feat(core-realtime): channel-template matcher (placeholder extraction)

packages/core-realtime/src/channel-template.ts

@@ -0,0 +1,28 @@
+const PLACEHOLDER = /\{([a-zA-Z_][a-zA-Z0-9_]*)\}/g;
+
+export function matchChannelTemplate(
+  template: string,
+  candidate: string,
+): { params: Record<string, string> } | null {
+  // No placeholders: exact match.
+  if (!template.includes("{")) {
+    return template === candidate ? { params: {} } : null;
+  }
+
+  // Build a regex from the template, replacing {name} with named groups.
+  const names: string[] = [];
+  const escaped = template.replace(/[.+?^${}()|[\]\\]/g, "\\$&"); // escape regex specials
+  // The above escapes `{` and `}` too — restore them around placeholders.
+  const pattern = escaped.replace(/\\\{([a-zA-Z_][a-zA-Z0-9_]*)\\\}/g, (_m, name) => {
+    names.push(name);
+    return `([^.]+)`;
+  });
+  const re = new RegExp(`^${pattern}$`);
+  const match = candidate.match(re);
+  if (!match) return null;
+  const params: Record<string, string> = {};
+  names.forEach((name, i) => {
+    params[name] = match[i + 1]!;
+  });
+  return { params };
+}