nx_tls13_p256_loopback_test.nx

nx_tls13_p256_loopback_test.nx -- server side of rung B4-P256-KEYSHARE: SOVEREIGN loopback proof that OUR server completes a TLS 1.3 key exchange on secp256r1. Found 2026-06-10 (B2 census): nishifamily.com -- our own server stack -- FAILED a P-256-only probe because recv_ch extracted x25519 shares only. This row proves the healed path end-to-end in-memory, no sockets: 1. client session emits a P-256-ONLY ClientHello (the same census mode the ch-compat github leg uses LIVE) 2. server recv_ch accepts it WITHOUT HelloRetryRequest (kex_group = 23, client share captured) 3. server emit_sh answers with a secp256r1 KeyShareEntry 4. client recv_sh completes its side (P-256 ECDH + schedule) 5. server derive_hs completes its side 6. THE PROOF: both sides hold byte-identical c/s handshake traffic secrets (only possible if both P-256 ECDH halves agree on the shared x-coordinate) 7. boundary: corrupted (off-curve) client share -> server derive_hs rejects with PROTOCOL_ERR, never INTERNAL Composes the github live leg (client vs independent peer) into a closed sovereign loop (our client vs OUR server). Deploying the healed server to nishifamily = follow-up (sites-daemon rebuild). expect_exit: 0 license_tier: ORIGINAL