feat: update versioning and add activity last updated endpoint

- Bumped application version to 0.9r and updated build date to 2026-04-20.
- Added a new endpoint `/activity-last-updated` to retrieve the last activity date for a user, optimizing data retrieval for activity history.
- Updated the frontend to utilize the new endpoint, enhancing the ActivitySection with the last activity date display.
- Refactored the History component to streamline data loading and improve user experience with activity insights.

backend/data_layer/fitness_viz.py

@@ -59,6 +59,15 @@ def _last_activity_date(profile_id: str) -> Optional[str]:
         return _iso(row["d"])
 
 
+def get_activity_last_updated_iso(profile_id: str) -> Optional[str]:
+    """
+    Leichtgewicht: letztes activity_log.date — identisch zu ``last_updated`` im Fitness-Viz-Bundle.
+
+    Für History-Header o. Ä. ohne vollständige Aktivitätsliste (Phase A, Issue-53-Pfad).
+    """
+    return _last_activity_date(profile_id)
+
+
 def get_fitness_dashboard_viz_bundle(profile_id: str, days: int) -> Dict[str, Any]:
     """
     Bundle für Fitness-Übersicht: KPI-Kacheln + eingebettete Chart-Payloads (Chart.js-Format).

backend/routers/charts.py

@@ -33,7 +33,7 @@ from data_layer.body_metrics import (
 )
 from data_layer.body_viz import get_body_history_viz_bundle
 from data_layer.nutrition_viz import get_nutrition_history_viz_bundle
-from data_layer.fitness_viz import get_fitness_dashboard_viz_bundle
+from data_layer.fitness_viz import get_fitness_dashboard_viz_bundle, get_activity_last_updated_iso
 from data_layer.recovery_viz import get_recovery_dashboard_viz_bundle
 from data_layer.history_overview_viz import get_history_overview_viz_bundle
 from data_layer.recovery_chart_payloads import (
@@ -319,6 +319,17 @@ def get_fitness_dashboard_viz(
     return serialize_dates(bundle)
 
 
+@router.get("/activity-last-updated")
+def get_activity_last_updated(session: dict = Depends(require_auth)) -> Dict:
+    """
+    Minimal-Metadatum: letztes Trainingsdatum — gleiche Quelle wie ``last_updated`` im Fitness-Viz-Bundle.
+
+    Vermeidet Massen-Ladevorgänge (z. B. listActivity) nur für Datumsanzeige im Verlauf.
+    """
+    pid = session["profile_id"]
+    return {"last_activity_date": get_activity_last_updated_iso(pid)}
+
+
 @router.get("/recovery-dashboard-viz")
 def get_recovery_dashboard_viz(
     days: int = Query(

backend/version.py

@@ -7,8 +7,8 @@ Semantic Versioning: MAJOR.MINOR.PATCH
 - PATCH: Bugfix, kleine Änderung, Refactor
 """
 
-APP_VERSION = "0.9q"
-BUILD_DATE = "2026-04-11"
+APP_VERSION = "0.9r"
+BUILD_DATE = "2026-04-20"
 DB_SCHEMA_VERSION = "20260409c"  # 048/049 vitals_baseline.source csv + SAVEPOINT Import
 
 MODULE_VERSIONS = {
@@ -36,6 +36,14 @@ MODULE_VERSIONS = {
 }
 
 CHANGELOG = [
+    {
+        "version": "0.9r",
+        "date": "2026-04-20",
+        "changes": [
+            "History Phase A: GET /api/charts/activity-last-updated (data_layer fitness_viz, gleiche Quelle wie last_updated im Fitness-Bundle)",
+            "History: entfernt toten Initial-Load listWeight/listCaliper/listCirc/listNutrition/listActivity(25k); Profil/Insights/Prompts + Activity-Datum",
+        ],
+    },
     {
         "version": "0.9q",
         "date": "2026-04-11",

frontend/src/pages/History.jsx

@@ -1196,14 +1196,12 @@ function NutritionSection({ profile, insights, onRequest, loadingSlug, filterAct
 }
 
 // ── Activity Section — nur Layer-2b-Bundle (+ KI-Insights), keine parallelen Client-Charts ─
-function ActivitySection({ activities, insights, onRequest, loadingSlug, filterActiveSlugs, globalQualityLevel }) {
+function ActivitySection({ activityLastDate, insights, onRequest, loadingSlug, filterActiveSlugs, globalQualityLevel }) {
   const [period, setPeriod] = useState(30)
-  const actList = activities || []
-  const hasList = actList.length > 0
 
   return (
     <div>
-      <SectionHeader title="🏋️ Fitness" to="/activity" toLabel="Alle Einträge" lastUpdated={actList[0]?.date}/>
+      <SectionHeader title="🏋️ Fitness" to="/activity" toLabel="Alle Einträge" lastUpdated={activityLastDate || undefined}/>
       <PeriodSelector value={period} onChange={setPeriod}/>
       <p style={{ fontSize: 11, color: 'var(--text3)', lineHeight: 1.45, marginBottom: 10 }}>
         Fitness und Erholung aus den Data-Layer-Bundles (Issue 53). Zeitraum-Buttons steuern beide Bereiche gleichzeitig.
@@ -1215,7 +1213,7 @@ function ActivitySection({ activities, insights, onRequest, loadingSlug, filterA
       </div>
       <RecoveryDashboardOverview period={period} onPeriodChange={setPeriod} hidePeriodSelector />
 
-      {hasList && globalQualityLevel && globalQualityLevel !== 'all' && (
+      {activityLastDate && globalQualityLevel && globalQualityLevel !== 'all' && (
         <div style={{
           marginTop: 12,
           marginBottom: 12, padding:'8px 12px', borderRadius:8,
@@ -1735,11 +1733,7 @@ export default function History() {
   const { activeProfile } = useProfile()  // Issue #31: Get global quality filter
   const location = useLocation?.() || {}
   const [tab, setTab] = useState((location.state?.tab) || 'overview')
-  const [weights,    setWeights]    = useState([])
-  const [calipers,   setCalipers]   = useState([])
-  const [circs,      setCircs]      = useState([])
-  const [nutrition,  setNutrition]  = useState([])
-  const [activities, setActivities] = useState([])
+  const [activityLastDate, setActivityLastDate] = useState(null)
   const [insights,   setInsights]   = useState([])
   const [prompts,    setPrompts]    = useState([])
   const [profile,    setProfile]    = useState(null)
@@ -1747,15 +1741,15 @@ export default function History() {
   const [loadingSlug,setLoadingSlug]= useState(null)
 
   const loadAll = () => Promise.all([
-    api.listWeight(365), api.listCaliper(), api.listCirc(),
-    api.listNutrition(90), api.listActivity(25_000),
-    api.latestInsights(), api.getProfile(),
+    api.latestInsights(),
+    api.getProfile(),
     api.listPrompts(),
-  ]).then(([w,ca,ci,n,a,ins,p,pr])=>{
-    setWeights(w); setCalipers(ca); setCircs(ci)
-    setNutrition(n); setActivities(a)
-    setInsights(Array.isArray(ins)?ins:[]); setProfile(p)
+    api.getActivityLastUpdated(),
+  ]).then(([ins, p, pr, actMeta]) => {
+    setInsights(Array.isArray(ins) ? ins : [])
+    setProfile(p)
     setPrompts(Array.isArray(pr) ? pr : [])
+    setActivityLastDate(actMeta?.last_activity_date ?? null)
     setLoading(false)
   })
 
@@ -1820,7 +1814,7 @@ export default function History() {
           {tab==='overview'    && <HistoryOverviewSection {...sp}/>}
           {tab==='body'        && <BodySection profile={profile} {...sp}/>}
           {tab==='nutrition'   && <NutritionSection profile={profile} {...sp}/>}
-          {tab==='activity'    && <ActivitySection  activities={activities} globalQualityLevel={activeProfile?.quality_filter_level} {...sp}/>}
+          {tab==='activity'    && <ActivitySection activityLastDate={activityLastDate} globalQualityLevel={activeProfile?.quality_filter_level} {...sp}/>}
           {tab==='photos'      && <PhotoGrid/>}
         </div>
       </div>

frontend/src/utils/api.js

@@ -644,6 +644,8 @@ export const api = {
   /** Layer 2b: Erholung — KPI, Insights, Charts R1–R5 (recovery_metrics) */
   getRecoveryDashboardViz:            (days=28)  => req(`/charts/recovery-dashboard-viz?days=${days}`),
   getHistoryOverviewViz:              (days=30) => req(`/charts/history-overview-viz?days=${days}`),
+  /** Minimal: letztes activity_log.date — wie fitness-dashboard-viz.last_updated */
+  getActivityLastUpdated:            () => req('/charts/activity-last-updated'),
   getWeightEnergyCorrelationChart:   (maxLag=14) => req(`/charts/weight-energy-correlation?max_lag=${maxLag}`),
   getLbmProteinCorrelationChart:      (maxLag=14) => req(`/charts/lbm-protein-correlation?max_lag=${maxLag}`),
   getLoadVitalsCorrelationChart:     (maxLag=14) => req(`/charts/load-vitals-correlation?max_lag=${maxLag}`),