Timetable & scheduling.

Every other module in YESS hangs off the timetable. Attendance is taken against a period; the logbook is filed after a period; a substitution covers a period; a live class is scheduled into a period. So the timetable has to be right, and it has to be right for a whole school at once — not one class in isolation, but every section, every teacher, and every room, all consistent with each other.

Doing this by hand is the job nobody wants. A single teacher taught across three classes, a shared chemistry lab, a parallel elective band, a half-term where Form 5 sit mocks — a person with a spreadsheet can hold maybe one of those in their head at a time. YESS holds all of them at once. You describe the rules; the solver finds an arrangement that breaks none of the hard ones and bends as few of the soft ones as it can.

Describe the constraints once. Let the machine do the placing.

Before anything can be scheduled, the school has to declare the shape of its week. That happens at /dashboard/timetable/config. Here you set the cycle — daily, weekly, fortnightly or a custom cycle of up to fourteen days — the working days, the start and end of the teaching day, the default period duration (30 to 120 minutes), how many periods fall in a day, and where the breaks sit (each break is a name, the period it follows, and a length). Multi-campus schools configure this per campus — slots resolve in class → campus → school order, so a campus can run its own bell schedule without forking the whole school.

Once the shape is set, click Generate Slots and YESS builds the slot grid for you — every slot typed as a period, break or lunch, ordered, for every working day. You can still add, edit, or delete an individual slot by hand afterwards. The same screen holds the school's constraint ceilings (max consecutive periods per teacher, max periods per day per class, an over-capacity tolerance for rooms) and a solver-weight tuning panel — thirteen weighted factors, from protecting the lunch window and avoiding the same subject twice in a day to putting a practical after the theory, each of which you can dial up or reset to the engine default. Those weights are the knobs that make the generated timetable feel like yours rather than merely legal.

A timetable is only as good as the rules it respects. YESS gathers every rule in one place — /dashboard/timetable/constraints — across six tabs: Pairs, Subject caps, Teacher rules, Groups, Soft and Locked. Some are hard constraints the solver will never break; others are soft preferences it tries to honour and reports when it can't.

The auto-scheduler lives at /dashboard/timetable/scheduler — a three-step wizard: Select, Configure, Result. First you choose the scope. This is where YESS goes beyond a class-by-class tool: you can solve one class, a whole campus, a whole programme, or the whole school in a single run, then tick which sections to include.

In Configure, you set each subject's requirement — how many periods a week, the maximum per day, whether they should be consecutive or spread — alongside the ceilings for consecutive lessons per teacher and periods per day per class. The screen shows you, before you run, how many soft constraints are active and how many slots are locked (with a link straight back to the constraints hub) and runs a pre-flight readiness check that lists any blockers or warnings before you waste a solve.

Click Run Scheduler and the engine runs — entirely in your browser. Under the hood it opens an audit row, runs a multi-restart placement solver (it tries many arrangements — up to twenty restarts for a small scope — and keeps the best-scoring one), then runs an explainability pass that diagnoses anything it could not place. The Result step shows you the week grid with every placed period, a badge count of unscheduled items and conflicts, the conflict details, and a plain-language advisory for every unplaced lesson. When you are happy, click Apply Schedule — YESS clears the old periods for those sections and writes the new ones in one operation.

The grid itself lives at /dashboard/timetable/view, and it reads four ways: by class, by teacher, by room, or as a school overview — weekly or day by day. The same surface is also where you edit by hand: click an empty cell to place a period, choosing subject, teacher and room; the moment you do, YESS checks for a double-booked teacher, room, or section and flags the clash before it sticks.

Turn on the Free slots overlay to see, at a glance, where a teacher or room is genuinely free — invaluable when you are slotting in a make-up lesson. Lock a cell to protect it from accidental edits. Every manual change is recorded to an edit history, so a timetable that drifts over a term can always be traced back. When the week is settled, export it to CSV or print the grid for the staffroom wall.

A teacher calls in sick at 07:40. Their periods need cover before the first bell. At /dashboard/timetable/substitutions you open New Substitution, pick the absent teacher, choose the period that needs covering, and pick a substitute from a list filtered to staff who are genuinely free in that slot on that day — each shown with an "available" badge. The substitution is born pending; you Confirm it, then Mark complete once the lesson is covered, or Cancel if plans change. (Creating the substitution is itself the record of the absence — there is no separate absence toggle.)

When several teachers are out at once, work the whole queue from one screen: the /dashboard/timetable/clash-report shows every pending substitution in the next seven days, grouped by date. Pick covers row by row, or hit Auto-assign first available and let it walk the table — it assigns the first free substitute to each pending row and confirms it. Multi-campus schools can narrow the report to a single campus while school-wide cover stays visible.

A teacher who runs the Wednesday-morning staff briefing, or who is part-time and only in on Tuesdays and Thursdays, should never be placed against their off-periods. Record those windows at /dashboard/timetable/availability. Mark a teacher unavailable for a slot and the solver skips that combination during placement; it never has to be unpicked later.

Availability is set per term and can be replaced in bulk — useful at the start of a year when contracts and duty rosters change together. It is one of the inputs the solver weighs alongside the constraints hub, so the more honest your availability data, the fewer manual fixes the generated timetable needs.

Not every week is a normal week. Ramadan shortens the day; exam week replaces lessons with sittings; a summer intensive runs through the break. Variants, at /dashboard/timetable/variants, let you define an alternative schedule for a date range — name it, give it a code and a kind (Ramadan, summer intensive, winter short-day, exam week, revision week, orientation week, seasonal or custom), optionally scope it to particular classes or sections, and optionally override the slot grid for that period. A variant whose dates include today and that is marked active shows a "Live now" badge; the rest sit as drafts until you need them.

Holiday classes, at /dashboard/timetable/holiday-classes, are the sibling for teaching that happens during a break — exam prep, continuation, resit prep, academic recovery. Each window carries dates, an optional fee (with installment and parent-consent toggles), and a mandatory flag. Publish a window and it becomes visible to students and parents; if it carries a fee, enrolment can trigger an invoice automatically. Each window has its own roster you manage from its detail page.

A solver you cannot interrogate is a black box, and a black box has no place in a school's most load-bearing schedule. So every generation run is logged at /dashboard/timetable/runs. Each run carries a status — running, succeeded, partial, failed or aborted — and records its scope (class, section, campus, programme or school), when it started, how long it took, how many candidate arrangements it evaluated, how many conflicts it hit, how many items it could not place, the rejection codes that explain the failures (broken out by code), and which soft constraints it had to relax to find a legal answer.

This is the screen you open when a timetable comes out worse than you expected. "Last solve evaluated 47,000 candidates in 1.2 seconds, left two periods unplaced, and relaxed the staff-avoid rule twelve times" is a sentence you can act on — usually by loosening one constraint or freeing one teacher's availability, then running again. The run row is its own audit trail.