diff --git a/apps/server/src/services/auto_name.ts b/apps/server/src/services/auto_name.ts
index c1e43dd..341c60b 100644
--- a/apps/server/src/services/auto_name.ts
+++ b/apps/server/src/services/auto_name.ts
@@ -144,4 +144,23 @@ export async function maybeAutoNameChat(
     updated_at: updated[0]!.updated_at,
   });
   ctx.log.info({ chatId, name }, 'chat auto-named');
+
+  // Propagate to the parent session if it's still on its default name.
+  // The WHERE guard makes the check atomic — if the user has already
+  // renamed (or a prior chat already propagated), this UPDATE matches
+  // zero rows and we do nothing. First chat wins; manual renames win.
+  const renamedSession = await ctx.sql<{ id: string; name: string }[]>`
+    UPDATE sessions
+    SET name = ${name}
+    WHERE id = ${sessionId} AND name = 'New session'
+    RETURNING id, name
+  `;
+  if (renamedSession.length > 0) {
+    ctx.publishUser({
+      type: 'session_renamed',
+      session_id: sessionId,
+      name,
+    });
+    ctx.log.info({ sessionId, name }, 'session auto-named from chat');
+  }
 }