pub fn open_m(held_roots: &[(u64, [u8; 32])], m_b64: &str) -> Option<Vec<u8>>Expand description
Try to open m under EVERY held server-root epoch key, newest first — absorbs both a
stale local head and a concurrent v1 refound that advanced past the publish root.
None = no held root opens it (caller decides: catch-up walk, then the straggler CTA).