A small fictional module from an invented publisher proves the union mount's multi-layer story end to end: four rules entries (two monsters, a spell, a magic item) and four lore entries (a village, a person, a faction, a legend), cross-linked with wikilinks that also reach into the SRD layer. knowledge::SESSION_LAYERS now names the ordered layer list a play session mounts, SRD first, and play::run takes the list while srd verify keeps the SRD root alone. tests/layers.rs opens the real session layers and fails if any wikilink in the module stops resolving. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01CUXjWo1zGFhdJUig1hcQGf