fn resolve_home() -> Option<PathBuf>Expand description
The true, unconditional ~/.agentmux root — MigrationContext.home.
Deliberately NOT derived from resolve_shared_store_path() (which
varies under isolated-auth mode, resolving to a channel-scoped path
instead of the global one) — nearly every registered migration builds
paths directly off ctx.home (registry/definitions/transcripts dirs),
and backup_stores/write_error_log below use it too. All of those
must stay anchored to the real global root regardless of isolation;
only ctx.shared_store_path itself is meant to vary. A single shared
helper (not one inline derivation per call site) so the two can’t
drift apart. See registry::resolve_global_shared_root’s doc comment
and docs/specs/SPEC_ISOLATED_AUTH_DEV_TESTING_2026_07_27.md.