refactor: de-duplicate channel runtime and payload helpers

src/shared/tailscale-status.ts

@@ -0,0 +1,70 @@
+export type TailscaleStatusCommandResult = {
+  code: number | null;
+  stdout: string;
+};
+
+export type TailscaleStatusCommandRunner = (
+  argv: string[],
+  opts: { timeoutMs: number },
+) => Promise<TailscaleStatusCommandResult>;
+
+const TAILSCALE_STATUS_COMMAND_CANDIDATES = [
+  "tailscale",
+  "/Applications/Tailscale.app/Contents/MacOS/Tailscale",
+];
+
+function parsePossiblyNoisyJsonObject(raw: string): Record<string, unknown> {
+  const start = raw.indexOf("{");
+  const end = raw.lastIndexOf("}");
+  if (start === -1 || end <= start) {
+    return {};
+  }
+  try {
+    return JSON.parse(raw.slice(start, end + 1)) as Record<string, unknown>;
+  } catch {
+    return {};
+  }
+}
+
+function extractTailnetHostFromStatusJson(raw: string): string | null {
+  const parsed = parsePossiblyNoisyJsonObject(raw);
+  const self =
+    typeof parsed.Self === "object" && parsed.Self !== null
+      ? (parsed.Self as Record<string, unknown>)
+      : undefined;
+  const dns = typeof self?.DNSName === "string" ? self.DNSName : undefined;
+  if (dns && dns.length > 0) {
+    return dns.replace(/\.$/, "");
+  }
+  const ips = Array.isArray(self?.TailscaleIPs) ? (self.TailscaleIPs as string[]) : [];
+  return ips.length > 0 ? (ips[0] ?? null) : null;
+}
+
+export async function resolveTailnetHostWithRunner(
+  runCommandWithTimeout?: TailscaleStatusCommandRunner,
+): Promise<string | null> {
+  if (!runCommandWithTimeout) {
+    return null;
+  }
+  for (const candidate of TAILSCALE_STATUS_COMMAND_CANDIDATES) {
+    try {
+      const result = await runCommandWithTimeout([candidate, "status", "--json"], {
+        timeoutMs: 5000,
+      });
+      if (result.code !== 0) {
+        continue;
+      }
+      const raw = result.stdout.trim();
+      if (!raw) {
+        continue;
+      }
+      const host = extractTailnetHostFromStatusJson(raw);
+      if (host) {
+        return host;
+      }
+    } catch {
+      continue;
+    }
+  }
+  return null;
+}