fix(simulation): fix triangle state save/load and persist contamination

Three save/load bugs fixed:
- ContaminationActive not persisted in SaveStateV1 — caused double-fire
  of contamination pressure on reload after tick 300.
- Loaded triangle entities missing ActiveSim marker — made them
  invisible to escalation and contamination systems after any load.
- Existing triangle entities not despawned before load — created
  duplicates, doubling tension escalation per tick.

Also: HashSet → BTreeSet for D-010 compliance, defensive event queue
reset on load, and three regression tests for triangle roundtrip.

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

server/src/simulation/save_io.rs

@@ -28,8 +28,10 @@ use crate::simulation::save_state::{
 };
 use crate::knowledge::types::StableId;
 use crate::simulation::interaction::DoorState;
-use crate::simulation::tier::BackgroundSim;
+use crate::simulation::tier::{ActiveSim, BackgroundSim};
 use crate::simulation::time::SimulationTime;
+use crate::content::template::TriangleCrisisEventQueue;
+use crate::storyteller::{ContaminationActive, ContaminationEventQueue};
 
 /// Errors from save/load operations (#553).
 #[derive(Debug, Error)]
@@ -144,6 +146,9 @@ pub fn save_to_file(path: &Path, world: &mut World) -> Result<(), SaveLoadError>
             ids
         },
         modifications: vec![],
+        contamination_active: world
+            .get_resource::<ContaminationActive>()
+            .map_or(false, |c| c.0),
     };
 
     let bytes = state
@@ -170,8 +175,11 @@ pub fn save_to_file(path: &Path, world: &mut World) -> Result<(), SaveLoadError>
 /// 3. Re-spawn each NPC via `deserialize_npc_from_frozen`; register with
 ///    `register_existing`; insert `BackgroundSim` tier marker.
 /// 4. Advance `EntityRegistry` counter past all restored IDs.
-/// 5. Restore `RelationshipGraph`, `SimulationTime`, and `SimRng` resources.
-/// 6. Update the player entity's `KnowledgeGraph` if a player entity exists.
+/// 5. Despawn existing triangle entities (separate from NPCs — no `Npc` marker).
+/// 6. Restore triangle states with `ActiveSim` so escalation/contamination systems see them.
+/// 7. Restore resources: `RelationshipGraph`, `SimulationTime`, `SimRng`,
+///    `ContaminationActive`, event queues (reset to prevent stale cross-load leakage).
+/// 8. Restore door open states and player `KnowledgeGraph`.
 ///
 /// **Gotcha (D-010):** Bevy `Entity` handles are generational. `NpcSaveState` uses
 /// `StableId(u64)` throughout — `EntityRegistry` maps restored `StableId`s to the
@@ -233,9 +241,22 @@ pub fn load_from_file(path: &Path, world: &mut World) -> Result<(), SaveLoadErro
     world.insert_resource(state.relationship_graph);
     world.insert_resource(state.template_references);
 
-    // Restore triangle states (#250) — spawn dedicated entities for each.
+    // Despawn existing triangle entities before restoring from save.
+    // Triangle entities are separate from NPC entities (no Npc component),
+    // so the NPC despawn loop above does not catch them. Without this,
+    // loading a save would create duplicates — doubling tension escalation.
+    let triangle_entities: Vec<Entity> = {
+        let mut q = world.query_filtered::<Entity, With<TriangleState>>();
+        q.iter(world).collect()
+    };
+    for entity in triangle_entities {
+        world.despawn(entity);
+    }
+
+    // Restore triangle states (#250) — spawn with ActiveSim so escalation
+    // and contamination systems (which filter With<ActiveSim>) can see them.
     for ts in &state.triangle_states {
-        world.spawn(ts.clone());
+        world.spawn((ts.clone(), ActiveSim));
     }
     {
         let mut t = world.resource_mut::<SimulationTime>();
@@ -244,9 +265,17 @@ pub fn load_from_file(path: &Path, world: &mut World) -> Result<(), SaveLoadErro
     }
     world.insert_resource(SimRng::new(state.seed));
 
+    // Restore contamination state (#254) — prevents double-firing on reload.
+    world.insert_resource(ContaminationActive(state.contamination_active));
+
+    // Reset event queues — prevent stale events from the pre-load world
+    // leaking into the post-load simulation.
+    world.insert_resource(ContaminationEventQueue::default());
+    world.insert_resource(TriangleCrisisEventQueue::default());
+
     // Restore door open states (#246) — find door entities by StableId and toggle.
     if !state.open_doors.is_empty() {
-        let open_set: std::collections::HashSet<_> = state.open_doors.iter().copied().collect();
+        let open_set: std::collections::BTreeSet<_> = state.open_doors.iter().copied().collect();
         let door_entities: Vec<(Entity, StableId)> = {
             let mut q = world.query::<(Entity, &crate::knowledge::registry::StableEntityId, &DoorState)>();
             q.iter(world)
@@ -560,6 +589,7 @@ mod tests {
             triangle_states: vec![],
             open_doors: vec![],
             modifications: vec![],
+            contamination_active: false,
         };
         let bytes = bad_state.to_bytes().expect("serialize");
         let path = temp_path();
@@ -717,4 +747,118 @@ mod tests {
         assert!(e2.to_string().contains("expected 1"));
         assert!(e2.to_string().contains("found 2"));
     }
+
+    // -----------------------------------------------------------------------
+    // Triangle state roundtrip (regression tests for missing ActiveSim
+    // and duplicate triangle entities on load)
+    // -----------------------------------------------------------------------
+
+    fn make_test_triangle(slug: &str, tension: u8) -> TriangleState {
+        use crate::content::template::{
+            RoleId, TemplateId, TriangleClassification, TriangleId, TrianglePhase,
+        };
+        let mut role_assignments = std::collections::BTreeMap::new();
+        role_assignments.insert(RoleId::new("a"), StableId(1));
+        role_assignments.insert(RoleId::new("b"), StableId(2));
+        role_assignments.insert(RoleId::new("c"), StableId(3));
+
+        TriangleState {
+            triangle_id: TriangleId::from_seed_and_slug(0, slug),
+            role_assignments,
+            tension,
+            phase: TrianglePhase::Simmering,
+            tension_rate: 1,
+            template_id: TemplateId::from_seed_and_slug(0, "test"),
+            classification: TriangleClassification::ActiveFork,
+        }
+    }
+
+    /// Regression: loaded triangle entities must have ActiveSim so that
+    /// escalation and contamination systems (which filter With<ActiveSim>)
+    /// can see them.
+    #[test]
+    fn load_from_file_restores_triangles_with_active_sim() {
+        let mut world = minimal_world();
+        world.init_resource::<ContaminationActive>();
+        world.init_resource::<ContaminationEventQueue>();
+        world.init_resource::<TriangleCrisisEventQueue>();
+
+        world.spawn((make_test_triangle("hub", 15), ActiveSim));
+        world.spawn((make_test_triangle("bar", 30), ActiveSim));
+
+        let path = temp_path();
+        save_to_file(&path, &mut world).expect("save");
+        load_from_file(&path, &mut world).expect("load");
+
+        // All restored triangles must have both TriangleState and ActiveSim.
+        let with_active_sim = {
+            let mut q = world.query_filtered::<Entity, (With<TriangleState>, With<ActiveSim>)>();
+            q.iter(&world).count()
+        };
+        assert_eq!(
+            with_active_sim, 2,
+            "loaded triangles must have ActiveSim — escalation/contamination systems require it"
+        );
+
+        let _ = std::fs::remove_file(&path);
+    }
+
+    /// Regression: loading must not duplicate triangle entities — existing
+    /// triangles must be despawned before restoring from save.
+    #[test]
+    fn load_from_file_does_not_duplicate_triangles() {
+        let mut world = minimal_world();
+        world.init_resource::<ContaminationActive>();
+        world.init_resource::<ContaminationEventQueue>();
+        world.init_resource::<TriangleCrisisEventQueue>();
+
+        world.spawn((make_test_triangle("hub", 10), ActiveSim));
+
+        let path = temp_path();
+        save_to_file(&path, &mut world).expect("save");
+
+        // Load twice — should not accumulate triangles.
+        load_from_file(&path, &mut world).expect("load 1");
+        load_from_file(&path, &mut world).expect("load 2");
+
+        let count = {
+            let mut q = world.query::<&TriangleState>();
+            q.iter(&world).count()
+        };
+        assert_eq!(
+            count, 1,
+            "loading twice must not create duplicate triangle entities"
+        );
+
+        let _ = std::fs::remove_file(&path);
+    }
+
+    /// Triangle tension values must survive save/load roundtrip.
+    #[test]
+    fn load_from_file_preserves_triangle_tension() {
+        let mut world = minimal_world();
+        world.init_resource::<ContaminationActive>();
+        world.init_resource::<ContaminationEventQueue>();
+        world.init_resource::<TriangleCrisisEventQueue>();
+
+        world.spawn((make_test_triangle("hub", 42), ActiveSim));
+        world.spawn((make_test_triangle("bar", 99), ActiveSim));
+
+        let path = temp_path();
+        save_to_file(&path, &mut world).expect("save");
+        load_from_file(&path, &mut world).expect("load");
+
+        let mut tensions: Vec<u8> = {
+            let mut q = world.query::<&TriangleState>();
+            q.iter(&world).map(|ts| ts.tension).collect()
+        };
+        tensions.sort();
+        assert_eq!(
+            tensions,
+            vec![42, 99],
+            "triangle tension values must survive save/load roundtrip"
+        );
+
+        let _ = std::fs::remove_file(&path);
+    }
 }

server/src/simulation/save_state.rs

@@ -105,6 +105,12 @@ pub struct SaveStateV1 {
     /// DLC can populate it without a save format migration.
     #[serde(default)]
     pub modifications: Vec<Modification>,
+    /// Whether contamination has already activated (#254).
+    /// Persisted to prevent double-firing on save/load — without this,
+    /// reloading a save after tick 300 would re-trigger contamination
+    /// and apply a duplicate tension delta to all ActiveFork triangles.
+    #[serde(default)]
+    pub contamination_active: bool,
 }
 
 /// Per-NPC state snapshot for `SaveStateV1`.
@@ -418,6 +424,7 @@ mod tests {
             triangle_states: vec![],
             open_doors: vec![],
             modifications: vec![],
+            contamination_active: false,
         }
     }
 
@@ -816,6 +823,7 @@ mod tests {
             triangle_states: vec![],
             open_doors: vec![],
             modifications: vec![],
+            contamination_active: false,
         };
 
         let bytes = save.to_bytes().expect("serialize");

server/tests/environmental_interaction.rs

@@ -419,6 +419,7 @@ fn minimal_save() -> SaveStateV1 {
         triangle_states: vec![],
         open_doors: vec![],
         modifications: vec![],
+        contamination_active: false,
     }
 }
 

server/tests/information_boundaries.rs

@@ -207,6 +207,7 @@ fn save_state_npc_kg_isolation() {
         triangle_states: vec![],
         open_doors: vec![],
         modifications: vec![],
+        contamination_active: false,
     };
 
     // Roundtrip: serialize → deserialize.