diff --git a/server/src/simulation/save_io.rs b/server/src/simulation/save_io.rs
index 0f8644cba..895f4ac75 100644
--- a/server/src/simulation/save_io.rs
+++ b/server/src/simulation/save_io.rs
@@ -16,7 +16,7 @@ use thiserror::Error;
 
 use crate::bridge::types::SaveLoadResultWire;
 use crate::bridge::types::SnapshotBuffer;
-use crate::content::template::TemplateReferenceMap;
+use crate::content::template::{TemplateReferenceMap, TriangleState};
 use crate::knowledge::graph::KnowledgeGraph;
 use crate::knowledge::registry::EntityRegistry;
 use crate::npc::Npc;
@@ -113,6 +113,13 @@ pub fn save_to_file(path: &Path, world: &mut World) -> Result<(), SaveLoadError>
         .cloned()
         .unwrap_or_default();
 
+    // Capture TriangleState components — sorted by triangle_id for determinism (D-010).
+    let mut triangle_states: Vec<TriangleState> = {
+        let mut q = world.query::<&TriangleState>();
+        q.iter(world).cloned().collect()
+    };
+    triangle_states.sort_by_key(|t| t.triangle_id.0);
+
     let state = SaveStateV1 {
         format_version: SAVE_FORMAT_VERSION,
         tick,
@@ -122,6 +129,7 @@ pub fn save_to_file(path: &Path, world: &mut World) -> Result<(), SaveLoadError>
         relationship_graph,
         npc_states,
         template_references,
+        triangle_states,
     };
 
     let bytes = state
@@ -210,6 +218,11 @@ pub fn load_from_file(path: &Path, world: &mut World) -> Result<(), SaveLoadErro
     // Restore simulation resources.
     world.insert_resource(state.relationship_graph);
     world.insert_resource(state.template_references);
+
+    // Restore triangle states (#250) — spawn dedicated entities for each.
+    for ts in &state.triangle_states {
+        world.spawn(ts.clone());
+    }
     {
         let mut t = world.resource_mut::<SimulationTime>();
         t.tick = state.tick;
@@ -508,6 +521,7 @@ mod tests {
             relationship_graph: RelationshipGraph::new(),
             npc_states: vec![],
             template_references: TemplateReferenceMap::default(),
+            triangle_states: vec![],
         };
         let bytes = bad_state.to_bytes().expect("serialize");
         let path = temp_path();
diff --git a/server/src/simulation/save_state.rs b/server/src/simulation/save_state.rs
index 1a81f7a09..f6c24ef9c 100644
--- a/server/src/simulation/save_state.rs
+++ b/server/src/simulation/save_state.rs
@@ -39,7 +39,7 @@ use bevy_ecs::entity::Entity;
 use bevy_ecs::world::World;
 use serde::{Deserialize, Serialize};
 
-use crate::content::template::{TemplateOwnership, TemplateReferenceMap};
+use crate::content::template::{TemplateOwnership, TemplateReferenceMap, TriangleState};
 use crate::knowledge::graph::KnowledgeGraph;
 use crate::knowledge::registry::StableEntityId;
 use crate::knowledge::types::StableId;
@@ -89,6 +89,11 @@ pub struct SaveStateV1 {
     /// relationship metadata even when their NPCs are not in Active tier.
     #[serde(default)]
     pub template_references: TemplateReferenceMap,
+    /// Triangle escalation states (#250).
+    /// Persisted so tension/phase survive save/load. Sorted by triangle_id
+    /// for deterministic serialization (D-010).
+    #[serde(default)]
+    pub triangle_states: Vec<TriangleState>,
 }
 
 /// Per-NPC state snapshot for `SaveStateV1`.
@@ -399,6 +404,7 @@ mod tests {
             relationship_graph: RelationshipGraph::new(),
             npc_states: vec![],
             template_references: TemplateReferenceMap::default(),
+            triangle_states: vec![],
         }
     }
 
@@ -794,6 +800,7 @@ mod tests {
             relationship_graph: RelationshipGraph::new(),
             npc_states: vec![frozen],
             template_references: TemplateReferenceMap::default(),
+            triangle_states: vec![],
         };
 
         let bytes = save.to_bytes().expect("serialize");
diff --git a/server/tests/information_boundaries.rs b/server/tests/information_boundaries.rs
index 98be2a175..67e8f273b 100644
--- a/server/tests/information_boundaries.rs
+++ b/server/tests/information_boundaries.rs
@@ -204,6 +204,7 @@ fn save_state_npc_kg_isolation() {
         relationship_graph: RelationshipGraph::new(),
         npc_states: vec![npc_a_state, npc_b_state],
         template_references: Default::default(),
+        triangle_states: vec![],
     };
 
     // Roundtrip: serialize → deserialize.