Document D&D scene description artifacts

docs/internal/llm.md

@@ -39,7 +39,8 @@ without exposing Scriptorium types through stage contracts.
 7. injecting that one shared client into complete pipeline preparation before
    the source file is read or the runner is invoked.
 
-The D&D scene chunker and spell, NPC, and combat extractors retain this
+The D&D scene chunker and spell, NPC, combat-turn, NPC-interaction, and
+scene-description extractors retain this
 injected client and use it for every structured completion. Operation requests
 do not carry an LLM client.
 
@@ -98,7 +99,8 @@ D&D prompt content. `internal/framework/promptfs` provides the domain-neutral
 filesystem composition helper used to combine module-owned files with shared
 domain prompt fragments.
 
-The D&D scene chunker and spell, NPC, combat-turn, and NPC-interaction extractors each declare an
+The D&D scene chunker and spell, NPC, combat-turn, NPC-interaction, and
+scene-description extractors each declare an
 ordered prompt asset manifest. The manifest lists the package-owned YAML and
 Markdown files, then the exact shared fragments rendered by that prompt; the
 same ordered list drives both filesystem mounting and the prompt fingerprint.
@@ -132,7 +134,8 @@ prompt places its final boundary on its lane-specific instructions, immediately
 before the transcript. The transcript does not carry cache control because no
 reusable content follows it.
 
-Accordingly, the common prefix of all four extraction prompts is system,
+Accordingly, the common prefix of the spell, NPC, combat, and interaction
+extraction prompts is system,
 extraction evidence, identity, and campaign references. The NPC prompt then
 renders task, instructions, and transcript. Spell renders the NPC registry,
 catalog, task, instructions, and transcript. Combat renders the NPC registry,
@@ -142,6 +145,14 @@ scene chunker is not an extraction lane: it retains its separate system,
 transcript, campaign-reference, task, and instruction order and marks its
 transcript and campaign-reference messages ephemeral.
 
+The scene-description extractor deliberately omits the citation-oriented
+`common-dnd-extraction-evidence.md` asset because Notarius attaches the whole
+accepted chunk range itself. Its manifest is system, shared identity, shared
+campaign references, lane task, lane instructions, then the transcript. The
+identity, campaign-reference, and instruction messages are ephemeral cache
+boundaries; the transcript is last and has no cache control. Compatible shared
+messages remain canonical shared assets rather than copied package text.
+
 Shared wording belongs in the canonical assets under
 `internal/modules/dnd/shared`; extraction packages reference those assets in
 their manifests instead of copying similar text into package-local files.
@@ -155,7 +166,8 @@ return defensive copies, and expose a diagnostics map that omits schema bytes.
 The small framework registry contains only generic test schemas; production
 schemas remain package-owned.
 
-The spell, NPC, combat, and NPC-interaction extractors' package-owned prompts declare their
+The spell, NPC, combat, NPC-interaction, and scene-description extractors'
+package-owned prompts declare their
 structured JSON inputs and private response schemas. Each private response
 schema remains separate from its durable artifact codec schema; this work does
 not use shared schema fragments or schema generation. Those private schemas own