Let a behavior be a node in another graph

A behavior that has a Start and an End node can now be dropped into any
other graph as a node of its own. What is declared on the start node
becomes the inputs of that node, what hangs on the end node its outputs;
the port list is derived from the sub graph, not copied, so declaring a
port in one graph grows the node in the other without touching it. The
node carries the behavior's name and the palette lists behaviors by
name, so a call is one grab instead of a node plus a dropdown.

An embedded behavior has no object and therefore no place for
variables: every call starts on the asset defaults and communicates
only through its ports. That is the conservative direction - state can
still be added later, and shared state already has a home in a behavior
object in the scene. Node ids are unique per graph only, so each call
gets its own pulse cache; without that, two graphs would collide.

Renaming a port used to silently drop the value typed on the calling
node. It is carried along now, project wide, like the edges.

tools/e2e/19-nested-behavior.mjs

@@ -0,0 +1,216 @@
+import { edge, node, port } from '../lib/builders.mjs';
+
+/**
+ * A behavior used as a node inside another behavior's graph: the ports it grows from the other
+ * graph's start/end nodes, the call itself while playing, and declaring a port across the two.
+ *
+ * The step brings its own box and its own two behaviors; everything it adds is removed at the end.
+ */
+
+const SCALE = 100;
+
+/** `in1` → ×2 → `out1`, entered at the start node and left at the end node. */
+const doubleGraph = {
+  nodes: [
+    node('nb-start', 'BehaviorStart', 0, 0, {}, [port('in1', 'number')]),
+    node('nb-times', 'Multiply', 240, 60, { b: 2 }),
+    node('nb-end', 'BehaviorEnd', 520, 0, {}, [port('out1', 'number')]),
+  ],
+  edges: [
+    edge('nb-e1', 'nb-start', 'exec', 'nb-end', 'exec'),
+    edge('nb-e2', 'nb-start', 'in1', 'nb-times', 'a'),
+    edge('nb-e3', 'nb-times', 'result', 'nb-end', 'out1'),
+  ],
+};
+
+/**
+ * `On update → Run(Double, in1 = 1) → Move(owner, dx = out1)`. The caller does no arithmetic of
+ * its own: the speed it moves at *is* the value the nested behavior handed back.
+ */
+const callerGraph = {
+  nodes: [
+    node('nb-update', 'OnUpdate', 0, 0),
+    node('nb-owner', 'Owner', 0, 160),
+    node('nb-call', 'RunBehavior', 260, 0, { behavior: 'nb-double', in1: 1 }),
+    node('nb-move', 'Move', 560, 0, { scale: SCALE }),
+  ],
+  edges: [
+    edge('nb-c1', 'nb-update', 'exec', 'nb-call', 'exec'),
+    edge('nb-c2', 'nb-call', 'exec', 'nb-move', 'exec'),
+    edge('nb-c3', 'nb-call', 'out1', 'nb-move', 'dx'),
+    edge('nb-c4', 'nb-update', 'dt', 'nb-move', 'dt'),
+    edge('nb-c5', 'nb-owner', 'object', 'nb-move', 'object'),
+  ],
+};
+
+export async function nestedBehavior(t) {
+  const {
+    check,
+    sleep,
+    evaluate,
+    json,
+    shot,
+    click,
+    clickText,
+    typeText,
+    locate,
+    press,
+    undo,
+    object,
+    entity,
+    asset,
+    mutate,
+    stop,
+  } = t;
+  const portAt = (nodeId, key, isOutput) =>
+    json(`__gm.graph.portAt(${JSON.stringify(nodeId)}, ${JSON.stringify(key)}, ${isOutput})`);
+  const startPorts = async () =>
+    (await asset('nb-double')).graph.nodes.find((n) => n.id === 'nb-start').ports ?? [];
+
+  // 19a. Two behaviors and a box wearing the calling one. Written into the model directly: what
+  //      is under test is the call, not another way of drawing a graph.
+  await mutate(`
+    const p = __gm.state.project;
+    const scene = __gm.state.activeScene;
+    const proto = scene.objects[0];
+    const mover = p.assets.find((a) => a.id === 'mover');
+    const behavior = (id, name, graph) => {
+      const a = structuredClone(mover);
+      Object.assign(a, { id, name, props: { enabled: true, runInEditor: false }, variables: [], graph });
+      p.assets.push(a);
+    };
+    behavior('nb-double', 'Double', ${JSON.stringify(doubleGraph)});
+    behavior('nb-caller', 'Caller', ${JSON.stringify(callerGraph)});
+    const make = (id, assetId, parentId, name) => {
+      const o = structuredClone(proto);
+      Object.assign(o, {
+        id, assetId, name,
+        position: { x: 0, y: 700, z: 0 },
+        parentId, overrides: {}, instanceEdits: {},
+      });
+      return o;
+    };
+    scene.objects.push(make('nb-box', 'crate', '', 'Nested box'), make('nb-logic', 'nb-caller', 'nb-box', 'Caller'));
+  `);
+  await sleep(400);
+
+  // 19b. The call really runs, and the value really comes back: the box moves at dx × scale, and
+  //      dx is nothing the caller holds – it is what the nested graph returned. Without the result
+  //      dx would be 0 and the box would not move at all.
+  const boxX = async () => (await object('nb-box')).position.x;
+  const idleX = await boxX();
+  await t.play();
+  await sleep(300);
+  const before = (await entity('nb-box')).x;
+  await sleep(1000);
+  const after = (await entity('nb-box')).x;
+  const speed = after - before;
+  check(
+    'a behavior used as a node runs, and what it returns is what drives the caller',
+    speed > SCALE * 1.4 && speed < SCALE * 2.6,
+    `moved ${speed.toFixed(1)} px in ~1 s – 2 × ${SCALE} means the returned value arrived, 0 would mean nothing came back`,
+  );
+  await stop();
+  await sleep(300);
+  check(
+    'the stored object is untouched by the run, as in any play session',
+    (await boxX()) === idleX,
+    `x=${await boxX()}`,
+  );
+
+  // 19c. The node in the graph carries the *other* behavior's ports and name – neither is part of
+  //      its own type.
+  await evaluate(
+    `__gm.state.select({ kind: 'node', assetId: 'nb-caller', nodeId: 'nb-call', nodeIds: ['nb-call'] })`,
+  );
+  await sleep(300);
+  const inPort = await portAt('nb-call', 'in1', false);
+  const outPort = await portAt('nb-call', 'out1', true);
+  check(
+    'the calling node grows the ports the other behavior declares',
+    Boolean(inPort) && Boolean(outPort) && outPort.x > inPort.x,
+    JSON.stringify({ inPort, outPort }),
+  );
+  const title = await evaluate(`__gm.graph.nodeLabel('nb-call')`);
+  check(
+    'and it is drawn under that behavior\'s name, not as "Run behavior"',
+    title === 'Double',
+    `title=${JSON.stringify(title)}`,
+  );
+  await shot('37-nested-behavior');
+
+  // 19d. Declaring a port on one behavior reaches the node in the other one, live. This is the
+  //      check that a port list derived from another graph is really derived and not copied.
+  check('the calling node has no second input yet', !(await portAt('nb-call', 'in2', false)));
+  await evaluate(
+    `__gm.state.select({ kind: 'node', assetId: 'nb-double', nodeId: 'nb-start', nodeIds: ['nb-start'] })`,
+  );
+  await sleep(300);
+  const addButton = await locate('+ Input');
+  check('the start node offers its inputs in the inspector', Boolean(addButton), JSON.stringify(addButton));
+  await shot('38-behavior-ports');
+  await click(addButton.x, addButton.y);
+  await sleep(200);
+  await clickText('Number');
+  await sleep(300);
+  const declared = await startPorts();
+  check(
+    'adding an input declares it on the start node',
+    declared.length === 2 && declared[1].key === 'in2' && declared[1].kind === 'number',
+    JSON.stringify(declared),
+  );
+  await evaluate(
+    `__gm.state.select({ kind: 'node', assetId: 'nb-caller', nodeId: 'nb-call', nodeIds: ['nb-call'] })`,
+  );
+  await sleep(300);
+  check(
+    'and the node in the other graph grew that input without being touched',
+    Boolean(await portAt('nb-call', 'in2', false)),
+  );
+
+  // 19e. Undo takes the port back, and with it the port on the calling node.
+  await undo();
+  await sleep(300);
+  const afterUndo = await startPorts();
+  check(
+    'undo removes it in both graphs',
+    afterUndo.length === 1 && !(await portAt('nb-call', 'in2', false)),
+    `${JSON.stringify(afterUndo)}`,
+  );
+
+  // 19f. The palette offers a behavior under its own name, and picking it leaves a node that
+  //      already names it – one pick, not a pick plus a dropdown. ("Double" also labels the asset
+  //      in the list on the left, so the proof is the node that appears, not the row.)
+  const nodeIds = async () => (await asset('nb-caller')).graph.nodes.map((n) => n.id);
+  const idsBefore = await nodeIds();
+  const centre = await json('__gm.graph.center()');
+  await click(centre.x + 250, centre.y + 250, 'right');
+  await sleep(150);
+  check('node palette opens', Boolean(await locate('Search nodes…')));
+  await typeText('Double');
+  await sleep(200);
+  // Enter takes the first match. NOT a click on the label: "Double" also names the asset in the
+  // list on the left, and that is what a click by text would find first.
+  await press('Enter');
+  await sleep(300);
+  const added = (await asset('nb-caller')).graph.nodes.find((n) => !idsBefore.includes(n.id));
+  check(
+    'picking a behavior in the palette drops in a node already set to it',
+    (await nodeIds()).length === idsBefore.length + 1 &&
+      added?.type === 'RunBehavior' &&
+      added?.params.behavior === 'nb-double',
+    JSON.stringify(added && { type: added.type, params: added.params }),
+  );
+  await undo();
+  await sleep(200);
+
+  // 19g. Clean up: the two behaviors and the box are gone again.
+  await evaluate(`__gm.state.select(null)`);
+  await mutate(`
+    const p = __gm.state.project;
+    const scene = __gm.state.activeScene;
+    p.assets = p.assets.filter((a) => a.id !== 'nb-double' && a.id !== 'nb-caller');
+    scene.objects = scene.objects.filter((o) => o.id !== 'nb-box' && o.id !== 'nb-logic');
+  `);
+  await sleep(300);
+}