Use React to test render a few hardcoded posts, client and server side.
Render comments toolbar server side.
Cache the JS engine.
Use DefinitelyTyped's React typedefs.
Don't re-render React client side. Use real comments. Much more...

And:
- Make hover-actions work
- Send the current date-time to the client so markup won't change when
  calculating client side
- Include react-with-addons.js in render.js bundle
- Let dummy console functions actually log something
- Some more stuff...
Create one Nashorn engine per core.
Load React's page state from store.
Enable JMX, so can connect with VisualVM.
Missing import, log level.
Add new post by updating React's state. Break out class ReactJson.
Send back React JSON for Like and Wrong votes.
Add more action links in React.
Make Off-Topic and Wrong votes work again.
Send back React JSON for flags, make flagging work again.
Start creating render engines directly.
"Port" Close, Collapse, Delete to React.
Port edit replies to React. Simplify EditController.
Port edit history replies to React, make applying-edits work again.
Mark /-/load-page-parts as unused.
Render user data in browser only.