Support creating incremental Pages in Merge requests

Our normal merge-request process looks like this: the developer pushes the changes, then CI tests them, then somebody else does the review in the code. But since humans are not ideal, it is a good practice to download the code to your IDE and then run the application to check whether it does not fail/throw errors.

Since Gitlab released Pages, I had an idea in my mind: what if the last step would be automatized? What if I would use Pages to host versioned app (frontend) with branch-only changes during merge requests?

So, I have prepared the following .gitlab-ci.yml:

image: debian:jessie

stages:
  - deploy
  - cleanup

pages:
  stage: deploy
  only:
    - merge_requests
  script:
    - >
      mkdir -p public/${CI_COMMIT_REF_NAME};
      cd public/${CI_COMMIT_REF_NAME};
      echo "hello_world" > index.html;
      echo "Created page: ${CI_PAGES_URL}/${CI_COMMIT_REF_NAME}/index.html";
  artifacts:
    paths:
      - public/${CI_COMMIT_REF_NAME}

clean_after_merge_request:
  stage: cleanup
  only:
    refs:
      - master
    variables:
      - $CI_COMMIT_TITLE =~ /.*Merge branch '.+' into '.+'.*/
  script:
     - >
       MR_ORIGINAL_BRANCH=$(echo "${CI_COMMIT_TITLE}" | sed -n "s@Merge branch '\([^']*\)'.*@\1@p");
       echo "Removing Gitlab Pages: ${CI_PAGES_URL}/${MR_ORIGINAL_BRANCH}";

Simple stuff, the mechanism creates for every merge_request new directory with branch name in the public folder, and after the merge it removes it.

Problems that I have found:

1. The CI pages mechanism does not allow to add the content incrementally. It rather just replaces the whole content instead of just create an additional folder.
2. On the cleanup stage, I can, in fact, clean the application that was created during the deploy stage. But what if the merge request is closed without merging? I would want to have any mechanism that would be prone to this issue (maybe new only keyword, for example, merge_request_closed which would be fired on merge or close/remove?)
3. It would be great to have a section like Coverage on the MR page (with related link to Page) - otherwise, the user would have to look in the console logs. For example:

pages:
  stage: deploy
  page: ${CI_PAGES_URL}/${CI_COMMIT_REF_NAME}
  only:
    - merge_requests
  script:
    - >
      mkdir -p public/${CI_COMMIT_REF_NAME};
      cd public/${CI_COMMIT_REF_NAME};
      echo "hello_world" > index.html;
      echo "Created page: ${CI_PAGES_URL}/${CI_COMMIT_REF_NAME}/index.html";
  artifacts:
    paths:
      - public/${CI_COMMIT_REF_NAME}