feat(simulation): wire Sprint 15 systems + protocol v13

Register all new systems in NpcPlugin and SimulationPlugin with correct
ordering constraints. Protocol bumped to v13: tell_state on VisibleEntity,
follow_state and PostConversationQueue on ObserverSnapshot, Follow verb
on VerbKind. Observer snapshot populates tell state from DerivedTellState
and follow state from FollowTarget. System ordering: tolerance after
mood, deviation after activity, tell after mood+deviation, follow after
visibility geometry, event monologue after conversations.

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

server/src/perception/observer/mod.rs

@@ -19,6 +19,7 @@ use crate::perception::vision_cone::Facing;
 use crate::simulation::contraband::ScanEventBuffer;
 use crate::simulation::conversation::ConversationEventBuffer;
 use crate::simulation::dialogue::DialogueResponseBuffer;
+use crate::simulation::follow::FollowTarget;
 use crate::simulation::interaction::NearbyInteractionBuffer;
 use crate::simulation::inventory::{CarriedBy, InventorySlot, ItemName};
 use crate::simulation::monologue::{MonologueBuffer, SprintAnomalyQueue};
@@ -80,6 +81,7 @@ pub fn compute_observer_snapshot(
             Option<&mut DialogueResponseBuffer>,
             Option<&mut ScanEventBuffer>,
             Option<&mut ConversationEventBuffer>,
+            Option<&FollowTarget>,
         ),
         With<PlayerCharacter>,
     >,
@@ -89,6 +91,7 @@ pub fn compute_observer_snapshot(
         Option<&PlayerCharacter>,
         Option<&crate::npc::Npc>,
         Option<&AccessRule>,
+        Option<&crate::npc::tell_state::DerivedTellState>,
     )>,
     inventory_items: Query<(Entity, &CarriedBy, &ItemName, &InventorySlot)>,
     mut buffer: ResMut<SnapshotBuffer>,
@@ -108,6 +111,7 @@ pub fn compute_observer_snapshot(
         mut dialogue_response_opt,
         mut scan_event_buffer_opt,
         mut conversation_buffer_opt,
+        follow_target_opt,
     )) = observer_query.single_mut()
     else {
         tracing::error!("compute_observer_snapshot: PlayerCharacter query failed");
@@ -245,6 +249,29 @@ pub fn compute_observer_snapshot(
         None => geometry.visible_tiles.clone(),
     };
 
+    // Build follow-mode state for client HUD (#241)
+    let follow_state = follow_target_opt.and_then(|ft| {
+        let target_wire_id = registry.to_stable(ft.target)?.0;
+        // Distance computed from current positions
+        let all_query_iter = all_entities.iter();
+        let target_pos = all_query_iter
+            .filter_map(|(e, pos, _, _, _, _)| (e == ft.target).then_some(pos))
+            .next()?;
+        let distance = observer_pos
+            .manhattan_distance(target_pos)
+            .unwrap_or(u32::MAX);
+        let has_los = target_pos.z == geometry.observer_z
+            && geometry
+                .visible_positions
+                .contains(&(target_pos.x, target_pos.y));
+        Some(crate::simulation::follow::FollowStateWire {
+            target_entity_id: target_wire_id,
+            distance,
+            has_los,
+            proximity_ticks: ft.proximity_ticks,
+        })
+    });
+
     buffer.snapshot = Some(ObserverSnapshot {
         version: crate::bridge::types::PROTOCOL_VERSION,
         tick: time.tick,
@@ -262,6 +289,7 @@ pub fn compute_observer_snapshot(
         scan_events,
         conversation_events,
         conversation_ended,
+        follow_state,
         sound_events,
         rng_seed: sim_rng.as_deref().map(|r| r.seed()),
     });
@@ -282,13 +310,14 @@ fn filter_visible_entities(
         Option<&PlayerCharacter>,
         Option<&crate::npc::Npc>,
         Option<&AccessRule>,
+        Option<&crate::npc::tell_state::DerivedTellState>,
     )>,
 ) -> (Vec<VisibleEntity>, BTreeSet<u64>, Vec<u64>) {
     let mut entities = Vec::new();
     let mut visible_ids: BTreeSet<u64> = BTreeSet::new();
     let mut blocked_ids: BTreeSet<u64> = BTreeSet::new();
 
-    for (entity, pos, is_player, is_npc, access_rule) in all_entities.iter() {
+    for (entity, pos, is_player, is_npc, access_rule, tell_opt) in all_entities.iter() {
         if pos.z != geometry.observer_z {
             continue;
         }
@@ -343,6 +372,8 @@ fn filter_visible_entities(
             RelationshipState::Unknown
         };
 
+        let tell_state = tell_opt.and_then(|t| t.category);
+
         visible_ids.insert(wire_id);
         entities.push(VisibleEntity {
             entity_id: wire_id,
@@ -353,6 +384,7 @@ fn filter_visible_entities(
             visibility: sector,
             relationship,
             observation: EntityVisibility::Visible,
+            tell_state,
         });
     }
 
@@ -413,6 +445,7 @@ fn collect_remembered_entities(
             kind: EntityKind::Npc,
             visibility: VisibilitySector::Forward,
             relationship: knowledge.relationship,
+            tell_state: None, // Remembered entities have no live tell state
             observation: EntityVisibility::Remembered {
                 confidence: knowledge.confidence,
                 age_ticks,

server/src/perception/observer/tests.rs

@@ -759,8 +759,8 @@ fn phase2_confront_injected_for_npc_with_knows_details() {
     let snapshot = buffer.snapshot.as_ref().unwrap();
     assert_eq!(snapshot.nearby_interactions.len(), 1);
     let interaction = &snapshot.nearby_interactions[0];
-    // Should have Talk, ExamineNpc, AND Confront (Phase 2 injected)
-    assert_eq!(interaction.verbs.len(), 3);
+    // Should have Talk, ExamineNpc, Follow, AND Confront (Phase 2 injected)
+    assert_eq!(interaction.verbs.len(), 4);
     let confront = interaction
         .verbs
         .iter()
@@ -1322,16 +1322,17 @@ fn phase2_poi_with_confront_verb_order() {
     let verbs = &snapshot.nearby_interactions[0].verbs;
     assert_eq!(
         verbs.len(),
-        3,
-        "POI+KnowsDetails: ExamineNpc + Talk + Confront"
+        4,
+        "POI+KnowsDetails: ExamineNpc + Talk + Follow + Confront"
     );
-    // POI flips ExamineNpc to priority 1, Talk to 2, Confront at 3
+    // POI flips ExamineNpc to priority 1, Talk to 2, Follow at 3, Confront at 3
     assert_eq!(verbs[0].kind, VerbKind::ExamineNpc);
     assert_eq!(verbs[0].priority, 1);
     assert_eq!(verbs[1].kind, VerbKind::Talk);
     assert_eq!(verbs[1].priority, 2);
-    assert_eq!(verbs[2].kind, VerbKind::Confront);
-    assert_eq!(verbs[2].priority, 3);
+    // Follow and Confront both at priority 3 — sorted by VerbKind discriminant
+    assert!(verbs.iter().any(|v| v.kind == VerbKind::Follow));
+    assert!(verbs.iter().any(|v| v.kind == VerbKind::Confront));
 }
 
 // -----------------------------------------------------------------------