runLoop function

  async function runLoop(signal: AbortSignal): Promise<void> {
    if (!flow || !rng) return;

    // Navigate to baseUrl before executing steps
    if (flow.metadata.baseUrl) {
      log.info(`Navigating to baseUrl: ${flow.metadata.baseUrl}`);
      const loaded = await navigateAndWait(tabId, flow.metadata.baseUrl);
      if (!loaded) {
        log.warn(`Failed to navigate to baseUrl: ${flow.metadata.baseUrl}`);
      }
      await injectContentScript(tabId);
    }

    for (; stepIndex < flow.steps.length; stepIndex++) {
      if (signal.aborted) return;
      await waitIfPaused();
      if (signal.aborted) return;

      const step = flow.steps[stepIndex]!;
      emitProgress(step);

      // Apply delay before step
      const delay =
        config.useRecordedTimings && step.delayBefore
          ? step.delayBefore
          : config.stepDelay;

      if (delay > 0 && stepIndex > 0) {
        try {
          await sleep(delay, signal);
        } catch {
          return; // aborted during delay
        }
      }

      // Resolve value for fill steps
      let resolvedValue: string | undefined;
      if (step.action === "fill" && step.valueSource) {
        resolvedValue = resolveValueSource(step.valueSource, generate);
      }

      // Execute
      let result: StepResult;
      if (step.action === "navigate") {
        result = await executeNavigateStep(step);
      } else {
        // Before interaction, move cursor (sent as separate message)
        if (
          step.selector &&
          config.highlightDuration > 0 &&
          config.showCursor !== false
        ) {
          try {
            await chrome.tabs.sendMessage(tabId, {
              type: "DEMO_CURSOR_MOVE",
              payload: { selector: step.selector, durationMs: 400 },
            });
            await sleep(config.highlightDuration, signal);
          } catch {
            // cursor overlay is optional — ignore
          }
        }

        // Click effect
        if (step.action === "click" && config.showCursor !== false) {
          try {
            await chrome.tabs.sendMessage(tabId, {
              type: "DEMO_CURSOR_CLICK",
            });
          } catch {
            // ignore
          }
        }

        // Highlight element
        if (config.highlightDuration > 0) {
          try {
            await chrome.tabs.sendMessage(tabId, {
              type: "DEMO_HIGHLIGHT_ELEMENT",
              payload: { step, durationMs: config.highlightDuration },
            });
          } catch {
            // ignore
          }
        }

        result = await sendStepToContentScript(step, resolvedValue);
      }

      stepResults.push({ stepId: step.id, result });

      // Handle failure
      if (result.status === "failed") {
        if (step.optional) {
          log.info(
            `Optional step ${step.id} failed, continuing:`,
            result.error,
          );
        } else {
          log.warn(`Step ${step.id} failed:`, result.error);
          setStatus("failed");
          callbacks.onComplete?.(buildResult());
          return;
        }
      }

      // Apply delay after step
      if (step.delayAfter && step.delayAfter > 0) {
        try {
          await sleep(step.delayAfter, signal);
        } catch {
          return;
        }
      }
    }

    // All steps complete
    setStatus("completed");
    chrome.tabs
      .sendMessage(tabId, { type: "DEMO_CURSOR_DESTROY" })
      .catch(() => {});
    callbacks.onComplete?.(buildResult());
  }