feat: Session export as markdown in Diagnostic

- ⬇ Button per Session-Zeile — exportiert auch inaktive Sessions
- Server parst JSONL, extrahiert User/Assistant-Nachrichten mit Timestamp
- Metadata-Prefix wird entfernt, Markdown mit # Session-Header generiert
- Browser-Download via Blob + download-Attribut

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

diagnostic/server.js

@@ -1274,6 +1274,8 @@ wss.on("connection", (ws) => {
         handleListSessions(ws);
       } else if (msg.action === "read_session") {
         handleReadSession(ws, msg.sessionPath);
+      } else if (msg.action === "export_session") {
+        handleExportSession(ws, msg.sessionPath, msg.sessionKey);
       } else if (msg.action === "delete_session") {
         handleDeleteSession(ws, msg.sessionPath);
       } else if (msg.action === "set_active_session") {
@@ -1656,6 +1658,68 @@ async function handleReadSession(clientWs, sessionPath) {
   }
 }
 
+async function handleExportSession(clientWs, sessionPath, sessionKey) {
+  if (!sessionPath || sessionPath.includes("..") || !sessionPath.startsWith(SESSIONS_DIR)) {
+    clientWs.send(JSON.stringify({ type: "session_export", ok: false, error: "Ungueltiger Pfad" }));
+    return;
+  }
+  try {
+    const safePath = sessionPath.replace(/'/g, "");
+    const raw = await dockerExec("aria-core", `cat '${safePath}'`);
+    const lines = raw.split("\n").filter(l => l.trim());
+
+    const blocks = [];
+    for (const line of lines) {
+      let obj;
+      try { obj = JSON.parse(line); } catch { continue; }
+      if (obj.type !== "message" || !obj.message) continue;
+      const role = obj.message.role;
+      if (role !== "user" && role !== "assistant") continue;
+
+      let text = "";
+      const content = obj.message.content;
+      if (typeof content === "string") text = content;
+      else if (Array.isArray(content)) text = content.filter(c => c.type === "text").map(c => c.text || "").join("\n");
+      if (!text) continue;
+
+      if (role === "user") {
+        text = text.replace(/^Sender \(untrusted metadata\):[\s\S]*?```[\s\S]*?```\s*\n*/m, "").trim();
+        text = text.replace(/^\[.*?\]\s*/, "").trim();
+      } else {
+        text = text.replace(/^\[\[reply_to_\w+\]\]\s*/g, "").trim();
+      }
+      if (!text) continue;
+
+      const ts = obj.message.timestamp || obj.timestamp || 0;
+      const when = ts ? new Date(ts).toISOString().replace("T", " ").slice(0, 19) : "";
+      const heading = role === "user" ? "## 🧑 User" : "## 🤖 ARIA";
+      blocks.push(`${heading}${when ? ` — ${when}` : ""}\n\n${text}`);
+    }
+
+    const exportedAt = new Date().toISOString().replace("T", " ").slice(0, 19);
+    const title = sessionKey || sessionPath.split("/").pop().replace(".jsonl", "");
+    const markdown = [
+      `# Session: ${title}`,
+      ``,
+      `Exportiert: ${exportedAt}  `,
+      `Quelle: ${sessionPath}`,
+      ``,
+      `---`,
+      ``,
+      blocks.join("\n\n---\n\n"),
+      ``,
+    ].join("\n");
+
+    const safeKey = (sessionKey || "session").replace(/[^a-zA-Z0-9_-]/g, "_");
+    const filename = `${exportedAt.slice(0, 10)}_${safeKey}.md`;
+    clientWs.send(JSON.stringify({ type: "session_export", ok: true, filename, markdown }));
+    log("info", "server", `Session exportiert: ${filename} (${blocks.length} Nachrichten)`);
+  } catch (err) {
+    log("error", "server", `Session-Export fehlgeschlagen: ${err.message}`);
+    clientWs.send(JSON.stringify({ type: "session_export", ok: false, error: err.message }));
+  }
+}
+
 async function handleDeleteSession(clientWs, sessionPath) {
   if (!sessionPath || sessionPath.includes("..") || !sessionPath.startsWith(SESSIONS_DIR)) {
     clientWs.send(JSON.stringify({ type: "session_deleted", ok: false, error: "Ungueltiger Pfad" }));