Consolidate scene and normalization prompt instructions

assets/dnd/scenes/prompts/instructions.md

@@ -1,8 +1,19 @@
-Cover the complete provided transcript from its first source unit to its last
-source unit. Return scenes in source-unit order with no gaps or overlaps. Use
-only positive integer source-unit IDs from the transcript, and give every scene
-one inclusive `start_unit_id` and one inclusive `end_unit_id`.
+Divide the complete provided transcript into coherent Dungeons & Dragons scenes
+for the `dnd/scenes` chunk module.
 
-Return exactly one JSON object and no explanatory text. The object must contain
-only a non-empty `scenes` array. Each scene object must contain only
-`start_unit_id` and `end_unit_id`.
+A scene is a coherent unit of play. Start a new scene when the transcript
+establishes a meaningful change in location, objective, threat, activity,
+encounter, or mode of play. Good reasons include a material move, beginning or
+ending combat, a substantially different encounter phase, a shift between
+combat, exploration, social interaction, planning, travel, rest, or downtime,
+a change in the central NPC, faction, threat, or objective, or a sustained
+table-level interruption that materially changes the activity.
+
+Do not split a scene merely because a speaker or combat round changes, a
+routine turn occurs, or the table briefly digresses. Prefer fewer coherent
+scenes over speculative or fine-grained boundaries.
+
+Cover the complete transcript from its first source unit to its last. Return
+scenes in source-unit order with no gaps or overlaps. Use only positive integer
+source-unit IDs from the transcript, and give every scene one inclusive
+`start_unit_id` and one inclusive `end_unit_id`.