Module urls 

Canonical page-URL derivation shared by staging, feeds, and SEO output (spec A2/B1, plan §2 item 1.2, issue #586).

Why this module exists

staticdatagen’s RSS generator hard-fails the whole build when a page lacks a permalink: front-matter key (rss-gen: “channel.link is missing”). ssg stages content through content_stager before staticdatagen::compile ever sees it, so ssg can guarantee a permalink is always present by deriving one at staging time. This module is that single derivation code path — the plan’s goal is that canonical <link>, feed <link>, and injected permalink: all agree because they all call derive_page_url.

The URL convention

Published pages use pretty directory URLs with a trailing slash, matching the Atom feed entry convention already shipped in src/plugins/postprocess/atom.rs ({base_url}/{rel_path}/) and the stager’s own tags-stub permalink (https://example.invalid/tags/):

Relative output path	Derived URL
index.html	{base_url}/
foo/index.html	{base_url}/foo/
posts/bar/index.html	{base_url}/posts/bar/
feed.xml (non-index)	{base_url}/feed.xml

Windows path separators are normalised to /; percent-encoding is left untouched (paths are already slugified upstream).

Functions

derive_output_rel_path

Maps a content-relative markdown source path to the site-relative output path staticdatagen’s compiler will write for it.

derive_page_url

Joins a site base_url and a page’s site-relative output path into the canonical absolute URL for that page.

derive_permalink

Derives the canonical permalink for a content-relative markdown source path: derive_output_rel_path piped into derive_page_url.