mcp/tokens_controller.rb`	Token create, update, revoke, regenerate for the current user	Copy and adapt
`app/controllers/mcp/settings_controller.rb`	MCP settings landing page (optional)	Optional
`app/controllers/mcp/activity_controller.rb`	Activity log viewer (optional)	Optional
`app/policies/mcp/token_policy.rb`	Pundit policy limiting scope to `current_user`'s tokens	Adapt
`app/views/mcp/tokens/**`	Token form, permission toggles, list view	Copy and adapt

Routes And Dependency Hooks

File or area	Role	Export status
`config/routes.rb`	Mounts `/mcp` and nested token management routes	Copy and adapt
`Gemfile`	Adds `gem "mcp", "~> 0.10.0"`	Required
`app/models/current.rb`	Holds `Current.user` so downstream code sees the acting user during MCP dispatch	Recommended

Database Contract

For a fresh export, build around the final model contract rather than replaying migration history.

Recommended columns for `mcp_tokens`

user_id, non-null, foreign key
name, non-null
token_digest, non-null, unique
token_prefix, nullable (UI only)
permissions, JSON, non-null, default {}
scope, non-null, default "user"
last_used_at
revoked_at
timestamps

Recommended indexes for `mcp_tokens`

unique on token_digest
user_id
composite [user_id, revoked_at] for active-token lookups

Recommended columns for `mcp_activity_logs`

mcp_token_id, non-null, foreign key
user_id, non-null, foreign key (denormalized for fast per-user queries)
tool_name, non-null
domain, non-null
action_type, non-null
arguments, JSON
result_summary, JSON
status_code, integer
timestamps

Recommended indexes for `mcp_activity_logs`

mcp_token_id
composite [mcp_token_id, created_at]
user_id
composite [user_id, created_at]

Tool Inventory Snapshot (Generic Package)

The generic package ships one domain with five tools:

items — list_items, get_item, create_item, update_item, delete_item

Each tool declares:

tool_name "<verb>_item"
mcp_domain "items"
mcp_action "read" | "create" | "update" | "delete"
description — one sentence naming the resource and the action
input_schema — tight, explicit property definitions

Must-Copy Minimum Set

If you want a minimal but working export, start with these:

Gemfile dependency on mcp
app/middleware/mcp/base_rack_app.rb
app/middleware/mcp/rack_app.rb
app/models/mcp/token.rb + migration
app/models/mcp/activity_log.rb + migration
app/models/mcp/user_context.rb
app/models/mcp/base_tool.rb
app/models/mcp/server_builder.rb
app/models/mcp/tools/concerns/*
One tool class to prove the wiring (Mcp::Tools::Items::List is a good first target)
Route: mount Mcp::RackApp.new, at: "/mcp"

Everything else — token UI, activity viewer, additional tool domains — can be layered in after the endpoint already serves tools/list.