diff --git a/Readme.md b/Readme.md
index 19c7356..60569e7 100644
--- a/Readme.md
+++ b/Readme.md
@@ -603,8 +603,9 @@ decides where code runs, not the syntax.
 Compilation happens at macro-expansion time (via the same embedded
 [Squint](https://github.com/squint-cljs/squint) compiler that powers
 [client components](#client-components-web-components)) — runtime cost is
-string interpolation of spliced values only. Output is dependency-free
-JavaScript suitable for Datastar's sandboxed evaluator.
+string interpolation of spliced values only. Output calls Squint's core
+library through the `hyper_sc` global, which hyper serves at
+`/hyper/squint-core.js`.
 
 ### Actions inside expressions
 
@@ -2043,6 +2044,25 @@ inside segments.
 For self-hosted/air-gapped deploys, override the Squint runtime CDN URL
 with the `:squint-core-url` option on `create-handler`.
 
+### Tree shaking
+
+Pass `:tree-shake? true` to `create-handler` to serve only the Squint core
+functions that your `h/expr` expressions use, instead of all of
+`/hyper/squint-core.js` (28 KB brotli-compressed):
+
+```clojure
+(h/create-handler #'routes :tree-shake? true)
+```
+
+Add esbuild to `deps.edn`:
+
+```clojure
+org.babashka/esbuild {:mvn/version "0.1.1"}
+```
+
+Add `--enable-native-access=ALL-UNNAMED` to your JVM options for esbuild.
+Without esbuild on the classpath, `create-handler` throws.
+
 ### Editor indentation
 
 `defc`'s `render`/`event`/`mount`/`update`/`unmount` segments are
diff --git a/deps.edn b/deps.edn
index f4a2d0f..092fa67 100644
--- a/deps.edn
+++ b/deps.edn
@@ -36,26 +36,30 @@
   cheshire/cheshire                   {:mvn/version "6.1.0"}
 
   ;; Client-side component compilation (CLJS-dialect -> JS)
-  io.github.squint-cljs/squint        {:mvn/version "0.14.203"}
+  io.github.squint-cljs/squint        {:mvn/version "0.14.209"}
 
   ;; Logging
   com.taoensso/telemere               {:mvn/version "1.2.1"}}
 
  :aliases
- {:test  {:extra-paths ["test"]
-          :extra-deps  {org.clojure/test.check     {:mvn/version "1.1.3"}
-                        lambdaisland/kaocha        {:mvn/version "1.91.1392"}
-                        nubank/matcher-combinators {:mvn/version "3.10.0"}
-                        io.github.pfeodrippe/wally {:mvn/version "0.0.5"}}
-          :main-opts   ["-m" "kaocha.runner"]
-          :exec-fn     kaocha.runner/exec-fn
-          :exec-args   {:randomize? false
-                        :fail-fast? true}}
-  :dev   {:extra-deps {io.github.tonsky/clj-reload {:mvn/version "1.0.0"}}}
+ {:test       {:extra-paths ["test"]
+               :extra-deps  {org.clojure/test.check     {:mvn/version "1.1.3"}
+                             lambdaisland/kaocha        {:mvn/version "1.91.1392"}
+                             nubank/matcher-combinators {:mvn/version "3.10.0"}
+                             io.github.pfeodrippe/wally {:mvn/version "0.0.5"}}
+               :main-opts   ["-m" "kaocha.runner"]
+               :exec-fn     kaocha.runner/exec-fn
+               :exec-args   {:randomize? false
+                             :fail-fast? true}}
+  :dev        {:extra-deps {io.github.tonsky/clj-reload {:mvn/version "1.0.0"}}}
+
+  ;; Serves only the squint core functions that h/expr output uses.
+  :tree-shake {:extra-deps {org.babashka/esbuild {:mvn/version "0.1.1"}}
+               :jvm-opts   ["--enable-native-access=ALL-UNNAMED"]}
 
   ;; Build, install, deploy. See dev/build.clj.
   ;; Invoke with: clj -T:build <task>
-  :build {:deps       {io.github.clojure/tools.build {:git/tag "v0.10.7" :git/sha "573711e"}
-                       slipset/deps-deploy           {:mvn/version "0.2.3"}}
-          :paths      ["dev"]
-          :ns-default build}}}
+  :build      {:deps       {io.github.clojure/tools.build {:git/tag "v0.10.7" :git/sha "573711e"}
+                            slipset/deps-deploy           {:mvn/version "0.2.3"}}
+               :paths      ["dev"]
+               :ns-default build}}}
diff --git a/src/hyper/core.clj b/src/hyper/core.clj
index 8b70d62..a77cdfd 100644
--- a/src/hyper/core.clj
+++ b/src/hyper/core.clj
@@ -929,6 +929,8 @@
    - :squint-core-url   — Override of the squint core.js URL used by the client
                           components bundle (default: version-matched jsDelivr CDN).
                           Point at a self-hosted copy for offline/air-gapped deploys.
+   - :tree-shake?       - Serve only the squint core functions that h/expr output
+                          uses. Needs babashka.esbuild on the classpath.
    - :head              — Hiccup nodes appended to the HTML <head>, or (fn [req] ...) -> hiccup
    - :webkit-sse-shim?  — Inject a small client shim (into <head>, only for WebKit/Safari
                           user agents) that routes the GET render stream through a native
@@ -1003,7 +1005,7 @@
      (stop! app)"
   [routes & {:keys [app-state head static-resources static-dir watches
                     datastar-script base-path middleware render-middleware
-                    render-error squint-core-url render-guard
+                    render-error squint-core-url tree-shake? render-guard
                     max-file-size max-file-count upload-expires-in]
              :or   {app-state       (atom (state/init-state))
                     datastar-script server/default-datastar-script}
@@ -1017,7 +1019,8 @@
                                   :base-path         base-path
                                   :middleware        middleware
                                   :render-middleware render-middleware
-                                  :squint-core-url   squint-core-url}
+                                  :squint-core-url   squint-core-url
+                                  :tree-shake?       tree-shake?}
                            ;; Only forward when supplied so server defaults apply.
                            render-error (assoc :render-error render-error)
                            render-guard (assoc :render-guard render-guard)
diff --git a/src/hyper/expr.clj b/src/hyper/expr.clj
index 60f2549..3864db8 100644
--- a/src/hyper/expr.clj
+++ b/src/hyper/expr.clj
@@ -37,9 +37,8 @@
      Datastar actions (`(@post \"/x\")`), JS interop and operators.
 
    Compilation happens at macro-expansion time via Squint — runtime cost
-   is string interpolation of spliced values only.  Output is
-   dependency-free JavaScript for Datastar's sandboxed evaluator:
-   `and`/`or`/`not`/`str` etc. emit bare JS operators, never library calls.
+   is string interpolation of spliced values only.  Output calls squint
+   core through the `hyper_sc` global, which hyper serves.
 
    The transpiler core is ported, with gratitude, from Casey Link's
    datastar-expressions (https://github.com/outskirtslabs/datastar-expressions,
@@ -59,67 +58,7 @@
 ;; ---------------------------------------------------------------------------
 ;; Squint special-form overrides
 ;; ---------------------------------------------------------------------------
-;; Datastar expressions run in a sandboxed evaluator with no library
-;; runtime, so boolean/control/string forms must compile to bare JS
-;; operators rather than squint_core calls.  These compiler macros
-;; (squint's :macros option) replace the defaults.
-
-(defn- bool-expr [e]
-  (if (boolean? e)
-    e
-    (vary-meta e assoc :tag 'boolean)))
-
-(defn- expr-and
-  ([_ _] true)
-  ([_ _ x] x)
-  ([_ _ x & next]
-   (let [js (str/join " && " (repeat (inc (count next)) "(~{})"))]
-     (bool-expr (concat (list 'js* js) (cons x next))))))
-
-(defn- expr-or
-  ([_ _] nil)
-  ([_ _ x] x)
-  ([_ _ x & next]
-   (let [js (str/join " || " (repeat (inc (count next)) "(~{})"))]
-     (bool-expr (concat (list 'js* js) (cons x next))))))
-
-(defn- expr-not [_ _ x]
-  (bool-expr (concat (list 'js* "(!(~{}))") (list x))))
-
-(defn- expr-do
-  ([_ _] nil)
-  ([_ _ & exprs]
-   (let [js (str/join ", " (repeat (count exprs) "(~{})"))]
-     (concat (list 'js* js) exprs))))
-
-(defn- expr-if [_ _ test & body]
-  (list 'if (bool-expr test) (first body) (second body)))
-
-(defn- expr-when [_ _ test & body]
-  (list 'if (bool-expr test) (cons 'expr/do body)))
-
-(defn- expr-when-not [_ _ test & body]
-  (list 'if-not (bool-expr test) (cons 'expr/do body)))
-
-(defn- expr-eq
-  ([_ _ _x] true)
-  ([_ _ x y]
-   (bool-expr (concat (list 'js* "(~{}) === (~{})") (list x y))))
-  ([_ _ x y & more]
-   (let [args  (list* x y more)
-         pairs (partition 2 1 args)
-         js    (str/join " && " (repeat (count pairs) "((~{}) === (~{}))"))]
-     (bool-expr (concat (list 'js* js) (mapcat identity pairs))))))
-
-(defn- expr-str
-  ([_ _] "")
-  ([_ _ & exprs]
-   (let [js (str/join " + " (cons "''" (repeat (count exprs) "(~{})")))]
-     (concat (list 'js* js) exprs))))
-
-(defn- expr-println [_ _ & exprs]
-  (let [js (str/join "," (repeat (count exprs) "(~{})"))]
-    (concat (list 'js* (str "console.log(" js ")")) exprs)))
+;; Compiler macros (squint's :macros option) that replace the defaults.
 
 (defn- expr-raw
   ([_ _] (list 'js* ""))
@@ -127,55 +66,13 @@
    (let [js (str/join (repeat (count x) "~{}"))]
      (concat (list 'js* js) x))))
 
-(def ^:private macro-replacements
-  {'and      'expr/and
-   '&&       'expr/and
-   'or       'expr/or
-   '||       'expr/or
-   'if       'expr/if
-   'not      'expr/not
-   '=        'expr/=
-   'str      'expr/str
-   'println  'expr/println
-   'when     'expr/when
-   'when-not 'expr/when-not
-   'expr/raw 'expr/raw})
-
 (def ^:private compiler-macros
-  {'expr {'and      expr-and
-          'or       expr-or
-          'when     expr-when
-          'when-not expr-when-not
-          'do       expr-do
-          'if       expr-if
-          'not      expr-not
-          '=        expr-eq
-          'str      expr-str
-          'println  expr-println
-          'raw      expr-raw}})
+  {'expr {'raw expr-raw}})
 
 ;; ---------------------------------------------------------------------------
 ;; Pre-processing (form level)
 ;; ---------------------------------------------------------------------------
 
-(defn- process-not-equals
-  "(not= x y) -> (not (= x y)) to avoid a squint_core dependency."
-  [form]
-  (walk/postwalk
-    (fn [node]
-      (if (and (seq? node) (= 'not= (first node)))
-        (list 'not (cons '= (rest node)))
-        node))
-    form))
-
-(defn- process-macros [form]
-  (walk/postwalk
-    (fn [node]
-      (if (and (seq? node) (contains? macro-replacements (first node)))
-        (cons (get macro-replacements (first node)) (rest node))
-        node))
-    form))
-
 (defn- process-client-params
   "Replace client-param symbols ($value, $key, $form-data, … and any
    user-registered ones) with their client-side JS, so expr shares the
@@ -197,7 +94,7 @@
       form)))
 
 (defn- pre-process [form]
-  (-> form process-not-equals process-macros process-client-params))
+  (process-client-params form))
 
 ;; ---------------------------------------------------------------------------
 ;; Post-processing (compiled JS level)
@@ -208,13 +105,8 @@
    squint_core.deref(get)(...) — restore Datastar's @action syntax."
   [js]
   (-> js
-      (str/replace #"squint_core\.deref\(squint_core\.(get)\)\s*\(" "@$1(")
-      (str/replace #"squint_core\.deref\(([a-zA-Z_$][a-zA-Z0-9_$]*)\)\s*\(" "@$1(")))
-
-(defn- replace-truth
-  "squint_core.truth_(x) -> !!(x) — no library runtime in the sandbox."
-  [js]
-  (str/replace js #"squint_core\.truth_\((.*)\)" "!!($1)"))
+      (str/replace #"hyper_sc\.deref\(hyper_sc\.(get)\)\s*\(" "@$1(")
+      (str/replace #"hyper_sc\.deref\(([a-zA-Z_$][a-zA-Z0-9_$]*)\)\s*\(" "@$1(")))
 
 (defn- collect-kebab-signals
   "All $signal symbols containing dashes, as name strings."
@@ -341,6 +233,16 @@
 ;; Compilation
 ;; ---------------------------------------------------------------------------
 
+(defonce ^{:doc "Munged squint core names referenced by compiled expressions."}
+  core-vars*
+  (atom (sorted-set)))
+
+;; A future squint release adds the used core names to the compiler output, which replaces this regex.
+(defn- record-core-vars! [js]
+  (when-let [names (seq (map second (re-seq #"hyper_sc\.([A-Za-z_$][\w$]*)" js)))]
+    (swap! core-vars* into names))
+  js)
+
 (defn compile-form
   "Compile a single (boundary-inferred) form to a Datastar expression
    string.  Public for testing."
@@ -353,9 +255,10 @@
                                 :elide-exports true
                                 :top-level     false
                                 :context       :expr
+                                :core-alias    "hyper_sc"
                                 :macros        compiler-macros})
         replace-deref
-        replace-truth
+        record-core-vars!
         (restore-signal-casing processed)
         (str/replace #"\n" " ")
         str/trim
@@ -387,6 +290,16 @@
           template
           pairs))
 
+;; Datastar adds `return` after the last `;`, even one inside a nested function (datastar#1215).
+(defn- join-statements
+  "Returns jss, the compiled forms, joined with `;`.
+   Returns the last form through `__hyper_r` if any form contains a `;`."
+  [jss]
+  (if (some #(str/includes? % ";") jss)
+    (str (str/join (map #(str % "; ") (butlast jss)))
+         "var __hyper_r = (" (last jss) "); return __hyper_r;")
+    (str/join "; " jss)))
+
 ;; ---------------------------------------------------------------------------
 ;; The macro
 ;; ---------------------------------------------------------------------------
@@ -413,7 +326,7 @@
   (let [env-locals (set (keys &env))
         pairs*     (atom [])
         forms*     (mapv #(infer-boundary % env-locals pairs*) forms)
-        template   (str/join "; " (map compile-form forms*))
+        template   (join-statements (map compile-form forms*))
         pairs      @pairs*]
     (if (empty? pairs)
       template
diff --git a/src/hyper/expr/bundle.clj b/src/hyper/expr/bundle.clj
new file mode 100644
index 0000000..eeba564
--- /dev/null
+++ b/src/hyper/expr/bundle.clj
@@ -0,0 +1,43 @@
+(ns ^:no-doc hyper.expr.bundle
+  "Builds an ES module with the squint core functions that h/expr output uses.
+   Needs babashka.esbuild on the classpath."
+  (:require [babashka.esbuild :as esbuild]
+            [babashka.fs :as fs]
+            [clojure.java.io :as io]
+            [clojure.string :as str]
+            [hyper.brotli :as br]))
+
+(def ^:private core-dir
+  (delay
+    (let [dir (fs/create-temp-dir {:prefix "hyper-squint-core"})]
+      (with-open [in (io/input-stream (io/resource "squint/core.js"))]
+        (io/copy in (fs/file dir "core.js")))
+      dir)))
+
+(def ^:private last-build (atom nil))
+
+(defn- build [vars]
+  (let [entry (fs/file @core-dir "entry.js")]
+    (spit entry (str "export { " (str/join ", " (sort vars)) " } from './core.js';\n"))
+    (let [js (-> (esbuild/build {:entry-points [(str entry)]
+                                 :bundle       true
+                                 :format       :esm
+                                 :minify       true})
+                 :outputs first :contents)]
+      {:js js :br (br/compress js :quality 11)})))
+
+(defn core-js
+  "Returns a map with :js, minified JS that exports vars, and :br, the same JS brotli-compressed.
+   vars is a set of munged squint core names.
+   Keeps only the build for the last vars."
+  [vars]
+  (let [[built-vars result] @last-build]
+    (if (= vars built-vars)
+      result
+      (locking last-build
+        (let [[built-vars result] @last-build]
+          (if (= vars built-vars)
+            result
+            (let [result (build vars)]
+              (reset! last-build [vars result])
+              result)))))))
diff --git a/src/hyper/server.clj b/src/hyper/server.clj
index 587e74a..d113bb9 100644
--- a/src/hyper/server.clj
+++ b/src/hyper/server.clj
@@ -13,6 +13,7 @@
             [hyper.component.bundle :as component.bundle]
             [hyper.context :as context]
             [hyper.effects :as effects]
+            [hyper.expr :as expr]
             [hyper.lifecycle :as lifecycle]
             [hyper.reactive :as reactive]
             [hyper.render :as render]
@@ -145,6 +146,20 @@
                 :headers (:headers render-result)
                 :tab-id  tab-id})))))
 
+(def ^:private squint-core-sha
+  (delay
+    (.formatHex (java.util.HexFormat/of)
+                (.digest (java.security.MessageDigest/getInstance "SHA-256")
+                         (.getBytes ^String (slurp (io/resource "squint/core.js")) "UTF-8")))))
+
+(defn- squint-core-version
+  "Returns a version string for the squint core that /hyper/squint-core.js serves.
+   The version changes if the served JS changes."
+  [app-state*]
+  (if (:tree-shake? @app-state*)
+    (Integer/toHexString (hash [@squint-core-sha @expr/core-vars*]))
+    (subs @squint-core-sha 0 12)))
+
 (defn- handle-full-render
   "Perform a full page render and send the assembled SSE events (head update,
    body fragment, signal patches).  Sweeps stale actions/reactive components
@@ -175,6 +190,7 @@
         (let [head-event   (render/format-head-update title head-html)
               sig-attrs    (signal/format-signal-attrs declared-signals)
               div-attrs    (cond-> {:id "hyper-app"}
+                             (:tree-shake? @app-state*) (assoc :data-hyper-squint-version (squint-core-version app-state*))
                              url       (assoc :data-hyper-url url)
                              sig-attrs (merge sig-attrs))
               wrapped-html (c/html [:div div-attrs (c/raw body-html)])
@@ -834,16 +850,21 @@
     window.history.replaceState({title: document.title}, '', window.location.href);
     var observer = new MutationObserver(function(mutations) {
       for (var i = 0; i < mutations.length; i++) {
+        if (mutations[i].attributeName === 'data-hyper-squint-version') {
+          var version = appEl.getAttribute('data-hyper-squint-version');
+          if (window.hyper_squint_version && version && version !== window.hyper_squint_version) {
+            window.location.reload();
+          }
+        }
         if (mutations[i].attributeName === 'data-hyper-url') {
           var url = appEl.getAttribute('data-hyper-url');
           if (url && url !== window.location.pathname + window.location.search) {
             window.history.replaceState({title: document.title}, '', url);
           }
-          break;
         }
       }
     });
-    observer.observe(appEl, { attributes: true, attributeFilter: ['data-hyper-url'] });
+    observer.observe(appEl, { attributes: true, attributeFilter: ['data-hyper-url', 'data-hyper-squint-version'] });
   }
   window.addEventListener('pageshow', function(event) {
     var nav = performance.getEntriesByType && performance.getEntriesByType('navigation')[0];
@@ -878,7 +899,7 @@
    Shared by page-handler and not-found-handler so both emit identical document
    scaffolding, differing only in `status` and `fallback-title` (the <title>
    used when the result has no :title)."
-  [result {:keys [datastar-script open-when-hidden? base-path webkit-sse-shim?]
+  [result {:keys [datastar-script open-when-hidden? base-path webkit-sse-shim? core-version tree-shake?]
            :or   {open-when-hidden? true
                   base-path         ""
                   webkit-sse-shim?  true}}
@@ -887,6 +908,7 @@
         title                                                (or title fallback-title)
         sig-attrs                                            (signal/format-signal-attrs declared-signals)
         div-attrs                                            (cond-> {:id "hyper-app"}
+                                                               tree-shake? (assoc :data-hyper-squint-version core-version)
                                                                sig-attrs (merge sig-attrs))
         ;; WebKit/Safari fetch-streaming strand workaround: inject the
         ;; EventSource shim only for affected user agents, before the datastar
@@ -903,6 +925,10 @@
                                                                   [:meta {:name "viewport" :content "width=device-width, initial-scale=1"}]
                                                                   [:title title]
                                                                   webkit-shim
+                                                                  [:script {:type "module"}
+                                                                   (c/raw (str "import * as sc from '" base-path "/hyper/squint-core.js?v=" core-version "';\n"
+                                                                               "window.hyper_sc = sc;"
+                                                                               (when tree-shake? (str "\nwindow.hyper_squint_version = '" core-version "';"))))]
                                                                   datastar-script
                                                                   (when head-html (c/raw head-html))]
                                                                  [:body
@@ -943,7 +969,7 @@
           ;; Ring response passthrough (e.g. a 302 redirect)
           (if (:status result)
             result
-            (page-response result opts req tab-id 200 "Hyper App")))))))
+            (page-response result (assoc opts :core-version (squint-core-version app-state*) :tree-shake? (:tree-shake? @app-state*)) req tab-id 200 "Hyper App")))))))
 
 (defn- not-found-handler
   "Reitit default-handler for unmatched routes: renders the configured
@@ -969,7 +995,7 @@
         ;; Ring response passthrough (e.g. a redirect from render middleware)
         (if (:status result)
           result
-          (page-response result opts req tab-id 404 "Not Found"))))))
+          (page-response result (assoc opts :core-version (squint-core-version app-state*) :tree-shake? (:tree-shake? @app-state*)) req tab-id 404 "Not Found"))))))
 
 (defn- components-js-handler
   "Serve the assembled client-components ES module bundle.
@@ -1002,6 +1028,30 @@
        :headers {"Content-Type" "text/plain"}
        :body    "No components registered"})))
 
+(defn- squint-core-js-handler
+  "Returns a handler that serves squint's core.js from the classpath.
+   Serves only the functions h/expr output uses if tree-shake? is true, which needs babashka.esbuild.
+   Caches the response as immutable if its v query parameter is the current version."
+  [app-state* tree-shake?]
+  (let [js      (slurp (io/resource "squint/core.js"))
+        js-br   (delay (br/compress js :quality 11))
+        core-js (when tree-shake? (requiring-resolve 'hyper.expr.bundle/core-js))]
+    (fn [req]
+      (let [br?  (br/accepts-br? req)
+            body (cond
+                   core-js (let [{:keys [js br]} (core-js (set @expr/core-vars*))]
+                             (if br? br js))
+                   br?     @js-br
+                   :else   js)]
+        {:status  200
+         :headers (cond-> {"Content-Type"  "text/javascript; charset=utf-8"
+                           "Cache-Control" (if (= (get-in req [:query-params "v"])
+                                                  (squint-core-version app-state*))
+                                             "public, max-age=31536000, immutable"
+                                             "no-cache")}
+                    br? (assoc "Content-Encoding" "br"))
+         :body    body}))))
+
 (defn- -navigation-parameters
   "Coerces navigation parameters with the matched GET route's compiled validator."
   [match request]
@@ -1275,7 +1325,8 @@
                           [(str base-path "/hyper/actions") {:post (action-handler app-state*)}]
                           [(str base-path "/hyper/upload") {:post upload-route}]
                           [(str base-path "/hyper/navigate") {:post (navigate-handler app-state*)}]
-                          [(str base-path "/hyper/components.js") {:get (components-js-handler app-state*)}]]
+                          [(str base-path "/hyper/components.js") {:get (components-js-handler app-state*)}]
+                          [(str base-path "/hyper/squint-core.js") {:get (squint-core-js-handler app-state* (:tree-shake? opts))}]]
          ;; Store the routes source (Var or value) so title resolution can
          ;; always read the latest route metadata, even between router rebuilds.
          ;; Store global :watches so find-route-watches can prepend them to
@@ -1295,7 +1346,8 @@
                                 :disconnect-grace-ms disconnect-grace-ms
                                 :heartbeat-ms heartbeat-ms
                                 :open-when-hidden? (get opts :open-when-hidden? true)
-                                :squint-core-url (:squint-core-url opts))
+                                :squint-core-url (:squint-core-url opts)
+                                :tree-shake? (:tree-shake? opts))
          initial-routes  (if (var? routes) @routes routes)
          initial-handler (build-ring-handler initial-routes app-state* page-wrapper system-routes default-handler)
          handler         (if (var? routes)
diff --git a/test/hyper/core_test.clj b/test/hyper/core_test.clj
index ea5a620..d532252 100644
--- a/test/hyper/core_test.clj
+++ b/test/hyper/core_test.clj
@@ -501,7 +501,7 @@
                                    :hyper/app-state  app-state*}]
         (let [action-expr (str (hy/action {:when (hy/expr (= evt.key "Enter"))}
                                           (reset! (hy/tab-cursor :val) $value)))]
-          (is (.startsWith action-expr "(evt.key) === (\"Enter\") && "))
+          (is (.startsWith action-expr "(evt.key === \"Enter\") && "))
           (is (.contains action-expr "@post("))))))
 
   (testing ":when guard evaluating to a non-string throws"
diff --git a/test/hyper/e2e_test.clj b/test/hyper/e2e_test.clj
index f24322a..6f62762 100644
--- a/test/hyper/e2e_test.clj
+++ b/test/hyper/e2e_test.clj
@@ -9,6 +9,7 @@
             [clojure.test :refer [deftest is testing use-fixtures]]
             [hyper.core :as h]
             [hyper.effects :as effects]
+            [hyper.server]
             [hyper.state :as state]
             [wally.main :as w])
   (:import (com.microsoft.playwright Playwright BrowserType$LaunchOptions)))
@@ -289,6 +290,29 @@
      [:button#bump-btn {:data-on:click (h/action (swap! n* inc))} "bump"]
      [:button#commit-btn {:data-on:click (h/action (h/commit! w*))} "commit"]]))
 
+(def ^:private truthiness-rows [{:name "alice"} {:name "bob"}])
+
+(defn- expr-truthiness-get [_]
+  (let [selected* (h/signal :selected nil)]
+    [:div
+     [:h1 "Test Expr Truthiness"]
+     [:ul (for [[i row] (map-indexed vector truthiness-rows)]
+            [:li {:id (str "row-" (:name row)) :data-on:click (h/expr (reset! selected* i))} (:name row)])]
+     [:button#delete-btn
+      {:data-on:click (h/expr (when @selected*
+                                (h/action (reset! (h/tab-cursor :deleted)
+                                                  (:name (nth truthiness-rows @selected*))))))}
+      "Delete"]
+     [:span#deleted @(h/tab-cursor :deleted "none")]]))
+
+(defn- expr-nested-get [_]
+  (let [a* (h/signal :a false)
+        b* (h/signal :b 7)]
+    [:div
+     [:h1 "Test Expr Nested"]
+     [:span#when-let {:data-text (h/expr (when-let [x (or @a* @b*)] x))}]
+     [:span#re-find {:data-text (h/expr (let [s (or @a* "xa;by")] (re-find #"a;b" s)))}]]))
+
 (defn default-routes []
   [["/" {:name  :home
          :title "Home"
@@ -332,7 +356,15 @@
    ["/optimistic"
     {:name  :optimistic
      :title "Optimistic"
-     :get   #'optimistic-get}]])
+     :get   #'optimistic-get}]
+   ["/expr-truthiness"
+    {:name  :expr-truthiness
+     :title "Expr Truthiness"
+     :get   #'expr-truthiness-get}]
+   ["/expr-nested"
+    {:name  :expr-nested
+     :title "Expr Nested"
+     :get   #'expr-nested-get}]])
 
 (def ^:dynamic *test-routes* (default-routes))
 
@@ -352,7 +384,8 @@
 
 (defn start-test-server! []
   (reset! test-state* (atom (state/init-state)))
-  (let [handler (h/create-handler #'*test-routes* :app-state @test-state* :head #'test-head-var)]
+  (let [handler (h/create-handler #'*test-routes* :app-state @test-state* :head #'test-head-var
+                                  :tree-shake? (= "true" (System/getProperty "hyper.tree-shake")))]
     (reset! test-server (h/start! handler {:port test-port}))))
 
 (defn stop-test-server! []
@@ -1460,6 +1493,69 @@
         (finally
           (close-browser! browser-info))))))
 
+(deftest ^:e2e expr-truthiness-test
+  (let [browser-info (launch-browser)
+        ctx          (new-context browser-info)
+        page         (new-page ctx)]
+    (try
+      (w/with-page page
+        (w/navigate (str base-url "/expr-truthiness"))
+        (wait-for-sse)
+
+        (testing "signal value 1 runs the embedded action"
+          (w/click "#row-bob")
+          (w/click "#delete-btn")
+          (is (wait-for-text "#deleted" "bob")))
+
+        (testing "signal value 0 runs the embedded action"
+          (w/click "#row-alice")
+          (w/click "#delete-btn")
+          (is (wait-for-text "#deleted" "alice"))))
+      (finally
+        (close-browser! browser-info)))))
+
+(deftest ^:e2e squint-core-version-reload-test
+  (let [browser-info (launch-browser)
+        ctx          (new-context browser-info)
+        page         (new-page ctx)
+        tree-shake?  (:tree-shake? @@test-state*)]
+    (swap! @test-state* assoc :tree-shake? true)
+    (try
+      (w/with-page page
+        (w/navigate (str base-url "/counters"))
+        (wait-for-sse)
+        (wait-for-text "#counter-Session h2" "Session: 0")
+        (eval-js "window.__sameDocument = true")
+        (with-redefs-fn {#'hyper.server/squint-core-version (constantly "changed")}
+          (fn []
+            (click-counter-button "Session" ".inc")
+
+            (testing "a changed data-hyper-squint-version reloads the page"
+              (is (wait-for-pred #(nil? (eval-js "window.__sameDocument")) :timeout 10000)))
+
+            (testing "the reloaded page imports the changed squint core version"
+              (is (wait-for-pred #(= "changed" (eval-js "window.hyper_squint_version")) :timeout 10000))))))
+      (finally
+        (swap! @test-state* assoc :tree-shake? tree-shake?)
+        (close-browser! browser-info)))))
+
+(deftest ^:e2e expr-nested-test
+  (let [browser-info (launch-browser)
+        ctx          (new-context browser-info)
+        page         (new-page ctx)]
+    (try
+      (w/with-page page
+        (w/navigate (str base-url "/expr-nested"))
+        (wait-for-sse)
+
+        (testing "when-let over or renders the second operand"
+          (is (wait-for-text "#when-let" "7")))
+
+        (testing "re-find of #\"a;b\" inside let renders the match"
+          (is (wait-for-text "#re-find" "a;b"))))
+      (finally
+        (close-browser! browser-info)))))
+
 (deftest ^:e2e effects-combined-test
   (testing "multiple effects in one action all apply"
     (let [browser-info (launch-browser)
diff --git a/test/hyper/expr_test.clj b/test/hyper/expr_test.clj
index 2d75961..9247b46 100644
--- a/test/hyper/expr_test.clj
+++ b/test/hyper/expr_test.clj
@@ -35,35 +35,51 @@
 
 (deftest test-raw-datastar-style
   (testing "set! on $signals"
-    (is (= "$count = 0" (->expr (set! $count 0)))))
+    (is (= "($count = 0)" (->expr (set! $count 0)))))
 
   (testing "kebab-case signal names are preserved"
-    (is (= "$record-id = 5" (->expr (set! $record-id 5)))))
+    (is (= "($record-id = 5)" (->expr (set! $record-id 5)))))
 
   (testing "namespaced signals"
-    (is (= "$person.name = \"alice\"" (->expr (set! $person.name "alice")))))
+    (is (= "($person.name = \"alice\")" (->expr (set! $person.name "alice")))))
 
   (testing "actions"
     (is (= "@post(\"/update\")" (->expr (@post "/update"))))
     (is (= "@get(\"/poke\")" (->expr (@get "/poke")))))
 
   (testing "multiple statements join with ;"
-    (is (= "$a = 1; @get(\"/x\")" (->expr (set! $a 1) (@get "/x")))))
+    (is (= "($a = 1); @get(\"/x\")" (->expr (set! $a 1) (@get "/x")))))
+
+  (testing "a form with a ; returns its value through __hyper_r"
+    (let [out (->expr (when-let [x (or $a $b)] x))]
+      (is (str/starts-with? out "var __hyper_r = ((() => {"))
+      (is (str/ends-with? out "; return __hyper_r;"))))
+
+  (testing "earlier statements precede the __hyper_r variable"
+    (let [out (->expr (set! $z 1) (when-let [x (or $a $b)] x))]
+      (is (str/starts-with? out "($z = 1); var __hyper_r = ("))
+      (is (str/ends-with? out "; return __hyper_r;"))))
 
   (testing "evt and el pass through as client-side symbols"
-    (is (= "(evt.key) === (\"Enter\")" (->expr (= evt.key "Enter"))))
+    (is (= "(evt.key === \"Enter\")" (->expr (= evt.key "Enter"))))
     (is (str/includes? (->expr (.focus el)) "el.focus()"))))
 
 ;; ---------------------------------------------------------------------------
-;; Sandbox-safe operators (no squint_core in output, ever)
+;; Core references use the hyper_sc alias
 ;; ---------------------------------------------------------------------------
 
 (deftest test-sandbox-safe-output
-  (testing "boolean and equality forms compile to bare JS operators"
-    (is (= "(($a) === (1)) && (($b) || (evt.shiftKey))"
-           (->expr (and (= $a 1) (or $b evt.shiftKey)))))
-    (is (= "(!(($name) === (\"\")))" (->expr (not= $name ""))))
-    (is (= "'' + (\"n=\") + ($n)" (->expr (str "n=" $n)))))
+  (testing "= with a literal compiles to ==="
+    (let [out (->expr (and (= $a 1) (or $b evt.shiftKey)))]
+      (is (str/includes? out "($a === 1)"))
+      (is (str/includes? out "&&"))
+      (is (str/includes? out "evt.shiftKey"))))
+
+  (testing "not= compiles to hyper_sc._EQ_"
+    (is (= "!hyper_sc._EQ_($name, \"\")" (->expr (not= $name "")))))
+
+  (testing "str compiles to a template literal"
+    (is (= "`${\"n=\"}${$n??''}`" (->expr (str "n=" $n)))))
 
   (testing "when compiles to a ternary"
     (let [out (->expr (when $open (@post "/x")))]
@@ -91,27 +107,28 @@
 (deftest test-signal-atom-vocabulary
   (testing "swap! with not — the toggle idiom"
     (let [open?* (local-sig "open" false)]
-      (is (= "$_open = (!($_open))" (->expr (swap! open?* not))))))
+      (is (= "($_open = hyper_sc.not($_open))" (->expr (swap! open?* not))))))
 
   (testing "swap! with inc and with extra args"
     (let [n* (local-sig "n" 0)]
-      (is (= "$_n = ($_n + 1)" (->expr (swap! n* inc))))
-      (is (= "$_n = ($_n + 5)" (->expr (swap! n* + 5))))))
+      (is (= "($_n = ($_n + 1))" (->expr (swap! n* inc))))
+      (is (= "($_n = ($_n + 5))" (->expr (swap! n* + 5))))))
 
   (testing "reset! from a client-side value"
     (let [query* (sig "searchQuery")]
-      (is (= "$searchQuery = evt.target.value"
+      (is (= "($searchQuery = evt.target.value)"
              (->expr (reset! query* evt.target.value))))))
 
   (testing "deref reads as a signal reference"
     (let [name* (sig "userName")]
-      (is (= "(!(($userName) === (\"\")))" (->expr (not= @name* ""))))
+      (is (= "!hyper_sc._EQ_($userName, \"\")" (->expr (not= @name* ""))))
       (is (= "$userName" (->expr @name*)))))
 
   (testing "the full guard + assign + action composition"
     (let [query* (sig "q")]
-      (is (= (str "(((evt.key) === (\"Enter\")) ? "
-                  "(($q = evt.target.value), (@post(\"/search\"))) : (null))")
+      (is (= (str "var __hyper_r = ((((evt.key === \"Enter\")) ? "
+                  "((() => { $q = evt.target.value; return @post(\"/search\") })()) : (null))); "
+                  "return __hyper_r;")
              (->expr (when (= evt.key "Enter")
                        (reset! query* evt.target.value)
                        (@post "/search")))))))
@@ -129,22 +146,22 @@
   (testing "locals splice as JS literals"
     (let [factor 2
           label  "a'b"]
-      (is (= "$scaled = ($raw * 2)" (->expr (set! $scaled (* $raw factor)))))
-      (is (= "$label = 'a\\'b'" (->expr (set! $label label)))
+      (is (= "($scaled = ($raw * 2))" (->expr (set! $scaled (* $raw factor)))))
+      (is (= "($label = 'a\\'b')" (->expr (set! $label label)))
           "strings are escaped JS literals")))
 
   (testing "keyword-call forms evaluate as Clojure"
     (let [person {:id 1234 :name "alice"}]
-      (is (= "$person-id = 1234" (->expr (set! $person-id (:id person)))))
-      (is (= "$person-name = 'alice'" (->expr (set! $person-name (:name person)))))))
+      (is (= "($person-id = 1234)" (->expr (set! $person-id (:id person)))))
+      (is (= "($person-name = 'alice')" (->expr (set! $person-name (:name person)))))))
 
   (testing "explicit unquote still works as the escape hatch"
     (let [v 42]
-      (is (= "$x = 43" (->expr (set! $x ~(inc v)))))))
+      (is (= "($x = 43)" (->expr (set! $x ~(inc v)))))))
 
   (testing "collections splice as JS literals"
     (let [xs [1 2 3]]
-      (is (= "$items = [1, 2, 3]" (->expr (set! $items xs)))))))
+      (is (= "($items = [1, 2, 3])" (->expr (set! $items xs)))))))
 
 ;; ---------------------------------------------------------------------------
 ;; Compile-once semantics
@@ -168,9 +185,9 @@
 
 (deftest test-deref-signal-var
   (testing "deref of a top-level var holding a signal splices to a $ref"
-    (is (= "(!($_hyperConnected))"
+    (is (= "hyper_sc.not($_hyperConnected)"
            (->expr (not @signal/connected?*))))
-    (is (= "($_hyperConnection) === (\"reconnecting\")"
+    (is (= "($_hyperConnection === \"reconnecting\")"
            (->expr (= @signal/connection* :reconnecting)))))
 
   (testing "keyword and string tokens compile identically"
@@ -179,7 +196,7 @@
 
   (testing "deref of a non-signal var is left to the client (no splice)"
     (is (str/includes? (->expr (not @some-undefined-thing))
-                       "squint_core.deref"))))
+                       "hyper_sc.deref"))))
 
 ;; ---------------------------------------------------------------------------
 ;; DatastarExpr splicing — signals and actions ride one dispatch
@@ -217,7 +234,7 @@
       (rendering app-state*
                  (let [out (h/expr (when (= evt.key "Enter")
                                      (h/action (reset! (h/tab-cursor :q) 2))))]
-                   (is (str/includes? out "(evt.key) === (\"Enter\")"))
+                   (is (str/includes? out "evt.key === \"Enter\""))
                    (is (str/includes? out "@post('/hyper/actions?action-id=a_t_1')"))
                    (is (str/includes? out "?"))
                    (is (not (str/includes? out "action(")))))))
@@ -234,7 +251,7 @@
 
 (deftest test-client-params-in-expr
   (testing "client-param symbols expand to their client-side JS"
-    (is (= "(evt.key) === (\"Enter\")" (->expr (= $key "Enter"))))
+    (is (= "(evt.key === \"Enter\")" (->expr (= $key "Enter"))))
     (is (= "evt.target.checked" (->expr $checked)))
     (is (= "evt.detail" (->expr $detail)))
     (is (= "Object.fromEntries(new FormData(evt.target.closest('form')))"
@@ -246,7 +263,7 @@
              (->expr (reset! q* $value))))))
 
   (testing "non-param $signals still pass through untouched"
-    (is (= "$count = 0" (->expr (set! $count 0))))
+    (is (= "($count = 0)" (->expr (set! $count 0))))
     (let [name* (sig "userName")]
       (is (= "$userName" (->expr @name*)))))
 
@@ -255,5 +272,5 @@
       (rendering app-state*
                  (let [out (h/expr (when (= $key "Enter")
                                      (h/action (reset! (h/tab-cursor :q) $value))))]
-                   (is (str/includes? out "(evt.key) === (\"Enter\")"))
+                   (is (str/includes? out "evt.key === \"Enter\""))
                    (is (str/includes? out "hyper.encodeClientParams({value:evt.target.value})")))))))
diff --git a/test/hyper/server_test.clj b/test/hyper/server_test.clj
index 08d4f3f..dd7c67e 100644
--- a/test/hyper/server_test.clj
+++ b/test/hyper/server_test.clj
@@ -268,6 +268,27 @@
       (is (= 200 (:status response)))
       (is (= "static-ok\n" (slurp (:body response)))))))
 
+(deftest test-squint-core-js
+  (testing "repeated br requests return the identical compressed byte array"
+    (let [handler  (server/create-handler [["/" {:get (fn [_] [:div])}]] (atom (state/init-state)))
+          request  {:uri            "/hyper/squint-core.js"
+                    :request-method :get
+                    :headers        {"accept-encoding" "br"}}
+          response (handler request)]
+      (is (= "br" (get-in response [:headers "Content-Encoding"])))
+      (is (bytes? (:body response)))
+      (is (identical? (:body response) (:body (handler request)))))))
+
+(deftest test-squint-core-version
+  (testing "the versioned squint core URL of a page is cached as immutable"
+    (let [handler (server/create-handler [["/" {:get (fn [_] [:div])}]] (atom (state/init-state)))
+          page    (:body (handler {:uri "/" :request-method :get}))
+          v       (second (re-find #"squint-core\.js\?v=([0-9a-f]+)" page))]
+      (is (= "public, max-age=31536000, immutable"
+             (get-in (handler {:uri          "/hyper/squint-core.js" :request-method :get
+                               :query-string (str "v=" v)})
+                     [:headers "Cache-Control"]))))))
+
 (deftest test-open-when-hidden
   (testing "Default includes openWhenHidden: true in data-init"
     (let [app-state* (atom (state/init-state))
diff --git a/test/hyper/signal_test.clj b/test/hyper/signal_test.clj
index c29456e..8620d29 100644
--- a/test/hyper/signal_test.clj
+++ b/test/hyper/signal_test.clj
@@ -499,8 +499,8 @@
                                         "data-bind=\"sessionCols0Width\"")))
 
         (testing "expr treats it as a signal"
-          (is (= "$sessionCols0Width = 5" (->expr (reset! w* 5))))
-          (is (= "$sessionCols0Width = ($sessionCols0Width + 1)" (->expr (swap! w* inc))))
+          (is (= "($sessionCols0Width = 5)" (->expr (reset! w* 5))))
+          (is (= "($sessionCols0Width = ($sessionCols0Width + 1))" (->expr (swap! w* inc))))
           (is (= "$sessionCols0Width" (->expr @w*))))
 
         (testing "declares the signal with the current committed value"