Play switches to scene tab; graph tab strictly follows selection

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

README.md

@@ -54,8 +54,11 @@ shown on the node and editable in the inspector.
   (types are checked; a data input holds one link and is replaced), drag nodes, right-click a
   node or port to delete/disconnect, `Delete` removes the selected node, wheel zooms, dragging
   the empty canvas pans. Everything is undoable.
-- **Live view**: while playing with the Graph tab open, the exec edges and nodes that just ran
-  light up – the same canvas draws editor and game, so this costs nothing extra.
+- **Selection-bound**: the Graph tab shows the behavior the current selection refers to
+  (asset, placed object or node); with nothing or a non-behavior selected it is empty.
+- **Live view**: Play always switches to the Scene tab; switch back to Graph while playing and
+  the exec edges and nodes that just ran light up – the same canvas draws editor and game, so
+  this costs nothing extra.
 - **Runtime**: `BehaviorSystem` creates one `GraphInterpreter` per behavior entity; graphs only
   touch world entities. A runaway loop throws after 1000 steps and stops play with a notice.
 

src/editor/App.ts

@@ -256,6 +256,8 @@ class Editor {
     this.world.addSystem(this.behaviors);
     this.viewport.setWorld(this.world);
     this.state.setMode('play');
+    // Play always starts on the scene; the graph tab stays reachable for live tracing.
+    this.showTab('scene');
     this.state.setNotice(this.world.firstOfType('camera') ? 'Playing · Esc stops' : 'This scene has no camera – nothing is rendered · Esc stops');
     if (this.world.stopRequested) this.stop();
   }

src/editor/graph/GraphEditor.ts

@@ -20,8 +20,8 @@ interface PortAnchor {
 
 /**
  * The node graph editor for one behavior asset. Shows the graph of whatever behavior the
- * selection refers to (asset, placed object or node) and keeps showing it while unrelated
- * things are selected, so the user can flip between Scene and Graph tabs freely.
+ * selection refers to (asset, placed object or node). When nothing or a non-behavior is
+ * selected the editor is empty – the graph strictly mirrors the selection.
  *
  * Interactions: drag nodes, drag from port to port to connect, right-click the canvas for
  * the node palette, right-click a node or port for delete/disconnect, wheel to zoom, drag
@@ -100,7 +100,7 @@ export class GraphEditor extends Widget {
       this.sync();
       this.needsFit = true;
       this.fitView();
-    } else if (!this.asset()) {
+    } else if (!wanted || !this.asset()) {
       this.assetId = null;
       this.sync();
     } else {

tools/e2e.mjs

@@ -424,9 +424,13 @@ try {
   const restored = await graphCounts();
   check('undo restores node and edge', restored.nodes === before13.nodes + 1 && restored.edges === before13.edges + 1, JSON.stringify(restored));
 
-  // 13e. Live highlight: play with the graph open, hold ArrowRight → the exec edge is hot.
+  // 13e. Play always starts on the Scene tab; switching back to Graph while playing shows
+  // the live highlight: hold ArrowRight → the exec edge is hot.
   await clickText('▶  Play');
   await sleep(200);
+  check('play switches to the scene tab', (await evaluate('__gm.tab()')) === 'scene');
+  await evaluate(`__gm.showTab('graph')`);
+  await sleep(100);
   await cdp.send('Input.dispatchKeyEvent', { type: 'keyDown', key: 'ArrowRight', code: 'ArrowRight', windowsVirtualKeyCode: 39 });
   await sleep(300);
   await shot('19-graph-live');
@@ -448,6 +452,17 @@ try {
   await sleep(150);
   const varsUndone = JSON.parse(await evaluate(`JSON.stringify(__gm.state.project.assets.find(a => a.id === 'mover').variables.map(v => v.key))`));
   check('undo removes the variable', varsUndone.join(',') === 'speed', varsUndone.join(','));
+
+  // 13g. The graph strictly mirrors the selection: nothing / a non-behavior → empty editor.
+  await evaluate(`__gm.state.select(null)`);
+  await sleep(100);
+  check('graph editor empties when nothing is selected', (await evaluate(`__gm.graph.current()`)) === null);
+  await evaluate(`__gm.state.select({ kind: 'asset', assetId: 'cam' })`);
+  await sleep(100);
+  check('graph editor stays empty for a non-behavior asset', (await evaluate(`__gm.graph.current()`)) === null);
+  await evaluate(`__gm.state.select({ kind: 'asset', assetId: 'mover' })`);
+  await sleep(100);
+  check('graph editor rebinds when a behavior is selected again', (await evaluate(`__gm.graph.current()`)) === 'mover');
   await evaluate(`__gm.showTab('scene')`);
 
   check('no exceptions during run', !consoleLog.some((l) => l.startsWith('EXCEPTION')), consoleLog.filter((l) => l.startsWith('EXCEPTION')).slice(0, 3).join(' | '));