`sidebar: auto` does not update with document changes

[Enteleform]

• [x] I confirm that this is an issue rather than a question.

Bug report

Steps to reproduce

1. create a new VuePress project
2. create ./docs/README.md
   • use setting sidebar: auto
   • add some headings & text
3. run vuepress dev docs --host localhost
4. delete some of the headings & text

What is expected?

1. the main document text will update to reflect the changes
2. the sidebar will update to reflect the new hierarchy of the document

What is actually happening?

1. ✔️ the main document text reflects the changes
2. ❌ the sidebar persists the hierarchy of the document that existed previous to the changes

Other relevant information

• possibly related to #1399

• output of npx vuepress info in my VuePress project:

  System:
  OS: Windows 10 10.0.18362
  CPU: (8) x64 Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz
  Binaries:
  Node: 12.6.0 - C:\_\Dev\NodeJS\12\node.EXE
  Yarn: 1.16.0 - C:\_\Dev\Yarn\bin\yarn.CMD
  npm: 6.9.0 - C:\_\Dev\NodeJS\12\npm.CMD
  Browsers:
  Edge: 44.18362.449.0
  npmPackages:
  @vuepress/core: Not Found
  @vuepress/theme-default: Not Found
  vuepress: ^1.3.1 => 1.4.0
  npmGlobalPackages:
  vuepress: Not Found

[Enteleform]

Update:

I just noticed that changes made to themeConfig.sidebar are not reflected either.

[Mister-Hope]

Yes that is ture. The sidebar is rendered based on the $page or , the same object $site.pages.

This variable is generated when build starts, and will not change when hotload triggers.

So anything related to it won't support hotload, such as sidebar, frontmatter, prev and next links, last edit time and so on.

It's not a bug I think, just a feature enhancement.

[Mister-Hope]

@meteorlxy @kefranabg I have seen feture request like this a few times, why not make $site.pages support hot load?

I am willing to help, but I would like to ask first, as a few PR of me is not being reviewed so far.

To avoid wasting your time, it's best to open a feature request issue first and wait for approval before working on it.

[haoranpb]

I think it is a bug, see #1283 . They simply don't have the time to dig deep into it.

[Mister-Hope]

I followed this issue, but uliuz adds few comment in his code, so there are about 1/3 source code of @vuepress/core I can not understand it's meaning. A lot of functions have short names, and with plenty of variables, hard for me to figure out what is it doing. So ..... 😅 I think I cannot help with this one.

[sdwru]

I think it is a bug, see #1283 . They simply don't have the time to dig deep into it.

Then they don't have the time to create a working product because this is essential to a working product imo.