diff --git a/docker-compose.yml b/docker-compose.yml
index e720c3b..3d36a86 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -17,6 +17,11 @@ services:
       # Chat uploads / recordings / transcripts on the persistent volume too, so they survive image
       # rebuilds (otherwise old shared images 404 as "broken image" after every deploy).
       - UPLOADS_DIR=/data/uploads
+      # Max chat-attachment size in MB (default 1024 = 1 GB). The app streams uploads to /data/uploads, so
+      # large files don't buffer in memory. IMPORTANT: also set Nginx Proxy Manager's client_max_body_size
+      # for remote.bizgaze.com to at least this (Advanced tab: `client_max_body_size 1024m;`) or the proxy
+      # rejects big uploads before they reach the app.
+      - MAX_UPLOAD_MB=1024
       - REC_DIR=/data/recordings
       - TRANS_DIR=/data/transcripts
     # Secrets (TURN credentials, SSO_SECRET, BIZGAZE_WEBHOOK_URL, etc.) live in
diff --git a/server/public/home.html b/server/public/home.html
index fc3243e..6b4e684 100644
--- a/server/public/home.html
+++ b/server/public/home.html
@@ -1158,7 +1158,7 @@
 </head>
 <body>
 <script src="/icons.js?v=6"></script>
-<script>window.__BUILD='2026-07-20-batch144';console.log('%cBiz Connect','color:#1F3B73;font-weight:bold','build '+window.__BUILD);
+<script>window.__BUILD='2026-07-20-batch145';console.log('%cBiz Connect','color:#1F3B73;font-weight:bold','build '+window.__BUILD);
 // Emoji are rendered with the OS's own (colour) emoji font — instant, zero network.
 //
 // We used to run Twemoji over every emoji, which swapped each one for an <img> pulled INDIVIDUALLY from
@@ -2178,7 +2178,7 @@ function fmtSize(b){ b=+b||0; if(b<1024) return b+' B'; if(b<1048576) return Mat
 // (and a %), making it obvious when it's safe to hit Send.
 function uploadFile(file){
   if(!file) return;
-  if(file.size>25*1024*1024){ toast('“'+file.name+'” is too large (max 25 MB)'); return; }
+  if(file.size>1024*1024*1024){ toast('“'+file.name+'” is too large (max 1 GB)'); return; }
   const ph={ id:'up-'+Math.random().toString(36).slice(2), name:file.name, mime:file.type||'', uploading:true, pct:0, size:file.size };
   pendingAttachs.push(ph); renderAttachBar();
   const fail=(msg)=>{ const i=pendingAttachs.indexOf(ph); if(i>=0) pendingAttachs.splice(i,1); renderAttachBar(); toast(msg||'Upload failed'); };
diff --git a/server/routes.js b/server/routes.js
index 8b7f62a..edd1bd5 100644
--- a/server/routes.js
+++ b/server/routes.js
@@ -131,7 +131,8 @@ const mailer = require('./mailer');
 // Basic email validation for external meeting invitees (#4).
 const isEmail = (s) => typeof s === 'string' && /^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(s.trim());
 const crypto = require('crypto');
-const MAX_FILE_BYTES = 25 * 1024 * 1024; // 25 MB per chat attachment
+const MAX_UPLOAD_MB = parseInt(process.env.MAX_UPLOAD_MB, 10) || 1024; // default 1 GB per chat attachment
+const MAX_FILE_BYTES = MAX_UPLOAD_MB * 1024 * 1024; // NOTE: also raise Nginx Proxy Manager's client_max_body_size to match (default is 1 MB) or large uploads are rejected at the proxy before reaching here.
 
 // Mint a LiveKit access token (HS256 JWT signed with the API secret) — same hand-rolled JWT
 // approach as push.js's FCM/APNs tokens, so no extra dependency. Grants the holder join+publish+
@@ -1699,18 +1700,34 @@ route('POST', '/api/messages/upload', async (req, res) => {
   if (!u) return json(res, 401, { error: 'unauthorized' });
   const name = decodeURIComponent(req.headers['x-filename'] || 'file').slice(0, 200);
   const mime = (req.headers['content-type'] || 'application/octet-stream').split(';')[0].trim();
-  const chunks = []; let total = 0, aborted = false;
-  req.on('data', (c) => { total += c.length; if (total > MAX_FILE_BYTES) { aborted = true; req.destroy(); return; } chunks.push(c); });
-  req.on('end', () => {
-    if (aborted) return json(res, 413, { error: 'file too large (max 25 MB)' });
-    if (!total) return json(res, 400, { error: 'empty file' });
-    const id = A.id();
-    try { fs.writeFileSync(path.join(UPLOADS_DIR, id), Buffer.concat(chunks)); }
-    catch (e) { return json(res, 500, { error: 'could not store file' }); }
-    R.attachments.create({ id, teamId: u.team_id, uploaderId: u.id, name, mime, size: total });
-    json(res, 200, { id, name, mime, size: total });
+  // STREAM the body straight to disk (never buffer the whole file in memory — a 1 GB attachment would OOM the
+  // container). Write to a .part temp file, then atomically rename on success. Backpressure-aware so a fast
+  // uploader on a slow disk can't blow up memory either.
+  const id = A.id();
+  const tmp = path.join(UPLOADS_DIR, id + '.part');
+  let ws, total = 0, aborted = false, done = false;
+  try { ws = fs.createWriteStream(tmp); } catch (e) { return json(res, 500, { error: 'could not store file' }); }
+  const cleanup = () => { try { ws.destroy(); } catch (_) {} try { fs.unlinkSync(tmp); } catch (_) {} };
+  const finish = (code, body) => { if (done) return; done = true; json(res, code, body); };
+  ws.on('error', () => { aborted = true; cleanup(); finish(500, { error: 'could not store file' }); });
+  req.on('data', (c) => {
+    if (aborted) return;
+    total += c.length;
+    if (total > MAX_FILE_BYTES) { aborted = true; cleanup(); finish(413, { error: 'file too large (max ' + MAX_UPLOAD_MB + ' MB)' }); try { req.destroy(); } catch (_) {} return; }
+    if (!ws.write(c)) { req.pause(); ws.once('drain', () => { if (!aborted) req.resume(); }); } // respect backpressure
   });
-  req.on('error', () => { try { res.end(); } catch (e) {} });
+  req.on('end', () => {
+    if (aborted) return;
+    ws.end(() => {
+      if (!total) { try { fs.unlinkSync(tmp); } catch (_) {} return finish(400, { error: 'empty file' }); }
+      try { fs.renameSync(tmp, path.join(UPLOADS_DIR, id)); }
+      catch (e) { try { fs.unlinkSync(tmp); } catch (_) {} return finish(500, { error: 'could not store file' }); }
+      R.attachments.create({ id, teamId: u.team_id, uploaderId: u.id, name, mime, size: total });
+      finish(200, { id, name, mime, size: total });
+    });
+  });
+  req.on('error', () => { aborted = true; cleanup(); try { res.end(); } catch (e) {} });
+  req.on('aborted', () => { aborted = true; cleanup(); }); // client hung up mid-upload → drop the partial file
 });
 
 // API versioning: alias every /api/* route under /api/v1/* — a frozen contract for
