rigor-activestorage

Walks ActiveRecord model files for has_one_attached / has_many_attached macros and types the attachment accessors they generate, so navigating an attachment resolves through ActiveStorage’s own RBS surface instead of falling to the untyped envelope. It reads source only — no Rails runtime dependency.

It ships bundled in rigortype. Activate it under plugins::

plugins:
  - rigor-activestorage

What it infers

class User < ApplicationRecord
  has_one_attached :avatar
  has_many_attached :photos
end

user = User.find(1)
user.avatar           # Nominal[ActiveStorage::Attached::One]
user.avatar.attached? # resolves through ActiveStorage's RBS
user.photos           # Nominal[ActiveStorage::Attached::Many]

Macro	Accessor	Contributed type
has_one_attached :avatar	user.avatar	Nominal[ActiveStorage::Attached::One]
has_many_attached :photos	user.photos	Nominal[ActiveStorage::Attached::Many]

Setters (user.avatar = …) and attachment-name calls with arguments decline — those are covered by ActiveStorage’s own RBS.

Diagnostics

Rule	Severity	When
plugin.activestorage.attachment-call	info	a recognised model.attachment_name call surfaces; confirms the model → attachment mapping
plugin.activestorage.load-error	warning	discovery failed (e.g. the model directory is inaccessible under the IoBoundary trust policy)

No :error diagnostics in this slice — the value is the return-type contribution; an “unknown attachment name” rule is a future slice.

Configuration

plugins:
  - gem: rigor-activestorage
    config:
      model_search_paths: ["app/models"]   # default

With or without rigor-activerecord

The plugin discovers model files independently, so it works stand-alone. When rigor-activerecord is also active the two coexist (each contributes its own per-call return type and the contribution merger reconciles); the :model_index dependency is declared optional, reserved for a future slice that would restrict attachment recognition to discovered AR classes.

Plugin internals

The discovery pass, the AttachmentIndex, and the contract surfaces this plugin exercises are in the plugin’s README. To write a plugin, see examples/ and the rigor-plugin-author skill.