The navigation rail orders by file kind before course order — a page with children can never precede one without #3406

Why MeshWeaver core — checked, not assumed

The rail is built and rendered here and nowhere else: src/MeshWeaver.Graph/SuppliedNavigationRail.cs (Plan, Render), whose only caller is src/MeshWeaver.Graph/MarkdownOverviewLayoutArea.cs. Verified by grepping SuppliedNavigationRail across MeshWeaver, MeshWeaver.Plugins and MeshWeaver.Education — it appears only under MeshWeaver/src/. The two alternatives were ruled out: Plugins owns the supplier (Edu's EduCourseNavigationProvider implements core's INodeNavigationProvider) but the split happens after the supplier hands over its already-ordered entries, and the only satellite-side workaround — stop declaring children — would cost the collapsible lessons; Education authors the Order values and owns neither side of the rendering. gh search issues --owner Systemorph on SuppliedNavigationRail / "navigation rail order" returns no prior report. Per the fleet's conserve-work-products rule the durable home is a page under src/MeshWeaver.Documentation/Data/Architecture/; this issue is the pointer.

How to reproduce

1. On any mesh with the Edu package, open a course whose lessons have children — https://memex.localhost:8443/AgenticOffice will do; every course qualifies, since a lesson carries Exercise, Solution, Quiz.
2. Read the left rail top to bottom and compare with the Order values in the course's front matter (AgenticOffice/*.md, */index.md, *.json).
3. Observed: every childless page first, in order; then every page with children, in order. Lessons 1–4 render after the coach, the assistant and the exercises.
4. Unit-level: build a NodeNavigation whose first entry has children and whose second does not, call SuppliedNavigationRail.Plan then Render, and read the emitted sequence — the second entry precedes the first.

What happens

Plan partitions the supplied entries into Pages (no children) and Groups (children), and Render emits Home → every Page → every Group. The supplied order — Order then Name, from CourseShellAreas.SelectCoursePages — survives within each bucket and is lost between them.

Measured

memex.localhost, AgenticOffice, 2026-09-06. One rail, two correctly-ordered blocks:

README 0 · Übungen 55 · Coach 70 · Assistent 75 · Treuhänderin 78 · Deine Übungen 80 · Erklärvideo 90
Lektion 1 (1) · Lektion 2 (2) · Lektion 3 (3) · Lektion 4 (4) · Musterfirma 50 · Die Agenten 85

The four lessons carry orders 1–4 and render tenth to thirteenth, because they have Exercise, Solution, Quiz and Dokumente beneath them. No Order value can fix this — the numbers are already right.

Why it matters

A course author's only lever over the rail is Order, and it silently cannot express a reading order that mixes leaf pages with lesson folders — which is every course. MeshWeaver.Education has the intended sequence ready for all nine courses (its issue links here); none of it can render until this does.

Suggested fix

Rail carries one ordered sequence of items — link or group — instead of Pages and Groups, and Render walks it once. Keep Plan pure so its tests keep pinning the contents, and keep the three properties the class documents as deliberate: the title is a link and never the collapsible root; an entry with children is a group and its own first link; the current entry stays in the tree as an active link.

🤖 Generated with Claude Code

https://claude.ai/code/session_01HKEkt3bwipBcsvuGXQWV7F