diff --git a/messages/de.json b/messages/de.json
index 0509f4a9d..9a9480e87 100644
--- a/messages/de.json
+++ b/messages/de.json
@@ -4122,6 +4122,21 @@
           "title": "Benachrichtigungskanäle",
           "description": "APNs, Telegram, ntfy, Web Push, Webhook und E-Mail."
         }
+      },
+      "modules": {
+        "title": "Module",
+        "saved": "Gespeichert.",
+        "error": "Konnte nicht gespeichert werden. Bitte erneut versuchen.",
+        "toggleable": {
+          "title": "Was du trackst",
+          "description": "Optionale Bereiche. Deaktivierte Module verschwinden aus Navigation, Kacheln und Auswertungen — deine Daten bleiben erhalten."
+        },
+        "core": {
+          "title": "Immer aktiv",
+          "description": "Die Grundlagen von HealthLog. Diese Bereiche lassen sich nicht abschalten.",
+          "note": "Kernbereich — immer aktiv"
+        },
+        "description": "Lege fest, was HealthLog für dich erfasst. Schalte einzelne Bereiche ein oder aus — die Navigation, Kacheln und Auswertungen passen sich sofort an."
       }
     },
     "profile": "Profil",
@@ -6511,5 +6526,67 @@
       "savedToast": "Wert gespeichert",
       "saveError": "Wert konnte nicht gespeichert werden"
     }
+  },
+  "modules": {
+    "cycle": {
+      "label": "Zyklus",
+      "description": "Periode, Phasen und Vorhersagen verfolgen."
+    },
+    "mood": {
+      "label": "Stimmung",
+      "description": "Tägliche Stimmung und Tags erfassen."
+    },
+    "sleep": {
+      "label": "Schlaf",
+      "description": "Schlafdauer, Phasen und Schlaf-Timeline."
+    },
+    "glucose": {
+      "label": "Glukose",
+      "description": "Blutzuckerwerte und Verläufe."
+    },
+    "workouts": {
+      "label": "Workouts",
+      "description": "Trainingseinheiten und Aktivität."
+    },
+    "recovery": {
+      "label": "Erholung",
+      "description": "Erholungs- und Belastungswerte deiner Geräte."
+    },
+    "labs": {
+      "label": "Laborwerte",
+      "description": "Laborergebnisse erfassen und im Verlauf ablegen."
+    },
+    "achievements": {
+      "label": "Erfolge",
+      "description": "Abzeichen und Serien für deine Routine."
+    },
+    "coach": {
+      "label": "Coach",
+      "description": "KI-Chat mit Bezug zu deinen Daten."
+    },
+    "insights": {
+      "label": "Auswertungen",
+      "description": "KI-Analysen, Briefing und Korrelationen."
+    },
+    "doctorReport": {
+      "label": "Arztbericht",
+      "description": "PDF- und FHIR-Export für deine Praxis."
+    },
+    "weight": {
+      "label": "Gewicht",
+      "description": "Gewicht und Körperzusammensetzung."
+    },
+    "bloodPressure": {
+      "label": "Blutdruck",
+      "description": "Systolisch und diastolisch."
+    },
+    "pulse": {
+      "label": "Puls",
+      "description": "Ruhepuls und Herzfrequenz."
+    },
+    "medications": {
+      "label": "Medikamente",
+      "description": "Pläne, Einnahmen und Compliance."
+    }
   }
 }
diff --git a/messages/en.json b/messages/en.json
index bbeb6b05a..9c94551de 100644
--- a/messages/en.json
+++ b/messages/en.json
@@ -4122,6 +4122,21 @@
           "title": "Notification channels",
           "description": "APNs, Telegram, ntfy, Web Push, Webhook, and Email."
         }
+      },
+      "modules": {
+        "title": "Modules",
+        "saved": "Saved.",
+        "error": "Couldn't save. Please try again.",
+        "toggleable": {
+          "title": "What you track",
+          "description": "Optional areas. Disabled modules drop out of the navigation, tiles, and insights — your data stays untouched."
+        },
+        "core": {
+          "title": "Always on",
+          "description": "HealthLog's foundations. These areas can't be turned off.",
+          "note": "Core area — always on"
+        },
+        "description": "Choose what HealthLog tracks for you. Turn individual areas on or off — the navigation, tiles, and insights adapt right away."
       }
     },
     "profile": "Profile",
@@ -6511,5 +6526,67 @@
       "savedToast": "Result saved",
       "saveError": "Could not save the result"
     }
+  },
+  "modules": {
+    "cycle": {
+      "label": "Cycle",
+      "description": "Track period, phases, and predictions."
+    },
+    "mood": {
+      "label": "Mood",
+      "description": "Log daily mood and tags."
+    },
+    "sleep": {
+      "label": "Sleep",
+      "description": "Sleep duration, stages, and timeline."
+    },
+    "glucose": {
+      "label": "Glucose",
+      "description": "Blood-glucose readings and trends."
+    },
+    "workouts": {
+      "label": "Workouts",
+      "description": "Training sessions and activity."
+    },
+    "recovery": {
+      "label": "Recovery",
+      "description": "Recovery and strain metrics from your devices."
+    },
+    "labs": {
+      "label": "Lab results",
+      "description": "Capture lab results and keep their history."
+    },
+    "achievements": {
+      "label": "Achievements",
+      "description": "Badges and streaks for your routine."
+    },
+    "coach": {
+      "label": "Coach",
+      "description": "AI chat grounded in your own data."
+    },
+    "insights": {
+      "label": "Insights",
+      "description": "AI analysis, briefing, and correlations."
+    },
+    "doctorReport": {
+      "label": "Doctor report",
+      "description": "PDF and FHIR export for your practice."
+    },
+    "weight": {
+      "label": "Weight",
+      "description": "Weight and body composition."
+    },
+    "bloodPressure": {
+      "label": "Blood pressure",
+      "description": "Systolic and diastolic."
+    },
+    "pulse": {
+      "label": "Pulse",
+      "description": "Resting pulse and heart rate."
+    },
+    "medications": {
+      "label": "Medications",
+      "description": "Schedules, intakes, and compliance."
+    }
   }
 }
diff --git a/messages/es.json b/messages/es.json
index 1eed54b4c..8af901931 100644
--- a/messages/es.json
+++ b/messages/es.json
@@ -4122,6 +4122,21 @@
           "title": "Canales de notificación",
           "description": "APNs, Telegram, ntfy, Web Push, Webhook y correo."
         }
+      },
+      "modules": {
+        "title": "Módulos",
+        "saved": "Guardado.",
+        "error": "No se pudo guardar. Inténtalo de nuevo.",
+        "toggleable": {
+          "title": "Qué registras",
+          "description": "Áreas opcionales. Los módulos desactivados desaparecen de la navegación, los paneles y los análisis; tus datos se conservan."
+        },
+        "core": {
+          "title": "Siempre activos",
+          "description": "Los pilares de HealthLog. Estas áreas no se pueden desactivar.",
+          "note": "Área esencial — siempre activa"
+        },
+        "description": "Elige qué registra HealthLog por ti. Activa o desactiva áreas concretas: la navegación, los paneles y los análisis se adaptan al instante."
       }
     },
     "profile": "Perfil",
@@ -6511,5 +6526,67 @@
       "savedToast": "Resultado guardado",
       "saveError": "No se pudo guardar el resultado"
     }
+  },
+  "modules": {
+    "cycle": {
+      "label": "Ciclo",
+      "description": "Registra periodo, fases y predicciones."
+    },
+    "mood": {
+      "label": "Estado de ánimo",
+      "description": "Registra el ánimo diario y etiquetas."
+    },
+    "sleep": {
+      "label": "Sueño",
+      "description": "Duración, fases y cronología del sueño."
+    },
+    "glucose": {
+      "label": "Glucosa",
+      "description": "Lecturas de glucosa y tendencias."
+    },
+    "workouts": {
+      "label": "Entrenamientos",
+      "description": "Sesiones de entrenamiento y actividad."
+    },
+    "recovery": {
+      "label": "Recuperación",
+      "description": "Métricas de recuperación y carga de tus dispositivos."
+    },
+    "labs": {
+      "label": "Resultados de laboratorio",
+      "description": "Registra resultados de laboratorio y su historial."
+    },
+    "achievements": {
+      "label": "Logros",
+      "description": "Insignias y rachas para tu rutina."
+    },
+    "coach": {
+      "label": "Coach",
+      "description": "Chat de IA basado en tus propios datos."
+    },
+    "insights": {
+      "label": "Análisis",
+      "description": "Análisis de IA, resumen y correlaciones."
+    },
+    "doctorReport": {
+      "label": "Informe médico",
+      "description": "Exportación PDF y FHIR para tu consulta."
+    },
+    "weight": {
+      "label": "Peso",
+      "description": "Peso y composición corporal."
+    },
+    "bloodPressure": {
+      "label": "Presión arterial",
+      "description": "Sistólica y diastólica."
+    },
+    "pulse": {
+      "label": "Pulso",
+      "description": "Pulso en reposo y frecuencia cardiaca."
+    },
+    "medications": {
+      "label": "Medicamentos",
+      "description": "Pautas, tomas y cumplimiento."
+    }
   }
 }
diff --git a/messages/fr.json b/messages/fr.json
index c3a2a9dcc..84d6d1c1e 100644
--- a/messages/fr.json
+++ b/messages/fr.json
@@ -4122,6 +4122,21 @@
           "title": "Canaux de notification",
           "description": "APNs, Telegram, ntfy, Web Push, Webhook et e-mail."
         }
+      },
+      "modules": {
+        "title": "Modules",
+        "saved": "Enregistré.",
+        "error": "Échec de l'enregistrement. Veuillez réessayer.",
+        "toggleable": {
+          "title": "Ce que vous suivez",
+          "description": "Domaines optionnels. Les modules désactivés disparaissent de la navigation, des tuiles et des analyses ; vos données sont conservées."
+        },
+        "core": {
+          "title": "Toujours actifs",
+          "description": "Les fondations de HealthLog. Ces domaines ne peuvent pas être désactivés.",
+          "note": "Domaine essentiel — toujours actif"
+        },
+        "description": "Choisissez ce que HealthLog suit pour vous. Activez ou désactivez chaque domaine : la navigation, les tuiles et les analyses s'adaptent aussitôt."
       }
     },
     "profile": "Profil",
@@ -6511,5 +6526,67 @@
       "savedToast": "Résultat enregistré",
       "saveError": "Impossible d'enregistrer le résultat"
     }
+  },
+  "modules": {
+    "cycle": {
+      "label": "Cycle",
+      "description": "Suivez règles, phases et prévisions."
+    },
+    "mood": {
+      "label": "Humeur",
+      "description": "Notez l'humeur quotidienne et les tags."
+    },
+    "sleep": {
+      "label": "Sommeil",
+      "description": "Durée, phases et chronologie du sommeil."
+    },
+    "glucose": {
+      "label": "Glycémie",
+      "description": "Mesures de glycémie et tendances."
+    },
+    "workouts": {
+      "label": "Entraînements",
+      "description": "Séances d'entraînement et activité."
+    },
+    "recovery": {
+      "label": "Récupération",
+      "description": "Indicateurs de récupération et de charge de vos appareils."
+    },
+    "labs": {
+      "label": "Résultats de labo",
+      "description": "Enregistrez les résultats de laboratoire et leur historique."
+    },
+    "achievements": {
+      "label": "Réussites",
+      "description": "Badges et séries pour votre routine."
+    },
+    "coach": {
+      "label": "Coach",
+      "description": "Chat IA fondé sur vos propres données."
+    },
+    "insights": {
+      "label": "Analyses",
+      "description": "Analyses IA, briefing et corrélations."
+    },
+    "doctorReport": {
+      "label": "Rapport médical",
+      "description": "Export PDF et FHIR pour votre cabinet."
+    },
+    "weight": {
+      "label": "Poids",
+      "description": "Poids et composition corporelle."
+    },
+    "bloodPressure": {
+      "label": "Tension artérielle",
+      "description": "Systolique et diastolique."
+    },
+    "pulse": {
+      "label": "Pouls",
+      "description": "Pouls au repos et fréquence cardiaque."
+    },
+    "medications": {
+      "label": "Médicaments",
+      "description": "Schémas, prises et observance."
+    }
   }
 }
diff --git a/messages/it.json b/messages/it.json
index 2afb522b8..91514bbbb 100644
--- a/messages/it.json
+++ b/messages/it.json
@@ -4122,6 +4122,21 @@
           "title": "Canali di notifica",
           "description": "APNs, Telegram, ntfy, Web Push, Webhook ed e-mail."
         }
+      },
+      "modules": {
+        "title": "Moduli",
+        "saved": "Salvato.",
+        "error": "Salvataggio non riuscito. Riprova.",
+        "toggleable": {
+          "title": "Cosa monitori",
+          "description": "Ambiti opzionali. I moduli disattivati spariscono da navigazione, riquadri e analisi; i tuoi dati restano intatti."
+        },
+        "core": {
+          "title": "Sempre attivi",
+          "description": "Le fondamenta di HealthLog. Questi ambiti non possono essere disattivati.",
+          "note": "Ambito di base — sempre attivo"
+        },
+        "description": "Scegli cosa registra HealthLog per te. Attiva o disattiva i singoli ambiti: navigazione, riquadri e analisi si adattano subito."
       }
     },
     "profile": "Profilo",
@@ -6511,5 +6526,67 @@
       "savedToast": "Risultato salvato",
       "saveError": "Impossibile salvare il risultato"
     }
+  },
+  "modules": {
+    "cycle": {
+      "label": "Ciclo",
+      "description": "Monitora mestruazioni, fasi e previsioni."
+    },
+    "mood": {
+      "label": "Umore",
+      "description": "Registra umore quotidiano ed etichette."
+    },
+    "sleep": {
+      "label": "Sonno",
+      "description": "Durata, fasi e cronologia del sonno."
+    },
+    "glucose": {
+      "label": "Glicemia",
+      "description": "Valori della glicemia e andamenti."
+    },
+    "workouts": {
+      "label": "Allenamenti",
+      "description": "Sessioni di allenamento e attività."
+    },
+    "recovery": {
+      "label": "Recupero",
+      "description": "Metriche di recupero e carico dai tuoi dispositivi."
+    },
+    "labs": {
+      "label": "Esami di laboratorio",
+      "description": "Registra i referti di laboratorio e il loro storico."
+    },
+    "achievements": {
+      "label": "Traguardi",
+      "description": "Badge e serie per la tua routine."
+    },
+    "coach": {
+      "label": "Coach",
+      "description": "Chat IA basata sui tuoi dati."
+    },
+    "insights": {
+      "label": "Analisi",
+      "description": "Analisi IA, briefing e correlazioni."
+    },
+    "doctorReport": {
+      "label": "Referto medico",
+      "description": "Esportazione PDF e FHIR per il tuo studio."
+    },
+    "weight": {
+      "label": "Peso",
+      "description": "Peso e composizione corporea."
+    },
+    "bloodPressure": {
+      "label": "Pressione",
+      "description": "Sistolica e diastolica."
+    },
+    "pulse": {
+      "label": "Battito",
+      "description": "Battito a riposo e frequenza cardiaca."
+    },
+    "medications": {
+      "label": "Farmaci",
+      "description": "Schemi, assunzioni e aderenza."
+    }
   }
 }
diff --git a/messages/pl.json b/messages/pl.json
index a14120194..68cfd262f 100644
--- a/messages/pl.json
+++ b/messages/pl.json
@@ -4122,6 +4122,21 @@
           "title": "Kanały powiadomień",
           "description": "APNs, Telegram, ntfy, Web Push, Webhook i e-mail."
         }
+      },
+      "modules": {
+        "title": "Moduły",
+        "saved": "Zapisano.",
+        "error": "Nie udało się zapisać. Spróbuj ponownie.",
+        "toggleable": {
+          "title": "Co śledzisz",
+          "description": "Obszary opcjonalne. Wyłączone moduły znikają z nawigacji, kafelków i analiz — Twoje dane pozostają nienaruszone."
+        },
+        "core": {
+          "title": "Zawsze aktywne",
+          "description": "Podstawy HealthLog. Tych obszarów nie można wyłączyć.",
+          "note": "Obszar podstawowy — zawsze aktywny"
+        },
+        "description": "Wybierz, co HealthLog ma dla Ciebie śledzić. Włączaj i wyłączaj poszczególne obszary — nawigacja, kafelki i analizy dostosują się od razu."
       }
     },
     "profile": "Profil",
@@ -6511,5 +6526,67 @@
       "savedToast": "Wynik zapisany",
       "saveError": "Nie udało się zapisać wyniku"
     }
+  },
+  "modules": {
+    "cycle": {
+      "label": "Cykl",
+      "description": "Śledź miesiączkę, fazy i prognozy."
+    },
+    "mood": {
+      "label": "Nastrój",
+      "description": "Zapisuj codzienny nastrój i tagi."
+    },
+    "sleep": {
+      "label": "Sen",
+      "description": "Długość, fazy i oś czasu snu."
+    },
+    "glucose": {
+      "label": "Glukoza",
+      "description": "Odczyty glukozy i trendy."
+    },
+    "workouts": {
+      "label": "Treningi",
+      "description": "Sesje treningowe i aktywność."
+    },
+    "recovery": {
+      "label": "Regeneracja",
+      "description": "Wskaźniki regeneracji i obciążenia z Twoich urządzeń."
+    },
+    "labs": {
+      "label": "Wyniki badań",
+      "description": "Zapisuj wyniki badań laboratoryjnych i ich historię."
+    },
+    "achievements": {
+      "label": "Osiągnięcia",
+      "description": "Odznaki i serie dla Twojej rutyny."
+    },
+    "coach": {
+      "label": "Coach",
+      "description": "Czat AI oparty na Twoich danych."
+    },
+    "insights": {
+      "label": "Analizy",
+      "description": "Analizy AI, briefing i korelacje."
+    },
+    "doctorReport": {
+      "label": "Raport dla lekarza",
+      "description": "Eksport PDF i FHIR dla Twojej przychodni."
+    },
+    "weight": {
+      "label": "Waga",
+      "description": "Waga i skład ciała."
+    },
+    "bloodPressure": {
+      "label": "Ciśnienie krwi",
+      "description": "Skurczowe i rozkurczowe."
+    },
+    "pulse": {
+      "label": "Tętno",
+      "description": "Tętno spoczynkowe i rytm serca."
+    },
+    "medications": {
+      "label": "Leki",
+      "description": "Schematy, przyjęcia i zgodność."
+    }
   }
 }
diff --git a/src/app/settings/[section]/page.tsx b/src/app/settings/[section]/page.tsx
index ceee2abed..645e28a1a 100644
--- a/src/app/settings/[section]/page.tsx
+++ b/src/app/settings/[section]/page.tsx
@@ -12,6 +12,7 @@ import { InsightsSection } from "@/components/settings/insights-section";
 import { IntegrationsSection } from "@/components/settings/integrations-section";
 import { LayoutSection } from "@/components/settings/layout-section";
 import { MedicationsSection } from "@/components/settings/medications-section";
+import { ModulesSection } from "@/components/settings/modules-section";
 import { MoodSection } from "@/components/settings/mood-section";
 import { NotificationsSection } from "@/components/settings/notifications-section";
 import { RemindersSection } from "@/components/settings/reminders-section";
@@ -51,6 +52,7 @@ const SECTION_COMPONENTS: Record<
   () => JSX.Element | null
 > = {
   account: AccountSection,
+  modules: ModulesSection,
   about: AboutSection,
   ai: AiSection,
   integrations: IntegrationsSection,
diff --git a/src/components/settings/__tests__/settings-shell.test.tsx b/src/components/settings/__tests__/settings-shell.test.tsx
index b10b03c07..ddca9005d 100644
--- a/src/components/settings/__tests__/settings-shell.test.tsx
+++ b/src/components/settings/__tests__/settings-shell.test.tsx
@@ -63,8 +63,11 @@ describe("SETTINGS_SECTION_SLUGS", () => {
     // Layout hub instead of four standalone nav entries.
     // v1.17.1 — `reminders` is the one "Reminders & Notifications" home and
     // sits right after `notifications`.
+    // v1.18.0 — `modules` ("Was du trackst") sits right after `account` as
+    // the single front door for enabling/disabling secondary domains.
     expect([...SETTINGS_SECTION_SLUGS]).toEqual([
       "account",
+      "modules",
       "integrations",
       "notifications",
       "reminders",
diff --git a/src/components/settings/module-toggle-row.tsx b/src/components/settings/module-toggle-row.tsx
new file mode 100644
index 000000000..47a8cbb23
--- /dev/null
+++ b/src/components/settings/module-toggle-row.tsx
@@ -0,0 +1,85 @@
+"use client";
+
+/**
+ * `<ModuleToggleRow>` — one row in the Settings → Module ("Was du trackst")
+ * hub. v1.18.0.
+ *
+ * Renders a single module: a neutral icon, the i18n label + one-line
+ * description, and a `<Switch>` reflecting the resolved enabled-state. The
+ * row is presentation-only — the parent `<ModulesSection>` owns the mutation
+ * and cache invalidation, so this component stays a pure, easily-tested leaf.
+ *
+ * Two modes:
+ *   - toggleable: the Switch is live; flipping it calls `onToggle(next)`.
+ *   - locked (core domains): the Switch is checked + disabled with a short
+ *     "always on" note, so the always-on measurement engine + meds read as
+ *     deliberately fixed rather than broken. Palette stays neutral — no
+ *     alarming green-when-on / red-when-off tint.
+ */
+
+import type { LucideIcon } from "lucide-react";
+
+import { Label } from "@/components/ui/label";
+import { Switch } from "@/components/ui/switch";
+
+export interface ModuleToggleRowProps {
+  /** Stable key — used for the input id + the test query handle. */
+  moduleKey: string;
+  icon: LucideIcon;
+  label: string;
+  description: string;
+  /** Whether the Switch reads on. Core rows pass `true`. */
+  enabled: boolean;
+  /**
+   * When set the row is read-only: the Switch is locked checked and the
+   * `lockedNote` line renders beneath the description. Core domains use this.
+   */
+  locked?: boolean;
+  /** One-line "core / always on" note, only shown when `locked`. */
+  lockedNote?: string;
+  /** Disable the Switch while a mutation is in flight (toggleable rows). */
+  pending?: boolean;
+  /** Fired with the next desired state on a user toggle (toggleable rows). */
+  onToggle?: (next: boolean) => void;
+}
+
+export function ModuleToggleRow({
+  moduleKey,
+  icon: Icon,
+  label,
+  description,
+  enabled,
+  locked = false,
+  lockedNote,
+  pending = false,
+  onToggle,
+}: ModuleToggleRowProps) {
+  const inputId = `module-toggle-${moduleKey}`;
+  return (
+    <div className="flex items-start justify-between gap-4 py-3">
+      <div className="flex min-w-0 items-start gap-3">
+        <Icon
+          className="text-muted-foreground mt-0.5 h-5 w-5 shrink-0"
+          aria-hidden="true"
+        />
+        <div className="min-w-0 space-y-0.5">
+          <Label htmlFor={inputId} className="text-sm font-medium">
+            {label}
+          </Label>
+          <p className="text-muted-foreground text-xs">{description}</p>
+          {locked && lockedNote ? (
+            <p className="text-muted-foreground/80 text-xs">{lockedNote}</p>
+          ) : null}
+        </div>
+      </div>
+      <Switch
+        id={inputId}
+        checked={locked ? true : enabled}
+        disabled={locked || pending}
+        onCheckedChange={locked ? undefined : (v) => onToggle?.(v)}
+        className="mt-0.5 shrink-0"
+        aria-label={label}
+      />
+    </div>
+  );
+}
diff --git a/src/components/settings/modules-section.tsx b/src/components/settings/modules-section.tsx
new file mode 100644
index 000000000..7c81829d3
--- /dev/null
+++ b/src/components/settings/modules-section.tsx
@@ -0,0 +1,175 @@
+"use client";
+
+/**
+ * `<ModulesSection>` — Settings → Module ("Was du trackst") hub. v1.18.0.
+ *
+ * The one place a user decides which secondary domains HealthLog surfaces.
+ * Each toggleable module (mood, sleep, glucose, workouts, recovery, labs,
+ * achievements, coach, insights, doctor report, cycle) gets a row with an
+ * icon, label, one-line description, and a `<Switch>`. Flipping a switch
+ * PATCHes `/api/auth/me/modules` (a DISABLED allowlist; the endpoint refuses
+ * core keys) and then invalidates the `authMe()` query so the nav, Insights
+ * pills, and dashboard tiles re-gate live off `useAuth().user.modules`.
+ *
+ * The four CORE domains (weight, blood pressure, pulse, medications) render
+ * as a separate read-only "always on" group — locked switches with a short
+ * note — so the always-on measurement engine + meds read as deliberately
+ * fixed, never disableable. Palette stays neutral throughout; this is a
+ * calm configuration surface, not an alarm panel.
+ *
+ * State source is `useAuth().user.modules` (the resolved `/auth/me` map).
+ * A module is enabled unless its key is explicitly `false` — default-on.
+ */
+
+import { useMutation, useQueryClient } from "@tanstack/react-query";
+import { toast } from "sonner";
+import {
+  Activity,
+  Award,
+  Blocks,
+  CalendarHeart,
+  Droplet,
+  Dumbbell,
+  FileText,
+  HeartPulse,
+  Lock,
+  MessageCircleHeart,
+  Moon,
+  Pill,
+  Scale,
+  Smile,
+  Sparkles,
+  TestTube,
+  type LucideIcon,
+} from "lucide-react";
+
+import { SettingsCardHeader } from "@/components/settings/_card-header";
+import { ModuleToggleRow } from "@/components/settings/module-toggle-row";
+import { useAuth } from "@/hooks/use-auth";
+import { useTranslations } from "@/lib/i18n/context";
+import { apiPatch } from "@/lib/api/api-fetch";
+import { queryKeys } from "@/lib/query-keys";
+import {
+  CORE_DOMAIN_KEYS,
+  MODULE_REGISTRY,
+  type CoreDomainKey,
+  type ModuleKey,
+} from "@/lib/modules/registry";
+
+/** Neutral Lucide glyph per toggleable module. */
+const MODULE_ICONS: Record<ModuleKey, LucideIcon> = {
+  cycle: CalendarHeart,
+  mood: Smile,
+  sleep: Moon,
+  glucose: Droplet,
+  workouts: Dumbbell,
+  recovery: Activity,
+  labs: TestTube,
+  achievements: Award,
+  coach: MessageCircleHeart,
+  insights: Sparkles,
+  doctorReport: FileText,
+};
+
+/** Neutral Lucide glyph per core (always-on) domain. */
+const CORE_ICONS: Record<CoreDomainKey, LucideIcon> = {
+  weight: Scale,
+  bloodPressure: HeartPulse,
+  pulse: Activity,
+  medications: Pill,
+};
+
+export function ModulesSection() {
+  const { t } = useTranslations();
+  const { user } = useAuth();
+  const queryClient = useQueryClient();
+
+  const modules = user?.modules ?? {};
+
+  const toggle = useMutation({
+    // Factory-routed; the in-repo eslint rule forbids a bare literal here.
+    mutationKey: queryKeys.modulesPrefs(),
+    mutationFn: async (vars: { key: ModuleKey; enabled: boolean }) => {
+      // DISABLED allowlist: send only the single key the user flipped.
+      return apiPatch("/api/auth/me/modules", { [vars.key]: vars.enabled });
+    },
+    onSuccess: () => {
+      // Re-gate every surface that reads the module map off /auth/me: nav,
+      // Insights pills, dashboard tiles, quick-add, search.
+      void queryClient.invalidateQueries({ queryKey: queryKeys.authMe() });
+      toast.success(t("settings.sections.modules.saved"));
+    },
+    onError: () => {
+      toast.error(t("settings.sections.modules.error"));
+    },
+  });
+
+  return (
+    <section
+      aria-labelledby="settings-section-modules-title"
+      className="space-y-6"
+    >
+      <header className="space-y-1">
+        <h1 id="settings-section-modules-title" className="sr-only">
+          {t("settings.sections.modules.title")}
+        </h1>
+        <p className="text-muted-foreground text-sm">
+          {t("settings.sections.modules.description")}
+        </p>
+      </header>
+
+      {/* Toggleable modules */}
+      <div className="bg-card border-border rounded-xl border p-4 sm:p-6">
+        <SettingsCardHeader
+          icon={Blocks}
+          title={t("settings.sections.modules.toggleable.title")}
+          description={t("settings.sections.modules.toggleable.description")}
+          className="mb-2"
+        />
+        <div className="divide-border divide-y pl-7">
+          {(Object.keys(MODULE_REGISTRY) as ModuleKey[]).map((key) => {
+            const def = MODULE_REGISTRY[key];
+            // Default-on: a module is enabled unless explicitly `false`.
+            const enabled = modules[key] !== false;
+            return (
+              <ModuleToggleRow
+                key={key}
+                moduleKey={key}
+                icon={MODULE_ICONS[key]}
+                label={t(def.labelKey)}
+                description={t(def.descriptionKey)}
+                enabled={enabled}
+                pending={toggle.isPending}
+                onToggle={(next) => toggle.mutate({ key, enabled: next })}
+              />
+            );
+          })}
+        </div>
+      </div>
+
+      {/* Core domains — always on, read-only */}
+      <div className="bg-card border-border rounded-xl border p-4 sm:p-6">
+        <SettingsCardHeader
+          icon={Lock}
+          title={t("settings.sections.modules.core.title")}
+          description={t("settings.sections.modules.core.description")}
+          className="mb-2"
+        />
+        <div className="divide-border divide-y pl-7">
+          {CORE_DOMAIN_KEYS.map((key) => (
+            <ModuleToggleRow
+              key={key}
+              moduleKey={key}
+              icon={CORE_ICONS[key]}
+              label={t(`modules.${key}.label`)}
+              description={t(`modules.${key}.description`)}
+              enabled
+              locked
+              lockedNote={t("settings.sections.modules.core.note")}
+            />
+          ))}
+        </div>
+      </div>
+    </section>
+  );
+}
diff --git a/src/components/settings/section-placeholder.tsx b/src/components/settings/section-placeholder.tsx
index e437f3b95..846d3c3af 100644
--- a/src/components/settings/section-placeholder.tsx
+++ b/src/components/settings/section-placeholder.tsx
@@ -14,6 +14,7 @@
 import {
   AlarmClock,
   Bell,
+  Blocks,
   Download,
   Info,
   KeyRound,
@@ -36,6 +37,7 @@ import type { SettingsSectionSlug } from "./section-slugs";
 
 const SLUG_ICON: Record<SettingsSectionSlug, LucideIcon> = {
   account: User,
+  modules: Blocks,
   integrations: Link2,
   notifications: Bell,
   reminders: AlarmClock,
diff --git a/src/components/settings/section-slugs.ts b/src/components/settings/section-slugs.ts
index 87e9723b3..b2e65c233 100644
--- a/src/components/settings/section-slugs.ts
+++ b/src/components/settings/section-slugs.ts
@@ -34,6 +34,9 @@
 // the hub is consolidation by linking.
 export const SETTINGS_SECTION_SLUGS = [
   "account",
+  // v1.18.0 — `modules` ("Was du trackst") sits right after account: the
+  // single front door for enabling/disabling secondary tracking domains.
+  "modules",
   "integrations",
   "notifications",
   "reminders",
diff --git a/src/components/settings/settings-shell.tsx b/src/components/settings/settings-shell.tsx
index 28d2c168d..1c5c14309 100644
--- a/src/components/settings/settings-shell.tsx
+++ b/src/components/settings/settings-shell.tsx
@@ -20,6 +20,7 @@ import { usePathname } from "next/navigation";
 import {
   AlarmClock,
   Bell,
+  Blocks,
   Download,
   Info,
   KeyRound,
@@ -80,6 +81,13 @@ interface SettingsSection {
  */
 export const SETTINGS_SECTIONS: readonly SettingsSection[] = [
   { slug: "account", titleKey: "settings.sections.account.title", icon: User },
+  // v1.18.0 — the "Was du trackst" hub. Sits right below Account: the one
+  // place to enable/disable the secondary tracking domains.
+  {
+    slug: "modules",
+    titleKey: "settings.sections.modules.title",
+    icon: Blocks,
+  },
   {
     slug: "integrations",
     titleKey: "settings.sections.integrations.title",
diff --git a/src/lib/query-keys/settings.ts b/src/lib/query-keys/settings.ts
index 83fdd03c0..a085dd9ce 100644
--- a/src/lib/query-keys/settings.ts
+++ b/src/lib/query-keys/settings.ts
@@ -21,6 +21,15 @@ export const settingsKeys = {
   /** v1.8.5 — user-level injection-site preferences (global exclusion). */
   injectionSitePrefs: () => ["settings", "injection-site-prefs"] as const,
 
+  /**
+   * v1.18.0 — the per-user module enable/disable map behind
+   * `GET/PATCH /api/auth/me/modules`. Used as the Module-hub mutation key;
+   * the resolved map itself rides on `authMe()` (the `/auth/me` payload),
+   * so the toggle mutation invalidates `authMe()` to re-gate the nav,
+   * Insights pills, and dashboard tiles in lockstep.
+   */
+  modulesPrefs: () => ["settings", "modules"] as const,
+
   apiVersion: () => ["api", "version"] as const,
   publicVersion: () => ["public", "version"] as const,
   /** v1.15.12 H1 — admin overview "update available" check against the