refactor(channels): share route format and binding helpers

src/shared/text/auto-linked-file-ref.ts

@@ -0,0 +1,27 @@
+const FILE_REF_EXTENSIONS = ["md", "go", "py", "pl", "sh", "am", "at", "be", "cc"] as const;
+
+export const FILE_REF_EXTENSIONS_WITH_TLD = new Set<string>(FILE_REF_EXTENSIONS);
+
+export function isAutoLinkedFileRef(href: string, label: string): boolean {
+  const stripped = href.replace(/^https?:\/\//i, "");
+  if (stripped !== label) {
+    return false;
+  }
+  const dotIndex = label.lastIndexOf(".");
+  if (dotIndex < 1) {
+    return false;
+  }
+  const ext = label.slice(dotIndex + 1).toLowerCase();
+  if (!FILE_REF_EXTENSIONS_WITH_TLD.has(ext)) {
+    return false;
+  }
+  const segments = label.split("/");
+  if (segments.length > 1) {
+    for (let i = 0; i < segments.length - 1; i += 1) {
+      if (segments[i]?.includes(".")) {
+        return false;
+      }
+    }
+  }
+  return true;
+}