Make local graph execution optional across composed packages

test/fixtures/local-first-reader/CommentData.qx

@@ -20,8 +20,8 @@ interface CommentData id "interface:reader:comment-data"
 revision "interface:reader:comment-data@1" {
   queryable value content id "comment:content" : CommentContent {
     get id "comment:content:get"
-    execution snapshot targets [browser, server];
+    execution snapshot;
     edit id "comment:content:edit"
-    execution transaction targets [browser, server];
+    execution transaction;
   }
 }

test/fixtures/local-first-reader/DocumentActions.qx

@@ -20,6 +20,6 @@ interface DocumentActions id "interface:reader:document-actions"
 revision "interface:reader:document-actions@1" {
   operation annotate id "document:annotate" : SourceRange -> atom-ref<Highlight> {
     call id "document:annotate:call"
-    execution transaction targets [browser, server];
+    execution transaction;
   }
 }

test/fixtures/local-first-reader/DocumentData.qx

@@ -20,17 +20,17 @@ interface DocumentData id "interface:reader:document-data"
 revision "interface:reader:document-data@1" {
   queryable value sourceRevision id "document:source-revision" : string {
     get id "document:source-revision:get"
-    execution snapshot targets [browser, server];
+    execution snapshot;
   }
   queryable value content id "document:content" : string {
     get id "document:content:get"
-    execution snapshot targets [browser, server];
+    execution snapshot;
   }
   queryable relation highlights id "document:highlights"
   : many-unique atom Highlight {
     resolve id "document:highlights:resolve"
-    execution snapshot targets [browser, server];
+    execution snapshot;
     connect id "document:highlights:connect"
-    execution transaction targets [browser, server];
+    execution transaction;
   }
 }

test/fixtures/local-first-reader/DocumentFactory.qx

@@ -20,6 +20,6 @@ interface DocumentFactory id "interface:reader:document-factory"
 revision "interface:reader:document-factory@1" {
   static operation create id "document:create" : DocumentSeed -> atom-ref<Document> {
     call id "document:create:call"
-    execution transaction targets [browser, server];
+    execution transaction;
   }
 }

test/fixtures/local-first-reader/HighlightData.qx

@@ -20,20 +20,20 @@ interface HighlightData id "interface:reader:highlight-data"
 revision "interface:reader:highlight-data@1" {
   queryable value range id "highlight:range" : SourceRange {
     get id "highlight:range:get"
-    execution snapshot targets [browser, server];
+    execution snapshot;
   }
   queryable value color id "highlight:color" : string {
     get id "highlight:color:get"
-    execution snapshot targets [browser, server];
+    execution snapshot;
     set id "highlight:color:set"
-    execution transaction targets [browser, server];
+    execution transaction;
   }
   queryable portable value excerpt id "highlight:excerpt" : string {
     get id "highlight:excerpt:get"
-    execution snapshot targets [browser, server];
+    execution snapshot;
   }
   queryable relation comments id "highlight:comments" : many-unique atom Comment {
     resolve id "highlight:comments:resolve"
-    execution snapshot targets [browser, server];
+    execution snapshot;
   }
 }

test/fixtures/local-first-reader/ReaderRuntime.qx

@@ -1,3 +1,4 @@
+symbol JavaScript id "target:org.quixos.execution.javascript@1";
 // Shared record definitions, repeated explicitly in independently locked resources.
 external atom Document id "atom:reader:document";
 external atom Highlight id "atom:reader:highlight";
@@ -29,7 +30,7 @@ package ReaderRuntime id "package:reader-runtime"
 revision "package:reader-runtime@1" {
   operation addHighlight id "reader:add-highlight"
   : SourceRange -> atom-ref<Highlight>
-  mode call execution transaction targets [browser, server]
+  mode call execution transaction targets [JavaScript, server]
   receiver atom Document requires {
     interface document id "reader:add:document" : DocumentData
     using [sourceRevision.get, content.get, highlights.connect];
@@ -38,7 +39,7 @@ revision "package:reader-runtime@1" {
   };
 
   operation excerpt id "reader:excerpt" : unit -> string
-  mode call execution snapshot targets [browser, server]
+  mode call execution snapshot targets [JavaScript, server]
   receiver atom Highlight requires {
     state range id "reader:excerpt:range" : SourceRange [read];
     interface document id "reader:excerpt:document" : DocumentData
@@ -48,11 +49,11 @@ revision "package:reader-runtime@1" {
   // A receiverless function needs no synthetic service object.
   function validateRange id "reader:validate-range"
   : record { range: SourceRange; content: string; } -> bool
-  execution snapshot targets [browser, server];
+  execution snapshot targets [JavaScript, server];
 
   function createDocument id "reader:create-document"
   : DocumentSeed -> atom-ref<Document>
-  execution transaction targets [browser, server] requires {
+  execution transaction targets [JavaScript, server] requires {
     creation document id "reader:create:document" : Document input DocumentSeed;
   };
   query ReplicaInputs id "reader:replica-inputs" root DocumentData