OnStart takes a script name, and OnFinale joins it

The opening a game plays was the one piece of content that had to be
assembled in the wiring, because OnStart wanted an Action. It takes the
name of a registered Script now, so an opening is a Script like any
other, and Validate rejects a name that is not there.

OnFinale names the closing script and queues it straight after the start
one — what a "boot into the ending" debug flag wants.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

README.md

@@ -296,12 +296,29 @@ register into them instead unless that is what you want.
 
 ```go
 func (g *Game) StartAt(name string) *Game     // entry scene
-func (g *Game) OnStart(a Action) *Game        // action run after the scene's OnEnter
+func (g *Game) OnStart(script string) *Game   // script run after the scene's OnEnter
+func (g *Game) OnFinale(script string) *Game  // closing script, queued after OnStart
 func (g *Game) Validate() error               // cross-check name references
 func (g *Game) Run() error                    // same as inkwell.Run(g)
 ```
 
-`StartAt` and `OnStart` return `*Game` so they chain at the end of `Build`.
+`OnStart` and `OnFinale` name registered scripts rather than taking an action,
+so the opening a game plays is content like any other — a `Script` in the
+`ScriptManager`, reachable by name and editable without touching the wiring.
+`Validate` rejects a name that is not registered.
+
+`OnFinale` is queued directly after the start script, which is what a "boot
+straight into the ending" debug flag wants:
+
+```go
+g.StartAt(start)
+g.OnStart(ScriptOpening)
+if finale {
+    g.OnFinale(ScriptFinale)
+}
+```
+
+All three return `*Game` so they chain at the end of `Build`.
 
 ### 4.3 Theme accessors
 
@@ -1540,8 +1557,8 @@ func Run(g *Game) error                          // toplevel — same as g.Run()
 3. If `UIManager` is empty, call `RegisterDefaultUI(g)`.
 4. Place the start scene directly (no transition), bump
    `State.NoteVisit`, position registered actors, kick off music.
-5. Compose `Seq(scene.OnEnter, game.OnStart)` and queue it as the initial
-   action — the first script tick runs both in order.
+5. Compose `Seq(scene.OnEnter, OnStart script, OnFinale script)` and queue
+   it as the initial action — the first script tick runs them in order.
 6. `ebiten.SetWindowSize(Width*4, Height*4)`,
    `ebiten.SetWindowTitle(g.Title)`, then `ebiten.RunGame(&engine{g})`.
 

core.dsl.go

@@ -34,8 +34,11 @@ func Run(g *Game) error {
 	if s.OnEnter != nil {
 		seq = append(seq, s.OnEnter)
 	}
-	if g.onStart != nil {
-		seq = append(seq, g.onStart)
+	if g.onStart != "" {
+		seq = append(seq, RunScript(g.onStart))
+	}
+	if g.onFinale != "" {
+		seq = append(seq, RunScript(g.onFinale))
 	}
 	if len(seq) > 0 {
 		g.queueAction(Seq(seq...), "init")

core.game.go

@@ -42,7 +42,8 @@ type Game struct {
 	Input     *Input
 
 	startID     string
-	onStart     Action
+	onStart     string
+	onFinale    string
 	activeTheme string
 
 	// runtime
@@ -190,7 +191,15 @@ func (g *Game) SceneHotspots(name string) []Hotspot {
 	g.exitHotspots[name] = hs
 	return hs
 }
-func (g *Game) OnStart(a Action) *Game { g.onStart = a; return g }
+
+// OnStart names the script queued after the start scene's OnEnter, once,
+// when the game boots.
+func (g *Game) OnStart(script string) *Game { g.onStart = script; return g }
+
+// OnFinale names the game's closing script, queued directly after the start
+// script — which is what a "boot straight into the ending" debug flag wants.
+// Leave it unset for an ordinary run.
+func (g *Game) OnFinale(script string) *Game { g.onFinale = script; return g }
 
 // ----- theme + UI conveniences ------------------------------------------
 
@@ -327,6 +336,11 @@ func (g *Game) Validate() error {
 			}
 		}
 	}
+	for _, name := range []string{g.onStart, g.onFinale} {
+		if name != "" && !g.ScriptManager.Has(name) {
+			return fmt.Errorf("%w: %q", ErrUnknownScript, name)
+		}
+	}
 	if g.activeTheme == "" || !g.ThemeManager.Has(g.activeTheme) {
 		return fmt.Errorf("inkwell: no active theme (got %q)", g.activeTheme)
 	}