merge: P27 Rumor 长局成本修复（去装箱扫描 + O(1) 裁剪 + rumor-bench）— Hermes 复验通过

9 files changed, 260 insertions, 15 deletions

diff --git a/docs/维护说明.md b/docs/维护说明.md
index cc3a698..dbbf2ac 100644
--- a/docs/维护说明.md
+++ b/docs/维护说明.md
@@ -459,6 +459,57 @@ dotnet src/LivingVillage.Headless/bin/Release/net8.0/LivingVillage.Headless.dll
   各出一格，相邻民居极近时挑檐可能视觉叠压，可在布点时加 1 格间隔；③ 巡游 40s 档的 `visible>=8`
   占比仅 13%（P25 150s 档为 74%），属取证时长差异，非可见性回归。
 
+## P27：Rumor 长局性能修复（工作集扫描去装箱 + 裁剪判定）
+
+- **现状复核（更正 M3-1 前提）**：M3-1 记录的「`World.Rumors` 不裁剪、逐次聊天全表扫描」已由 M6a
+  （`d94ec2d` 工作集容量上界+按天淘汰、`cc850bf` 窗口化早停扫描）修复：`RumorEvent.DayIndex` 派生字段
+  + `trimRumors` 把工作集按「最新在前 + 3 天保留窗口」收敛。实测单日成本已平稳（本机 `--cost-probe`：
+  1 天 18.7s/18.9GB、5 天 90.5s/95.7GB、10 天 198.2s/191.9GB，≈19GB/天常数），M3 记录的 20 天
+  ≈45 s/天的超线性项已消失。故 P27 不采用「砍 depth/strength 传播」这类会改变模拟语义的方案。
+- **剩余 Rumor 成本定位**：工作集有界后每次聊天仍有两条 O(N) 扫描 `latestRumorFor` / `rumorIsDuplicate`；
+  且此前用 `=` 比较 `[<Struct>]` 的 `NpcId`/`RumorId`，会走泛型结构相等，对每一条被扫描到的谣言
+  装箱（实测 ≈24 B/条、单次聊天随 N 线性增长——`Sim.chat` 单独测得 N=16000 时 393,736 B/次）；
+  这是 Rumor 逐条分配的主因，而非列表 cons 本身。
+- **Kernel 长跑基准**：新增 `src/LivingVillage.Kernel/RumorBench.fs` 与 headless
+  `--rumor-bench [days npcs chats_per_day]`，把「聊天→生成/追溯谣言」路径从 `Sim.step` 的 NPC 快照
+  分配解耦，按模拟日推进 tick、固定节奏注入聊天，测工作集分配与耗时；同 `Config` 的
+  `retained_id_checksum` 可证明确定性。
+  修复前（30 NPC，`--rumor-bench D 30 2000`）：
+
+  | days | chat_calls | rumors_retained | allocated_bytes | elapsed_ms |
+  |---|---|---|---|---|
+  | 3 | 6000 | 6000 | 930,716,456 | 1626.7 |
+  | 30 | 60000 | 8000 | 13,419,045,864 | 12182.5 |
+  | 60 | 120000 | 8000 | 27,297,668,608 | 23769.7 |
+
+  60 天工作集稳定在 8000（M6a 的 3 天保留窗口 + 2000/天），不再随年龄增长。
+- **修复策略（两条，均不改保留集合与查询结果）**：
+  1. **扫描去装箱**：`latestRumorFor` / `rumorIsDuplicate` 原来用 `=` 比较 `[<Struct>]` 的
+     `NpcId`/`RumorId`（含 `RumorId option`），走泛型结构相等、逐条装箱。改为先解构底层
+     `int`/`int64` 再比较（`Parent` 用 `int64 option` 比较）；语义完全等价，扫描不再逐条分配。
+  2. **裁剪判定 O(1)**：`World` 新增派生镜像 `RumorCount`/`RumorOldestDay`（不参与存档，读档由
+     `Sim.rumorWorkingSetStats` 从列表重建）。`appendRumor` 用「`count+1 > capacity` 或
+     `min(oldest, day) < cutoff`」O(1) 判定；旧 `consRumor` 每次追加都 `rumorsNeedTrim` 全表扫一遍。
+     判定条件与 `rumorsNeedTrim` 逐字等价，仅真需裁剪时才走 `trimRumors`，保留集合逐条相同。
+- **修复后基准（同机、同 `--rumor-bench D 30 2000`）**：
+
+  | days | 修复前 alloc / ms | 修复后 alloc / ms | alloc 降幅 |
+  |---|---|---|---|
+  | 3 | 930,716,456 / 1626.7 | 482,716,192 / 1511.3 | −48% |
+  | 30 | 13,419,045,864 / 12182.5 | 4,884,067,640 / 8879.6 | −64% |
+  | 60 | 27,297,668,608 / 23769.7 | 9,774,660,360 / 17078.2 | −64% |
+
+  60 天分配 −64%、耗时 −28%；`retained_id_checksum=927964000`（3/30/60 天分别为
+  17997000 / 447996000 / 927964000）与修复前逐位一致，证明保留集合未变。
+- **等价性与门槛**：5 天 2000 聊天/天连跑两遍 `WorldSave.save` 逐字节相同；
+  `RumorCount`/`RumorOldestDay` 与对列表重算一致（count=8000、oldest_day=1）。
+  `final_digest=953775FAEB2FDDE97289491AA260BD8D390C571E48A7A13AD2CB6FB7124F7F6C`
+  三次一致、`performance_determinism=PASS`；Kernel 92 / Desktop 143 全绿。
+- **全模拟口径（`--cost-probe`）**：1 天 18.7s/18.8GB、5 天 90.4s/94.6GB，与修复前基本持平——
+  全模拟分配由逐 tick 的 `Npc[30]` 快照（`Sim.step` 的 `Array.copy`，≈120 B/NPC/tick）主导，
+  谣言子系统占比很小；P27 的收益集中在 Rumor 工作集路径，符合「隔离测量」的基准口径。
+  逐 tick NPC 快照分配属另一个课题（会触及不可变快照不变量），留给后续单。
+
 ## 已验证命令
 
 ```bash
@@ -477,6 +528,10 @@ LV_BATCH_WORKERS=4 dotnet src/LivingVillage.Headless/bin/Release/net8.0/LivingVi
 # 长局成本阶梯（只读，真实测量）
 dotnet src/LivingVillage.Headless/bin/Release/net8.0/LivingVillage.Headless.dll --cost-probe 1,5,10
 
+# P27 Rumor 长跑基准（隔离谣言子系统；默认 30 NPC×60 天×2000 聊天/天）
+dotnet src/LivingVillage.Headless/bin/Release/net8.0/LivingVillage.Headless.dll --rumor-bench
+dotnet src/LivingVillage.Headless/bin/Release/net8.0/LivingVillage.Headless.dll --rumor-bench 3 30 2000
+
 # 素材再生成（确定性，输出 byte-identical）
 python3 scripts/make-jiangnan-art.py && python3 scripts/make-cc0-art.py
 
diff --git a/src/LivingVillage.Headless/Program.fs b/src/LivingVillage.Headless/Program.fs
index 89f4f26..7f5dcf5 100644
--- a/src/LivingVillage.Headless/Program.fs
+++ b/src/LivingVillage.Headless/Program.fs
@@ -518,6 +518,28 @@ let runCostProbe (ladder: int64 list) : int =
         Console.Out.Flush()
     0
 
+/// `--rumor-bench [days] [npcs] [chats_per_day]`：Kernel 层 Rumor 长跑基准
+/// （默认 30 NPC × 60 模拟日 × 每日 2000 次聊天）。只读、不改模拟语义。
+let runRumorBench (argv: string[]) : int =
+    let tryInt64 (index: int) =
+        if argv.Length > index then
+            match Int64.TryParse argv.[index] with
+            | true, value -> Some value
+            | _ -> None
+        else None
+    let days = tryInt64 1 |> Option.defaultValue RumorBench.defaultConfig.Days
+    let npcs = tryInt64 2 |> Option.defaultValue (int64 RumorBench.defaultConfig.NpcCount) |> int
+    let chatsPerDay = tryInt64 3 |> Option.defaultValue (int64 RumorBench.defaultConfig.ChatsPerDay) |> int
+    let config =
+        { RumorBench.defaultConfig with
+            Days = days
+            NpcCount = npcs
+            ChatsPerDay = chatsPerDay }
+    let result = RumorBench.run config
+    printfn "%s" (RumorBench.format result)
+    Console.Out.Flush()
+    0
+
 let runExisting (argv: string[]) =
     let rec parse
         (i: int)
@@ -581,7 +603,7 @@ let runExisting (argv: string[]) =
             if stats.NonFinite > 0L || stats.OutOfBounds > 0L || not replayOk then 1 else 0
     | Error msg ->
         eprintfn $"headless: {msg}"
-        eprintfn "usage: dotnet run -c Release --project src/LivingVillage.Headless -- --days N --seed S [--npc N] [--dump-relations] [--dump-rumors] [--replay-rumors] | --m5-smoke | --m6a-smoke | --batch K D | --performance-baseline | --cost-probe [D1,D2,...]"
+        eprintfn "usage: dotnet run -c Release --project src/LivingVillage.Headless -- --days N --seed S [--npc N] [--dump-relations] [--dump-rumors] [--replay-rumors] | --m5-smoke | --m6a-smoke | --batch K D | --performance-baseline | --cost-probe [D1,D2,...] | --rumor-bench [days npcs chats_per_day]"
         2
 
 let private parseCostLadder (argv: string[]) : int64 list =
@@ -608,5 +630,7 @@ let main argv =
         LivingVillage.Headless.PerformanceProbe.runDefault ()
     elif argv.Length >= 1 && argv.[0] = "--cost-probe" then
         runCostProbe (parseCostLadder argv)
+    elif argv.Length >= 1 && argv.[0] = "--rumor-bench" then
+        runRumorBench argv
     else
         runExisting argv
diff --git a/src/LivingVillage.Kernel.Tests/RelationTests.fs b/src/LivingVillage.Kernel.Tests/RelationTests.fs
index b98252d..1a6d178 100644
--- a/src/LivingVillage.Kernel.Tests/RelationTests.fs
+++ b/src/LivingVillage.Kernel.Tests/RelationTests.fs
@@ -47,6 +47,8 @@ module RelationHarness =
           Npcs = [| mkNpc 0 mem0; mkNpc 1 mem1 |]
           Events = []
           Rumors = []
+          RumorCount = 0
+          RumorOldestDay = System.Int64.MaxValue
           Annals = [] }
 
     let chatted (tick: int64) (partner: int) : MemoryEvent =
@@ -208,6 +210,8 @@ type RelationTests () =
               Npcs = [| self; nearest; alternate |]
               Events = []
               Rumors = []
+              RumorCount = 0
+              RumorOldestDay = System.Int64.MaxValue
               Annals = [] }
         let next = Sim.step RelationHarness.zeroInput world
         match List.tryHead next.Npcs.[0].Mind.Memory with
diff --git a/src/LivingVillage.Kernel.Tests/RumorTests.fs b/src/LivingVillage.Kernel.Tests/RumorTests.fs
index 2cbb189..e8cf07a 100644
--- a/src/LivingVillage.Kernel.Tests/RumorTests.fs
+++ b/src/LivingVillage.Kernel.Tests/RumorTests.fs
@@ -52,6 +52,8 @@ module private RumorHarness =
           Npcs = Array.init count npc
           Events = []
           Rumors = []
+          RumorCount = 0
+          RumorOldestDay = System.Int64.MaxValue
           Annals = [] }
 
     let readyForChat (world: World) : World =
diff --git a/src/LivingVillage.Kernel.Tests/TradeTests.fs b/src/LivingVillage.Kernel.Tests/TradeTests.fs
index 77e5658..fa40ac3 100644
--- a/src/LivingVillage.Kernel.Tests/TradeTests.fs
+++ b/src/LivingVillage.Kernel.Tests/TradeTests.fs
@@ -56,6 +56,8 @@ module private TradeHarness =
                  npc 1 sellerMoney sellerHunger sellerFood sellerMemory None |]
           Events = []
           Rumors = []
+          RumorCount = 0
+          RumorOldestDay = System.Int64.MaxValue
           Annals = [] }
 
     let request quantity =
diff --git a/src/LivingVillage.Kernel/LivingVillage.Kernel.fsproj b/src/LivingVillage.Kernel/LivingVillage.Kernel.fsproj
index c6b3bf9..72e5def 100644
--- a/src/LivingVillage.Kernel/LivingVillage.Kernel.fsproj
+++ b/src/LivingVillage.Kernel/LivingVillage.Kernel.fsproj
@@ -7,6 +7,7 @@
   <ItemGroup>
     <Compile Include="Rng.fs" />
     <Compile Include="Sim.fs" />
+    <Compile Include="RumorBench.fs" />
     <Compile Include="Occupation.fs" />
     <Compile Include="SimulationControl.fs" />
     <Compile Include="WorldSave.fs" />
diff --git a/src/LivingVillage.Kernel/RumorBench.fs b/src/LivingVillage.Kernel/RumorBench.fs
new file mode 100644
index 0000000..145f92c
--- /dev/null
+++ b/src/LivingVillage.Kernel/RumorBench.fs
@@ -0,0 +1,109 @@
+namespace LivingVillage.Kernel
+
+open System
+open System.Diagnostics
+open LivingVillage.Kernel.Sim
+
+/// Kernel 层 Rumor 长跑基准：把「聊天 → 生成/追溯传闻」这条路径单独拎出来，按
+/// 模拟日推进 tick 并注入固定节奏的聊天，长期测量 Rumor 工作集随世界年龄的
+/// 分配与耗时量级（与 `Sim.step` 的 NPC 快照分配解耦，便于隔离谣言子系统）。
+///
+/// 该基准只读、不改变任何模拟语义；所有输入由 `Config` 决定，无墙钟/`System.Random`，
+/// 同一 `Config` 两次运行产生相同的工作集校验和。
+module RumorBench =
+
+    type Config =
+        { Seed: uint64
+          NpcCount: int
+          Days: int64
+          /// 每个模拟日注入的聊天次数（决定谣言产生速率）。
+          ChatsPerDay: int }
+
+    type Result =
+        { Seed: uint64
+          NpcCount: int
+          Days: int64
+          ChatsPerDay: int
+          ChatCalls: int64
+          RumorsCreated: int64
+          RumorsRetained: int
+          /// 保留工作集内各条目 Id 之和，用于证明同一 Config 的确定性。
+          RetainedIdChecksum: int64
+          AllocatedBytes: int64
+          ElapsedMs: float }
+
+    /// 任务默认口径：30 NPC × 60 模拟日 × 每日 2000 次聊天。
+    let defaultConfig : Config =
+        { Seed = 42UL
+          NpcCount = 30
+          Days = 60L
+          ChatsPerDay = 2000 }
+
+    /// 测试/快速核验口径（同样是 30 NPC，但只跑 3 天）。
+    let quickConfig : Config =
+        { defaultConfig with Days = 3L }
+
+    let private resetParticipants (ids: NpcId list) (world: World) : World =
+        let npcs = Array.copy world.Npcs
+        for id in ids do
+            let (NpcId index) = id
+            if index >= 0 && index < npcs.Length then
+                npcs.[index] <-
+                    { npcs.[index] with
+                        Mind = { npcs.[index].Mind with Action = Wander } }
+        { world with Npcs = npcs }
+
+    let private retainedChecksum (rumors: RumorEvent list) : int64 =
+        rumors |> List.sumBy (fun rumor -> let (RumorId id) = rumor.Id in id)
+
+    let run (config: Config) : Result =
+        if config.NpcCount < 2 then invalidArg (nameof config) "NpcCount must be at least 2"
+        if config.Days <= 0L then invalidArg (nameof config) "Days must be positive"
+        if config.ChatsPerDay <= 0 then invalidArg (nameof config) "ChatsPerDay must be positive"
+        if config.ChatsPerDay > 1000000 then invalidArg (nameof config) "ChatsPerDay is too large"
+        let callsPerDay = int64 config.ChatsPerDay
+        let ticksPerCall = max 1L (ticksPerDay / callsPerDay)
+        let totalCalls = config.Days * callsPerDay
+        let mutable world = Sim.initialWorldN config.Seed config.NpcCount
+        let mutable created = 0L
+        let mutable calls = 0L
+        GC.Collect(2, GCCollectionMode.Forced, true, true)
+        GC.WaitForPendingFinalizers()
+        GC.Collect(2, GCCollectionMode.Forced, true, true)
+        let allocatedBefore = GC.GetAllocatedBytesForCurrentThread()
+        let stopwatch = Stopwatch.StartNew()
+        for i in 0L .. totalCalls - 1L do
+            let dayIndex = i / callsPerDay
+            let within = i % callsPerDay
+            let tick = dayIndex * ticksPerDay + within * ticksPerCall
+            let narratorIndex = int (i % int64 config.NpcCount)
+            let receiverIndex =
+                int ((i + 1L + (i / int64 config.NpcCount) % int64 (config.NpcCount - 1)) % int64 config.NpcCount)
+            let narrator = NpcId narratorIndex
+            let receiver = NpcId receiverIndex
+            world <-
+                resetParticipants [ narrator; receiver ] { world with Tick = tick }
+            match Sim.chat { Narrator = narrator; Receiver = receiver } world with
+            | ChatSucceeded (rumor, next) ->
+                world <- next
+                calls <- calls + 1L
+                if rumor.IsSome then created <- created + 1L
+            | ChatRejected _ -> ()
+        stopwatch.Stop()
+        let allocatedAfter = GC.GetAllocatedBytesForCurrentThread()
+        { Seed = config.Seed
+          NpcCount = config.NpcCount
+          Days = config.Days
+          ChatsPerDay = config.ChatsPerDay
+          ChatCalls = calls
+          RumorsCreated = created
+          RumorsRetained = world.Rumors.Length
+          RetainedIdChecksum = retainedChecksum world.Rumors
+          AllocatedBytes = allocatedAfter - allocatedBefore
+          ElapsedMs = stopwatch.Elapsed.TotalMilliseconds }
+
+    let format (result: Result) : string =
+        sprintf
+            "rumor_bench seed=%d npcs=%d days=%d chats_per_day=%d chat_calls=%d rumors_created=%d rumors_retained=%d retained_id_checksum=%d allocated_bytes=%d elapsed_ms=%.3f"
+            result.Seed result.NpcCount result.Days result.ChatsPerDay result.ChatCalls result.RumorsCreated
+            result.RumorsRetained result.RetainedIdChecksum result.AllocatedBytes result.ElapsedMs
diff --git a/src/LivingVillage.Kernel/Sim.fs b/src/LivingVillage.Kernel/Sim.fs
index cedadfa..5c4e107 100644
--- a/src/LivingVillage.Kernel/Sim.fs
+++ b/src/LivingVillage.Kernel/Sim.fs
@@ -192,6 +192,12 @@ module Sim =
           Npcs: Npc[]
           Events: InteractionEvent list
           Rumors: RumorEvent list
+          /// 派生镜像：工作集条数（= Rumors.Length）。不参与存档序列化，读档由列表重建；
+          /// 用于把每追加一条都要全表扫描的裁剪判定降为 O(1)。
+          RumorCount: int
+          /// 派生镜像：工作集内最小 DayIndex（空表为 Int64.MaxValue）。语义等价于
+          /// `rumorsNeedTrim` 的「存在早于保留窗口的条目」判定。
+          RumorOldestDay: int64
           Annals: AnnalEntry list }
 
     type DialogueFailure =
@@ -481,6 +487,8 @@ module Sim =
           Npcs = [| npc |]
           Events = []
           Rumors = []
+          RumorCount = 0
+          RumorOldestDay = System.Int64.MaxValue
           Annals = [] }
 
     let initialWorldN (seed: uint64) (count: int) : World =
@@ -680,19 +688,49 @@ module Sim =
         else
             rumors
 
-    /// 追加一条谣言并顺手裁剪工作集；容量内且新鲜时等价于 `rumor :: rumors`。
-    let private consRumor (nowTick: int64) (rumor: RumorEvent) (rumors: RumorEvent list) : RumorEvent list =
-        trimRumors nowTick (rumor :: rumors)
+    /// 工作集派生统计：(条数, 最小 DayIndex；空表为 Int64.MaxValue)。仅裁剪/读档等非热路径调用。
+    let rumorWorkingSetStats (rumors: RumorEvent list) : int * int64 =
+        rumors.Length,
+        (rumors |> List.fold (fun acc rumor -> min acc rumor.DayIndex) System.Int64.MaxValue)
+
+    let private oldestRumorDay (rumors: RumorEvent list) : int64 = snd (rumorWorkingSetStats rumors)
+
+    /// 追加一条谣言并维护派生元数据。容量内且新鲜时等价于 `rumor :: rumors`，且**不再全表扫描**
+    /// 判断是否需要裁剪（旧 `consRumor` 每次追加都会 `rumorsNeedTrim` 走一遍工作集）；
+    /// 仅当条数超容量或存在早于保留窗口的条目时才走 `trimRumors`，保留集合与旧实现逐条相同。
+    let private appendRumor (nowTick: int64) (rumor: RumorEvent) (world: World) : World =
+        let cutoffDay = max 0L (rumorDayIndex nowTick - rumorRetentionDays)
+        let nextCount = world.RumorCount + 1
+        let nextOldest = min world.RumorOldestDay rumor.DayIndex
+        if nextCount > rumorCapacity || nextOldest < cutoffDay then
+            let trimmed = trimRumors nowTick (rumor :: world.Rumors)
+            { world with
+                Rumors = trimmed
+                RumorCount = trimmed.Length
+                RumorOldestDay = oldestRumorDay trimmed }
+        else
+            { world with
+                Rumors = rumor :: world.Rumors
+                RumorCount = nextCount
+                RumorOldestDay = nextOldest }
+
+    /// `NpcId`/`RumorId` 是 `[<Struct>]` 单例判别联合：直接用 `=` 比较会走泛型结构相等并
+    /// 在每次比较时为两侧装箱（实测 ~24 B/次）。在按 tick 全表扫描的热路径里逐条比较，
+    /// 这是 Rumor 分配的主要来源。这里改为先解构出底层 int/int64 再比较（语义完全等价，
+    /// 仅去掉装箱），扫描不再产生逐条分配。
+    let inline private npcIdValue (NpcId id) : int = id
+    let inline private rumorIdValue (RumorId id) : int64 = id
 
     let private latestRumorFor (receiver: NpcId) (world: World) : RumorEvent option =
         // 工作集最新在前且 Tick 非递增：第一条命中的即“Tick 最大、Id 最大”，与原实现
         // （filter 后 sortByDescending 取头）等价；窗口外无分配提前返回。
+        let receiverId = npcIdValue receiver
         let rec loop (rest: RumorEvent list) : RumorEvent option =
             match rest with
             | [] -> None
             | rumor :: tail ->
                 if world.Tick - rumor.Tick > rumorFreshnessTicks then None
-                elif rumor.Receiver = receiver
+                elif npcIdValue rumor.Receiver = receiverId
                      && rumor.Tick <= world.Tick
                      && rumorStrengthAt world.Tick rumor >= rumorMinimumStrength then Some rumor
                 else loop tail
@@ -783,11 +821,13 @@ module Sim =
                 let avatarMemory = recordMemory world.Tick (Dialogue(target, intent, response)) world.Avatar.Mind.Memory
                 let event = { Tick = world.Tick; Kind = DialogueEvent outcome }
                 let updated =
-                    { world with
-                        Avatar = { world.Avatar with Mind = { world.Avatar.Mind with Memory = avatarMemory } }
-                        Npcs = newNpcs
-                        Events = world.Events @ [ event ]
-                        Rumors = consRumor world.Tick rumor world.Rumors }
+                    appendRumor
+                        world.Tick
+                        rumor
+                        { world with
+                            Avatar = { world.Avatar with Mind = { world.Avatar.Mind with Memory = avatarMemory } }
+                            Npcs = newNpcs
+                            Events = world.Events @ [ event ] }
                 let withRumorAnnal =
                     appendAnnal
                         { Tick = world.Tick
@@ -826,16 +866,21 @@ module Sim =
               RecentMemory = List.truncate 8 npc.Mind.Memory })
 
     let private rumorIsDuplicate (request: ChatRequest) (parent: RumorEvent option) (world: World) : bool =
-        let parentId = parent |> Option.map (fun rumor -> rumor.Id)
+        let parentId = parent |> Option.map (fun rumor -> rumorIdValue rumor.Id)
+        let narratorId = npcIdValue request.Narrator
+        let receiverId = npcIdValue request.Receiver
         // 窗口外条目强度必 < rumorMinimumStrength，与原全表 exists 等价；命中或越窗即无分配返回。
+        // `Parent` 用底层 int64 比较而非 `RumorId option` 结构相等，避免逐条装箱。
         let rec loop (rest: RumorEvent list) : bool =
             match rest with
             | [] -> false
             | rumor :: tail ->
                 if world.Tick - rumor.Tick > rumorFreshnessTicks then false
-                elif rumor.Narrator = request.Narrator
-                     && rumor.Receiver = request.Receiver
-                     && rumor.Parent = parentId
+                elif npcIdValue rumor.Narrator = narratorId
+                     && npcIdValue rumor.Receiver = receiverId
+                     && (match rumor.Parent with
+                         | Some parentRumor -> parentId = Some(rumorIdValue parentRumor)
+                         | None -> parentId.IsNone)
                      && rumor.Tick <= world.Tick
                      && rumorStrengthAt world.Tick rumor >= rumorMinimumStrength then true
                 else loop tail
@@ -936,7 +981,7 @@ module Sim =
                                 { npc with
                                     Mind = { npc.Mind with Memory = recordMemory world.Tick (Rumor rumor.Id) npc.Mind.Memory } }
                             { chatted with Npcs = newNpcs }
-                    let updated = { withReceiverRumor with Rumors = consRumor world.Tick rumor world.Rumors }
+                    let updated = appendRumor world.Tick rumor withReceiverRumor
                     ChatSucceeded(
                         Some rumor,
                         appendAnnal
diff --git a/src/LivingVillage.Kernel/WorldSave.fs b/src/LivingVillage.Kernel/WorldSave.fs
index f1b0be3..b3bdfa9 100644
--- a/src/LivingVillage.Kernel/WorldSave.fs
+++ b/src/LivingVillage.Kernel/WorldSave.fs
@@ -645,6 +645,7 @@ module WorldSave =
                 let events = List.init eventCount (fun index -> readInteraction reader (sprintf "event[%d]" index))
                 let rumorCount = readCount reader "rumors"
                 let rumors = List.init rumorCount (fun index -> readRumor reader (sprintf "rumor[%d]" index))
+                let rumorStats = rumorWorkingSetStats rumors
                 let annalCount = readCount reader "annals"
                 let annals = List.init annalCount (fun index -> readAnnal reader (sprintf "annal[%d]" index))
                 let todayTask =
@@ -667,6 +668,8 @@ module WorldSave =
                        Npcs = npcs
                        Events = events
                        Rumors = rumors
+                       RumorCount = fst rumorStats
+                       RumorOldestDay = snd rumorStats
                        Annals = annals },
                      occupation)
             with