Merge branch 'phase/42-talk-circles'

Co-authored-by: Cursor <cursoragent@cursor.com>

# Conflicts:
#	docs/phases/README.md
#	src/HSchool.Simulation/PersonLog.cs

src/HSchool.Ai/Decision.cs

@@ -41,7 +41,8 @@ public readonly record struct ActorState(
     IReadOnlyDictionary<string, float> Needs,
     Intent Intent,
     bool LunchWindowOpen = false,
-    ApparelActor Apparel = default);
+    ApparelActor Apparel = default,
+    TalkPlannerContext Talk = default);
 
 /// <summary>
 /// Picks a goal by weight and plans walk-then-do. No world, no clock — a table of inputs to an
@@ -254,6 +255,16 @@ public static class DecisionPlanner
             return Intent.None;
         }
 
+        if (state.BoundToLesson && TalkCircles.BlocksOnLesson(action.DefName))
+        {
+            return Intent.None;
+        }
+
+        if (action.DefName.Equals(TalkActions.PhoneChat, StringComparison.Ordinal) && !state.Talk.HasPhone)
+        {
+            return Intent.None;
+        }
+
         if (RoomFor(catalog, map, walks, state, occupied, action) is null)
         {
             return Intent.None;
@@ -396,8 +407,9 @@ public static class DecisionPlanner
         }
 
         string? best = null;
-        var bestCost = float.PositiveInfinity;
+        var bestScore = float.NegativeInfinity;
         var from = state.NodeId ?? walks.TerritoryId;
+        var candidates = new List<string>();
         foreach (var room in map.Rooms)
         {
             if (!action.Room.Equals(room.Def, StringComparison.Ordinal))
@@ -410,27 +422,37 @@ public static class DecisionPlanner
                 continue;
             }
 
-            var cost = walks.Minutes(from, room.Id);
-            if (float.IsInfinity(cost) || cost > bestCost)
-            {
-                continue;
-            }
-
-            if (cost < bestCost || best is null || string.CompareOrdinal(room.Id, best) < 0)
-            {
-                best = room.Id;
-                bestCost = cost;
-            }
+            candidates.Add(room.Id);
         }
 
         if (map.Territory is { } territory
             && action.Room.Equals(territory.Def, StringComparison.Ordinal)
             && HasSlot(catalog, map, occupied, territory.Id, action.Thing))
         {
-            var cost = walks.Minutes(from, territory.Id);
-            if (!float.IsInfinity(cost) && (best is null || cost < bestCost || (cost == bestCost && string.CompareOrdinal(territory.Id, best) < 0)))
+            candidates.Add(territory.Id);
+        }
+
+        var hasAlternative = candidates.Count > 1;
+        foreach (var nodeId in candidates)
+        {
+            if (action.Lunch
+                && TalkCircles.LunchNodeBlockedByEnemy(nodeId, state.Talk.SelfId ?? "", state.Talk, hasAlternative))
             {
-                best = territory.Id;
+                continue;
+            }
+
+            var cost = walks.Minutes(from, nodeId);
+            if (float.IsInfinity(cost))
+            {
+                continue;
+            }
+
+            var score = -cost + TalkCircles.NodeFriendScore(nodeId, state.Talk.SelfId ?? "", state.Talk);
+            if (score > bestScore
+                || (score == bestScore && (best is null || string.CompareOrdinal(nodeId, best) < 0)))
+            {
+                best = nodeId;
+                bestScore = score;
             }
         }
 

src/HSchool.Ai/TalkCircles.cs

@@ -0,0 +1,377 @@
+using HSchool.Content;
+using HSchool.People;
+
+namespace HSchool.Ai;
+
+/// <summary>Inputs the planner needs for friend pull and lunch avoidance. Built in simulation.</summary>
+public readonly record struct TalkPlannerContext(
+    string? SelfId,
+    IReadOnlyDictionary<string, int> Opinions,
+    IReadOnlyDictionary<string, string> PersonNodes,
+    string? ClassId,
+    bool HasPhone,
+    bool FriendPullActive,
+    BehaviorDef? Rules);
+
+/// <summary>
+/// Pure talk-circle rules: who joins, which topic, opinion and skill math. No world access.
+/// </summary>
+public static class TalkCircles
+{
+    public static bool BlocksOnLesson(string actionId) => TalkActions.IsTalk(actionId);
+
+    public static int MaxSize(string actionId, BehaviorDef? rules, IReadOnlyList<string> traitIds, DefCatalog catalog)
+    {
+        if (actionId.Equals(TalkActions.PhoneChat, StringComparison.Ordinal))
+        {
+            return 2;
+        }
+
+        var max = rules?.TalkCircleMax ?? 4;
+        foreach (var traitId in traitIds)
+        {
+            if (catalog.Traits.TryGetValue(traitId, out var trait))
+            {
+                max += trait.TalkCircleBonus;
+            }
+        }
+
+        return Math.Clamp(max, rules?.TalkCircleMin ?? 2, 4);
+    }
+
+    public static bool IsFriend(int? opinion, BehaviorDef? rules) =>
+        opinion >= (rules?.TalkFriendThreshold ?? 40);
+
+    public static bool IsEnemy(int? opinion, BehaviorDef? rules) =>
+        opinion <= (rules?.TalkEnemyThreshold ?? -40);
+
+    public static bool HasPhone(IReadOnlyList<InventoryItem> items) =>
+        items.Any(item =>
+            item.Def.Equals("Phone", StringComparison.Ordinal)
+            && item.Location.Equals(ItemLocations.Bag, StringComparison.Ordinal));
+
+    public static float Initiative(IReadOnlyList<string> traitIds, DefCatalog catalog)
+    {
+        var weight = 1f;
+        foreach (var traitId in traitIds)
+        {
+            if (catalog.Traits.TryGetValue(traitId, out var trait) && trait.TalkInitiative > 0f)
+            {
+                weight *= trait.TalkInitiative;
+            }
+        }
+
+        return weight;
+    }
+
+    public static float OpinionMultiplier(IReadOnlyList<string> traitIds, DefCatalog catalog)
+    {
+        var mult = 1f;
+        foreach (var traitId in traitIds)
+        {
+            if (catalog.Traits.TryGetValue(traitId, out var trait) && trait.TalkOpinionMultiplier > 0f)
+            {
+                mult *= trait.TalkOpinionMultiplier;
+            }
+        }
+
+        return mult;
+    }
+
+    /// <summary>Score a room node for friend pull on break or lunch.</summary>
+    public static float NodeFriendScore(
+        string nodeId,
+        string selfId,
+        TalkPlannerContext context)
+    {
+        if (!context.FriendPullActive)
+        {
+            return 0f;
+        }
+
+        var score = 0f;
+        foreach (var (personId, otherNode) in context.PersonNodes)
+        {
+            if (personId.Equals(selfId, StringComparison.Ordinal) || otherNode != nodeId)
+            {
+                continue;
+            }
+
+            context.Opinions.TryGetValue(personId, out var opinion);
+            if (IsFriend(opinion, context.Rules))
+            {
+                score += 2f;
+            }
+            else if (IsEnemy(opinion, context.Rules))
+            {
+                score -= 3f;
+            }
+        }
+
+        return score;
+    }
+
+    /// <summary>True when this lunch node should be avoided because an enemy sits there.</summary>
+    public static bool LunchNodeBlockedByEnemy(
+        string nodeId,
+        string selfId,
+        TalkPlannerContext context,
+        bool hasAlternative)
+    {
+        if (!hasAlternative)
+        {
+            return false;
+        }
+
+        foreach (var (personId, otherNode) in context.PersonNodes)
+        {
+            if (personId.Equals(selfId, StringComparison.Ordinal) || otherNode != nodeId)
+            {
+                continue;
+            }
+
+            context.Opinions.TryGetValue(personId, out var opinion);
+            if (IsEnemy(opinion, context.Rules))
+            {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    public static bool RoleFitsTopic(TopicDef topic, bool isStudent, bool isStaff, bool isParent)
+    {
+        if (topic.Roles.Count == 0)
+        {
+            return true;
+        }
+
+        foreach (var role in topic.Roles)
+        {
+            if (role.Equals(PersonRoles.Student, StringComparison.OrdinalIgnoreCase) && isStudent)
+            {
+                return true;
+            }
+
+            if (role.Equals(PersonRoles.Staff, StringComparison.OrdinalIgnoreCase) && isStaff)
+            {
+                return true;
+            }
+
+            if (role.Equals(PersonRoles.Parent, StringComparison.OrdinalIgnoreCase) && isParent)
+            {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    public static bool AgeFits(TopicDef topic, int age)
+    {
+        if (topic.Age is not { } range)
+        {
+            return true;
+        }
+
+        return age >= range.Min && age <= range.Max;
+    }
+
+    public static string? PickTopic(
+        DefCatalog catalog,
+        Person picker,
+        int age,
+        int seed)
+    {
+        var candidates = new List<(TopicDef Topic, float Weight)>();
+        foreach (var topic in catalog.Topics.Values)
+        {
+            if (topic.Abstract
+                || !RoleFitsTopic(topic, picker.IsStudent, picker.IsStaff, picker.IsParent)
+                || !AgeFits(topic, age))
+            {
+                continue;
+            }
+
+            var weight = 1f;
+            foreach (var traitId in picker.Traits)
+            {
+                if (!catalog.Traits.TryGetValue(traitId, out var trait))
+                {
+                    continue;
+                }
+
+                foreach (var bias in trait.TalkTagWeights)
+                {
+                    if (topic.Tags.Contains(bias.Tag, StringComparer.Ordinal))
+                    {
+                        weight *= bias.Weight;
+                    }
+                }
+            }
+
+            candidates.Add((topic, weight));
+        }
+
+        if (candidates.Count == 0)
+        {
+            return null;
+        }
+
+        var total = candidates.Sum(pair => pair.Weight);
+        var roll = (seed & int.MaxValue) % Math.Max(1, (int)(total * 1000)) / 1000f;
+        var cursor = 0f;
+        foreach (var (topic, weight) in candidates.OrderBy(pair => pair.Topic.DefName, StringComparer.Ordinal))
+        {
+            cursor += weight / total;
+            if (roll <= cursor)
+            {
+                return topic.DefName;
+            }
+        }
+
+        return candidates[^1].Topic.DefName;
+    }
+
+    /// <summary>Best shared language skill id among participants, or null.</summary>
+    public static string? SharedLanguage(
+        DefCatalog catalog,
+        IReadOnlyList<Person> participants,
+        BehaviorDef? rules)
+    {
+        var threshold = rules?.TalkLanguageThreshold ?? 25;
+        string? best = null;
+        var bestLevel = 0f;
+        foreach (var skill in catalog.Skills.Values.Where(def =>
+                     !def.Abstract
+                     && !def.DefName.Equals("Communication", StringComparison.Ordinal)
+                     && (def.AdultChance > 0f || def.DefName.EndsWith("Language", StringComparison.Ordinal))))
+        {
+            var min = float.MaxValue;
+            foreach (var person in participants)
+            {
+                if (!person.Skills.TryGetValue(skill.DefName, out var level) || level < threshold)
+                {
+                    min = 0f;
+                    break;
+                }
+
+                min = Math.Min(min, level);
+            }
+
+            if (min >= threshold && min > bestLevel)
+            {
+                bestLevel = min;
+                best = skill.DefName;
+            }
+        }
+
+        return best;
+    }
+
+    public static int AppearanceModifier(ApparelIssue issues) =>
+        issues == ApparelIssue.None ? 2 : issues.HasFlag(ApparelIssue.Formality) ? -2 : 0;
+
+    public static int OpinionDelta(
+        Person from,
+        Person to,
+        TopicDef topic,
+        float communication,
+        bool sharedLanguage,
+        string actionId,
+        ApparelIssue targetAppearance,
+        BehaviorDef? rules,
+        DefCatalog catalog)
+    {
+        var baseShift = topic.OpinionShift;
+        if (topic.Tags.Contains(TopicTags.Appearance, StringComparer.Ordinal))
+        {
+            baseShift += AppearanceModifier(targetAppearance);
+        }
+
+        var commScale = 1f + (communication / 100f) * (rules?.TalkCommunicationOpinionScale ?? 0.5f);
+        var mult = OpinionMultiplier(from.Traits.ToList(), catalog) * commScale;
+        if (!sharedLanguage)
+        {
+            mult *= rules?.TalkNoLanguageOpinionMultiplier ?? 0.15f;
+            if (baseShift > 0)
+            {
+                baseShift = Math.Max(1, baseShift / 3);
+            }
+        }
+
+        if (actionId.Equals(TalkActions.PhoneChat, StringComparison.Ordinal))
+        {
+            mult *= rules?.TalkPhoneOpinionMultiplier ?? 0.5f;
+        }
+
+        var delta = (int)Math.Round(baseShift * mult, MidpointRounding.AwayFromZero);
+        if (!sharedLanguage && delta > 0)
+        {
+            delta = Math.Min(delta, 1);
+        }
+        else if (!sharedLanguage && delta == 0 && baseShift <= 0)
+        {
+            delta = -1;
+        }
+
+        return Math.Clamp(delta, -20, 20);
+    }
+
+    public static float CommunicationGain(
+        float current,
+        SkillDef skill,
+        float hours,
+        BehaviorDef? rules) =>
+        Math.Clamp(current + (rules?.TalkSkillPerHour ?? 0.02f) * hours, skill.Range.Min, skill.Range.Max);
+
+    public static float LanguageGain(
+        float current,
+        SkillDef skill,
+        float hours,
+        BehaviorDef? rules) =>
+        Math.Clamp(current + (rules?.TalkLanguageSkillPerHour ?? 0.005f) * hours, skill.Range.Min, skill.Range.Max);
+
+    /// <summary>Invite priority: friends, classmates, others. Enemies never invited.</summary>
+    public static IReadOnlyList<string> RankInvitees(
+        Person initiator,
+        IReadOnlyList<Candidate> candidates,
+        BehaviorDef? rules)
+    {
+        return candidates
+            .Where(candidate => !candidate.Id.Equals(initiator.Id, StringComparison.Ordinal))
+            .Where(candidate =>
+            {
+                initiator.Opinions.TryGetValue(candidate.Id, out var opinion);
+                return !IsEnemy(opinion, rules);
+            })
+            .OrderByDescending(candidate =>
+            {
+                initiator.Opinions.TryGetValue(candidate.Id, out var opinion);
+                if (IsFriend(opinion, rules))
+                {
+                    return 3;
+                }
+
+                if (initiator.ClassId is not null
+                    && candidate.ClassId is not null
+                    && initiator.ClassId.Equals(candidate.ClassId, StringComparison.Ordinal))
+                {
+                    return 2;
+                }
+
+                return 1;
+            })
+            .ThenBy(candidate => candidate.Id, StringComparer.Ordinal)
+            .Select(candidate => candidate.Id)
+            .ToArray();
+    }
+
+    public readonly record struct Candidate(
+        string Id,
+        string? ClassId,
+        bool IsIdle,
+        bool InCircle,
+        bool HasPhone);
+}

src/HSchool.Content/CatalogLoader.cs

@@ -315,6 +315,7 @@ public sealed class CatalogLoader
         var holidays = new Dictionary<string, HolidayDef>(StringComparer.Ordinal);
         var behavior = new Dictionary<string, BehaviorDef>(StringComparer.Ordinal);
         var colors = new Dictionary<string, ColorDef>(StringComparer.Ordinal);
+        var topics = new Dictionary<string, TopicDef>(StringComparer.Ordinal);
 
         foreach (var (key, json) in resolved)
         {
@@ -380,6 +381,9 @@ public sealed class CatalogLoader
                 case DefKind.Color:
                     colors[key.Name] = Jsonc.Deserialize<ColorDef>(json);
                     break;
+                case DefKind.Topic:
+                    topics[key.Name] = Jsonc.Deserialize<TopicDef>(json);
+                    break;
             }
         }
 
@@ -405,6 +409,7 @@ public sealed class CatalogLoader
             holidays,
             behavior,
             colors,
+            topics,
             ru,
             en);
     }

src/HSchool.Content/DefCatalog.cs

@@ -28,6 +28,7 @@ public sealed class DefCatalog
         IReadOnlyDictionary<string, HolidayDef> holidays,
         IReadOnlyDictionary<string, BehaviorDef> behavior,
         IReadOnlyDictionary<string, ColorDef> colors,
+        IReadOnlyDictionary<string, TopicDef> topics,
         IReadOnlyDictionary<string, string> ru,
         IReadOnlyDictionary<string, string> en)
     {
@@ -52,6 +53,7 @@ public sealed class DefCatalog
         Holidays = holidays;
         Behavior = behavior;
         Colors = colors;
+        Topics = topics;
         _ru = ru;
         _en = en;
         AnyNeedDecays = needs.Values.Any(need => !need.Abstract && need.DecayPerHour > 0f);
@@ -109,6 +111,8 @@ public sealed class DefCatalog
 
     public IReadOnlyDictionary<string, ColorDef> Colors { get; }
 
+    public IReadOnlyDictionary<string, TopicDef> Topics { get; }
+
     /// <summary>The one concrete staffing ruleset, or null when a pack has not defined it.</summary>
     public StaffingDef? StaffingRules => Staffing.Values.FirstOrDefault(def => !def.Abstract);
 
@@ -145,6 +149,7 @@ public sealed class DefCatalog
             DefKind.Holiday => Holidays.GetValueOrDefault(defName),
             DefKind.Behavior => Behavior.GetValueOrDefault(defName),
             DefKind.Color => Colors.GetValueOrDefault(defName),
+            DefKind.Topic => Topics.GetValueOrDefault(defName),
             _ => null,
         };
 
@@ -225,6 +230,7 @@ public sealed class DefCatalog
         HolidayDef => DefKind.Holiday,
         BehaviorDef => DefKind.Behavior,
         ColorDef => DefKind.Color,
+        TopicDef => DefKind.Topic,
         _ => throw new ArgumentOutOfRangeException(nameof(def)),
     };
 

src/HSchool.Content/Defs.cs

@@ -22,6 +22,7 @@ public enum DefKind
     Holiday,
     Behavior,
     Color,
+    Topic,
 }
 
 /// <summary>Shared JSONC fields. Kind comes from the folder under <c>defs/</c>, not from the file.</summary>

src/HSchool.Content/PackPaths.cs

@@ -129,6 +129,9 @@ internal static class PackPaths
             case "colors":
                 kind = DefKind.Color;
                 return true;
+            case "topics":
+                kind = DefKind.Topic;
+                return true;
             default:
                 kind = default;
                 return false;

src/HSchool.Content/PeopleDefValidator.cs

@@ -65,6 +65,13 @@ internal static class PeopleDefValidator
             ValidateBehavior(behavior, log);
         }
 
+        foreach (var topic in catalog.Topics.Values)
+        {
+            ValidateTopic(topic, catalog);
+        }
+
+        RequireTalkTopics(catalog);
+
         if (catalog.Staffing.Values.Count(def => !def.Abstract) > 1)
         {
             throw new ContentLoadException("A catalog may only have one concrete StaffingDef.");
@@ -550,6 +557,63 @@ internal static class PeopleDefValidator
             log.Warning(
                 $"BehaviorDef '{behavior.DefName}' lunchWeight {behavior.LunchWeight} is above dutyLessonWeight {behavior.DutyLessonWeight}; pupils will leave class for lunch.");
         }
+
+        if (behavior.TalkCircleMin < 2 || behavior.TalkCircleMax < behavior.TalkCircleMin)
+        {
+            throw new ContentLoadException(
+                $"BehaviorDef '{behavior.DefName}' talk circle size must be at least 2 with max ≥ min.");
+        }
+    }
+
+    private static void ValidateTopic(TopicDef topic, DefCatalog catalog)
+    {
+        if (topic.Abstract)
+        {
+            return;
+        }
+
+        if (topic.Tags.Count == 0)
+        {
+            throw new ContentLoadException($"TopicDef '{topic.DefName}' needs at least one tag.");
+        }
+
+        if (topic.Age is { Min: var min, Max: var max } && min > max)
+        {
+            throw new ContentLoadException($"TopicDef '{topic.DefName}' age min cannot exceed max.");
+        }
+
+        foreach (var role in topic.Roles)
+        {
+            if (!PersonRoles.IsKnown(role))
+            {
+                throw new ContentLoadException($"TopicDef '{topic.DefName}' has unknown role '{role}'.");
+            }
+        }
+
+        if (topic.Language is not null && !catalog.Skills.ContainsKey(topic.Language))
+        {
+            throw new ContentLoadException($"TopicDef '{topic.DefName}' references unknown SkillDef '{topic.Language}'.");
+        }
+    }
+
+    /// <summary>A catalog with circle actions but no topics would silently solo-chat — refuse load.</summary>
+    private static void RequireTalkTopics(DefCatalog catalog)
+    {
+        var hasTalkAction = catalog.Actions.Values.Any(action =>
+            !action.Abstract
+            && (action.DefName.Equals(TalkActions.Chat, StringComparison.Ordinal)
+                || action.DefName.Equals(TalkActions.StaffChat, StringComparison.Ordinal)
+                || action.DefName.Equals(TalkActions.PhoneChat, StringComparison.Ordinal)));
+        if (!hasTalkAction)
+        {
+            return;
+        }
+
+        if (!catalog.Topics.Values.Any(topic => !topic.Abstract))
+        {
+            throw new ContentLoadException(
+                "A catalog with talk actions requires at least one concrete TopicDef.");
+        }
     }
 
     private static void ValidateConditionBands(BehaviorDef behavior)

src/HSchool.Content/PeopleDefs.cs

@@ -162,6 +162,14 @@ public sealed class TraitSkillModifier
     public int Offset { get; init; }
 }
 
+/// <summary>Biases topic pick toward a tag. Used on gossip and similar traits.</summary>
+public sealed class TopicTagWeight
+{
+    public required string Tag { get; init; }
+
+    public float Weight { get; init; } = 1f;
+}
+
 public sealed class TraitDef : Def
 {
     public int Weight { get; init; } = 1;
@@ -190,6 +198,39 @@ public sealed class TraitDef : Def
     /// cold-loving is negative.
     /// </summary>
     public float ComfortTemperatureOffset { get; init; }
+
+    /// <summary>How often this person initiates talk. Quiet below 1, leader above.</summary>
+    public float TalkInitiative { get; init; } = 1f;
+
+    /// <summary>Extra seats preferred in a circle. Social trait raises it.</summary>
+    public int TalkCircleBonus { get; init; }
+
+    /// <summary>Multiplies opinion shift from talk. Gossip above 1.</summary>
+    public float TalkOpinionMultiplier { get; init; } = 1f;
+
+    /// <summary>Pull toward topics carrying these tags when this person picks the subject.</summary>
+    public IReadOnlyList<TopicTagWeight> TalkTagWeights { get; init; } = [];
+}
+
+/// <summary>Conversation subject. Tags gate appropriateness; language is optional skill help.</summary>
+public sealed class TopicDef : Def
+{
+    /// <summary>Vanilla tags: study, games, food, family, sport, gossip, rude, appearance.</summary>
+    public IReadOnlyList<string> Tags { get; init; } = [];
+
+    public IntRange? Age { get; init; }
+
+    /// <summary>Empty means every role.</summary>
+    public IReadOnlyList<string> Roles { get; init; } = [];
+
+    /// <summary>Allowed as whisper on lesson — phase 43 uses this; ordinary Chat does not.</summary>
+    public bool WhisperOnLesson { get; init; }
+
+    /// <summary>Skill that helps when shared above threshold. Null — any language works equally.</summary>
+    public string? Language { get; init; }
+
+    /// <summary>Base opinion shift toward each other participant when talk succeeds.</summary>
+    public int OpinionShift { get; init; } = 2;
 }
 
 public sealed class StaffingDef : Def
@@ -329,6 +370,36 @@ public sealed class BehaviorDef : Def
     /// </summary>
     public IReadOnlyList<OpinionBand> OpinionBands { get; init; } = DefaultOpinionBands;
 
+    /// <summary>Skill points Communication gains per game hour of talk — less than a lesson.</summary>
+    public float TalkSkillPerHour { get; init; } = 0.02f;
+
+    /// <summary>Language used in talk, when not already at skill max.</summary>
+    public float TalkLanguageSkillPerHour { get; init; } = 0.005f;
+
+    /// <summary>Minimum shared language skill for full opinion shift.</summary>
+    public int TalkLanguageThreshold { get; init; } = 25;
+
+    /// <summary>Opinion multiplier when participants share no language above threshold.</summary>
+    public float TalkNoLanguageOpinionMultiplier { get; init; } = 0.15f;
+
+    /// <summary>Opinion multiplier for phone chat vs live circle.</summary>
+    public float TalkPhoneOpinionMultiplier { get; init; } = 0.5f;
+
+    /// <summary>How much Communication scales opinion shift (per 100 points).</summary>
+    public float TalkCommunicationOpinionScale { get; init; } = 0.5f;
+
+    /// <summary>Minimum circle size. Below this Chat does not start.</summary>
+    public int TalkCircleMin { get; init; } = 2;
+
+    /// <summary>Maximum people in one live circle.</summary>
+    public int TalkCircleMax { get; init; } = 4;
+
+    /// <summary>Opinion at or above — friend for invites and node pull.</summary>
+    public int TalkFriendThreshold { get; init; } = 40;
+
+    /// <summary>Opinion at or below — enemy; never invited, lunch nodes avoided.</summary>
+    public int TalkEnemyThreshold { get; init; } = -40;
+
     public static IReadOnlyList<OpinionBand> DefaultOpinionBands { get; } =
     [
         new() { Min = 70, Id = "OpinionCloseFriend" },

src/HSchool.Content/TalkActions.cs

@@ -0,0 +1,28 @@
+namespace HSchool.Content;
+
+/// <summary>Leisure actions that form talk circles. Names match ActionDef ids in core.</summary>
+public static class TalkActions
+{
+    public const string Chat = "Chat";
+    public const string StaffChat = "StaffChat";
+    public const string PhoneChat = "PhoneChat";
+
+    public static bool IsTalk(string? actionId) =>
+        actionId is not null
+        && (actionId.Equals(Chat, StringComparison.Ordinal)
+            || actionId.Equals(StaffChat, StringComparison.Ordinal)
+            || actionId.Equals(PhoneChat, StringComparison.Ordinal));
+}
+
+/// <summary>Vanilla topic tags from the social slice design doc.</summary>
+public static class TopicTags
+{
+    public const string Study = "study";
+    public const string Games = "games";
+    public const string Food = "food";
+    public const string Family = "family";
+    public const string Sport = "sport";
+    public const string Gossip = "gossip";
+    public const string Rude = "rude";
+    public const string Appearance = "appearance";
+}

src/HSchool.Server/mods/core/defs/actions/living.jsonc

@@ -36,6 +36,24 @@
     "roles": ["student", "staff"],
     "weight": 3,
   },
+  {
+    "defName": "StaffChat",
+    "room": "TeachersRoom",
+    "minutes": 8,
+    "need": "Social",
+    "needGain": 0.4,
+    "roles": ["staff"],
+    "weight": 3,
+  },
+  {
+    "defName": "PhoneChat",
+    "room": "Corridor",
+    "minutes": 6,
+    "need": "Social",
+    "needGain": 0.25,
+    "roles": ["student"],
+    "weight": 2,
+  },
   {
     "defName": "WalkCorridor",
     "room": "Corridor",

src/HSchool.Server/mods/core/defs/behavior/rules.jsonc

@@ -62,4 +62,15 @@
     { "min": -40, "id": "OpinionDislike" },
     { "min": -100, "id": "OpinionEnemy" },
   ],
+  // Talk circles (slice 9 phase 42). Communication per hour is well below lessonSkillPerHour.
+  "talkSkillPerHour": 0.02,
+  "talkLanguageSkillPerHour": 0.005,
+  "talkLanguageThreshold": 25,
+  "talkNoLanguageOpinionMultiplier": 0.15,
+  "talkPhoneOpinionMultiplier": 0.5,
+  "talkCommunicationOpinionScale": 0.5,
+  "talkCircleMin": 2,
+  "talkCircleMax": 4,
+  "talkFriendThreshold": 40,
+  "talkEnemyThreshold": -40,
 }

src/HSchool.Server/mods/core/defs/topics/vanilla.jsonc

@@ -0,0 +1,52 @@
+[
+  {
+    "defName": "TopicStudy",
+    "tags": ["study"],
+    "roles": ["student", "staff"],
+    "opinionShift": 2,
+  },
+  {
+    "defName": "TopicGames",
+    "tags": ["games"],
+    "roles": ["student"],
+    "age": { "min": 7, "max": 18 },
+    "opinionShift": 3,
+  },
+  {
+    "defName": "TopicFood",
+    "tags": ["food"],
+    "roles": ["student", "staff"],
+    "opinionShift": 2,
+  },
+  {
+    "defName": "TopicFamily",
+    "tags": ["family"],
+    "roles": ["student", "staff"],
+    "opinionShift": 2,
+  },
+  {
+    "defName": "TopicSport",
+    "tags": ["sport"],
+    "roles": ["student", "staff"],
+    "opinionShift": 3,
+  },
+  {
+    "defName": "TopicGossip",
+    "tags": ["gossip"],
+    "roles": ["student", "staff"],
+    "opinionShift": 1,
+  },
+  {
+    "defName": "TopicRude",
+    "tags": ["rude"],
+    "roles": ["student", "staff"],
+    "opinionShift": -3,
+  },
+  {
+    "defName": "TopicAppearance",
+    "tags": ["appearance"],
+    "roles": ["student"],
+    "age": { "min": 11, "max": 18 },
+    "opinionShift": 1,
+  },
+]

src/HSchool.Server/mods/core/defs/traits/traits.jsonc

@@ -34,12 +34,14 @@
     "weight": 7,
     "incompatible": ["Leader", "Bully"],
     "wageAsk": -8,
+    "talkInitiative": 0.45,
   },
   {
     "defName": "Leader",
     "weight": 4,
     "incompatible": ["Quiet"],
     "wageAsk": 10,
+    "talkInitiative": 1.6,
     "skillModifiers": [
       { "skill": "History", "offset": 4 },
     ],
@@ -92,4 +94,18 @@
     "incompatible": ["HeatLoving"],
     "comfortTemperatureOffset": -4,
   },
+  {
+    "defName": "Gossip",
+    "weight": 5,
+    "roles": ["student", "staff"],
+    "talkOpinionMultiplier": 1.5,
+    "talkTagWeights": [{ "tag": "gossip", "weight": 3 }],
+  },
+  {
+    "defName": "Outgoing",
+    "weight": 6,
+    "incompatible": ["Quiet"],
+    "talkInitiative": 1.4,
+    "talkCircleBonus": 1,
+  },
 ]

src/HSchool.Server/mods/core/localizations/en.jsonc

@@ -4,6 +4,8 @@
   "UseToilet": "Restroom",
   "RecessRest": "Recess",
   "Chat": "Chat",
+  "StaffChat": "Staff chat",
+  "PhoneChat": "Phone chat",
   "WalkCorridor": "Walk the corridor",
   "WalkYard": "Walk the yard",
   "Behavior": "Behavior rules",
@@ -139,6 +141,8 @@
   "Curious": "Curious",
   "HotTempered": "Hot-tempered",
   "Kind": "Kind",
+  "Gossip": "Gossip",
+  "Outgoing": "Outgoing",
   "Neat": "Neat",
   "Staffing": "Staffing",
   "Height": "Height",
@@ -189,6 +193,15 @@
   "OpinionEnemy": "enemies",
   "ActionStarted": "started: {0}",
   "ActionEnded": "finished: {0}",
+  "TalkEnded": "talked about {0}",
+  "TopicStudy": "schoolwork",
+  "TopicGames": "games",
+  "TopicFood": "food",
+  "TopicFamily": "family",
+  "TopicSport": "sport",
+  "TopicGossip": "gossip",
+  "TopicRude": "rough talk",
+  "TopicAppearance": "looks",
   "ApparelReplaced": "got a new {0}",
   "ApparelChanged": "changed clothes: {0}",
   "LessonNoTeacher": "lesson without a teacher: {0}",

src/HSchool.Server/mods/core/localizations/ru.jsonc

@@ -4,6 +4,8 @@
   "UseToilet": "Туалет",
   "RecessRest": "Перемена",
   "Chat": "Разговор",
+  "StaffChat": "Разговор в учительской",
+  "PhoneChat": "Разговор по телефону",
   "WalkCorridor": "Прогулка по коридору",
   "WalkYard": "Прогулка во дворе",
   "Behavior": "Правила поведения",
@@ -139,6 +141,8 @@
   "Curious": "Любопытный",
   "HotTempered": "Вспыльчивый",
   "Kind": "Добрый",
+  "Gossip": "Сплетник",
+  "Outgoing": "Общительный",
   "Neat": "Аккуратный",
   "Staffing": "Штат",
   "Height": "Рост",
@@ -189,6 +193,15 @@
   "OpinionEnemy": "враги",
   "ActionStarted": "начал: {0}",
   "ActionEnded": "закончил: {0}",
+  "TalkEnded": "говорил о {0}",
+  "TopicStudy": "учёбе",
+  "TopicGames": "играх",
+  "TopicFood": "еде",
+  "TopicFamily": "семье",
+  "TopicSport": "спорте",
+  "TopicGossip": "сплетнях",
+  "TopicRude": "грубом",
+  "TopicAppearance": "внешности",
   "ApparelReplaced": "получил новую {0}",
   "ApparelChanged": "переоделся: {0}",
   "LessonNoTeacher": "урок без учителя: {0}",

src/HSchool.Simulation/ActivitySystem.cs

@@ -21,6 +21,11 @@ internal static class ActivitySystem
             return false;
         }
 
+        if (TalkActions.IsTalk(actionId))
+        {
+            return TalkCircleSystem.TryStart(school, personId, actionId);
+        }
+
         if (!school.Catalog.Actions.TryGetValue(actionId, out var action) || action.Abstract)
         {
             return false;
@@ -114,6 +119,11 @@ internal static class ActivitySystem
                 return;
             }
 
+            if (TalkActions.IsTalk(activity.ActionId))
+            {
+                return;
+            }
+
             var location = school.Map?.NodeDef(presence.NodeId ?? "");
             if (location is null || !location.Equals(action.Room, StringComparison.Ordinal))
             {

src/HSchool.Simulation/PersonLog.cs

@@ -12,6 +12,7 @@ public static class PersonLogTypes
 {
     public const string ActionStarted = "action-started";
     public const string ActionEnded = "action-ended";
+    public const string TalkEnded = "talk-ended";
     public const string ApparelReplaced = "apparel-replaced";
     public const string ApparelChanged = "apparel-changed";
     public const string LessonNoTeacher = "lesson-no-teacher";
@@ -67,6 +68,14 @@ public sealed record PersonLogEvent(string PersonId, DateTime Time, string Type,
             return string.Format(CultureInfo.InvariantCulture, catalog.Text(locale, "LessonNoTeacher"), name);
         }
 
+        if (Type.Equals(PersonLogTypes.TalkEnded, StringComparison.Ordinal))
+        {
+            var topic = catalog.Topics.TryGetValue(ThingDef ?? "", out var def)
+                ? catalog.Label(locale, def)
+                : ThingDef ?? Type;
+            return string.Format(CultureInfo.InvariantCulture, catalog.Text(locale, "TalkEnded"), topic);
+        }
+
         return Type;
     }
 }

src/HSchool.Simulation/PresenceSystem.cs

@@ -324,6 +324,23 @@ internal static class PresenceSystem
     {
         var now = school.Clock.Time;
         var walks = school.Walks!;
+        var slot = SchoolDay.At(school.Catalog!, now, school.SchoolWeekDays);
+        var weekday = SchoolDay.WeekdayIndex(now);
+        var lessons = Duty.LessonsToday(person, ClassOf(school, person), school.Timetable, weekday);
+        var bound = Duty.IsOtherStaff(person)
+            ? slot.Kind != DaySlotKind.Outside
+            : slot.Kind == DaySlotKind.Lesson && lessons.Any(lesson => lesson.Period == slot.Index);
+        if (activity.IsActive && TalkActions.IsTalk(activity.ActionId))
+        {
+            if (!bound)
+            {
+                return null;
+            }
+
+            TalkCircleSystem.Interrupt(school, person.Id);
+            activity = PersonActivity.Idle;
+        }
+
         if (!presence.IsOnCampus)
         {
             intent = Intent.None;
@@ -369,16 +386,11 @@ internal static class PresenceSystem
             return null;
         }
 
-        var slot = SchoolDay.At(school.Catalog!, now, school.SchoolWeekDays);
-        var weekday = SchoolDay.WeekdayIndex(now);
-        var lessons = Duty.LessonsToday(person, ClassOf(school, person), school.Timetable, weekday);
-        var bound = Duty.IsOtherStaff(person)
-            ? slot.Kind != DaySlotKind.Outside
-            : slot.Kind == DaySlotKind.Lesson && lessons.Any(lesson => lesson.Period == slot.Index);
         var frame = school.Catalog!.DayFrame;
         var lunchOpen = frame is not null
             && SchoolDay.IsLunchWindow(frame, slot, ClassOf(school, person)?.Year);
         var apparel = ApparelPresence.Build(school, person, ClassOf(school, person));
+        var talk = BuildTalkContext(school, person, bound, lunchOpen, slot);
         var state = new ActorState(
             presence.NodeId,
             presence.DestinationId,
@@ -392,7 +404,8 @@ internal static class PresenceSystem
             needs.Values,
             intent,
             lunchOpen,
-            apparel);
+            apparel,
+            talk);
         var decision = DecisionPlanner.Decide(
             school.Catalog!,
             school.Map!,
@@ -401,17 +414,19 @@ internal static class PresenceSystem
             (node, thing) => occupied.GetValueOrDefault((node, thing)));
 
         var changing = activity.IsActive && ActivitySystem.IsChangeClothes(activity.ActionId);
+        var inTalk = activity.IsActive && TalkActions.IsTalk(activity.ActionId);
 
         if (decision.WalkTo is not null
             && !decision.WalkTo.Equals(presence.NodeId, StringComparison.Ordinal)
             && activity.IsActive
-            && !changing)
+            && !changing
+            && !inTalk)
         {
             activity = PersonActivity.Idle;
         }
 
         intent = decision.Intent;
-        if (decision.WalkTo is not null && !changing)
+        if (decision.WalkTo is not null && !changing && !inTalk)
         {
             presence = PresenceStepper.StartWalk(presence, walks, decision.WalkTo, headingHome: false);
         }
@@ -523,6 +538,40 @@ internal static class PresenceSystem
         return new Intent(kind, row.GoalId, row.GoalWeight, row.GoalAction);
     }
 
+    private static TalkPlannerContext BuildTalkContext(
+        School school,
+        Person person,
+        bool boundToLesson,
+        bool lunchOpen,
+        DaySlot slot)
+    {
+        var opinions = person.Opinions as IReadOnlyDictionary<string, int> ?? new Dictionary<string, int>(StringComparer.Ordinal);
+        var nodes = SnapshotPersonNodes(school);
+        var friendPull = !boundToLesson && (slot.Kind == DaySlotKind.Break || lunchOpen);
+        return new TalkPlannerContext(
+            person.Id,
+            opinions,
+            nodes,
+            person.ClassId,
+            TalkCircles.HasPhone(person.Items),
+            friendPull,
+            school.Catalog?.BehaviorRules);
+    }
+
+    private static Dictionary<string, string> SnapshotPersonNodes(School school)
+    {
+        var nodes = new Dictionary<string, string>(StringComparer.Ordinal);
+        var world = school.World;
+        world.Query(in People, (ref PersonIdentity identity, ref Presence presence) =>
+        {
+            if (presence.IsOnCampus && presence.NodeId is not null)
+            {
+                nodes[identity.Id] = presence.NodeId;
+            }
+        });
+        return nodes;
+    }
+
     private static SchoolClass? ClassOf(School school, Person person)
     {
         if (person.ClassId is null)

src/HSchool.Simulation/School.cs

@@ -132,6 +132,10 @@ public sealed class School : IDisposable
 
     internal Dictionary<string, string?> LoggedActivity { get; } = new(StringComparer.Ordinal);
 
+    internal Dictionary<string, ActiveTalkCircle> TalkCirclesById { get; } = new(StringComparer.Ordinal);
+
+    internal Dictionary<string, string> TalkCircleByPerson { get; } = new(StringComparer.Ordinal);
+
     internal void ResetDayLog()
     {
         _dayLog.Clear();
@@ -356,6 +360,11 @@ public sealed class School : IDisposable
             PresenceSystem.Enqueue(this, id);
         }
 
+        foreach (var id in TalkCircleSystem.Apply(this, gameMinutes))
+        {
+            PresenceSystem.Enqueue(this, id);
+        }
+
         PersonDayLog.Sync(this);
 
         if (Catalog is not null)

src/HSchool.Simulation/TalkCircleSystem.cs

@@ -0,0 +1,487 @@
+using Arch.Core;
+using HSchool.Ai;
+using HSchool.Content;
+using HSchool.People;
+
+namespace HSchool.Simulation;
+
+internal sealed class ActiveTalkCircle
+{
+    public required string Id { get; init; }
+
+    public required string ActionId { get; init; }
+
+    public required string TopicId { get; init; }
+
+    public required string NodeId { get; init; }
+
+    public required List<string> Members { get; init; }
+
+    public float RemainingMinutes { get; set; }
+}
+
+/// <summary>Forms 2–4 person talk circles, applies outcomes, writes topic log lines.</summary>
+internal static class TalkCircleSystem
+{
+    private static readonly QueryDescription People =
+        new QueryDescription().WithAll<PersonIdentity, PersonRoles, PersonTraits, PersonSkills, PersonNeeds, Presence, PersonActivity>();
+
+    public static bool IsInCircle(School school, string personId) =>
+        school.TalkCircleByPerson.ContainsKey(personId);
+
+    /// <summary>Ends an active circle when duty overrides break talk (bell rang).</summary>
+    public static void Interrupt(School school, string personId)
+    {
+        if (!school.TalkCircleByPerson.TryGetValue(personId, out var circleId)
+            || !school.TalkCirclesById.TryGetValue(circleId, out var circle))
+        {
+            return;
+        }
+
+        Finish(school, circle);
+    }
+
+    public static bool TryStart(School school, string personId, string actionId)
+    {
+        if (school.Catalog is null || school.Map is null || school.Roster is null)
+        {
+            return false;
+        }
+
+        if (!TalkActions.IsTalk(actionId) || !school.Catalog.Actions.TryGetValue(actionId, out var action) || action.Abstract)
+        {
+            return false;
+        }
+
+        if (school.TalkCircleByPerson.ContainsKey(personId))
+        {
+            return true;
+        }
+
+        var person = school.Roster.People.FirstOrDefault(row => row.Id.Equals(personId, StringComparison.Ordinal));
+        if (person is null)
+        {
+            return false;
+        }
+
+        string? nodeId = null;
+        var busy = false;
+        school.World.Query(in People, (ref PersonIdentity identity, ref Presence presence, ref PersonActivity activity) =>
+        {
+            if (!identity.Id.Equals(personId, StringComparison.Ordinal))
+            {
+                return;
+            }
+
+            nodeId = presence.NodeId;
+            busy = activity.IsActive;
+        });
+
+        if (nodeId is null || busy)
+        {
+            return false;
+        }
+
+        var location = school.Map.NodeDef(nodeId);
+        if (location is null || !location.Equals(action.Room, StringComparison.Ordinal))
+        {
+            return false;
+        }
+
+        if (action.DefName.Equals(TalkActions.PhoneChat, StringComparison.Ordinal))
+        {
+            return TryStartPhone(school, person, nodeId, action);
+        }
+
+        var existing = FindOpenCircle(school, nodeId, actionId);
+        if (existing is not null)
+        {
+            return JoinCircle(school, existing, personId, action);
+        }
+
+        return TryStartGroup(school, person, nodeId, action);
+    }
+
+    public static IReadOnlyList<string> Apply(School school, double gameMinutes)
+    {
+        if (gameMinutes <= 0 || school.Catalog is null || school.Roster is null)
+        {
+            return [];
+        }
+
+        var minutes = (float)gameMinutes;
+        var completed = new List<string>();
+        foreach (var circle in school.TalkCirclesById.Values.ToArray())
+        {
+            circle.RemainingMinutes -= minutes;
+            SyncActivity(school, circle);
+            if (circle.RemainingMinutes > 0)
+            {
+                continue;
+            }
+
+            Finish(school, circle);
+            completed.AddRange(circle.Members);
+        }
+
+        completed.Sort(StringComparer.Ordinal);
+        return completed;
+    }
+
+    private static bool TryStartPhone(School school, Person initiator, string nodeId, ActionDef action)
+    {
+        if (!TalkCircles.HasPhone(initiator.Items))
+        {
+            return false;
+        }
+
+        var candidates = GatherCandidates(school, initiator.Id, nodeId, requirePhone: true);
+        var ranked = TalkCircles.RankInvitees(initiator, candidates, school.Catalog!.BehaviorRules);
+        if (ranked.Count == 0)
+        {
+            return false;
+        }
+
+        var partnerId = ranked[0];
+        var partner = school.Roster!.People.First(row => row.Id.Equals(partnerId, StringComparison.Ordinal));
+        if (!TalkCircles.HasPhone(partner.Items))
+        {
+            return false;
+        }
+
+        var topicId = TalkCircles.PickTopic(
+            school.Catalog!,
+            initiator,
+            initiator.AgeOn(school.Clock.Time),
+            Seed.Mix(school.PeopleSeed, initiator.Id, DateOnly.FromDateTime(school.Clock.Time).DayNumber, Seed.ApparelSalt + 20))
+            ?? school.Catalog!.Topics.Values.First(topic => !topic.Abstract).DefName;
+
+        var circle = new ActiveTalkCircle
+        {
+            Id = $"phone-{initiator.Id}-{partnerId}",
+            ActionId = action.DefName,
+            TopicId = topicId,
+            NodeId = nodeId,
+            Members = [initiator.Id, partnerId],
+            RemainingMinutes = action.Minutes,
+        };
+        Register(school, circle, action);
+        return true;
+    }
+
+    private static bool TryStartGroup(School school, Person initiator, string nodeId, ActionDef action)
+    {
+        var rules = school.Catalog!.BehaviorRules;
+        var max = TalkCircles.MaxSize(action.DefName, rules, initiator.Traits, school.Catalog);
+        var candidates = GatherCandidates(school, initiator.Id, nodeId, requirePhone: false);
+        var ranked = TalkCircles.RankInvitees(initiator, candidates, rules);
+        var members = new List<string> { initiator.Id };
+        foreach (var id in ranked)
+        {
+            if (members.Count >= max)
+            {
+                break;
+            }
+
+            members.Add(id);
+        }
+
+        var min = rules?.TalkCircleMin ?? 2;
+        if (members.Count < min)
+        {
+            return false;
+        }
+
+        var topicId = TalkCircles.PickTopic(
+            school.Catalog,
+            initiator,
+            initiator.AgeOn(school.Clock.Time),
+            Seed.Mix(school.PeopleSeed, initiator.Id, DateOnly.FromDateTime(school.Clock.Time).DayNumber, Seed.ApparelSalt + 21))
+            ?? school.Catalog.Topics.Values.First(topic => !topic.Abstract).DefName;
+
+        var circle = new ActiveTalkCircle
+        {
+            Id = $"talk-{initiator.Id}-{nodeId}-{school.Clock.Time.Ticks}",
+            ActionId = action.DefName,
+            TopicId = topicId,
+            NodeId = nodeId,
+            Members = members,
+            RemainingMinutes = action.Minutes,
+        };
+        Register(school, circle, action);
+        return true;
+    }
+
+    private static bool JoinCircle(School school, ActiveTalkCircle circle, string personId, ActionDef action)
+    {
+        var rules = school.Catalog!.BehaviorRules;
+        var person = school.Roster!.People.First(row => row.Id.Equals(personId, StringComparison.Ordinal));
+        var max = TalkCircles.MaxSize(action.DefName, rules, person.Traits, school.Catalog);
+        if (circle.Members.Count >= max || circle.Members.Contains(personId))
+        {
+            return false;
+        }
+
+        circle.Members.Add(personId);
+        circle.Members.Sort(StringComparer.Ordinal);
+        school.TalkCircleByPerson[personId] = circle.Id;
+        SetActivity(school, personId, action.DefName, circle.TopicId, circle.RemainingMinutes);
+        return true;
+    }
+
+    private static ActiveTalkCircle? FindOpenCircle(School school, string nodeId, string actionId)
+    {
+        foreach (var circle in school.TalkCirclesById.Values)
+        {
+            if (circle.NodeId.Equals(nodeId, StringComparison.Ordinal)
+                && circle.ActionId.Equals(actionId, StringComparison.Ordinal)
+                && circle.RemainingMinutes > 0)
+            {
+                var rules = school.Catalog!.BehaviorRules;
+                var max = rules?.TalkCircleMax ?? 4;
+                if (circle.Members.Count < max)
+                {
+                    return circle;
+                }
+            }
+        }
+
+        return null;
+    }
+
+    private static IReadOnlyList<TalkCircles.Candidate> GatherCandidates(
+        School school,
+        string exceptId,
+        string nodeId,
+        bool requirePhone)
+    {
+        var roster = school.Roster!.People.ToDictionary(person => person.Id, StringComparer.Ordinal);
+        var list = new List<TalkCircles.Candidate>();
+        school.World.Query(
+            in People,
+            (ref PersonIdentity identity, ref PersonRoles roles, ref Presence presence, ref PersonActivity activity) =>
+            {
+                if (identity.Id.Equals(exceptId, StringComparison.Ordinal)
+                    || presence.NodeId is null
+                    || !presence.NodeId.Equals(nodeId, StringComparison.Ordinal))
+                {
+                    return;
+                }
+
+                if (!roster.TryGetValue(identity.Id, out var person))
+                {
+                    return;
+                }
+
+                if (requirePhone && !TalkCircles.HasPhone(person.Items))
+                {
+                    return;
+                }
+
+                list.Add(new TalkCircles.Candidate(
+                    identity.Id,
+                    roles.ClassId,
+                    !activity.IsActive && !school.TalkCircleByPerson.ContainsKey(identity.Id),
+                    school.TalkCircleByPerson.ContainsKey(identity.Id),
+                    TalkCircles.HasPhone(person.Items)));
+            });
+
+        return list.Where(candidate => candidate.IsIdle).ToArray();
+    }
+
+    private static void Register(School school, ActiveTalkCircle circle, ActionDef action)
+    {
+        school.TalkCirclesById[circle.Id] = circle;
+        foreach (var member in circle.Members)
+        {
+            school.TalkCircleByPerson[member] = circle.Id;
+            SetActivity(school, member, action.DefName, circle.TopicId, circle.RemainingMinutes);
+        }
+    }
+
+    private static void SetActivity(School school, string personId, string actionId, string topicId, float remaining)
+    {
+        school.World.Query(
+            in People,
+            (ref PersonIdentity identity, ref PersonActivity activity) =>
+            {
+                if (identity.Id.Equals(personId, StringComparison.Ordinal))
+                {
+                    activity = new PersonActivity(actionId, topicId, remaining);
+                }
+            });
+    }
+
+    private static void SyncActivity(School school, ActiveTalkCircle circle)
+    {
+        foreach (var member in circle.Members)
+        {
+            SetActivity(school, member, circle.ActionId, circle.TopicId, Math.Max(0f, circle.RemainingMinutes));
+        }
+    }
+
+    private static void Finish(School school, ActiveTalkCircle circle)
+    {
+        var catalog = school.Catalog!;
+        var rules = catalog.BehaviorRules;
+        var roster = school.Roster!;
+        var people = circle.Members
+            .Select(id => roster.People.First(person => person.Id.Equals(id, StringComparison.Ordinal)))
+            .ToArray();
+        if (!catalog.Topics.TryGetValue(circle.TopicId, out var topic))
+        {
+            topic = catalog.Topics.Values.First(def => !def.Abstract);
+        }
+
+        if (!catalog.Actions.TryGetValue(circle.ActionId, out var action))
+        {
+            action = catalog.Actions[TalkActions.Chat];
+        }
+
+        var hours = action.Minutes / 60f;
+        var sharedLanguage = TalkCircles.SharedLanguage(catalog, people, rules) is not null;
+        var language = TalkCircles.SharedLanguage(catalog, people, rules);
+
+        foreach (var person in people)
+        {
+            if (!string.IsNullOrWhiteSpace(action.Need)
+                && catalog.Needs.TryGetValue(action.Need, out var need))
+            {
+                var current = NeedOf(school, person.Id, action.Need);
+                if (float.IsNaN(current))
+                {
+                    current = need.Min;
+                }
+
+                var next = ActionStepper.ApplyNeedGain(current, action, need);
+                MutateNeed(school, person.Id, action.Need, next);
+            }
+
+            if (catalog.Skills.TryGetValue("Communication", out var communicationSkill))
+            {
+                var level = SkillOf(school, person.Id, "Communication");
+                var next = TalkCircles.CommunicationGain(level, communicationSkill, hours, rules);
+                MutateSkill(school, person.Id, "Communication", next);
+            }
+
+            if (language is not null
+                && catalog.Skills.TryGetValue(language, out var languageSkill)
+                && SkillOf(school, person.Id, language) < languageSkill.Range.Max)
+            {
+                var level = SkillOf(school, person.Id, language);
+                var next = TalkCircles.LanguageGain(level, languageSkill, hours, rules);
+                MutateSkill(school, person.Id, language, next);
+            }
+
+            foreach (var other in people)
+            {
+                if (other.Id.Equals(person.Id, StringComparison.Ordinal))
+                {
+                    continue;
+                }
+
+                var communication = SkillOf(school, person.Id, "Communication");
+                var appearance = AppearanceOf(school, other);
+                var delta = TalkCircles.OpinionDelta(
+                    person,
+                    other,
+                    topic,
+                    communication,
+                    sharedLanguage,
+                    circle.ActionId,
+                    appearance,
+                    rules,
+                    catalog);
+                if (delta == 0)
+                {
+                    continue;
+                }
+
+                var current = OpinionStore.Get(person, other.Id) ?? 0;
+                OpinionStore.Set(person, other.Id, current + delta);
+            }
+
+            school.AppendDayLog(new PersonLogEvent(
+                person.Id,
+                school.Clock.Time,
+                PersonLogTypes.TalkEnded,
+                circle.TopicId));
+        }
+
+        foreach (var member in circle.Members)
+        {
+            school.TalkCircleByPerson.Remove(member);
+            ClearActivity(school, member);
+        }
+
+        school.TalkCirclesById.Remove(circle.Id);
+    }
+
+    private static ApparelIssue AppearanceOf(School school, Person person)
+    {
+        var schoolClass = person.ClassId is { } classId
+            ? school.Roster!.Classes.FirstOrDefault(row => row.Id.Equals(classId, StringComparison.Ordinal))
+            : null;
+        var mode = ApparelPresence.ModeAt(school, person, schoolClass);
+        return ApparelDresser.CurrentIssues(school, person, mode);
+    }
+
+    private static float NeedOf(School school, string personId, string need)
+    {
+        var value = float.NaN;
+        school.World.Query(in People, (ref PersonIdentity identity, ref PersonNeeds needs) =>
+        {
+            if (identity.Id.Equals(personId, StringComparison.Ordinal))
+            {
+                value = needs.Values.GetValueOrDefault(need, float.NaN);
+            }
+        });
+        return value;
+    }
+
+    private static float SkillOf(School school, string personId, string skill)
+    {
+        var value = 0f;
+        school.World.Query(in People, (ref PersonIdentity identity, ref PersonSkills skills) =>
+        {
+            if (identity.Id.Equals(personId, StringComparison.Ordinal))
+            {
+                value = skills.Values.GetValueOrDefault(skill);
+            }
+        });
+        return value;
+    }
+
+    private static void MutateSkill(School school, string personId, string skill, float value)
+    {
+        school.World.Query(in People, (ref PersonIdentity identity, ref PersonSkills skills) =>
+        {
+            if (identity.Id.Equals(personId, StringComparison.Ordinal))
+            {
+                skills.Values[skill] = value;
+            }
+        });
+    }
+
+    private static void MutateNeed(School school, string personId, string need, float value)
+    {
+        school.World.Query(in People, (ref PersonIdentity identity, ref PersonNeeds needs) =>
+        {
+            if (identity.Id.Equals(personId, StringComparison.Ordinal))
+            {
+                needs.Values[need] = value;
+            }
+        });
+    }
+
+    private static void ClearActivity(School school, string personId)
+    {
+        school.World.Query(in People, (ref PersonIdentity identity, ref PersonActivity activity) =>
+        {
+            if (identity.Id.Equals(personId, StringComparison.Ordinal))
+            {
+                activity = PersonActivity.Idle;
+            }
+        });
+    }
+}