Open Brain documents from their title

Clicking a document's title fetches the original file from the engine:
viewable formats open in a new tab, the rest (or a blocked tab) download
under the original name.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/pages/Brain.tsx

@@ -1,7 +1,7 @@
 import { useEffect, useRef, useState, type ReactNode } from 'react'
 import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query'
 import {
-  answerVersion, buildKnowledge, deleteDocument, knowledgeDetail, listDocuments, NEEDS_ANSWER, supportedExtensions, uploadDocument,
+  answerVersion, buildKnowledge, deleteDocument, documentFile, knowledgeDetail, listDocuments, NEEDS_ANSWER, supportedExtensions, uploadDocument,
   type Source,
 } from '../api/engine'
 import { Icon } from '../components/Icon'
@@ -154,7 +154,7 @@ function DocumentRow({ doc }: { doc: Source }) {
     <div className="result-row">
       <span className={`file-icon ${doc.format.toLowerCase()}`}>{doc.format.slice(0, 4)}</span>
       <div style={{ minWidth: 0, flex: 1 }}>
-        <b>{doc.title}</b>
+        <OpenButton doc={doc} />
         <div><small>{new Date(doc.createdAt).toLocaleDateString(locale())}</small></div>
         {phase === 'working' && <Progress doc={doc} />}
         {(phase === 'answer' || phase === 'failed') && <KnowledgeAction doc={doc} />}
@@ -165,6 +165,36 @@ function DocumentRow({ doc }: { doc: Source }) {
   )
 }
 
+// Formats a browser can show in a tab; anything else is saved under its original name.
+const VIEWABLE = new Set(['pdf', 'png', 'jpg', 'jpeg', 'gif', 'webp', 'svg', 'txt', 'md', 'csv', 'mp3', 'wav', 'm4a', 'ogg', 'mp4', 'webm', 'mov'])
+
+function OpenButton({ doc }: { doc: Source }) {
+  const [busy, setBusy] = useState(false)
+  async function open() {
+    const inTab = VIEWABLE.has(doc.format.toLowerCase())
+    // Opened before the fetch: a tab opened after an await counts as a popup and is blocked.
+    const tab = inTab ? window.open('', '_blank') : null
+    setBusy(true)
+    try {
+      const url = URL.createObjectURL(await documentFile(doc.docId))
+      if (tab) tab.location.href = url
+      // Not viewable, or the tab was blocked: save it instead of doing nothing.
+      else Object.assign(document.createElement('a'), { href: url, download: doc.originalName }).click()
+      setTimeout(() => URL.revokeObjectURL(url), 60_000)
+    } catch (e) {
+      tab?.close()
+      toast((e as Error).message, { error: true })
+    } finally {
+      setBusy(false)
+    }
+  }
+  return (
+    <button className="doc-title" disabled={busy} title={t('brain.open', { name: doc.originalName })} onClick={open}>
+      {doc.title}
+    </button>
+  )
+}
+
 function StatusBadge({ doc, phase }: { doc: Source; phase: Phase }) {
   const label = {
     ready: t('brain.statusReady'),