diff --git a/frontend/src/layouts/PlanningLayout.jsx b/frontend/src/layouts/PlanningLayout.jsx
index c11b1b5..1839a1b 100644
--- a/frontend/src/layouts/PlanningLayout.jsx
+++ b/frontend/src/layouts/PlanningLayout.jsx
@@ -1,11 +1,15 @@
-import { Outlet } from 'react-router-dom'
+import { Outlet, useLocation } from 'react-router-dom'
 import PlanningRouteNav from '../components/planning/PlanningRouteNav'
+import { isPlanningUnitEditorPath } from '../utils/planningUnitRoutes'
 
 /** Gemeinsame Hülle für Planung, Rahmenprogramme, Module und Vorlagen. */
 export default function PlanningLayout() {
+  const { pathname } = useLocation()
+  const hideRouteNav = isPlanningUnitEditorPath(pathname)
+
   return (
     <div className="app-page planning-layout">
-      <PlanningRouteNav />
+      {!hideRouteNav ? <PlanningRouteNav /> : null}
       <div className="planning-layout__main">
         <Outlet />
       </div>
diff --git a/frontend/src/pages/TrainingUnitEditPage.jsx b/frontend/src/pages/TrainingUnitEditPage.jsx
index a44eaf8..45b0745 100644
--- a/frontend/src/pages/TrainingUnitEditPage.jsx
+++ b/frontend/src/pages/TrainingUnitEditPage.jsx
@@ -26,9 +26,12 @@ import {
   createEmptyTrainingUnitFormData,
   buildTrainingUnitSavePayload,
   trainingUnitToFormFields,
+  trainingUnitFormSnapshot,
   validateTrainingUnitFormForSave,
 } from '../utils/trainingUnitEditorCore'
 import PageFormEditorChrome from '../components/PageFormEditorChrome'
+import UnsavedChangesPrompt from '../components/UnsavedChangesPrompt'
+import { useBeforeUnloadWhen, useUnsavedChangesBlocker } from '../hooks/useUnsavedChangesBlocker'
 import { buildPlanUnitEditPath, planningHubPathFromReturnState } from '../utils/planningUnitRoutes'
 
 export default function TrainingUnitEditPage() {
@@ -54,6 +57,45 @@ export default function TrainingUnitEditPage() {
   const formRef = useRef(formData)
   formRef.current = formData
 
+  const baselineRef = useRef(null)
+  const [baselineReady, setBaselineReady] = useState(false)
+  const [bypassDirty, setBypassDirty] = useState(false)
+
+  const dirtySignature = trainingUnitFormSnapshot(formRef.current, {
+    editingUnit,
+    draftPlanTemplateId,
+  })
+
+  useEffect(() => {
+    baselineRef.current = null
+    setBaselineReady(false)
+    setBypassDirty(false)
+  }, [isNew, unitId])
+
+  useEffect(() => {
+    if (loading) return undefined
+    const handle = window.setTimeout(() => {
+      baselineRef.current = trainingUnitFormSnapshot(formRef.current, {
+        editingUnit,
+        draftPlanTemplateId,
+      })
+      setBaselineReady(true)
+    }, 120)
+    return () => clearTimeout(handle)
+    // Baseline nur nach initialem Laden — nicht bei Template-/Form-Änderungen im Editor
+    // eslint-disable-next-line react-hooks/exhaustive-deps -- editingUnit/draftPlanTemplateId bewusst ausgeschlossen
+  }, [loading, isNew, unitId])
+
+  const formDirtyEffective =
+    baselineReady &&
+    baselineRef.current != null &&
+    !bypassDirty &&
+    !loading &&
+    dirtySignature !== baselineRef.current
+
+  const blocker = useUnsavedChangesBlocker(Boolean(formDirtyEffective && !saving))
+  useBeforeUnloadWhen(Boolean(formDirtyEffective && !saving))
+
   const [exercisePickerOpen, setExercisePickerOpen] = useState(false)
   const [exercisePickerTarget, setExercisePickerTarget] = useState(null)
   const [planningPeekCtx, setPlanningPeekCtx] = useState(null)
@@ -400,10 +442,18 @@ export default function TrainingUnitEditPage() {
   const reloadUnitAfterSave = useCallback(
     async (savedId) => {
       const fullUnit = await api.getTrainingUnit(savedId)
+      const nextDraftTemplateId = fullUnit.plan_template_id ? String(fullUnit.plan_template_id) : ''
       setEditingUnit(fullUnit)
+      setDraftPlanTemplateId(nextDraftTemplateId)
       let sections = normalizeUnitToForm(fullUnit)
       sections = await enrichSectionsWithVariants(sections)
-      setFormData(trainingUnitToFormFields(fullUnit, sections))
+      const nextForm = trainingUnitToFormFields(fullUnit, sections)
+      setFormData(nextForm)
+      baselineRef.current = trainingUnitFormSnapshot(nextForm, {
+        editingUnit: fullUnit,
+        draftPlanTemplateId: nextDraftTemplateId,
+      })
+      setBypassDirty(false)
       if (!isNew && savedId !== unitId) {
         navigate(buildPlanUnitEditPath(savedId), { replace: true, state: location.state })
       }
@@ -448,6 +498,11 @@ export default function TrainingUnitEditPage() {
     [formData, editingUnit, draftPlanTemplateId, toast, goBack, reloadUnitAfterSave]
   )
 
+  const handleUnsavedDialogSave = async () => {
+    const ok = await handleSubmit(null, { closeAfter: false })
+    if (ok) blocker.proceed()
+  }
+
   const actionConfig = useMemo(
     () => ({
       formId: 'planning-unit-form',
@@ -726,6 +781,14 @@ export default function TrainingUnitEditPage() {
         peekExtras={planningPeekCtx?.peekExtras ?? undefined}
         onClose={() => setPlanningPeekCtx(null)}
       />
+
+      <UnsavedChangesPrompt
+        blocker={blocker}
+        isBusy={saving}
+        onSave={handleUnsavedDialogSave}
+        onDiscardWithoutSave={() => setBypassDirty(true)}
+        detail="Du hast ungespeicherte Änderungen vorgenommen. Möchtest du die Seite wirklich verlassen?"
+      />
     </PageFormEditorChrome>
   )
 }
diff --git a/frontend/src/utils/planningUnitRoutes.js b/frontend/src/utils/planningUnitRoutes.js
index fa639ac..ba69613 100644
--- a/frontend/src/utils/planningUnitRoutes.js
+++ b/frontend/src/utils/planningUnitRoutes.js
@@ -64,6 +64,13 @@ export function buildPlanningHubReturnState(hubState = {}) {
   }
 }
 
+/** @param {string} pathname */
+export function isPlanningUnitEditorPath(pathname) {
+  if (!pathname) return false
+  if (pathname === '/planning/units/new') return true
+  return /^\/planning\/units\/\d+\/edit$/.test(pathname)
+}
+
 /** @param {ReturnType<typeof buildPlanningHubReturnState>|null|undefined} state */
 export function planningHubPathFromReturnState(state) {
   if (!state || state.v !== 1) return PLANNING_HUB_PATH
diff --git a/frontend/src/utils/planningUnitRoutes.test.js b/frontend/src/utils/planningUnitRoutes.test.js
index 5df40e8..5b738ee 100644
--- a/frontend/src/utils/planningUnitRoutes.test.js
+++ b/frontend/src/utils/planningUnitRoutes.test.js
@@ -3,6 +3,7 @@ import {
   buildPlanUnitEditPath,
   buildPlanUnitNewPath,
   buildPlanningHubReturnState,
+  isPlanningUnitEditorPath,
   legacyPlanningUnitDeepLinkTarget,
   parsePlanningHubQuery,
   planningHubPathFromReturnState,
@@ -22,6 +23,13 @@ describe('planningUnitRoutes', () => {
     expect(buildPlanUnitNewPath()).toBe('/planning/units/new')
   })
 
+  it('isPlanningUnitEditorPath', () => {
+    expect(isPlanningUnitEditorPath('/planning/units/new')).toBe(true)
+    expect(isPlanningUnitEditorPath('/planning/units/42/edit')).toBe(true)
+    expect(isPlanningUnitEditorPath('/planning')).toBe(false)
+    expect(isPlanningUnitEditorPath('/planning/training-modules')).toBe(false)
+  })
+
   it('legacyPlanningUnitDeepLinkTarget', () => {
     expect(legacyPlanningUnitDeepLinkTarget('unit=5')).toBe('/planning/units/5/edit')
     expect(legacyPlanningUnitDeepLinkTarget('unit=5&debrief=1')).toBe(
diff --git a/frontend/src/utils/trainingUnitEditorCore.js b/frontend/src/utils/trainingUnitEditorCore.js
index 9b05e53..a03a905 100644
--- a/frontend/src/utils/trainingUnitEditorCore.js
+++ b/frontend/src/utils/trainingUnitEditorCore.js
@@ -131,3 +131,11 @@ export function validateTrainingUnitFormForSave(formData) {
   }
   return { ok: true }
 }
+
+/** Stabiler Fingerabdruck für Dirty-Check (identisch zum Save-Payload). */
+export function trainingUnitFormSnapshot(
+  formData,
+  { editingUnit = null, draftPlanTemplateId = '' } = {}
+) {
+  return JSON.stringify(buildTrainingUnitSavePayload(formData, { editingUnit, draftPlanTemplateId }))
+}
diff --git a/frontend/src/utils/trainingUnitEditorCore.test.js b/frontend/src/utils/trainingUnitEditorCore.test.js
index 3866e25..d320900 100644
--- a/frontend/src/utils/trainingUnitEditorCore.test.js
+++ b/frontend/src/utils/trainingUnitEditorCore.test.js
@@ -2,6 +2,7 @@ import { describe, expect, it } from 'vitest'
 import {
   buildTrainingUnitSavePayload,
   createEmptyTrainingUnitFormData,
+  trainingUnitFormSnapshot,
   validateTrainingUnitFormForSave,
 } from './trainingUnitEditorCore.js'
 
@@ -42,4 +43,11 @@ describe('trainingUnitEditorCore', () => {
     expect(payload.assistant_trainer_profile_ids).toBeNull()
     expect(payload.group_id).toBeUndefined()
   })
+
+  it('trainingUnitFormSnapshot matches save payload', () => {
+    const formData = createEmptyTrainingUnitFormData({ groupId: '5', plannedDate: '2026-05-10' })
+    const snap = trainingUnitFormSnapshot(formData, { draftPlanTemplateId: '3' })
+    const payload = buildTrainingUnitSavePayload(formData, { draftPlanTemplateId: '3' })
+    expect(snap).toBe(JSON.stringify(payload))
+  })
 })