Add bots files handling logic

src/utils/file-ref.ts

@@ -0,0 +1,24 @@
+/**
+ * How a bot names one of its files in a message: `[file:12]`. The chat
+ * turns it into a link to the file (`linkComputerRefs`), which a chip
+ * renders with the file's name.
+ */
+export default function fileRef({ id }: { id: number | string }) {
+    return `[file:${id}]`;
+}
+
+/**
+ * The link target a file ref becomes, e.g. `#file-12`.
+ */
+export const FileRefHrefPrefix = "#file-";
+
+/**
+ * The id in a file ref's link target, or null.
+ */
+export function fileRefId({ href }: { href?: string | null }) {
+    if (!href?.startsWith(FileRefHrefPrefix)) return null;
+
+    const id = Number(href.slice(FileRefHrefPrefix.length));
+
+    return Number.isFinite(id) && id > 0 ? id : null;
+}