fix(upload): select the uploaded source by its own id

The chat selection was inferred by diffing the refreshed source list
against the snapshot taken before the upload, so any source that appeared
meanwhile -- another upload finishing, a new team share -- could be picked
instead. The upload response already carries the id; match on it, and
select nothing when it is absent rather than guessing.

Drops the now-unused sourceDocs read and its stale dependency.

frontend/src/upload/Upload.tsx

@@ -27,7 +27,6 @@ import { ActiveState, Doc } from '../models/misc';
 import { getDocs } from '../preferences/preferenceApi';
 import {
   selectSelectedDocs,
-  selectSourceDocs,
   selectToken,
   setSelectedDocs,
   setSourceDocs,
@@ -411,8 +410,6 @@ function Upload({
     heading: schema.heading,
   }));
 
-  const sourceDocs = useSelector(selectSourceDocs);
-
   const resetUploaderState = useCallback(() => {
     setIngestor({ type: null, name: '', config: {} });
     setfiles([]);
@@ -485,15 +482,11 @@ function Upload({
         if (status !== 'completed') return;
         refreshSourceDocs()
           .then((docs) => {
-            if (selectUploadedDoc && Array.isArray(docs)) {
-              const existingDocIds = new Set(
-                (Array.isArray(sourceDocs) ? sourceDocs : [])
-                  .map((doc: Doc) => doc?.id)
-                  .filter((id): id is string => Boolean(id)),
-              );
-              const newDoc = docs.find(
-                (doc: Doc) => doc.id && !existingDocIds.has(doc.id),
-              );
+            if (selectUploadedDoc && Array.isArray(docs) && sourceId) {
+              // Match the id this upload returned. Diffing against the list as
+              // it looked before would pick up any source that appeared
+              // meanwhile — another upload finishing, or a new team share.
+              const newDoc = docs.find((doc: Doc) => doc.id === sourceId);
               if (newDoc) {
                 // If only one doc is selected, replace it completely
                 // If multiple docs are selected, append the new doc
@@ -578,7 +571,6 @@ function Upload({
       refreshSourceDocs,
       selectedDocs,
       selectUploadedDoc,
-      sourceDocs,
       store,
     ],
   );