Changes

• Subscribe TLS acceptors to the max handshake counter in Service::bind, so cached readiness is invalidated when the counter fills or frees a slot

• rustls: stop feeding an empty ciphertext buffer to the session after the input is drained, saving a read/process cycle per read and no longer signalling a false transport EOF to rustls

• openssl: join small write pages in a per-thread staging buffer instead of allocating 16 KiB for every joined record, unwritten bytes are kept for retry

• Defer peer-close shutdown until mutable TLS state and buffer borrows are released in all backends, preventing aliasing with inline read-task wakers

• schannel: scan fragmented handshake records without copying while a message is incomplete, and repack completed messages directly from the received records with a single copy

• schannel: borrow single-record handshake input during coalescing and SNI extraction, avoiding temporary payload copies while retaining fragmented handshake support and input limits

• schannel: support custom connectors returning filtered I/O, preserving the existing filter chain beneath TLS

• schannel: release opened CNG key handles when deleting a temporary private key fails, including certificate-setup rollback, and log cleanup failures

• schannel: reject empty plaintext handshake records and limit handshake reassembly to 64 KiB per message and 1024 records, preventing unbounded ciphertext buffering and repeated parsing while waiting for a message

• rustls: batch up to 32 queued plaintext pages per write without a gathering copy, reducing TLS records for many small pages while retaining partial writes