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.

lib/opencode/artifact.rb

@@ -0,0 +1,63 @@
+# frozen_string_literal: true
+
+module Opencode
+  # A file the host wants to attach to an assistant message: filename,
+  # content bytes, MIME type, and an optional trust-metadata hash.
+  #
+  # Artifacts come from two places in the substrate:
+  #
+  #   - Opencode::Exchange.tool_artifacts  — content lives inside a tool
+  #     call's input/metadata (write tool).
+  #   - Opencode::SandboxFile#as_artifact — identity conversion of a
+  #     sandbox-resident file (the default identity path).
+  #
+  # Transforms also return Artifacts — e.g. a host-rendered HTML
+  # artifact carrying a trust-metadata stamp.
+  #
+  # An Artifact knows how to attach itself to a message, idempotently:
+  # it consults `message.artifacts` to skip if its filename is already
+  # there. The attaching verb belongs to the Artifact (the noun whose
+  # state the verb consults), not to a separate Attacher class.
+  class Artifact
+    attr_reader :filename, :content, :content_type, :metadata
+
+    def initialize(filename:, content:, content_type:, metadata: {})
+      @filename     = filename
+      @content      = content
+      @content_type = content_type
+      @metadata     = metadata
+    end
+
+    # Idempotent attach. Returns true if newly attached, false if the
+    # filename was already present on the message (so callers can count
+    # what they actually persisted vs what was already there).
+    def attach_to(message)
+      return false if already_attached_to?(message)
+
+      message.artifacts.attach(
+        io:           StringIO.new(content),
+        filename:     filename,
+        content_type: content_type,
+        metadata:     metadata
+      )
+      true
+    end
+
+    def already_attached_to?(message)
+      message.artifacts.any? { |a| a.filename.to_s == filename }
+    end
+
+    def ==(other)
+      other.is_a?(Artifact) &&
+        other.filename     == filename &&
+        other.content      == content &&
+        other.content_type == content_type &&
+        other.metadata     == metadata
+    end
+    alias_method :eql?, :==
+
+    def hash
+      [ filename, content, content_type, metadata ].hash
+    end
+  end
+end