diff --git a/pi-zulip-extension/src/index.ts b/pi-zulip-extension/src/index.ts
index 1492dfa..bf9f2af 100644
--- a/pi-zulip-extension/src/index.ts
+++ b/pi-zulip-extension/src/index.ts
@@ -590,8 +590,9 @@ export default function (pi: ExtensionAPI) {
         if (!pending || !pending.zulipMessageId) return;
 
         try {
-          const preview = streamingAccumulator.length > 1800
-            ? streamingAccumulator.slice(0, 1800) + "\n\n_… still generating…_"
+          const MAX_PREVIEW = 9500;
+          const preview = streamingAccumulator.length > MAX_PREVIEW
+            ? streamingAccumulator.slice(0, MAX_PREVIEW) + "\n\n_… still generating…_"
             : streamingAccumulator;
           await queue!.editMessage(pending.zulipMessageId, preview);
         } catch {
@@ -646,8 +647,9 @@ export default function (pi: ExtensionAPI) {
       return;
     }
 
-    const truncated = responseText.length > 1500
-      ? responseText.slice(0, 1500) + "\n\n[...truncated, see session for full output]"
+    const MAX_ZULIP_MSG = 10000;
+    const truncated = responseText.length > MAX_ZULIP_MSG
+      ? responseText.slice(0, MAX_ZULIP_MSG) + "\n\n[...truncated at Zulip limit, see session for full output]"
       : responseText;
 
     try {