Scene exits, Back(), and the current/previous scene accessors

A connection between two scenes had to be hand-built as a hotspot: an area,
a cursor, a GoTo, and a flag check written out again for every door. Scene
now carries Exits, and the engine expands each one into a hotspot.

- Exit{To, Label, Side, Area, Needs, Blocked, OnLook, OnTake} in scene.exit.go.
  With no Area an exit is an edge strip, sized as a fraction of Game.SceneArea()
  so a game whose HUD covers the foot of the window gets strips inside the
  painting. Game.ExitLook / Game.ExitTake supply the look and take responses
  once for the whole game, so the phrasing is not repeated per exit.
- Game.SceneHotspots(name) is the scene's own hotspots followed by its exits,
  cached per scene. Authored hotspots come first, so a painted thing beats the
  edge strip wherever the two overlap. HotspotAt and HotspotDebug read it.
- Game.CurrentScene() / PreviousScene(), both persisted in the save file. The
  engine tracked the current scene but exposed no accessor, so every game had
  to shadow it to know where it was.
- Back() returns to the previous scene — what an exit with an empty To binds
  to, for a scene reachable from several rooms whose way out is a direction
  rather than a place.
- Validate rejects an exit naming a scene nobody registered.

Generated hotspots are named ExitName(To) ("exit:street", "exit:back"), so the
location graph can be read straight back out of the registered scenes.

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

README.md

@@ -30,14 +30,15 @@ import "git.teletypegames.org/games/inkwell"
 6. [Entity reference](#6-entity-reference)
    - 6.1 [Asset](#61-asset)
    - 6.2 [Scene](#62-scene)
-   - 6.3 [Hotspot](#63-hotspot)
-   - 6.4 [Trigger](#64-trigger)
-   - 6.5 [Item](#65-item)
-   - 6.6 [Inventory](#66-inventory)
-   - 6.7 [Character](#67-character)
-   - 6.8 [Dialogue](#68-dialogue)
-   - 6.9 [Script](#69-script)
-   - 6.10 [Verb](#610-verb)
+   - 6.3 [Exit](#63-exit)
+   - 6.4 [Hotspot](#64-hotspot)
+   - 6.5 [Trigger](#65-trigger)
+   - 6.6 [Item](#66-item)
+   - 6.7 [Inventory](#67-inventory)
+   - 6.8 [Character](#68-character)
+   - 6.9 [Dialogue](#69-dialogue)
+   - 6.10 [Script](#610-script)
+   - 6.11 [Verb](#611-verb)
 7. [The action system](#7-the-action-system)
    - 7.1 [Action and Runner](#71-action-and-runner)
    - 7.2 [Status and Ctx](#72-status-and-ctx)
@@ -237,6 +238,11 @@ type Game struct {
     UIManager        *UIManager
     ThemeManager     *ThemeManager
 
+    // exits
+    SceneRect Rectangle          // the part of the window the picture occupies
+    ExitLook  func(Exit) Action  // default look response for generated exits
+    ExitTake  func(Exit) Action  // default take response for generated exits
+
     // runtime services
     State     *State
     Inventory *Inventory
@@ -330,11 +336,28 @@ func (g *Game) Messages() []LogMessage
 ### 4.6 Scene helpers
 
 ```go
+func (g *Game) CurrentScene() string
+func (g *Game) PreviousScene() string
+func (g *Game) SceneArea() Rectangle
+func (g *Game) SceneHotspots(name string) []Hotspot
+func (g *Game) HotspotAt(p Point) *Hotspot
 func (g *Game) CharacterInScene(name string) bool
 ```
 
-Used by `CharacterPanel` to auto-hide when its character isn't an actor in
-the current scene.
+`CurrentScene` is where the player is, empty before the first scene is
+entered; `PreviousScene` is the one before it, which is where
+[`Back()`](#73-built-in-actions) leads. Both survive a save.
+
+`SceneArea` is `SceneRect`, or the whole window when it was never set. It is
+what [exit strips](#63-exit) are measured against.
+
+`SceneHotspots` is everything clickable in a scene: its own `Hotspots` first,
+then one per `Exit`. Authored hotspots come first because the engine takes the
+first area that contains the click, so a painted thing beats the edge strip an
+exit sits on wherever the two overlap. The expansion is cached per scene.
+
+`CharacterInScene` is used by `CharacterPanel` to auto-hide when its character
+isn't an actor in the current scene.
 
 ### 4.7 Text drawing hook
 
@@ -428,6 +451,7 @@ type Scene struct {
     Background string         // Asset.Name
     Music      string         // Asset.Name (optional)
     Hotspots   []Hotspot
+    Exits      []Exit         // connections to other scenes
     Walkboxes  []Polygon
     Triggers   []Trigger
     Actors     []SceneActor
@@ -450,12 +474,84 @@ routes through a BFS over the polygon adjacency graph (polygons that
 share an edge are neighbours), with the midpoint of each shared edge
 used as a waypoint. Destinations outside every walkbox are clipped to
 the nearest boundary. With no walkboxes the character walks in a
-straight line — see [§6.7](#67-character) and [§15.4](#154-character-movement).
+straight line — see [§6.8](#68-character) and [§15.4](#154-character-movement).
 
 `Triggers` fire on the rising edge of their `When` condition. The
-engine samples each trigger once per idle frame; see [§6.4](#64-trigger).
+engine samples each trigger once per idle frame; see [§6.5](#65-trigger).
 
-### 6.3 Hotspot
+`Exits` are the scene's connections to other scenes, declared as data. The
+engine turns each one into a hotspot — see [§6.3](#63-exit).
+
+### 6.3 Exit
+
+```go
+// inkwell/scene.exit.go
+
+type Exit struct {
+    To      string      // target scene; empty means "back the way you came"
+    Label   string      // what the status line calls it
+    Side    ExitSide    // where it sits when Area is nil
+    Area    Shape       // overrides the edge strip Side would give it
+    Needs   string      // flag that has to be set before it opens
+    Blocked Action      // what happens while it is not
+    OnLook  Action      // overrides Game.ExitLook for this exit
+    OnTake  Action      // overrides Game.ExitTake for this exit
+}
+
+type ExitSide int
+const (
+    ExitLeft  ExitSide = iota // off the left edge
+    ExitRight                 // off the right edge
+    ExitBack                  // into the depth of the picture
+    ExitNear                  // out towards the camera
+)
+
+func ExitName(to string) string
+```
+
+A connection belongs to the scene it leads out of, so it is written in that
+scene's own literal rather than in a map kept somewhere else:
+
+```go
+Scene{
+    Name: "alley",
+    Exits: []Exit{
+        {To: "noodle_house", Label: "back out to the street", Side: ExitLeft},
+        {To: "", Label: "the fire escape", Side: ExitBack,
+         Needs: "has_ladder", Blocked: Say("paul", "Can't reach it.")},
+    },
+}
+```
+
+The engine expands each exit into a `Hotspot` with `Cursor: CursorExit`, the
+exit's `Label`, `OnUse` bound to `GoTo(To)` — or [`Back()`](#73-built-in-actions)
+when `To` is empty — and, when `Needs` is set, the whole travel wrapped in
+`If(Flag(Needs), travel, Blocked)`. The exit is visible either way: a locked
+door still says it is a door.
+
+`OnLook` and `OnTake` are usually not written per exit. `Game.ExitLook` and
+`Game.ExitTake` supply them for every exit in the game, so the phrasing lives
+in one place:
+
+```go
+g.ExitLook = func(e Exit) Action { return Say("paul", "That way: "+e.Label+".") }
+g.ExitTake = func(e Exit) Action { return Say("paul", "It's a way out, not a thing.") }
+```
+
+**Placement.** With no `Area`, an exit is a strip along one edge of the
+picture, sized as a fraction of [`Game.SceneArea()`](#46-scene-helpers) — the
+convention every 1990s point & click used, and one field to re-aim at a real
+door once the artwork is measured. A game whose HUD covers the foot of the
+window sets `Game.SceneRect`, so the strips land inside the painting instead of
+under the HUD.
+
+**The graph stays readable.** The generated hotspot is named
+`ExitName(To)` — `"exit:noodle_house"`, or `"exit:back"` — so the location
+graph can be read straight back out of the registered scenes, and
+[`Validate`](#17-validation) rejects an exit that names a scene nobody
+registered.
+
+### 6.4 Hotspot
 
 ```go
 // inkwell/scene.hotspot.go
@@ -497,7 +593,7 @@ resolves a click via `hotspot.handler(verbName)` which maps the four
 built-in verbs to their `On*` fields and falls back to `OnVerb[verbName]`
 for custom verbs.
 
-### 6.4 Trigger
+### 6.5 Trigger
 
 ```go
 // inkwell/scene.trigger.go
@@ -522,7 +618,7 @@ frame — the edge is preserved across the busy window. Save/Load resets
 trigger state to "freshly armed", matching the behaviour of scene
 re-entry.
 
-### 6.5 Item
+### 6.6 Item
 
 ```go
 // inkwell/item.def.go
@@ -545,7 +641,7 @@ hotspot with an item selected resolves the action via, in order:
 2. `item.OnUseWith[hotspot.Name]`
 3. Otherwise the engine flashes "Nem ehhez." and deselects.
 
-### 6.6 Inventory
+### 6.7 Inventory
 
 ```go
 // inkwell/item.inventory.go
@@ -564,7 +660,7 @@ func (i *Inventory) Items() []string           // copy
 Not a manager — pure runtime state owned by `Game`. Mutated by actions
 (`Give`, `TakeAway`) and by the `InventoryBar` widget on click.
 
-### 6.7 Character
+### 6.8 Character
 
 ```go
 // inkwell/actor.def.go
@@ -605,7 +701,7 @@ Movement is driven by the `Walk` action and `Game.tickCharacters` —
 stepping at `Speed` pixels/sec (default 60) along the waypoint list
 computed by [walkbox routing](#62-scene).
 
-### 6.8 Dialogue
+### 6.9 Dialogue
 
 ```go
 // inkwell/dialog.def.go
@@ -647,7 +743,7 @@ The dialog flow:
 5. `EndDialogue()` closes the conversation; `GotoNode("other")` jumps to
    another node in the same dialogue.
 
-### 6.9 Script
+### 6.10 Script
 
 ```go
 // inkwell/action.script.go
@@ -662,7 +758,7 @@ A `Script` is just a named composite action — useful when you want to
 reuse a cutscene (intro, victory, transition) from multiple call sites.
 Fire one with `RunScript("name")`.
 
-### 6.10 Verb
+### 6.11 Verb
 
 ```go
 // inkwell/ui.verb.go
@@ -749,6 +845,7 @@ type Ctx struct {
 | `Wait(seconds float64) Action`           | Block the runner for `seconds`.                                            |
 | `Say(speaker, text string) Action`       | Show the line above the speaker (`SpeechBubble`), append to chat-log. Click-to-skip. Duration scales with text length, 1.2s floor. |
 | `GoTo(scene string) Action`              | Switch the current scene via a fade transition.                            |
+| `Back() Action`                          | Return to `PreviousScene()`. No-op when there is nowhere to go back to.    |
 | `Walk(character string, to Point) Action`| Move a character to `to` at `Character.Speed`. Returns when arrived.       |
 | `Give(item string) Action`               | Add `item` to inventory.                                                   |
 | `TakeAway(item string) Action`           | Remove `item` from inventory.                                              |
@@ -1530,6 +1627,8 @@ It cross-checks:
   `Asset`.
 - Optional `Scene.Music` (if non-empty) references a registered `Asset`.
 - Every `SceneActor.CharacterName` is a registered character.
+- Every `Scene.Exit.To` names a registered scene (empty is allowed — it
+  means "back the way you came").
 - An active theme is selected and registered.
 
 Returns the first error wrapping one of the `Err...` sentinels (so callers
@@ -1551,7 +1650,7 @@ Slots are written as JSON files under `g.SaveDir` (default `saves/`,
 relative to the working directory), one file per slot named
 `slot<N>.json`. The save captures the **mutable runtime state**:
 
-- `currentScene`, the active verb, and the active theme.
+- `currentScene` and `previousScene`, the active verb, and the active theme.
 - Every character's position, target, and moving flag.
 - The full `State`: flags, vars, visited and talked counters.
 - The inventory item list plus the currently selected slot.
@@ -1675,6 +1774,7 @@ inkwell/                            # module git.teletypegames.org/games/inkwell
 ├── scene.def.go                   # Scene, SceneActor
 ├── scene.manager.go               # SceneManager alias
 ├── scene.hotspot.go               # Hotspot, CursorKind
+├── scene.exit.go                  # Exit, ExitSide + edge-strip geometry
 ├── scene.trigger.go               # Trigger + rising-edge engine sweep
 ├── scene.path.go                  # walkbox routing (BFS over polygon adjacency)
 ├── scene.transition.go            # fade-to-black overlay (internal)

action.def.go

@@ -250,6 +250,24 @@ func (a *gotoAction) Tick(ctx *Ctx) Status {
 	return StatusDone
 }
 
+// ----- Back -------------------------------------------------------------
+
+type backAction struct{}
+
+// Back returns to the scene the player came from. Most exits name their
+// destination, because a door leads where it leads; a scene reached from
+// several different rooms cannot, so its way out is a direction, not a place.
+// A no-op when there is nowhere to go back to.
+func Back() Action { return backAction{} }
+
+func (a backAction) Start() Runner { return a }
+func (a backAction) Tick(ctx *Ctx) Status {
+	if prev := ctx.Game.PreviousScene(); prev != "" {
+		ctx.Game.changeScene(prev)
+	}
+	return StatusDone
+}
+
 // ----- inventory --------------------------------------------------------
 
 type giveAction struct{ item string }

core.game.go

@@ -24,6 +24,17 @@ type Game struct {
 	UIManager        *UIManager
 	ThemeManager     *ThemeManager
 
+	// SceneRect is the part of the window the picture occupies. Zero means
+	// the whole window. A game with a HUD along the foot sets it, so that
+	// generated exit strips (see scene.exit.go) land inside the painting.
+	SceneRect Rectangle
+
+	// ExitLook and ExitTake supply the default look and take responses for
+	// every hotspot generated from Scene.Exits. Nil means no response.
+	// An Exit can override either one.
+	ExitLook func(Exit) Action
+	ExitTake func(Exit) Action
+
 	State     *State
 	Inventory *Inventory
 	Audio     *AudioPlayer
@@ -35,21 +46,23 @@ type Game struct {
 	activeTheme string
 
 	// runtime
-	loaded       *loadedAssets
-	currentScene string
-	chars        map[string]*runtimeChar
-	scriptRunner Runner
-	scriptCtx    *Ctx
-	transition   *transition
-	selectedVerb string
+	loaded        *loadedAssets
+	currentScene  string
+	previousScene string
+	exitHotspots  map[string][]Hotspot
+	chars         map[string]*runtimeChar
+	scriptRunner  Runner
+	scriptCtx     *Ctx
+	transition    *transition
+	selectedVerb  string
 
 	// UI runtime state (read by widgets, written by actions / engine)
-	hoverLabel string
-	flash      string
-	flashTimer float64
-	endCard    string
-	speech     speechState
-	dialog     *runtimeDialog
+	hoverLabel   string
+	flash        string
+	flashTimer   float64
+	endCard      string
+	speech       speechState
+	dialog       *runtimeDialog
 	activeDialog string
 
 	// in-game message log for ChatLog widgets; ring buffer behavior.
@@ -76,7 +89,7 @@ const (
 
 // LogMessage is a single line in the chat-log buffer.
 type LogMessage struct {
-	Speaker string  // empty for actions / system
+	Speaker string // empty for actions / system
 	Text    string
 	Kind    LogKind
 }
@@ -135,16 +148,55 @@ func NewGame(title string, w, h int) *Game {
 }
 
 func (g *Game) StartAt(name string) *Game { g.startID = name; return g }
-func (g *Game) OnStart(a Action) *Game    { g.onStart = a; return g }
+
+// CurrentScene is the scene the player is in, empty before the first one is
+// entered. PreviousScene is the one before it, which is where Back() leads.
+func (g *Game) CurrentScene() string  { return g.currentScene }
+func (g *Game) PreviousScene() string { return g.previousScene }
+
+// SceneArea is SceneRect, or the whole window when it was never set.
+func (g *Game) SceneArea() Rectangle {
+	if g.SceneRect.W > 0 && g.SceneRect.H > 0 {
+		return g.SceneRect
+	}
+	return Rect(0, 0, float64(g.Width), float64(g.Height))
+}
+
+// SceneHotspots is everything clickable in a scene: its own hotspots first,
+// then one per Exit. Authored hotspots come first because the engine takes the
+// first area that contains the click, so a painted thing beats the edge strip
+// an exit sits on wherever the two overlap.
+//
+// The expansion is cached, so the pointers HotspotAt hands out stay valid.
+func (g *Game) SceneHotspots(name string) []Hotspot {
+	if hs, ok := g.exitHotspots[name]; ok {
+		return hs
+	}
+	s, ok := g.SceneManager.Get(name)
+	if !ok {
+		return nil
+	}
+	hs := make([]Hotspot, 0, len(s.Hotspots)+len(s.Exits))
+	hs = append(hs, s.Hotspots...)
+	for _, e := range s.Exits {
+		hs = append(hs, e.hotspot(g))
+	}
+	if g.exitHotspots == nil {
+		g.exitHotspots = make(map[string][]Hotspot)
+	}
+	g.exitHotspots[name] = hs
+	return hs
+}
+func (g *Game) OnStart(a Action) *Game { g.onStart = a; return g }
 
 // ----- theme + UI conveniences ------------------------------------------
 
-func (g *Game) Theme() Theme            { return g.ThemeManager.MustGet(g.activeTheme) }
-func (g *Game) UseTheme(name string)    { g.activeTheme = name }
-func (g *Game) SelectedVerb() string    { return g.selectedVerb }
+func (g *Game) Theme() Theme             { return g.ThemeManager.MustGet(g.activeTheme) }
+func (g *Game) UseTheme(name string)     { g.activeTheme = name }
+func (g *Game) SelectedVerb() string     { return g.selectedVerb }
 func (g *Game) SetSelectedVerb(s string) { g.selectedVerb = s }
-func (g *Game) HoverLabel() string      { return g.hoverLabel }
-func (g *Game) SetHoverLabel(s string)  { g.hoverLabel = s }
+func (g *Game) HoverLabel() string       { return g.hoverLabel }
+func (g *Game) SetHoverLabel(s string)   { g.hoverLabel = s }
 
 // SetSpeech / ClearSpeech are called by the Say action; widgets render
 // whatever the current state says.
@@ -194,9 +246,9 @@ func (g *Game) HotspotAt(p Point) *Hotspot {
 	if g.currentScene == "" {
 		return nil
 	}
-	s := g.SceneManager.MustGet(g.currentScene)
-	for i := range s.Hotspots {
-		h := &s.Hotspots[i]
+	hs := g.SceneHotspots(g.currentScene)
+	for i := range hs {
+		h := &hs[i]
 		if h.Area != nil && h.Area.Contains(p) {
 			return h
 		}
@@ -266,6 +318,11 @@ func (g *Game) Validate() error {
 				return fmt.Errorf("%w: scene %q actor %q", ErrUnknownCharacter, name, a.CharacterName)
 			}
 		}
+		for _, e := range s.Exits {
+			if e.To != "" && !g.SceneManager.Has(e.To) {
+				return fmt.Errorf("%w: scene %q exit to %q", ErrUnknownScene, name, e.To)
+			}
+		}
 	}
 	if g.activeTheme == "" || !g.ThemeManager.Has(g.activeTheme) {
 		return fmt.Errorf("inkwell: no active theme (got %q)", g.activeTheme)
@@ -309,6 +366,9 @@ func (g *Game) changeScene(name string) {
 	}
 	prev := g.currentScene
 	g.transition.start(func() {
+		if prev != "" && prev != name {
+			g.previousScene = prev
+		}
 		if prev != "" {
 			old := g.SceneManager.MustGet(prev)
 			if old.OnLeave != nil {

scene.def.go

@@ -6,6 +6,7 @@ type Scene struct {
 	Background string // Asset.Name
 	Music      string // Asset.Name (optional)
 	Hotspots   []Hotspot
+	Exits      []Exit // connections to other scenes; see scene.exit.go
 	Walkboxes  []Polygon
 	Triggers   []Trigger
 	Actors     []SceneActor

scene.exit.go

@@ -0,0 +1,121 @@
+package inkwell
+
+// ExitSide is where on the picture an exit sits when it has no Area of its
+// own: off one edge, into the depth of the picture, or out towards the
+// camera. Until the doors are measured on the artwork, an edge strip is the
+// convention every 1990s point & click used, and re-aiming an exit at a real
+// door later is a one-field change.
+type ExitSide int
+
+const (
+	ExitLeft  ExitSide = iota // off the left edge
+	ExitRight                 // off the right edge
+	ExitBack                  // into the depth of the picture
+	ExitNear                  // out towards the camera
+)
+
+// Exit is one way out of a scene. The engine turns it into a Hotspot, so a
+// connection can be declared as data — where it leads, what the status line
+// calls it, and what has to be true before it opens — instead of being spelled
+// out as another hand-built hotspot.
+//
+// A connection stays machine-readable: the generated hotspot is named
+// ExitName(To), so the location graph can be read straight back out of the
+// registered scenes.
+type Exit struct {
+	// To is the scene the exit leads to. Empty means "back the way you came" —
+	// for a scene reachable from several others, where the way out is a
+	// direction rather than a place.
+	To string
+
+	// Label is what the status line calls it.
+	Label string
+
+	// Side places the exit when Area is nil.
+	Side ExitSide
+
+	// Area overrides the edge strip Side would give it.
+	Area Shape
+
+	// Needs is a flag that has to be set before the exit opens; Blocked is
+	// what happens while it is not. The exit is visible either way — a locked
+	// door still says it is a door.
+	Needs   string
+	Blocked Action
+
+	// OnLook and OnTake override Game.ExitLook and Game.ExitTake for this one
+	// exit.
+	OnLook Action
+	OnTake Action
+}
+
+// ExitName is the hotspot name generated for an exit to the named scene.
+func ExitName(to string) string {
+	if to == "" {
+		return "exit:back"
+	}
+	return "exit:" + to
+}
+
+func (e Exit) hotspot(g *Game) Hotspot {
+	var travel Action = GoTo(e.To)
+	if e.To == "" {
+		travel = Back()
+	}
+	if e.Needs != "" {
+		if e.Blocked != nil {
+			travel = If(Flag(e.Needs), travel, e.Blocked)
+		} else {
+			travel = If(Flag(e.Needs), travel)
+		}
+	}
+	area := e.Area
+	if area == nil {
+		area = e.Side.area(g.SceneArea())
+	}
+	look, take := e.OnLook, e.OnTake
+	if look == nil && g.ExitLook != nil {
+		look = g.ExitLook(e)
+	}
+	if take == nil && g.ExitTake != nil {
+		take = g.ExitTake(e)
+	}
+	return Hotspot{
+		Name:   ExitName(e.To),
+		Label:  e.Label,
+		Area:   area,
+		Cursor: CursorExit,
+		OnLook: look,
+		OnUse:  travel,
+		OnTake: take,
+	}
+}
+
+// The edge strips, as fractions of the scene area, so a game that hands over
+// only part of the window to the picture (a HUD along the foot, letterbox
+// bars) gets strips that sit inside the picture rather than under the HUD.
+const (
+	exitEdgeWidth  = 0.0875
+	exitEdgeInset  = 0.080
+	exitEdgeHeight = 0.876
+	exitDoorWidth  = 0.275
+	exitBackInset  = 0.033
+	exitBackHeight = 0.347
+	exitNearHeight = 0.198
+)
+
+func (s ExitSide) area(r Rectangle) Shape {
+	edge := r.W * exitEdgeWidth
+	door := r.W * exitDoorWidth
+	doorX := r.X + (r.W-door)/2
+	switch s {
+	case ExitLeft:
+		return Rect(r.X, r.Y+r.H*exitEdgeInset, edge, r.H*exitEdgeHeight)
+	case ExitRight:
+		return Rect(r.X+r.W-edge, r.Y+r.H*exitEdgeInset, edge, r.H*exitEdgeHeight)
+	case ExitBack:
+		return Rect(doorX, r.Y+r.H*exitBackInset, door, r.H*exitBackHeight)
+	default:
+		return Rect(doorX, r.Y+r.H*(1-exitNearHeight), door, r.H*exitNearHeight)
+	}
+}

state.save.go

@@ -15,14 +15,15 @@ const saveVersion = 1
 // runtime mutable state lands here — managers, themes and assets are
 // reconstructed by the domain's Build() on every launch.
 type saveFile struct {
-	Version      int                  `json:"version"`
-	Title        string               `json:"title"`
-	CurrentScene string               `json:"current_scene"`
-	SelectedVerb string               `json:"selected_verb"`
-	ActiveTheme  string               `json:"active_theme"`
-	Characters   map[string]savedChar `json:"characters"`
-	Inventory    savedInventory       `json:"inventory"`
-	State        savedState           `json:"state"`
+	Version       int                  `json:"version"`
+	Title         string               `json:"title"`
+	CurrentScene  string               `json:"current_scene"`
+	PreviousScene string               `json:"previous_scene"`
+	SelectedVerb  string               `json:"selected_verb"`
+	ActiveTheme   string               `json:"active_theme"`
+	Characters    map[string]savedChar `json:"characters"`
+	Inventory     savedInventory       `json:"inventory"`
+	State         savedState           `json:"state"`
 }
 
 type savedChar struct {
@@ -95,12 +96,13 @@ func (g *Game) Load(slot int) error {
 
 func (g *Game) buildSave() saveFile {
 	sf := saveFile{
-		Version:      saveVersion,
-		Title:        g.Title,
-		CurrentScene: g.currentScene,
-		SelectedVerb: g.selectedVerb,
-		ActiveTheme:  g.activeTheme,
-		Characters:   make(map[string]savedChar, len(g.chars)),
+		Version:       saveVersion,
+		Title:         g.Title,
+		CurrentScene:  g.currentScene,
+		PreviousScene: g.previousScene,
+		SelectedVerb:  g.selectedVerb,
+		ActiveTheme:   g.activeTheme,
+		Characters:    make(map[string]savedChar, len(g.chars)),
 		Inventory: savedInventory{
 			Items:    g.Inventory.Items(),
 			Selected: g.Inventory.Selected(),
@@ -142,6 +144,7 @@ func (g *Game) applySave(sf *saveFile) error {
 	g.flashTimer = 0
 
 	g.currentScene = sf.CurrentScene
+	g.previousScene = sf.PreviousScene
 	if sf.SelectedVerb != "" {
 		g.selectedVerb = sf.SelectedVerb
 	}

ui.hotspot_debug.go

@@ -36,8 +36,7 @@ func (h *HotspotDebug) Draw(dst *ebiten.Image, ctx *UICtx) {
 		return
 	}
 	col := g.Theme().HotspotOutline
-	s := g.SceneManager.MustGet(g.currentScene)
-	for _, hs := range s.Hotspots {
+	for _, hs := range g.SceneHotspots(g.currentScene) {
 		b := hs.Area.Bounds()
 		vector.StrokeRect(dst, float32(b.X), float32(b.Y), float32(b.W), float32(b.H), 1, col, false)
 		if hs.Label != "" {