Clarify shared ownership of namespace views

engine.go

@@ -90,11 +90,12 @@ var (
 // [Engine.InspectRequirements], [Engine.InspectProfile], [Engine.Prepare], [Engine.PrepareExecution],
 // [Engine.Run], [Engine.RunPrepared], [Engine.SmokeTest], [Engine.ListProfiles],
 // [Engine.ListPrompts], [Engine.ListBackends], [Engine.ListNamespaces], and
-// [Engine.ListCollections]. Each Engine owns
+// [Engine.ListCollections]. Engines constructed separately by [NewEngine] own
 // independent backend-capacity pools that coordinate Run, RunPrepared, and
-// inference SmokeTest admission and model generation. Injected collaborators
-// may still be invoked concurrently across different backend pools or for
-// unlimited backends.
+// inference SmokeTest admission and model generation. Namespace views returned
+// by [Engine.WithNamespaces] share their underlying engine's pools, clients,
+// and prepared-execution owner. Injected collaborators may still be invoked
+// concurrently across different backend pools or for unlimited backends.
 type Engine struct {
 	internal *internalengine.Engine
 }
@@ -393,8 +394,9 @@ func (e *Engine) prepareRequest(ctx context.Context, req RunRequest) (*domain.Pr
 // configured LLMClient or reserving backend admission capacity. Validated
 // RunRequest.AppendedMessages are included in the frozen effective messages.
 //
-// The returned opaque handle is bound to this Engine and permits one
-// [Engine.RunPrepared] invocation. Preparation freezes the selected sources,
+// The returned opaque handle is bound to this Engine's underlying execution
+// owner, shared with its namespace views, and permits one [Engine.RunPrepared]
+// invocation in total. Preparation freezes the selected sources,
 // rendered messages, effective settings, inputs, provider structured-output
 // metadata, and validation resources needed by that invocation. The handle
 // retains a direct RunRequest.APIKey only in private execution state;
@@ -506,6 +508,11 @@ func (e *Engine) run(ctx context.Context, req RunRequest) (*RunResult, error) {
 // RunPrepared atomically claims and executes a handle created by
 // [Engine.PrepareExecution].
 //
+// The originating Engine and namespace views sharing its underlying owner may
+// claim the handle. Execution uses its captured selections without applying the
+// invoking view's namespaces. An Engine constructed separately by [NewEngine]
+// is a foreign owner.
+//
 // A valid owning-Engine invocation consumes the handle's one attempt before
 // credential revalidation, backend admission, generation, or validation.
 // Cancellation, capacity rejection, generation failure, operational