p2: add quote and code-block text formatting

web/src/components/MessageComposer.tsx

@@ -872,6 +872,31 @@ export function MessageComposer() {
     });
   }
 
+  function insertQuoteBlock() {
+    const textarea = textareaRef.current;
+    if (!textarea) {
+      return;
+    }
+    const start = textarea.selectionStart ?? text.length;
+    const end = textarea.selectionEnd ?? text.length;
+    const selected = text.slice(start, end);
+    const source = selected || "quote";
+    const quoted = source
+      .split("\n")
+      .map((line) => `> ${line}`)
+      .join("\n");
+    const nextValue = `${text.slice(0, start)}${quoted}${text.slice(end)}`;
+    setText(nextValue);
+    if (activeChatId) {
+      setDraft(activeChatId, nextValue);
+    }
+    requestAnimationFrame(() => {
+      textarea.focus();
+      const pos = start + quoted.length;
+      textarea.setSelectionRange(pos, pos);
+    });
+  }
+
   return (
     <div className="border-t border-slate-700/50 bg-slate-900/55 p-3">
       {activeChatId && replyToByChat[activeChatId] ? (
@@ -950,6 +975,12 @@ export function MessageComposer() {
           <button className="rounded px-2 py-1 text-xs hover:bg-slate-800" onClick={() => insertFormatting("`", "`")} type="button" title="Monospace">
             M
           </button>
+          <button className="rounded px-2 py-1 text-xs hover:bg-slate-800" onClick={() => insertFormatting("```\n", "\n```", "code")} type="button" title="Code block">
+            {"</>"}
+          </button>
+          <button className="rounded px-2 py-1 text-xs hover:bg-slate-800" onClick={insertQuoteBlock} type="button" title="Quote">
+            ❝
+          </button>
           <button className="rounded px-2 py-1 text-xs hover:bg-slate-800" onClick={insertLink} type="button" title="Link">
             🔗
           </button>