Fail invalid plugin registration gates loudly (#72577)

* fix plugin registration gate failures

docs/plugins/sdk-testing.md

@@ -81,6 +81,19 @@ describe("my-channel target resolution", () => {
 
 ## Testing patterns
 
+### Testing registration contracts
+
+Unit tests that pass a hand-written `api` mock to `register(api)` do not exercise
+OpenClaw's loader acceptance gates. Add at least one loader-backed smoke test
+for each registration surface your plugin depends on, especially hooks and
+exclusive capabilities such as memory.
+
+The real loader fails plugin registration when required metadata is missing or a
+plugin calls a capability API it does not own. For example,
+`api.registerHook(...)` requires a hook name, and
+`api.registerMemoryCapability(...)` requires the plugin manifest or exported
+entry to declare `kind: "memory"`.
+
 ### Unit testing a channel plugin
 
 ```typescript