Constant META_KEY_PTYSHELL_GH_CONFIG_DIR 

pub const META_KEY_PTYSHELL_GH_CONFIG_DIR: &str = "ptyshell:ghconfigdir";

Block meta on an agent’s PtyShell: the agent’s guard directory, which the PTY spawn sets as GH_CONFIG_DIR (blockcontroller::shell::lifecycle). A PTY shell’s env is built from its own block, not from the agent’s, so the guard has to travel on that block.