chore: sync the design document after the wrap change

src/docs/design.md

@@ -48,7 +48,7 @@ Remote servers over Streamable HTTP:
 }
 ```
 
-`agent-chaperone wrap <config>` makes that edit to a client configuration file you name. It prints what it would change and writes nothing until `--write`, and it keeps the original beside the file, because a client will not start without this file and a bad edit breaks every server at once. `--unwrap` takes it back out, and running either twice changes nothing.
+`agent-chaperone wrap <config>` makes that edit to a client configuration file you name. It prints what it would change and writes nothing until `--write`, and it keeps the original beside the file, because a client will not start without this file and a bad edit breaks every server at once. `--unwrap` takes it back out, and running either twice changes nothing. A remote entry is wrapped only when the proxy can carry everything it needs: one that declares a transport other than Streamable HTTP, or carries headers or auth of its own, is left alone and the output says why, because the client would stop sending those and the proxy would never receive them. `--header-env` passes a token to the proxy instead.
 
 Backend selection, in order: `TYPESAFE_API_KEY` (direct), `OPENROUTER_API_KEY` (the OpenRouter Decisions endpoint), `AI_GATEWAY_API_KEY` (Vercel AI Gateway). With no key present the proxy runs rules-only and logs one warning at startup. It never fails to start because a key is missing.