Related content - give sort precedence to same .Type and/or .Section

feature
1

Configuration

[taxonomies]
tag = 'tags'

[[related.indices]]
name = 'tags'
weight = 100

Content structure

content/
├── books/
│   ├── book-1.md   <-- tags = a, b, c
│   ├── book-2.md   <-- tags = a, b, c
│   ├── book-3.md   <-- tags = a, b
│   └── book-4.md   <-- tags = a
└── films/
    ├── film-1.md   <-- tags = a
    ├── film-2.md   <-- tags = a, b
    └── film-3.md   <-- tags = a, b, c

Code

{{ with site.RegularPages.Related . }}

Current outcome when viewing book-1, in this sort order

Film 3   tags = a, b, c
Book 2   tags = a, b, c
Film 2   tags = a, b
Book 3   tags = a, b
Film 1   tags = a
Book 4   tags = a

N.B. All pages have different dates, and the date affects the sort order among items with matching tags.

I tried to give the date zero weight, in case that might override the default behavior:

[[related.indices]]
name = 'date'
weight = 0

Desired outcome when viewing book-1, in this sort order, regardless of date

Book 2   tags = a, b, c
Film 3   tags = a, b, c
Book 3   tags = a, b
Film 2   tags = a, b
Book 4   tags = a
Film 1   tags = a

Approach

I think this could be accomplished by adding .Type and/or .Section to the available indices.

Example

git clone --single-branch -b hugo-forum-topic-42762 https://github.com/jmooring/hugo-testing hugo-forum-topic-42762
cd hugo-forum-topic-42762
hugo server
2

I found a way to do this… cascade type down from site configuration.

config.toml 
[taxonomies]
tag = 'tags'

[[cascade]]
type = 'books'
[cascade._target]
path = '/books/**'

[[cascade]]
type = 'films'
[cascade._target]
path = '/films/**'

[related]
includeNewer = true
threshold = 80
toLower = true

[[related.indices]]
name = 'tags'
weight = 60

[[related.indices]]
name = 'type'
weight = 30

But it would be convenient if the page .Type were available as an index, instead of having to cascade the value down to .Params.type.