p54: 当日任务玩家可见与可完成——Kernel 状态机接入真实事件/环境信号（接受/对话/交易/到达/夜水边），HUD 短中文反馈 + 任务面板接受提示 + v3 任务态往返与 save(None) 兼容 + LV_P54_SHOT 证据

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diff --git a/src/LivingVillage.Desktop/TaskRuntime.fs b/src/LivingVillage.Desktop/TaskRuntime.fs
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+namespace LivingVillage.Desktop
+
+open LivingVillage.Kernel
+
+/// P54 职业切片三：把 Kernel 的当日任务状态机接到 Desktop 运行时（玩家可见 / 可完成）。
+///
+/// 全部为纯函数：接受任务、按**真实世界事件/信号**推进、给出短中文反馈。
+/// 完成判定只复用 Kernel 既有 `Occupation.advanceTask` / `applySignal`
+/// （其内部是 `satisfiesCompletion`），绝不按日历索引硬编码计数。
+module TaskRuntime =
+
+    let private completionMessage (before: Occupation.DailyTask option) (after: Occupation.DailyTask option) : string option =
+        match before, after with
+        | Some previous, Some current when previous.State = Occupation.Active && current.State = Occupation.Done ->
+            Some(sprintf "任务完成：%s" (Occupation.taskNameOf current.TemplateId))
+        | _ -> None
+
+    /// 接受当日任务（Offered → Active）；无任务 / 已在进行 / 终态时无变化、无反馈。
+    let accept (state: Occupation.State) : Occupation.State * string option =
+        match state.Today with
+        | Some task when task.State = Occupation.Offered ->
+            { state with Today = Some { task with State = Occupation.Active } },
+            Some(sprintf "已接受任务：%s" (Occupation.taskNameOf task.TemplateId))
+        | _ -> state, None
+
+    /// 用一条既有世界事件推进当日任务；Active → Done 时返回短中文反馈。
+    let advanceWithEvent (event: Sim.InteractionEvent) (state: Occupation.State) : Occupation.State * string option =
+        let before = state.Today
+        let next = Occupation.advanceTask event state
+        next, completionMessage before next.Today
+
+    /// 用一条已折叠的任务信号（到达瓦片 / 观察 / 夜在水边）推进当日任务。
+    let advanceWithSignal (signal: Occupation.TaskSignal) (state: Occupation.State) : Occupation.State * string option =
+        match state.Today with
+        | Some task ->
+            let after = Occupation.applySignal signal task
+            { state with Today = Some after }, completionMessage (Some task) (Some after)
+        | None -> state, None
+
+    /// 折叠多条信号（后面的不覆盖已得到的完成反馈）。
+    let foldSignals (signals: Occupation.TaskSignal list) (state: Occupation.State) : Occupation.State * string option =
+        signals
+        |> List.fold
+            (fun (current, found) signal ->
+                let next, message = advanceWithSignal signal current
+                next, (match found with Some _ -> found | None -> message))
+            (state, None)
+
+    /// 由真实世界环境折叠出的任务信号：跨瓦片 → 到达；夜 + 水边 → 夜在水边。
+    /// `previousTile = None`（尚未建立基线）时不产生到达信号，避免开局即误判完成。
+    let environmentSignals
+        (isNight: bool)
+        (nearWater: bool)
+        (previousTile: (int * int) option)
+        (tile: int * int)
+        : Occupation.TaskSignal list =
+        [ if previousTile.IsSome && previousTile.Value <> tile then yield Occupation.ArrivedAt tile
+          if isNight && nearWater then yield Occupation.NightAtWater ]
+
+    /// 比较两份职业状态，返回本次推进是否让当日任务完成（供交易等路径复用）。
+    let completedMessage (before: Occupation.State option) (after: Occupation.State option) : string option =
+        completionMessage
+            (before |> Option.bind (fun state -> state.Today))
+            (after |> Option.bind (fun state -> state.Today))