ConTeXt: Override global project value within a product

Question

Background

Looking to understand the definitive relationship between projects, products, environments, and components.

Minimum Working Example

Here's the directory structure showing the problem:

project
├── project/novel
│   ├── project/novel/component.tex
│   ├── project/novel/contents.tex
│   ├── project/novel/prd_para.tex
│   └── project/novel/product.tex
├── project/prj_para.tex
└── project/project.tex

./project/project.tex

\startproject project
  \environment prj_para

  \product product
\stopproject

./project/prj_para.tex

\startenvironment prj_para
  \define\bookname{Project Name}
\stopenvironment

./project/novel/prd_para.tex

% Does not override \bookname from prj_para.tex?
\startenvironment prd_para
  \define\bookname{Product Name}
\stopenvironment

./project/novel/component.tex

\startcomponent component
  \project project

  \bookname

  \input contents
\stopcomponent

./project/novel/contents.tex

Pride and Prejudice

Jane Austen

\section[title={chapter-1},reference={chapter-1}]

It is a truth universally acknowledged, that a single man in possession of a good fortune, must be in want of a wife.

./project/novel/product.tex

\startproduct
  \project project

  \environment prd_para

  \component component
\stopproduct

Building

The project is built from within the project directory:

context novel/product --path=novel 

Setup

The following setup is what I'd like to achieve:

Every product "inherits" its environment settings from a global project. Each product can override specific settings. For example, the project could define Arial as the base font for all products, but one product could redefine it as Helvetica.

Problem

Ideally, the setups in the project-level prj_para.tex (i.e., "project-wide" as per the project structure diagram) could be changed in the product-level prd_para.tex.

However, the value for \bookname is always Project Name, rather than Product Name. Here is how the output appears:

Question

Using environments, projects, products, and components, how can setups in the project-wide environments be changed by the product-specific environments?

In short, how can "Product Name" be output instead?

References

Various documentation sources seem to contradict each other, for example startcomponent shows:

\startcomponent *
   \project projectname

While Project structure shows:

\startcomponent c_editorial
  \product prd_year2004-01 % but you can use it in other products anyway

Neither Magazine #1101, July 2011 nor Magazine #1101, September 2016 explicitly state how \startcomponent/\stopcomponent is codified in relation to either projects or products.

The mailing list has numerous questions with specific answers, but nothing broad in scope. A Python Script generates files and directories, but without understanding how those files and directories relate, it offers little insight.

The wiki states:

• a project links one or more products to their environment
• a product contains several components
• an environment defines the common layout (etc.) of a project

In addition, there are numerous answers on TeX.SE, but few show a tree with all files and directories:

• https://tex.stackexchange.com/a/490603/2148
• https://tex.stackexchange.com/a/377506/2148
• ConTeXt project structure: Component not linking to environment via product
• https://tex.stackexchange.com/a/192552/2148

Answer 1

The following works as expected using the given directory hierarchy:

% File: prj_para.tex
\startenvironment *
  \setuplayout[
    grid=yes,
  ]

  \define\bookname{Project Name}
\stopenvironment

% File: prd_para.tex
\startenvironment *
  \setuplayout[
    grid=no,
  ]

  \define\bookname{Product Name}
\stopenvironment

% File: component.tex
\startcomponent *
  \project project

  \bookname

  \component contents
\stopcomponent

% File: product.tex (note that * was missing)
\startproduct *
  \project project

  \environment prd_para

  \component component
\stopproduct

This produces:

If we remove the \setuplayout from prd_para.tex, the output changes to grid-aligned typesetting: