function createInstallBaseAction({ messageTypes, requestConsumerTokenServiceOnce, sendRuntimeMessage,
  appendBackgroundRequestLog, openInstallBaseModal, environment }) {
  const { document } = environment;
  const pending = new Map();

  async function load(partyNumber) {
    const authorizations = await requestConsumerTokenServiceOnce();
    const response = await sendRuntimeMessage({
      type: messageTypes.requestInstallBase, partyNumber,
      authorizations: { accountSummary: authorizations.accountSummary, installBase: authorizations.installBase }
    });
    appendBackgroundRequestLog(response?.debugRequests);
    if (!response?.ok) throw new Error(response?.error || "Unable to load installed base.");
    return response.items;
  }

  function createInstallBaseButton(opportunity) {
    const button = document.createElement("button");
    button.type = "button";
    button.className = "opportunities-extension-action-button";
    button.title = "View customer installed base";
    button.setAttribute("aria-label", `View installed base for ${opportunity.CustomerAccount?.PartyUniqueName || "customer"}`);
    const icon = document.createElementNS("http://www.w3.org/2000/svg", "svg");
    icon.setAttribute("viewBox", "0 0 24 24");
    icon.setAttribute("aria-hidden", "true");
    icon.setAttribute("focusable", "false");
    const path = document.createElementNS("http://www.w3.org/2000/svg", "path");
    path.setAttribute("d", "M4 3h16v7H4z M4 14h16v7H4z M7 6.5h.01 M7 17.5h.01 M11 6.5h6 M11 17.5h6 M8 10v4 M16 10v4");
    path.setAttribute("fill", "none");
    path.setAttribute("stroke", "currentColor");
    path.setAttribute("stroke-width", "1.7");
    path.setAttribute("stroke-linecap", "round");
    path.setAttribute("stroke-linejoin", "round");
    icon.append(path);
    button.append(icon);
    button.addEventListener("click", async () => {
      const view = openInstallBaseModal(opportunity, button);
      const partyNumber = String(opportunity.CustomerAccount?.PartyNumber || "");
      try {
        if (!partyNumber) throw new Error("Customer Party Number is unavailable.");
        if (!pending.has(partyNumber)) {
          const request = load(partyNumber).finally(() => { if (pending.get(partyNumber) === request) pending.delete(partyNumber); });
          pending.set(partyNumber, request);
        }
        view.render(await pending.get(partyNumber));
      } catch (error) {
        view.render([], error.message || "Unable to load installed base.");
      }
    });
    return button;
  }
  return { createInstallBaseButton, resetRequests: () => pending.clear() };
}