update CLAUDE.md

CLAUDE.md

@@ -210,6 +210,14 @@ Built-in JavaScript modules use special syntax and are organized as:
 
 Note: These are NOT ES modules. The preprocessor converts `$` to `@` (JSC's actual syntax) and handles the special functions.
 
+## CI
+
+Bun uses BuildKite for CI. To get the status of a PR, you can use the following command:
+
+```bash
+bun ci
+```
+
 ## Important Development Notes
 
 1. **Never use `bun test` or `bun <file>` directly** - always use `bun bd test` or `bun bd <command>`. `bun bd` compiles & runs the debug build.

test/CLAUDE.md

@@ -18,6 +18,8 @@ Note that compiling Bun may take up to 2.5 minutes. It is slow!
 
 Use `bun:test` with files that end in `*.test.ts`.
 
+**Do not write flaky tests**. Unless explicitly asked, **never wait for time to pass in tests**. Always wait for the condition to be met instead of waiting for an arbitrary amount of time. **Never use hardcoded port numbers**. Always use `port: 0` to get a random port.
+
 ### Spawning processes
 
 #### Spawning Bun in tests