Revert "Studio: suppress RAG sources for uncited external prefetch"

This reverts commit 05944a1e9b.

studio/frontend/src/features/chat/api/chat-adapter.ts

@@ -449,18 +449,10 @@ function indexChunksByCitationId(
 function documentSourceIds(
   allChunks: ParsedChunk[],
   citedIds: Set<string>,
-  requireCitations: boolean,
 ): string[] {
   if (citedIds.size > 0) {
     return Array.from(citedIds);
   }
-  // Prefetch injects docs unconditionally, so zero citations means the model
-  // judged them irrelevant — emit no badges rather than falsely attributing an
-  // off-topic answer to every retrieved chunk. The tool path keeps the lenient
-  // fallback since the model itself chose to search.
-  if (requireCitations) {
-    return [];
-  }
   return allChunks.map((chunk) => chunk.id);
 }
 
@@ -511,10 +503,9 @@ function toDocumentSourcePart(
 function buildDocumentSourceParts(
   allChunks: ParsedChunk[],
   citedIds: Set<string>,
-  requireCitations: boolean,
 ): DocumentSourcePart[] {
   const byId = indexChunksByCitationId(allChunks);
-  const idsToShow = documentSourceIds(allChunks, citedIds, requireCitations);
+  const idsToShow = documentSourceIds(allChunks, citedIds);
   const out: DocumentSourcePart[] = [];
   const emittedIds = new Set<string>();
   for (const id of idsToShow) {
@@ -3136,31 +3127,14 @@ export function createOpenAIStreamAdapter(): ChatModelAdapter {
           }
           return parseChunks(typeof tc.result === "string" ? tc.result : "");
         });
-        const citedIds = extractCitedIds(cumulativeText);
         const documentSourceParts =
           ragChunks.length > 0
             ? buildDocumentSourceParts(
                 ragChunks,
-                citedIds,
-                // Prefetched (external) chunks were injected unconditionally,
-                // so require explicit citations before attributing sources.
-                ragPrefetchedThisTurn,
+                extractCitedIds(cumulativeText),
               )
             : [];
 
-        // Prefetch surfaces a synthetic search_knowledge_base card every turn.
-        // If the model cited none of the injected chunks it judged them
-        // irrelevant, so drop the card from the final (persisted) content —
-        // same rationale as the suppressed source badges above.
-        if (ragPrefetchSynthetic && citedIds.size === 0) {
-          const idx = toolCallParts.findIndex(
-            (p) => p.toolCallId === ragPrefetchSynthetic?.toolCallId,
-          );
-          if (idx !== -1) {
-            toolCallParts.splice(idx, 1);
-          }
-        }
-
         // SDK's SourceMessagePart only types `sourceType: "url"` with a
         // required `url` field. SourcesGroup branches on `sourceType` at
         // runtime, so cast the doc-shaped parts through `unknown` rather