A shared value belongs to the run, so a declaration carries its scope (#91)

A variable or a state machine declared `global` keeps one value for the whole
run instead of one per behavior instance. The scope sits on the declaration --
`PropertyDef.scope` and `StateMachineAsset.scope`, both optional, absence
meaning `local` -- and `local` is never written, so every project made before
this saves back unchanged.

**The name is the key.** Two behaviors declaring a global `score` mean one
variable; a behavior declaring `score` locally keeps its own. Kinds that
disagree about one global name stop the run before it starts, with the two
behaviors named; starting values that disagree are a warning on the behavior
that declares it, and the first declaration wins (`globalConflicts`).

The runtime needs no redirection layer. A global variable falls out of
`schemaForObject`, so it never reaches `entity.props` -- and then the whole rule
is "whoever declares the name takes their own value" (`graph/sharedState.ts`).
The `Variables` node is untouched and stays transparent: switching a variable to
global breaks no existing graph, because `GraphInterpreter.readAll` builds a
fresh object per read anyway and only asks `port.key in all`.

That same cut answers the inspector. A shared value has no owner, so the placed
object shows no row for it and can hold no override -- `SetVariableScopeCommand`
takes the deviations that were there and undo gives them back.

Both places say it in words rather than leaving a glyph to be guessed: the
declaration explains the mark below the list, and the placed object names the
variable it no longer holds instead of claiming the behavior declares none --
which is what it said before, untruthfully. Screenshots of the e2e run turned
that up; no check had been looking at it.

`SharedState` hangs off `NodeContext`, is built in `BehaviorSystem.start()` from
the *declarations* rather than from any instance (a global variable exists
before its behavior is placed), and is thrown away with the run: nothing is
written back, not even in the editor run. `GraphInterpreter.call` passes it on
through `...ctx` while nested calls keep getting fresh local variables, which is
why `program.defaults` is stripped of global keys.

Two traps this hit. `defSignature`/`assetSignature` have to carry the scope or
the inspector does not rebuild after the switch -- and a state machine has no
rows at all, so its scope is appended to the signature by hand. And the object
inspector does not go through `schemaForObject` for behaviors, it reads
`asset.variables` directly; filtering in one place was not enough, and no unit
test covered that path. The e2e caught it (`global: true` where false belonged),
and the rule now lives in one named function, `objectRows`.

Scopes `object` and `scene` are deliberately not built. The object case already
has a route (`Object by name` -> `Properties`), and a run knows exactly one
scene, so `scene` would be indistinguishable from `global` until #39 exists.

Closes #59: a machine's scope is a word on the machine asset, not a setting per
`Set state` node, so the same machine cannot live in two places at once.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/editor/inspector/objectSection.ts

@@ -24,6 +24,7 @@ import {
 } from '../../core/model/instance';
 import type { PropertyValue } from '../../core/model/Properties';
 import { findAsset, findObjectHolder, type Project } from '../../core/model/Project';
+import { isGlobal } from '../../core/model/Scope';
 import type { SceneObject } from '../../core/model/SceneObject';
 import {
   COMMON_PROPS,
@@ -52,6 +53,17 @@ import { buildVariable } from './variableRows';
 import { currentProps, currentRef, deviations, positionMoved, targetOf, viewOf } from './objectQueries';
 import { componentRow, OFFSET_AXES, offsetKey, POSITION_AXES } from './vectorRows';
 
+/**
+ * The rows a placed object shows for what it was placed from: a behavior's declared variables, any
+ * other asset's schema minus the common switches. A global variable is none of them – it belongs to
+ * the run, so this object has no value of its own to show or override.
+ */
+export function objectRows(project: Project, asset: Asset, object: SceneObject): PropertyDef[] {
+  return asset.type === 'behavior'
+    ? asset.variables.filter((def) => !isGlobal(def))
+    : schemaForObject(project, asset, object).filter((def) => !isCommonProp(def.key));
+}
+
 /** Structure-defining facts of an object selection: parent, template link and schema. */
 export function objectSignature(
   project: Project,
@@ -186,14 +198,17 @@ export function buildObjectSection(host: InspectorHost, holderId: string, object
 
   // Asset properties (or behavior variables) with overrides; the switches are shown above.
   const values = resolveSceneObjectProps(host.state.project, asset, object);
-  const own =
-    asset.type === 'behavior'
-      ? asset.variables
-      : schemaForObject(host.state.project, asset, object).filter((def) => !isCommonProp(def.key));
+  const own = objectRows(host.state.project, asset, object);
   if (own.length > 0 || asset.type === 'behavior')
     addTitle(host, asset.type === 'behavior' ? 'VARIABLES' : 'PROPERTIES');
-  if (own.length === 0 && asset.type === 'behavior') addNote(host, 'The behavior declares no variables.');
+  // A global variable is missing from the rows above but not from the behavior, so saying it
+  // declares none would be untrue – name it instead, and where it went.
+  const shared = asset.type === 'behavior' ? asset.variables.filter(isGlobal) : [];
+  if (own.length === 0 && shared.length === 0 && asset.type === 'behavior')
+    addNote(host, 'The behavior declares no variables.');
   for (const def of own) propertyRow(host, holderId, objectId, asset, def, values, asset.type === 'behavior');
+  if (shared.length > 0)
+    addNote(host, `Shared by the whole run: ${shared.map((def) => def.key).join(', ')}.`, 'small');
   markObjectRows(host, object, asset, target);
 
   if (asset.type === 'container') contentSection(host, holderId, object, asset.objects.length);