Phlex support

Phlex support comes from the gem hibiki_phlex: reactive components. A Phlex component is a plain Ruby object, so Hibiki::Reactive gives it per-instance signals read as ordinary method calls — no .value anywhere in view_template — and a render effect re-renders it whenever one of those signals changes.

signal write → render effect re-runs → component re-renders
(same instance) → fresh HTML handed to your block

Transport-agnostic on purpose: the gem depends only on hibiki and phlex. The block receiving the HTML decides where it goes — broadcast it over Turbo Streams, transmit it down a channel subscription, write it to a file, diff it in a test.

Requires Phlex >= 2.4, < 2.5 (see the version-pin rationale below) and Ruby >= 3.4:

# Gemfile
gem "hibiki_phlex"

Usage

class TodoList < Phlex::HTML
  include Hibiki::Reactive
  include Hibiki::Phlex::Rerenderable

  state(:items) { [] }
  derived(:remaining) { items.count { |item| !item[:done] } }

  def view_template
    div(id: "todos") do
      h2 { "Todos — #{remaining} remaining" }
      ul { items.each { |item| li { item[:title] } } }
    end
  end

  # Signals compare with ==; build new values instead of mutating in place.
  def add(title) = self.items = items + [{ title:, done: false }]
end

list = TodoList.new

effect = Hibiki::Phlex.render_effect(list) do |html|
  # your transport — e.g. inside a Hibiki::Rails::Channel:
  # broadcast_replace target: "todos", html:
end

list.add("write docs")   # → the block runs again with fresh HTML
effect.dispose           # or let an enclosing Hibiki.root own teardown

• The effect’s first run is the dependency-collecting initial render: signals read inside view_template subscribe it through plain method calls, and that first HTML is yielded too.
• Re-renders happen on the same instance — signal identity lives in the instance, so a fresh instance per render would reset every signal. That’s what Rerenderable exists for.
• render_effect(component, scheduler:) passes the scheduler through to Hibiki::Effect, so reruns can be deferred or debounced (e.g. Hibiki::Rails::Debounce).
• Returns the Hibiki::Effect. Created inside Hibiki.root (or another effect), the owner tree disposes it automatically; a bare caller calls #dispose.

With hibiki_rails

The combination is the LiveView-ish loop — one signal graph per cable connection, one render effect per component:

class TodosChannel < ApplicationCable::Channel
  include Hibiki::Rails::Channel

  def build_graph
    @list = TodoList.new
    Hibiki::Phlex.render_effect(@list) do |html|
      broadcast_replace target: "todos", html:
    end
  end

  def add(data) = @list.add(data["title"])
end

Granularity is inherent and worth knowing: the ERB style in hibiki_rails is one effect per partial (fine-grained), a Phlex render effect is one effect per component (component-grained). Both are correct; pick per page. The initial-state pattern (server-rendered placeholder + subscribe after the Turbo stream confirms) is transport-side — see Rails usage. On the transmit transport there is no such ordering problem (see The JS client).

Why the strict Phlex pin

Phlex components are one-shot: an instance renders once, and a second call raises Phlex::DoubleRenderError. Phlex 2 tracks “spent” purely through the private @_state ivar — everything else about a render is per-call — so Rerenderable#rerender clears it and calls again. That is the entire adapter, but it leans on a private implementation detail, so:

• the gemspec allows only verified Phlex minors (>= 2.4, < 2.5), and
• a contract spec pins the upstream behavior itself, so bumping the bound fails loudly in CI if the internals moved.