diff --git a/AGENTS.md b/AGENTS.md
index 8104e82..16d6e7a 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -13,7 +13,8 @@ way; this file is *how to work in them*.
 | skills, traits, body, needs, name sets | `src/HSchool.Content` |
 | people generation, families, roster records, yearly intake | `src/HSchool.People` |
 | timetable planning | `src/HSchool.Schedule` |
-| people in a school's World, need decay | `src/HSchool.Simulation` |
+| routes, day plans, who comes today | `src/HSchool.Ai` |
+| people in a school's World, need decay, walking | `src/HSchool.Simulation` |
 | the menu API (list, create, delete, mods, catalog) and the people list/card | `src/HSchool.Server/Api` **and** `docs/protocol.md` |
 | what the socket carries | `src/HSchool.Protocol` **and** `src/HSchool.Client/src/net/protocol.ts` **and** `docs/protocol.md` |
 | connection handling, workers, saves | `src/HSchool.Server` |
@@ -111,6 +112,8 @@ say so explicitly in the change description.
   produce the same roster; the suite does not boot a host.
 - Timetable planning belongs in `tests/HSchool.Schedule.Tests`. Same staff, map and locks must
   produce the same table; the suite does not boot a host.
+- Walking and day plans belong in `tests/HSchool.Ai.Tests`. Same seed and map must produce the
+  same route and commute; the suite does not boot a host, and it does not reference Arch.
 - Catalog, inheritance, patches and map validation belong in `tests/HSchool.Content.Tests`.
   Feed the loader documents, not disk paths.
 - Protocol changes need a round-trip test **and** a byte-layout assertion on both sides.
@@ -164,3 +167,6 @@ say so explicitly in the change description.
   wrong for anything that must arrive exactly once — such a message would need its own path.
 - `erasableSyntaxOnly` is off in `tsconfig.app.json` on purpose: constructor parameter properties
   are used throughout.
+- **A large one-shot `Tick(week)` jumps the clock, then applies all those minutes at the new
+  time.** Presence equality tests must loop `FixedDeltaTime` or one game minute. `string.GetHashCode`
+  is randomized — commute slack goes through `Seed.Mix`, never that.
diff --git a/README.md b/README.md
index f52610c..4bd8b8b 100644
--- a/README.md
+++ b/README.md
@@ -121,6 +121,7 @@ Simulation tunables live under the `Simulation` section of
 | `MinSaveIntervalMilliseconds` | 1000 | shortest gap between saves caused by pause or speed |
 | `MonthlyPayrollCap` | 100000 | monthly payroll the player may commit; hires and assignments that would exceed it are rejected |
 | `SchoolWeekDays` | 5 | working days from Monday (5 is Mon–Fri; 6 adds Saturday) |
+| `MaxDecisionsPerTick` | 64 | presence decisions processed per tick; overflow waits |
 
 ## What is deliberately missing
 
diff --git a/docs/architecture.md b/docs/architecture.md
index 1eb1cdd..4b9cfb7 100644
--- a/docs/architecture.md
+++ b/docs/architecture.md
@@ -36,14 +36,15 @@ there is no UI on the server.
 | `src/HSchool.Content` | JSONC defs, inheritance, patches, locales, map instance and connectivity. No Arch, no ASP.NET. |
 | `src/HSchool.People` | Roster generation from catalog, map and seed. No Arch, no ASP.NET. |
 | `src/HSchool.Schedule` | Timetable from curriculum, assignments and map. No Arch, no ASP.NET. |
+| `src/HSchool.Ai` | Walk graph, day plans, duty rooms. No Arch, no ASP.NET, no `DateTime.Now`. |
 | `src/HSchool.Simulation` | Schools, the game clock, the Arch ECS world. Holds a frozen catalog and map; no HTTP. |
 | `src/HSchool.Server` | ASP.NET Core host: the menu API, the WebSocket endpoint, per-school workers, `mods/` and `saves/`. |
 | `src/HSchool.ServiceDefaults` | Shared Aspire wiring: OpenTelemetry, health checks, service discovery, resilience. |
 | `src/HSchool.AppHost` | Aspire orchestration: which resources run and how they find each other. |
 | `src/HSchool.Client` | Vite + TypeScript UI: main menu, creation form, the school screen. |
 
-Dependency direction is one-way: `Protocol ← Server → Simulation → People → Content`, and
-`Schedule → Content`. Nothing in `Simulation` or `Content` knows about HTTP, and nothing in
+Dependency direction is one-way: `Protocol ← Server → Simulation → Ai → People / Schedule → Content`.
+Nothing in `Simulation` or `Content` knows about HTTP, and nothing in
 `Protocol` knows about schools.
 
 ## Two channels, on purpose
@@ -80,7 +81,9 @@ touching a school itself.
 ## Schools
 
 A `School` is one save: an id, a name, a `GameClock`, a frozen catalog, a map, a roster and an
-Arch `World`. Pupils, staff and parents live in that world as entities; they do not walk yet.
+Arch `World`. Pupils, staff and parents live in that world as entities. Presence is a component:
+each person occupies a map node or is off campus. Empty-time skip jumps the clock to the next
+work morning when the campus is empty and the day frame is closed.
 
 `GameClock` moves while it is running, in fixed steps:
 `realSeconds × gameMinutesPerRealSecond × speedMultiplier`. At the defaults that is 5 game minutes
@@ -107,7 +110,7 @@ intake). Pause and speed changes are written
 too, but coalesced to at most one write per `MinSaveIntervalMilliseconds`: a client can send those
 as fast as the socket allows, and each one is a file write on the school's own thread. Shutdown
 always flushes, so a pause is never lost. The clock file also stores the
-mod pack ids and the map layout; the catalog is loaded again from `mods/` on start. A missing
+mod pack ids, the map layout and each person's place on that map; the catalog is loaded again from `mods/` on start. A missing
 mod folder, a map that no longer validates, or a roster that no longer fits the map leaves the
 files in place and that school unstarted.
 
diff --git a/docs/design/projects.md b/docs/design/projects.md
index 9cff5fa..d6a5df5 100644
--- a/docs/design/projects.md
+++ b/docs/design/projects.md
@@ -1,6 +1,6 @@
 # Нарезка проектов (целевая)
 
-Сейчас в коде: `Protocol ← Server → Simulation → People → Content`. Каталог не в Simulation (рядом с Arch)
+Сейчас в коде: `Protocol ← Server → Simulation → Ai → People / Schedule → Content`. Каталог не в Simulation (рядом с Arch)
 и не в Server (рядом с Kestrel) — парсер JSONC и проверка графа не знают, что такое tick.
 
 ## Зависимости
diff --git a/docs/phases/18-presence-walking.md b/docs/phases/18-presence-walking.md
index 5175212..a5592c0 100644
--- a/docs/phases/18-presence-walking.md
+++ b/docs/phases/18-presence-walking.md
@@ -12,61 +12,61 @@
 
 ## Задачи
 
-- [ ] Новый проект `HSchool.Ai` рядом с `People` и `Schedule`: зависит на `Content`, `People` и
+- [x] Новый проект `HSchool.Ai` рядом с `People` и `Schedule`: зависит на `Content`, `People` и
       `Schedule`, без Arch и ASP.NET. Рядом — `tests/HSchool.Ai.Tests`
-- [ ] `travelMinutes` на `RoomDef` и `TerritoryDef`; в `core` проставлены кабинет 0.5, коридор
+- [x] `travelMinutes` на `RoomDef` и `TerritoryDef`; в `core` проставлены кабинет 0.5, коридор
       1.5, лестница 1.5, вестибюль 1, двор 3
-- [ ] Маршрутизация по `MapLayout.Links` — в библиотеке: матрица следующих шагов считается
+- [x] Маршрутизация по `MapLayout.Links` — в библиотеке: матрица следующих шагов считается
       **один раз** при загрузке школы, не на каждом шаге
-- [ ] План дня человека — тоже в библиотеке: во сколько выходить, чтобы успеть, и когда уходить.
+- [x] План дня человека — тоже в библиотеке: во сколько выходить, чтобы успеть, и когда уходить.
       Часы, компоненты и мир туда не проникают
-- [ ] Место человека — компонент в `World`: узел, остаток пути, минуты до выхода из узла.
+- [x] Место человека — компонент в `World`: узел, остаток пути, минуты до выхода из узла.
       Человек всегда в узле; рёбер как состояний нет
-- [ ] Состояние «вне школы» — не удаление сущности: человек остаётся в списке и в карточке
-- [ ] Приход и уход: у кого сегодня нет уроков, тот не приходит вовсе. Ученик и учитель — по
+- [x] Состояние «вне школы» — не удаление сущности: человек остаётся в списке и в карточке
+- [x] Приход и уход: у кого сегодня нет уроков, тот не приходит вовсе. Ученик и учитель — по
       своим урокам, прочий штат — по дню школы
-- [ ] Запас на дорогу свой у каждого: путь от двора плюс несколько минут из своего потока
+- [x] Запас на дорогу свой у каждого: путь от двора плюс несколько минут из своего потока
       случайности, с поправкой на черты
-- [ ] Обязанность как место назначения: урок — кабинет из расписания, должность — комната из
+- [x] Обязанность как место назначения: урок — кабинет из расписания, должность — комната из
       `RoomDef.works`. Выбора действий пока нет
-- [ ] Движение по тику: остаток минут в узле уменьшается, при нуле человек переходит в следующий
+- [x] Движение по тику: остаток минут в узле уменьшается, при нуле человек переходит в следующий
       узел пути
-- [ ] Стабильный порядок обхода людей — собственный список, а не порядок сущностей в Arch
-- [ ] Адаптер в `HSchool.Simulation`: собирает значения из компонентов, зовёт библиотеку,
+- [x] Стабильный порядок обхода людей — собственный список, а не порядок сущностей в Arch
+- [x] Адаптер в `HSchool.Simulation`: собирает значения из компонентов, зовёт библиотеку,
       записывает ответ обратно. Горячий путь — движение — границу не пересекает
-- [ ] Ориентир в `AGENTS.md`, `docs/architecture.md` и `docs/design/projects.md` знает про новый
+- [x] Ориентир в `AGENTS.md`, `docs/architecture.md` и `docs/design/projects.md` знает про новый
       проект
-- [ ] Место, путь и назначение едут в файл часов; кого в файле нет, тот расставляется по
+- [x] Место, путь и назначение едут в файл часов; кого в файле нет, тот расставляется по
       обязанности
-- [ ] Потолок решений за тик — в `SimulationOptions`, как очередь, а не как отсечка
-- [ ] Предикат «школа пуста»: в здании и во дворе нет никого
-- [ ] Рабочее окно дня — от шести утра до последнего звонка по **каркасу дня**, а не по
+- [x] Потолок решений за тик — в `SimulationOptions`, как очередь, а не как отсечка
+- [x] Предикат «школа пуста»: в здании и во дворе нет никого
+- [x] Рабочее окно дня — от шести утра до последнего звонка по **каркасу дня**, а не по
       фактическому расписанию
-- [ ] «Ближайшее шесть утра рабочего дня впереди»: ночь ведёт в то же утро, вечер — в следующее,
+- [x] «Ближайшее шесть утра рабочего дня впереди»: ночь ведёт в то же утро, вечер — в следующее,
       выходные, праздники и каникулы пропускаются. Поиск ограничен разумным числом дней и
       честно отвечает «нет такого»
-- [ ] Прыжок часов туда одним шагом: разрешён только при пустой школе и вне рабочего окна,
+- [x] Прыжок часов туда одним шагом: разрешён только при пустой школе и вне рабочего окна,
       отрабатывает первое сентября и обновление пула за весь пропуск, после себя пишет сейв
 
 ## Тесты, без которых фаза не закрыта
 
-- [ ] Путь из кабинета 201 в санузел первого этажа идёт через лестницу и коридор, а не напрямую
-- [ ] Сумма `travelMinutes` совпадает с временем, за которое человек реально доходит
-- [ ] В воскресенье и в каникулы школа пуста: все вне школы
-- [ ] Класс без уроков сегодня не приходит, а его учитель с уроками у другого класса — приходит
-- [ ] К началу первого урока ученик находится в своём кабинете
-- [ ] Физкультура после урока в главном корпусе: класс доходит до спортзала, и видно, что
+- [x] Путь из кабинета 201 в санузел первого этажа идёт через лестницу и коридор, а не напрямую
+- [x] Сумма `travelMinutes` совпадает с временем, за которое человек реально доходит
+- [x] В воскресенье и в каникулы школа пуста: все вне школы
+- [x] Класс без уроков сегодня не приходит, а его учитель с уроками у другого класса — приходит
+- [x] К началу первого урока ученик находится в своём кабинете
+- [x] Физкультура после урока в главном корпусе: класс доходит до спортзала, и видно, что
       перемены на это едва хватает
-- [ ] Тот же сид и та же карта дают то же расположение людей на тот же момент
-- [ ] Сохранение и загрузка посреди перемены не телепортируют людей
-- [ ] Прыжок с субботы попадает в понедельник, 6:00; с трёх ночи вторника — в утро того же
+- [x] Тот же сид и та же карта дают то же расположение людей на тот же момент
+- [x] Сохранение и загрузка посреди перемены не телепортируют людей
+- [x] Прыжок с субботы попадает в понедельник, 6:00; с трёх ночи вторника — в утро того же
       вторника; с десяти вечера — в утро среды
-- [ ] Прыжок в учебное время отклоняется. В семь утра рабочего дня, когда школа ещё пуста, —
+- [x] Прыжок в учебное время отклоняется. В семь утра рабочего дня, когда школа ещё пуста, —
       тоже: это уже рабочее окно
-- [ ] У школы без единого учителя рабочий день не пропускается
-- [ ] Прыжок через летние каникулы проводит первое сентября: классы перешли, выпуск состоялся,
+- [x] У школы без единого учителя рабочий день не пропускается
+- [x] Прыжок через летние каникулы проводит первое сентября: классы перешли, выпуск состоялся,
       набор пришёл
-- [ ] Промотанная неделя и прожитая неделя дают одно состояние школы
+- [x] Промотанная неделя и прожитая неделя дают одно состояние школы
 
 ## Критерий готовности
 
diff --git a/docs/phases/README.md b/docs/phases/README.md
index fbcd084..6d6ddc2 100644
--- a/docs/phases/README.md
+++ b/docs/phases/README.md
@@ -82,7 +82,7 @@
 
 | Фаза | Статус | Зачем |
 | --- | --- | --- |
-| [18. Присутствие и ходьба](18-presence-walking.md) | ⬜ | `HSchool.Ai`, место человека, маршруты, приход и уход |
+| [18. Присутствие и ходьба](18-presence-walking.md) | ✅ | `HSchool.Ai`, место человека, маршруты, приход и уход |
 | [19. Присутствие на экране](19-presence-screen.md) | ⬜ | Своё сообщение ~2 Гц, числа в дереве, статический снимок карты, пропуск пустого времени |
 
 **Этап B — поведение.** Появляются нужды, действия и выбор между ними и обязанностью.
diff --git a/h-school.sln b/h-school.sln
index 50249d9..f891b5a 100644
--- a/h-school.sln
+++ b/h-school.sln
@@ -35,6 +35,10 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "HSchool.Schedule", "src\HSc
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "HSchool.Schedule.Tests", "tests\HSchool.Schedule.Tests\HSchool.Schedule.Tests.csproj", "{85FF85BD-F572-4F0A-A11E-FA855D480C1D}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "HSchool.Ai", "src\HSchool.Ai\HSchool.Ai.csproj", "{C21FB23F-F131-4651-8236-4F3E076B40BF}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "HSchool.Ai.Tests", "tests\HSchool.Ai.Tests\HSchool.Ai.Tests.csproj", "{C355307C-D7D3-48C7-9615-CB5FBCF83D49}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -213,6 +217,30 @@ Global
 		{85FF85BD-F572-4F0A-A11E-FA855D480C1D}.Release|x64.Build.0 = Release|Any CPU
 		{85FF85BD-F572-4F0A-A11E-FA855D480C1D}.Release|x86.ActiveCfg = Release|Any CPU
 		{85FF85BD-F572-4F0A-A11E-FA855D480C1D}.Release|x86.Build.0 = Release|Any CPU
+		{C21FB23F-F131-4651-8236-4F3E076B40BF}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{C21FB23F-F131-4651-8236-4F3E076B40BF}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{C21FB23F-F131-4651-8236-4F3E076B40BF}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{C21FB23F-F131-4651-8236-4F3E076B40BF}.Debug|x64.Build.0 = Debug|Any CPU
+		{C21FB23F-F131-4651-8236-4F3E076B40BF}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{C21FB23F-F131-4651-8236-4F3E076B40BF}.Debug|x86.Build.0 = Debug|Any CPU
+		{C21FB23F-F131-4651-8236-4F3E076B40BF}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{C21FB23F-F131-4651-8236-4F3E076B40BF}.Release|Any CPU.Build.0 = Release|Any CPU
+		{C21FB23F-F131-4651-8236-4F3E076B40BF}.Release|x64.ActiveCfg = Release|Any CPU
+		{C21FB23F-F131-4651-8236-4F3E076B40BF}.Release|x64.Build.0 = Release|Any CPU
+		{C21FB23F-F131-4651-8236-4F3E076B40BF}.Release|x86.ActiveCfg = Release|Any CPU
+		{C21FB23F-F131-4651-8236-4F3E076B40BF}.Release|x86.Build.0 = Release|Any CPU
+		{C355307C-D7D3-48C7-9615-CB5FBCF83D49}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{C355307C-D7D3-48C7-9615-CB5FBCF83D49}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{C355307C-D7D3-48C7-9615-CB5FBCF83D49}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{C355307C-D7D3-48C7-9615-CB5FBCF83D49}.Debug|x64.Build.0 = Debug|Any CPU
+		{C355307C-D7D3-48C7-9615-CB5FBCF83D49}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{C355307C-D7D3-48C7-9615-CB5FBCF83D49}.Debug|x86.Build.0 = Debug|Any CPU
+		{C355307C-D7D3-48C7-9615-CB5FBCF83D49}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{C355307C-D7D3-48C7-9615-CB5FBCF83D49}.Release|Any CPU.Build.0 = Release|Any CPU
+		{C355307C-D7D3-48C7-9615-CB5FBCF83D49}.Release|x64.ActiveCfg = Release|Any CPU
+		{C355307C-D7D3-48C7-9615-CB5FBCF83D49}.Release|x64.Build.0 = Release|Any CPU
+		{C355307C-D7D3-48C7-9615-CB5FBCF83D49}.Release|x86.ActiveCfg = Release|Any CPU
+		{C355307C-D7D3-48C7-9615-CB5FBCF83D49}.Release|x86.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -232,6 +260,8 @@ Global
 		{E3A79C5F-FDD4-4DC8-9D3F-13962C6FC27E} = {0AB3BF05-4346-4AA6-1389-037BE0695223}
 		{734AC2F7-B243-4211-95CF-3E662D2E20C9} = {827E0CD3-B72D-47B6-A68D-7590B98EB39B}
 		{85FF85BD-F572-4F0A-A11E-FA855D480C1D} = {0AB3BF05-4346-4AA6-1389-037BE0695223}
+		{C21FB23F-F131-4651-8236-4F3E076B40BF} = {827E0CD3-B72D-47B6-A68D-7590B98EB39B}
+		{C355307C-D7D3-48C7-9615-CB5FBCF83D49} = {0AB3BF05-4346-4AA6-1389-037BE0695223}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {DD14EF4D-167E-4AC7-953A-AF606CC34829}
diff --git a/src/HSchool.Ai/DayPlan.cs b/src/HSchool.Ai/DayPlan.cs
new file mode 100644
index 0000000..35c6ce5
--- /dev/null
+++ b/src/HSchool.Ai/DayPlan.cs
@@ -0,0 +1,125 @@
+using HSchool.Content;
+using HSchool.People;
+using HSchool.Schedule;
+
+namespace HSchool.Ai;
+
+/// <summary>When this person appears at the yard and when they start walking home today.</summary>
+public readonly record struct DayPlan(DateOnly Day, DateTime? AppearAt, DateTime? WalkHomeAt, string? FirstRoom)
+{
+    public bool Comes => AppearAt is not null;
+}
+
+public static class DayPlans
+{
+    private const int ExtraRollMax = 7;
+
+    public static DayPlan Build(
+        DefCatalog catalog,
+        WalkGraph walks,
+        Person person,
+        SchoolClass? schoolClass,
+        Timetable? timetable,
+        DateTime time,
+        int weekDays,
+        int schoolSeed)
+    {
+        ArgumentNullException.ThrowIfNull(catalog);
+        ArgumentNullException.ThrowIfNull(walks);
+        ArgumentNullException.ThrowIfNull(person);
+
+        var utc = DateTime.SpecifyKind(time, DateTimeKind.Utc);
+        var day = DateOnly.FromDateTime(utc);
+        if (!Duty.ComesToday(person, timetable, catalog, utc, weekDays) || catalog.DayFrame is null)
+        {
+            return new DayPlan(day, null, null, null);
+        }
+
+        var weekday = SchoolDay.WeekdayIndex(utc);
+        var firstRoom = FirstRoom(person, schoolClass, timetable, catalog, weekday);
+        if (firstRoom is null)
+        {
+            return new DayPlan(day, null, null, null);
+        }
+
+        var firstStart = FirstStart(person, schoolClass, timetable, catalog, weekday);
+        var lastEnd = LastEnd(person, schoolClass, timetable, catalog, weekday);
+        var travel = walks.Minutes(walks.TerritoryId, firstRoom);
+        if (float.IsInfinity(travel))
+        {
+            travel = 0f;
+        }
+
+        var slack = SlackMinutes(catalog, person, schoolSeed, day);
+        var appear = DateTime.SpecifyKind(utc.Date.Add(firstStart.ToTimeSpan()).AddMinutes(-(travel + slack)), DateTimeKind.Utc);
+        var walkHome = DateTime.SpecifyKind(utc.Date.Add(lastEnd.ToTimeSpan()), DateTimeKind.Utc);
+        return new DayPlan(day, appear, walkHome, firstRoom);
+    }
+
+    private static string? FirstRoom(
+        Person person,
+        SchoolClass? schoolClass,
+        Timetable? timetable,
+        DefCatalog catalog,
+        int weekday)
+    {
+        if (Duty.IsOtherStaff(person))
+        {
+            return person.WorkplaceRoomId;
+        }
+
+        var lessons = Duty.LessonsToday(person, schoolClass, timetable, weekday);
+        return lessons.Count > 0 ? lessons[0].RoomId : schoolClass?.RoomId;
+    }
+
+    private static TimeOnly FirstStart(
+        Person person,
+        SchoolClass? schoolClass,
+        Timetable? timetable,
+        DefCatalog catalog,
+        int weekday)
+    {
+        var frame = catalog.DayFrame!;
+        if (Duty.IsOtherStaff(person))
+        {
+            return SchoolDay.PeriodStart(frame, 1);
+        }
+
+        var lessons = Duty.LessonsToday(person, schoolClass, timetable, weekday);
+        return lessons.Count > 0 ? SchoolDay.PeriodStart(frame, lessons[0].Period) : SchoolDay.PeriodStart(frame, 1);
+    }
+
+    private static TimeOnly LastEnd(
+        Person person,
+        SchoolClass? schoolClass,
+        Timetable? timetable,
+        DefCatalog catalog,
+        int weekday)
+    {
+        var frame = catalog.DayFrame!;
+        if (Duty.IsOtherStaff(person))
+        {
+            return SchoolDay.PeriodEnd(frame, frame.LessonCount);
+        }
+
+        var lessons = Duty.LessonsToday(person, schoolClass, timetable, weekday);
+        return lessons.Count > 0
+            ? SchoolDay.PeriodEnd(frame, lessons[^1].Period)
+            : SchoolDay.PeriodEnd(frame, frame.LessonCount);
+    }
+
+    private static int SlackMinutes(DefCatalog catalog, Person person, int schoolSeed, DateOnly day)
+    {
+        var rng = new Random(Seed.Mix(schoolSeed, person.Id, day.DayNumber, Seed.CommuteSalt));
+        var extra = rng.Next(0, ExtraRollMax);
+        foreach (var name in person.Traits)
+        {
+            if (catalog.Traits.TryGetValue(name, out var trait))
+            {
+                extra += trait.CommuteMinutes;
+            }
+        }
+
+        return extra;
+    }
+}
diff --git a/src/HSchool.Ai/Duty.cs b/src/HSchool.Ai/Duty.cs
new file mode 100644
index 0000000..1c64f62
--- /dev/null
+++ b/src/HSchool.Ai/Duty.cs
@@ -0,0 +1,157 @@
+using HSchool.Content;
+using HSchool.People;
+using HSchool.Schedule;
+
+namespace HSchool.Ai;
+
+/// <summary>
+/// Where this person ought to be right now. The timetable and the job, not the walk graph.
+/// </summary>
+public static class Duty
+{
+    /// <summary>
+    /// The room of the current obligation, or <see langword="null"/> when they should be off campus.
+    /// A hole in the class table sends the pupil to their homeroom.
+    /// </summary>
+    public static string? RoomAt(
+        Person person,
+        SchoolClass? schoolClass,
+        Timetable? timetable,
+        DefCatalog catalog,
+        DateTime time,
+        int weekDays)
+    {
+        ArgumentNullException.ThrowIfNull(person);
+        ArgumentNullException.ThrowIfNull(catalog);
+
+        if (!ComesToday(person, timetable, catalog, time, weekDays))
+        {
+            return null;
+        }
+
+        if (IsOtherStaff(person))
+        {
+            return person.WorkplaceRoomId;
+        }
+
+        var utc = DateTime.SpecifyKind(time, DateTimeKind.Utc);
+        if (!SchoolDay.IsWorkday(catalog, utc, weekDays))
+        {
+            return null;
+        }
+
+        var slot = SchoolDay.At(catalog, utc, weekDays);
+        var day = SchoolDay.WeekdayIndex(utc);
+        var lessons = LessonsToday(person, schoolClass, timetable, day);
+        if (lessons.Count == 0)
+        {
+            return person.WorkplaceRoomId;
+        }
+
+        if (slot.Kind == DaySlotKind.Lesson)
+        {
+            var current = lessons.FirstOrDefault(lesson => lesson.Period == slot.Index);
+            if (current is not null)
+            {
+                return current.RoomId;
+            }
+
+            return schoolClass?.RoomId ?? person.WorkplaceRoomId;
+        }
+
+        if (slot.Kind == DaySlotKind.Break)
+        {
+            var next = lessons.Where(lesson => lesson.Period > slot.Index).OrderBy(lesson => lesson.Period).FirstOrDefault();
+            return next?.RoomId ?? schoolClass?.RoomId ?? person.WorkplaceRoomId;
+        }
+
+        var frame = catalog.DayFrame;
+        if (frame is not null
+            && SchoolDay.TryParseTime(frame.FirstLesson, out var first)
+            && utc.TimeOfDay < first.ToTimeSpan())
+        {
+            return lessons[0].RoomId;
+        }
+
+        if (frame is not null
+            && SchoolDay.TryLastBell(catalog, out var last)
+            && utc.TimeOfDay >= last.ToTimeSpan())
+        {
+            return null;
+        }
+
+        return lessons[0].RoomId;
+    }
+
+    public static bool ComesToday(
+        Person person,
+        Timetable? timetable,
+        DefCatalog catalog,
+        DateTime time,
+        int weekDays)
+    {
+        if (person.IsParent && !person.IsStaff && !person.IsStudent)
+        {
+            return false;
+        }
+
+        if (!SchoolDay.IsWorkday(catalog, time, weekDays))
+        {
+            return false;
+        }
+
+        if (IsOtherStaff(person))
+        {
+            return true;
+        }
+
+        var day = SchoolDay.WeekdayIndex(time);
+        if (person.IsStudent)
+        {
+            return timetable?.Lessons.Any(lesson =>
+                lesson.ClassId == person.ClassId && lesson.Day == day) == true;
+        }
+
+        if (person.IsStaff)
+        {
+            return timetable?.Lessons.Any(lesson =>
+                lesson.TeacherId == person.Id && lesson.Day == day) == true;
+        }
+
+        return false;
+    }
+
+    public static bool IsOtherStaff(Person person) =>
+        person.IsStaff && !Staffing.TeacherPosition.Equals(person.Position, StringComparison.Ordinal);
+
+    public static IReadOnlyList<LessonPlacement> LessonsToday(
+        Person person,
+        SchoolClass? schoolClass,
+        Timetable? timetable,
+        int day)
+    {
+        if (timetable is null)
+        {
+            return [];
+        }
+
+        if (person.IsStudent)
+        {
+            var classId = person.ClassId ?? schoolClass?.Id;
+            return timetable.Lessons
+                .Where(lesson => lesson.ClassId == classId && lesson.Day == day)
+                .OrderBy(lesson => lesson.Period)
+                .ToArray();
+        }
+
+        if (person.IsStaff)
+        {
+            return timetable.Lessons
+                .Where(lesson => lesson.TeacherId == person.Id && lesson.Day == day)
+                .OrderBy(lesson => lesson.Period)
+                .ToArray();
+        }
+
+        return [];
+    }
+}
diff --git a/src/HSchool.Ai/HSchool.Ai.csproj b/src/HSchool.Ai/HSchool.Ai.csproj
new file mode 100644
index 0000000..7c60b96
--- /dev/null
+++ b/src/HSchool.Ai/HSchool.Ai.csproj
@@ -0,0 +1,17 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <RootNamespace>HSchool.Ai</RootNamespace>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\HSchool.Content\HSchool.Content.csproj" />
+    <ProjectReference Include="..\HSchool.People\HSchool.People.csproj" />
+    <ProjectReference Include="..\HSchool.Schedule\HSchool.Schedule.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <InternalsVisibleTo Include="HSchool.Ai.Tests" />
+  </ItemGroup>
+
+</Project>
diff --git a/src/HSchool.Ai/Presence.cs b/src/HSchool.Ai/Presence.cs
new file mode 100644
index 0000000..90fbd18
--- /dev/null
+++ b/src/HSchool.Ai/Presence.cs
@@ -0,0 +1,79 @@
+namespace HSchool.Ai;
+
+/// <summary>
+/// One person's place on the graph. <see cref="NodeId"/> is null when they are off campus.
+/// There is no "on an edge" state — remaining minutes are spent occupying the current node.
+/// </summary>
+public readonly record struct Presence(
+    string? NodeId,
+    float RemainingMinutes,
+    string? DestinationId,
+    bool HeadingHome,
+    string[] Path)
+{
+    public static Presence OffCampus { get; } = new(null, 0f, null, false, []);
+
+    public bool IsOnCampus => NodeId is not null;
+}
+
+/// <summary>
+/// Hot-path movement in the library so tests can prove travel time without a world. Simulation
+/// copies the same loop onto components and does not call this every tick.
+/// </summary>
+public static class PresenceStepper
+{
+    public static Presence Advance(Presence presence, WalkGraph walks, float minutes)
+    {
+        ArgumentNullException.ThrowIfNull(walks);
+        if (presence.NodeId is null || minutes <= 0)
+        {
+            return presence;
+        }
+
+        var remaining = presence.RemainingMinutes - minutes;
+        var node = presence.NodeId;
+        var path = presence.Path;
+        var index = 0;
+        while (remaining <= 0 && index < path.Length)
+        {
+            node = path[index];
+            index++;
+            remaining += walks.TravelMinutes(node);
+        }
+
+        if (remaining < 0)
+        {
+            remaining = 0;
+        }
+
+        var leftover = index >= path.Length ? [] : path[index..];
+        return presence with { NodeId = node, RemainingMinutes = remaining, Path = leftover };
+    }
+
+    public static Presence StartWalk(Presence presence, WalkGraph walks, string destination, bool headingHome)
+    {
+        ArgumentNullException.ThrowIfNull(walks);
+        if (presence.NodeId is null)
+        {
+            var path = walks.Path(walks.TerritoryId, destination);
+            return new Presence(walks.TerritoryId, 0f, destination, headingHome, [.. path]);
+        }
+
+        var hops = walks.Path(presence.NodeId, destination);
+        return presence with
+        {
+            DestinationId = destination,
+            HeadingHome = headingHome,
+            Path = [.. hops],
+        };
+    }
+
+    public static Presence ArriveOffCampus(Presence presence) =>
+        presence.NodeId is not null
+        && presence.HeadingHome
+        && presence.Path.Length == 0
+        && presence.RemainingMinutes <= 0
+        && presence.NodeId.Equals(presence.DestinationId, StringComparison.Ordinal)
+            ? Presence.OffCampus
+            : presence;
+}
diff --git a/src/HSchool.Ai/WalkGraph.cs b/src/HSchool.Ai/WalkGraph.cs
new file mode 100644
index 0000000..b641128
--- /dev/null
+++ b/src/HSchool.Ai/WalkGraph.cs
@@ -0,0 +1,165 @@
+using HSchool.Content;
+
+namespace HSchool.Ai;
+
+/// <summary>
+/// Next-hop matrix for a school's walkable graph. Built once when the school loads; querying a
+/// path does not search again.
+/// </summary>
+public sealed class WalkGraph
+{
+    private const float Unreachable = float.PositiveInfinity;
+
+    private readonly string[] _nodes;
+    private readonly Dictionary<string, int> _index;
+    private readonly float[] _travel;
+    private readonly float[,] _distance;
+    private readonly int[,] _next;
+
+    private WalkGraph(
+        string territoryId,
+        string[] nodes,
+        Dictionary<string, int> index,
+        float[] travel,
+        float[,] distance,
+        int[,] next)
+    {
+        TerritoryId = territoryId;
+        _nodes = nodes;
+        _index = index;
+        _travel = travel;
+        _distance = distance;
+        _next = next;
+    }
+
+    public string TerritoryId { get; }
+
+    public IReadOnlyList<string> Nodes => _nodes;
+
+    public static WalkGraph Build(DefCatalog catalog, MapLayout map)
+    {
+        ArgumentNullException.ThrowIfNull(catalog);
+        ArgumentNullException.ThrowIfNull(map);
+        if (map.Territory is null)
+        {
+            throw new ArgumentException("A walk graph needs a territory node.", nameof(map));
+        }
+
+        var nodes = new List<string> { map.Territory.Id };
+        foreach (var room in map.Rooms.OrderBy(room => room.Id, StringComparer.Ordinal))
+        {
+            nodes.Add(room.Id);
+        }
+
+        var count = nodes.Count;
+        var index = new Dictionary<string, int>(count, StringComparer.Ordinal);
+        var travel = new float[count];
+        for (var i = 0; i < count; i++)
+        {
+            var id = nodes[i];
+            index[id] = i;
+            travel[i] = TravelOf(catalog, map, id);
+        }
+
+        var distance = new float[count, count];
+        var next = new int[count, count];
+        for (var i = 0; i < count; i++)
+        {
+            for (var j = 0; j < count; j++)
+            {
+                distance[i, j] = i == j ? 0f : Unreachable;
+                next[i, j] = -1;
+            }
+        }
+
+        foreach (var link in map.Links)
+        {
+            if (!index.TryGetValue(link.A, out var a) || !index.TryGetValue(link.B, out var b))
+            {
+                continue;
+            }
+
+            distance[a, b] = travel[b];
+            next[a, b] = b;
+            distance[b, a] = travel[a];
+            next[b, a] = a;
+        }
+
+        for (var k = 0; k < count; k++)
+        {
+            for (var i = 0; i < count; i++)
+            {
+                for (var j = 0; j < count; j++)
+                {
+                    var via = distance[i, k] + distance[k, j];
+                    if (via < distance[i, j])
+                    {
+                        distance[i, j] = via;
+                        next[i, j] = next[i, k];
+                    }
+                }
+            }
+        }
+
+        return new WalkGraph(map.Territory.Id, [.. nodes], index, travel, distance, next);
+    }
+
+    public float TravelMinutes(string nodeId) =>
+        _index.TryGetValue(nodeId, out var i) ? _travel[i] : 0f;
+
+    /// <summary>Hops after <paramref name="from"/>, including <paramref name="to"/>. Empty when already there.</summary>
+    public IReadOnlyList<string> Path(string from, string to)
+    {
+        if (from.Equals(to, StringComparison.Ordinal))
+        {
+            return [];
+        }
+
+        if (!_index.TryGetValue(from, out var i) || !_index.TryGetValue(to, out var j) || _next[i, j] < 0)
+        {
+            return [];
+        }
+
+        var hops = new List<string>();
+        while (i != j)
+        {
+            i = _next[i, j];
+            if (i < 0)
+            {
+                return [];
+            }
+
+            hops.Add(_nodes[i]);
+        }
+
+        return hops;
+    }
+
+    public float Minutes(string from, string to)
+    {
+        if (!_index.TryGetValue(from, out var i) || !_index.TryGetValue(to, out var j))
+        {
+            return Unreachable;
+        }
+
+        return _distance[i, j];
+    }
+
+    private static float TravelOf(DefCatalog catalog, MapLayout map, string id)
+    {
+        if (map.Territory is not null && id.Equals(map.Territory.Id, StringComparison.Ordinal))
+        {
+            return catalog.Territories.TryGetValue(map.Territory.Def, out var territory)
+                ? territory.TravelMinutes
+                : 0f;
+        }
+
+        var room = map.Rooms.FirstOrDefault(candidate => candidate.Id.Equals(id, StringComparison.Ordinal));
+        if (room is not null && catalog.Rooms.TryGetValue(room.Def, out var def))
+        {
+            return def.TravelMinutes;
+        }
+
+        return 0f;
+    }
+}
diff --git a/src/HSchool.Content/CatalogLoader.cs b/src/HSchool.Content/CatalogLoader.cs
index eb2edb2..a97e0a0 100644
--- a/src/HSchool.Content/CatalogLoader.cs
+++ b/src/HSchool.Content/CatalogLoader.cs
@@ -468,6 +468,19 @@ public sealed class CatalogLoader
             {
                 throw new ContentLoadException($"RoomDef '{room.DefName}' is not a homeroom and cannot set seatThing or defaultSeats.");
             }
+
+            if (!room.Abstract && room.TravelMinutes <= 0)
+            {
+                throw new ContentLoadException($"RoomDef '{room.DefName}' travelMinutes must be positive.");
+            }
+        }
+
+        foreach (var territory in catalog.Territories.Values)
+        {
+            if (!territory.Abstract && territory.TravelMinutes <= 0)
+            {
+                throw new ContentLoadException($"TerritoryDef '{territory.DefName}' travelMinutes must be positive.");
+            }
         }
 
         PeopleDefValidator.Validate(catalog);
diff --git a/src/HSchool.Content/Defs.cs b/src/HSchool.Content/Defs.cs
index 1dcbbfc..155d488 100644
--- a/src/HSchool.Content/Defs.cs
+++ b/src/HSchool.Content/Defs.cs
@@ -77,10 +77,17 @@ public sealed class RoomDef : Def
 
     /// <summary>Editor default when placing a new homeroom. Vanilla classrooms are 16.</summary>
     public int DefaultSeats { get; init; }
+
+    /// <summary>Game minutes spent occupying this room when walking through it.</summary>
+    public float TravelMinutes { get; init; }
 }
 
 public sealed class BuildingDef : Def;
 
 public sealed class FloorDef : Def;
 
-public sealed class TerritoryDef : Def;
+public sealed class TerritoryDef : Def
+{
+    /// <summary>Game minutes spent occupying the yard when walking through it.</summary>
+    public float TravelMinutes { get; init; }
+}
diff --git a/src/HSchool.Content/PeopleDefs.cs b/src/HSchool.Content/PeopleDefs.cs
index 013abc1..aaf179c 100644
--- a/src/HSchool.Content/PeopleDefs.cs
+++ b/src/HSchool.Content/PeopleDefs.cs
@@ -167,6 +167,11 @@ public sealed class TraitDef : Def
     /// Added to the hourly wage ask. Positive means the person wants more at the same skills.
     /// </summary>
     public float WageAsk { get; init; }
+
+    /// <summary>
+    /// Extra minutes of commute slack. Positive arrives earlier; negative cuts it closer.
+    /// </summary>
+    public int CommuteMinutes { get; init; }
 }
 
 public sealed class StaffingDef : Def
diff --git a/src/HSchool.Content/SchoolDay.cs b/src/HSchool.Content/SchoolDay.cs
index 37924ad..9b4ee6b 100644
--- a/src/HSchool.Content/SchoolDay.cs
+++ b/src/HSchool.Content/SchoolDay.cs
@@ -95,6 +95,113 @@ public static class SchoolDay
         return stamp >= start || stamp <= end;
     }
 
+    /// <summary>The work window opens at six — the same hour a new school starts.</summary>
+    public static TimeOnly DayStart { get; } = new(6, 0);
+
+    public static bool IsWorkday(DefCatalog catalog, DateTime time, int weekDays)
+    {
+        ArgumentNullException.ThrowIfNull(catalog);
+        EnsureWeekDays(weekDays);
+        var utc = DateTime.SpecifyKind(time, DateTimeKind.Utc);
+        return IsWeekday(utc, weekDays) && !IsHoliday(catalog, utc);
+    }
+
+    /// <summary>
+    /// Six in the morning until the last bell of the day frame — not the actual timetable.
+    /// A school with no teachers still has a work window on a workday.
+    /// </summary>
+    public static bool InWorkWindow(DefCatalog catalog, DateTime time, int weekDays)
+    {
+        if (!IsWorkday(catalog, time, weekDays) || !TryLastBell(catalog, out var lastBell))
+        {
+            return false;
+        }
+
+        var clock = DateTime.SpecifyKind(time, DateTimeKind.Utc).TimeOfDay;
+        return clock >= DayStart.ToTimeSpan() && clock < lastBell.ToTimeSpan();
+    }
+
+    public static bool TryLastBell(DefCatalog catalog, out TimeOnly lastBell)
+    {
+        lastBell = default;
+        var frame = catalog.DayFrame;
+        if (frame is null || !TryParseTime(frame.FirstLesson, out _))
+        {
+            return false;
+        }
+
+        lastBell = PeriodEnd(frame, frame.LessonCount);
+        return true;
+    }
+
+    public static TimeOnly PeriodStart(DayFrameDef frame, int period)
+    {
+        ArgumentNullException.ThrowIfNull(frame);
+        if (period < 1 || period > frame.LessonCount)
+        {
+            throw new ArgumentOutOfRangeException(nameof(period), period, "Period is not on the day frame.");
+        }
+
+        if (!TryParseTime(frame.FirstLesson, out var first))
+        {
+            throw new ArgumentException($"Day frame firstLesson '{frame.FirstLesson}' is not a time.", nameof(frame));
+        }
+
+        var cursor = first.ToTimeSpan();
+        var lesson = TimeSpan.FromMinutes(frame.LessonMinutes);
+        for (var i = 1; i < period; i++)
+        {
+            cursor += lesson;
+            cursor += TimeSpan.FromMinutes(i == frame.LongBreakAfter ? frame.LongBreakMinutes : frame.BreakMinutes);
+        }
+
+        return TimeOnly.FromTimeSpan(cursor);
+    }
+
+    public static TimeOnly PeriodEnd(DayFrameDef frame, int period) =>
+        PeriodStart(frame, period).AddMinutes(frame.LessonMinutes);
+
+    /// <summary>
+    /// The next 6:00 of a workday that is still ahead. Night lands on the same morning;
+    /// evening, weekends and holidays walk forward. <see langword="null"/> when none exists
+    /// within <paramref name="maxDays"/>.
+    /// </summary>
+    public static DateTime? NextWorkMorning(DefCatalog catalog, DateTime time, int weekDays, int maxDays = 400)
+    {
+        ArgumentNullException.ThrowIfNull(catalog);
+        EnsureWeekDays(weekDays);
+        if (maxDays < 1)
+        {
+            throw new ArgumentOutOfRangeException(nameof(maxDays), maxDays, "Search must look at least one day ahead.");
+        }
+
+        var utc = DateTime.SpecifyKind(time, DateTimeKind.Utc);
+        var day = utc.Date;
+        if (utc.TimeOfDay < DayStart.ToTimeSpan() && IsWorkday(catalog, day, weekDays))
+        {
+            return DateTime.SpecifyKind(day.Add(DayStart.ToTimeSpan()), DateTimeKind.Utc);
+        }
+
+        for (var i = 1; i <= maxDays; i++)
+        {
+            var candidate = day.AddDays(i);
+            if (IsWorkday(catalog, candidate, weekDays))
+            {
+                return DateTime.SpecifyKind(candidate.Add(DayStart.ToTimeSpan()), DateTimeKind.Utc);
+            }
+        }
+
+        return null;
+    }
+
+    private static void EnsureWeekDays(int weekDays)
+    {
+        if (weekDays is < 5 or > 7)
+        {
+            throw new ArgumentOutOfRangeException(nameof(weekDays), weekDays, "School week must be 5–7 days.");
+        }
+    }
+
     private static bool IsWeekday(DateTime time, int weekDays)
     {
         // Monday = 0 … Sunday = 6. A 5-day week is Mon–Fri; 6 adds Saturday; 7 is every day.
diff --git a/src/HSchool.People/Seed.cs b/src/HSchool.People/Seed.cs
index 669e848..fe88def 100644
--- a/src/HSchool.People/Seed.cs
+++ b/src/HSchool.People/Seed.cs
@@ -4,7 +4,7 @@ namespace HSchool.People;
 /// Per-family streams derived from the school seed. Family N never consumes family N-1's rolls,
 /// so appending a thirteenth family leaves the first twelve unchanged.
 /// </summary>
-internal static class Seed
+public static class Seed
 {
     public const int ChildCountSalt = 1;
     public const int AppearanceSalt = 2;
@@ -12,6 +12,7 @@ internal static class Seed
     public const int SeatShuffleSalt = 4;
     public const int HouseholdSalt = 5;
     public const int ApplicantSalt = 6;
+    public const int CommuteSalt = 7;
 
     /// <summary>A stream that belongs to the school rather than to one family.</summary>
     public static int ForSchool(int schoolSeed, int salt) => Mix(schoolSeed, familyIndex: -1, salt);
@@ -24,6 +25,28 @@ internal static class Seed
         return (int)z;
     }
 
+    /// <summary>A stream that belongs to one person on one calendar day — commute slack, not looks.</summary>
+    public static int Mix(int schoolSeed, string personId, int dayNumber, int salt)
+    {
+        ArgumentNullException.ThrowIfNull(personId);
+        var z = Mix64((uint)schoolSeed);
+        z = Mix64(z ^ Stable(personId));
+        z = Mix64(z ^ (uint)(dayNumber + 1));
+        z = Mix64(z ^ (uint)(salt + 1));
+        return (int)z;
+    }
+
+    private static uint Stable(string value)
+    {
+        ulong z = 0;
+        foreach (var character in value)
+        {
+            z = Mix64(z ^ character);
+        }
+
+        return (uint)z;
+    }
+
     private static ulong Mix64(ulong z)
     {
         z += 0x9E3779B97F4A7C15UL;
diff --git a/src/HSchool.Server/Game/GameLoopService.cs b/src/HSchool.Server/Game/GameLoopService.cs
index f1dbb68..b66ebdb 100644
--- a/src/HSchool.Server/Game/GameLoopService.cs
+++ b/src/HSchool.Server/Game/GameLoopService.cs
@@ -494,7 +494,8 @@ internal sealed class GameLoopService(
                 isNew: false,
                 save.ModIds,
                 save.Map,
-                save.NameSetId);
+                save.NameSetId,
+                save.Presence);
             worker.Start();
 
             try
@@ -541,7 +542,8 @@ internal sealed class GameLoopService(
         bool isNew,
         IReadOnlyList<string>? modIds,
         MapLayout? map,
-        string? nameSetId) =>
+        string? nameSetId,
+        IReadOnlyList<PresenceSnapshot>? presence = null) =>
         new(
             id,
             name,
@@ -552,6 +554,7 @@ internal sealed class GameLoopService(
             modIds,
             map,
             nameSetId,
+            presence,
             _options,
             clients,
             metrics,
diff --git a/src/HSchool.Server/Game/SchoolStore.cs b/src/HSchool.Server/Game/SchoolStore.cs
index d789ba7..61c5618 100644
--- a/src/HSchool.Server/Game/SchoolStore.cs
+++ b/src/HSchool.Server/Game/SchoolStore.cs
@@ -27,6 +27,8 @@ internal sealed class SchoolSave
     public MapLayout? Map { get; init; }
 
     public string? NameSetId { get; init; }
+
+    public IReadOnlyList<PresenceSnapshot>? Presence { get; init; }
 }
 
 /// <summary>Allocates school ids that survive a process restart.</summary>
@@ -160,6 +162,7 @@ internal sealed class SchoolStore
                     ModIds = save.ModIds,
                     Map = save.Map,
                     NameSetId = save.NameSetId,
+                    Presence = save.Presence,
                 });
             }
             catch (Exception ex)
diff --git a/src/HSchool.Server/Game/SchoolWorker.cs b/src/HSchool.Server/Game/SchoolWorker.cs
index 00b472e..163d8b6 100644
--- a/src/HSchool.Server/Game/SchoolWorker.cs
+++ b/src/HSchool.Server/Game/SchoolWorker.cs
@@ -33,6 +33,7 @@ internal sealed class SchoolWorker
     private readonly IReadOnlyList<string>? _modIds;
     private readonly MapLayout? _savedMap;
     private readonly string? _nameSetId;
+    private readonly IReadOnlyList<PresenceSnapshot>? _savedPresence;
     private readonly Action<int> _onFailed;
 
     private readonly int _id;
@@ -64,6 +65,7 @@ internal sealed class SchoolWorker
         IReadOnlyList<string>? modIds,
         MapLayout? savedMap,
         string? nameSetId,
+        IReadOnlyList<PresenceSnapshot>? savedPresence,
         SimulationOptions options,
         ClientRegistry clients,
         GameMetrics metrics,
@@ -81,6 +83,7 @@ internal sealed class SchoolWorker
         _modIds = modIds;
         _savedMap = savedMap;
         _nameSetId = nameSetId;
+        _savedPresence = savedPresence;
         _options = options;
         _clients = clients;
         _metrics = metrics;
@@ -882,6 +885,8 @@ internal sealed class SchoolWorker
 
         school.InstallPeople(roster, seed, nameSetId, applicants);
         InstallTimetable(school);
+        school.ConfigurePresence(_options.SchoolWeekDays, _options.MaxDecisionsPerTick);
+        school.RestorePresence(_savedPresence);
         return generated;
     }
 
@@ -927,6 +932,7 @@ internal sealed class SchoolWorker
                 ModIds = school.Catalog?.PackIds,
                 Map = school.Map,
                 NameSetId = _nameSetId,
+                Presence = school.CapturePresence(),
             });
         }
         catch (Exception ex)
diff --git a/src/HSchool.Server/Program.cs b/src/HSchool.Server/Program.cs
index 7feaa46..b121b78 100644
--- a/src/HSchool.Server/Program.cs
+++ b/src/HSchool.Server/Program.cs
@@ -23,6 +23,7 @@ builder.Services
     .Validate(options => options.SaveIntervalSeconds is > 0 and <= 3600, "Simulation:SaveIntervalSeconds must be between 1 and 3600.")
     .Validate(options => options.MonthlyPayrollCap > 0, "Simulation:MonthlyPayrollCap must be positive.")
     .Validate(options => options.SchoolWeekDays is >= 5 and <= 7, "Simulation:SchoolWeekDays must be between 5 and 7.")
+    .Validate(options => options.MaxDecisionsPerTick is > 0 and <= 10_000, "Simulation:MaxDecisionsPerTick must be between 1 and 10000.")
     .ValidateOnStart();
 
 builder.Services.AddSingleton<GameCommandQueue>();
diff --git a/src/HSchool.Server/appsettings.json b/src/HSchool.Server/appsettings.json
index b483337..fed9c80 100644
--- a/src/HSchool.Server/appsettings.json
+++ b/src/HSchool.Server/appsettings.json
@@ -15,6 +15,7 @@
     "ModsDirectory": "mods",
     "SaveIntervalSeconds": 30,
     "MonthlyPayrollCap": 100000,
-    "SchoolWeekDays": 5
+    "SchoolWeekDays": 5,
+    "MaxDecisionsPerTick": 64
   }
 }
diff --git a/src/HSchool.Server/mods/core/defs/rooms/academic.jsonc b/src/HSchool.Server/mods/core/defs/rooms/academic.jsonc
index 48ea214..5a8ba01 100644
--- a/src/HSchool.Server/mods/core/defs/rooms/academic.jsonc
+++ b/src/HSchool.Server/mods/core/defs/rooms/academic.jsonc
@@ -5,6 +5,7 @@
     "seatThing": "StudentDesk",
     "defaultSeats": 16,
     "works": ["TeachLesson"],
+    "travelMinutes": 0.5,
   },
   {
     "defName": "Library",
@@ -14,6 +15,7 @@
     ],
     "positions": ["Librarian"],
     "works": ["LibraryWork"],
+    "travelMinutes": 0.5,
   },
   {
     "defName": "ComputerLab",
@@ -23,5 +25,6 @@
       { "key": "computers", "thing": "Computer", "count": 12 },
     ],
     "works": ["TeachLesson"],
+    "travelMinutes": 0.5,
   },
 ]
diff --git a/src/HSchool.Server/mods/core/defs/rooms/circulation.jsonc b/src/HSchool.Server/mods/core/defs/rooms/circulation.jsonc
index 2ba38c2..baf3faa 100644
--- a/src/HSchool.Server/mods/core/defs/rooms/circulation.jsonc
+++ b/src/HSchool.Server/mods/core/defs/rooms/circulation.jsonc
@@ -1,5 +1,5 @@
 [
   // Walkable rooms that exist to connect the graph: lobby, stairs. Empty on purpose.
-  { "defName": "EntranceHall" },
-  { "defName": "Stairwell" },
+  { "defName": "EntranceHall", "travelMinutes": 1 },
+  { "defName": "Stairwell", "travelMinutes": 1.5 },
 ]
diff --git a/src/HSchool.Server/mods/core/defs/rooms/corridor.jsonc b/src/HSchool.Server/mods/core/defs/rooms/corridor.jsonc
index f5a0b4b..d76892b 100644
--- a/src/HSchool.Server/mods/core/defs/rooms/corridor.jsonc
+++ b/src/HSchool.Server/mods/core/defs/rooms/corridor.jsonc
@@ -1,2 +1,2 @@
 // Empty on purpose: a corridor is a walkable room with no furniture of its own.
-{ "defName": "Corridor" }
+{ "defName": "Corridor", "travelMinutes": 1.5 }
diff --git a/src/HSchool.Server/mods/core/defs/rooms/gym-hall.jsonc b/src/HSchool.Server/mods/core/defs/rooms/gym-hall.jsonc
index 7ecafb8..568e817 100644
--- a/src/HSchool.Server/mods/core/defs/rooms/gym-hall.jsonc
+++ b/src/HSchool.Server/mods/core/defs/rooms/gym-hall.jsonc
@@ -4,4 +4,5 @@
     { "key": "benches", "thing": "Bench", "count": 4 },
   ],
   "works": ["PELesson"],
+  "travelMinutes": 0.5,
 }
diff --git a/src/HSchool.Server/mods/core/defs/rooms/principals-office.jsonc b/src/HSchool.Server/mods/core/defs/rooms/principals-office.jsonc
index 3482d93..c7ee218 100644
--- a/src/HSchool.Server/mods/core/defs/rooms/principals-office.jsonc
+++ b/src/HSchool.Server/mods/core/defs/rooms/principals-office.jsonc
@@ -7,4 +7,5 @@
   ],
   "positions": ["Principal"],
   "works": ["PrincipalOfficeWork", "TeachLesson", "WalkSchool"],
+  "travelMinutes": 0.5,
 }
diff --git a/src/HSchool.Server/mods/core/defs/rooms/service.jsonc b/src/HSchool.Server/mods/core/defs/rooms/service.jsonc
index 55e8feb..ed1990e 100644
--- a/src/HSchool.Server/mods/core/defs/rooms/service.jsonc
+++ b/src/HSchool.Server/mods/core/defs/rooms/service.jsonc
@@ -7,6 +7,7 @@
     ],
     "positions": ["Secretary"],
     "works": ["OfficeWork"],
+    "travelMinutes": 0.5,
   },
   {
     "defName": "TeachersRoom",
@@ -14,6 +15,7 @@
       { "key": "table", "thing": "DiningTable" },
       { "key": "chairs", "thing": "Chair", "count": 6 },
     ],
+    "travelMinutes": 0.5,
   },
   {
     "defName": "Cafeteria",
@@ -23,9 +25,11 @@
     ],
     "positions": ["CafeteriaCook"],
     "works": ["ServeLunch"],
+    "travelMinutes": 0.5,
   },
   {
     "defName": "Restroom",
+    "travelMinutes": 0.5,
   },
   {
     "defName": "MedicalOffice",
@@ -35,11 +39,13 @@
     ],
     "positions": ["Nurse"],
     "works": ["MedicalDuty"],
+    "travelMinutes": 0.5,
   },
   {
     "defName": "ChangingRoom",
     "slots": [
       { "key": "lockers", "thing": "Locker", "count": 12 },
     ],
+    "travelMinutes": 0.5,
   },
 ]
diff --git a/src/HSchool.Server/mods/core/defs/territories/school-yard.jsonc b/src/HSchool.Server/mods/core/defs/territories/school-yard.jsonc
index f2f6fa4..8e5002a 100644
--- a/src/HSchool.Server/mods/core/defs/territories/school-yard.jsonc
+++ b/src/HSchool.Server/mods/core/defs/territories/school-yard.jsonc
@@ -1 +1 @@
-{ "defName": "SchoolYard" }
+{ "defName": "SchoolYard", "travelMinutes": 3 }
diff --git a/src/HSchool.Server/mods/core/defs/traits/traits.jsonc b/src/HSchool.Server/mods/core/defs/traits/traits.jsonc
index 8fcc332..f737af4 100644
--- a/src/HSchool.Server/mods/core/defs/traits/traits.jsonc
+++ b/src/HSchool.Server/mods/core/defs/traits/traits.jsonc
@@ -2,6 +2,7 @@
   {
     "defName": "Diligent",
     "weight": 8,
+    "commuteMinutes": 4,
     "incompatible": ["Lazy", "AbsentMinded"],
     "skillModifiers": [
       { "skill": "Mathematics", "offset": 8 },
@@ -47,6 +48,7 @@
     "defName": "Lazy",
     "weight": 6,
     "incompatible": ["Diligent"],
+    "commuteMinutes": -4,
     "skillModifiers": [
       { "skill": "PhysicalEducation", "offset": -8 },
       { "skill": "Mathematics", "offset": -6 },
diff --git a/src/HSchool.Simulation/GameClock.cs b/src/HSchool.Simulation/GameClock.cs
index 68c17a6..72d0f64 100644
--- a/src/HSchool.Simulation/GameClock.cs
+++ b/src/HSchool.Simulation/GameClock.cs
@@ -50,6 +50,17 @@ public sealed class GameClock
 
     public static bool IsValidStartDate(DateTime date) => date >= MinStartDate && date <= MaxStartDate;
 
+    /// <summary>Empty-time skip. Not a tick — the calendar jumps to an instant already known to be legal.</summary>
+    public void JumpTo(DateTime time)
+    {
+        if (!IsValidStartDate(time))
+        {
+            throw new ArgumentOutOfRangeException(nameof(time), time, "Jump target is outside the supported range.");
+        }
+
+        Time = DateTime.SpecifyKind(time, DateTimeKind.Utc);
+    }
+
     /// <summary>
     /// Advances the calendar by one fixed step of <paramref name="realSeconds"/>, scaled by the
     /// base rate and the current speed. Does nothing while paused.
diff --git a/src/HSchool.Simulation/HSchool.Simulation.csproj b/src/HSchool.Simulation/HSchool.Simulation.csproj
index 7646613..6f95035 100644
--- a/src/HSchool.Simulation/HSchool.Simulation.csproj
+++ b/src/HSchool.Simulation/HSchool.Simulation.csproj
@@ -10,6 +10,7 @@
     </ItemGroup>
 
     <ItemGroup>
+      <ProjectReference Include="..\HSchool.Ai\HSchool.Ai.csproj" />
       <ProjectReference Include="..\HSchool.Content\HSchool.Content.csproj" />
       <ProjectReference Include="..\HSchool.People\HSchool.People.csproj" />
       <ProjectReference Include="..\HSchool.Schedule\HSchool.Schedule.csproj" />
diff --git a/src/HSchool.Simulation/PresenceSystem.cs b/src/HSchool.Simulation/PresenceSystem.cs
new file mode 100644
index 0000000..bf89d42
--- /dev/null
+++ b/src/HSchool.Simulation/PresenceSystem.cs
@@ -0,0 +1,374 @@
+using Arch.Core;
+using HSchool.Ai;
+using HSchool.Content;
+using HSchool.People;
+using HSchool.Schedule;
+
+namespace HSchool.Simulation;
+
+/// <summary>
+/// Decisions go through <see cref="HSchool.Ai"/>; the per-tick walk does not. Order is the
+/// roster id list, never Arch's entity order.
+/// </summary>
+internal static class PresenceSystem
+{
+    private static readonly QueryDescription People =
+        new QueryDescription().WithAll<PersonIdentity, PersonRoles, PersonTraits, Presence>();
+
+    public static void Apply(School school, double gameMinutes)
+    {
+        if (school.Catalog is null || school.Walks is null || school.Roster is null)
+        {
+            return;
+        }
+
+        EnsurePlans(school);
+        EnqueueEvents(school);
+        EnqueueTimeEvents(school, (float)gameMinutes);
+        DrainDecisions(school);
+        Move(school, (float)gameMinutes);
+        FinishHome(school);
+    }
+
+    public static bool IsEmpty(School school)
+    {
+        var empty = true;
+        var world = school.World;
+        world.Query(in People, (ref Presence presence) =>
+        {
+            if (presence.IsOnCampus)
+            {
+                empty = false;
+            }
+        });
+        return empty;
+    }
+
+    public static IReadOnlyList<PresenceSnapshot> Capture(School school)
+    {
+        var rows = new List<PresenceSnapshot>();
+        var world = school.World;
+        world.Query(in People, (ref PersonIdentity identity, ref Presence presence) =>
+        {
+            rows.Add(new PresenceSnapshot(
+                identity.Id,
+                presence.NodeId,
+                presence.RemainingMinutes,
+                presence.DestinationId,
+                presence.HeadingHome,
+                presence.Path));
+        });
+        rows.Sort((left, right) => StringComparer.Ordinal.Compare(left.PersonId, right.PersonId));
+        return rows;
+    }
+
+    public static void Restore(School school, IReadOnlyList<PresenceSnapshot>? saved)
+    {
+        // A new school has no snapshot: people stay off campus and walk in. Missing ids inside
+        // a real snapshot are hires and intake, and those land on their duty room.
+        if (saved is null)
+        {
+            return;
+        }
+
+        var byId = saved
+            .Where(row => !string.IsNullOrWhiteSpace(row.PersonId))
+            .ToDictionary(row => row.PersonId, StringComparer.Ordinal);
+        ForEachPerson(school, (person, _, ref presence) =>
+        {
+            if (!byId.TryGetValue(person.Id, out var row))
+            {
+                presence = PlaceByDuty(school, person);
+                return;
+            }
+
+            if (row.NodeId is null)
+            {
+                presence = Presence.OffCampus;
+                return;
+            }
+
+            presence = new Presence(
+                row.NodeId,
+                row.RemainingMinutes,
+                row.DestinationId,
+                row.HeadingHome,
+                row.Path?.ToArray() ?? []);
+        });
+    }
+
+    public static void PlaceMissingByDuty(School school)
+    {
+        ForEachPerson(school, (person, _, ref presence) =>
+        {
+            if (!presence.IsOnCampus)
+            {
+                presence = PlaceByDuty(school, person);
+            }
+        });
+    }
+
+    private static Presence PlaceByDuty(School school, Person person)
+    {
+        var room = Duty.RoomAt(
+            person,
+            ClassOf(school, person),
+            school.Timetable,
+            school.Catalog!,
+            school.Clock.Time,
+            school.SchoolWeekDays);
+        if (room is null || school.Walks is null)
+        {
+            return Presence.OffCampus;
+        }
+
+        return new Presence(room, 0f, room, false, []);
+    }
+
+    private static void EnsurePlans(School school)
+    {
+        var day = DateOnly.FromDateTime(school.Clock.Time);
+        if (school.PlanDay == day && school.Plans.Count == school.Roster!.People.Count)
+        {
+            return;
+        }
+
+        school.PlanDay = day;
+        school.Plans.Clear();
+        foreach (var person in school.Roster!.People)
+        {
+            school.Plans[person.Id] = DayPlans.Build(
+                school.Catalog!,
+                school.Walks!,
+                person,
+                ClassOf(school, person),
+                school.Timetable,
+                school.Clock.Time,
+                school.SchoolWeekDays,
+                school.PeopleSeed);
+        }
+
+        school.DecisionQueue.Clear();
+        foreach (var person in OrderedPeople(school))
+        {
+            school.DecisionQueue.Enqueue(person.Id);
+        }
+    }
+
+    private static void EnqueueEvents(School school)
+    {
+        var slot = SchoolDay.At(school.Catalog!, school.Clock.Time, school.SchoolWeekDays);
+        if (school.LastDecisionSlot == slot)
+        {
+            return;
+        }
+
+        school.LastDecisionSlot = slot;
+        foreach (var person in OrderedPeople(school))
+        {
+            school.DecisionQueue.Enqueue(person.Id);
+        }
+    }
+
+    private static void EnqueueTimeEvents(School school, float minutes)
+    {
+        if (minutes <= 0)
+        {
+            return;
+        }
+
+        var now = school.Clock.Time;
+        var previous = now.AddMinutes(-minutes);
+        foreach (var person in OrderedPeople(school))
+        {
+            if (!school.Plans.TryGetValue(person.Id, out var plan))
+            {
+                continue;
+            }
+
+            if (plan.AppearAt is { } appear && previous < appear && now >= appear)
+            {
+                school.DecisionQueue.Enqueue(person.Id);
+            }
+
+            if (plan.WalkHomeAt is { } leave && previous < leave && now >= leave)
+            {
+                school.DecisionQueue.Enqueue(person.Id);
+            }
+        }
+    }
+
+    private static void DrainDecisions(School school)
+    {
+        var budget = school.MaxDecisionsPerTick;
+        while (budget > 0 && school.DecisionQueue.Count > 0)
+        {
+            var id = school.DecisionQueue.Dequeue();
+            Decide(school, id);
+            budget--;
+        }
+    }
+
+    private static void Decide(School school, string personId)
+    {
+        var person = school.Roster!.People.FirstOrDefault(candidate => candidate.Id.Equals(personId, StringComparison.Ordinal));
+        if (person is null || !school.Plans.TryGetValue(personId, out var plan))
+        {
+            return;
+        }
+
+        var world = school.World;
+        var found = false;
+        world.Query(in People, (ref PersonIdentity identity, ref Presence presence) =>
+        {
+            if (found || !identity.Id.Equals(personId, StringComparison.Ordinal))
+            {
+                return;
+            }
+
+            found = true;
+            presence = NextPresence(school, person, plan, presence);
+        });
+    }
+
+    private static Presence NextPresence(School school, Person person, DayPlan plan, Presence presence)
+    {
+        var now = school.Clock.Time;
+        var walks = school.Walks!;
+        if (!presence.IsOnCampus)
+        {
+            if (plan.AppearAt is { } appear && now >= appear && (plan.WalkHomeAt is null || now < plan.WalkHomeAt))
+            {
+                var dest = plan.FirstRoom ?? Duty.RoomAt(
+                    person,
+                    ClassOf(school, person),
+                    school.Timetable,
+                    school.Catalog!,
+                    now,
+                    school.SchoolWeekDays);
+                return dest is null ? Presence.OffCampus : PresenceStepper.StartWalk(Presence.OffCampus, walks, dest, headingHome: false);
+            }
+
+            return Presence.OffCampus;
+        }
+
+        if (plan.WalkHomeAt is { } leave && now >= leave)
+        {
+            return PresenceStepper.StartWalk(presence, walks, walks.TerritoryId, headingHome: true);
+        }
+
+        var duty = Duty.RoomAt(
+            person,
+            ClassOf(school, person),
+            school.Timetable,
+            school.Catalog!,
+            now,
+            school.SchoolWeekDays);
+        if (duty is null)
+        {
+            return PresenceStepper.StartWalk(presence, walks, walks.TerritoryId, headingHome: true);
+        }
+
+        if (presence.HeadingHome || !duty.Equals(presence.DestinationId, StringComparison.Ordinal))
+        {
+            return PresenceStepper.StartWalk(presence, walks, duty, headingHome: false);
+        }
+
+        return presence;
+    }
+
+    private static void Move(School school, float minutes)
+    {
+        if (minutes <= 0 || school.Walks is null)
+        {
+            return;
+        }
+
+        var walks = school.Walks;
+        var world = school.World;
+        world.Query(in People, (ref Presence presence) =>
+        {
+            if (!presence.IsOnCampus)
+            {
+                return;
+            }
+
+            var remaining = presence.RemainingMinutes - minutes;
+            var node = presence.NodeId!;
+            var path = presence.Path;
+            var index = 0;
+            while (remaining <= 0 && index < path.Length)
+            {
+                node = path[index];
+                index++;
+                remaining += walks.TravelMinutes(node);
+            }
+
+            if (remaining < 0)
+            {
+                remaining = 0;
+            }
+
+            var leftover = index >= path.Length ? [] : path[index..];
+            presence = presence with { NodeId = node, RemainingMinutes = remaining, Path = leftover };
+        });
+    }
+
+    private static void FinishHome(School school)
+    {
+        var yard = school.Walks?.TerritoryId;
+        if (yard is null)
+        {
+            return;
+        }
+
+        var world = school.World;
+        world.Query(in People, (ref Presence presence) =>
+        {
+            if (presence.HeadingHome
+                && presence.NodeId is not null
+                && presence.Path.Length == 0
+                && presence.RemainingMinutes <= 0
+                && presence.NodeId.Equals(yard, StringComparison.Ordinal))
+            {
+                presence = Presence.OffCampus;
+            }
+        });
+    }
+
+    private static SchoolClass? ClassOf(School school, Person person)
+    {
+        if (person.ClassId is null)
+        {
+            return null;
+        }
+
+        return school.Roster?.Classes.FirstOrDefault(row => row.Id.Equals(person.ClassId, StringComparison.Ordinal));
+    }
+
+    private static IReadOnlyList<Person> OrderedPeople(School school) =>
+        school.Roster!.People.OrderBy(person => person.Id, StringComparer.Ordinal).ToArray();
+
+    private delegate void PersonAction(Person person, PersonIdentity identity, ref Presence presence);
+
+    private static void ForEachPerson(School school, PersonAction action)
+    {
+        var roster = school.Roster!.People.ToDictionary(person => person.Id, StringComparer.Ordinal);
+        var world = school.World;
+        world.Query(in People, (ref PersonIdentity identity, ref Presence presence) =>
+        {
+            if (roster.TryGetValue(identity.Id, out var person))
+            {
+                action(person, identity, ref presence);
+            }
+        });
+    }
+}
+
+public sealed record PresenceSnapshot(
+    string PersonId,
+    string? NodeId,
+    float RemainingMinutes,
+    string? DestinationId,
+    bool HeadingHome,
+    IReadOnlyList<string> Path);
diff --git a/src/HSchool.Simulation/RosterSpawner.cs b/src/HSchool.Simulation/RosterSpawner.cs
index 71dfbcd..5d7ff41 100644
--- a/src/HSchool.Simulation/RosterSpawner.cs
+++ b/src/HSchool.Simulation/RosterSpawner.cs
@@ -1,5 +1,6 @@
 using Arch.Core;
 using HSchool.People;
+using HSchool.Ai;
 
 namespace HSchool.Simulation;
 
@@ -36,7 +37,8 @@ public static class RosterSpawner
                     person.IsParent,
                     person.ClassId,
                     person.Position,
-                    person.WorkplaceRoomId));
+                    person.WorkplaceRoomId),
+                Presence.OffCampus);
         }
     }
 
diff --git a/src/HSchool.Simulation/School.cs b/src/HSchool.Simulation/School.cs
index f22fe82..627679c 100644
--- a/src/HSchool.Simulation/School.cs
+++ b/src/HSchool.Simulation/School.cs
@@ -1,4 +1,5 @@
 using Arch.Core;
+using HSchool.Ai;
 using HSchool.Content;
 using HSchool.People;
 using HSchool.Schedule;
@@ -83,6 +84,23 @@ public sealed class School : IDisposable
     /// <summary>True after yearly intake until the worker rebuilds around remaining locks.</summary>
     public bool TimetableDirty { get; private set; }
 
+    /// <summary>Walk matrix for this map. Null in clock-only tests.</summary>
+    internal WalkGraph? Walks { get; private set; }
+
+    internal int SchoolWeekDays { get; private set; } = 5;
+
+    internal int MaxDecisionsPerTick { get; private set; } = 64;
+
+    internal int MaxSkipDays { get; private set; } = 400;
+
+    internal DateOnly? PlanDay { get; set; }
+
+    internal DaySlot? LastDecisionSlot { get; set; }
+
+    internal Dictionary<string, DayPlan> Plans { get; } = new(StringComparer.Ordinal);
+
+    internal Queue<string> DecisionQueue { get; } = new();
+
     /// <summary>
     /// Installs a roster that already matches the map. Spawns entities; does not write to disk.
     /// </summary>
@@ -96,6 +114,61 @@ public sealed class School : IDisposable
         NameSetId = nameSetId;
         Applicants = applicants;
         RosterSpawner.Spawn(World, roster);
+        PlanDay = null;
+        LastDecisionSlot = null;
+        Plans.Clear();
+        DecisionQueue.Clear();
+    }
+
+    public void ConfigurePresence(int weekDays = 5, int maxDecisionsPerTick = 64, int maxSkipDays = 400)
+    {
+        ObjectDisposedException.ThrowIf(_disposed, this);
+        SchoolWeekDays = weekDays;
+        MaxDecisionsPerTick = maxDecisionsPerTick;
+        MaxSkipDays = maxSkipDays;
+        if (Catalog is not null && Map is not null)
+        {
+            Walks = WalkGraph.Build(Catalog, Map);
+        }
+    }
+
+    public IReadOnlyList<PresenceSnapshot> CapturePresence() => PresenceSystem.Capture(this);
+
+    public void RestorePresence(IReadOnlyList<PresenceSnapshot>? saved) => PresenceSystem.Restore(this, saved);
+
+    public bool IsCampusEmpty() => PresenceSystem.IsEmpty(this);
+
+    public SkipEmptyResult TrySkipEmpty()
+    {
+        ObjectDisposedException.ThrowIf(_disposed, this);
+        if (Catalog is null)
+        {
+            return SkipEmptyResult.Fail(SkipEmptyError.NoMorning);
+        }
+
+        if (!IsCampusEmpty())
+        {
+            return SkipEmptyResult.Fail(SkipEmptyError.PeoplePresent);
+        }
+
+        if (SchoolDay.InWorkWindow(Catalog, Clock.Time, SchoolWeekDays))
+        {
+            return SkipEmptyResult.Fail(SkipEmptyError.InWorkWindow);
+        }
+
+        var next = SchoolDay.NextWorkMorning(Catalog, Clock.Time, SchoolWeekDays, MaxSkipDays);
+        if (next is null)
+        {
+            return SkipEmptyResult.Fail(SkipEmptyError.NoMorning);
+        }
+
+        var before = Clock.Time;
+        Clock.JumpTo(next.Value);
+        var peopleChanged = TryYearlyIntake(before, next.Value);
+        peopleChanged |= TryApplicantRefresh();
+        PlanDay = null;
+        LastDecisionSlot = null;
+        return new SkipEmptyResult(SkipEmptyError.None, next.Value, peopleChanged);
     }
 
     /// <summary>
@@ -110,7 +183,9 @@ public sealed class School : IDisposable
 
         Roster = roster;
         Applicants = applicants;
+        var snapshot = PresenceSystem.Capture(this);
         RosterSpawner.Replace(World, roster);
+        PresenceSystem.Restore(this, snapshot);
         TimetableDirty = true;
     }
 
@@ -120,6 +195,11 @@ public sealed class School : IDisposable
         ArgumentNullException.ThrowIfNull(timetable);
         Timetable = timetable;
         TimetableDirty = false;
+        LastDecisionSlot = null;
+        foreach (var id in Roster?.People.Select(person => person.Id) ?? [])
+        {
+            DecisionQueue.Enqueue(id);
+        }
     }
 
     /// <summary>Runs one fixed step of the school: calendar, yearly intake, applicant refresh, then need decay.</summary>
@@ -135,6 +215,13 @@ public sealed class School : IDisposable
         {
             peopleChanged = TryYearlyIntake(before, Clock.Time);
             peopleChanged |= TryApplicantRefresh();
+            if (peopleChanged)
+            {
+                PlanDay = null;
+                LastDecisionSlot = null;
+            }
+
+            PresenceSystem.Apply(this, gameMinutes);
             if (Catalog is not null)
             {
                 NeedDecay.Apply(World, Catalog, gameMinutes);
@@ -160,7 +247,9 @@ public sealed class School : IDisposable
 
         if (changed)
         {
+            var snapshot = PresenceSystem.Capture(this);
             RosterSpawner.Replace(World, Roster);
+            PresenceSystem.Restore(this, snapshot);
             TimetableDirty = true;
         }
 
@@ -197,3 +286,18 @@ public sealed class School : IDisposable
         Arch.Core.World.Destroy(World);
     }
 }
+
+public enum SkipEmptyError
+{
+    None,
+    PeoplePresent,
+    InWorkWindow,
+    NoMorning,
+}
+
+public readonly record struct SkipEmptyResult(SkipEmptyError Error, DateTime? Time, bool PeopleChanged)
+{
+    public bool Succeeded => Error == SkipEmptyError.None;
+
+    public static SkipEmptyResult Fail(SkipEmptyError error) => new(error, null, false);
+}
diff --git a/src/HSchool.Simulation/SimulationOptions.cs b/src/HSchool.Simulation/SimulationOptions.cs
index e9a8ac3..6ebb783 100644
--- a/src/HSchool.Simulation/SimulationOptions.cs
+++ b/src/HSchool.Simulation/SimulationOptions.cs
@@ -55,6 +55,12 @@ public sealed class SimulationOptions
     /// </summary>
     public float MonthlyPayrollCap { get; set; } = 100_000f;
 
+    /// <summary>
+    /// How many people may change destination in one tick. Overflow waits for the next tick
+    /// instead of being dropped — a queue, not a cutoff.
+    /// </summary>
+    public int MaxDecisionsPerTick { get; set; } = 64;
+
     /// <summary>
     /// Working days from Monday. Five is Mon–Fri; six adds Saturday; seven is every day.
     /// </summary>
diff --git a/tests/HSchool.Ai.Tests/Fixtures.cs b/tests/HSchool.Ai.Tests/Fixtures.cs
new file mode 100644
index 0000000..71da36d
--- /dev/null
+++ b/tests/HSchool.Ai.Tests/Fixtures.cs
@@ -0,0 +1,53 @@
+using HSchool.Content;
+
+namespace HSchool.Ai.Tests;
+
+internal static class PackDocuments
+{
+    public static IReadOnlyList<ContentDocument> FromDirectory(string packId, string packRoot)
+    {
+        var documents = new List<ContentDocument>();
+        foreach (var path in Directory.EnumerateFiles(packRoot, "*.*", SearchOption.AllDirectories))
+        {
+            if (!path.EndsWith(".jsonc", StringComparison.OrdinalIgnoreCase)
+                && !path.EndsWith(".json", StringComparison.OrdinalIgnoreCase))
+            {
+                continue;
+            }
+
+            var relative = Path.GetRelativePath(packRoot, path).Replace('\\', '/');
+            documents.Add(new ContentDocument(packId, relative, File.ReadAllText(path)));
+        }
+
+        return documents;
+    }
+}
+
+internal static class Fixtures
+{
+    public static (DefCatalog Catalog, MapLayout Map) Vanilla()
+    {
+        var root = Path.Combine(AppContext.BaseDirectory, "vanilla");
+        var documents = PackDocuments.FromDirectory(CatalogLoader.CorePackId, root);
+        var catalog = new CatalogLoader().Load([CatalogLoader.CorePackId], documents);
+        var map = CatalogLoader.LastDefaultMap([CatalogLoader.CorePackId], documents);
+        Assert.NotNull(map);
+        return (catalog, map);
+    }
+
+    public static string RepoRoot()
+    {
+        var dir = new DirectoryInfo(AppContext.BaseDirectory);
+        while (dir is not null && !File.Exists(Path.Combine(dir.FullName, "h-school.sln")))
+        {
+            dir = dir.Parent;
+        }
+
+        if (dir is null)
+        {
+            throw new InvalidOperationException("Could not find h-school.sln from the test output directory.");
+        }
+
+        return dir.FullName;
+    }
+}
diff --git a/tests/HSchool.Ai.Tests/HSchool.Ai.Tests.csproj b/tests/HSchool.Ai.Tests/HSchool.Ai.Tests.csproj
new file mode 100644
index 0000000..d8bef11
--- /dev/null
+++ b/tests/HSchool.Ai.Tests/HSchool.Ai.Tests.csproj
@@ -0,0 +1,33 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <RootNamespace>HSchool.Ai.Tests</RootNamespace>
+    <IsTestProject>true</IsTestProject>
+    <OutputType>Exe</OutputType>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" />
+    <PackageReference Include="xunit.v3" />
+    <PackageReference Include="xunit.runner.visualstudio" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\src\HSchool.Ai\HSchool.Ai.csproj" />
+    <ProjectReference Include="..\..\src\HSchool.Content\HSchool.Content.csproj" />
+    <ProjectReference Include="..\..\src\HSchool.People\HSchool.People.csproj" />
+    <ProjectReference Include="..\..\src\HSchool.Schedule\HSchool.Schedule.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Using Include="Xunit" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Content Include="..\..\src\HSchool.Server\mods\core\**\*">
+      <Link>vanilla\%(RecursiveDir)%(Filename)%(Extension)</Link>
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
+  </ItemGroup>
+
+</Project>
diff --git a/tests/HSchool.Ai.Tests/WalkingTests.cs b/tests/HSchool.Ai.Tests/WalkingTests.cs
new file mode 100644
index 0000000..198420e
--- /dev/null
+++ b/tests/HSchool.Ai.Tests/WalkingTests.cs
@@ -0,0 +1,156 @@
+using HSchool.Content;
+using HSchool.People;
+using HSchool.Schedule;
+
+namespace HSchool.Ai.Tests;
+
+public class WalkingTests
+{
+    private static readonly DateTime TuesdayLesson = new(2012, 4, 3, 8, 45, 0, DateTimeKind.Utc);
+    private static readonly DateTime Sunday = new(2012, 4, 8, 10, 0, 0, DateTimeKind.Utc);
+    private static readonly DateTime SpringBreak = new(2012, 3, 31, 10, 0, 0, DateTimeKind.Utc);
+
+    [Fact]
+    public void PathFrom201ToFirstFloorRestroom_GoesThroughStairsAndCorridors()
+    {
+        var (catalog, map) = Fixtures.Vanilla();
+        var walks = WalkGraph.Build(catalog, map);
+
+        var hops = walks.Path("classroom-201", "restroom-1");
+
+        Assert.Equal(["corridor-2", "stairs-2", "stairs-1", "corridor-1", "restroom-1"], hops);
+        Assert.DoesNotContain("yard", hops);
+        Assert.Equal(6.5f, walks.Minutes("classroom-201", "restroom-1"));
+    }
+
+    [Fact]
+    public void PresenceStepper_TakesTheSameMinutesAsTheGraph()
+    {
+        var (catalog, map) = Fixtures.Vanilla();
+        var walks = WalkGraph.Build(catalog, map);
+        var hops = walks.Path("classroom-201", "restroom-1");
+        var cost = walks.Minutes("classroom-201", "restroom-1");
+        var presence = new Presence("classroom-201", 0f, "restroom-1", HeadingHome: false, [.. hops]);
+
+        var walked = PresenceStepper.Advance(presence, walks, cost);
+
+        Assert.Equal("restroom-1", walked.NodeId);
+        Assert.Empty(walked.Path);
+        Assert.Equal(0f, walked.RemainingMinutes);
+
+        var stepwise = presence;
+        var elapsed = 0f;
+        const float step = 0.25f;
+        while (stepwise.NodeId != "restroom-1" || stepwise.Path.Length > 0 || stepwise.RemainingMinutes > 0)
+        {
+            stepwise = PresenceStepper.Advance(stepwise, walks, step);
+            elapsed += step;
+            Assert.True(elapsed <= cost + step);
+        }
+
+        Assert.Equal(cost, elapsed);
+    }
+
+    [Fact]
+    public void GymAfterClassroom101_CostsSixMinutesAgainstATenMinuteBreak()
+    {
+        var (catalog, map) = Fixtures.Vanilla();
+        var walks = WalkGraph.Build(catalog, map);
+        var hops = walks.Path("classroom-101", "gym-hall");
+
+        Assert.Equal(["corridor-1", "porch", "yard", "gym-hall"], hops);
+        Assert.Equal(6f, walks.Minutes("classroom-101", "gym-hall"));
+        Assert.Equal(10, catalog.DayFrame!.BreakMinutes);
+        Assert.True(walks.Minutes("classroom-101", "gym-hall") < catalog.DayFrame.BreakMinutes);
+    }
+
+    [Fact]
+    public void ComesToday_IsFalseOnSundayAndHolidays()
+    {
+        var (catalog, map) = Fixtures.Vanilla();
+        var roster = RosterGenerator.Generate(catalog, map, schoolSeed: 1, "Slavic", TuesdayLesson);
+        var pupil = roster.People.First(person => person.IsStudent);
+        var schoolClass = roster.Classes.First(row => row.Id == pupil.ClassId);
+        var table = new Timetable(
+            [new LessonPlacement(schoolClass.Id, "Mathematics", "t1", schoolClass.RoomId, Day: 1, Period: 1)],
+            []);
+
+        Assert.True(Duty.ComesToday(pupil, table, catalog, TuesdayLesson, weekDays: 5));
+        Assert.False(Duty.ComesToday(pupil, table, catalog, Sunday, weekDays: 5));
+        Assert.False(Duty.ComesToday(pupil, table, catalog, SpringBreak, weekDays: 5));
+        Assert.False(Duty.ComesToday(
+            roster.People.First(person => person.IsParent && !person.IsStaff && !person.IsStudent),
+            table,
+            catalog,
+            TuesdayLesson,
+            weekDays: 5));
+    }
+
+    [Fact]
+    public void ClassWithoutLessons_StaysAway_TeacherWithAnotherClassComes()
+    {
+        var (catalog, map) = Fixtures.Vanilla();
+        var roster = RosterGenerator.Generate(catalog, map, schoolSeed: 1, "Slavic", TuesdayLesson);
+        var idle = roster.Classes[0];
+        var busy = roster.Classes[1];
+        var idlePupil = roster.People.First(person => person.Id == idle.PupilIds[0]);
+        var busyPupil = roster.People.First(person => person.Id == busy.PupilIds[0]);
+        var teacher = roster.People.First(person => person.IsParent && !person.IsStudent && !person.IsStaff) with
+        {
+            IsStaff = true,
+            Position = Staffing.TeacherPosition,
+        };
+        var table = new Timetable(
+            [new LessonPlacement(busy.Id, "Mathematics", teacher.Id, busy.RoomId, Day: 1, Period: 1)],
+            []);
+
+        Assert.False(Duty.ComesToday(idlePupil, table, catalog, TuesdayLesson, weekDays: 5));
+        Assert.True(Duty.ComesToday(busyPupil, table, catalog, TuesdayLesson, weekDays: 5));
+        Assert.True(Duty.ComesToday(teacher, table, catalog, TuesdayLesson, weekDays: 5));
+        Assert.Null(Duty.RoomAt(idlePupil, idle, table, catalog, TuesdayLesson, weekDays: 5));
+        Assert.Equal(busy.RoomId, Duty.RoomAt(busyPupil, busy, table, catalog, TuesdayLesson, weekDays: 5));
+        Assert.Equal(busy.RoomId, Duty.RoomAt(teacher, null, table, catalog, TuesdayLesson, weekDays: 5));
+    }
+
+    [Fact]
+    public void SameSeedAndMap_YieldTheSameDayPlan()
+    {
+        var (catalog, map) = Fixtures.Vanilla();
+        var walks = WalkGraph.Build(catalog, map);
+        var roster = RosterGenerator.Generate(catalog, map, schoolSeed: 9, "Slavic", TuesdayLesson);
+        var pupil = roster.People.First(person => person.IsStudent);
+        var schoolClass = roster.Classes.First(row => row.Id == pupil.ClassId);
+        var table = new Timetable(
+            [new LessonPlacement(schoolClass.Id, "Mathematics", "t1", schoolClass.RoomId, Day: 1, Period: 1)],
+            []);
+
+        var first = DayPlans.Build(catalog, walks, pupil, schoolClass, table, TuesdayLesson, weekDays: 5, schoolSeed: 9);
+        var second = DayPlans.Build(catalog, walks, pupil, schoolClass, table, TuesdayLesson, weekDays: 5, schoolSeed: 9);
+
+        Assert.Equal(first, second);
+        Assert.True(first.Comes);
+        Assert.Equal(schoolClass.RoomId, first.FirstRoom);
+        Assert.True(first.AppearAt < DateTime.SpecifyKind(TuesdayLesson.Date.Add(new TimeSpan(8, 30, 0)), DateTimeKind.Utc));
+    }
+
+    [Fact]
+    public void Assembly_DoesNotReferenceArchAspNetOrSockets()
+    {
+        var names = typeof(WalkGraph).Assembly.GetReferencedAssemblies().Select(assembly => assembly.Name!);
+        Assert.DoesNotContain(names, name => name.StartsWith("Arch", StringComparison.OrdinalIgnoreCase));
+        Assert.DoesNotContain(names, name => name.Contains("AspNet", StringComparison.OrdinalIgnoreCase));
+        Assert.DoesNotContain(names, name => name.Contains("Sockets", StringComparison.OrdinalIgnoreCase));
+    }
+
+    [Fact]
+    public void Sources_DoNotUseWallClock()
+    {
+        var root = Path.Combine(Fixtures.RepoRoot(), "src", "HSchool.Ai");
+        foreach (var path in Directory.EnumerateFiles(root, "*.cs"))
+        {
+            var text = File.ReadAllText(path);
+            Assert.DoesNotContain("DateTime.Now", text, StringComparison.Ordinal);
+            Assert.DoesNotContain("DateTime.UtcNow", text, StringComparison.Ordinal);
+        }
+    }
+}
diff --git a/tests/HSchool.Content.Tests/CalendarTests.cs b/tests/HSchool.Content.Tests/CalendarTests.cs
index 6e376e4..cd6167a 100644
--- a/tests/HSchool.Content.Tests/CalendarTests.cs
+++ b/tests/HSchool.Content.Tests/CalendarTests.cs
@@ -86,6 +86,52 @@ public class CalendarTests
         Assert.Equal(DaySlot.BreakAfter(2), slot);
     }
 
+    [Fact]
+    public void NextWorkMorning_FromSaturdayLandsOnMondaySix()
+    {
+        var catalog = LoadVanilla();
+        var next = SchoolDay.NextWorkMorning(catalog, new DateTime(2012, 4, 7, 10, 0, 0, DateTimeKind.Utc), weekDays: 5);
+
+        Assert.Equal(new DateTime(2012, 4, 9, 6, 0, 0, DateTimeKind.Utc), next);
+    }
+
+    [Fact]
+    public void NextWorkMorning_FromTuesdayNightLandsOnThatMorning()
+    {
+        var catalog = LoadVanilla();
+        var next = SchoolDay.NextWorkMorning(catalog, new DateTime(2012, 4, 3, 3, 0, 0, DateTimeKind.Utc), weekDays: 5);
+
+        Assert.Equal(new DateTime(2012, 4, 3, 6, 0, 0, DateTimeKind.Utc), next);
+    }
+
+    [Fact]
+    public void NextWorkMorning_FromTuesdayEveningLandsOnWednesday()
+    {
+        var catalog = LoadVanilla();
+        var next = SchoolDay.NextWorkMorning(catalog, new DateTime(2012, 4, 3, 22, 0, 0, DateTimeKind.Utc), weekDays: 5);
+
+        Assert.Equal(new DateTime(2012, 4, 4, 6, 0, 0, DateTimeKind.Utc), next);
+    }
+
+    [Fact]
+    public void InWorkWindow_SevenOnAWorkday_IsAlreadyOpen()
+    {
+        var catalog = LoadVanilla();
+        var seven = new DateTime(2012, 4, 3, 7, 0, 0, DateTimeKind.Utc);
+
+        Assert.True(SchoolDay.IsWorkday(catalog, seven, weekDays: 5));
+        Assert.True(SchoolDay.InWorkWindow(catalog, seven, weekDays: 5));
+    }
+
+    [Fact]
+    public void InWorkWindow_DoesNotNeedTeachers()
+    {
+        var catalog = LoadVanilla();
+        var morning = new DateTime(2012, 4, 3, 10, 0, 0, DateTimeKind.Utc);
+
+        Assert.True(SchoolDay.InWorkWindow(catalog, morning, weekDays: 5));
+    }
+
     [Fact]
     public void Subject_UnknownRoom_FailsTheCatalog()
     {
diff --git a/tests/HSchool.Content.Tests/CatalogLoaderTests.cs b/tests/HSchool.Content.Tests/CatalogLoaderTests.cs
index 5402c1b..2d6c650 100644
--- a/tests/HSchool.Content.Tests/CatalogLoaderTests.cs
+++ b/tests/HSchool.Content.Tests/CatalogLoaderTests.cs
@@ -106,7 +106,7 @@ public class CatalogLoaderTests
                     CatalogLoader.CorePackId,
                     "rooms",
                     "office",
-                    """{ "defName": "Office", "slots": [{ "key": "chair", "thing": "Chair" }], "positions": ["Principal"] }"""),
+                    """{ "defName": "Office", "slots": [{ "key": "chair", "thing": "Chair" }], "positions": ["Principal"], "travelMinutes": 1 }"""),
             ]));
 
         Assert.Contains("Chair", ex.Message);
@@ -126,4 +126,28 @@ public class CatalogLoaderTests
         Assert.Equal("Мебель", catalog.Label("ru", catalog.Things["Chair"]));
         Assert.Equal("Chair", catalog.Label("en", catalog.Things["Chair"]));
     }
+
+    [Fact]
+    public void ConcreteRoomWithoutTravelMinutes_FailsTheCatalog()
+    {
+        var ex = Assert.Throws<ContentLoadException>(() => _loader.Load(
+            [CatalogLoader.CorePackId],
+            [
+                PackDocuments.Def(CatalogLoader.CorePackId, "rooms", "office", """{ "defName": "Office" }"""),
+            ]));
+
+        Assert.Contains("travelMinutes", ex.Message, StringComparison.OrdinalIgnoreCase);
+    }
+
+    [Fact]
+    public void ConcreteTerritoryWithoutTravelMinutes_FailsTheCatalog()
+    {
+        var ex = Assert.Throws<ContentLoadException>(() => _loader.Load(
+            [CatalogLoader.CorePackId],
+            [
+                PackDocuments.Def(CatalogLoader.CorePackId, "territories", "yard", """{ "defName": "Yard" }"""),
+            ]));
+
+        Assert.Contains("travelMinutes", ex.Message, StringComparison.OrdinalIgnoreCase);
+    }
 }
diff --git a/tests/HSchool.Content.Tests/InheritanceTests.cs b/tests/HSchool.Content.Tests/InheritanceTests.cs
index 89b7133..69d6d7c 100644
--- a/tests/HSchool.Content.Tests/InheritanceTests.cs
+++ b/tests/HSchool.Content.Tests/InheritanceTests.cs
@@ -48,7 +48,7 @@ public class InheritanceTests
         var ex = Assert.Throws<ContentLoadException>(() => _loader.Load(
             [CatalogLoader.CorePackId],
             [
-                PackDocuments.Def(CatalogLoader.CorePackId, "rooms", "office", """{ "defName": "Office" }"""),
+                PackDocuments.Def(CatalogLoader.CorePackId, "rooms", "office", """{ "defName": "Office", "travelMinutes": 1 }"""),
                 PackDocuments.Def(CatalogLoader.CorePackId, "things", "chair", """{ "defName": "Chair", "parent": "Office" }"""),
             ]));
 
diff --git a/tests/HSchool.Content.Tests/MapValidationTests.cs b/tests/HSchool.Content.Tests/MapValidationTests.cs
index 726c202..12474ec 100644
--- a/tests/HSchool.Content.Tests/MapValidationTests.cs
+++ b/tests/HSchool.Content.Tests/MapValidationTests.cs
@@ -125,14 +125,14 @@ public class MapValidationTests
             CatalogLoader.CorePackId,
             "territories",
             "yard",
-            abstractYard ? """{ "defName": "Yard", "abstract": true }""" : """{ "defName": "Yard" }"""),
+            abstractYard ? """{ "defName": "Yard", "abstract": true }""" : """{ "defName": "Yard", "travelMinutes": 1 }"""),
         PackDocuments.Def(CatalogLoader.CorePackId, "buildings", "main", """{ "defName": "Main" }"""),
         PackDocuments.Def(CatalogLoader.CorePackId, "floors", "floor", """{ "defName": "Floor" }"""),
         PackDocuments.Def(
             CatalogLoader.CorePackId,
             "rooms",
             "office",
-            """{ "defName": "Office", "slots": [{ "key": "seat", "thing": "Chair" }], "positions": ["Principal"] }"""),
+            """{ "defName": "Office", "slots": [{ "key": "seat", "thing": "Chair" }], "positions": ["Principal"], "travelMinutes": 1 }"""),
     ];
 
     private static MapLayout MiniMap(
diff --git a/tests/HSchool.Content.Tests/MapViewTests.cs b/tests/HSchool.Content.Tests/MapViewTests.cs
index abc73b8..04b2127 100644
--- a/tests/HSchool.Content.Tests/MapViewTests.cs
+++ b/tests/HSchool.Content.Tests/MapViewTests.cs
@@ -62,7 +62,7 @@ public class MapViewTests
                 new ContentDocument(
                     CatalogLoader.CorePackId,
                     "defs/territories/yard.jsonc",
-                    """{ "defName": "Yard" }"""),
+                    """{ "defName": "Yard", "travelMinutes": 1 }"""),
                 new ContentDocument(
                     CatalogLoader.CorePackId,
                     "localizations/ru.jsonc",
diff --git a/tests/HSchool.Content.Tests/PatchTests.cs b/tests/HSchool.Content.Tests/PatchTests.cs
index 7ee0d11..640da59 100644
--- a/tests/HSchool.Content.Tests/PatchTests.cs
+++ b/tests/HSchool.Content.Tests/PatchTests.cs
@@ -74,7 +74,8 @@ public class PatchTests
                     {
                       "defName": "Office",
                       "slots": [ { "key": "seat", "thing": "Chair" } ],
-                      "works": ["TeachLesson", "WalkSchool"]
+                      "works": ["TeachLesson", "WalkSchool"],
+                      "travelMinutes": 1
                     }
                     """),
                 PackDocuments.Patch(
diff --git a/tests/HSchool.Content.Tests/VanillaCoreTests.cs b/tests/HSchool.Content.Tests/VanillaCoreTests.cs
index b0cfa25..ff8e4f1 100644
--- a/tests/HSchool.Content.Tests/VanillaCoreTests.cs
+++ b/tests/HSchool.Content.Tests/VanillaCoreTests.cs
@@ -57,6 +57,13 @@ public class VanillaCoreTests
         Assert.DoesNotContain(map.Rooms, room => room.Label is "1A" or "1B" or "2A" or "2B");
         Assert.Equal(16, map.Rooms.Single(room => room.Id == "classroom-101").Seats);
         Assert.Empty(map.Rooms.Single(room => room.Id == "classroom-101").Slots);
+        Assert.Equal(0.5f, catalog.Rooms["Classroom"].TravelMinutes);
+        Assert.Equal(1.5f, catalog.Rooms["Corridor"].TravelMinutes);
+        Assert.Equal(1.5f, catalog.Rooms["Stairwell"].TravelMinutes);
+        Assert.Equal(1f, catalog.Rooms["EntranceHall"].TravelMinutes);
+        Assert.Equal(3f, catalog.Territories["SchoolYard"].TravelMinutes);
+        Assert.Equal(4, catalog.Traits["Diligent"].CommuteMinutes);
+        Assert.Equal(-4, catalog.Traits["Lazy"].CommuteMinutes);
     }
 
     /// <summary>
diff --git a/tests/HSchool.Simulation.Tests/GameClockTests.cs b/tests/HSchool.Simulation.Tests/GameClockTests.cs
index 3afcec8..bd7a7b9 100644
--- a/tests/HSchool.Simulation.Tests/GameClockTests.cs
+++ b/tests/HSchool.Simulation.Tests/GameClockTests.cs
@@ -120,6 +120,19 @@ public class GameClockTests
         Assert.Equal(DateTimeKind.Utc, clock.Time.Kind);
     }
 
+    [Fact]
+    public void JumpTo_MovesTheCalendarWithoutTicking()
+    {
+        var clock = new GameClock(Start) { IsRunning = false };
+        var target = new DateTime(2012, 4, 9, 6, 0, 0, DateTimeKind.Utc);
+
+        clock.JumpTo(target);
+
+        Assert.Equal(target, clock.Time);
+        Assert.Equal(DateTimeKind.Utc, clock.Time.Kind);
+        Assert.False(clock.IsRunning);
+    }
+
     [Fact]
     public void StartDateOutsideTheSupportedRange_Throws()
     {
diff --git a/tests/HSchool.Simulation.Tests/HSchool.Simulation.Tests.csproj b/tests/HSchool.Simulation.Tests/HSchool.Simulation.Tests.csproj
index 5738cea..d270cf9 100644
--- a/tests/HSchool.Simulation.Tests/HSchool.Simulation.Tests.csproj
+++ b/tests/HSchool.Simulation.Tests/HSchool.Simulation.Tests.csproj
@@ -16,6 +16,8 @@
     <ProjectReference Include="..\..\src\HSchool.Simulation\HSchool.Simulation.csproj" />
     <ProjectReference Include="..\..\src\HSchool.Content\HSchool.Content.csproj" />
     <ProjectReference Include="..\..\src\HSchool.People\HSchool.People.csproj" />
+    <ProjectReference Include="..\..\src\HSchool.Schedule\HSchool.Schedule.csproj" />
+    <ProjectReference Include="..\..\src\HSchool.Ai\HSchool.Ai.csproj" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/tests/HSchool.Simulation.Tests/PresenceTests.cs b/tests/HSchool.Simulation.Tests/PresenceTests.cs
new file mode 100644
index 0000000..a9e4f75
--- /dev/null
+++ b/tests/HSchool.Simulation.Tests/PresenceTests.cs
@@ -0,0 +1,323 @@
+using HSchool.Ai;
+using HSchool.Content;
+using HSchool.People;
+using HSchool.Schedule;
+
+namespace HSchool.Simulation.Tests;
+
+public class PresenceTests
+{
+    private static readonly DateTime TuesdayMorning = new(2012, 4, 3, 6, 0, 0, DateTimeKind.Utc);
+    private static readonly float Cap = 100_000f;
+
+    [Fact]
+    public void SundayAndHoliday_LeaveTheCampusEmpty()
+    {
+        var (catalog, map) = Vanilla();
+        var sunday = new DateTime(2012, 4, 8, 10, 0, 0, DateTimeKind.Utc);
+        using var onSunday = Open(catalog, map, sunday, seed: 1);
+        onSunday.Tick(0.2d, 5d);
+        Assert.True(onSunday.IsCampusEmpty());
+        Assert.All(onSunday.CapturePresence(), row => Assert.Null(row.NodeId));
+
+        var holiday = new DateTime(2012, 6, 1, 10, 0, 0, DateTimeKind.Utc);
+        using var onHoliday = Open(catalog, map, holiday, seed: 1);
+        onHoliday.Tick(0.2d, 5d);
+        Assert.True(onHoliday.IsCampusEmpty());
+    }
+
+    [Fact]
+    public void ClassWithoutLessons_StaysAway_TeacherWithAnotherClassComes()
+    {
+        var (catalog, map) = Vanilla();
+        var roster = RosterGenerator.Generate(catalog, map, schoolSeed: 1, "Slavic", TuesdayMorning);
+        var pool = ApplicantPool.Create(catalog, roster, schoolSeed: 1, "Slavic", TuesdayMorning);
+        var idle = roster.Classes[0];
+        var busy = roster.Classes[1];
+        var hired = Staffing.Hire(catalog, map, roster, pool, pool.Applicants[0].Person.Id, Staffing.TeacherPosition, Cap);
+        Assert.Equal(StaffingError.None, hired.Error);
+
+        using var school = School.Create(1, "Два класса", TuesdayMorning, catalog, map);
+        school.InstallPeople(hired.Roster, seed: 1, "Slavic", hired.Pool);
+        school.SetTimetable(new Timetable(
+            [new LessonPlacement(busy.Id, "Mathematics", hired.Roster.People.First(person => person.IsStaff).Id, busy.RoomId, Day: 1, Period: 1)],
+            []));
+        school.ConfigurePresence(weekDays: 5, maxDecisionsPerTick: 10_000);
+
+        AdvanceTo(school, new DateTime(2012, 4, 3, 8, 30, 0, DateTimeKind.Utc));
+
+        var teacherId = school.Roster!.People.First(person => person.IsStaff).Id;
+        var idlePupil = idle.PupilIds[0];
+        var byId = school.CapturePresence().ToDictionary(row => row.PersonId, StringComparer.Ordinal);
+        Assert.Null(byId[idlePupil].NodeId);
+        Assert.NotNull(byId[teacherId].NodeId);
+    }
+
+    [Fact]
+    public void FirstLesson_PutsThePupilInTheirHomeroom()
+    {
+        var (school, homeroom, pupilId) = StaffedFirstFloorClass();
+        using (school)
+        {
+            AdvanceTo(school, new DateTime(2012, 4, 3, 8, 30, 0, DateTimeKind.Utc));
+
+            var row = school.CapturePresence().Single(item => item.PersonId == pupilId);
+            Assert.Equal(homeroom, row.NodeId);
+            Assert.Empty(row.Path);
+        }
+    }
+
+    [Fact]
+    public void PhysicalEducationAfterAClassroomLesson_ReachesTheGymOnTheBreak()
+    {
+        var (catalog, map) = Vanilla();
+        var walks = WalkGraph.Build(catalog, map);
+        Assert.Equal(6f, walks.Minutes("classroom-101", "gym-hall"));
+        Assert.True(walks.Minutes("classroom-101", "gym-hall") < catalog.DayFrame!.BreakMinutes);
+
+        var (school, _, pupilId) = StaffedFirstFloorClass();
+        using (school)
+        {
+            AdvanceTo(school, new DateTime(2012, 4, 3, 9, 25, 0, DateTimeKind.Utc));
+            var row = school.CapturePresence().Single(item => item.PersonId == pupilId);
+            Assert.Equal("gym-hall", row.NodeId);
+            Assert.Empty(row.Path);
+        }
+    }
+
+    [Fact]
+    public void SameSeedAndMap_YieldTheSamePlaces()
+    {
+        var (catalog, map) = Vanilla();
+        using var a = OpenStaffed(catalog, map, seed: 9);
+        using var b = OpenStaffed(catalog, map, seed: 9);
+        var until = new DateTime(2012, 4, 3, 9, 20, 0, DateTimeKind.Utc);
+        AdvanceTo(a, until);
+        AdvanceTo(b, until);
+
+        Assert.Equal(Fingerprint(a.CapturePresence()), Fingerprint(b.CapturePresence()));
+    }
+
+    [Fact]
+    public void SaveAndLoadMidBreak_DoesNotTeleport()
+    {
+        var (catalog, map) = Vanilla();
+        using var live = OpenStaffed(catalog, map, seed: 4);
+        AdvanceTo(live, new DateTime(2012, 4, 3, 9, 18, 0, DateTimeKind.Utc));
+        var snapshot = live.CapturePresence();
+        Assert.Contains(snapshot, row => row.NodeId is not null && (row.Path.Count > 0 || row.RemainingMinutes > 0));
+
+        using var loaded = School.Load(2, "Сейв", live.Clock.Time, running: true, speedIndex: 0, catalog, map);
+        loaded.InstallPeople(live.Roster!, seed: 4, "Slavic", live.Applicants);
+        loaded.SetTimetable(live.Timetable!);
+        loaded.ConfigurePresence(weekDays: 5, maxDecisionsPerTick: 10_000);
+        loaded.RestorePresence(snapshot);
+
+        Assert.Equal(Fingerprint(snapshot), Fingerprint(loaded.CapturePresence()));
+    }
+
+    [Fact]
+    public void SkipEmpty_FromSaturdayLandsOnMondaySix()
+    {
+        using var school = OpenEmpty(new DateTime(2012, 4, 7, 10, 0, 0, DateTimeKind.Utc));
+        var result = school.TrySkipEmpty();
+
+        Assert.True(result.Succeeded);
+        Assert.Equal(new DateTime(2012, 4, 9, 6, 0, 0, DateTimeKind.Utc), school.Clock.Time);
+    }
+
+    [Fact]
+    public void SkipEmpty_FromTuesdayNightLandsOnThatMorning()
+    {
+        using var school = OpenEmpty(new DateTime(2012, 4, 3, 3, 0, 0, DateTimeKind.Utc));
+        var result = school.TrySkipEmpty();
+
+        Assert.True(result.Succeeded);
+        Assert.Equal(new DateTime(2012, 4, 3, 6, 0, 0, DateTimeKind.Utc), school.Clock.Time);
+    }
+
+    [Fact]
+    public void SkipEmpty_FromTuesdayEveningLandsOnWednesday()
+    {
+        using var school = OpenEmpty(new DateTime(2012, 4, 3, 22, 0, 0, DateTimeKind.Utc));
+        var result = school.TrySkipEmpty();
+
+        Assert.True(result.Succeeded);
+        Assert.Equal(new DateTime(2012, 4, 4, 6, 0, 0, DateTimeKind.Utc), school.Clock.Time);
+    }
+
+    [Fact]
+    public void SkipEmpty_InTheWorkWindow_IsRejectedEvenWhenEmpty()
+    {
+        using var school = OpenEmpty(new DateTime(2012, 4, 3, 7, 0, 0, DateTimeKind.Utc));
+        Assert.True(school.IsCampusEmpty());
+
+        var result = school.TrySkipEmpty();
+
+        Assert.False(result.Succeeded);
+        Assert.Equal(SkipEmptyError.InWorkWindow, result.Error);
+        Assert.Equal(new DateTime(2012, 4, 3, 7, 0, 0, DateTimeKind.Utc), school.Clock.Time);
+    }
+
+    [Fact]
+    public void SkipEmpty_SchoolWithoutTeachers_StillHasAWorkDay()
+    {
+        using var school = OpenEmpty(new DateTime(2012, 4, 3, 10, 0, 0, DateTimeKind.Utc));
+        Assert.Equal(0, school.Roster!.People.Count(person => person.IsStaff));
+
+        var result = school.TrySkipEmpty();
+
+        Assert.False(result.Succeeded);
+        Assert.Equal(SkipEmptyError.InWorkWindow, result.Error);
+    }
+
+    [Fact]
+    public void SkipEmpty_OverSummer_RunsFirstSeptemberIntake()
+    {
+        var start = new DateTime(2012, 6, 1, 22, 0, 0, DateTimeKind.Utc);
+        using var school = OpenEmpty(start);
+        var before = school.Roster!;
+        var oldest = before.Classes.Max(row => row.Year);
+        var graduated = before.Classes
+            .Where(row => row.Year == oldest)
+            .SelectMany(row => row.PupilIds)
+            .ToHashSet(StringComparer.Ordinal);
+
+        var result = school.TrySkipEmpty();
+
+        Assert.True(result.Succeeded);
+        Assert.True(result.PeopleChanged);
+        Assert.Equal(new DateTime(2012, 9, 3, 6, 0, 0, DateTimeKind.Utc), school.Clock.Time);
+        Assert.Contains(school.Roster!.Classes, row => row.Year == 1);
+        Assert.DoesNotContain(school.Roster.People, person => graduated.Contains(person.Id));
+        Assert.Equal(before.People.Count(person => person.IsStudent), school.Roster.People.Count(person => person.IsStudent));
+    }
+
+    [Fact]
+    public void SkipEmpty_Week_MatchesALivedWeek()
+    {
+        var start = new DateTime(2012, 4, 6, 22, 0, 0, DateTimeKind.Utc);
+        var until = new DateTime(2012, 4, 9, 6, 0, 0, DateTimeKind.Utc);
+        using var skipped = OpenEmpty(start);
+        using var lived = OpenEmpty(start);
+
+        Assert.True(skipped.TrySkipEmpty().Succeeded);
+        while (lived.Clock.Time < until)
+        {
+            lived.Tick(0.2d, 5d);
+        }
+
+        Assert.Equal(until, skipped.Clock.Time);
+        Assert.Equal(until, lived.Clock.Time);
+        Assert.Equal(skipped.Applicants!.Week, lived.Applicants!.Week);
+        Assert.Equal(
+            skipped.Applicants.Applicants.Select(row => row.Person.Id),
+            lived.Applicants.Applicants.Select(row => row.Person.Id));
+        Assert.Equal(
+            skipped.Roster!.People.Select(person => person.Id).Order(StringComparer.Ordinal),
+            lived.Roster!.People.Select(person => person.Id).Order(StringComparer.Ordinal));
+        Assert.True(skipped.IsCampusEmpty());
+        Assert.True(lived.IsCampusEmpty());
+        Assert.Equal(Fingerprint(skipped.CapturePresence()), Fingerprint(lived.CapturePresence()));
+    }
+
+    [Fact]
+    public void Simulation_DoesNotReferenceSockets()
+    {
+        var names = typeof(School).Assembly.GetReferencedAssemblies().Select(assembly => assembly.Name!);
+        Assert.DoesNotContain(names, name => name.Contains("Sockets", StringComparison.OrdinalIgnoreCase));
+        Assert.DoesNotContain(names, name => name.Contains("AspNet", StringComparison.OrdinalIgnoreCase));
+    }
+
+    private static (School School, string Homeroom, string PupilId) StaffedFirstFloorClass()
+    {
+        var (catalog, map) = Vanilla();
+        var school = OpenStaffed(catalog, map, seed: 1);
+        var homeroomClass = school.Roster!.Classes.First(row =>
+            row.RoomId is "classroom-101" or "classroom-102" or "classroom-103" or "classroom-104");
+        var pupil = homeroomClass.PupilIds
+            .Select(id => school.Roster.People.First(person => person.Id == id))
+            .First(person => !person.Traits.Contains("Lazy"));
+        return (school, homeroomClass.RoomId, pupil.Id);
+    }
+
+    private static School OpenStaffed(DefCatalog catalog, MapLayout map, int seed)
+    {
+        var roster = RosterGenerator.Generate(catalog, map, seed, "Slavic", TuesdayMorning);
+        var pool = ApplicantPool.Create(catalog, roster, seed, "Slavic", TuesdayMorning);
+        var schoolClass = roster.Classes.First(row =>
+            row.RoomId is "classroom-101" or "classroom-102" or "classroom-103" or "classroom-104");
+        var school = School.Create(seed, "Присутствие", TuesdayMorning, catalog, map);
+        school.InstallPeople(roster, seed, "Slavic", pool);
+        school.SetTimetable(new Timetable(
+            [
+                new LessonPlacement(schoolClass.Id, "Mathematics", "t1", schoolClass.RoomId, Day: 1, Period: 1),
+                new LessonPlacement(schoolClass.Id, "PhysicalEducation", "t2", "gym-hall", Day: 1, Period: 2),
+            ],
+            []));
+        school.ConfigurePresence(weekDays: 5, maxDecisionsPerTick: 10_000);
+        return school;
+    }
+
+    private static School Open(DefCatalog catalog, MapLayout map, DateTime start, int seed)
+    {
+        var roster = RosterGenerator.Generate(catalog, map, seed, "Slavic", start);
+        var pool = ApplicantPool.Create(catalog, roster, seed, "Slavic", start);
+        var schoolClass = roster.Classes[0];
+        var school = School.Create(seed, "Присутствие", start, catalog, map);
+        school.InstallPeople(roster, seed, "Slavic", pool);
+        school.SetTimetable(new Timetable(
+            [new LessonPlacement(schoolClass.Id, "Mathematics", "t1", schoolClass.RoomId, Day: 0, Period: 1)],
+            []));
+        school.ConfigurePresence(weekDays: 5, maxDecisionsPerTick: 10_000);
+        return school;
+    }
+
+    private static School OpenEmpty(DateTime start)
+    {
+        var (catalog, map) = Vanilla();
+        var roster = RosterGenerator.Generate(catalog, map, schoolSeed: 1, "Slavic", start);
+        var pool = ApplicantPool.Create(catalog, roster, schoolSeed: 1, "Slavic", start);
+        var school = School.Create(1, "Пустая", start, catalog, map);
+        school.InstallPeople(roster, seed: 1, "Slavic", pool);
+        school.ConfigurePresence(weekDays: 5, maxDecisionsPerTick: 10_000);
+        return school;
+    }
+
+    private static void AdvanceTo(School school, DateTime until)
+    {
+        while (school.Clock.Time < until)
+        {
+            school.Tick(0.2d, 5d);
+        }
+    }
+
+    private static string Fingerprint(IReadOnlyList<PresenceSnapshot> rows) =>
+        string.Join(
+            "|",
+            rows.OrderBy(row => row.PersonId, StringComparer.Ordinal)
+                .Select(row =>
+                    $"{row.PersonId}:{row.NodeId ?? "-"}:{row.RemainingMinutes:0.###}:{row.DestinationId ?? "-"}:{(row.HeadingHome ? "1" : "0")}:{string.Join(",", row.Path)}"));
+
+    private static (DefCatalog Catalog, MapLayout Map) Vanilla()
+    {
+        var root = Path.Combine(AppContext.BaseDirectory, "vanilla");
+        var documents = new List<ContentDocument>();
+        foreach (var path in Directory.EnumerateFiles(root, "*.*", SearchOption.AllDirectories))
+        {
+            if (!path.EndsWith(".jsonc", StringComparison.OrdinalIgnoreCase)
+                && !path.EndsWith(".json", StringComparison.OrdinalIgnoreCase))
+            {
+                continue;
+            }
+
+            var relative = Path.GetRelativePath(root, path).Replace('\\', '/');
+            documents.Add(new ContentDocument(CatalogLoader.CorePackId, relative, File.ReadAllText(path)));
+        }
+
+        var catalog = new CatalogLoader().Load([CatalogLoader.CorePackId], documents);
+        var map = CatalogLoader.LastDefaultMap([CatalogLoader.CorePackId], documents);
+        Assert.NotNull(map);
+        return (catalog, map);
+    }
+}
diff --git a/tests/HSchool.Simulation.Tests/SchoolTests.cs b/tests/HSchool.Simulation.Tests/SchoolTests.cs
index fab7737..ac5ec53 100644
--- a/tests/HSchool.Simulation.Tests/SchoolTests.cs
+++ b/tests/HSchool.Simulation.Tests/SchoolTests.cs
@@ -50,10 +50,10 @@ public class SchoolTests
         {
             new ContentDocument("core", "defs/actions/sit.jsonc", """{ "defName": "Sit" }"""),
             new ContentDocument("core", "defs/things/chair.jsonc", """{ "defName": "Chair", "actions": ["Sit"] }"""),
-            new ContentDocument("core", "defs/territories/yard.jsonc", """{ "defName": "Yard" }"""),
+            new ContentDocument("core", "defs/territories/yard.jsonc", """{ "defName": "Yard", "travelMinutes": 1 }"""),
             new ContentDocument("core", "defs/buildings/main.jsonc", """{ "defName": "Main" }"""),
             new ContentDocument("core", "defs/floors/floor.jsonc", """{ "defName": "Floor" }"""),
-            new ContentDocument("core", "defs/rooms/office.jsonc", """{ "defName": "Office" }"""),
+            new ContentDocument("core", "defs/rooms/office.jsonc", """{ "defName": "Office", "travelMinutes": 1 }"""),
         };
         var catalog = loader.Load(["core"], documents);
         var map = new MapLayout