diff --git a/chat-core.js b/chat-core.js
index 5bea25a..d0547ce 100644
--- a/chat-core.js
+++ b/chat-core.js
@@ -15,11 +15,11 @@ async function apiFetch(url, options = {}, { timeoutMs = 45000 } = {}) {
 }
 window.apiFetch = apiFetch;
 
-// Load global AI instructions from external text file
-window.aiInstructions = "";
-window.aiInstructionPromise = fetch("ai-instruct.txt")
-    .then(res => res.text())
-    .then(text => { window.aiInstructions = text; })
+// Load global AI instructions from external markdown file
+window.aiInstructions = "";
+window.aiInstructionPromise = fetch("ai-instruct.md")
+    .then(res => res.text())
+    .then(text => { window.aiInstructions = text; })
     .catch(err => {
         console.error("Failed to load AI instructions", err);
         window.aiInstructions = "";
@@ -464,13 +464,13 @@ document.addEventListener("DOMContentLoaded", () => {
         chatBox.scrollTop = chatBox.scrollHeight;
 
         if (!window.aiInstructions) {
-            try {
-                const res = await fetch("ai-instruct.txt", { cache: "no-store" });
-                window.aiInstructions = await res.text();
-            } catch (e) {
-                window.aiInstructions = "";
-            }
-        }
+            try {
+                const res = await fetch("ai-instruct.md", { cache: "no-store" });
+                window.aiInstructions = await res.text();
+            } catch (e) {
+                window.aiInstructions = "";
+            }
+        }
 
         const messages = [];
         if (window.aiInstructions) {