Discover custom ViewModels and validate Computed bindings in shared hosts

docs/binding-discovery.md

@@ -1,6 +1,6 @@
 # Shared Model and binding-target discovery
 
-This is the first stage-4 implementation slice: a read-only binding browser shared by standalone and IntelliJ. The [DirectBinding inspector](direct-binding-inspector.md) now uses discovered targets to start editable declarations. [Converter discovery and DirectBinding validation](converter-validation.md) now extend this slice; generated metadata and the complete inspector remain subsequent work.
+This is the first stage-4 implementation slice: a read-only binding browser shared by standalone and IntelliJ. The [DirectBinding inspector](direct-binding-inspector.md) now uses discovered targets to start editable declarations. [Converter discovery and DirectBinding validation](converter-validation.md) now extend this slice; [custom ViewModel and Computed metadata](viewmodel-computed-validation.md) extend discovery further. Generated metadata and the complete inspector remain subsequent work.
 
 ## Use
 
@@ -12,9 +12,9 @@ For Person the browser exposes `name`, `rank`, `home`, `home.street`, and `visit
 
 ## Metadata boundary
 
-The fresh target worker loads classes without initialization and inspects signatures. It never constructs Models, Controllers, providers, controls or Converters, never invokes getters/property accessors, and never starts JavaFX. Application types stay outside both hosts. The independently negotiated `bindings-v2` capability adds the BINDINGS operation; it uses bounded UTF-8 metadata, build/context identity and document revisions, with zero image dimensions. Existing wire operation ordinals remain unchanged.
+The fresh target worker loads classes without initialization and inspects signatures. It never constructs Models, Controllers, providers, controls or Converters, never invokes getters/property accessors, and never starts JavaFX. Application types stay outside both hosts. The independently negotiated `bindings-v3` capability adds the BINDINGS operation; it uses bounded UTF-8 metadata, build/context identity and document revisions, with zero image dimensions. Existing wire operation ordinals remain unchanged.
 
-Model fallback follows NeitzelLib's public read/write JavaBean Attribute rules and simple/complex/collection classification. Nested paths expand to depth four with cycle diagnostics; collection paths expose declared element types without pretending a collection is a single nested Model. Explicit custom BeanInfo is not executed: types requiring it report a generated-metadata diagnostic. This slice does not yet expose custom/replacement ViewModel members, generated metadata, Computed methods or library-provided message properties. Its compatibility results describe the Model-Attribute binding case, not the complete custom ViewModel API.
+Model fallback follows NeitzelLib's public read/write JavaBean Attribute rules and simple/complex/collection classification. Nested paths expand to depth four with cycle diagnostics; collection paths expose declared element types without pretending a collection is a single nested Model. Explicit custom BeanInfo is not executed: types requiring it report a generated-metadata diagnostic. Custom/replacement ViewModels, built-in message properties and Computed methods now follow the [signature-based selection rules](viewmodel-computed-validation.md). Generated metadata and arbitrary dynamic property APIs remain unresolved.
 
 Targets come from public instance JavaFX observable-property accessors. The runtime requires writable `Property` accessors, so read-only targets remain visible as incompatible. Generic observable signatures and getter types identify the value type; incomplete or contradictory signatures remain unresolved. Component `model` targets use the Component resource's explicit Model declaration instead of treating Object as a specific type. Component resource metadata comes from the selected build; current-document metadata comes from the captured draft.
 
@@ -24,7 +24,7 @@ Compatibility uses boxed declared types and target-runtime assignability: `view`
 
 Discovery owns a separate workflow so it does not replace the canvas or interactive worker. It uses a leased successful build and a captured current-document overlay. Generation and document-revision checks reject obsolete replies. Document changes clear the target list and require rediscovery; Build and Refresh invalidates the panel. Explicit retained-build selection is identified in the displayed provenance. Closed editors cancel their metadata worker.
 
-FXML parsing disables external entities and DOCTYPE. Inputs, scene-node counts, path expansion, target counts and protocol payloads are bounded. Ambiguous imports, duplicate IDs, missing classes, invalid XML and absent declarations produce diagnostics. Custom ViewModel selection, attached-property binding discovery, open child-draft metadata overlays, generated metadata precedence and complete collection compatibility remain later extensions, not silently inferred support.
+FXML parsing disables external entities and DOCTYPE. Inputs, scene-node counts, path expansion, target counts and protocol payloads are bounded. Ambiguous imports, duplicate IDs, missing classes, invalid XML and absent declarations produce diagnostics. Attached-property binding discovery, open child-draft metadata overlays, generated metadata precedence and complete collection compatibility remain later extensions, not silently inferred support.
 
 ## Qualification