Add feature roadmap and implementation plan for D&D spell extraction and validation upgrades

docs/internal/modules.md

@@ -50,6 +50,23 @@ Reference material may inform a module or prompt but must not become source
 evidence. The resolver and materializer behavior is described in
 [Pipeline Internals](pipeline.md#reference-materialization).
 
+## Domain Reference Data
+
+### `internal/modules/dnd/spells/catalog`
+
+The spell catalog package owns the embedded, versioned D&D 5e 2014 SRD spell
+reference data. Its strict JSON asset contains one canonical record per spell,
+including spell level and all applicable class memberships. `LoadSRD5E2014`
+validates catalog identity, provenance metadata, ordering, uniqueness, levels,
+classes, aliases, and lookup-key collisions before exposing immutable copies.
+
+Lookup is case-insensitive and normalizes whitespace and common apostrophe
+variants while preserving source punctuation in canonical display names. The
+catalog contains 319 unique spells and 779 class memberships. Source and
+license details live beside the asset in `SOURCES.md`. This domain-owned data is
+separate from `internal/modules/dnd/shared`, which is reserved for reusable
+prompt and source-reference machinery.
+
 ## Input Adapter
 
 ### `internal/modules/seriatim/input/transcript`