CapySR/third_party/ikcp/README.md

ikcp (patched)

Upstream: https://github.com/skywind3000/kcp (public domain / MIT).

Star Rail uses a 28-byte KCP header instead of the stock 24: a 4-byte session token follows conv, both little-endian. The vendored copy is patched for it:

• IKCP_OVERHEAD 24 -> 28
• token field on IKCPSEG and IKCPCB
• ikcp_encode_seg / ikcp_input write and verify it
• ikcp_settoken(kcp, token) to set it after ikcp_create

Handshake packets carry conv/token as big-endian u32; the KCP header carries them little-endian. That byte reversal is what the real client expects.