Processing Architecture

The stock mdBook pipeline is extended with two registrations of the same executable:

SUMMARY.md
    |
    v
mdBook loads listed UTF-8 files as Chapter.content
    |
    v
mdBook's index preprocessor
    |
    v
mdbook-structured render
    |  parse eligible sources, project, assign routes, render semantic HTML
    v
mdBook's links preprocessor
    |  expand the normal Markdown helpers/includes
    v
mdbook-structured rewrite-links
    |  resolve Markdown links to registered chapter outputs
    v
stock mdBook HTML renderer

The phases are separate because mdBook’s built-in links preprocessor scans chapter text for helper syntax. render runs after index, so it sees the final logical chapter arrangement while the original source_path is still available. It replaces eligible chapter content before helper expansion, so encoded generated values and source text cannot be mistaken for mdBook helper directives. rewrite-links runs after links, so ordinary Markdown links introduced by includes are covered too.

The pipeline delegates through focused contracts:

• the structured core parses source text and exposes the parser-neutral document model;
• route projection assigns deterministic structured chapter paths and rejects duplicate final chapter routes before mutation;
• chapter-link rewriting resolves or diagnoses authored destinations against the projected chapter map; and
• HTML presentation defines the raw-HTML framing, semantic markup, styling hooks, and progressive behavior.

The executable is intentionally thin. It loads configuration, invokes the core library, projects errors into protocol-friendly diagnostics, and writes the resulting book. The same core library may later be used by an in-process build driver without changing its interface, but an in-process integration is not a v1 requirement.

The exact subprocess protocol, phase registration, renderer support, and installer commands belong to Configuration and operations.