docs(boundaries): add import-topology guardrails

src/plugin-sdk/AGENTS.md

@@ -26,6 +26,15 @@ can affect bundled plugins and third-party plugins.
 - Do not expose implementation convenience from `src/channels/**`,
   `src/agents/**`, `src/plugins/**`, or other internals unless you are
   intentionally promoting a supported public contract.
+- Keep public SDK entrypoints cheap at module load. If a helper is only needed
+  on async paths such as send, monitor, probe, directory-live, login, or setup,
+  prefer a narrow `*.runtime` subpath over re-exporting it through a broad SDK
+  barrel that hot channel entrypoints import on startup.
+- Keep SDK facades acyclic. Do not add back-edge re-exports that route a
+  lightweight contract file back through heavier policy or runtime modules.
+- Do not mix static and dynamic imports for the same runtime surface when
+  shaping SDK seams. If a surface must stay lazy, keep the eager side on a
+  light contract file and the deferred side on a dedicated runtime subpath.
 - Prefer `api.runtime` or a focused SDK facade over telling extensions to reach
   into host internals directly.
 - When core or tests need bundled plugin helpers, prefer the plugin package
@@ -33,6 +42,14 @@ can affect bundled plugins and third-party plugins.
   provider-named `src/plugin-sdk/<id>.ts` seam just to make core aware of a
   bundled channel's private helpers.
 
+## Verification
+
+- If you touch SDK seams that affect lazy loading, hot channel entrypoints, or
+  bundled plugin import topology, run `pnpm build`.
+- If the change can alter bundled channel startup cost, also run the isolated
+  entrypoint profiler for the affected plugin:
+  `OPENCLAW_LOCAL_CHECK=0 node scripts/profile-extension-memory.mjs --extension <id> --skip-combined --concurrency 1`
+
 ## Expanding The Boundary
 
 - Additive, backwards-compatible changes are the default.