Pair headed gizmo announcements two to a row, split by text length

Headed gizmo boxes used to share a row equally, up to three of them.
Now placeNotices pairs consecutive ones in the main column and gives the
pair one of the fixed splits — 25/75, 33/67, 50/50, 67/33, 75/25 —
nearest the ratio of the text each shows, so the wordier box gets the
room. The bases add up to 90% so a third box never joins the row, and a
side column, too narrow for two, stacks them.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Sd8UPWrvyYCLj97JexNw3A

1 files changed, 58 insertions, 3 deletions

diff --git a/internal/web/layout.go b/internal/web/layout.go
index 6f5c84f..91728ed 100644
--- a/internal/web/layout.go
+++ b/internal/web/layout.go
@@ -1,9 +1,12 @@
 package web
 
 import (
+	"html"
+	"math"
 	"net/url"
 	"strings"
 	"time"
+	"unicode/utf8"
 
 	"github.com/gramanas/blogspace/internal/i18n"
 	"github.com/gramanas/blogspace/internal/store"
@@ -243,17 +246,69 @@ func groupArchive(posts []store.PostRef) []ArchiveYear {
 	return years
 }
 
+// Notice is an announcement placed on the page: the section plus, for a
+// headed gizmo box sharing a row with the next one, its share of the row.
+type Notice struct {
+	store.Section
+	Width int // 0 = the whole row; else one of rowShares, in percent
+}
+
+// rowShares are the widths two boxes on one row can take: the longer text
+// gets the bigger share, and the pair always adds up to 100.
+var rowShares = []int{25, 33, 50, 67, 75}
+
 // placeNotices groups announcements by placement ("left-top", "main-bottom", …).
 // Ones meant for a side column that is not laid out go to the main column instead.
-func placeNotices(secs []store.Section, l Layout) map[string][]store.Section {
-	out := map[string][]store.Section{}
+// In each group, headed gizmo boxes are paired up, two to a row, and the
+// pair's widths are set by how much text each carries (main column only —
+// a side column stacks them).
+func placeNotices(secs []store.Section, l Layout) map[string][]Notice {
+	out := map[string][]Notice{}
 	for _, sec := range secs {
 		col := sec.Column()
 		if (col == "left" && !l.HasLeft) || (col == "right" && !l.HasRight) {
 			col = "main"
 		}
 		key := col + "-" + sec.Position()
-		out[key] = append(out[key], sec)
+		out[key] = append(out[key], Notice{Section: sec})
+	}
+	for key, ns := range out {
+		if strings.HasPrefix(key, "main-") {
+			pairNotices(ns)
+		}
 	}
 	return out
 }
+
+// pairNotices gives every two consecutive headed gizmo boxes their row shares.
+func pairNotices(ns []Notice) {
+	for i := 0; i+1 < len(ns); i++ {
+		if !ns[i].pairable() || !ns[i+1].pairable() {
+			continue
+		}
+		ns[i].Width, ns[i+1].Width = shareRow(noticeLen(ns[i]), noticeLen(ns[i+1]))
+		i++
+	}
+}
+
+func (n Notice) pairable() bool { return n.Style == "gizmo" && n.Title != "" }
+
+// noticeLen is how much text a box shows: its title and body, tags stripped.
+func noticeLen(n Notice) int {
+	return utf8.RuneCountInString(n.Title) + utf8.RuneCountInString(html.UnescapeString(stripTags.Sanitize(n.BodyHTML)))
+}
+
+// shareRow picks the pair of rowShares nearest to the two lengths' ratio.
+func shareRow(a, b int) (int, int) {
+	if a+b == 0 {
+		return 50, 50
+	}
+	want := float64(a) * 100 / float64(a+b)
+	best := 50
+	for _, s := range rowShares {
+		if math.Abs(float64(s)-want) < math.Abs(float64(best)-want) {
+			best = s
+		}
+	}
+	return best, 100 - best
+}