🔵 [Low] Test verifies the counter but not the end-to-end chain-send behavior it fixes

The new test directly asserts ssl->buffers.certChainCnt increments per chain cert, which is a good, targeted regression guard for this specific fix. It does not, however, exercise the actual symptom (a TLS 1.3 handshake emitting a full chain rather than a leaf-only Certificate message), nor the wolfSSL_add1_chain_cert path which funnels through wolfSSL_add0_chain_cert and is therefore also affected by the fix. The unit test is acceptable as-is given how much harder a full handshake assertion would be, but coverage of the add1 wrapper would be cheap and worthwhile. Also note: if SSL_add0_chain_cert ever returned 0 inside the loop, the just-loaded x509 would leak since it is unconditionally set to NULL afterward without being freed on the failure path -- only a concern under a future regression, not current behavior.

Fix: Consider adding a parallel assertion via SSL_add1_chain_cert (verifying both the count increments and the X509 ref count is bumped), and/or a comment noting the unit test stands in for the harder-to-author TLS 1.3 full-chain handshake check.

⚪ [Info] Increment is unconditional while CTX equivalent guards it with WOLFSSL_TLS13

The new ssl->buffers.certChainCnt++; is unconditional, whereas the analogous CTX helper wolfssl_ctx_add_to_chain (src/ssl_load.c:4968-4971) wraps ctx->certChainCnt++; in #ifdef WOLFSSL_TLS13. This is a minor stylistic inconsistency, not a bug: the certChainCnt member is always defined (under #ifndef NO_CERTS, wolfssl/internal.h:5029), so the unconditional increment always compiles, and the count is consumed both by TLS 1.3 (SendTls13Certificate) and by the non-TLS1.3 OCSP-multi path (MIN(cnt, certChainCnt + 1) at src/internal.c:26269). The unconditional form here is arguably more correct than the CTX version because it keeps the count accurate even in non-TLS1.3 builds. No change required; flagging only for awareness of the divergence between the two helpers.

Fix: Leave as-is (unconditional is fine and slightly more correct). Optionally note the divergence, or align the CTX helper to also increment unconditionally in a follow-up for consistency.