From 6424191145503198ab957fa32d9cb801cd317359 Mon Sep 17 00:00:00 2001
From: Michiel Borkent <michielborkent@gmail.com>
Date: Mon, 11 Aug 2025 12:43:02 +0200
Subject: [PATCH 01/24] wip [skip ci]

---
 bb.edn                            | 2 +-
 src/nextjournal/clerk/builder.clj | 4 +++-
 src/nextjournal/clerk/render.cljs | 9 +++++++--
 3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/bb.edn b/bb.edn
index efc2c9548..8b55601d6 100644
--- a/bb.edn
+++ b/bb.edn
@@ -20,7 +20,7 @@
 
   build:js {:doc "Builds JS"
             :depends [yarn-install]
-            :task (clojure "-M:sci:demo:dev release viewer")}
+            :task (apply clojure "-M:sci:demo:dev release viewer" *command-line-args*)}
 
   build+upload-viewer-resources {:doc "Refreshes assets stored on CDN (google storage)"
                                  :extra-paths ["src"]
diff --git a/src/nextjournal/clerk/builder.clj b/src/nextjournal/clerk/builder.clj
index 186f0a70d..debaf98a4 100644
--- a/src/nextjournal/clerk/builder.clj
+++ b/src/nextjournal/clerk/builder.clj
@@ -193,6 +193,7 @@
         in (str "import '" viewer-js "';"
                 "globalThis.CLERK_SSR = true;"
                 "console.log(nextjournal.clerk.sci_env.ssr(" (pr-str (pr-str state)) "))")]
+    (spit "in.mjs" in)
     (sh {:in in}
         "node"
         "--abort-on-uncaught-exception"
@@ -390,11 +391,12 @@
   (build-static-app! {:index "notebooks/document_linking.clj"
                       :paths ["notebooks/viewers/html.clj" "notebooks/rule_30.clj"]})
 
+  ;; document is not defined
   (build-static-app! {:ssr? true
                       :exclude-js? true
                       ;; test against cljs release `bb build:js`
                       :resource->url {"/js/viewer.js" "./build/viewer.js"}
-                      :index "notebooks/rule_30.clj"})
+                      :index "notebooks/scratch.clj"})
 
   (build-static-app! {:ssr? true
                       :exclude-js? true
diff --git a/src/nextjournal/clerk/render.cljs b/src/nextjournal/clerk/render.cljs
index 9cc5b252a..f0a525348 100644
--- a/src/nextjournal/clerk/render.cljs
+++ b/src/nextjournal/clerk/render.cljs
@@ -21,7 +21,8 @@
             [reagent.ratom :as ratom]
             [sci.core :as sci]
             [sci.ctx-store]
-            [shadow.cljs.modern :refer [defclass]]))
+            [shadow.cljs.modern :refer [defclass]]
+            [shadow.esm :as esm]))
 
 (r/set-default-compiler! (r/create-compiler {:function-components true}))
 
@@ -981,7 +982,11 @@
         default-loading-view))))
 
 (defn render-katex [tex-string {:keys [inline?]}]
-  (let [katex (hooks/use-d3-require "katex@0.16.4")]
+  (let [katex (if (some-> (unchecked-get js/globalThis "process")
+                          (unchecked-get "versions")
+                          (unchecked-get "node"))
+                (hooks/use-dynamic-import "katex@0.16.4")
+                (hooks/use-d3-require "katex@0.16.4"))]
     (if katex
       [:span {:dangerouslySetInnerHTML (r/unsafe-html (.renderToString katex tex-string (j/obj :displayMode (not inline?) :throwOnError false)))}]
       default-loading-view)))

From 9477d99eac12aa2e77d2df6a266313fed943511f Mon Sep 17 00:00:00 2001
From: Michiel Borkent <michielborkent@gmail.com>
Date: Mon, 11 Aug 2025 14:21:50 +0200
Subject: [PATCH 02/24] wip [skip ci]

---
 src/nextjournal/clerk/builder.clj | 2 ++
 src/nextjournal/clerk/render.cljs | 2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/nextjournal/clerk/builder.clj b/src/nextjournal/clerk/builder.clj
index debaf98a4..bc0b0a31b 100644
--- a/src/nextjournal/clerk/builder.clj
+++ b/src/nextjournal/clerk/builder.clj
@@ -191,6 +191,8 @@
                       tmp)
                     viewer-js)
         in (str "import '" viewer-js "';"
+                "import katex from \"katex\";"
+                "globalThis.clerk$katex = katex;"
                 "globalThis.CLERK_SSR = true;"
                 "console.log(nextjournal.clerk.sci_env.ssr(" (pr-str (pr-str state)) "))")]
     (spit "in.mjs" in)
diff --git a/src/nextjournal/clerk/render.cljs b/src/nextjournal/clerk/render.cljs
index f0a525348..e95161bd9 100644
--- a/src/nextjournal/clerk/render.cljs
+++ b/src/nextjournal/clerk/render.cljs
@@ -985,7 +985,7 @@
   (let [katex (if (some-> (unchecked-get js/globalThis "process")
                           (unchecked-get "versions")
                           (unchecked-get "node"))
-                (hooks/use-dynamic-import "katex@0.16.4")
+                (unchecked-get js/globalThis "clerk$katex")
                 (hooks/use-d3-require "katex@0.16.4"))]
     (if katex
       [:span {:dangerouslySetInnerHTML (r/unsafe-html (.renderToString katex tex-string (j/obj :displayMode (not inline?) :throwOnError false)))}]

From b9f9f3d0bc1aba16b89086bf97a9528385ec781f Mon Sep 17 00:00:00 2001
From: Michiel Borkent <michielborkent@gmail.com>
Date: Mon, 11 Aug 2025 17:22:13 +0200
Subject: [PATCH 03/24] new katex file

---
 shadow-cljs.edn                    | 4 +++-
 src/nextjournal/clerk/sci_env.cljs | 3 +--
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/shadow-cljs.edn b/shadow-cljs.edn
index 01ac70f3d..2ee0c45e7 100644
--- a/shadow-cljs.edn
+++ b/shadow-cljs.edn
@@ -8,7 +8,9 @@
                    :compiler-options {:source-map true}
                    :dev {:modules {:viewer {:entries [devtools]}}}
                    :modules {:viewer {:entries [nextjournal.clerk.sci-env
-                                                nextjournal.clerk.trim-image]}}
+                                                nextjournal.clerk.trim-image]}
+                             :katex {:entries ["katex"]
+                                     :depends-on #{:viewer}}}
                    :js-options {:output-feature-set :es8}
                    :build-hooks [(shadow.cljs.build-report/hook
                                   {:output-to "report.html" :print-table true})]}}}
diff --git a/src/nextjournal/clerk/sci_env.cljs b/src/nextjournal/clerk/sci_env.cljs
index 7e6fac134..5224e8bb7 100644
--- a/src/nextjournal/clerk/sci_env.cljs
+++ b/src/nextjournal/clerk/sci_env.cljs
@@ -8,7 +8,6 @@
             ["@lezer/highlight" :as lezer-highlight]
             ["@nextjournal/lang-clojure" :as lang-clojure]
             ["framer-motion" :as framer-motion]
-            ["katex" :as katex]
             ["react" :as react]
             ["react-dom" :as react-dom]
             ["w3c-keyname" :as w3c-keyname]
@@ -160,7 +159,7 @@
              "@lezer/highlight" lezer-highlight
              "@nextjournal/lang-clojure" lang-clojure
              "framer-motion" framer-motion
-             "katex" katex
+             #_#_"katex" katex
              "react" react
              "react-dom" react-dom
              "w3c-keyname" w3c-keyname}

From bf1c5437b469d1b50172f43293da31903834d9a2 Mon Sep 17 00:00:00 2001
From: Michiel Borkent <michielborkent@gmail.com>
Date: Mon, 11 Aug 2025 20:16:16 +0200
Subject: [PATCH 04/24] wip

---
 shadow-cljs.edn                   | 5 +++--
 src/nextjournal/clerk/builder.clj | 6 +++---
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/shadow-cljs.edn b/shadow-cljs.edn
index 2ee0c45e7..5ae6544d0 100644
--- a/shadow-cljs.edn
+++ b/shadow-cljs.edn
@@ -9,8 +9,9 @@
                    :dev {:modules {:viewer {:entries [devtools]}}}
                    :modules {:viewer {:entries [nextjournal.clerk.sci-env
                                                 nextjournal.clerk.trim-image]}
-                             :katex {:entries ["katex"]
-                                     :depends-on #{:viewer}}}
+                             :katex {:entries [#_katex nextjournal.clerk.katex]
+                                     :depends-on #{:viewer}
+                                     :exports {renderToString nextjournal.clerk.katex/renderToString}}}
                    :js-options {:output-feature-set :es8}
                    :build-hooks [(shadow.cljs.build-report/hook
                                   {:output-to "report.html" :print-table true})]}}}
diff --git a/src/nextjournal/clerk/builder.clj b/src/nextjournal/clerk/builder.clj
index bc0b0a31b..2389c37d8 100644
--- a/src/nextjournal/clerk/builder.clj
+++ b/src/nextjournal/clerk/builder.clj
@@ -191,11 +191,11 @@
                       tmp)
                     viewer-js)
         in (str "import '" viewer-js "';"
-                "import katex from \"katex\";"
-                "globalThis.clerk$katex = katex;"
+                #_"import katex from \"katex\";"
+                #_"globalThis.clerk$katex = katex;"
                 "globalThis.CLERK_SSR = true;"
                 "console.log(nextjournal.clerk.sci_env.ssr(" (pr-str (pr-str state)) "))")]
-    (spit "in.mjs" in)
+    #_(spit "in.mjs" in)
     (sh {:in in}
         "node"
         "--abort-on-uncaught-exception"

From 5bba429f9c2791f38db52905c3a1118be682a569 Mon Sep 17 00:00:00 2001
From: Michiel Borkent <michielborkent@gmail.com>
Date: Mon, 11 Aug 2025 20:16:24 +0200
Subject: [PATCH 05/24] wip

---
 src/nextjournal/clerk/katex.cljs | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 src/nextjournal/clerk/katex.cljs

diff --git a/src/nextjournal/clerk/katex.cljs b/src/nextjournal/clerk/katex.cljs
new file mode 100644
index 000000000..c8710d288
--- /dev/null
+++ b/src/nextjournal/clerk/katex.cljs
@@ -0,0 +1,5 @@
+(ns nextjournal.clerk.katex
+  (:require ["katex" :as katex]))
+
+(defn renderToString [s]
+  (katex/renderToString s))

From 39b73a0acf0b29ff8fef70ff462f170c21026a3f Mon Sep 17 00:00:00 2001
From: Michiel Borkent <michielborkent@gmail.com>
Date: Mon, 11 Aug 2025 20:20:59 +0200
Subject: [PATCH 06/24] kondo

---
 src/nextjournal/clerk/render.cljs | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/nextjournal/clerk/render.cljs b/src/nextjournal/clerk/render.cljs
index e95161bd9..2233add1b 100644
--- a/src/nextjournal/clerk/render.cljs
+++ b/src/nextjournal/clerk/render.cljs
@@ -21,8 +21,7 @@
             [reagent.ratom :as ratom]
             [sci.core :as sci]
             [sci.ctx-store]
-            [shadow.cljs.modern :refer [defclass]]
-            [shadow.esm :as esm]))
+            [shadow.cljs.modern :refer [defclass]]))
 
 (r/set-default-compiler! (r/create-compiler {:function-components true}))
 

From 13d1f80d9138487188d4190641338a38dd8a2509 Mon Sep 17 00:00:00 2001
From: Michiel Borkent <michielborkent@gmail.com>
Date: Tue, 12 Aug 2025 16:09:31 +0200
Subject: [PATCH 07/24] Bump markdown

---
 deps.edn | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/deps.edn b/deps.edn
index b0df4b976..2fe085c69 100644
--- a/deps.edn
+++ b/deps.edn
@@ -6,7 +6,7 @@
         weavejester/dependency {:mvn/version "0.2.1"}
         com.nextjournal/beholder {:mvn/version "1.0.3"}
         org.flatland/ordered {:mvn/version "1.15.12"}
-        io.github.nextjournal/markdown {:mvn/version "0.7.186"}
+        io.github.nextjournal/markdown {:mvn/version "0.7.189"}
         babashka/process {:mvn/version "0.4.16"}
         io.github.nextjournal/dejavu {:git/sha "7276cd9cec1bad001d595b52cee9e83a60d43bf0"}
         io.github.babashka/sci.nrepl {:mvn/version "0.0.2"}

From 31427bbf60c57d34226d0441f881f515f97d3c22 Mon Sep 17 00:00:00 2001
From: Michiel Borkent <michielborkent@gmail.com>
Date: Tue, 12 Aug 2025 16:23:43 +0200
Subject: [PATCH 08/24] add katex to entries

---
 shadow-cljs.edn | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/shadow-cljs.edn b/shadow-cljs.edn
index 5ae6544d0..68cb9b074 100644
--- a/shadow-cljs.edn
+++ b/shadow-cljs.edn
@@ -9,7 +9,7 @@
                    :dev {:modules {:viewer {:entries [devtools]}}}
                    :modules {:viewer {:entries [nextjournal.clerk.sci-env
                                                 nextjournal.clerk.trim-image]}
-                             :katex {:entries [#_katex nextjournal.clerk.katex]
+                             :katex {:entries [katex nextjournal.clerk.katex]
                                      :depends-on #{:viewer}
                                      :exports {renderToString nextjournal.clerk.katex/renderToString}}}
                    :js-options {:output-feature-set :es8}

From 5c8065c734606d1bc1b4d2c5c58ef7af3d431f4d Mon Sep 17 00:00:00 2001
From: Michiel Borkent <michielborkent@gmail.com>
Date: Tue, 12 Aug 2025 21:03:17 +0200
Subject: [PATCH 09/24] wip [skip ci]

---
 src/nextjournal/clerk/view.clj | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/src/nextjournal/clerk/view.clj b/src/nextjournal/clerk/view.clj
index 0d2a41c54..b2f588f4e 100644
--- a/src/nextjournal/clerk/view.clj
+++ b/src/nextjournal/clerk/view.clj
@@ -2,15 +2,32 @@
   (:require [clojure.java.io :as io]
             [clojure.string :as str]
             [hiccup.page :as hiccup]
+            [nextjournal.clerk.cljs-libs :as cljs-libs]
             [nextjournal.clerk.viewer :as v]
-            [nextjournal.clerk.cljs-libs :as cljs-libs])
+            [nextjournal.clerk.walk :as w])
   (:import (java.net URI)))
 
+(def !state (atom #{}))
+
+(defn viewer-names [state]
+  (prn :state...)
+  (def s state)
+  (let []
+    (w/postwalk (fn [v]
+                  (if-let [viewer (v/get-safe v :nextjournal/viewer)]
+                    (do (swap! !state conj (:name viewer))
+                        v)
+                    v))
+                state)
+    (def x @!state)
+    state))
+
 (defn doc->viewer
   ([doc] (doc->viewer {} doc))
   ([opts {:as doc :keys [ns file]}]
    (binding [*ns* ns]
-     (-> (merge doc opts) v/notebook v/present (cljs-libs/prepend-required-cljs opts)))))
+     (-> (merge doc opts) v/notebook v/present (cljs-libs/prepend-required-cljs opts)
+         (viewer-names)))))
 
 #_(doc->viewer (nextjournal.clerk/eval-file "notebooks/hello.clj"))
 #_(nextjournal.clerk/show! "notebooks/test.clj")

From 2a5493937900676f27117348148f0b6d0a268b69 Mon Sep 17 00:00:00 2001
From: Michiel Borkent <michielborkent@gmail.com>
Date: Mon, 18 Aug 2025 14:33:14 +0200
Subject: [PATCH 10/24] wip

---
 dev/nextjournal/clerk/ssr.clj     | 67 -------------------------------
 src/nextjournal/clerk/builder.clj | 13 +++---
 src/nextjournal/clerk/view.clj    |  9 +----
 3 files changed, 10 insertions(+), 79 deletions(-)
 delete mode 100644 dev/nextjournal/clerk/ssr.clj

diff --git a/dev/nextjournal/clerk/ssr.clj b/dev/nextjournal/clerk/ssr.clj
deleted file mode 100644
index a958483e2..000000000
--- a/dev/nextjournal/clerk/ssr.clj
+++ /dev/null
@@ -1,67 +0,0 @@
-(ns nextjournal.clerk.ssr
-  "Server-side-rendering using `reagent.dom.server` on GraalJS.
-
-  Status: working in GraalJS `org.graalvm.js/js {:mvn/version \"22.3.0\"}`
-
-  To try this ad the dep above to e.g. the `:sci` alias."
-  (:require [clojure.java.io :as io]
-            [clojure.edn :as edn]
-            [clojure.string :as str]
-            [nextjournal.clerk.config :as config])
-  (:import (org.graalvm.polyglot Context Source)))
-
-(def context-builder
-  (doto (Context/newBuilder (into-array ["js"]))
-    (.option "js.timer-resolution" "1")
-    (.option "js.java-package-globals" "false")
-    (.out System/out)
-    (.err System/err)
-    (.allowAllAccess true)
-    (.allowNativeAccess true)))
-
-(def context (.build context-builder))
-
-(defn execute-fn [context fn & args]
-  (let [fn-ref (.eval context "js" fn)
-        args (into-array Object args)]
-    (assert (.canExecute fn-ref) (str "cannot execute " fn))
-    (.execute fn-ref args)))
-
-(defn viewer-js-path []
-  (@config/!asset-map "/js/viewer.js")
-  ;; uncomment the following to test against a local js bundle
-  #_"build/viewer.js")
-
-(def viewer-js-source
-  ;; run `bb build:js` on shell to generate
-  (.build (Source/newBuilder "js" (str (slurp "https://gist.githubusercontent.com/Yaffle/5458286/raw/1aa5caa5cdd9938fe0fe202357db6c6b33af24f4/TextEncoderTextDecoder.js") ;; tiny utf8 only TextEncoder polyfill
-                                       "\n"
-                                       (slurp (viewer-js-path))) "viewer.mjs")))
-
-
-(def !eval-viewer-source
-  (delay (.eval context viewer-js-source)))
-
-(defn render [edn-string]
-  (force !eval-viewer-source)
-  (execute-fn context "nextjournal.clerk.sci_env.ssr" edn-string))
-
-
-(comment
-  (do
-    (require '[nextjournal.clerk :as clerk]
-             '[nextjournal.clerk.eval :as eval]
-             '[nextjournal.clerk.builder :as builder]
-             '[nextjournal.clerk.view :as view])
-
-    (defn file->static-app-opts [file]
-      (-> (eval/eval-file file)
-          (as-> doc (assoc doc :viewer (view/doc->viewer {} doc)))
-          (as-> doc+viewer (builder/build-static-app-opts (builder/process-build-opts {:index file}) [doc+viewer]))))
-
-    (spit "build/static_app_state_hello.edn" (pr-str (file->static-app-opts "notebooks/hello.clj")))
-    (spit "build/static_app_state_rule_30.edn" (pr-str (file->static-app-opts "notebooks/rule_30.clj")))
-
-    (time (render (slurp "build/static_app_state_hello.edn")))))
-
-
diff --git a/src/nextjournal/clerk/builder.clj b/src/nextjournal/clerk/builder.clj
index 2389c37d8..27de2f017 100644
--- a/src/nextjournal/clerk/builder.clj
+++ b/src/nextjournal/clerk/builder.clj
@@ -181,7 +181,9 @@
     :or {viewer-js
          ;; for local REPL testing
          "./public/js/viewer.js"}}]
-  (let [viewer-js (if (str/starts-with? viewer-js "http")
+  (def s state)
+  (let [katex? (-> state :doc :katex?)
+        viewer-js (if (str/starts-with? viewer-js "http")
                     (let [tmp (-> (fs/create-temp-file {:suffix ".mjs"})
                                   (fs/file)
                                   (fs/delete-on-exit)
@@ -191,11 +193,12 @@
                       tmp)
                     viewer-js)
         in (str "import '" viewer-js "';"
-                #_"import katex from \"katex\";"
-                #_"globalThis.clerk$katex = katex;"
+                (when katex?
+                  (str "import katex from \"katex\";"
+                       "globalThis.clerk$katex = katex;"))
                 "globalThis.CLERK_SSR = true;"
                 "console.log(nextjournal.clerk.sci_env.ssr(" (pr-str (pr-str state)) "))")]
-    #_(spit "in.mjs" in)
+    (spit "in.mjs" in)
     (sh {:in in}
         "node"
         "--abort-on-uncaught-exception"
@@ -251,7 +254,7 @@
                                           (dissoc :path->doc)
                                           cleanup))))))
     (when browse?
-      (browse/browse-url (if-let [server-url (and (= out-path "public/build") (webserver/server-url))]
+      (browse/browse-url (if-let [server-url (and (= "public/build" out-path) (webserver/server-url))]
                            (str server-url "/build/")
                            (-> index-html fs/absolutize .toString path-to-url-canonicalize))))
     {:docs docs
diff --git a/src/nextjournal/clerk/view.clj b/src/nextjournal/clerk/view.clj
index b2f588f4e..6083a7e33 100644
--- a/src/nextjournal/clerk/view.clj
+++ b/src/nextjournal/clerk/view.clj
@@ -7,20 +7,15 @@
             [nextjournal.clerk.walk :as w])
   (:import (java.net URI)))
 
-(def !state (atom #{}))
-
 (defn viewer-names [state]
-  (prn :state...)
-  (def s state)
-  (let []
+  (let [!state (atom #{})]
     (w/postwalk (fn [v]
                   (if-let [viewer (v/get-safe v :nextjournal/viewer)]
                     (do (swap! !state conj (:name viewer))
                         v)
                     v))
                 state)
-    (def x @!state)
-    state))
+    (assoc state :katex? (contains? @!state 'nextjournal.clerk.viewer/katex-viewer))))
 
 (defn doc->viewer
   ([doc] (doc->viewer {} doc))

From dda7ccb2dd3247b4525c79e335384ff542fe7199 Mon Sep 17 00:00:00 2001
From: Michiel Borkent <michielborkent@gmail.com>
Date: Mon, 18 Aug 2025 17:03:28 +0200
Subject: [PATCH 11/24] wip

---
 render/deps.edn                   |  2 +-
 src/nextjournal/clerk/builder.clj | 33 ++++++++++++++++++-------------
 2 files changed, 20 insertions(+), 15 deletions(-)

diff --git a/render/deps.edn b/render/deps.edn
index a12ba3fda..9edde0445 100644
--- a/render/deps.edn
+++ b/render/deps.edn
@@ -8,7 +8,7 @@
         io.github.babashka/sci.configs {:git/sha "8253c69a537bcc82e8ff122e5f905fe9d1e303f0"
                                         :exclusions [org.babashka/sci]}
         io.github.nextjournal/clojure-mode {:git/sha "1f55406087814a0dda6806396aa596dbe13ea302"}
-        thheller/shadow-cljs {:mvn/version "3.0.4"}
+        thheller/shadow-cljs {:mvn/version "3.2.0"}
         io.github.squint-cljs/cherry {;; :local/root "/Users/borkdude/dev/cherry"
                                       :git/sha "8de9f27"
                                       :git/tag "v0.4.26"
diff --git a/src/nextjournal/clerk/builder.clj b/src/nextjournal/clerk/builder.clj
index 27de2f017..bf370e267 100644
--- a/src/nextjournal/clerk/builder.clj
+++ b/src/nextjournal/clerk/builder.clj
@@ -176,29 +176,34 @@
         response (.send client request (java.net.http.HttpResponse$BodyHandlers/ofString))]
     (.body response)))
 
+(defn local-js [url]
+  (if (str/starts-with? url "http")
+    (let [tmp (-> (fs/create-temp-file {:suffix ".mjs"})
+                  (fs/file)
+                  (fs/delete-on-exit)
+                  str)
+          src (download-text-file url)]
+      (spit tmp src)
+      tmp)
+    url))
+
 (defn- node-ssr!
   [{:keys [viewer-js state]
     :or {viewer-js
          ;; for local REPL testing
          "./public/js/viewer.js"}}]
-  (def s state)
   (let [katex? (-> state :doc :katex?)
-        viewer-js (if (str/starts-with? viewer-js "http")
-                    (let [tmp (-> (fs/create-temp-file {:suffix ".mjs"})
-                                  (fs/file)
-                                  (fs/delete-on-exit)
-                                  str)
-                          src (download-text-file viewer-js)]
-                      (spit tmp src)
-                      tmp)
-                    viewer-js)
+        [viewer-js katex-js] [(local-js viewer-js)
+                              (when katex?
+                                (local-js (str/replace viewer-js #"viewer.js$" "katex.js")))]
         in (str "import '" viewer-js "';"
                 (when katex?
-                  (str "import katex from \"katex\";"
-                       "globalThis.clerk$katex = katex;"))
+                  (format (str "import * as katex from \"%s\";"
+                               "globalThis.clerk$katex = katex;")
+                          katex-js))
                 "globalThis.CLERK_SSR = true;"
-                "console.log(nextjournal.clerk.sci_env.ssr(" (pr-str (pr-str state)) "))")]
-    (spit "in.mjs" in)
+                "console.log(nextjournal.clerk.sci_env.ssr(" (pr-str (pr-str state )) "))")]
+    #_(spit "in.mjs" in)
     (sh {:in in}
         "node"
         "--abort-on-uncaught-exception"

From f1ab3cbf23822bd097641d26c35db298b7526ca8 Mon Sep 17 00:00:00 2001
From: Michiel Borkent <michielborkent@gmail.com>
Date: Mon, 18 Aug 2025 20:58:54 +0200
Subject: [PATCH 12/24] wip

---
 notebooks/viewers/katex.clj | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)
 create mode 100644 notebooks/viewers/katex.clj

diff --git a/notebooks/viewers/katex.clj b/notebooks/viewers/katex.clj
new file mode 100644
index 000000000..2c1456d5c
--- /dev/null
+++ b/notebooks/viewers/katex.clj
@@ -0,0 +1,16 @@
+;; # Katex
+
+(ns katex
+  (:require [nextjournal.clerk]
+            [nextjournal.clerk.viewer]))
+
+;; Inline formula: $x^2$
+
+
+;; Block level formula:
+;; $$x^2$$
+
+;; Manual viewer:
+(nextjournal.clerk/with-viewer
+  nextjournal.clerk.viewer/katex-viewer "x^2")
+

From e58564d4ad51b5a0636a1dfa54f817f23c6260eb Mon Sep 17 00:00:00 2001
From: Michiel Borkent <michielborkent@gmail.com>
Date: Tue, 19 Aug 2025 13:41:13 +0200
Subject: [PATCH 13/24] wip

---
 src/nextjournal/clerk/builder.clj | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/src/nextjournal/clerk/builder.clj b/src/nextjournal/clerk/builder.clj
index bf370e267..36210b54d 100644
--- a/src/nextjournal/clerk/builder.clj
+++ b/src/nextjournal/clerk/builder.clj
@@ -176,13 +176,17 @@
         response (.send client request (java.net.http.HttpResponse$BodyHandlers/ofString))]
     (.body response)))
 
-(defn local-js [url]
+(defn local-js [url tmp-dir]
   (if (str/starts-with? url "http")
-    (let [tmp (-> (fs/create-temp-file {:suffix ".mjs"})
-                  (fs/file)
+    (let [tmp (-> tmp-dir
+                  (fs/file (-> (fs/file-name url)
+                               (str/split  #"\?")
+                               (first)
+                               (str/replace #".js$" ".mjs")))
                   (fs/delete-on-exit)
                   str)
-          src (download-text-file url)]
+          src (download-text-file url)
+          src (str/replace src "viewer.js" "viewer.mjs")]
       (spit tmp src)
       tmp)
     url))
@@ -192,10 +196,11 @@
     :or {viewer-js
          ;; for local REPL testing
          "./public/js/viewer.js"}}]
-  (let [katex? (-> state :doc :katex?)
-        [viewer-js katex-js] [(local-js viewer-js)
+  (let [tmp-dir (fs/create-temp-dir)
+        katex? (-> state :doc :katex?)
+        [viewer-js katex-js] [(local-js viewer-js tmp-dir)
                               (when katex?
-                                (local-js (str/replace viewer-js #"viewer.js$" "katex.js")))]
+                                (local-js (str/replace viewer-js "viewer.js" "katex.js") tmp-dir))]
         in (str "import '" viewer-js "';"
                 (when katex?
                   (format (str "import * as katex from \"%s\";"

From 2b3546814916a50c6c3f7369d4e1112a2a4dbfdc Mon Sep 17 00:00:00 2001
From: Michiel Borkent <michielborkent@gmail.com>
Date: Tue, 19 Aug 2025 13:47:34 +0200
Subject: [PATCH 14/24] ssr

---
 .github/workflows/main.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 403e42a16..33512eaa2 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -251,7 +251,7 @@ jobs:
         run: echo $(yarn global dir)/node_modules
 
       - name: 🧪 Build Rule 30 Notebook with SSR
-        run: NODE_PATH=$(yarn global dir)/node_modules clojure -J-Dclojure.main.report=stdout -X:demo:nextjournal/clerk :git/sha '"${{ github.sha }}"' :git/url '"https://github.com/nextjournal/clerk"' :index '"notebooks/rule_30.clj"' :paths [] :ssr true :compile-css true :exclude-js true
+        run: NODE_PATH=$(yarn global dir)/node_modules clojure -J-Dclojure.main.report=stdout -X:demo:nextjournal/clerk :git/sha '"${{ github.sha }}"' :git/url '"https://github.com/nextjournal/clerk"' :paths '["notebooks/rule_30.clj" "notebooks/viewers/katex.clj"]' :ssr true :compile-css true :exclude-js true
 
       - name: 🔐 Google Auth
         uses: google-github-actions/auth@v2.1.6

From aa753720ed2618b2f06e4bb9b82d0b6f412d5a2e Mon Sep 17 00:00:00 2001
From: Michiel Borkent <michielborkent@gmail.com>
Date: Tue, 19 Aug 2025 21:02:07 +0200
Subject: [PATCH 15/24] wip

---
 src/nextjournal/clerk/builder.clj | 22 +++++++++++++---------
 src/nextjournal/clerk/render.cljs |  3 ++-
 src/nextjournal/clerk/view.clj    |  2 ++
 3 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/src/nextjournal/clerk/builder.clj b/src/nextjournal/clerk/builder.clj
index 36210b54d..05f993ed0 100644
--- a/src/nextjournal/clerk/builder.clj
+++ b/src/nextjournal/clerk/builder.clj
@@ -206,14 +206,16 @@
                   (format (str "import * as katex from \"%s\";"
                                "globalThis.clerk$katex = katex;")
                           katex-js))
-                "globalThis.CLERK_SSR = true;"
+                "globalThis.CLERK_SSR = true;
+                new Promise((resolve) => { setTimeout(resolve, 2000)});\n"
                 "console.log(nextjournal.clerk.sci_env.ssr(" (pr-str (pr-str state )) "))")]
-    #_(spit "in.mjs" in)
-    (sh {:in in}
-        "node"
-        "--abort-on-uncaught-exception"
-        "--input-type=module"
-        "--trace-warnings")))
+    (spit "in.mjs" in)
+    (sh
+     {:out :string :in in :err :inherit}
+     "node"
+     "--abort-on-uncaught-exception"
+     "--input-type=module"
+     "--trace-warnings")))
 
 (comment
   (declare so) ;; captured in REPL in ssr! function
@@ -239,8 +241,10 @@
       (throw (ex-info (str "Clerk ssr! failed\n" out "\n" err) result)))))
 
 (defn cleanup [build-opts]
-  (select-keys build-opts
-               [:package :render-router :path->doc :current-path :resource->url :exclude-js? :index :html]))
+  (cond-> (select-keys build-opts
+                       [:package :render-router :path->doc :current-path :resource->url :exclude-js? :index :html])
+    (-> build-opts :doc :katex?)
+    (assoc :katex? true)))
 
 (defn write-static-app!
   [opts docs]
diff --git a/src/nextjournal/clerk/render.cljs b/src/nextjournal/clerk/render.cljs
index 2233add1b..f75e5f39f 100644
--- a/src/nextjournal/clerk/render.cljs
+++ b/src/nextjournal/clerk/render.cljs
@@ -987,7 +987,8 @@
                 (unchecked-get js/globalThis "clerk$katex")
                 (hooks/use-d3-require "katex@0.16.4"))]
     (if katex
-      [:span {:dangerouslySetInnerHTML (r/unsafe-html (.renderToString katex tex-string (j/obj :displayMode (not inline?) :throwOnError false)))}]
+      (let [html (.renderToString katex tex-string (j/obj :displayMode (not inline?) :throwOnError false))]
+        [:span {:dangerouslySetInnerHTML (r/unsafe-html html)}])
       default-loading-view)))
 
 (defn render-mathjax [value]
diff --git a/src/nextjournal/clerk/view.clj b/src/nextjournal/clerk/view.clj
index 6083a7e33..8d1a8194d 100644
--- a/src/nextjournal/clerk/view.clj
+++ b/src/nextjournal/clerk/view.clj
@@ -53,6 +53,8 @@
 (defn include-css+js [state]
   (list
    (include-viewer-css state)
+   (when (:katex? state)
+     (hiccup/include-css "https://cdnjs.cloudflare.com/ajax/libs/KaTeX/0.12.0/katex.min.js"))
    [:script {:type "module" :src (adjust-relative-path state (get-in state [:resource->url "/js/viewer.js"]))}]
    (hiccup/include-css "https://cdn.jsdelivr.net/npm/katex@0.13.13/dist/katex.min.css")
    [:link {:rel "preconnect" :href "https://fonts.bunny.net"}]

From 43b194b09c700f082797bfd81361da28baa732da Mon Sep 17 00:00:00 2001
From: Michiel Borkent <michielborkent@gmail.com>
Date: Tue, 19 Aug 2025 21:02:30 +0200
Subject: [PATCH 16/24] wip

---
 src/nextjournal/clerk/builder.clj | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/nextjournal/clerk/builder.clj b/src/nextjournal/clerk/builder.clj
index 05f993ed0..fde4032cf 100644
--- a/src/nextjournal/clerk/builder.clj
+++ b/src/nextjournal/clerk/builder.clj
@@ -209,7 +209,7 @@
                 "globalThis.CLERK_SSR = true;
                 new Promise((resolve) => { setTimeout(resolve, 2000)});\n"
                 "console.log(nextjournal.clerk.sci_env.ssr(" (pr-str (pr-str state )) "))")]
-    (spit "in.mjs" in)
+    #_(spit "in.mjs" in)
     (sh
      {:out :string :in in :err :inherit}
      "node"

From e923f98dd000019a669004019d8b03b753101c0e Mon Sep 17 00:00:00 2001
From: Michiel Borkent <michielborkent@gmail.com>
Date: Tue, 19 Aug 2025 21:14:53 +0200
Subject: [PATCH 17/24] fix css

---
 src/nextjournal/clerk/view.clj | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/src/nextjournal/clerk/view.clj b/src/nextjournal/clerk/view.clj
index 8d1a8194d..9cd55f543 100644
--- a/src/nextjournal/clerk/view.clj
+++ b/src/nextjournal/clerk/view.clj
@@ -50,11 +50,14 @@
                        (str/replace #"require\(.*\)" ""))]
           [:style {:type "text/tailwindcss"} (slurp (io/resource "stylesheets/viewer.css"))])))
 
+(defn include-katex-css [state]
+  (when (:katex? state)
+    (hiccup/include-css "https://cdnjs.cloudflare.com/ajax/libs/KaTeX/0.12.0/katex.min.css")))
+
 (defn include-css+js [state]
   (list
    (include-viewer-css state)
-   (when (:katex? state)
-     (hiccup/include-css "https://cdnjs.cloudflare.com/ajax/libs/KaTeX/0.12.0/katex.min.js"))
+   (include-katex-css state)
    [:script {:type "module" :src (adjust-relative-path state (get-in state [:resource->url "/js/viewer.js"]))}]
    (hiccup/include-css "https://cdn.jsdelivr.net/npm/katex@0.13.13/dist/katex.min.css")
    [:link {:rel "preconnect" :href "https://fonts.bunny.net"}]
@@ -80,7 +83,8 @@
         }"])
     (when current-path (v/open-graph-metas (-> state :path->doc (get current-path) v/->value :open-graph)))
     (if exclude-js?
-      (include-viewer-css state)
+      (list (include-viewer-css state)
+            (include-katex-css state))
       (include-css+js state))]
    [:body.dark:bg-gray-900
     [:div#clerk html]

From cc794641a58aea2d1b69f34f06935a1292388cd8 Mon Sep 17 00:00:00 2001
From: Michiel Borkent <michielborkent@gmail.com>
Date: Mon, 25 Aug 2025 15:27:19 +0200
Subject: [PATCH 18/24] Fix ui build]

---
 .github/workflows/main.yml     |  2 +-
 ui_tests/playwright_tests.cljs | 13 ++++++++++---
 ui_tests/ssr.cljs              | 10 +++++-----
 3 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 33512eaa2..5007e83aa 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -318,7 +318,7 @@ jobs:
         run: |
           bb test:static-app :sha ${{ github.sha }} :skip-install true
           bb test:static-app :skip-install true :url https://snapshots.nextjournal.com/clerk/book/${{ github.sha }}/book/index.html :index false :selector "h1:has-text(\"Book of Clerk\")"
-          bb test:static-app :skip-install true :url https://snapshots.nextjournal.com/clerk-ssr/build/${{ github.sha }}/index.html :index false :selector "h1:has-text(\"Rule 30\")"
+          bb test:static-app :skip-install true :url https://snapshots.nextjournal.com/clerk-ssr/build/${{ github.sha }}/index.html :index true
 
   deploy:
     needs: [build-and-upload-viewer-resources, test]
diff --git a/ui_tests/playwright_tests.cljs b/ui_tests/playwright_tests.cljs
index 03883fa93..522c6d65a 100644
--- a/ui_tests/playwright_tests.cljs
+++ b/ui_tests/playwright_tests.cljs
@@ -46,23 +46,30 @@
 
 (def console-errors (atom []))
 
+(def page-selectors {"notebooks/rule_30.clj" "h1:has-text(\"Rule 30\")"
+                     "notebooks/viewers/katex.clj" "span.katex"})
+
 (defn test-notebook
   ([page url]
    (println "Visiting" url)
    (p/do (goto page url)
          (.waitForLoadState page "networkidle")
-         (p/let [selector (or (:selector @!opts) "div")
+         (p/let [selector (or (:selector @!opts)
+                              "div")
                  _ (prn :selector selector)
                  loc (.locator page selector #js {:timeout 10000})
                  loc (.first loc #js {:timeout 10000})
                  _ (.waitFor loc #js {:state "visible"})
                  visible? (.isVisible loc)]
            (is visible?))))
+  ;; called from index-page-test
   ([page url link]
-   (p/let [txt (.innerText link)]
+   (p/let [txt (.innerText link)
+           selector (or (get page-selectors txt)
+                        "div")]
      (println "Visiting" (str url "#/" txt))
      (p/do (.click link)
-           (p/let [loc (.locator page "div")
+           (p/let [loc (.locator page selector)
                    loc (.first loc #js {:timeout 10000})
                    _ (.waitFor loc #js {:state "visible"})
                    visible? (.isVisible loc)]
diff --git a/ui_tests/ssr.cljs b/ui_tests/ssr.cljs
index 7651ba0d3..79fc3e0e0 100644
--- a/ui_tests/ssr.cljs
+++ b/ui_tests/ssr.cljs
@@ -3,12 +3,12 @@
 
   Use this to iterate on it, then make sure the advanced bundle works
   in Graal via `nextjournal.clerk.ssr`."
-  (:require ["./../public/js/viewer.js" :as viewer]
-            ;; the above is the dev build, the one below the relase (generate it via `bb release:js`)
+  (:require ["./../public/js/viewer.js"]
+            ;; the above is the dev build, the one below the release (generate it via `bb release:js`)
             #_["./../build/viewer.js" :as viewer]
             [babashka.cli :as cli]
-            [promesa.core :as p]
-            [nbb.core :refer [slurp]]))
+            [nbb.core :refer [slurp]]
+            [promesa.core :as p]))
 
 (defn -main [& args]
   (p/let [{:keys [file edn url]} (:opts (cli/parse-args args {:alias {:u :url :f :file}}))
@@ -16,7 +16,7 @@
                            edn edn)]
     (if edn-string
       (println (js/nextjournal.clerk.sci_env.ssr edn-string))
-      (binding [*out* *err*]
+      (binding [*print-fn* *print-err-fn*]
         (println "must provide --file or --edn arg")))))
 
 

From 7058dd46ef277bf1f1fdc2a843aa7039b49f97a2 Mon Sep 17 00:00:00 2001
From: Michiel Borkent <michielborkent@gmail.com>
Date: Mon, 25 Aug 2025 20:29:27 +0200
Subject: [PATCH 19/24] fix build

---
 deps.edn                          | 1 +
 src/nextjournal/clerk/builder.clj | 8 ++------
 src/nextjournal/clerk/viewer.cljc | 9 +++++++--
 3 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/deps.edn b/deps.edn
index 2fe085c69..f4030619e 100644
--- a/deps.edn
+++ b/deps.edn
@@ -2,6 +2,7 @@
  :deps {org.clojure/clojure {:mvn/version "1.11.1"}
         org.clojure/java.classpath {:mvn/version "1.0.0"}
         babashka/fs {:mvn/version "0.5.22"}
+        org.babashka/http-client {:mvn/version "0.4.23"}
         borkdude/edamame {:mvn/version "1.4.28"}
         weavejester/dependency {:mvn/version "0.2.1"}
         com.nextjournal/beholder {:mvn/version "1.0.3"}
diff --git a/src/nextjournal/clerk/builder.clj b/src/nextjournal/clerk/builder.clj
index fde4032cf..f79a1eab2 100644
--- a/src/nextjournal/clerk/builder.clj
+++ b/src/nextjournal/clerk/builder.clj
@@ -1,6 +1,7 @@
 (ns nextjournal.clerk.builder
   "Clerk's Static App Builder."
   (:require [babashka.fs :as fs]
+            [babashka.http-client :as http]
             [babashka.process :refer [sh]]
             [clojure.java.browse :as browse]
             [clojure.java.io :as io]
@@ -169,12 +170,7 @@
            :paths (vec (keys path->doc)))))
 
 (defn download-text-file [url]
-  (let [client (java.net.http.HttpClient/newHttpClient)
-        request (-> (java.net.http.HttpRequest/newBuilder)
-                    (.uri (java.net.URI/create url))
-                    (.build))
-        response (.send client request (java.net.http.HttpResponse$BodyHandlers/ofString))]
-    (.body response)))
+  (:body (http/get url)))
 
 (defn local-js [url tmp-dir]
   (if (str/starts-with? url "http")
diff --git a/src/nextjournal/clerk/viewer.cljc b/src/nextjournal/clerk/viewer.cljc
index fecfb0143..1debaf631 100644
--- a/src/nextjournal/clerk/viewer.cljc
+++ b/src/nextjournal/clerk/viewer.cljc
@@ -1,6 +1,7 @@
 (ns nextjournal.clerk.viewer
   (:refer-clojure :exclude [var?])
-  (:require [clojure.datafy :as datafy]
+  (:require #?(:clj [babashka.http-client :as http])
+            [clojure.datafy :as datafy]
             [clojure.pprint :as pprint]
             [clojure.set :as set]
             [clojure.string :as str]
@@ -616,7 +617,11 @@
    (defn read-image [image-or-url]
      (ImageIO/read
       (if (string? image-or-url)
-        (URL. (cond->> image-or-url (not (.getScheme (URI. image-or-url))) (str "file:")))
+        (let [scheme (.getScheme (URI. image-or-url))
+              http? (str/starts-with? scheme "http")]
+          (if http?
+            (:body (http/get image-or-url {:as :stream}))
+            (URL. (cond->> image-or-url (not scheme) (str "file:")))))
         image-or-url))))
 
 #?(:clj

From 016d0bc7c9a1bfaca9257998fdced1c9ccab564b Mon Sep 17 00:00:00 2001
From: Michiel Borkent <michielborkent@gmail.com>
Date: Mon, 25 Aug 2025 20:29:27 +0200
Subject: [PATCH 20/24] fix build

---
 deps.edn                          | 1 +
 src/nextjournal/clerk/builder.clj | 8 ++------
 src/nextjournal/clerk/viewer.cljc | 9 +++++++--
 3 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/deps.edn b/deps.edn
index b0df4b976..88f46fefb 100644
--- a/deps.edn
+++ b/deps.edn
@@ -2,6 +2,7 @@
  :deps {org.clojure/clojure {:mvn/version "1.11.1"}
         org.clojure/java.classpath {:mvn/version "1.0.0"}
         babashka/fs {:mvn/version "0.5.22"}
+        org.babashka/http-client {:mvn/version "0.4.23"}
         borkdude/edamame {:mvn/version "1.4.28"}
         weavejester/dependency {:mvn/version "0.2.1"}
         com.nextjournal/beholder {:mvn/version "1.0.3"}
diff --git a/src/nextjournal/clerk/builder.clj b/src/nextjournal/clerk/builder.clj
index 186f0a70d..fd6ea0ed2 100644
--- a/src/nextjournal/clerk/builder.clj
+++ b/src/nextjournal/clerk/builder.clj
@@ -1,6 +1,7 @@
 (ns nextjournal.clerk.builder
   "Clerk's Static App Builder."
   (:require [babashka.fs :as fs]
+            [babashka.http-client :as http]
             [babashka.process :refer [sh]]
             [clojure.java.browse :as browse]
             [clojure.java.io :as io]
@@ -169,12 +170,7 @@
            :paths (vec (keys path->doc)))))
 
 (defn download-text-file [url]
-  (let [client (java.net.http.HttpClient/newHttpClient)
-        request (-> (java.net.http.HttpRequest/newBuilder)
-                    (.uri (java.net.URI/create url))
-                    (.build))
-        response (.send client request (java.net.http.HttpResponse$BodyHandlers/ofString))]
-    (.body response)))
+  (:body (http/get url)))
 
 (defn- node-ssr!
   [{:keys [viewer-js state]
diff --git a/src/nextjournal/clerk/viewer.cljc b/src/nextjournal/clerk/viewer.cljc
index fecfb0143..1debaf631 100644
--- a/src/nextjournal/clerk/viewer.cljc
+++ b/src/nextjournal/clerk/viewer.cljc
@@ -1,6 +1,7 @@
 (ns nextjournal.clerk.viewer
   (:refer-clojure :exclude [var?])
-  (:require [clojure.datafy :as datafy]
+  (:require #?(:clj [babashka.http-client :as http])
+            [clojure.datafy :as datafy]
             [clojure.pprint :as pprint]
             [clojure.set :as set]
             [clojure.string :as str]
@@ -616,7 +617,11 @@
    (defn read-image [image-or-url]
      (ImageIO/read
       (if (string? image-or-url)
-        (URL. (cond->> image-or-url (not (.getScheme (URI. image-or-url))) (str "file:")))
+        (let [scheme (.getScheme (URI. image-or-url))
+              http? (str/starts-with? scheme "http")]
+          (if http?
+            (:body (http/get image-or-url {:as :stream}))
+            (URL. (cond->> image-or-url (not scheme) (str "file:")))))
         image-or-url))))
 
 #?(:clj

From 48e483f66d9fc76982945a141523daf584be771d Mon Sep 17 00:00:00 2001
From: Michiel Borkent <michielborkent@gmail.com>
Date: Mon, 25 Aug 2025 20:36:50 +0200
Subject: [PATCH 21/24] fix npe

---
 src/nextjournal/clerk/viewer.cljc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/nextjournal/clerk/viewer.cljc b/src/nextjournal/clerk/viewer.cljc
index 1debaf631..1fd086af1 100644
--- a/src/nextjournal/clerk/viewer.cljc
+++ b/src/nextjournal/clerk/viewer.cljc
@@ -618,7 +618,7 @@
      (ImageIO/read
       (if (string? image-or-url)
         (let [scheme (.getScheme (URI. image-or-url))
-              http? (str/starts-with? scheme "http")]
+              http? (when scheme (str/starts-with? scheme "http"))]
           (if http?
             (:body (http/get image-or-url {:as :stream}))
             (URL. (cond->> image-or-url (not scheme) (str "file:")))))

From 70e60fbd63d7b511635607af968970c393e2f736 Mon Sep 17 00:00:00 2001
From: Michiel Borkent <michielborkent@gmail.com>
Date: Mon, 25 Aug 2025 20:54:48 +0200
Subject: [PATCH 22/24] fix notebook

---
 notebooks/viewers/table.clj | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/notebooks/viewers/table.clj b/notebooks/viewers/table.clj
index 173e086c3..bdb2a1af8 100644
--- a/notebooks/viewers/table.clj
+++ b/notebooks/viewers/table.clj
@@ -1,12 +1,13 @@
 ;; # Tables 🔢
 (ns ^:nextjournal.clerk/no-cache viewers.table
-  (:require [clojure.data.csv :as csv]
+  (:require [babashka.http-client :as http]
+            [clojure.data.csv :as csv]
             [clojure.java.io :as io]
             [clojure.string :as str]
+            [honey.sql :as sql]
             [next.jdbc :as jdbc]
             [nextjournal.clerk :as clerk]
-            [nextjournal.clerk.viewer :as v]
-            [honey.sql :as sql]))
+            [nextjournal.clerk.viewer :as v]))
 
 ;; ## Empty table
 
@@ -60,8 +61,11 @@
                (-> (mapv (fn [char] (clojure.string/join "" (repeat 20 char)))
                          (map char (range 97 127))))]})
 
+(defn read-image [url]
+  (javax.imageio.ImageIO/read (:body (http/get url {:as :stream}))))
+
 ;; ## Table with images
-(clerk/table [[1 2] [3 (javax.imageio.ImageIO/read (java.net.URL. "https://nextjournal.com/data/QmeyvaR3Q5XSwe14ZS6D5WBQGg1zaBaeG3SeyyuUURE2pq?filename=thermos.gif&content-type=image/gif"))]])
+(clerk/table [[1 2] [3 (read-image "https://nextjournal.com/data/QmeyvaR3Q5XSwe14ZS6D5WBQGg1zaBaeG3SeyyuUURE2pq?filename=thermos.gif&content-type=image/gif")]])
 
 ;; ## Table within tables
 (clerk/table [[1 2] [3 (clerk/table [[1 2] [3 4]])]])
@@ -76,8 +80,8 @@
 (clerk/with-viewers (clerk/add-viewers [(assoc v/image-viewer :render-fn '(fn [blob] [:img {:width "30px" :height "30px" :src (nextjournal.clerk.viewer/url-for blob)}]))])
   (clerk/table
    {:rows (map (juxt identity dec) (range 1 100))
-    :head [(javax.imageio.ImageIO/read (java.net.URL. "https://upload.wikimedia.org/wikipedia/commons/1/17/Plus_img_364976.png"))
-           (javax.imageio.ImageIO/read (java.net.URL. "https://upload.wikimedia.org/wikipedia/commons/thumb/d/df/OCR-A_char_Hyphen-Minus.svg/543px-OCR-A_char_Hyphen-Minus.svg.png"))]}))
+    :head [(read-image "https://upload.wikimedia.org/wikipedia/commons/1/17/Plus_img_364976.png")
+           (read-image "https://upload.wikimedia.org/wikipedia/commons/thumb/d/df/OCR-A_char_Hyphen-Minus.svg/543px-OCR-A_char_Hyphen-Minus.svg.png")]}))
 
 ;; ## Custom Table Viewers
 ;; override single table components

From fa1cf4fc8255ef97539d9de44ebaba6c7ab09e1d Mon Sep 17 00:00:00 2001
From: Michiel Borkent <michielborkent@gmail.com>
Date: Mon, 1 Sep 2025 15:18:46 +0200
Subject: [PATCH 23/24] Additional fixes

---
 src/nextjournal/clerk/builder.clj | 2 +-
 src/nextjournal/clerk/view.clj    | 9 ++++++---
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/nextjournal/clerk/builder.clj b/src/nextjournal/clerk/builder.clj
index f79a1eab2..32e44a6da 100644
--- a/src/nextjournal/clerk/builder.clj
+++ b/src/nextjournal/clerk/builder.clj
@@ -411,7 +411,7 @@
                       :exclude-js? true
                       ;; test against cljs release `bb build:js`
                       :resource->url {"/js/viewer.js" "./build/viewer.js"}
-                      :index "notebooks/scratch.clj"})
+                      :index "notebooks/viewers/katex.clj"})
 
   (build-static-app! {:ssr? true
                       :exclude-js? true
diff --git a/src/nextjournal/clerk/view.clj b/src/nextjournal/clerk/view.clj
index 9cd55f543..f9d6dd2f1 100644
--- a/src/nextjournal/clerk/view.clj
+++ b/src/nextjournal/clerk/view.clj
@@ -8,14 +8,17 @@
   (:import (java.net URI)))
 
 (defn viewer-names [state]
-  (let [!state (atom #{})]
+  (let [!viewers (atom #{})]
     (w/postwalk (fn [v]
                   (if-let [viewer (v/get-safe v :nextjournal/viewer)]
-                    (do (swap! !state conj (:name viewer))
+                    (do (swap! !viewers conj (:name viewer))
                         v)
                     v))
                 state)
-    (assoc state :katex? (contains? @!state 'nextjournal.clerk.viewer/katex-viewer))))
+    (let [viewers @!viewers]
+      (assoc state :katex? (some viewers #{'nextjournal.clerk.viewer/katex-viewer
+                                           :nextjournal.markdown/formula
+                                           :nextjournal.markdown/block-formula})))))
 
 (defn doc->viewer
   ([doc] (doc->viewer {} doc))

From 7cc646a7aea0c19dd7e01f2081839cd3f5df2325 Mon Sep 17 00:00:00 2001
From: Martin Kavalar <martin@nextjournal.com>
Date: Tue, 2 Sep 2025 09:34:13 +0200
Subject: [PATCH 24/24] Move katex to render

---
 shadow-cljs.edn                               | 4 ++--
 src/nextjournal/clerk/{ => render}/katex.cljs | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)
 rename src/nextjournal/clerk/{ => render}/katex.cljs (71%)

diff --git a/shadow-cljs.edn b/shadow-cljs.edn
index 68cb9b074..425b2822c 100644
--- a/shadow-cljs.edn
+++ b/shadow-cljs.edn
@@ -9,9 +9,9 @@
                    :dev {:modules {:viewer {:entries [devtools]}}}
                    :modules {:viewer {:entries [nextjournal.clerk.sci-env
                                                 nextjournal.clerk.trim-image]}
-                             :katex {:entries [katex nextjournal.clerk.katex]
+                             :katex {:entries [katex nextjournal.clerk.render.katex]
                                      :depends-on #{:viewer}
-                                     :exports {renderToString nextjournal.clerk.katex/renderToString}}}
+                                     :exports {renderToString nextjournal.clerk.render.katex/renderToString}}}
                    :js-options {:output-feature-set :es8}
                    :build-hooks [(shadow.cljs.build-report/hook
                                   {:output-to "report.html" :print-table true})]}}}
diff --git a/src/nextjournal/clerk/katex.cljs b/src/nextjournal/clerk/render/katex.cljs
similarity index 71%
rename from src/nextjournal/clerk/katex.cljs
rename to src/nextjournal/clerk/render/katex.cljs
index c8710d288..962d90b2e 100644
--- a/src/nextjournal/clerk/katex.cljs
+++ b/src/nextjournal/clerk/render/katex.cljs
@@ -1,4 +1,4 @@
-(ns nextjournal.clerk.katex
+(ns nextjournal.clerk.render.katex
   (:require ["katex" :as katex]))
 
 (defn renderToString [s]