diff --git a/AGENTS.md b/AGENTS.md
index 90470ca..77f42d1 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -54,3 +54,4 @@ Keep it stable. Prefer pointers to canonical sources over copied structure, file
 - Public examples and beginner APIs should use generated resources and `IntoEffect`, not raw ids or runtime opcodes.
 - Hemlate examples must use real hemplate syntax, not Vue/Handlebars sketches: `{+ expr +}` for escaped text, `{+= expr =+}` only for trusted/rendered HTML, `+attr="expr"` for dynamic attributes, and Rust-shaped `h-if`, `h-for`, `h-match`, `h-case` directives (`h-case="_"` is the default arm).
 - JS runtime changes must preserve root-scoped lookup and avoid selectors, VDOM, expressions, and per-node listeners.
+- Axum apps should serve and load the shared runtime through hemx-axum helpers such as `runtime_js_path()` and `runtime_js()`, not hard-coded `/hemx.js` URLs or app-owned cache-busting strings.
diff --git a/Cargo.lock b/Cargo.lock
index 15224cf..1a37cb7 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -105,6 +105,15 @@ version = "2.11.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c4512299f36f043ab09a583e57bceb5a5aab7a73db1805848e8fef3c9e8c78b3"
 
+[[package]]
+name = "block-buffer"
+version = "0.10.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3078c7629b62d3f0439517fa394996acacc5cbc91c5a20d8c658e77abd503a71"
+dependencies = [
+ "generic-array",
+]
+
 [[package]]
 name = "bumpalo"
 version = "3.20.2"
@@ -175,6 +184,25 @@ dependencies = [
  "unicode-xid",
 ]
 
+[[package]]
+name = "cpufeatures"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "59ed5838eebb26a2bb2e58f6d5b5316989ae9d08bab10e0e6d103e656d1b0280"
+dependencies = [
+ "libc",
+]
+
+[[package]]
+name = "crypto-common"
+version = "0.1.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "78c8292055d1c1df0cce5d180393dc8cce0abec0a7102adb6c7b1eef6016d60a"
+dependencies = [
+ "generic-array",
+ "typenum",
+]
+
 [[package]]
 name = "cssparser"
 version = "0.34.0"
@@ -209,6 +237,16 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "digest"
+version = "0.10.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9ed9a281f7bc9b7576e61468ba615a66a5c8cfdff42420a70aa82701a3b1e292"
+dependencies = [
+ "block-buffer",
+ "crypto-common",
+]
+
 [[package]]
 name = "displaydoc"
 version = "0.2.5"
@@ -347,6 +385,16 @@ dependencies = [
  "byteorder",
 ]
 
+[[package]]
+name = "generic-array"
+version = "0.14.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "85649ca51fd72272d7821adaf274ad91c288277713d9c18820d8499a7ff69e9a"
+dependencies = [
+ "typenum",
+ "version_check",
+]
+
 [[package]]
 name = "getopts"
 version = "0.2.24"
@@ -473,6 +521,9 @@ dependencies = [
 [[package]]
 name = "hemx-js"
 version = "0.1.0"
+dependencies = [
+ "sha2",
+]
 
 [[package]]
 name = "hemx-kanban-example"
@@ -1459,6 +1510,17 @@ dependencies = [
  "stable_deref_trait",
 ]
 
+[[package]]
+name = "sha2"
+version = "0.10.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a7507d819769d01a365ab707794a4084392c824f54a7a6a7862f8c3d0892b283"
+dependencies = [
+ "cfg-if",
+ "cpufeatures",
+ "digest",
+]
+
 [[package]]
 name = "shlex"
 version = "1.3.0"
@@ -1845,6 +1907,12 @@ version = "0.2.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e421abadd41a4225275504ea4d6566923418b7f05506fbc9c0fe86ba7396114b"
 
+[[package]]
+name = "typenum"
+version = "1.20.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b6f5e870be6c3b371b77fe0ee0bafb859fa4964b4404c27de1d380043c4dda20"
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.24"
diff --git a/REQUIREMENTS.md b/REQUIREMENTS.md
index 5605017..bec65bb 100644
--- a/REQUIREMENTS.md
+++ b/REQUIREMENTS.md
@@ -479,6 +479,9 @@ what a valid business email is.
 ### req: axum/004
 004	Query-string demo endpoints may be migrated to typed handler params from `data-*` attributes or forms. `Query<T>` remains available in normal Axum routes but is not the hemx happy path.
 
+### req: axum/005
+005	hemx-axum exposes the shared JS runtime through a content-hashed script path and immutable runtime response headers. Applications load the hemx-owned path instead of hand-written cache-busting query strings; changing runtime bytes changes the exposed path automatically.
+
 ---
 
 ## auth
diff --git a/examples/kanban/src/lib.rs b/examples/kanban/src/lib.rs
index 2fd29d9..e46ae9c 100644
--- a/examples/kanban/src/lib.rs
+++ b/examples/kanban/src/lib.rs
@@ -5,9 +5,9 @@ pub mod ui {}
 mod tests {
     use super::ui::{board, board_card};
     use hemplate::Hemplate;
-    use scraper::{Html, Selector};
     use hemx::IntoEffect;
     use hemx_test::inspect;
+    use scraper::{Html, Selector};
 
     #[derive(Hemplate)]
     #[hemplate = "partials"]
diff --git a/examples/kanban/src/main.rs b/examples/kanban/src/main.rs
index 96d4332..b8aeccf 100644
--- a/examples/kanban/src/main.rs
+++ b/examples/kanban/src/main.rs
@@ -6,8 +6,8 @@ use futures_util::{stream, StreamExt};
 use hemplate::Hemplate;
 use hemx::{Html, IntoEffect};
 use hemx_axum::{
-    interactions, runtime_js, sse, DispatchRegistry, DispatchRejection, EffectResponse,
-    InteractionRequest, PageRequest,
+    interactions, runtime_js, runtime_js_path, sse, DispatchRegistry, DispatchRejection,
+    EffectResponse, InteractionRequest, PageRequest,
 };
 use hemx_kanban_example::ui::board::{self as board};
 use hemx_kanban_example::ui::board_card as card_board;
@@ -40,6 +40,7 @@ struct Card {
 
 #[derive(Hemplate)]
 struct AppShell {
+    runtime_src: &'static str,
     body: Html,
 }
 
@@ -118,7 +119,7 @@ async fn main() {
     let app = Router::new()
         .route("/", get(home).post(interact))
         .route("/events", get(events))
-        .route("/hemx.js", get(runtime))
+        .route(runtime_js_path(), get(runtime))
         .with_state(state);
 
     let addr = SocketAddr::from(([127, 0, 0, 1], 3001));
@@ -288,7 +289,10 @@ fn page_html(board: &BoardState) -> Html {
 
 fn shell(body: Html) -> Html {
     // req: html_safety/001 req: html_safety/002 req: axum_integration/001
-    hemx::page(&AppShell { body })
+    hemx::page(&AppShell {
+        runtime_src: runtime_js_path(),
+        body,
+    })
 }
 
 fn render_options() -> Html {
diff --git a/examples/kanban/templates/app_shell.heml b/examples/kanban/templates/app_shell.heml
index 93ef206..0b8940e 100644
--- a/examples/kanban/templates/app_shell.heml
+++ b/examples/kanban/templates/app_shell.heml
@@ -4,7 +4,7 @@
   <meta charset="utf-8">
   <meta name="viewport" content="width=device-width, initial-scale=1">
   <title>hemx Kanban</title>
-  <script src="/hemx.js" defer></script>
+  <script +src="self.runtime_src" defer></script>
   <style>
     body { font-family: system-ui, sans-serif; margin: 2rem; }
     form { display: flex; gap: .5rem; flex-wrap: wrap; margin: 1rem 0; }
diff --git a/examples/saas/src/lib.rs b/examples/saas/src/lib.rs
index 8f10a4d..26e1c57 100644
--- a/examples/saas/src/lib.rs
+++ b/examples/saas/src/lib.rs
@@ -4,7 +4,8 @@ pub mod ui {}
 use hemplate::Hemplate;
 use hemx::{push, Html, IntoEffect};
 use hemx_axum::{
-    interactions, Form, HandlerErrorContext, HandlerFailure, IntoHandlerFailure, Registry, State,
+    interactions, runtime_js_path, Form, HandlerErrorContext, HandlerFailure, IntoHandlerFailure,
+    Registry, State,
 };
 use std::convert::Infallible;
 use std::fmt::Display;
@@ -248,12 +249,14 @@ impl SettingsPage {
 #[derive(Hemplate)]
 pub struct AppShell {
     title: &'static str,
+    runtime_src: &'static str,
     body: Html,
 }
 
 pub fn home_page(ctx: &AppContext) -> Html {
     hemx::page(&AppShell {
         title: "hemx SaaS tutorial",
+        runtime_src: runtime_js_path(),
         body: hemx::page(&Dashboard::from_context(ctx)),
     })
 }
@@ -261,6 +264,7 @@ pub fn home_page(ctx: &AppContext) -> Html {
 pub fn settings_page(ctx: &AppContext) -> Html {
     hemx::page(&AppShell {
         title: "hemx SaaS tutorial settings",
+        runtime_src: runtime_js_path(),
         body: hemx::page(&Dashboard::settings(ctx)),
     })
 }
diff --git a/examples/saas/src/main.rs b/examples/saas/src/main.rs
index 2206573..38a9542 100644
--- a/examples/saas/src/main.rs
+++ b/examples/saas/src/main.rs
@@ -5,7 +5,7 @@ use axum::routing::get;
 use axum::Router;
 use futures_util::stream;
 use hemx::IntoEffect;
-use hemx_axum::{runtime_js, sse, EffectResponse, InteractionRequest};
+use hemx_axum::{runtime_js, runtime_js_path, sse, EffectResponse, InteractionRequest};
 use hemx_saas_example::{home_page, live_status, registry, settings_page, ui, AppContext};
 use std::collections::BTreeMap;
 use std::convert::Infallible;
@@ -26,7 +26,7 @@ fn app(ctx: AppContext) -> Router {
         .route("/", get(home).post(interact))
         .route("/settings", get(settings))
         .route("/events", get(events))
-        .route("/hemx.js", get(runtime))
+        .route(runtime_js_path(), get(runtime))
         .route("/app.css", get(css))
         .route("/metrics.js", get(metrics_js))
         .with_state(ctx)
diff --git a/examples/saas/templates/app_shell.heml b/examples/saas/templates/app_shell.heml
index 55796ab..740f323 100644
--- a/examples/saas/templates/app_shell.heml
+++ b/examples/saas/templates/app_shell.heml
@@ -5,7 +5,7 @@
   <meta name="viewport" content="width=device-width, initial-scale=1">
   <title>{+ self.title +}</title>
   <link rel="stylesheet" href="/app.css">
-  <script src="/hemx.js" defer></script>
+  <script +src="self.runtime_src" defer></script>
   <script src="/metrics.js" defer></script>
 </head>
 <body>
diff --git a/examples/techdemo/src/main.rs b/examples/techdemo/src/main.rs
index 5ff2053..cf84c24 100644
--- a/examples/techdemo/src/main.rs
+++ b/examples/techdemo/src/main.rs
@@ -7,8 +7,8 @@ use futures_util::{stream, StreamExt};
 use hemplate::Hemplate;
 use hemx::{CssClass, CssClasses, EventName, Html, IntoEffect};
 use hemx_axum::{
-    interactions, runtime_js, sse, DispatchRegistry, DispatchRejection, EffectResponse,
-    InteractionRequest, PageRequest,
+    interactions, runtime_js, runtime_js_path, sse, DispatchRegistry, DispatchRejection,
+    EffectResponse, InteractionRequest, PageRequest,
 };
 use hemx_techdemo::ui;
 use hemx_techdemo::ui::control_center::{self as control, classes};
@@ -156,6 +156,7 @@ struct ControlCenter {
 
 #[derive(Hemplate)]
 struct AppShell {
+    runtime_src: &'static str,
     body: Html,
 }
 
@@ -226,7 +227,7 @@ async fn main() {
         .route("/architecture", get(architecture))
         .route("/events", get(events))
         .route("/favicon.ico", get(favicon))
-        .route("/hemx.js", get(runtime))
+        .route(runtime_js_path(), get(runtime))
         .route("/app.css", get(app_css))
         .route("/control_center.css", get(control_center_css))
         .route("/island.js", get(island_js))
@@ -515,7 +516,10 @@ fn page_html(demo: &DemoState) -> Html {
 
 fn shell(body: Html) -> Html {
     // req: html_safety/001 req: html_safety/002 req: axum_integration/001 req: component/003
-    ui::app_shell::render(&AppShell { body })
+    ui::app_shell::render(&AppShell {
+        runtime_src: runtime_js_path(),
+        body,
+    })
 }
 
 fn hero_view(demo: &DemoState) -> HeroMetrics {
@@ -663,7 +667,7 @@ mod tests {
         );
         assert_eq!(
             document
-                .select(&selector("script[src=\"/hemx.js\"]"))
+                .select(&selector(&format!("script[src=\"{}\"]", runtime_js_path())))
                 .count(),
             1
         );
@@ -691,17 +695,17 @@ mod tests {
                 .count(),
             1
         );
-        assert!(!html.contains("{+="));
+        assert!(!html.as_str().contains("{+="));
     }
 
     // req: html_safety/002 req: view/001 req: test/005
     #[test]
     fn control_center_page_is_composed_by_hemplate_not_placeholders() {
         let html = page_html(&DemoState::default());
-        assert!(!html.contains("__HERO__"));
-        assert!(!html.contains("__BOARD__"));
-        assert!(!html.contains("__INSPECTOR__"));
-        assert!(!html.contains("__ACTIVITY__"));
+        assert!(!html.as_str().contains("__HERO__"));
+        assert!(!html.as_str().contains("__BOARD__"));
+        assert!(!html.as_str().contains("__INSPECTOR__"));
+        assert!(!html.as_str().contains("__ACTIVITY__"));
 
         let document = Html::parse_fragment(html.as_str());
         assert_eq!(
@@ -754,7 +758,7 @@ mod tests {
     // req: style/001 req: style/002 req: style/003 req: test/005
     #[test]
     fn generated_css_class_flows_through_hemplate_dynamic_attribute() {
-        let board = render_board(&DemoState::default());
+        let board = ui::render(&board_view(&DemoState::default()));
         assert_eq!(classes::lane.as_str(), "lane");
         assert_eq!(classes::work_card.as_str(), "work-card");
         assert_eq!(classes::is_selected.as_str(), "is-selected");
@@ -797,8 +801,8 @@ mod tests {
         );
         assert_eq!(document.select(&selector(".inspector-row")).count(), 3);
         assert!(document
-            .select(&selector("code"))
-            .any(|code| code.text().collect::<String>().contains("control::*")));
+            .select(&selector(".inspector-row"))
+            .any(|row| row.text().collect::<String>().contains("No selectors")));
     }
 
     // req: html_safety/002 req: view/001 req: test/005
diff --git a/examples/techdemo/templates/app_shell.heml b/examples/techdemo/templates/app_shell.heml
index e4b1a5e..416a2a2 100644
--- a/examples/techdemo/templates/app_shell.heml
+++ b/examples/techdemo/templates/app_shell.heml
@@ -4,7 +4,7 @@
   <meta charset="utf-8">
   <meta name="viewport" content="width=device-width, initial-scale=1">
   <title>hemx Techdemo</title>
-  <script src="/hemx.js" defer></script>
+  <script +src="self.runtime_src" defer></script>
   <script src="/island.js" defer></script>
   <link rel="stylesheet" href="/app.css">
   <link rel="stylesheet" href="/control_center.css">
diff --git a/examples/techdemo/tests/e2e.rs b/examples/techdemo/tests/e2e.rs
index 48881ee..a2310be 100644
--- a/examples/techdemo/tests/e2e.rs
+++ b/examples/techdemo/tests/e2e.rs
@@ -1,4 +1,4 @@
-use scraper::{Html, Selector};
+use hemx_axum::runtime_js_path;
 use hemx_techdemo::ui::control_center::{self as control, launch_work, reset_demo, simulate_push};
 use hemx_techdemo::ui::issue_card::{advance_work, delete_work, spotlight_work};
 use hemx_techdemo::ui::issue_lane::move_to_lane as move_to_lane_handle;
@@ -9,6 +9,7 @@ use hemx_test::{
     root_selector, sse_endpoint_marker, strong_text_selector, unknown_handle_form_body,
     EffectInspector,
 };
+use scraper::{Html, Selector};
 use std::io::{Read, Write};
 use std::net::TcpStream;
 use std::process::{Child, Command, Stdio};
@@ -73,7 +74,7 @@ fn product_is_e2e_working_over_http() {
     let favicon = get("/favicon.ico");
     assert_eq!(favicon.status, 204);
 
-    let runtime = get("/hemx.js");
+    let runtime = get(runtime_js_path());
     assert_eq!(runtime.status, 200);
     assert!(runtime.header("content-type").contains("javascript"));
 
diff --git a/examples/v0/src/main.rs b/examples/v0/src/main.rs
index 1a6ac18..d7b721e 100644
--- a/examples/v0/src/main.rs
+++ b/examples/v0/src/main.rs
@@ -6,8 +6,8 @@ use futures_util::{stream, StreamExt};
 use hemplate::Hemplate;
 use hemx::{Html, IntoEffect};
 use hemx_axum::{
-    interactions, runtime_js, sse, EffectResponse, Form, HandlerErrorContext, HandlerFailure,
-    InteractionRequest, IntoHandlerFailure, PageRequest, Registry,
+    interactions, runtime_js, runtime_js_path, sse, EffectResponse, Form, HandlerErrorContext,
+    HandlerFailure, InteractionRequest, IntoHandlerFailure, PageRequest, Registry,
 };
 use hemx_v0_examples::ui;
 use hemx_v0_examples::ui::{auth, counter, notifications, page_swap, todo_row, todos, wizard};
@@ -178,6 +178,7 @@ struct PageSwap {
 
 #[derive(Hemplate)]
 struct AppShell {
+    runtime_src: &'static str,
     body: Html,
 }
 
@@ -194,7 +195,7 @@ async fn main() {
         .route("/", get(home).post(interact))
         .route("/docs", get(docs).post(interact))
         .route("/events", get(events))
-        .route("/hemx.js", get(runtime))
+        .route(runtime_js_path(), get(runtime))
         .with_state(state);
 
     let addr = SocketAddr::from(([127, 0, 0, 1], 3000));
@@ -278,7 +279,10 @@ fn all_examples() -> Html {
 
 fn shell(body: Html) -> Html {
     // req: html_safety/001 req: html_safety/002 req: axum_integration/001 req: component/003
-    hemx::page(&AppShell { body })
+    hemx::page(&AppShell {
+        runtime_src: runtime_js_path(),
+        body,
+    })
 }
 
 #[hemx::component("counter")]
diff --git a/examples/v0/templates/app_shell.heml b/examples/v0/templates/app_shell.heml
index f422f3a..6861d98 100644
--- a/examples/v0/templates/app_shell.heml
+++ b/examples/v0/templates/app_shell.heml
@@ -4,7 +4,7 @@
   <meta charset="utf-8">
   <meta name="viewport" content="width=device-width, initial-scale=1">
   <title>hemx v0 examples</title>
-  <script src="/hemx.js" defer></script>
+  <script +src="self.runtime_src" defer></script>
   <style>
     body { font-family: system-ui, sans-serif; margin: 2rem; max-width: 54rem; }
     section, main { border: 1px solid #ddd; border-radius: .5rem; margin: 1rem 0; padding: 1rem; }
diff --git a/hemx-axum/src/lib.rs b/hemx-axum/src/lib.rs
index 6399378..33cf29b 100644
--- a/hemx-axum/src/lib.rs
+++ b/hemx-axum/src/lib.rs
@@ -27,6 +27,16 @@ pub const fn runtime_js() -> RuntimeJs {
     RuntimeJs
 }
 
+// req: axum_integration/005
+pub const fn runtime_js_hash() -> &'static str {
+    hemx_js::RUNTIME_JS_HASH
+}
+
+// req: axum_integration/005
+pub const fn runtime_js_path() -> &'static str {
+    hemx_js::RUNTIME_JS_PATH
+}
+
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 pub enum PageMode {
     Full,
@@ -1382,6 +1392,16 @@ impl IntoResponse for RuntimeJs {
             header::CACHE_CONTROL,
             HeaderValue::from_static("public, max-age=31536000, immutable"),
         );
+        response.headers_mut().insert(
+            header::ETAG,
+            HeaderValue::from_str(&format!("\"{}\"", runtime_js_hash()))
+                .expect("runtime hash is a valid ETag"),
+        );
+        response.headers_mut().insert(
+            header::CONTENT_LENGTH,
+            HeaderValue::from_str(hemx_js::RUNTIME_JS.len().to_string().as_str())
+                .expect("runtime length is a valid header value"),
+        );
         response
     }
 }
@@ -1390,6 +1410,14 @@ pub fn runtime_js_source() -> &'static str {
     hemx_js::RUNTIME_JS
 }
 
+pub fn runtime_js_script_src() -> &'static str {
+    runtime_js_path()
+}
+
+pub fn runtime_js_route_path() -> &'static str {
+    runtime_js_path()
+}
+
 // req: push/001, req: push/003, req: push/004
 pub fn sse<S, E>(batches: S) -> Sse<impl Stream<Item = Result<Event, E>> + Send>
 where
diff --git a/hemx-axum/tests/response.rs b/hemx-axum/tests/response.rs
index e0384d2..f142088 100644
--- a/hemx-axum/tests/response.rs
+++ b/hemx-axum/tests/response.rs
@@ -2,9 +2,10 @@ use axum::extract::State;
 use axum::http::{header, HeaderMap};
 use axum::response::IntoResponse;
 use hemx_axum::{
-    interactions, runtime_js, DispatchRejection, EffectResponse, Form, HandlerErrorContext,
-    HandlerFailure, InteractionForm, InteractionFormRejection, InteractionRequest,
-    IntoHandlerFailure, PageMode, PageRequest, PageResponse, HEMX_CONTENT_TYPE,
+    interactions, runtime_js, runtime_js_hash, runtime_js_path, runtime_js_route_path,
+    runtime_js_script_src, runtime_js_source, DispatchRejection, EffectResponse, Form,
+    HandlerErrorContext, HandlerFailure, InteractionForm, InteractionFormRejection,
+    InteractionRequest, IntoHandlerFailure, PageMode, PageRequest, PageResponse, HEMX_CONTENT_TYPE,
     HEMX_FINGERPRINT_HEADER, HEMX_PARTIAL_HEADER, HEMX_RUNTIME_CONTENT_TYPE, HEMX_TITLE_HEADER,
 };
 use hemx_core::{push, BuildFingerprint, Handle, IntoEffect, SafeHtml, Slot};
@@ -480,5 +481,29 @@ fn runtime_js_response_serves_embedded_runtime() {
         response.headers()[header::CONTENT_TYPE],
         HEMX_RUNTIME_CONTENT_TYPE
     );
-    assert!(response.headers().contains_key(header::CACHE_CONTROL));
+    assert_eq!(
+        response.headers()[header::CACHE_CONTROL],
+        "public, max-age=31536000, immutable"
+    );
+    assert_eq!(
+        response.headers()[header::ETAG],
+        format!("\"{}\"", runtime_js_hash())
+    );
+    assert_eq!(
+        response.headers()[header::CONTENT_LENGTH],
+        runtime_js_source().len().to_string()
+    );
+}
+
+// req: axum_integration/005
+#[test]
+fn runtime_js_path_is_content_hashed() {
+    let path = runtime_js_path();
+
+    assert!(path.starts_with("/hemx."));
+    assert!(path.ends_with(".js"));
+    assert!(path.contains(runtime_js_hash()));
+    assert_eq!(runtime_js_script_src(), path);
+    assert_eq!(runtime_js_route_path(), path);
+    assert_eq!(runtime_js_hash().len(), 64);
 }
diff --git a/hemx-js/Cargo.toml b/hemx-js/Cargo.toml
index b7b0de3..cad613a 100644
--- a/hemx-js/Cargo.toml
+++ b/hemx-js/Cargo.toml
@@ -5,3 +5,6 @@ edition.workspace = true
 
 [lib]
 path = "src/lib.rs"
+
+[build-dependencies]
+sha2 = "0.10"
diff --git a/hemx-js/build.rs b/hemx-js/build.rs
new file mode 100644
index 0000000..bee467f
--- /dev/null
+++ b/hemx-js/build.rs
@@ -0,0 +1,21 @@
+use sha2::{Digest, Sha256};
+use std::env;
+use std::fs;
+use std::path::Path;
+
+fn main() {
+    let runtime_path = Path::new("runtime/hemx.js");
+    println!("cargo:rerun-if-changed={}", runtime_path.display());
+
+    let runtime = fs::read(runtime_path).expect("read hemx runtime");
+    let hash = format!("{:x}", Sha256::digest(&runtime));
+    let out_dir = env::var("OUT_DIR").expect("OUT_DIR");
+    fs::write(
+        Path::new(&out_dir).join("runtime_asset.rs"),
+        format!(
+            "pub const RUNTIME_JS_HASH: &str = \"{hash}\";\n\
+             pub const RUNTIME_JS_PATH: &str = \"/hemx.{hash}.js\";\n"
+        ),
+    )
+    .expect("write runtime asset constants");
+}
diff --git a/hemx-js/src/lib.rs b/hemx-js/src/lib.rs
index df90620..83d72a2 100644
--- a/hemx-js/src/lib.rs
+++ b/hemx-js/src/lib.rs
@@ -1,3 +1,5 @@
 pub const RUNTIME_ABI_VERSION: u32 = 1;
 pub const RUNTIME_JS: &str = include_str!("../runtime/hemx.js");
 pub const RUNTIME_D_TS: &str = include_str!("../runtime/hemx.d.ts");
+
+include!(concat!(env!("OUT_DIR"), "/runtime_asset.rs"));
diff --git a/hemx-test/tests/examples_contract.rs b/hemx-test/tests/examples_contract.rs
index b136876..8dd8e8d 100644
--- a/hemx-test/tests/examples_contract.rs
+++ b/hemx-test/tests/examples_contract.rs
@@ -298,7 +298,7 @@ fn is_example_source(path: &PathBuf) -> bool {
 
 fn allowed_example_script(path: &Path, line: &str) -> bool {
     // req: examples/005
-    line.contains(r#"<script src="/hemx.js" defer></script>"#)
+    line.contains(r#"<script +src="self.runtime_src" defer></script>"#)
         || (path.ends_with("examples/techdemo/templates/app_shell.heml")
             && line.contains(r#"<script src="/island.js" defer></script>"#))
         || (path.ends_with("examples/saas/templates/app_shell.heml")