[gl-agnx]

Fix

Answer unsupported SSH GLOBAL_REQUEST packets in the active Unix exec/PTY receive loop and the outer loop through one validated handler. OpenSSH keepalives receive REQUEST_FAILURE when want-reply is nonzero. No reply is sent for zero; malformed lengths and send failures fail closed. Authentication/key policy is unchanged.

Reproduction and evidence

• Actual KC705 port-22 daemon fails a read-only45-second quiet command with ServerAliveInterval10/ServerAliveCountMax3, exit255, empty stdout.
• Actual29.2MB staged-image hash takes75.50s, exposing the same timeout during seated-card software update. No boot-area mutation occurred.
• 110 actual-C parser/dispatch transport-stub fixtures pass; original source fails the missing-active-handler check.
• Complete Linux native CMake build and the registered server_init CTest pass.
• Yocto GCC15.3 SDK RV64IMAC/LP64 crosscompile passes; new ELF SHA25658e7d6099816eb413dec6649d74d1a7647b9f1443686d7c8b4d4cd5eec56c4c6.
• Real encrypted45-second live-output and output-EOF/exit9 smoke cases added to Linux CI. The VM lacks passwordless sudo for isolated-account smoke, so actual board temporary-daemon/physical qualification remains in progress. Keep draft until it passes.

All artifacts and reports are kept in the centralized kc705-mpunoxv workspace.