Stimulus action options emitted on event side, not after #method — silently dropped (e.g. :capture)

[stevegeek]

Summary

Vident::Stimulus::Action#to_s emits action options (modifiers like :capture, :once, :passive) on the event side of the descriptor, but Stimulus's descriptor grammar requires options at the very end, after #method. The result is a descriptor Stimulus mis-parses into a bogus event name, so the listener silently never fires and the options are dropped.

Affects vident 3.1.0.

Repro

a = Vident::Stimulus::Action.from_descriptor(
  { event: "scroll", method: :scrolled, options: [:capture], window: true },
  implied: Vident::Stimulus::Controller.new(path: "forms/date_calendar", name: "forms--date-calendar")
)
a.to_s

Actual:

scroll:capture@window->forms--date-calendar#scrolled

Expected (per Stimulus):

scroll@window->forms--date-calendar#scrolled:capture

Why it's broken

Stimulus's descriptor parser (@hotwired/stimulus) is:

const descriptorPattern = /^(?:(?:([^.]+?)\+)?(.+?)(?:\.(.+?))?(?:@(window|document))?->)?(.+?)(?:#([^:]+?))(?::(.+))?$/;

Options are capture group 7 — the trailing (?::(.+))?, i.e. everything after #method:. There is no slot for options between the event name and @window.

Parsing the actual output scroll:capture@window->forms--date-calendar#scrolled:

• eventName (group 2) = scroll:capture ← bogus event type
• target (group 4) = window
• method (group 6) = scrolled
• options (group 7) = (none)

So Stimulus does addEventListener("scroll:capture", ...) with no options — a permanently dead listener. The capture/once/passive option is silently lost.

Root cause

lib/vident/stimulus/action.rb, #to_s builds the modifiers onto the event head, before @window and before ->:

def to_s
  head =
    if event
      ev = event.to_s
      ev = "#{ev}.#{keyboard}" if keyboard
      ev = "#{ev}#{modifiers.map { |o| ":#{o}" }.join}" if modifiers.any?   # <-- options on event side
      ev = "#{ev}@window" if window
      "#{ev}->"
    else
      ""
    end
  "#{head}#{controller.name}##{method_name}"
end

The modifiers segment needs to move to the tail, after #{method_name}:

def to_s
  head =
    if event
      ev = event.to_s
      ev = "#{ev}.#{keyboard}" if keyboard
      ev = "#{ev}@window" if window
      "#{ev}->"
    else
      ""
    end
  tail = modifiers.any? ? modifiers.map { |o| ":#{o}" }.join : ""
  "#{head}#{controller.name}##{method_name}#{tail}"
end

That yields scroll@window->forms--date-calendar#scrolled:capture, which parses correctly (options = capture).

Impact

Any use of action options via the DSL is silently a no-op: action(...).modifier(:capture), :once, :passive, :!passive, :stop, :prevent, :self. Found this while trying to make a scroll@window listener capture-phase (needed because scroll doesn't bubble, so a bubble-phase window listener misses nested overflow:auto scroll containers); had to drop to a hand-rolled addEventListener(..., true) in the controller because the DSL couldn't emit a working :capture.

A regression test asserting to_s for each option position (with and without @window/keyboard filter) would lock this down.