fix(examples): mount www/ in Core-mode apps

examples/01-hello/README.md

@@ -37,7 +37,7 @@ never tears the SVG down and re-mounts it.
 ```
 examples/01-hello/
 ├── app.py            # Express: set_react_page() + 2 reactive_output outputs
-├── app-core.py       # Core: page_react_html() + App(app_ui, server), same outputs
+├── app-core.py       # Core: page_react_html() + App(..., static_assets=), same outputs
 ├── app.R             # R: page_react_html() + reactive_output, same outputs
 ├── faithful.py       # Old Faithful waiting times + a stdlib-only binner (Python)
 ├── faithful.csv      # base R's `faithful` dataset, exported for the Python servers
@@ -56,6 +56,11 @@ return `NULL` until the client's first `bins` message arrives (Python raises a
 silent exception instead), and wrap the histogram vectors in `I()` so a
 single-bin result still serializes as a JSON array rather than a scalar.
 
+`app-core.py` passes `static_assets={"/": .../www}` to `App()`. Shiny Express
+(`app.py`) and R's `runApp()` (`app.R`) both mount the app directory's `www/`
+automatically; Core's `App()` does not, so without it `index.html` loads and
+then 404s on `app.js` and `main.css`.
+
 ## Bridge primitives used
 
 - `from shinyreact import reactive_output, set_react_page` (Express server, `app.py`) / `page_react_html` (Core server, `app-core.py`); `library(shinyreact)` with `page_react_html()` + `reactive_output()` in `app.R`

examples/01-hello/app-core.py

@@ -1,3 +1,5 @@
+from pathlib import Path
+
 from faithful import histogram, waiting
 from shiny import App, Inputs, Outputs, Session
 from shinyreact import page_react_html, reactive_output
@@ -16,4 +18,7 @@ def dist_caption():
         return f"{len(waiting)} eruptions in {n} bin{'' if n == 1 else 's'}"
 
 
-app = App(app_ui, server)
+# Core apps must mount www/ themselves. Shiny Express auto-serves the app
+# directory's www/ at "/", but App() does not — without this, index.html loads
+# and then 404s on app.js and main.css.
+app = App(app_ui, server, static_assets={"/": Path(__file__).parent / "www"})

examples/10-bookmarking/app.py

@@ -1,3 +1,5 @@
+from pathlib import Path
+
 import shinyreact
 from shiny import App, Inputs, Outputs, Session, reactive
 
@@ -21,4 +23,11 @@ async def _on_bookmark_click() -> None:
         await session.bookmark()
 
 
-app = App(app_ui, server, bookmark_store="url")
+# Core apps must mount www/ themselves — App() has no equivalent of Shiny
+# Express's automatic www/ static mount.
+app = App(
+    app_ui,
+    server,
+    static_assets={"/": Path(__file__).parent / "www"},
+    bookmark_store="url",
+)

pkg-py/README.md

@@ -40,13 +40,20 @@ def greeting():
 
 Pair with a `www/index.html` that loads your React client (no-build `app.js` or a built bundle from `src/ui.tsx`). See the [examples catalog](../examples/README.md) for file layouts and dev workflows, from no-build to Vite + HMR.
 
-In Core mode, use `page_react_html()`:
+In Core mode, use `page_react_html()`. Core apps must also mount `www/`
+themselves — Shiny Express does this automatically, `App()` does not, and
+without it the page loads and then 404s on its own scripts and stylesheets:
 
 ```python
+from pathlib import Path
 from shiny import App
 import shinyreact
 
-app = App(shinyreact.page_react_html("www/index.html"), server)
+app = App(
+    shinyreact.page_react_html("www/index.html"),
+    server,
+    static_assets={"/": Path(__file__).parent / "www"},
+)
 ```
 
 ### Sending messages to React components

pkg-py/src/shinyreact/_page.py

@@ -236,6 +236,27 @@ def page_react_html(path: str | Path = "www/index.html") -> TagList:
     Unlike :func:`set_react_page`, this does not auto-discover dependencies
     from traditional Shiny renderers — it only attaches the shinyreact bundle.
 
+    Serving the client's files
+    --------------------------
+    This function only reads ``index.html``; it does not serve the sibling
+    files that ``index.html`` references. Shiny Express mounts the app
+    directory's ``www/`` at ``/`` automatically, but :class:`shiny.App` does
+    not, so a Core app must do it explicitly — otherwise the page loads and
+    then 404s on its own scripts and stylesheets::
+
+        from pathlib import Path
+        from shiny import App
+        from shinyreact import page_react_html
+
+        app = App(
+            page_react_html(),
+            server,
+            static_assets={"/": Path(__file__).parent / "www"},
+        )
+
+    (R's ``shiny::runApp()`` serves ``www/`` next to ``app.R`` automatically,
+    so the R counterpart needs no equivalent.)
+
     Args:
         path: Path to the HTML file. Absolute paths are used verbatim;
             relative paths resolve against the caller module's directory, or