enforce close reason byte limit for websockets

[anonrig]

No description provided.

[ask-bonk]

Everything looks correct. Let me review the complete diff one more time carefully:

1. compatibility-date.capnp: New flag websocketCloseReasonByteLimit @164 with enable date 2026-03-03. Ordinal is sequential after @163. Has enable/disable flag names. Documentation is clear. All good.

2. web-socket.c++: The check is correctly gated behind the compat flag. Uses r.size() <= 123 which is correct for UTF-8 byte counting since kj::String stores UTF-8. Throws DOMSyntaxError which matches the WHATWG spec. Placement is correct — after code validation but before the "reason without code" check.

3. Test file: Good coverage — tests 124 ASCII bytes (should throw), exactly 123 bytes (should not throw), and multibyte characters (62 × 2 = 124 bytes, should throw). Tests properly clean up by calling ws.close() after the throwing case.

4. .wd-test: Correctly adds the compat flag to enable the new behavior for tests.

5. WPT test: Removes the expectedFailures entry for Close-Reason-124Bytes.any.js since the test should now pass. Adds a cleanup handler to close the WebSocket properly. This is well-reasoned — after close(1000, longReason) throws, the WebSocket remains in CONNECTING state and needs to be closed.

This is a clean, well-structured change. The compat flag is correctly used to gate the behavioral change. The implementation matches the spec. The tests are thorough. No issues found.

LGTM

github run