[ownedbycats]

Modified from 'Prompt for Confirmation' (thanks to capink for assistance) is "Prompt for Action,' to enable selected actions using a yes/no prompt.

from qt.core import QWidget, QVBoxLayout, QGroupBox, QTextEdit

from calibre.gui2 import question_dialog
from calibre_plugins.action_chains.actions.base import ChainAction

class ConfirmConfigWidget(QWidget):
    def __init__(self, plugin_action):
        QWidget.__init__(self)
        self._init_controls()

    def _init_controls(self):

        l = QVBoxLayout()
        self.setLayout(l)

        gb = QGroupBox('Confirm message')
        gb_l = QVBoxLayout()
        gb.setLayout(gb_l)

        self.tb = QTextEdit()
        self.tb.insertPlainText('Do you want to run the next action?')

        gb_l.addWidget(self.tb)
        l.addWidget(gb)

    def load_settings(self, settings):
        if settings:
            self.tb.setText(settings['message'])

    def save_settings(self):
        settings = {}
        settings['message'] = self.tb.toPlainText()
        return settings

class ConfirmAction(ChainAction):

    name = 'Prompt for Action'

    def config_widget(self):
        return ConfirmConfigWidget

    def run(self, gui, settings, chain):
        message = settings.get('message', 'Do you want to run the next action?')
        if question_dialog(gui, _('Are you sure?'), message, show_copy_button=False):
            chain.set_chain_vars({'prompt_action': 'Yes'})

Place the module action somewhere in the chain, obviously before the action you wish to prompt for, and then add the

program: globals(prompt_action)
text = Yes

condition to the actions you wish to prompt for.

I've attached a sample chain for demonstration.