feat(simulation): persist template ownership and references in save state

Adds TemplateOwnership to NpcSaveState and TemplateReferenceMap to
SaveStateV1 so cross-template links survive save/load and tier
eviction (D-025, D-026). Both fields use serde(default) for backward
compatibility with existing saves.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/simulation/save_state.rs

@@ -39,6 +39,7 @@ use bevy_ecs::entity::Entity;
 use bevy_ecs::world::World;
 use serde::{Deserialize, Serialize};
 
+use crate::content::template::{TemplateOwnership, TemplateReferenceMap};
 use crate::knowledge::graph::KnowledgeGraph;
 use crate::knowledge::registry::StableEntityId;
 use crate::knowledge::types::StableId;
@@ -83,6 +84,11 @@ pub struct SaveStateV1 {
     /// Per-NPC summary state for each simulated NPC.
     /// Order is deterministic (sorted by stable_id in ascending order).
     pub npc_states: Vec<NpcSaveState>,
+    /// Cross-template reference links (#165).
+    /// Preserved across save/load so that tier-evicted templates retain their
+    /// relationship metadata even when their NPCs are not in Active tier.
+    #[serde(default)]
+    pub template_references: TemplateReferenceMap,
 }
 
 /// Per-NPC state snapshot for `SaveStateV1`.
@@ -184,6 +190,12 @@ pub struct NpcSaveState {
     /// Job performance score — drifts over time, persist across tier transitions.
     #[serde(default)]
     pub job_performance: Option<JobPerformance>,
+
+    /// Template ownership (#165): which template owns this NPC and which role it fills.
+    /// `None` for NPCs that predate the template system or were hand-authored without
+    /// template assignment. Preserved across tier transitions (D-025 single-ownership).
+    #[serde(default)]
+    pub template_ownership: Option<TemplateOwnership>,
 }
 
 impl SaveStateV1 {
@@ -258,6 +270,7 @@ pub fn serialize_npc_to_frozen(entity: Entity, world: &World) -> NpcSaveState {
         combat_capability: world.get::<CombatCapability>(entity).cloned(),
         mood_state: world.get::<MoodState>(entity).cloned(),
         job_performance: world.get::<JobPerformance>(entity).cloned(),
+        template_ownership: world.get::<TemplateOwnership>(entity).cloned(),
     }
 }
 
@@ -353,6 +366,10 @@ pub fn deserialize_npc_from_frozen(state: &NpcSaveState, world: &mut World) -> E
         if let Some(combat) = state.combat_capability.clone() {
             em.insert(combat);
         }
+        // Restore template ownership if present — never reassigned after initial spawn (D-025).
+        if let Some(ownership) = state.template_ownership.clone() {
+            em.insert(ownership);
+        }
     }
 
     entity
@@ -381,6 +398,7 @@ mod tests {
             player_knowledge: KnowledgeGraph::new(),
             relationship_graph: RelationshipGraph::new(),
             npc_states: vec![],
+            template_references: TemplateReferenceMap::default(),
         }
     }
 
@@ -449,6 +467,7 @@ mod tests {
                 combat_capability: None,
                 mood_state: None,
                 job_performance: None,
+                template_ownership: None,
             },
             NpcSaveState {
                 stable_id: StableId(202),
@@ -469,6 +488,7 @@ mod tests {
                 combat_capability: None,
                 mood_state: None,
                 job_performance: None,
+                template_ownership: None,
             },
         ];
 
@@ -577,6 +597,7 @@ mod tests {
             combat_capability: None,
             mood_state: None,
             job_performance: None,
+            template_ownership: None,
         }];
 
         let bytes = state.to_bytes().expect("serialize");
@@ -734,6 +755,7 @@ mod tests {
             combat_capability: None,
             mood_state: None,
             job_performance: None,
+            template_ownership: None,
         };
 
         let mut world = World::new();
@@ -771,6 +793,7 @@ mod tests {
             player_knowledge: KnowledgeGraph::new(),
             relationship_graph: RelationshipGraph::new(),
             npc_states: vec![frozen],
+            template_references: TemplateReferenceMap::default(),
         };
 
         let bytes = save.to_bytes().expect("serialize");