refactor: simplify Datastar configuration API

Flatten DatastarConfig struct into Options (DatastarContent, DatastarPath)
and replace datastarHandlerRegistered bool with sync.Once for thread safety.

configuration.go

@@ -37,4 +37,12 @@ type Options struct {
 	// with scs LoadAndSave middleware. Configure the session manager before
 	// passing it (lifetime, cookie settings, store, etc).
 	SessionManager *scs.SessionManager
+
+	// DatastarContent is the Datastar.js script content.
+	// If nil, the embedded default is used.
+	DatastarContent []byte
+
+	// DatastarPath is the URL path where the script is served.
+	// Defaults to "/_datastar.js" if empty.
+	DatastarPath string
 }

context.go

@@ -318,6 +318,37 @@ func (c *Context) ExecScript(s string) {
 	c.sendPatch(patch{patchTypeScript, s})
 }
 
+// Redirect navigates the browser to the given URL.
+// This triggers a full page navigation - the current context will be disposed
+// and a new context created at the destination URL.
+func (c *Context) Redirect(url string) {
+	if url == "" {
+		c.app.logWarn(c, "redirect failed: empty url")
+		return
+	}
+	c.sendPatch(patch{patchTypeRedirect, url})
+}
+
+// Redirectf navigates the browser to a URL constructed from the format string and arguments.
+func (c *Context) Redirectf(format string, a ...any) {
+	c.Redirect(fmt.Sprintf(format, a...))
+}
+
+// ReplaceURL updates the browser's URL and history without triggering navigation.
+// Useful for updating query params or path to reflect UI state changes.
+func (c *Context) ReplaceURL(url string) {
+	if url == "" {
+		c.app.logWarn(c, "replace url failed: empty url")
+		return
+	}
+	c.sendPatch(patch{patchTypeReplaceURL, url})
+}
+
+// ReplaceURLf updates the browser's URL using a format string.
+func (c *Context) ReplaceURLf(format string, a ...any) {
+	c.ReplaceURL(fmt.Sprintf(format, a...))
+}
+
 // stopAllRoutines stops all go routines tied to this Context preventing goroutine leaks.
 func (c *Context) stopAllRoutines() {
 	select {

h/h.go

@@ -79,7 +79,6 @@ func HTML5(p HTML5Props) H {
 		Body:        retype(p.Body),
 		HTMLAttrs:   retype(p.HTMLAttrs),
 	}
-	gp.Head = append(gp.Head, Script(Type("module"), Src("/_datastar.js")))
 	return gc.HTML5(gp)
 }
 

internal/examples/session/main.go

@@ -7,11 +7,11 @@ import (
 
 func main() {
 	v := via.New()
+	v.Config(via.Options{ServerAddress: ":7331"})
 
-	v.Page("/", func(c *via.Context) {
-		username := c.Session().GetString("username")
+	// Login page
+	v.Page("/login", func(c *via.Context) {
 		flash := c.Session().PopString("flash")
-
 		usernameInput := c.Signal("")
 
 		login := c.Action(func() {
@@ -20,38 +20,69 @@ func main() {
 				c.Session().Set("username", name)
 				c.Session().Set("flash", "Welcome, "+name+"!")
 				c.Session().RenewToken()
+				c.Redirect("/dashboard")
 			}
-			c.Sync()
-		})
-
-		logout := c.Action(func() {
-			c.Session().Set("flash", "Goodbye!")
-			c.Session().Delete("username")
-			c.Sync()
 		})
 
 		c.View(func() h.H {
+			// Already logged in? Redirect to dashboard
+			if c.Session().GetString("username") != "" {
+				c.Redirect("/dashboard")
+				return h.Div()
+			}
+
 			var flashMsg h.H
 			if flash != "" {
 				flashMsg = h.P(h.Text(flash), h.Style("color: green"))
 			}
+			return h.Div(
+				flashMsg,
+				h.H1(h.Text("Login")),
+				h.Input(h.Type("text"), h.Placeholder("Username"), usernameInput.Bind()),
+				h.Button(h.Text("Login"), login.OnClick()),
+			)
+		})
+	})
 
+	// Dashboard page (protected)
+	v.Page("/dashboard", func(c *via.Context) {
+		logout := c.Action(func() {
+			c.Session().Set("flash", "Goodbye!")
+			c.Session().Delete("username")
+			c.Redirect("/login")
+		})
+
+		c.View(func() h.H {
+			username := c.Session().GetString("username")
+
+			// Not logged in? Redirect to login
 			if username == "" {
-				return h.Div(
-					flashMsg,
-					h.H1(h.Text("Login")),
-					h.Input(h.Type("text"), h.Placeholder("Username"), usernameInput.Bind()),
-					h.Button(h.Text("Login"), login.OnClick()),
-				)
+				c.Session().Set("flash", "Please log in first")
+				c.Redirect("/login")
+				return h.Div()
+			}
+
+			flash := c.Session().PopString("flash")
+			var flashMsg h.H
+			if flash != "" {
+				flashMsg = h.P(h.Text(flash), h.Style("color: green"))
 			}
 			return h.Div(
 				flashMsg,
-				h.H1(h.Textf("Hello, %s!", username)),
+				h.H1(h.Textf("Dashboard - Hello, %s!", username)),
 				h.P(h.Text("Your session persists across page refreshes.")),
 				h.Button(h.Text("Logout"), logout.OnClick()),
 			)
 		})
 	})
 
+	// Redirect root to login
+	v.Page("/", func(c *via.Context) {
+		c.View(func() h.H {
+			c.Redirect("/login")
+			return h.Div()
+		})
+	})
+
 	v.Start()
 }

via.go

@@ -15,6 +15,7 @@ import (
 	"io"
 	"log"
 	"net/http"
+	"net/url"
 	"os"
 	"path/filepath"
 	"strings"
@@ -31,14 +32,17 @@ var datastarJS []byte
 // V is the root application.
 // It manages page routing, user sessions, and SSE connections for live updates.
 type V struct {
-	cfg                  Options
-	mux                  *http.ServeMux
-	contextRegistry      map[string]*Context
-	contextRegistryMutex sync.RWMutex
-	documentHeadIncludes []h.H
-	documentFootIncludes []h.H
-	devModePageInitFnMap map[string]func(*Context)
-	sessionManager       *scs.SessionManager
+	cfg                       Options
+	mux                       *http.ServeMux
+	contextRegistry           map[string]*Context
+	contextRegistryMutex      sync.RWMutex
+	documentHeadIncludes      []h.H
+	documentFootIncludes      []h.H
+	devModePageInitFnMap      map[string]func(*Context)
+	sessionManager  *scs.SessionManager
+	datastarPath    string
+	datastarContent []byte
+	datastarOnce    sync.Once
 }
 
 func (v *V) logFatal(format string, a ...any) {
@@ -107,6 +111,12 @@ func (v *V) Config(cfg Options) {
 	if cfg.SessionManager != nil {
 		v.sessionManager = cfg.SessionManager
 	}
+	if cfg.DatastarContent != nil {
+		v.datastarContent = cfg.DatastarContent
+	}
+	if cfg.DatastarPath != "" {
+		v.datastarPath = cfg.DatastarPath
+	}
 }
 
 // AppendToHead appends the given h.H nodes to the head of the base HTML document.
@@ -140,6 +150,7 @@ func (v *V) AppendToFoot(elements ...h.H) {
 //		})
 //	})
 func (v *V) Page(route string, initContextFn func(c *Context)) {
+	v.ensureDatastarHandler()
 	// check for panics
 	func() {
 		defer func() {
@@ -175,7 +186,7 @@ func (v *V) Page(route string, initContextFn func(c *Context)) {
 		if v.cfg.DevMode {
 			v.devModePersist(c)
 		}
-		headElements := []h.H{}
+		headElements := []h.H{h.Script(h.Type("module"), h.Src(v.datastarPath))}
 		headElements = append(headElements, v.documentHeadIncludes...)
 		headElements = append(headElements,
 			h.Meta(h.Data("signals", fmt.Sprintf("{'via-ctx':'%s'}", id))),
@@ -257,6 +268,15 @@ func (v *V) HTTPServeMux() *http.ServeMux {
 	return v.mux
 }
 
+func (v *V) ensureDatastarHandler() {
+	v.datastarOnce.Do(func() {
+		v.mux.HandleFunc("GET "+v.datastarPath, func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Content-Type", "application/javascript")
+			_, _ = w.Write(v.datastarContent)
+		})
+	})
+}
+
 func (v *V) devModePersist(c *Context) {
 	p := filepath.Join(".via", "devmode", "ctx.json")
 	if err := os.MkdirAll(filepath.Dir(p), 0755); err != nil {
@@ -359,6 +379,8 @@ const (
 	patchTypeElements = iota
 	patchTypeSignals
 	patchTypeScript
+	patchTypeRedirect
+	patchTypeReplaceURL
 )
 
 type patch struct {
@@ -375,6 +397,8 @@ func New() *V {
 		contextRegistry:      make(map[string]*Context),
 		devModePageInitFnMap: make(map[string]func(*Context)),
 		sessionManager:       scs.New(),
+		datastarPath:         "/_datastar.js",
+		datastarContent:      datastarJS,
 		cfg: Options{
 			DevMode:       false,
 			ServerAddress: ":3000",
@@ -383,11 +407,6 @@ func New() *V {
 		},
 	}
 
-	v.mux.HandleFunc("GET /_datastar.js", func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/javascript")
-		_, _ = w.Write(datastarJS)
-	})
-
 	v.mux.HandleFunc("GET /_sse", func(w http.ResponseWriter, r *http.Request) {
 		isReconnect := false
 		if r.Header.Get("last-event-id") == "via" {
@@ -453,6 +472,21 @@ func New() *V {
 							v.logErr(c, "ExecuteScript failed: %v", err)
 						}
 					}
+				case patchTypeRedirect:
+					if err := sse.Redirect(patch.content); err != nil {
+						if sse.Context().Err() == nil {
+							v.logErr(c, "Redirect failed: %v", err)
+						}
+					}
+				case patchTypeReplaceURL:
+					parsedURL, err := url.Parse(patch.content)
+					if err != nil {
+						v.logErr(c, "ReplaceURL failed to parse URL: %v", err)
+					} else if err := sse.ReplaceURL(*parsedURL); err != nil {
+						if sse.Context().Err() == nil {
+							v.logErr(c, "ReplaceURL failed: %v", err)
+						}
+					}
 				}
 			}
 		}

via_test.go

@@ -28,6 +28,10 @@ func TestPageRoute(t *testing.T) {
 
 func TestDatastarJS(t *testing.T) {
 	v := New()
+	v.Page("/", func(c *Context) {
+		c.View(func() h.H { return h.Div() })
+	})
+
 	req := httptest.NewRequest("GET", "/_datastar.js", nil)
 	w := httptest.NewRecorder()
 	v.mux.ServeHTTP(w, req)
@@ -37,6 +41,50 @@ func TestDatastarJS(t *testing.T) {
 	assert.Contains(t, w.Body.String(), "🖕JS_DS🚀")
 }
 
+func TestCustomDatastarContent(t *testing.T) {
+	customScript := []byte("// Custom Datastar Script")
+	v := New()
+	v.Config(Options{
+		DatastarContent: customScript,
+	})
+	v.Page("/", func(c *Context) {
+		c.View(func() h.H { return h.Div() })
+	})
+
+	req := httptest.NewRequest("GET", "/_datastar.js", nil)
+	w := httptest.NewRecorder()
+	v.mux.ServeHTTP(w, req)
+
+	assert.Equal(t, http.StatusOK, w.Code)
+	assert.Equal(t, "application/javascript", w.Header().Get("Content-Type"))
+	assert.Contains(t, w.Body.String(), "Custom Datastar Script")
+}
+
+func TestCustomDatastarPath(t *testing.T) {
+	v := New()
+	v.Config(Options{
+		DatastarPath: "/assets/datastar.js",
+	})
+	v.Page("/test", func(c *Context) {
+		c.View(func() h.H { return h.Div() })
+	})
+
+	// Custom path should serve the script
+	req := httptest.NewRequest("GET", "/assets/datastar.js", nil)
+	w := httptest.NewRecorder()
+	v.mux.ServeHTTP(w, req)
+
+	assert.Equal(t, http.StatusOK, w.Code)
+	assert.Equal(t, "application/javascript", w.Header().Get("Content-Type"))
+	assert.Contains(t, w.Body.String(), "🖕JS_DS🚀")
+
+	// Page should reference the custom path in script tag
+	req2 := httptest.NewRequest("GET", "/test", nil)
+	w2 := httptest.NewRecorder()
+	v.mux.ServeHTTP(w2, req2)
+	assert.Contains(t, w2.Body.String(), `src="/assets/datastar.js"`)
+}
+
 func TestSignal(t *testing.T) {
 	var sig *signal
 	v := New()