v3: chatbox improvements (typing indicators, answer to previous messages, backlog days separators, scroll to last message position, visual tweaks)

api/db/migrations/0009_chat_reply.ts

@@ -0,0 +1,17 @@
+import type { DatabaseSync } from "node:sqlite";
+
+// Adds an optional self-reference so a chat message can reply to another.
+// Kept as a plain column (no FK): when the replied-to message is later deleted
+// the id is retained but the join yields null, letting the UI show a subtle
+// "deleted message" reference instead of breaking the insert.
+//
+// Idempotent: also runs against fresh databases created from schema.sql, where
+// the column already exists.
+export function up(db: DatabaseSync): void {
+  const cols = db.prepare(`PRAGMA table_info(chat_messages);`).all() as {
+    name: string;
+  }[];
+  if (!cols.some((c) => c.name === "reply_to_id")) {
+    db.exec(`ALTER TABLE chat_messages ADD COLUMN reply_to_id TEXT;`);
+  }
+}