feat:lineage compat, nessa made more similar

src/routes/api/lineage/offline_secret.ts

@@ -0,0 +1,22 @@
+// Plain-text route for the Lineage offline secret.
+//
+// `misc.offlineSecret` is a tRPC `.query()` returning `{ secret: "…" }`. But
+// the Lineage client's `IAPStore.fetchOfflineSecret` does
+// `await response.text()` and uses the raw string directly as the decryption
+// key. trpc-openapi always JSON-encodes responses, so exposing it via the openapi
+// shim would yield `'{"secret":"…"}'` as text and break decryption.
+//
+// This dedicated route returns the secret verbatim as `text/plain`, matching
+// exactly what the legacy endpoint returned. Auth: none (the legacy endpoint
+// had none either — the secret is a server-side decryption key shared to all
+// clients; it rotates with `LINEAGE_OFFLINE_SERIALIZATION_SECRET`).
+
+import type { APIEvent } from "@solidjs/start/server";
+import { env } from "~/env/server";
+
+export const GET = (event: APIEvent) => {
+  return new Response(env.LINEAGE_OFFLINE_SERIALIZATION_SECRET, {
+    status: 200,
+    headers: { "content-type": "text/plain; charset=utf-8" }
+  });
+};