A chapter with an order of its own

A chapter orders its own notes now, chosen in the same dialog as its name,
mark and colour -- one decision about one thing. The notebook's setting
governs the notebook's own list; a chapter is a place someone made and
filled, so a reference chapter can stay alphabetical while the notebook
around it stays as it was arranged. It starts hand-made, and a chapter put
in one of the other orders loses its lines and its handles exactly as the
notebook does: neither means anything against an order the app is choosing.

A line still would not go under another line, and the comparator was only
half of it. The write was then thrown away by the "did anything change?"
test, which sorted the separators before comparing them -- to ignore the
other chapters' lines riding along in the same field -- and a sorted
comparison cannot see a sequence. Two lines in one gap carry the same
position, so swapping them changes nothing else. It compares this list's own
lines, in order.

An open chapter swelled while rearranging: the strips at the two ends of its
list stood open for the whole of the mode, adding half a finger of empty
space inside every chapter. They are thin now, and only there while
something is actually being carried -- which is also why the suite presses
first and aims afterwards.

Server: sort_mode on chapters, validated against the same five modes as a
notebook's, and set outside the COALESCE so null means the hand-made order
rather than "leave it alone".

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

CHANGELOG.md

@@ -8,6 +8,35 @@ not from the output of `docker push`.
 
 ---
 
+## 2026-08-17 — A chapter with an order of its own
+
+**Images** — web `sha256:PENDING`, server `sha256:PENDING`
+
+The server image changed: `sort_mode` on chapters.
+
+**Added**
+- **A chapter orders its own notes**, chosen in the same dialog as its name, mark
+  and colour — they are one decision about one thing. The notebook's setting
+  governs the notebook's own list; a chapter is a place someone made and filled,
+  so a reference chapter can stay alphabetical while the notebook around it stays
+  as it was arranged. It starts in the hand-made order, and a chapter put in one
+  of the others loses its lines and its handles exactly as the notebook does —
+  neither means anything against an order the app is choosing.
+
+**Fixed**
+- **A line still would not go under another line.** The comparator was only half
+  of it. The write was then thrown away by the "did anything change?" test, which
+  **sorted** the separators before comparing them — to ignore the other chapters'
+  lines riding along in the same field — and a sorted comparison cannot see a
+  sequence. Two lines in one gap carry the same position, so swapping them changes
+  nothing else. It compares this list's own lines, in order.
+- **An open chapter swelled while rearranging.** The strips at the two ends of its
+  list stood open for the whole of the mode, adding half a finger of empty space
+  inside every chapter — which read as though the notes in it had grown. They are
+  thin now, and only there while something is actually being carried.
+
+---
+
 ## 2026-08-17 — A chapter is a list too, and deleting stops moving things
 
 **Images** — web `sha256:c1bcdcc4…`, server `sha256:6c9af404…`