implemented compose by url, parse, local yaml.

README.md

@@ -257,6 +257,34 @@ instead of exposing individual host ports.
 See `host_vars/edge.yml.example`, `host_vars/downstream.yml.example`, and
 `docs/topology.md`. The full Docker service list is in `docs/service-catalog.md`.
 
+## Compose Updates
+
+Compose-backed roles deploy from role-owned Jinja templates, not directly from
+upstream examples. Upstream README and Compose examples are tracked as copied
+snapshots under each role's `upstream/` directory and indexed in
+`docs/upstream-sources.yml`.
+
+Use `compose_paths` for Compose files inside an upstream repository and
+`compose_urls` for direct raw HTTP Compose YAML fallbacks. Use role-level
+`local_compose_file` for Compose reference material already stored in this
+repository. README fenced Compose blocks are parsed when no explicit Compose
+file is available.
+
+Use `docs/compose-update-policy.md` when updating services so upstream drift,
+NBOPS overrides, image pins, and generated Compose files stay reviewable in Git.
+
+To test upstream references for one role:
+
+```sh
+scripts/vendor-upstream-snapshots.py jellyfin
+```
+
+To refresh copied upstream references:
+
+```sh
+scripts/vendor-upstream-snapshots.py --apply jellyfin
+```
+
 ## Bootstrap
 
 Render `templates/cloud-init-user-data.yml.j2` with host variables and pass it to