The PR-preview site that rossjrw/pr-preview-action deploys under /pr-preview/pr-<N>/ is built from altdoc/quarto_website.yml. Three knobs decide where its GitHub links go, and right now all three point at the main repo / main branch:

• repo-url: (hardcoded to https://github.com/UCD-SERG/rpt) — drives quarto's repo-actions: [edit, source, issue] ("Edit this page", "View source").
• repo-branch: (not set, so quarto defaults to main) — the branch portion of those URLs.
• The navbar github icon's href: ($ALTDOC_PACKAGE_URL_GITHUB, substituted by altdoc from URL in DESCRIPTION) — just goes to the repo root.

For PR previews these should instead point at the PR/branch under review, so reviewers can click through to the right place. Proposed mapping:

• repo-url: → https://github.com/<head_repo_full_name>
• repo-branch: → <head_ref> (so "Edit this page" / "View source" lands on the right file in the right branch)
• Navbar GitHub icon href: → https://github.com/<base_repo>/pull/<PR#> (the PR conversation page)

docs.yaml already has github.event.pull_request.head.repo.full_name, head.ref, and number available on PR builds. The change is a small step that rewrites those three values in altdoc/quarto_website.yml on disk before altdoc::render_docs() runs; non-PR builds leave the file untouched.

Tradeoff: this is an in-place CI rewrite, not a clean templating system — the template now has "this file is mutated in PR builds" semantics that someone reading the YAML cold won't see. A comment in quarto_website.yml next to the affected keys is enough to document it.