load_soul_md resolved the home ambiently, so a build thread that lost the
HERMES_HOME ContextVar read the launch profile's SOUL.md into another
profile's prompt — same class as the skills-index leak fixed in #86313.
load_soul_md and build_context_files_prompt now accept home_override, and
build_system_prompt_parts passes the agent's own home (from session_db)
at both SOUL call sites. Ambient behavior unchanged when no override.
Teknium