diff --git a/site/brand/README.md b/site/brand/README.md
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+++ b/site/brand/README.md
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+# site/brand -- the wikis' banner
+
+The top bar of both XWikis shows the starshipOS wordmark, not XWiki's logo, and the browser tab's
+title ends "- StarshipOS" (Captain Bob, 2026-11-07). `starshipos-com.png` and `starshipos-org.png`
+are the wordmark (Exo 2, white with an orange "OS", transparent), rendered at 2x.
+
+```
+XWIKI_USER=rajames XWIKI_PASSWORD=... site/brand/install.sh https://starshipos-f18.com starshipos-com.png
+XWIKI_USER=rajames XWIKI_PASSWORD=... site/brand/install.sh https://starshipos-f18.org starshipos-org.png
+```
+
+The logo belongs to the colour theme, so this makes one of our own, `FlamingoThemes.StarshipOS` (a
+copy of the stock Iceberg with the wordmark), and makes it the wiki's. To undo: set the wiki's
+colour theme back to Iceberg (Administration, Look & Feel, Themes).
diff --git a/site/brand/install.sh b/site/brand/install.sh
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+++ b/site/brand/install.sh
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+#!/bin/bash
+# install.sh -- the wiki's banner says StarshipOS, not XWiki (Captain Bob, 2026-11-07: "The banner
+# XWiki should not say that").
+#
+#   site/brand/install.sh https://starshipos-f18.com starshipos-com.png
+#   site/brand/install.sh https://starshipos-f18.org starshipos-org.png
+#
+# In XWiki 17 the top bar's logo is the colour theme's. This makes a colour theme of our own,
+# FlamingoThemes.StarshipOS -- a copy of the stock Iceberg with our wordmark as its logo -- and
+# makes it the wiki's; the stock theme is not touched (set colorTheme back to
+# FlamingoThemes.Iceberg to undo). It also makes the browser tab's title "<page> - StarshipOS".
+# Run again after changing the wordmark: the logo is replaced. XWIKI_USER and XWIKI_PASSWORD as for
+# site/*/install.sh. Everything goes as XML: XWiki refuses form and plain-text writes without its
+# form token.
+set -euo pipefail
+cd "$(dirname "$0")"
+base=${1:?usage: install.sh <wiki URL> <logo.png>}
+logo=${2:?usage: install.sh <wiki URL> <logo.png>}
+rest="$base/rest/wikis/xwiki/spaces"
+auth=(-u "${XWIKI_USER:?set XWIKI_USER}:${XWIKI_PASSWORD:?set XWIKI_PASSWORD}")
+theme="$rest/FlamingoThemes/pages/StarshipOS"
+x() { curl -fsS -m 60 "${auth[@]}" "$@"; }
+prop() {        # prop <object URL> <name> <value>: set one property
+    x -o /dev/null -w "  $2: %{http_code}\n" -X PUT -H 'Content-Type: application/xml' \
+      --data-binary "$(python3 -c '
+import sys
+from xml.sax.saxutils import escape
+print("<property xmlns=\"http://www.xwiki.org\" name=\"%s\"><value>%s</value></property>" % (escape(sys.argv[1]), escape(sys.argv[2])))' "$2" "$3")" \
+      "$1/properties/$2"
+}
+
+echo "=== $base: the colour theme FlamingoThemes.StarshipOS"
+x -o /dev/null -w "  page: %{http_code}\n" -X PUT -H 'Content-Type: application/xml' --data-binary \
+  '<page xmlns="http://www.xwiki.org"><title>StarshipOS</title><syntax>xwiki/2.1</syntax><content>{{include reference="FlamingoThemesCode.ThemeSheet"/}}</content></page>' \
+  "$theme"
+x -o /dev/null -w "  logo $logo: %{http_code}\n" -X PUT -H 'Content-Type: image/png' --data-binary "@$logo" \
+  "$theme/attachments/$logo"
+have=$(x -H 'Accept: application/json' "$theme/objects/FlamingoThemesCode.ThemeClass" |
+       python3 -c 'import json,sys; print(len(json.load(sys.stdin).get("objectSummaries") or []))')
+if [ "$have" = 0 ]; then
+    # Iceberg's theme object, every property as it is, posted to our page
+    x -H 'Accept: application/xml' "$rest/FlamingoThemes/pages/Iceberg/objects/FlamingoThemesCode.ThemeClass/0" |
+      x -o /dev/null -w "  theme object, from Iceberg: %{http_code}\n" -X POST -H 'Content-Type: application/xml' \
+        --data-binary @- "$theme/objects"
+fi
+prop "$theme/objects/FlamingoThemesCode.ThemeClass/0" logo "$logo"
+prop "$theme/objects/FlamingoThemesCode.ThemeClass/0" logo-description "StarshipOS"
+
+echo "=== the wiki's preferences"
+prefs="$rest/XWiki/pages/XWikiPreferences/objects/XWiki.XWikiPreferences/0"
+prop "$prefs" colorTheme "FlamingoThemes.StarshipOS"
+prop "$prefs" title "\$tdoc.getRenderedTitle('plain/1.0') - StarshipOS"
+
+echo "=== check, as a guest"
+page=$(curl -sS -m 60 "$base/bin/login/XWiki/XWikiLogin")     # a page that shows the chrome to a guest
+case "$page" in *"FlamingoThemes/StarshipOS/$logo"*) echo "  the banner's logo: ours";; *) echo "  the banner's logo: NOT ours" >&2; exit 1;; esac
+case "$page" in *"- StarshipOS</title>"*) echo "  the tab's title: ends - StarshipOS";; *) echo "  the tab's title: NOT ours" >&2; exit 1;; esac
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