Remove legacy source provider sync path

README.md

@@ -4,27 +4,17 @@ A plugin-based DNS reconciliation service.
 
 ## Plugin contract
 
-Source modules live under `dns_sync/plugins/sources/` and export a class named `Plugin` with:
+The reconciliation runtime is adapter-based.
 
-- `name`
-- `discover() -> list[DesiredRecord]`
+Adapter plugins expose:
 
-Provider modules live under `dns_sync/plugins/providers/` and export `Plugin` with:
+- `Plugin`
+- `configured_endpoints(config)`
 
-- `name`
-- `capabilities`
-- `connect()`
-- `list_records()`
-- `add_record()`
-- `update_record()`
-- `delete_record()`
-- `verify_record()`
-- `capacity()`
-
-Plugins are convention-loaded from environment variables. No registry edit is needed:
-
-- `PROXY=npm` loads `dns_sync.plugins.sources.npm.Plugin`
-- `DNS_PROVIDER=verizon` loads `dns_sync.plugins.providers.verizon.Plugin`
+Each adapter declares object-specific discovery, apply, and verification
+capabilities. Built-in adapters live under `dns_sync/plugins/adapters/`.
+External adapters are loaded from `DNS_SYNC_PLUGIN_PATH` and must be
+explicitly enabled through `ENABLED_PLUGINS`.
 
 ## Plugins
 
@@ -109,8 +99,8 @@ ROUTER_PASSWORD=...
 
 ## Domain filtering
 
-Filtering is performed by the central engine after source discovery and before
-reconciliation, so all source plugins get identical behavior.
+Filtering is performed centrally after adapter discovery and before
+reconciliation, so endpoint-specific adapters get identical behavior.
 
 ```text
 DOMAIN_MATCHING=true