fix: handle registration keys on headscale 0.29+

Closes HP-555.

app/server/headscale/api/capabilities.ts

@@ -36,6 +36,14 @@ export interface Capabilities {
    * 0.28.0+.
    */
   readonly nodeOwnerIsImmutable: boolean;
+
+  /**
+   * The `POST /api/v1/node/register` endpoint expects the full
+   * `hskey-authreq-<id>` AuthID as the `key` parameter. Pre-0.29
+   * Headscale expected the raw 24-character registration ID without
+   * the `hskey-authreq-` prefix. Introduced in 0.29.0.
+   */
+  readonly registerKeyIncludesAuthReqPrefix: boolean;
 }
 
 export function capabilitiesFor(version: ServerVersion): Capabilities {
@@ -43,5 +51,6 @@ export function capabilitiesFor(version: ServerVersion): Capabilities {
     preAuthKeysHaveStableIds: gte(version, "0.28.0"),
     nodeTagsAreFlat: gte(version, "0.28.0"),
     nodeOwnerIsImmutable: gte(version, "0.28.0"),
+    registerKeyIncludesAuthReqPrefix: gte(version, "0.29.0"),
   };
 }

app/server/headscale/api/resources/nodes.ts

@@ -62,14 +62,19 @@ export function makeNodeApi(
     register: async (user, key) => {
       // Headscale's node-register endpoint expects the registration
       // params as both query string and body — preserved as-is.
+      // Pre-0.29 expects the raw 24-char registration ID; 0.29+ expects
+      // the full `hskey-authreq-<id>` AuthID.
+      const registerKey = capabilities.registerKeyIncludesAuthReqPrefix
+        ? key
+        : key.replace(/^hskey-authreq-/, "");
       const qp = new URLSearchParams();
       qp.append("user", user);
-      qp.append("key", key);
+      qp.append("key", registerKey);
       const { node } = await transport.request<{ node: RawMachine }>({
         method: "POST",
         path: `v1/node/register?${qp.toString()}`,
         apiKey,
-        body: { user, key },
+        body: { user, key: registerKey },
       });
       return normalize(node);
     },