CI: run global contract lane

.github/workflows/ci.yml

@@ -206,6 +206,9 @@ jobs:
           - runtime: node
             task: channels
             command: pnpm test:channels
+          - runtime: node
+            task: contracts
+            command: pnpm test:contracts
           - runtime: node
             task: protocol
             command: pnpm protocol:check

CONTRIBUTING.md

@@ -91,7 +91,9 @@ Welcome to the lobster tank! 🦞
 - Run tests: `pnpm build && pnpm check && pnpm test`
 - For extension/plugin changes, run the fast local lane first:
   - `pnpm test:extension <extension-name>`
-  - If you changed shared plugin or channel surfaces, still run the broader relevant lanes (`pnpm test:extensions`, `pnpm test:channels`, or `pnpm test`) before asking for review
+  - `pnpm test:extension --list` to see valid extension ids
+  - If you changed shared plugin or channel surfaces, run `pnpm test:contracts`
+  - If you changed broader runtime behavior, still run the relevant wider lanes (`pnpm test:extensions`, `pnpm test:channels`, or `pnpm test`) before asking for review
 - If you have access to Codex, run `codex review --base origin/main` locally before opening or updating your PR. Treat this as the current highest standard of AI review, even if GitHub Codex review also runs.
 - Ensure CI checks pass
 - Keep PRs focused (one thing per PR; do not mix unrelated concerns)