feat(chat): save a single answer as PDF via the print dialog

Hides app chrome via a 'printing-answer' class on body, leaves only the
.print-target visible. The class is removed in a finally so a cancelled
print dialog can't leave the app invisible.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/app/dashboard/chat/chat-view.tsx

@@ -32,6 +32,21 @@ export function ChatView() {
   const bottomRef = React.useRef<HTMLDivElement>(null);
   const inputRef = React.useRef<HTMLTextAreaElement>(null);
 
+  /** Print one answer. The class is removed in a finally so a cancelled
+      print dialog cannot leave the app invisible. */
+  const printAnswer = React.useCallback((index: number) => {
+    const el = document.getElementById(`answer-${index}`);
+    if (!el) return;
+    el.classList.add("print-target");
+    document.body.classList.add("printing-answer");
+    try {
+      window.print();
+    } finally {
+      document.body.classList.remove("printing-answer");
+      el.classList.remove("print-target");
+    }
+  }, []);
+
   // Pending photos attached to the next user turn. Declared before any
   // handler that reads it; useCallback closes over this state at the
   // time the handler is created, so the state must be in scope by then.
@@ -337,7 +352,7 @@ export function ChatView() {
             }
 
             return (
-              <div key={i} className="border-l-2 border-[#F2B165]/40 pl-4">
+              <div key={i} id={`answer-${i}`} className="border-l-2 border-[#F2B165]/40 pl-4">
                 {t.text ? (
                   <AnswerMarkdown>{t.text}</AnswerMarkdown>
                 ) : (
@@ -364,6 +379,12 @@ export function ChatView() {
                         {toolLabel(name)}
                       </span>
                     ))}
+                    <button
+                      onClick={() => printAnswer(i)}
+                      className="print-hide ml-auto rounded-full border border-border px-2 py-0.5 text-[11px] text-muted-foreground transition-colors hover:border-[#F2B165]/50 hover:text-foreground"
+                    >
+                      Save as PDF
+                    </button>
                   </div>
                 )}
               </div>

src/app/globals.css

@@ -216,3 +216,31 @@
     background-size: 32px 32px;
   }
 }
+
+/* Printing an answer: hide the app chrome and let the answer fill the page. Triggered by adding .printing-answer to <body>. */
+@media print {
+  body.printing-answer * {
+    visibility: hidden;
+  }
+  body.printing-answer .print-target,
+  body.printing-answer .print-target * {
+    visibility: visible;
+  }
+  body.printing-answer .print-target {
+    position: absolute;
+    inset: 0;
+    padding: 0;
+    border: 0;
+    max-width: none;
+  }
+  body.printing-answer .print-hide {
+    display: none !important;
+  }
+  /* Keep table rows intact across page breaks. */
+  body.printing-answer table {
+    page-break-inside: auto;
+  }
+  body.printing-answer tr {
+    page-break-inside: avoid;
+  }
+}