diff --git a/backend/scripts/merge_duplicate_conditions.py b/backend/scripts/merge_duplicate_conditions.py
new file mode 100644
index 0000000..0f2befc
--- /dev/null
+++ b/backend/scripts/merge_duplicate_conditions.py
@@ -0,0 +1,147 @@
+"""Give each condition one home, and keep its other systems as cross-links.
+
+The tag→category conversion made every question's subject tag a parent, so a
+question tagged both Pulmonology and Emergency Medicine produced an "Asthma" row
+under each. "Asthma" is therefore not one topic with 45 questions but several
+fragments no filter ever adds up — 330 of 618 condition names live in more than
+one system, a few in eight.
+
+Merging keeps the row with the most questions and folds the rest into it. The
+association with the other systems is not thrown away: each moved question gains
+a `question_category_links` row pointing at the system it came from, which is the
+mechanism built for "this matters to nephrology *and* emergency medicine".
+Duplicate rows are the wrong way to say that; a link is the right one.
+
+Only names appearing in several systems are touched, and only when one row is a
+clear plurality — an even split is reported for a human to decide rather than
+broken by an arbitrary rule.
+
+    docker compose exec backend python -m scripts.merge_duplicate_conditions
+    docker compose exec backend python -m scripts.merge_duplicate_conditions --apply
+    docker compose exec backend python -m scripts.merge_duplicate_conditions --min-questions 5
+"""
+import sys
+from collections import defaultdict
+
+from sqlalchemy import text as sa_text
+
+from app.database import SessionLocal
+
+
+def direct_count(db, category_id: int) -> int:
+    return db.execute(sa_text("""
+        SELECT (SELECT COUNT(*) FROM questions WHERE question_category_id = :c)
+             + (SELECT COUNT(*) FROM question_category_links WHERE category_id = :c)
+    """), {"c": category_id}).scalar() or 0
+
+
+def root_of(db, category_id: int) -> int:
+    """The system a row sits under, walking up at most a few levels."""
+    cursor, guard = category_id, 0
+    while guard < 8:
+        parent = db.execute(sa_text(
+            "SELECT parent_id FROM question_categories WHERE id = :c"), {"c": cursor}).scalar()
+        if parent is None:
+            return cursor
+        cursor, guard = parent, guard + 1
+    return cursor
+
+
+def main():
+    apply_changes = "--apply" in sys.argv
+    threshold = 0
+    if "--min-questions" in sys.argv:
+        threshold = int(sys.argv[sys.argv.index("--min-questions") + 1])
+
+    db = SessionLocal()
+    try:
+        rows = db.execute(sa_text("""
+            SELECT c.id, c.name, c.parent_id FROM question_categories c
+            WHERE c.parent_id IS NOT NULL
+        """)).fetchall()
+        names = dict(db.execute(sa_text("SELECT id, name FROM question_categories")).fetchall())
+
+        by_name: dict[str, list] = defaultdict(list)
+        for cid, name, _parent in rows:
+            by_name[name.strip().lower()].append(cid)
+
+        plans, ambiguous = [], []
+        for key, ids in by_name.items():
+            if len(ids) < 2:
+                continue
+            counts = {cid: direct_count(db, cid) for cid in ids}
+            total = sum(counts.values())
+            if total < threshold:
+                continue
+            ranked = sorted(ids, key=lambda cid: (-counts[cid], cid))
+            best, runner_up = counts[ranked[0]], counts[ranked[1]]
+            entry = (names[ranked[0]], ranked[0], ranked[1:], counts, total)
+            # An even split has no evidence-based winner, so leave it to a human.
+            if best == runner_up:
+                ambiguous.append(entry)
+            else:
+                plans.append(entry)
+
+        plans.sort(key=lambda e: -e[4])
+        ambiguous.sort(key=lambda e: -e[4])
+
+        moved_questions = 0
+        if apply_changes:
+            for _name, keeper, losers, _counts, _total in plans:
+                for loser in losers:
+                    system = root_of(db, loser)
+                    # Preserve the association with the system being folded away.
+                    db.execute(sa_text("""
+                        INSERT INTO question_category_links (question_id, category_id)
+                        SELECT q.id, :sys FROM questions q
+                        WHERE q.question_category_id = :loser
+                          AND NOT EXISTS (SELECT 1 FROM question_category_links l
+                                          WHERE l.question_id = q.id AND l.category_id = :sys)
+                    """), {"sys": system, "loser": loser})
+                    db.execute(sa_text(
+                        "UPDATE questions SET question_category_id = :k WHERE question_category_id = :l"),
+                        {"k": keeper, "l": loser})
+                    db.execute(sa_text("""
+                        UPDATE question_category_links SET category_id = :k
+                        WHERE category_id = :l AND question_id NOT IN (
+                            SELECT question_id FROM question_category_links WHERE category_id = :k)
+                    """), {"k": keeper, "l": loser})
+                    db.execute(sa_text("DELETE FROM question_category_links WHERE category_id = :l"),
+                               {"l": loser})
+                    db.execute(sa_text("UPDATE articles SET category_id = :k WHERE category_id = :l"),
+                               {"k": keeper, "l": loser})
+                    db.execute(sa_text("UPDATE flashcard_decks SET category_id = :k WHERE category_id = :l"),
+                               {"k": keeper, "l": loser})
+                    db.execute(sa_text("UPDATE question_categories SET parent_id = :k WHERE parent_id = :l"),
+                               {"k": keeper, "l": loser})
+                    db.execute(sa_text("DELETE FROM category_grants WHERE category_id = :l"), {"l": loser})
+                    db.execute(sa_text("DELETE FROM question_categories WHERE id = :l"), {"l": loser})
+                    moved_questions += 1
+            db.commit()
+
+        print("APPLIED" if apply_changes else "DRY RUN")
+        print(f"  duplicated names   : {len(plans) + len(ambiguous)}")
+        print(f"  merges planned     : {len(plans)}  (rows removed: {sum(len(p[2]) for p in plans)})")
+        print(f"  need a human call  : {len(ambiguous)}\n")
+
+        print("  Largest merges (keeper shown first):")
+        for name, keeper, losers, counts, total in plans[:25]:
+            homes = " + ".join(
+                f"{names.get(root_of(db, cid), '?')}:{counts[cid]}" for cid in [keeper, *losers])
+            print(f"    {name} — {total} questions across {len(losers) + 1} systems  [{homes}]")
+
+        if ambiguous:
+            print("\n  Even splits — pick a home yourself, nothing was merged:")
+            for name, keeper, losers, counts, total in ambiguous[:15]:
+                homes = ", ".join(
+                    f"{names.get(root_of(db, cid), '?')}" for cid in [keeper, *losers])
+                print(f"    {name} — {total} questions, tied across {homes}")
+
+        if not apply_changes:
+            print("\n  Re-run with --apply to merge, or --min-questions N to limit scope.")
+    finally:
+        db.close()
+
+
+if __name__ == "__main__":
+    sys.exit(main())
diff --git a/backend/scripts/nest_systems.py b/backend/scripts/nest_systems.py
new file mode 100644
index 0000000..52da2a1
--- /dev/null
+++ b/backend/scripts/nest_systems.py
@@ -0,0 +1,286 @@
+"""Give the system tree a middle level: System → Subsystem → Condition.
+
+The tree came from the old subject tags, so every condition sits directly under
+its system — 27 roots and about 1,050 leaves, one level deep. That makes the
+Systems picker a flat alphabetical wall.
+
+The subsystem names here are standard textbook divisions, not invented ones, and
+each is matched by an explicit pattern so a dry run shows exactly what will move.
+
+Deliberately conservative in three ways:
+  * a condition that matches no pattern stays directly under its system, rather
+    than being forced into an approximate bucket;
+  * a subsystem that would hold fewer than MIN_CHILDREN is not created, so the
+    tree does not sprout one-item branches;
+  * nothing is reclassified across systems, and nothing is merged. Conditions
+    that look misfiled or synonymous are *reported* for a human to judge, because
+    deciding that "Trisomy 21" and "Down Syndrome" are one thing, or that Marfan
+    belongs under Genetics, is a medical call and not a string comparison.
+
+    docker compose exec backend python -m scripts.nest_systems
+    docker compose exec backend python -m scripts.nest_systems --apply
+"""
+import re
+import sys
+from collections import defaultdict
+
+from sqlalchemy import text as sa_text
+
+from app.database import SessionLocal
+
+MIN_CHILDREN = 2
+
+# system -> [(subsystem, pattern matched against the condition name)]
+SUBSYSTEMS: dict[str, list[tuple[str, str]]] = {
+    "Cardiology": [
+        ("Congenital Heart Disease", r"septal defect|tetralogy|transposition|ductus arteriosus|"
+                                     r"hypoplastic left|bicuspid|coarctation|congenital heart|"
+                                     r"cyanotic heart|truncus|ebstein|pulmonary atresia"),
+        ("Arrhythmias", r"arrhythmi|long qt|wolff|tachycardi|bradycardi|heart block|sudden cardiac"),
+        ("Cardiomyopathy", r"cardiomyopath"),
+        ("Heart Failure", r"heart failure"),
+        ("Inflammatory Heart Disease", r"myocarditis|pericarditis|endocarditis|rheumatic"),
+        ("Vascular", r"hypertension|hyperlipid|hypercholesterol|vasculitis"),
+    ],
+    "Neurology": [
+        ("Seizures & Epilepsy", r"seizure|epilep|status epilepticus|febrile convulsion|infantile spasm"),
+        ("Headache", r"headache|migraine"),
+        ("Neuromuscular", r"muscular dystroph|myopath|neuropath|myasthen|guillain|spinal muscular|hypotoni"),
+        ("Neurocutaneous", r"neurofibromatos|tuberous sclerosis|sturge|von hippel"),
+        ("CNS Infection", r"meningitis|encephalitis|brain abscess"),
+        ("Movement Disorders", r"ataxia|chorea|dystonia|tic disorder|tourette"),
+        ("Developmental Brain Disorders", r"cerebral palsy|hydrocephal|spina bifida|neural tube|"
+                                          r"microcephal|macrocephal|craniosynostos"),
+    ],
+    "Infectious Disease": [
+        ("Bacterial Infections", r"bacter|strep|staph|pertussis|tuberculosis|lyme|salmonell|"
+                                 r"shigell|cellulitis|impetigo|osteomyelitis|scarlet"),
+        ("Viral Infections", r"viral|virus|measles|mumps|rubella|varicella|influenza|herpes|"
+                             r"hepatitis|hiv|mononucleosis|roseola|hand foot|croup|rsv"),
+        ("Parasitic & Fungal", r"parasit|malaria|giardia|pinworm|helminth|fungal|candid|tinea|scabies|lice"),
+        ("Immunisation & Prophylaxis", r"vaccin|immuniz|immunis|prophylax"),
+        ("Congenital Infections", r"congenital infection|toxoplasm|cytomegalovirus|congenital syphilis"),
+    ],
+    "Neonatology": [
+        ("Neonatal Jaundice", r"jaundice|bilirubin|kernicterus"),
+        ("Neonatal Respiratory", r"respiratory distress|surfactant|meconium aspiration|apnea|bronchopulmonary|"
+                                 r"transient tachypnea|pneumothorax"),
+        ("Prematurity", r"prematur|preterm|low birth weight|intraventricular h|retinopathy of prematurity|"
+                        r"necrotizing enterocolitis"),
+        ("Neonatal Infection", r"neonatal sepsis|early onset sepsis|late onset sepsis|group b strep"),
+        ("Birth Injury & Asphyxia", r"birth injur|asphyxia|hypoxic ischemic|brachial plexus|cephalohematoma|"
+                                    r"caput"),
+        ("Newborn Screening", r"newborn screen|metabolic screen"),
+    ],
+    "Pulmonology": [
+        ("Asthma & Wheezing", r"asthma|wheez|reactive airway"),
+        ("Lower Airway Infection", r"bronchiolitis|pneumonia|bronchitis"),
+        ("Upper Airway", r"croup|epiglottitis|tracheitis|stridor|laryngomalacia|obstructive sleep"),
+        ("Cystic Fibrosis", r"cystic fibrosis"),
+        ("Foreign Body & Aspiration", r"foreign body|aspiration pneumon"),
+    ],
+    "Gastroenterology & Nutrition": [
+        ("Diarrhoea & Gastroenteritis", r"diarrhea|diarrhoea|gastroenteritis|dehydration"),
+        ("Constipation & Motility", r"constipation|hirschsprung|encopresis|motility"),
+        ("Liver Disease", r"hepat|liver|biliary|cirrhosis"),
+        ("Malabsorption", r"celiac|malabsorption|lactose|short bowel"),
+        ("Inflammatory Bowel Disease", r"crohn|ulcerative colitis|inflammatory bowel"),
+        ("Surgical Abdomen", r"appendicitis|intussusception|volvulus|pyloric stenosis|obstruction|"
+                             r"malrotation|acute abdomen"),
+        ("Nutrition & Growth", r"nutrition|failure to thrive|obesity|vitamin|malnutrition|rickets|"
+                               r"breastfeed|deficiency"),
+        ("Reflux & Peptic Disease", r"reflux|gerd|peptic|gastritis|ulcer"),
+    ],
+    "Endocrinology": [
+        ("Diabetes", r"diabet|ketoacidosis|hypoglycem|insulin"),
+        ("Thyroid", r"thyroid|hypothyroid|hyperthyroid|goiter"),
+        ("Growth Disorders", r"short stature|growth hormone|tall stature|growth failure"),
+        ("Puberty", r"puberty|precocious|delayed puberty|gynecomastia"),
+        ("Adrenal", r"adrenal|cushing|addison|congenital adrenal"),
+        ("Calcium & Bone", r"calcium|rickets|parathyroid|vitamin d"),
+    ],
+    "Hematology-Oncology": [
+        ("Anaemia", r"anemia|anaemia|thalassem|sickle|spherocytos|g6pd|iron deficiency"),
+        ("Bleeding & Clotting", r"hemophil|thrombocytopen|coagulop|von willebrand|purpura|thrombo"),
+        ("Leukaemia & Lymphoma", r"leukemi|leukaemi|lymphoma|hodgkin"),
+        ("Solid Tumours", r"neuroblastoma|wilms|sarcoma|retinoblastoma|brain tumor|tumour|osteosarcoma"),
+    ],
+    "Nephrology & Urology": [
+        ("Urinary Tract Infection", r"urinary tract infection|pyelonephritis|cystitis|uti"),
+        ("Glomerular Disease", r"glomerulonephritis|nephrotic|nephritic|proteinuria|hematuria|iga"),
+        ("Acute & Chronic Kidney Disease", r"kidney injury|renal failure|kidney disease|renal insufficiency"),
+        ("Congenital Urinary Tract", r"vesicoureteral|hydronephrosis|posterior urethral|reflux nephropathy"),
+        ("Electrolytes & Acid-Base", r"hyponatrem|hypernatrem|hypokalem|hyperkalem|acidosis|alkalosis|electrolyte"),
+        ("Genital & Scrotal", r"testicular torsion|hydrocele|cryptorchid|phimosis|hypospadias|scrotal"),
+    ],
+    "Dermatology": [
+        ("Eczema & Dermatitis", r"eczema|dermatitis|atopic"),
+        ("Skin Infections", r"impetigo|cellulitis|tinea|scabies|warts|molluscum|abscess"),
+        ("Rashes & Exanthems", r"exanthem|\brash\b|urticaria|\berythema\b"),
+        ("Birthmarks & Vascular Lesions", r"hemangioma|nevus|port wine|birthmark"),
+        ("Acne", r"acne"),
+    ],
+    "Allergy/Immunology": [
+        ("Food Allergy", r"food allerg|anaphylax|peanut|milk protein"),
+        ("Allergic Rhinitis & Atopy", r"allergic rhinitis|atopy|hay fever"),
+        ("Immunodeficiency", r"immunodefic|scid|agammaglobulin|chronic granulomatous|complement deficiency"),
+        ("Drug Allergy", r"drug allerg|drug reaction|penicillin allerg"),
+    ],
+    "Orthopedics & Sports": [
+        ("Fractures & Trauma", r"fracture|dislocation|sprain|trauma|injury"),
+        ("Hip Disorders", r"hip dysplasia|slipped capital|legg|perthes|developmental dysplasia"),
+        ("Spine", r"scoliosis|kyphosis|spondylolisthesis|back pain"),
+        ("Bone & Joint Infection", r"osteomyelitis|septic arthritis"),
+        ("Limb & Gait", r"limp|gait|bowleg|genu|clubfoot|torsion"),
+    ],
+    "Psychiatry & Psychology": [
+        ("Mood Disorders", r"depress|bipolar|mood"),
+        ("Anxiety Disorders", r"anxiety|panic|phobia|obsessive"),
+        ("Neurodevelopmental", r"adhd|attention deficit|autism|learning disab|intellectual disab"),
+        ("Behaviour Disorders", r"conduct disorder|oppositional|impulse|aggression"),
+        ("Eating Disorders", r"anorexia|bulimia|eating disorder"),
+        ("Trauma & Stress", r"ptsd|trauma|stress disorder|adjustment disorder"),
+    ],
+    "Emergency Medicine": [
+        ("Shock & Resuscitation", r"shock|resuscitat|cardiac arrest|cpr"),
+        ("Trauma", r"trauma|fracture|burn|head injury|drowning"),
+        ("Poisoning", r"poison|overdose|ingestion|toxic"),
+        ("Respiratory Emergencies", r"respiratory failure|respiratory distress|airway|anaphylax"),
+        ("Altered Consciousness & Seizure", r"seizure|status epilepticus|altered mental|coma|syncope"),
+    ],
+    "Genetics & Metabolism": [
+        ("Chromosomal Disorders", r"trisomy|down syndrome|turner|klinefelter|deletion syndrome|"
+                                  r"chromosom|22q11"),
+        ("Inborn Errors of Metabolism", r"phenylketonuria|galactosem|urea cycle|mitochondrial|"
+                                        r"glycogen storage|lysosomal|metabolic disorder|maple syrup"),
+        ("Connective Tissue Disorders", r"marfan|ehlers|osteogenesis imperfecta|connective tissue"),
+        ("Skeletal Dysplasias", r"achondroplasia|dysplasia|dwarfism"),
+    ],
+    "Adolescent Medicine": [
+        ("Sexual & Reproductive Health", r"sexually transmitted|contracept|pregnan|menstrua|"
+                                         r"dysmenorrh|amenorrh|uterine bleeding"),
+        ("Substance Use", r"substance|alcohol|smoking|vaping|drug use|marijuana|opioid"),
+        ("Mental Health", r"depress|suicid|self harm|anxiety|eating disorder"),
+        ("Growth & Puberty", r"puberty|acne|gynecomastia|scoliosis"),
+    ],
+}
+
+
+
+def report_misfiled(db) -> None:
+    """List conditions that match another system's patterns better than their own.
+
+    Reported, never moved: deciding that Down Syndrome belongs under Genetics
+    rather than Cardiology is a medical call, and a pattern match is only a hint.
+    """
+    roots = db.execute(sa_text(
+        "SELECT id, name FROM question_categories WHERE parent_id IS NULL")).fetchall()
+    root_name = {row[0]: row[1] for row in roots}
+    compiled = {system: [(sub, re.compile(pattern, re.I)) for sub, pattern in rules]
+                for system, rules in SUBSYSTEMS.items()}
+
+    rows = db.execute(sa_text("""
+        SELECT c.id, c.name, r.id
+        FROM question_categories c
+        JOIN question_categories r ON r.id = c.parent_id
+        WHERE r.parent_id IS NULL
+        ORDER BY c.name
+    """)).fetchall()
+
+    suspects = []
+    for _cid, name, parent_id in rows:
+        home = root_name.get(parent_id)
+        if home in compiled and any(p.search(name) for _s, p in compiled[home]):
+            continue  # it fits where it already is
+        elsewhere = [system for system, rules in compiled.items()
+                     if system != home and any(p.search(name) for _s, p in rules)]
+        if elsewhere:
+            suspects.append((name, home, elsewhere))
+
+    print(f"\n  Possibly misfiled ({len(suspects)}) — review, nothing was moved:")
+    for name, home, elsewhere in suspects[:40]:
+        print(f"    {name!r} is under {home} but matches {', '.join(elsewhere)}")
+    if len(suspects) > 40:
+        print(f"    … and {len(suspects) - 40} more")
+
+
+def main():
+    apply_changes = "--apply" in sys.argv
+    db = SessionLocal()
+    try:
+        roots = db.execute(sa_text(
+            "SELECT id, name FROM question_categories WHERE parent_id IS NULL ORDER BY name")).fetchall()
+        by_name = {row[1]: row[0] for row in roots}
+
+        planned: dict[str, list[tuple[str, int, str]]] = defaultdict(list)
+        untouched: dict[str, int] = {}
+
+        for system, rules in SUBSYSTEMS.items():
+            root_id = by_name.get(system)
+            if root_id is None:
+                print(f"  system {system!r} not found; skipping")
+                continue
+            children = db.execute(sa_text("""
+                SELECT id, name FROM question_categories
+                WHERE parent_id = :p ORDER BY name
+            """), {"p": root_id}).fetchall()
+            existing_subs = {name for _cid, name in children if name in {s for s, _ in rules}}
+
+            claimed = set()
+            for subsystem, pattern in rules:
+                matcher = re.compile(pattern, re.I)
+                hits = [(cid, name) for cid, name in children
+                        if cid not in claimed and name not in existing_subs and matcher.search(name)]
+                if len(hits) < MIN_CHILDREN:
+                    continue  # not worth a branch of its own
+                for cid, name in hits:
+                    claimed.add(cid)
+                    planned[system].append((subsystem, cid, name))
+            untouched[system] = len([c for c, _ in children if c not in claimed])
+
+        if apply_changes:
+            for system, moves in planned.items():
+                root_id = by_name[system]
+                sub_ids: dict[str, int] = {}
+                for subsystem, cid, _name in moves:
+                    if subsystem not in sub_ids:
+                        found = db.execute(sa_text("""
+                            SELECT id FROM question_categories
+                            WHERE parent_id = :p AND lower(name) = lower(:n)
+                        """), {"p": root_id, "n": subsystem}).first()
+                        if found:
+                            sub_ids[subsystem] = found[0]
+                        else:
+                            sub_ids[subsystem] = db.execute(sa_text("""
+                                INSERT INTO question_categories (name, parent_id, user_id, created_at)
+                                VALUES (:n, :p, (SELECT id FROM users ORDER BY id LIMIT 1), NOW())
+                                RETURNING id
+                            """), {"n": subsystem, "p": root_id}).scalar()
+                    db.execute(sa_text("UPDATE question_categories SET parent_id = :s WHERE id = :c"),
+                               {"s": sub_ids[subsystem], "c": cid})
+            db.commit()
+
+        print("APPLIED" if apply_changes else "DRY RUN")
+        total_moved = sum(len(v) for v in planned.values())
+        total_subs = sum(len({s for s, _, _ in v}) for v in planned.values())
+        print(f"  subsystems created : {total_subs}")
+        print(f"  conditions nested  : {total_moved}")
+        print(f"  left at top level  : {sum(untouched.values())}\n")
+        for system in sorted(planned):
+            groups: dict[str, list[str]] = defaultdict(list)
+            for subsystem, _cid, name in planned[system]:
+                groups[subsystem].append(name)
+            print(f"  {system}  (+{untouched.get(system, 0)} stay directly under it)")
+            for subsystem, names in sorted(groups.items()):
+                shown = ", ".join(names[:4])
+                more = f" … +{len(names) - 4}" if len(names) > 4 else ""
+                print(f"    {subsystem} ({len(names)}): {shown}{more}")
+        report_misfiled(db)
+        if not apply_changes:
+            print("\n  Re-run with --apply to write this structure.")
+    finally:
+        db.close()
+
+
+if __name__ == "__main__":
+    sys.exit(main())
diff --git a/docs/TODO.md b/docs/TODO.md
index e603d06..bf122ae 100644
--- a/docs/TODO.md
+++ b/docs/TODO.md
@@ -83,8 +83,20 @@ Updated 2026-09-10.
 
 ## Taxonomy
 
-- [ ] **Systems need subsystems** — the current tree came from the old subject
-      tags and is flat where it should nest. Disciplines are fine.
+- [x] **Systems subsystems** — done 2026-09-10. 69 subsystems created, 305
+      conditions nested; the tree is now System → Subsystem → Condition.
+- [x] **Cross-system duplicate conditions merged** — done 2026-09-10. 216 names
+      folded to one home each (347 rows removed, 1075 → 786), keeping the other
+      systems as `question_category_links` rather than duplicate rows.
+- [ ] **114 tied conditions need a human call** — an even split across systems
+      has no evidence-based winner, so nothing was merged. Run
+      `scripts/merge_duplicate_conditions.py` to list them; the largest are
+      Pneumonia, Behavioral Disorder, Intestinal Obstruction, Acute Rheumatic
+      Fever, Hypoxic-Ischemic Encephalopathy.
+- [ ] **Most questions are filed at system level** — 2,730 of 2,948 point their
+      primary category at a top-level system rather than a condition, so the
+      condition tree is reached almost entirely through cross-links. Worth
+      deciding whether primary categories should be pushed down the tree.
 - [x] **Grant dimensions** — done 2026-09-10. A grant names any combination of
       exam, discipline and category, and covers what matches all of them.
 - [x] **Exam-scoped disciplines** — done 2026-09-10. A tag may be shared