feat(hub): Videos and Music list their cards a page at a time

Previous/next arrows in the pinned toolbar, on group pages and in Search.
Page size is an account preference (Settings → Defaults), 50 by default,
10 to 200 in steps of 10.

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

1 files changed, 9 insertions, 0 deletions

diff --git a/docs/MESHBAY_DESIGN.md b/docs/MESHBAY_DESIGN.md
index 4cac3ac..6b48300 100644
--- a/docs/MESHBAY_DESIGN.md
+++ b/docs/MESHBAY_DESIGN.md
@@ -2214,6 +2214,15 @@ service switched off node-wide. The mode toggle is a **per-device display
 preference** in local storage — it has no authority implication, so it needs none
 of the signed-op treatment.
 
+**A library is read a page at a time**, in Videos and Music alike, on the group
+page and in Search: the pinned toolbar carries previous/next arrows and the range
+shown, and a page is a slice of exactly what the mode would otherwise draw, in the
+same order (`pager.js`). The size — 50 by default, 10 to 200 in steps of 10 — is a
+**per-account preference on the hub** (`media_page_size`, behind the same
+allowlist as the others), because it describes the reader and not the group's
+content (§1.3). Show merging (below) runs before the page is cut, so a merged show
+counts as one card.
+
 **Scoping to folders is not a display preference**, because it decides what *every*
 member's tab shows. It is a per-group setting changed by a signed op, broadcast to
 connected members, and **validated before a signature is requested**: a candidate