feat(ui): serve an apple-touch-icon so iOS shows the logo on the home screen (#12917)

iOS ignores the SVG favicon and draws the first letter of the page title
when a page is saved to the home screen. Serve a 180x180 PNG made from
logo.png at /apple-touch-icon.png, link it from the React UI head, and
rewrite the link under a reverse-proxy prefix like the favicon link.

The logo is flattened on white because iOS fills transparency with black.

Assisted-by: Claude Code:claude-sonnet-5-5

Signed-off-by: Mauro Morales <contact@mauromorales.com>
Co-authored-by: Mauro Morales <contact@mauromorales.com>

core/http/app.go

@@ -389,6 +389,16 @@ func API(application *application.Application) (*echo.Echo, error) {
 		return c.Blob(http.StatusOK, "image/svg+xml", data)
 	})
 
+	// iOS draws the home-screen icon from an apple-touch-icon PNG and ignores
+	// the SVG favicon, so it falls back to the first letter of the page title.
+	e.GET("/apple-touch-icon.png", func(c echo.Context) error {
+		data, err := embedDirStatic.ReadFile("static/apple-touch-icon.png")
+		if err != nil {
+			return c.NoContent(http.StatusNotFound)
+		}
+		return c.Blob(http.StatusOK, "image/png", data)
+	})
+
 	// Static files - use fs.Sub to create a filesystem rooted at "static"
 	staticFS, err := fs.Sub(embedDirStatic, "static")
 	if err != nil {
@@ -671,6 +681,7 @@ func API(application *application.Application) (*echo.Echo, error) {
 					html := string(indexHTML)
 					html = strings.ReplaceAll(html, `="/assets/`, `="`+safePrefix+`assets/`)
 					html = strings.ReplaceAll(html, `="/favicon.svg"`, `="`+safePrefix+`favicon.svg"`)
+					html = strings.ReplaceAll(html, `="/apple-touch-icon.png"`, `="`+safePrefix+`apple-touch-icon.png"`)
 					indexHTML = []byte(html)
 				}
 				return c.HTMLBlob(http.StatusOK, indexHTML)

core/http/app_test.go

@@ -469,6 +469,7 @@ var _ = Describe("API test", func() {
 				Expect(string(body)).To(ContainSubstring(`<base href="https://example.org/myprefix/" />`), "body")
 				Expect(string(body)).ToNot(ContainSubstring(`="/assets/`), "asset URLs must include the prefix")
 				Expect(string(body)).ToNot(ContainSubstring(`="/favicon.svg"`), "favicon URL must include the prefix")
+				Expect(string(body)).ToNot(ContainSubstring(`="/apple-touch-icon.png"`), "touch icon URL must include the prefix")
 			})
 
 			// X-Forwarded-Prefix is attacker controllable on misconfigured

core/http/react-ui/index.html

@@ -5,6 +5,7 @@
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <title>LocalAI</title>
     <link rel="icon" type="image/svg+xml" href="/favicon.svg" />
+    <link rel="apple-touch-icon" href="/apple-touch-icon.png" />
     <script>
       // Set the theme before first paint, with the same rule as ThemeContext:
       // a stored choice wins, a fresh install opens dark.