Initial public release v0.0.1.alpha2

opencode-rails — production-grade Rails integration for OpenCode.

Rails companion to opencode-ruby. ActiveRecord-aware session lifecycle
(idempotent ensure!/recreate!/abort! with row-level locks), a Turn
orchestrator driving the Reply state machine and recovering from
session-not-found, an artifact pipeline backed by ActiveStorage,
sandbox seeding, and tool-display value objects for Turbo Stream
broadcasts. Drop into any Rails 7.1+ app that wants production-grade
OpenCode streaming without rolling boilerplate.

What this version ships:
  - Opencode::Session (AR-coupled lifecycle, row-level locks)
  - Opencode::Turn (Reply state machine, session-not-found recovery)
  - Opencode::Exchange (one turn = one request/response unit)
  - Opencode::Impostor (deterministic mock for tests)
  - Opencode::Sandbox / SandboxFile (per-session FS scratch space)
  - Opencode::Transform (host-rendered artifact pipeline)
  - Opencode::Artifact / MessageArtifacts (ActiveStorage-backed)
  - Opencode::UploadedFilesPrompt (system-prompt builder)
  - Opencode::ToolDisplay (Turbo Stream value objects)
  - Opencode::ErrorReporter (pluggable adapter — Honeybadger/Sentry/etc.)
  - examples/rails_integration.rb — canonical wiring blueprint

53 smoke tests. CI on Ruby 3.2/3.3/3.4.

Ruby >= 3.2. Runtime deps: opencode-ruby = 0.0.1.alpha2,
activerecord/activestorage/activesupport >= 7.1, < 9.0.

See CHANGELOG.md for the alpha1 -> alpha2 delta.

test/opencode/impostor_test.rb

@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+require "test_helper"
+
+# Contract smoke for Opencode::Impostor. Wraps an ActiveStorage
+# attachment that's been replaced by a Transform-rendered artifact.
+# Behavioral tests against real ActiveStorage::Attachment live in
+# the host application.
+class Opencode::ImpostorTest < Minitest::Test
+  def test_initialize_takes_attachment_keyword
+    params = Opencode::Impostor.instance_method(:initialize).parameters
+    assert_includes params, [ :keyreq, :attachment ],
+      "Impostor must require an attachment: keyword (ActiveStorage::Attachment-like)"
+  end
+
+  def test_public_api
+    assert_equal %i[filename purge!].sort,
+      Opencode::Impostor.instance_methods(false).sort
+  end
+
+  def test_filename_delegates_to_attachment
+    attachment_double = Struct.new(:filename).new("legacy.html")
+    impostor = Opencode::Impostor.new(attachment: attachment_double)
+    assert_equal "legacy.html", impostor.filename
+  end
+end