Register D&D scene chunker

docs/internal/modules.md

@@ -59,6 +59,37 @@ Provides:
 
 - `chunks`
 
+## `dnd/scenes` Chunker
+
+Package: `internal/modules/chunk/dnd/scenes`
+
+The `dnd/scenes` chunker uses the structured LLM client to divide transcript
+source units into coherent D&D scenes. It renders embedded prompts, loads the
+embedded structured response schema, validates model-authored source-unit
+boundaries, and converts each scene into a deterministic source chunk.
+
+Requires:
+
+- `source.transcript`
+
+Provides:
+
+- `chunks`
+- `chunks.scenes`
+
+Options: none. Non-empty options are rejected.
+
+The chunker enforces full source-unit coverage from the first source unit to the
+last, exact source-unit IDs, sequential contiguous scenes, and no overlap. It
+assigns chunk IDs such as `scene-000001` and stores scene metadata including
+title, primary mode, participants, summary, boundary note, confidence, boundary
+unit IDs, and unit count. Boundary caveats become warnings with reason code
+`scene_boundary_caveat`.
+
+Malformed model output fails explicitly rather than falling back to another
+chunker. The chunker exposes prompt and response-schema provenance through its
+metadata provider without raw prompts, raw schemas, source text, or secrets.
+
 ## `dnd/spells` Extractor
 
 Package: `internal/modules/extract/dnd/spells`