succesfull testing

controller/solver/grid.py

@@ -0,0 +1,54 @@
+"""
+Time-grid constants: days, slot definitions, lab double-slot pairs, and
+the special long-lecture slot. Pure data — no scheduling logic lives here.
+"""
+
+DAYS = ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday"]
+
+# Normal theory grid: 5 x 90-minute slots, 09:00-16:30, no lunch break.
+# Every placeable session (normal lecture, lab, or the special long
+# lecture) is expressed as one or more of these slot indices (0-4) for
+# clash-tracking purposes — see LONG_LECTURE_SLOT_INDEX below for why the
+# long lecture also uses index 0 despite rendering at a different clock time.
+TIME_SLOTS = [
+    {"label": "S1", "start": "09:00", "end": "10:30", "is_lunch": False},
+    {"label": "S2", "start": "10:30", "end": "12:00", "is_lunch": False},
+    {"label": "S3", "start": "12:00", "end": "13:30", "is_lunch": False},
+    {"label": "S4", "start": "13:30", "end": "15:00", "is_lunch": False},
+    {"label": "S5", "start": "15:00", "end": "16:30", "is_lunch": False},
+]
+
+# Indices into TIME_SLOTS that are real teaching slots (no lunch to skip
+# anymore, but kept for readability at call sites)
+TEACHING_SLOT_INDICES = [i for i, s in enumerate(TIME_SLOTS) if not s["is_lunch"]]
+
+# Consecutive pairs of normal slots usable as a 180-minute lab double-slot:
+# 10:30-13:30 (S2+S3) and 13:30-16:30 (S4+S5). Deliberately starts at slot
+# 1, not slot 0 — slot 0 (09:00-10:30) is left free for normal lectures and
+# the special long-lecture slot (see LONG_LECTURE_SLOT_INDEX below), so
+# labs never crowd out a batch's only long-lecture opportunity for the day.
+LAB_SLOT_PAIRS = [(1, 2), (3, 4)]
+
+# The special fixed slot for courses whose lecture is "2 hours once a
+# week": 08:30-10:30. This overlaps 09:00-10:30 (normal slot index 0) in
+# wall-clock time, so a long-lecture session is tracked as occupying slot
+# index 0 too (same key _is_free/_mark_busy use) — that's what makes it
+# correctly clash with anything else placed in normal slot 0 that day for
+# the same room/instructor/batch. duration_minutes on the session dict is
+# what distinguishes it from a normal 90-minute slot-0 session at render time.
+LONG_LECTURE_SLOT_INDEX = 0
+LONG_LECTURE_START = "08:30"
+LONG_LECTURE_END = "10:30"
+
+# Rows to render on every generated timetable grid: the special long-lecture
+# row first (it starts earliest, 08:30), then the 5 normal 90-minute rows.
+# Templates/xlsx_grid_helper key session lookups on (day, slot_index,
+# duration_minutes) using these rows' slot_index/duration_minutes pairs.
+DISPLAY_ROWS = [
+    {"label": "Long", "start": LONG_LECTURE_START, "end": LONG_LECTURE_END,
+     "slot_index": LONG_LECTURE_SLOT_INDEX, "duration_minutes": 120},
+] + [
+    {"label": s["label"], "start": s["start"], "end": s["end"],
+     "slot_index": i, "duration_minutes": 90}
+    for i, s in enumerate(TIME_SLOTS)
+]

controller/solver/phase1_general.py

@@ -0,0 +1,59 @@
+"""
+Phase 1: general courses (shared across every batch of a session).
+
+Simple strategy — small offering count, Tue/Thu preferred first. After
+placing everything, self-repair: any batch left with two general-course
+sessions in the same slot has the losing session unmarked and re-placed
+(scanning every day) until this phase's own sessions are clash-free.
+"""
+
+from . import grid
+
+
+def run(board, data, preferred_days=("Tuesday", "Thursday"), max_repair_attempts=20):
+    """Places every general-course offering's weekly lectures. Returns this phase's sessions."""
+    general = [o for o in data["offerings"] if o["course"]["is_general"]]
+    preferred_order = list(preferred_days) + [d for d in grid.DAYS if d not in preferred_days]
+    phase_start = len(board.sessions)
+
+    for offering in general:
+        course = offering["course"]
+        room_candidates = board.room_candidates(course["lecture_room_id"], board.classrooms)
+        for _ in range(course["lectures_per_week"]):
+            session = board.place_lecture(offering, room_candidates, preferred_order)
+            if session is None:
+                print(f"WARNING: could not place a lecture for general course {offering['course_id']} section {offering['section_id']}")
+
+    phase_sessions = board.sessions[phase_start:]
+    _repair_general_conflicts(board, data, phase_sessions, max_repair_attempts)
+    return phase_sessions
+
+
+def _repair_general_conflicts(board, data, phase_sessions, max_attempts):
+    """Moves general-course sessions that clash for a batch to a free slot on any day."""
+    from conflict_checker.student_conflict_checker import check_student_conflicts
+
+    any_day_order = list(grid.DAYS)
+    for _ in range(max_attempts):
+        conflicts = check_student_conflicts(phase_sessions)
+        if not conflicts:
+            return
+
+        # Re-place the last session involved in the first conflict; the
+        # other session(s) in that cell stay put.
+        losing_session = conflicts[0]["sessions"][-1]
+        offering = next(
+            o for o in data["offerings"]
+            if o["course_id"] == losing_session["course_id"] and o["section_id"] == losing_session["section_id"]
+        )
+        board.remove_session(losing_session)
+        phase_sessions.remove(losing_session)
+
+        room_candidates = board.room_candidates(offering["course"]["lecture_room_id"], board.classrooms)
+        new_session = board.place_lecture(offering, room_candidates, any_day_order)
+        if new_session is None:
+            print(f"WARNING: could not repair general-course conflict for {offering['course_id']} section {offering['section_id']}")
+            return
+        phase_sessions.append(new_session)
+
+    print("WARNING: general-course conflicts remained unresolved after max repair attempts")

controller/solver/phase2_labs.py

@@ -0,0 +1,116 @@
+"""
+Phase 2: labs.
+
+Slightly more advanced than Phase 1 — places every lab offering's weekly
+labs greedily first, against Phase 1's already-fixed placements. When a
+lab can't be placed, this backtracks *recursively*: it bumps an
+already-placed lab from earlier in this phase that shares the contested
+resource (same instructor or same lab room), and tries to re-place the
+stuck lab; if the bumped lab then can't find a new slot either, that
+bumped lab is itself backtracked the same way (bump one of *its*
+resource-sharing predecessors), and so on, until either everything
+settles or the attempt budget is exhausted. Phase 1's sessions are never
+touched — only Phase 2's own placements are ever moved.
+"""
+
+from . import grid
+
+MAX_BACKTRACK_ATTEMPTS = 2000
+
+
+def run(board, data):
+    """Places every lab offering's weekly labs. Returns this phase's sessions."""
+    phase_start = len(board.sessions)
+    offerings = [o for o in data["offerings"] if not o["course"]["is_general"] and o["course"]["labs_per_week"] > 0]
+
+    placed_so_far = []  # [(offering, session), ...] placed so far in this phase
+    attempts = [0]
+
+    for offering in offerings:
+        course = offering["course"]
+        room_candidates = board.room_candidates(course["lab_room_id"], board.labs)
+        for _ in range(course["labs_per_week"]):
+            session = _place_lab_with_backtracking(board, offering, room_candidates, placed_so_far, attempts)
+            if session is None:
+                print(f"WARNING: could not place a lab for course {offering['course_id']} section {offering['section_id']} ({offering['batch_codes']}) even after backtracking")
+            else:
+                placed_so_far.append((offering, session))
+
+    return board.sessions[phase_start:]
+
+
+def _place_lab_with_backtracking(board, offering, room_candidates, placed_so_far, attempts):
+    """
+    Tries the plain first-fit placement first; if that fails, tries
+    bumping each resource-sharing predecessor (most recent first) out of
+    the way and recursively re-seating it, backing out cleanly if a given
+    bump doesn't lead anywhere. Returns the newly placed session dict, or
+    None if no arrangement works within the attempt budget.
+    """
+    session = board.place_lab(offering, room_candidates, grid.DAYS)
+    if session is not None:
+        return session
+
+    # Snapshot the current candidates once — recursive calls will extend
+    # placed_so_far with their own successful re-seatings, but we only
+    # want to consider *this call's* view of what existed when we started.
+    candidate_room_ids = {r["room_id"] for r in room_candidates}
+    candidates = [
+        (other_offering, other_session)
+        for other_offering, other_session in placed_so_far
+        if _shares_contested_resource(offering, other_session, candidate_room_ids)
+    ]
+
+    for other_offering, other_session in reversed(candidates):
+        if attempts[0] >= MAX_BACKTRACK_ATTEMPTS:
+            return None
+        attempts[0] += 1
+
+        if (other_offering, other_session) not in placed_so_far:
+            # Already moved by an earlier (failed) branch of this search.
+            continue
+
+        placed_so_far.remove((other_offering, other_session))
+        board.remove_session(other_session)
+
+        session = board.place_lab(offering, room_candidates, grid.DAYS)
+        if session is not None:
+            other_room_candidates = board.room_candidates(other_offering["course"]["lab_room_id"], board.labs)
+            new_other_session = _place_lab_with_backtracking(board, other_offering, other_room_candidates, placed_so_far, attempts)
+            if new_other_session is not None:
+                placed_so_far.append((other_offering, new_other_session))
+                return session
+            # Could not reseat the bumped lab even with recursion — undo
+            # our placement and put the bump back exactly as it was.
+            board.remove_session(session)
+            placed_so_far.append((other_offering, _restore_lab(board, other_offering, other_session)))
+            continue
+
+        # Bumping didn't free a usable slot for `offering` — restore and
+        # try the next candidate.
+        placed_so_far.append((other_offering, _restore_lab(board, other_offering, other_session)))
+
+    return None
+
+
+def _restore_lab(board, offering, session):
+    """Re-marks and re-adds a lab session dict exactly as it was."""
+    room = board.data["rooms_by_id"][session["room_id"]]
+    for slot_index in session["slot_indices"]:
+        board.mark_busy(session["day"], slot_index, session["room_id"], session["instructor_code"], session["batch_codes"])
+    return board.add_session(offering, session["day"], session["slot_indices"], room)
+
+
+def _shares_contested_resource(offering, other_session, candidate_room_ids):
+    """
+    True if bumping other_session could plausibly free a slot offering
+    needs: shares the instructor, a usable lab room, or one of offering's
+    own batches (a batch can only be in one place at a time, so another
+    session competing for that batch's slot is a real contested resource
+    too, not just instructor/room).
+    """
+    if other_session["instructor_code"] == offering["instructor_code"]:
+        return True
+    if other_session["room_id"] in candidate_room_ids:
+        return True
+    return bool(set(other_session["batch_codes"]) & set(offering["batch_codes"]))

controller/solver/phase3_remaining.py

@@ -0,0 +1,193 @@
+"""
+Phase 3: remaining (non-general) theory courses — batch by batch, with
+recursive multi-bump backtracking.
+
+Processes batches in sorted batch_code order. Each batch must be fully
+placed with zero conflicts before moving to the next batch. If a batch's
+courses can't all be placed, this backtracks into *earlier, already-
+completed Phase 3 batches*: it bumps sessions that share a contested
+resource (same instructor, same room, or same batch) with the stuck
+offering out of the way — trying combinations of more than one bumped
+session where a single bump isn't enough — then reseats every bumped
+session afterward (recursively backtracking again if a reseat itself gets
+stuck), until either everything settles or the attempt budget is
+exhausted.
+
+Phase 1 and Phase 2 sessions are never touched — only sessions this phase
+itself placed for earlier batches are ever reopened.
+"""
+
+from . import grid
+
+MAX_BACKTRACK_ATTEMPTS = 5000
+MAX_SIMULTANEOUS_BUMPS = 3
+
+
+def run(board, data):
+    """
+    Places every remaining (non-general) theory offering's weekly
+    lectures, batch by batch. Returns this phase's sessions.
+    """
+    phase_start = len(board.sessions)
+    offerings = [o for o in data["offerings"] if not o["course"]["is_general"]]
+
+    # placed_so_far: flat list of (offering, session) for every session
+    # this phase has placed so far (across all completed batches) — the
+    # pool backtracking is allowed to bump from.
+    placed_so_far = []
+    attempts = [0]
+
+    for batch in sorted(data["batches"], key=lambda b: b["batch_code"]):
+        batch_code = batch["batch_code"]
+        batch_offerings = [o for o in offerings if batch_code in o["batch_codes"]]
+        # Place the most slot-constrained offerings first (long-lecture
+        # courses can only ever use slot 0, so they have the fewest
+        # options) — this way flexible 90-min courses fill in around them
+        # instead of greedily grabbing slot 0 first and starving a
+        # long-lecture course that has nowhere else to go.
+        batch_offerings.sort(key=lambda o: 0 if o["course"]["lecture_duration_minutes"] == 120 else 1)
+
+        for offering in batch_offerings:
+            course = offering["course"]
+            room_candidates = board.room_candidates(course["lecture_room_id"], board.classrooms)
+            for _ in range(course["lectures_per_week"]):
+                session = _place_lecture_with_backtracking(board, offering, room_candidates, placed_so_far, attempts)
+                if session is None:
+                    print(
+                        f"WARNING: could not place a lecture for course {offering['course_id']} "
+                        f"section {offering['section_id']} (batch {batch_code}) even after backtracking"
+                    )
+                else:
+                    placed_so_far.append((offering, session))
+
+    return board.sessions[phase_start:]
+
+
+def _place_lecture_with_backtracking(board, offering, room_candidates, placed_so_far, attempts):
+    """
+    Tries the plain first-fit placement first; if that fails, tries
+    bumping *combinations* of resource-sharing predecessors out of the way
+    (starting with one at a time, then pairs, up to MAX_SIMULTANEOUS_BUMPS
+    together) until `offering` fits, then reseats every bumped session
+    (recursively backtracking again if a reseat itself gets stuck).
+    Returns the newly placed session dict, or None if no arrangement works
+    within the attempt budget.
+    """
+    session = board.place_lecture(offering, room_candidates, grid.DAYS)
+    if session is not None:
+        return session
+
+    candidate_room_ids = {r["room_id"] for r in room_candidates}
+    usable_slot_indices = {grid.LONG_LECTURE_SLOT_INDEX} if offering["course"]["lecture_duration_minutes"] == 120 else set(grid.TEACHING_SLOT_INDICES)
+    candidates = [
+        (other_offering, other_session)
+        for other_offering, other_session in placed_so_far
+        if _shares_contested_resource(offering, other_session, candidate_room_ids, usable_slot_indices)
+    ]
+    # Most recently placed first — later placements are more likely to be
+    # "loose" (easier to reseat) than earlier, already-settled ones.
+    candidates.reverse()
+
+    for bump_count in range(1, min(MAX_SIMULTANEOUS_BUMPS, len(candidates)) + 1):
+        result = _try_bump_combinations(board, offering, room_candidates, placed_so_far, attempts, candidates, bump_count)
+        if result is not None:
+            return result
+        if attempts[0] >= MAX_BACKTRACK_ATTEMPTS:
+            return None
+
+    return None
+
+
+def _try_bump_combinations(board, offering, room_candidates, placed_so_far, attempts, candidates, bump_count):
+    """
+    Tries every way of picking `bump_count` candidates (in order) to bump
+    simultaneously, retrying `offering`'s placement after each bump.
+    Returns the newly placed session on success (with all bumped sessions
+    reseated), or None if no combination of this size works.
+    """
+    from itertools import combinations
+
+    for combo in combinations(range(len(candidates)), bump_count):
+        if attempts[0] >= MAX_BACKTRACK_ATTEMPTS:
+            return None
+
+        chosen = [candidates[i] for i in combo]
+        if any((o, s) not in placed_so_far for o, s in chosen):
+            # One of these was already moved by an earlier failed branch.
+            continue
+
+        bumped = []
+        for other_offering, other_session in chosen:
+            attempts[0] += 1
+            placed_so_far.remove((other_offering, other_session))
+            board.remove_session(other_session)
+            bumped.append((other_offering, other_session))
+
+        session = board.place_lecture(offering, room_candidates, grid.DAYS)
+        if session is not None:
+            if _reseat_all(board, placed_so_far, attempts, bumped):
+                return session
+            # Reseating some bumped session failed even with recursion —
+            # undo our placement and restore everything bumped this round.
+            board.remove_session(session)
+            for other_offering, other_session in bumped:
+                placed_so_far.append((other_offering, _restore_session(board, other_offering, other_session)))
+            continue
+
+        # This combination didn't free a usable slot — restore everything
+        # bumped this round and try the next combination.
+        for other_offering, other_session in bumped:
+            placed_so_far.append((other_offering, _restore_session(board, other_offering, other_session)))
+
+    return None
+
+
+def _reseat_all(board, placed_so_far, attempts, bumped):
+    """
+    Reseats every (offering, session) in `bumped` (each currently removed
+    from the board), backtracking recursively if needed. All-or-nothing:
+    on any failure, every session reseated so far in this attempt is
+    removed again and `bumped` remains fully un-seated (the caller is
+    responsible for restoring them to their original slots).
+    """
+    reseated = []
+    for other_offering, other_session in bumped:
+        other_room_candidates = board.room_candidates(other_offering["course"]["lecture_room_id"], board.classrooms)
+        new_session = _place_lecture_with_backtracking(board, other_offering, other_room_candidates, placed_so_far, attempts)
+        if new_session is None:
+            for reseated_offering, reseated_session in reseated:
+                placed_so_far.remove((reseated_offering, reseated_session))
+                board.remove_session(reseated_session)
+            return False
+        reseated.append((other_offering, new_session))
+        placed_so_far.append((other_offering, new_session))
+    return True
+
+
+def _restore_session(board, offering, session):
+    """Re-marks and re-adds a session dict exactly as it was, at the same day/slots/room."""
+    room = board.data["rooms_by_id"][session["room_id"]]
+    for slot_index in session["slot_indices"]:
+        board.mark_busy(session["day"], slot_index, session["room_id"], session["instructor_code"], session["batch_codes"])
+    return board.add_session(
+        offering, session["day"], session["slot_indices"], room,
+        is_long_lecture=(session["duration_minutes"] == 120),
+    )
+
+
+def _shares_contested_resource(offering, other_session, candidate_room_ids, usable_slot_indices):
+    """
+    True if bumping other_session could plausibly free a slot `offering`
+    can actually use: other_session must occupy at least one slot index
+    `offering` is eligible for, AND share the instructor, a usable room,
+    or (crucially) one of offering's own batches — a batch can only be in
+    one place at a time, so another course competing for the *same batch's*
+    slot-0 time is just as real a contested resource as instructor/room.
+    """
+    if not any(slot_index in usable_slot_indices for slot_index in other_session["slot_indices"]):
+        return False
+    if other_session["instructor_code"] == offering["instructor_code"]:
+        return True
+    if other_session["room_id"] in candidate_room_ids:
+        return True
+    return bool(set(other_session["batch_codes"]) & set(offering["batch_codes"]))

controller/solver/placement_board.py

@@ -0,0 +1,171 @@
+"""
+PlacementBoard: shared clash-tracking state and low-level placement
+primitives. Owns the room/instructor/batch busy-maps and the accumulated
+session list. Has zero scheduling policy of its own — every phase module
+(phase1_general, phase2_labs, phase3_remaining) reads and writes the same
+board, which is what makes each later phase automatically see earlier
+phases' placements as fixed/locked.
+"""
+
+from . import grid
+
+
+class PlacementBoard:
+    def __init__(self, data):
+        self.data = data
+        self.classrooms = [r for r in data["rooms"] if r["room_type"] == "classroom"]
+        self.labs = [r for r in data["rooms"] if r["room_type"] == "lab"]
+
+        # busy[(day, slot_index)] -> set of keys already occupied
+        self.room_busy = {}
+        self.instructor_busy = {}
+        self.batch_busy = {}
+
+        self.sessions = []
+
+    # -- serialization -----------------------------------------------------
+
+    def to_state(self):
+        """Serializes accumulated sessions + busy-maps to a JSON-able dict."""
+        def _dump_busy(busy_map):
+            return {f"{day}|{slot_index}": sorted(values) for (day, slot_index), values in busy_map.items()}
+
+        return {
+            "sessions": self.sessions,
+            "room_busy": _dump_busy(self.room_busy),
+            "instructor_busy": _dump_busy(self.instructor_busy),
+            "batch_busy": _dump_busy(self.batch_busy),
+        }
+
+    @classmethod
+    def from_state(cls, data, state):
+        """Rebuilds a PlacementBoard from a dict previously produced by to_state()."""
+        def _load_busy(dumped):
+            busy = {}
+            for key, values in dumped.items():
+                day, slot_index = key.rsplit("|", 1)
+                busy[(day, int(slot_index))] = set(values)
+            return busy
+
+        board = cls(data)
+        board.sessions = list(state["sessions"])
+        board.room_busy = _load_busy(state["room_busy"])
+        board.instructor_busy = _load_busy(state["instructor_busy"])
+        board.batch_busy = _load_busy(state["batch_busy"])
+        return board
+
+    # -- clash-tracking primitives ------------------------------------------
+
+    def is_free(self, day, slot_index, room_id, instructor_code, batch_codes):
+        key = (day, slot_index)
+        if room_id in self.room_busy.get(key, set()):
+            return False
+        if instructor_code in self.instructor_busy.get(key, set()):
+            return False
+        if any(b in self.batch_busy.get(key, set()) for b in batch_codes):
+            return False
+        return True
+
+    def mark_busy(self, day, slot_index, room_id, instructor_code, batch_codes):
+        key = (day, slot_index)
+        self.room_busy.setdefault(key, set()).add(room_id)
+        self.instructor_busy.setdefault(key, set()).add(instructor_code)
+        self.batch_busy.setdefault(key, set()).update(batch_codes)
+
+    def unmark_busy(self, day, slot_index, room_id, instructor_code, batch_codes):
+        key = (day, slot_index)
+        self.room_busy.get(key, set()).discard(room_id)
+        self.instructor_busy.get(key, set()).discard(instructor_code)
+        for b in batch_codes:
+            self.batch_busy.get(key, set()).discard(b)
+
+    def room_candidates(self, preferred_room_id, room_pool):
+        """Preferred room first, then the rest of the same-type pool."""
+        preferred = self.data["rooms_by_id"].get(preferred_room_id)
+        rest = [r for r in room_pool if r["room_id"] != preferred_room_id]
+        return ([preferred] if preferred else []) + rest
+
+    # -- session creation ----------------------------------------------------
+
+    def add_session(self, offering, day, slot_indices, room, is_long_lecture=False):
+        course = offering["course"]
+        if is_long_lecture:
+            start, end = grid.LONG_LECTURE_START, grid.LONG_LECTURE_END
+            duration_minutes = 120
+            session_type = "theory"
+        else:
+            start = grid.TIME_SLOTS[slot_indices[0]]["start"]
+            end = grid.TIME_SLOTS[slot_indices[-1]]["end"]
+            duration_minutes = 90 * len(slot_indices)
+            session_type = "lab" if len(slot_indices) > 1 else "theory"
+        session = {
+            "day": day,
+            "slot_indices": slot_indices,
+            "start": start,
+            "end": end,
+            "duration_minutes": duration_minutes,
+            "course_id": offering["course_id"],
+            "course_name": course["course_name"],
+            "course_type": session_type,
+            "is_general": course["is_general"],
+            "section_id": offering["section_id"],
+            "instructor_code": offering["instructor_code"],
+            "instructor_name": offering["instructor_name"],
+            "room_id": room["room_id"],
+            "room_name": room["room_name"],
+            "batch_codes": offering["batch_codes"],
+        }
+        self.sessions.append(session)
+        return session
+
+    def remove_session(self, session):
+        """Unmarks a previously placed session's slots and removes it from self.sessions."""
+        for slot_index in session["slot_indices"]:
+            self.unmark_busy(
+                session["day"], slot_index,
+                session["room_id"], session["instructor_code"], session["batch_codes"],
+            )
+        self.sessions.remove(session)
+
+    # -- placement helpers shared by phase modules --------------------------
+
+    def place_theory_session(self, offering, room_candidates, day_order):
+        """Finds and locks a free normal 90-minute single-slot session; returns the session dict or None."""
+        for day in day_order:
+            for slot_index in grid.TEACHING_SLOT_INDICES:
+                for room in room_candidates:
+                    if self.is_free(day, slot_index, room["room_id"], offering["instructor_code"], offering["batch_codes"]):
+                        self.mark_busy(day, slot_index, room["room_id"], offering["instructor_code"], offering["batch_codes"])
+                        return self.add_session(offering, day, [slot_index], room)
+        return None
+
+    def place_long_lecture(self, offering, room_candidates, day_order):
+        """
+        Finds and locks a free 08:30-10:30 long-lecture session. Occupies
+        the same clash-tracking slot index as normal slot 0 since they
+        overlap in wall-clock time. Returns the session dict or None.
+        """
+        for day in day_order:
+            for room in room_candidates:
+                if self.is_free(day, grid.LONG_LECTURE_SLOT_INDEX, room["room_id"], offering["instructor_code"], offering["batch_codes"]):
+                    self.mark_busy(day, grid.LONG_LECTURE_SLOT_INDEX, room["room_id"], offering["instructor_code"], offering["batch_codes"])
+                    return self.add_session(offering, day, [grid.LONG_LECTURE_SLOT_INDEX], room, is_long_lecture=True)
+        return None
+
+    def place_lecture(self, offering, room_candidates, day_order):
+        """Dispatches to the long (120-min) or normal (90-min) lecture placement based on the course's lecture_duration_minutes."""
+        if offering["course"]["lecture_duration_minutes"] == 120:
+            return self.place_long_lecture(offering, room_candidates, day_order)
+        return self.place_theory_session(offering, room_candidates, day_order)
+
+    def place_lab(self, offering, room_candidates, day_order):
+        """Finds and locks a free 180-minute lab double-slot session; returns the session dict or None."""
+        for day in day_order:
+            for slot_a, slot_b in grid.LAB_SLOT_PAIRS:
+                for room in room_candidates:
+                    if self.is_free(day, slot_a, room["room_id"], offering["instructor_code"], offering["batch_codes"]) and \
+                       self.is_free(day, slot_b, room["room_id"], offering["instructor_code"], offering["batch_codes"]):
+                        self.mark_busy(day, slot_a, room["room_id"], offering["instructor_code"], offering["batch_codes"])
+                        self.mark_busy(day, slot_b, room["room_id"], offering["instructor_code"], offering["batch_codes"])
+                        return self.add_session(offering, day, [slot_a, slot_b], room)
+        return None

controller/template_controller.py

@@ -1,24 +1,23 @@
 """
-Loads dummy CSV data and builds a clash-free schedule of sessions that all
-five templates/*-wise template modules render from.
+Loads dummy CSV data and exposes a thin Scheduler facade over the solver
+engine in controller/solver/ (grid constants, PlacementBoard, and one
+module per phase — phase1_general, phase2_labs, phase3_remaining).
 
-Scheduling is done in three sequential, independently-verified phases (see
-app/template_generator.py for the orchestration + per-phase conflict
-checks). Each phase's placements are locked before the next phase starts:
-once a (day, slot, room/instructor/batch) combination is marked busy by an
-earlier phase, later phases can never reuse it.
+Scheduling is done in three sequential, independently-verified phases, each
+with its own tailored strategy (see controller/solver/phase*_*.py for the
+per-phase logic). Each phase's placements are locked before the next phase
+starts: once a (day, slot, room/instructor/batch) combination is marked
+busy by an earlier phase, later phases can never reuse it — except Phase
+3, which is allowed to backtrack and reopen *its own* earlier batches
+(never Phase 1 or Phase 2) when a later batch can't otherwise be placed.
 
   1. General courses (shared across every batch of a session), preferring
-     Tuesday/Thursday first. Each offering gets `lectures_per_week`
-     sessions. If two general courses still land in the same slot for a
-     batch, the losing session is moved to another day/slot until this
-     phase is clash-free (see `phase_1_general_courses`).
-  2. Labs: each offering gets `labs_per_week` 180-minute / double-slot
-     sessions, in lab rooms only, scheduled against Phase 1's fixed
-     placements plus labs placed so far this phase.
+     Tuesday/Thursday first, self-repaired until clash-free.
+  2. Labs, scheduled against Phase 1's fixed placements, then self-repaired
+     for lab-vs-lab clashes within Phase 2 only.
   3. Remaining (non-general) theory sessions, scheduled batch by batch in
-     sorted batch_code order: for each batch, every one of its remaining
-     offerings is placed and locked before the next batch is considered.
+     sorted batch_code order, with backtracking into earlier Phase 3
+     batches when a later batch can't otherwise fit.
 
 Time grid: 5 normal 90-minute slots, 09:00-16:30, no lunch break. Labs use
 180-minute double-slots (09:00-12:00 and 12:00-15:00). A course whose
@@ -34,55 +33,15 @@ preferred one is busy for that day/slot.
 import csv
 import os
 
+from solver.grid import (  # noqa: F401  (re-exported for templates/backward compatibility)
+    DAYS, TIME_SLOTS, TEACHING_SLOT_INDICES, LAB_SLOT_PAIRS,
+    LONG_LECTURE_SLOT_INDEX, LONG_LECTURE_START, LONG_LECTURE_END, DISPLAY_ROWS,
+)
+from solver.placement_board import PlacementBoard
+from solver import phase1_general, phase2_labs, phase3_remaining
+
 DATA_DIR = os.path.join(os.path.dirname(os.path.dirname(os.path.abspath(__file__))), "data", "dummy")
 
-DAYS = ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday"]
-
-# Normal theory grid: 5 x 90-minute slots, 09:00-16:30, no lunch break.
-# Every placeable session (normal lecture, lab, or the special long
-# lecture) is expressed as one or more of these slot indices (0-4) for
-# clash-tracking purposes — see LONG_LECTURE_SLOT below for why the long
-# lecture also uses index 0 despite rendering at a different clock time.
-TIME_SLOTS = [
-    {"label": "S1", "start": "09:00", "end": "10:30", "is_lunch": False},
-    {"label": "S2", "start": "10:30", "end": "12:00", "is_lunch": False},
-    {"label": "S3", "start": "12:00", "end": "13:30", "is_lunch": False},
-    {"label": "S4", "start": "13:30", "end": "15:00", "is_lunch": False},
-    {"label": "S5", "start": "15:00", "end": "16:30", "is_lunch": False},
-]
-
-# Indices into TIME_SLOTS that are real teaching slots (no lunch to skip
-# anymore, but kept for readability at call sites)
-TEACHING_SLOT_INDICES = [i for i, s in enumerate(TIME_SLOTS) if not s["is_lunch"]]
-
-# Consecutive pairs of normal slots usable as a 180-minute lab double-slot:
-# 09:00-12:00 (S1+S2) and 12:00-15:00 (S3+S4).
-LAB_SLOT_PAIRS = [(0, 1), (2, 3)]
-
-# The special fixed slot for courses whose lecture is "2 hours once a
-# week": 08:30-10:30. This overlaps 09:00-10:30 (normal slot index 0) in
-# wall-clock time, so a long-lecture session is tracked as occupying slot
-# index 0 too (same key _is_free/_mark_busy use) — that's what makes it
-# correctly clash with anything else placed in normal slot 0 that day for
-# the same room/instructor/batch. duration_minutes on the session dict is
-# what distinguishes it from a normal 90-minute slot-0 session at render time.
-LONG_LECTURE_SLOT_INDEX = 0
-LONG_LECTURE_START = "08:30"
-LONG_LECTURE_END = "10:30"
-
-# Rows to render on every generated timetable grid: the special long-lecture
-# row first (it starts earliest, 08:30), then the 5 normal 90-minute rows.
-# Templates/xlsx_grid_helper key session lookups on (day, slot_index,
-# duration_minutes) using these rows' slot_index/duration_minutes pairs.
-DISPLAY_ROWS = [
-    {"label": "Long", "start": LONG_LECTURE_START, "end": LONG_LECTURE_END,
-     "slot_index": LONG_LECTURE_SLOT_INDEX, "duration_minutes": 120},
-] + [
-    {"label": s["label"], "start": s["start"], "end": s["end"],
-     "slot_index": i, "duration_minutes": 90}
-    for i, s in enumerate(TIME_SLOTS)
-]
-
 
 def _read_csv(relative_path):
     path = os.path.join(DATA_DIR, relative_path)
@@ -139,263 +98,44 @@ def load_data():
 
 
 class Scheduler:
-    """Greedy clash-free scheduler over rooms / instructors / batches."""
+    """
+    Thin facade over the solver engine: owns a PlacementBoard and
+    delegates each phase to its dedicated solver/phase*_*.py module.
+    Keeps the same public surface the rest of the app already relies on
+    (app/template_generator.py, controller/conflict_checker/*).
+    """
 
     def __init__(self, data):
         self.data = data
-        self.classrooms = [r for r in data["rooms"] if r["room_type"] == "classroom"]
-        self.labs = [r for r in data["rooms"] if r["room_type"] == "lab"]
+        self.board = PlacementBoard(data)
 
-        # busy[(day, slot_index)] -> set of keys already occupied
-        self.room_busy = {}
-        self.instructor_busy = {}
-        self.batch_busy = {}
-
-        self.sessions = []
+    @property
+    def sessions(self):
+        return self.board.sessions
 
     def to_state(self):
-        """
-        Serializes this scheduler's accumulated sessions and busy-maps to a
-        JSON-able dict, so a later process can resume exactly where this
-        one left off (used to run each phase as a separate CLI command).
-        """
-        def _dump_busy(busy_map):
-            return {f"{day}|{slot_index}": sorted(values) for (day, slot_index), values in busy_map.items()}
-
-        return {
-            "sessions": self.sessions,
-            "room_busy": _dump_busy(self.room_busy),
-            "instructor_busy": _dump_busy(self.instructor_busy),
-            "batch_busy": _dump_busy(self.batch_busy),
-        }
+        return self.board.to_state()
 
     @classmethod
     def from_state(cls, data, state):
-        """Rebuilds a Scheduler from a dict previously produced by to_state()."""
-        def _load_busy(dumped):
-            busy = {}
-            for key, values in dumped.items():
-                day, slot_index = key.rsplit("|", 1)
-                busy[(day, int(slot_index))] = set(values)
-            return busy
-
         scheduler = cls(data)
-        scheduler.sessions = list(state["sessions"])
-        scheduler.room_busy = _load_busy(state["room_busy"])
-        scheduler.instructor_busy = _load_busy(state["instructor_busy"])
-        scheduler.batch_busy = _load_busy(state["batch_busy"])
+        scheduler.board = PlacementBoard.from_state(data, state)
         return scheduler
 
-    def _is_free(self, day, slot_index, room_id, instructor_code, batch_codes):
-        key = (day, slot_index)
-        if room_id in self.room_busy.get(key, set()):
-            return False
-        if instructor_code in self.instructor_busy.get(key, set()):
-            return False
-        if any(b in self.batch_busy.get(key, set()) for b in batch_codes):
-            return False
-        return True
-
-    def _mark_busy(self, day, slot_index, room_id, instructor_code, batch_codes):
-        key = (day, slot_index)
-        self.room_busy.setdefault(key, set()).add(room_id)
-        self.instructor_busy.setdefault(key, set()).add(instructor_code)
-        self.batch_busy.setdefault(key, set()).update(batch_codes)
-
-    def _unmark_busy(self, day, slot_index, room_id, instructor_code, batch_codes):
-        key = (day, slot_index)
-        self.room_busy.get(key, set()).discard(room_id)
-        self.instructor_busy.get(key, set()).discard(instructor_code)
-        for b in batch_codes:
-            self.batch_busy.get(key, set()).discard(b)
-
-    def _room_candidates(self, preferred_room_id, room_pool):
-        """Preferred room first, then the rest of the same-type pool."""
-        preferred = self.data["rooms_by_id"].get(preferred_room_id)
-        rest = [r for r in room_pool if r["room_id"] != preferred_room_id]
-        return ([preferred] if preferred else []) + rest
-
-    def _add_session(self, offering, day, slot_indices, room, is_long_lecture=False):
-        course = offering["course"]
-        if is_long_lecture:
-            start, end = LONG_LECTURE_START, LONG_LECTURE_END
-            duration_minutes = 120
-            session_type = "theory"
-        else:
-            start = TIME_SLOTS[slot_indices[0]]["start"]
-            end = TIME_SLOTS[slot_indices[-1]]["end"]
-            duration_minutes = 90 * len(slot_indices)
-            session_type = "lab" if len(slot_indices) > 1 else "theory"
-        session = {
-            "day": day,
-            "slot_indices": slot_indices,
-            "start": start,
-            "end": end,
-            "duration_minutes": duration_minutes,
-            "course_id": offering["course_id"],
-            "course_name": course["course_name"],
-            "course_type": session_type,
-            "is_general": course["is_general"],
-            "section_id": offering["section_id"],
-            "instructor_code": offering["instructor_code"],
-            "instructor_name": offering["instructor_name"],
-            "room_id": room["room_id"],
-            "room_name": room["room_name"],
-            "batch_codes": offering["batch_codes"],
-        }
-        self.sessions.append(session)
-        return session
-
-    def _place_theory_session(self, offering, room_candidates, day_order):
-        """Finds and locks a free normal 90-minute single-slot session; returns the session dict or None."""
-        for day in day_order:
-            for slot_index in TEACHING_SLOT_INDICES:
-                for room in room_candidates:
-                    if self._is_free(day, slot_index, room["room_id"], offering["instructor_code"], offering["batch_codes"]):
-                        self._mark_busy(day, slot_index, room["room_id"], offering["instructor_code"], offering["batch_codes"])
-                        return self._add_session(offering, day, [slot_index], room)
-        return None
-
-    def _place_long_lecture(self, offering, room_candidates, day_order):
-        """
-        Finds and locks a free 08:30-10:30 long-lecture session (for
-        courses with lecture_duration_minutes=120). Occupies the same
-        clash-tracking slot index as normal slot 0 since they overlap in
-        wall-clock time (09:00-10:30). Returns the session dict or None.
-        """
-        for day in day_order:
-            for room in room_candidates:
-                if self._is_free(day, LONG_LECTURE_SLOT_INDEX, room["room_id"], offering["instructor_code"], offering["batch_codes"]):
-                    self._mark_busy(day, LONG_LECTURE_SLOT_INDEX, room["room_id"], offering["instructor_code"], offering["batch_codes"])
-                    return self._add_session(offering, day, [LONG_LECTURE_SLOT_INDEX], room, is_long_lecture=True)
-        return None
-
-    def _place_lecture(self, offering, room_candidates, day_order):
-        """Dispatches to the long (120-min) or normal (90-min) lecture placement based on the course's lecture_duration_minutes."""
-        if offering["course"]["lecture_duration_minutes"] == 120:
-            return self._place_long_lecture(offering, room_candidates, day_order)
-        return self._place_theory_session(offering, room_candidates, day_order)
-
-    def phase_1_general_courses(self, preferred_days=("Tuesday", "Thursday"), max_repair_attempts=20):
-        """
-        Places every general-course offering's weekly lectures, preferring
-        `preferred_days` first. Afterwards, self-repairs: any batch left
-        with two general-course sessions in the same slot has the losing
-        session unmarked and re-placed (scanning every day) until this
-        phase's own sessions are clash-free. Returns this phase's sessions.
-        """
-        general = [o for o in self.data["offerings"] if o["course"]["is_general"]]
-        preferred_order = list(preferred_days) + [d for d in DAYS if d not in preferred_days]
-        phase_start = len(self.sessions)
-
-        for offering in general:
-            course = offering["course"]
-            room_candidates = self._room_candidates(course["lecture_room_id"], self.classrooms)
-            for _ in range(course["lectures_per_week"]):
-                session = self._place_lecture(offering, room_candidates, preferred_order)
-                if session is None:
-                    print(f"WARNING: could not place a lecture for general course {offering['course_id']} section {offering['section_id']}")
-
-        phase_sessions = self.sessions[phase_start:]
-        self._repair_general_conflicts(phase_sessions, preferred_order, max_repair_attempts)
-        return phase_sessions
-
-    def _repair_general_conflicts(self, phase_sessions, day_order, max_attempts):
-        """Moves general-course sessions that clash for a batch to a free slot on any day."""
-        from conflict_checker.student_conflict_checker import check_student_conflicts
-
-        any_day_order = list(DAYS)
-        for _ in range(max_attempts):
-            conflicts = check_student_conflicts(phase_sessions)
-            if not conflicts:
-                return
-
-            # Re-place the last session involved in the first conflict; the
-            # other session(s) in that cell stay put.
-            losing_session = conflicts[0]["sessions"][-1]
-            offering = next(
-                o for o in self.data["offerings"]
-                if o["course_id"] == losing_session["course_id"] and o["section_id"] == losing_session["section_id"]
-            )
-            self._unmark_busy(
-                losing_session["day"], losing_session["slot_indices"][0],
-                losing_session["room_id"], losing_session["instructor_code"], losing_session["batch_codes"],
-            )
-            self.sessions.remove(losing_session)
-            phase_sessions.remove(losing_session)
-
-            room_candidates = self._room_candidates(offering["course"]["lecture_room_id"], self.classrooms)
-            new_session = self._place_lecture(offering, room_candidates, any_day_order)
-            if new_session is None:
-                print(f"WARNING: could not repair general-course conflict for {offering['course_id']} section {offering['section_id']}")
-                return
-            phase_sessions.append(new_session)
-
-        print("WARNING: general-course conflicts remained unresolved after max repair attempts")
+    def phase_1_general_courses(self):
+        return phase1_general.run(self.board, self.data)
 
     def phase_2_labs(self):
-        """
-        Places every lab offering's weekly labs into lab rooms, treating
-        Phase 1's placements (already marked busy) as fixed. Returns this
-        phase's sessions.
-        """
-        phase_start = len(self.sessions)
-        offerings = [o for o in self.data["offerings"] if not o["course"]["is_general"] and o["course"]["labs_per_week"] > 0]
-        for offering in offerings:
-            course = offering["course"]
-            room_candidates = self._room_candidates(course["lab_room_id"], self.labs)
-
-            for _ in range(course["labs_per_week"]):
-                placed = False
-                for day in DAYS:
-                    for slot_a, slot_b in LAB_SLOT_PAIRS:
-                        for room in room_candidates:
-                            if self._is_free(day, slot_a, room["room_id"], offering["instructor_code"], offering["batch_codes"]) and \
-                               self._is_free(day, slot_b, room["room_id"], offering["instructor_code"], offering["batch_codes"]):
-                                self._mark_busy(day, slot_a, room["room_id"], offering["instructor_code"], offering["batch_codes"])
-                                self._mark_busy(day, slot_b, room["room_id"], offering["instructor_code"], offering["batch_codes"])
-                                self._add_session(offering, day, [slot_a, slot_b], room)
-                                placed = True
-                                break
-                        if placed:
-                            break
-                    if placed:
-                        break
-                if not placed:
-                    print(f"WARNING: could not place a lab for course {offering['course_id']} section {offering['section_id']} ({offering['batch_codes']})")
-
-        return self.sessions[phase_start:]
+        return phase2_labs.run(self.board, self.data)
 
     def phase_3_remaining_courses(self):
-        """
-        Places every remaining (non-general) theory offering's weekly
-        lectures, batch by batch in sorted batch_code order: all of one
-        batch's offerings are placed and locked before the next batch is
-        considered. Treats Phases 1+2 (already marked busy) as fixed.
-        Returns this phase's sessions.
-        """
-        phase_start = len(self.sessions)
-        offerings = [o for o in self.data["offerings"] if not o["course"]["is_general"]]
-
-        for batch in sorted(self.data["batches"], key=lambda b: b["batch_code"]):
-            batch_code = batch["batch_code"]
-            batch_offerings = [o for o in offerings if batch_code in o["batch_codes"]]
-
-            for offering in batch_offerings:
-                course = offering["course"]
-                room_candidates = self._room_candidates(course["lecture_room_id"], self.classrooms)
-                for _ in range(course["lectures_per_week"]):
-                    session = self._place_lecture(offering, room_candidates, DAYS)
-                    if session is None:
-                        print(f"WARNING: could not place a lecture for course {offering['course_id']} section {offering['section_id']} ({offering['batch_codes']})")
-
-        return self.sessions[phase_start:]
+        return phase3_remaining.run(self.board, self.data)
 
     def run(self):
         self.phase_1_general_courses()
         self.phase_2_labs()
         self.phase_3_remaining_courses()
-        return self.sessions
+        return self.board.sessions
 
 
 def build_schedule():

data/dummy/blocks/rooms.csv

@@ -3,8 +3,10 @@ A-101,Room 101,A,classroom,60
 A-102,Room 102,A,classroom,60
 A-103,Room 103,A,classroom,50
 A-201,Room 201,A,classroom,60
+A-202,Room 202,A,classroom,60
 A-L01,Computer Lab 1,A,lab,35
 A-L02,Computer Lab 2,A,lab,35
+A-L03,Computer Lab 3,A,lab,35
 B-101,Room 101 (B),B,classroom,50
 B-102,Room 102 (B),B,classroom,50
 B-L01,Electronics Lab,B,lab,30

data/dummy/courses/course_offering.csv

@@ -2,43 +2,43 @@ course_id,section_id,batch_codes,instructor_code
 CS101,A,25021519,1001
 CS201,A,25021519,1002
 CS301,A,25021519,1003
-CS302,A,25021519,1001
+CS302,A,25021519,1009
 CS101,B,25021520,1001
 CS201,B,25021520,1002
 CS301,B,25021520,1003
-CS302,B,25021520,1001
+CS302,B,25021520,1012
 EE101,A,25031519,1004
 EE201,A,25031519,1005
-EE301,A,25031519,1004
+EE301,A,25031519,1010
 EE101,B,25031520,1004
 EE201,B,25031520,1005
-EE301,B,25031520,1004
+EE301,B,25031520,1010
 BBA101,A,25041519,1007
 BBA201,A,25041519,1008
-BBA301,A,25041519,1007
+BBA301,A,25041519,1011
 BBA101,B,25041520,1007
 BBA201,B,25041520,1008
-BBA301,B,25041520,1007
+BBA301,B,25041520,1011
 CS101,C,26021519,1001
 CS201,C,26021519,1002
 CS301,C,26021519,1003
-CS302,C,26021519,1001
+CS302,C,26021519,1009
 CS101,D,26021520,1001
 CS201,D,26021520,1002
 CS301,D,26021520,1003
-CS302,D,26021520,1001
+CS302,D,26021520,1012
 EE101,C,26031519,1004
 EE201,C,26031519,1005
-EE301,C,26031519,1004
+EE301,C,26031519,1010
 EE101,D,26031520,1004
 EE201,D,26031520,1005
-EE301,D,26031520,1004
+EE301,D,26031520,1010
 BBA101,C,26041519,1007
 BBA201,C,26041519,1008
-BBA301,C,26041519,1007
+BBA301,C,26041519,1011
 BBA101,D,26041520,1007
 BBA201,D,26041520,1008
-BBA301,D,26041520,1007
+BBA301,D,26041520,1011
 GEN101,ALL,25021519|25021520|25031519|25031520|25041519|25041520,1002
 GEN102,ALL,25021519|25021520|25031519|25031520|25041519|25041520,1006
 GEN103,ALL,25021519|25021520|25031519|25031520|25041519|25041520,1006

data/dummy/courses/courses.csv

@@ -1,8 +1,8 @@
 course_id,course_name,credit_hours,lectures_per_week,labs_per_week,is_general,lecture_room_id,lab_room_id,lecture_duration_minutes
 CS101,Programming Fundamentals,4,2,1,no,A-101,A-L01,90
-CS201,Data Structures,4,2,1,no,A-102,A-L01,90
-CS301,Operating Systems,3,1,1,no,A-101,A-L02,120
-CS302,Database Systems,4,2,2,no,A-102,A-L02,90
+CS201,Data Structures,4,2,1,no,A-102,A-L02,90
+CS301,Operating Systems,3,1,1,no,A-101,A-L03,120
+CS302,Database Systems,4,2,1,no,A-102,A-L01,90
 EE101,Basic Electronics,4,2,1,no,A-201,A-L02,90
 EE201,Digital Logic Design,4,2,1,no,B-101,B-L01,90
 EE301,Signals and Systems,3,1,0,no,B-102,,120
@@ -11,4 +11,4 @@ BBA201,Financial Accounting,3,2,0,no,B-102,,90
 BBA301,Marketing Management,3,1,0,no,A-103,,120
 GEN101,Functional English,3,2,0,yes,A-103,,90
 GEN102,Islamic Studies,2,1,0,yes,A-103,,90
-GEN103,Pakistan Studies,2,1,0,yes,B-101,,120
+GEN103,Pakistan Studies,2,1,0,yes,A-202,,120

data/dummy/generate_dummy_data.py

@@ -38,8 +38,9 @@ def main():
         ],
     )
 
-    # ---- rooms: deliberately tight relative to demand (see offerings
-    # below) so room contention is real, spread across both blocks ----
+    # ---- rooms: tight enough to keep real contention, but with enough
+    # total capacity that a correct solver can always find a fit (room
+    # capacity/student-count is not a constraint here) ----
     write_csv(
         "blocks/rooms.csv",
         ["room_id", "room_name", "block_id", "room_type", "capacity"],
@@ -48,8 +49,10 @@ def main():
             ["A-102", "Room 102", "A", "classroom", 60],
             ["A-103", "Room 103", "A", "classroom", 50],
             ["A-201", "Room 201", "A", "classroom", 60],
+            ["A-202", "Room 202", "A", "classroom", 60],
             ["A-L01", "Computer Lab 1", "A", "lab", 35],
             ["A-L02", "Computer Lab 2", "A", "lab", 35],
+            ["A-L03", "Computer Lab 3", "A", "lab", 35],
             ["B-101", "Room 101 (B)", "B", "classroom", 50],
             ["B-102", "Room 102 (B)", "B", "classroom", 50],
             ["B-L01", "Electronics Lab", "B", "lab", 30],
@@ -97,15 +100,18 @@ def main():
     #
     # Mixed lecture durations: most courses are 90-min x N/week, but a few
     # are the special "2 hours once a week" case (lecture_duration_minutes
-    # 120, lectures_per_week 1). Labs vary 0/1/2 per week. Deliberately
-    # more courses per department than the room/instructor pool can
-    # comfortably absorb without contention.
+    # 120, lectures_per_week 1). A course's lab, if it has one, is always
+    # exactly once a week (180 minutes) — never more. Deliberately more
+    # courses per department than the room/instructor pool can comfortably
+    # absorb without contention.
     courses = [
-        # CS department courses
+        # CS department courses — lab rooms spread across A-L01/A-L02/A-L03
+        # so no single lab room is asked for more sessions than exist
+        # weekly slots for it (5 days x 2 lab-slot-pairs = 10/week).
         ["CS101", "Programming Fundamentals", 4, 2, 1, "no", "A-101", "A-L01", 90],
-        ["CS201", "Data Structures", 4, 2, 1, "no", "A-102", "A-L01", 90],
-        ["CS301", "Operating Systems", 3, 1, 1, "no", "A-101", "A-L02", 120],
-        ["CS302", "Database Systems", 4, 2, 2, "no", "A-102", "A-L02", 90],
+        ["CS201", "Data Structures", 4, 2, 1, "no", "A-102", "A-L02", 90],
+        ["CS301", "Operating Systems", 3, 1, 1, "no", "A-101", "A-L03", 120],
+        ["CS302", "Database Systems", 4, 2, 1, "no", "A-102", "A-L01", 90],
         # EE department courses
         ["EE101", "Basic Electronics", 4, 2, 1, "no", "A-201", "A-L02", 90],
         ["EE201", "Digital Logic Design", 4, 2, 1, "no", "B-101", "B-L01", 90],
@@ -117,7 +123,7 @@ def main():
         # General (shared) courses
         ["GEN101", "Functional English", 3, 2, 0, "yes", "A-103", "", 90],
         ["GEN102", "Islamic Studies", 2, 1, 0, "yes", "A-103", "", 90],
-        ["GEN103", "Pakistan Studies", 2, 1, 0, "yes", "B-101", "", 120],
+        ["GEN103", "Pakistan Studies", 2, 1, 0, "yes", "A-202", "", 120],
     ]
     write_csv(
         "courses/courses.csv",
@@ -139,26 +145,46 @@ def main():
         "EE": ["EE101", "EE201", "EE301"],
         "BBA": ["BBA101", "BBA201", "BBA301"],
     }
-    # Small pools relative to (department batches x courses) demand.
+    # One instructor per course within a department (so no instructor ever
+    # teaches two different courses to the same section/batch, which would
+    # double their weekly slot demand against that batch's narrow shared
+    # availability) — still a tight pool overall since each instructor
+    # teaches their course across every section of the department.
     dept_instructors = {
-        "CS": ["1001", "1002", "1003"],
-        "EE": ["1004", "1005"],
-        "BBA": ["1007", "1008"],
+        "CS": ["1001", "1002", "1003", "1009"],
+        "EE": ["1004", "1005", "1010"],
+        "BBA": ["1007", "1008", "1011"],
     }
+    # CS302 additionally alternates between two instructors across its
+    # sections (instead of one instructor owning all 4) since it has the
+    # heaviest per-section load (2 lectures + 2 labs/week) — one person
+    # covering every section of it would need more slot-0 room than a
+    # single instructor realistically has once other batches' commitments
+    # are accounted for.
+    course_instructor_rotation = {"CS302": ["1009", "1012"]}
+    instructor_names_extra = {"1012": "Ms. Rabia Nasir"}
 
     offerings = []
     section_letters = ["A", "B", "C", "D"]
     dept_section_counter = {"CS": 0, "EE": 0, "BBA": 0}
 
     for batch_code, department, program, session in all_batches:
-        section_id = section_letters[dept_section_counter[department] % len(section_letters)]
+        section_index = dept_section_counter[department]
+        section_id = section_letters[section_index % len(section_letters)]
         dept_section_counter[department] += 1
 
         instr_pool = dept_instructors[department]
+        # One instructor per course, consistent across every section, so
+        # no instructor ever teaches two different courses to the same
+        # batch (which would silently double their contested slot-0
+        # demand against that one batch). The pool is still tight overall
+        # since each instructor teaches their course to every section of
+        # the department -> real instructor contention across sections.
         for i, course_id in enumerate(dept_courses[department]):
-            # Deliberately narrow instructor rotation (2-3 instructors
-            # covering 3-4 courses per department) so the same instructor
-            # teaches multiple courses/sections -> instructor contention.
+            if course_id in course_instructor_rotation:
+                rotation = course_instructor_rotation[course_id]
+                instr = rotation[section_index % len(rotation)]
+            else:
                 instr = instr_pool[i % len(instr_pool)]
             offerings.append([course_id, section_id, batch_code, instr])
 
@@ -190,6 +216,10 @@ def main():
         "1006": "Ms. Hira Shah",
         "1007": "Dr. Nadia Farooq",
         "1008": "Mr. Kamran Sheikh",
+        "1009": "Ms. Ayesha Malik",
+        "1010": "Mr. Imran Qureshi",
+        "1011": "Dr. Saima Aziz",
+        **instructor_names_extra,
     }
     instructors = []
     for course_id, section_id, batch_codes, instr_code in offerings:

data/dummy/instructor/instructors.csv

@@ -2,43 +2,43 @@ instructor_code,instructor_name,course_id,section_id
 1001,Dr. Ahsan Raza,CS101,A
 1002,Ms. Sana Tariq,CS201,A
 1003,Mr. Bilal Khan,CS301,A
-1001,Dr. Ahsan Raza,CS302,A
+1009,Ms. Ayesha Malik,CS302,A
 1001,Dr. Ahsan Raza,CS101,B
 1002,Ms. Sana Tariq,CS201,B
 1003,Mr. Bilal Khan,CS301,B
-1001,Dr. Ahsan Raza,CS302,B
+1012,Ms. Rabia Nasir,CS302,B
 1004,Dr. Farah Iqbal,EE101,A
 1005,Mr. Usman Ali,EE201,A
-1004,Dr. Farah Iqbal,EE301,A
+1010,Mr. Imran Qureshi,EE301,A
 1004,Dr. Farah Iqbal,EE101,B
 1005,Mr. Usman Ali,EE201,B
-1004,Dr. Farah Iqbal,EE301,B
+1010,Mr. Imran Qureshi,EE301,B
 1007,Dr. Nadia Farooq,BBA101,A
 1008,Mr. Kamran Sheikh,BBA201,A
-1007,Dr. Nadia Farooq,BBA301,A
+1011,Dr. Saima Aziz,BBA301,A
 1007,Dr. Nadia Farooq,BBA101,B
 1008,Mr. Kamran Sheikh,BBA201,B
-1007,Dr. Nadia Farooq,BBA301,B
+1011,Dr. Saima Aziz,BBA301,B
 1001,Dr. Ahsan Raza,CS101,C
 1002,Ms. Sana Tariq,CS201,C
 1003,Mr. Bilal Khan,CS301,C
-1001,Dr. Ahsan Raza,CS302,C
+1009,Ms. Ayesha Malik,CS302,C
 1001,Dr. Ahsan Raza,CS101,D
 1002,Ms. Sana Tariq,CS201,D
 1003,Mr. Bilal Khan,CS301,D
-1001,Dr. Ahsan Raza,CS302,D
+1012,Ms. Rabia Nasir,CS302,D
 1004,Dr. Farah Iqbal,EE101,C
 1005,Mr. Usman Ali,EE201,C
-1004,Dr. Farah Iqbal,EE301,C
+1010,Mr. Imran Qureshi,EE301,C
 1004,Dr. Farah Iqbal,EE101,D
 1005,Mr. Usman Ali,EE201,D
-1004,Dr. Farah Iqbal,EE301,D
+1010,Mr. Imran Qureshi,EE301,D
 1007,Dr. Nadia Farooq,BBA101,C
 1008,Mr. Kamran Sheikh,BBA201,C
-1007,Dr. Nadia Farooq,BBA301,C
+1011,Dr. Saima Aziz,BBA301,C
 1007,Dr. Nadia Farooq,BBA101,D
 1008,Mr. Kamran Sheikh,BBA201,D
-1007,Dr. Nadia Farooq,BBA301,D
+1011,Dr. Saima Aziz,BBA301,D
 1002,Ms. Sana Tariq,GEN101,ALL
 1006,Ms. Hira Shah,GEN102,ALL
 1006,Ms. Hira Shah,GEN103,ALL

logs/template_generator.log

@@ -1,12 +1,12 @@
-Timetable generation log - started 2026-09-09T18:19:44.655145
+Timetable generation log - started 2026-09-09T18:55:26.141293
 ================================================================================
-[18:19:44] INFO: clear_all: schedule state, result templates, and log have been reset. Run phase_1 to start over.
-[18:19:48] INFO: Phase 1/3: scheduling general courses (Tue/Thu preferred)...
-[18:19:48] INFO: [Phase 1 (general courses)] No conflicts found — clash-free.
-[18:19:48] INFO: phase_1 complete: 8 session(s) added this phase, 8 total so far. State saved to D:\projects\UORM\timetable\result\schedule_state.json.
-[18:19:57] INFO: Phase 2/3: scheduling labs (on top of phase_1's fixed placements)...
-[18:19:57] INFO: [Phase 2 (general courses + labs)] No conflicts found — clash-free.
-[18:19:57] INFO: phase_2 complete: 23 session(s) added this phase, 31 total so far. State saved to D:\projects\UORM\timetable\result\schedule_state.json.
-[18:20:05] INFO: Phase 3/3: scheduling remaining courses (batch by batch)...
-[18:20:05] INFO: [Phase 3 (full schedule)] No conflicts found — clash-free.
-[18:20:05] INFO: phase_3 complete: 51 session(s) added this phase, 82 total so far. State saved to D:\projects\UORM\timetable\result\schedule_state.json.
+[18:55:26] INFO: clear_all: schedule state, result templates, and log have been reset. Run phase_1 to start over.
+[18:55:26] INFO: Phase 1/3: scheduling general courses (Tue/Thu preferred)...
+[18:55:26] INFO: [Phase 1 (general courses)] No conflicts found — clash-free.
+[18:55:26] INFO: phase_1 complete: 8 session(s) added this phase, 8 total so far. State saved to D:\projects\UORM\timetable\result\schedule_state.json.
+[18:55:29] INFO: Phase 2/3: scheduling labs (on top of phase_1's fixed placements)...
+[18:55:29] INFO: [Phase 2 (general courses + labs)] No conflicts found — clash-free.
+[18:55:29] INFO: phase_2 complete: 24 session(s) added this phase, 32 total so far. State saved to D:\projects\UORM\timetable\result\schedule_state.json.
+[18:55:32] INFO: Phase 3/3: scheduling remaining courses (batch by batch)...
+[18:55:32] INFO: [Phase 3 (full schedule)] No conflicts found — clash-free.
+[18:55:33] INFO: phase_3 complete: 68 session(s) added this phase, 100 total so far. State saved to D:\projects\UORM\timetable\result\schedule_state.json.