Refactor TrainingCoachPage and TrainingUnitRunPage to enhance coach branching functionality

- Updated TrainingCoachPage to implement branching logic for coach steps, allowing for improved navigation through training phases.
- Enhanced session storage handling to manage branch picks and streamline state management during training sessions.
- Modified TrainingUnitRunPage to update links for coaching views, reflecting the new branching structure and improving user experience.
- Introduced new utility functions in trainingPlanUtils for managing coach branch picks and timeline navigation, optimizing data handling across components.

frontend/src/pages/TrainingCoachPage.jsx

@@ -1,6 +1,5 @@
 /**
- * Coach-Modus: eine Position nach der anderen mit Assistentenhinweisen, Zeitnahme und optionaler Nachbereitung.
- * Timeline: flach in Phasen-/Stream-Reihenfolge (flattenPlanTimeline).
+ * Coach-Modus: Schrittfolge mit Split-Punkten (branch_gate), Stream-Wahl pro paralleler Phase, Assistenz und Zeitnahme.
  */
 import React, { useCallback, useEffect, useMemo, useRef, useState } from 'react'
 import { Link, useNavigate, useParams, useSearchParams } from 'react-router-dom'
@@ -8,17 +7,23 @@ import api from '../utils/api'
 import ExerciseFullContent from '../components/ExerciseFullContent'
 import ExercisePeekModal from '../components/ExercisePeekModal'
 import {
+  COACH_ENTRY_BRANCH_GATE,
+  coachBranchPicksStepStorageSuffix,
+  coachBranchPicksStorageKey,
+  coachOutlineGroupsFromTimeline,
   durationOverridesMapFromDeltas,
+  findCoachTimelineJumpIndexForPhase,
   flattenPlanTimeline,
   itemStableKey,
   listCoachStreamFocusOptions,
+  mergeCoachBranchPicksWithUrlFocus,
+  normalizeCoachBranchPicks,
   sectionsToPutPayload,
   summarizeTimelineEntry,
 } from '../utils/trainingPlanUtils'
 
-function storageStepKey(unitId, coachFocus) {
-  if (coachFocus == null) return `sj_coach_step_${unitId}_full`
-  return `sj_coach_step_${unitId}_po${coachFocus.phaseOrder}-so${coachFocus.streamOrder}`
+function storageStepKey(unitId, mergedPicks) {
+  return `sj_coach_step_${unitId}_${coachBranchPicksStepStorageSuffix(mergedPicks)}`
 }
 
 function storageDeltasKey(unitId) {
@@ -58,14 +63,16 @@ function CoachControlsBand({
   showJumpToTimerOwnerRow = true,
   onJumpToTimerOwner,
   timerOwnerLabelIndex,
+  branchGateMode = false,
 }) {
   const disPrev = step <= 0
-  const disNext = step >= timelineLength - 1
+  const disNext = branchGateMode || step >= timelineLength - 1
   const alive = runStartAt != null || pausedAccumMs > 0
-  const canApplyForOwner = roundedMinForApply != null && roundedMinForApply >= 1
+  const canApplyForOwner = !branchGateMode && roundedMinForApply != null && roundedMinForApply >= 1
   const istLabelMin = roundedMinForApply == null ? '—' : String(roundedMinForApply)
-  const doneLabel =
-    timelineLength <= 1
+  const doneLabel = branchGateMode
+    ? 'Zuerst Gruppe wählen'
+    : timelineLength <= 1
       ? 'Nachbereitung öffnen'
       : isLastCoachStep
         ? 'Nachbereitung & Ist-Zeit'
@@ -109,6 +116,7 @@ function CoachControlsBand({
                 type="button"
                 className="btn btn-primary"
                 style={{ minHeight: '44px', flex: '1 1 auto', fontWeight: 700 }}
+                disabled={branchGateMode}
                 onClick={onTimerStart}
               >
                 ▶ Start{alive ? ` · ${clockStr}` : ''}
@@ -121,7 +129,7 @@ function CoachControlsBand({
             <button type="button" className="btn btn-secondary" style={{ minHeight: '44px', flex: '0 1 auto', fontWeight: 600 }} disabled={!canApplyForOwner} onClick={onApplyActual}>
               Ist ({istLabelMin}&nbsp;Min)
             </button>
-            {alive && (
+            {alive && !branchGateMode && (
               <button
                 type="button"
                 className="btn btn-secondary"
@@ -137,6 +145,7 @@ function CoachControlsBand({
             type="button"
             className="btn btn-primary"
             style={{ width: '100%', minHeight: '44px', fontWeight: 700, lineHeight: 1.2, padding: '6px 10px', whiteSpace: 'normal', textAlign: 'center' }}
+            disabled={branchGateMode}
             onClick={onDone}
           >
             {doneLabel}
@@ -176,6 +185,8 @@ export default function TrainingCoachPage() {
   const [coachDebriefPhase, setCoachDebriefPhase] = useState(false)
 
   const [step, setStep] = useState(0)
+  const [branchPicks, setBranchPicks] = useState({})
+  const [streamChoiceHint, setStreamChoiceHint] = useState(null)
   const [deltas, setDeltas] = useState({})
 
   const [runStartAt, setRunStartAt] = useState(null)
@@ -207,15 +218,32 @@ export default function TrainingCoachPage() {
     return { phaseOrder: po, streamOrder: so }
   }, [searchParams, unit])
 
+  const mergedPicks = useMemo(
+    () => mergeCoachBranchPicksWithUrlFocus(branchPicks, coachFocus),
+    [branchPicks, coachFocus]
+  )
+
   const streamFocusOptions = useMemo(() => (unit ? listCoachStreamFocusOptions(unit) : []), [unit])
 
-  const focusKey = coachFocus ? `${coachFocus.phaseOrder}-${coachFocus.streamOrder}` : 'full'
+  const navigationKey = coachBranchPicksStepStorageSuffix(mergedPicks)
+
+  const streamQuickSelectValue = useMemo(() => {
+    for (let i = 0; i < streamFocusOptions.length; i++) {
+      const o = streamFocusOptions[i]
+      if (mergedPicks[o.phaseOrder] === o.streamOrder) return o.valueKey
+    }
+    return ''
+  }, [streamFocusOptions, mergedPicks])
 
   const hasStreamSelectParams =
     (searchParams.get('po') != null && searchParams.get('po') !== '') ||
     (searchParams.get('so') != null && searchParams.get('so') !== '')
   const streamParamsInvalid = Boolean(unit && hasStreamSelectParams && !coachFocus)
 
+  const timeline = useMemo(() => flattenPlanTimeline(unit, mergedPicks), [unit, mergedPicks])
+
+  const outlineGroups = useMemo(() => coachOutlineGroupsFromTimeline(timeline), [timeline])
+
   useEffect(() => {
     if (!unitId || Number.isNaN(idNum)) {
       setLoadError('Ungültige Trainingseinheit')
@@ -230,6 +258,16 @@ export default function TrainingCoachPage() {
       try {
         await reloadUnit()
         if (cancelled) return
+        let nextBranchPicks = {}
+        try {
+          const br = sessionStorage.getItem(coachBranchPicksStorageKey(idNum))
+          if (br) {
+            const o = JSON.parse(br)
+            if (o && typeof o === 'object') nextBranchPicks = normalizeCoachBranchPicks(o)
+          }
+        } catch {
+          /* ignore */
+        }
         try {
           const raw = sessionStorage.getItem(storageDeltasKey(idNum))
           if (raw) {
@@ -244,6 +282,10 @@ export default function TrainingCoachPage() {
         } catch {
           /* ignore */
         }
+        if (!cancelled) {
+          setBranchPicks(nextBranchPicks)
+          setStreamChoiceHint(null)
+        }
       } catch (e) {
         if (!cancelled) setLoadError(e.message || 'Laden fehlgeschlagen')
       } finally {
@@ -272,10 +314,52 @@ export default function TrainingCoachPage() {
     }
   }, [unit, searchParams, setSearchParams])
 
+  useEffect(() => {
+    if (!unit) return
+    const ab = searchParams.get('atBranch')
+    if (ab == null || ab === '') return
+    const po = parseInt(ab, 10)
+    const phaseOrders = [...new Set(streamFocusOptions.map((o) => o.phaseOrder))]
+    if (!Number.isFinite(po) || !phaseOrders.includes(po)) {
+      const next = new URLSearchParams(searchParams)
+      next.delete('atBranch')
+      next.delete('preferSo')
+      setSearchParams(next, { replace: true })
+    }
+  }, [unit, searchParams, setSearchParams, streamFocusOptions])
+
+  useEffect(() => {
+    if (!unit || timeline.length === 0) return
+    const ab = searchParams.get('atBranch')
+    if (ab == null || ab === '') return
+    const po = parseInt(ab, 10)
+    if (!Number.isFinite(po)) return
+    const prefRaw = searchParams.get('preferSo')
+    const pref = prefRaw != null && prefRaw !== '' ? parseInt(prefRaw, 10) : NaN
+    const ix = findCoachTimelineJumpIndexForPhase(timeline, po, Number.isFinite(pref) ? pref : null)
+    if (ix >= 0) {
+      setStep(ix)
+      if (Number.isFinite(pref)) setStreamChoiceHint({ phaseOrder: po, streamOrder: pref })
+    }
+    const next = new URLSearchParams(searchParams)
+    next.delete('atBranch')
+    next.delete('preferSo')
+    setSearchParams(next, { replace: true })
+  }, [unit, timeline, searchParams, setSearchParams])
+
   useEffect(() => {
     if (Number.isNaN(idNum)) return
-    sessionStorage.setItem(storageStepKey(idNum, coachFocus), String(step))
-  }, [idNum, coachFocus, step])
+    try {
+      sessionStorage.setItem(coachBranchPicksStorageKey(idNum), JSON.stringify(branchPicks))
+    } catch {
+      /* quota */
+    }
+  }, [idNum, branchPicks])
+
+  useEffect(() => {
+    if (Number.isNaN(idNum)) return
+    sessionStorage.setItem(storageStepKey(idNum, mergedPicks), String(step))
+  }, [idNum, mergedPicks, step])
 
   useEffect(() => {
     try {
@@ -299,8 +383,6 @@ export default function TrainingCoachPage() {
     return () => clearInterval(iv)
   }, [runStartAt])
 
-  const timeline = useMemo(() => flattenPlanTimeline(unit, coachFocus), [unit, coachFocus])
-
   const clampStep = (s, len = timeline.length) =>
     Math.max(0, Math.min(s, Math.max(len - 1, 0)))
 
@@ -333,16 +415,16 @@ export default function TrainingCoachPage() {
     }
     const prev = coachFocusResetRef.current
     if (prev === null) {
-      coachFocusResetRef.current = focusKey
-    } else if (prev !== focusKey) {
-      coachFocusResetRef.current = focusKey
+      coachFocusResetRef.current = navigationKey
+    } else if (prev !== navigationKey) {
+      coachFocusResetRef.current = navigationKey
       setCoachDebriefPhase(false)
       timerReset()
     } else {
       return
     }
     try {
-      const raw = sessionStorage.getItem(storageStepKey(idNum, coachFocus))
+      const raw = sessionStorage.getItem(storageStepKey(idNum, mergedPicks))
       const s = parseInt(raw, 10)
       const maxIdx = Math.max(0, timeline.length - 1)
       if (!Number.isNaN(s) && s >= 0) setStep(Math.min(s, maxIdx))
@@ -350,7 +432,7 @@ export default function TrainingCoachPage() {
     } catch {
       setStep(0)
     }
-  }, [unit, idNum, focusKey, coachFocus, timeline.length, timerReset])
+  }, [unit, idNum, navigationKey, mergedPicks, timeline.length, timerReset])
 
   const elapsedMs =
     pausedAccumMs + (runStartAt != null ? Date.now() - runStartAt : 0)
@@ -367,7 +449,10 @@ export default function TrainingCoachPage() {
     timerOwningStep != null &&
     step !== timerOwningStep &&
     (runStartAt != null || pausedAccumMs > 0)
-  const isLastCoachStep = timeline.length > 0 && step >= timeline.length - 1
+  const isLastCoachStep =
+    timeline.length > 0 &&
+    step >= timeline.length - 1 &&
+    currentEntry?.entryKind !== COACH_ENTRY_BRANCH_GATE
 
   const timerStart = () => {
     setRunStartAt(Date.now())
@@ -393,12 +478,27 @@ export default function TrainingCoachPage() {
     timerPause()
   }
 
+  const pickStreamForPhase = useCallback(
+    (phaseOrder, streamOrder) => {
+      if (!Number.isFinite(phaseOrder) || !Number.isFinite(streamOrder)) return
+      setStreamChoiceHint(null)
+      setBranchPicks((prev) => ({ ...normalizeCoachBranchPicks(prev), [phaseOrder]: streamOrder }))
+      timerReset()
+      setCoachDebriefPhase(false)
+      setSearchParams({ po: String(phaseOrder), so: String(streamOrder) }, { replace: true })
+    },
+    [timerReset, setSearchParams]
+  )
+
+  const atBranchGate = currentEntry?.entryKind === COACH_ENTRY_BRANCH_GATE
+
   const goPrev = () => setStep((s) => clampStep(s - 1))
   const goNext = () => setStep((s) => clampStep(s + 1))
 
   const markCurrentDoneAdvance = () => {
     const ownerIdx = timerOwningStep != null ? timerOwningStep : step
     const ent = timeline[ownerIdx]
+    if (ent?.entryKind === COACH_ENTRY_BRANCH_GATE) return
     const item = ent?.item
     if (item?.item_type === 'exercise' && elapsedMs > 650) {
       const key = itemStableKey(item, ent.secOrder, ent.ii)
@@ -420,9 +520,20 @@ export default function TrainingCoachPage() {
     setStep((s) => clampStep(s + 1, timeline.length))
   }
 
+  useEffect(() => {
+    if (!atBranchGate) return
+    if (runStartAt != null || pausedAccumMs > 0) timerReset()
+  }, [step, atBranchGate, runStartAt, pausedAccumMs, timerReset])
+
   const durationOverridesForApi = useMemo(() => durationOverridesMapFromDeltas(unit, deltas), [unit, deltas])
 
   useEffect(() => {
+    if (currentEntry?.entryKind === COACH_ENTRY_BRANCH_GATE) {
+      setCatalogExercise(null)
+      setCatalogError(null)
+      setCatalogLoading(false)
+      return
+    }
     const item = currentEntry?.item
     if (!item || item.item_type === 'note') {
       setCatalogExercise(null)
@@ -458,7 +569,7 @@ export default function TrainingCoachPage() {
     return () => {
       cancelled = true
     }
-  }, [step, currentEntry?.item?.exercise_id, currentEntry?.item?.exercise_variant_id, currentEntry?.item?.item_type])
+  }, [step, currentEntry?.entryKind, currentEntry?.item?.exercise_id, currentEntry?.item?.exercise_variant_id, currentEntry?.item?.item_type])
 
   const handleSaveDebrief = async () => {
     setSaveOk(null)
@@ -482,10 +593,13 @@ export default function TrainingCoachPage() {
       try {
         sessionStorage.removeItem(storageDeltasKey(idNum))
         sessionStorage.removeItem(storageDebriefKey(idNum))
+        sessionStorage.removeItem(coachBranchPicksStorageKey(idNum))
       } catch {
         /* ignore */
       }
       setDeltas({})
+      setBranchPicks({})
+      setStreamChoiceHint(null)
       setCoachDebriefPhase(false)
       setSaveOk('Gespeichert.')
       setDebriefOpen(false)
@@ -551,19 +665,22 @@ export default function TrainingCoachPage() {
             <select
               className="form-input"
               style={{ minWidth: 'min(220px, 72vw)', margin: 0, padding: '6px 8px', fontSize: '0.82rem' }}
-              value={coachFocus ? `${coachFocus.phaseOrder}-${coachFocus.streamOrder}` : ''}
+              value={streamQuickSelectValue}
               onChange={(e) => {
                 setCoachDebriefPhase(false)
                 timerReset()
                 const v = e.target.value
-                if (!v) setSearchParams({}, { replace: true })
-                else {
+                if (!v) {
+                  setBranchPicks({})
+                  setStreamChoiceHint(null)
+                  setSearchParams({}, { replace: true })
+                } else {
                   const [ppo, sso] = v.split('-').map((x) => parseInt(x, 10))
-                  setSearchParams({ po: String(ppo), so: String(sso) }, { replace: true })
+                  pickStreamForPhase(ppo, sso)
                 }
               }}
             >
-              <option value="">Gesamtplan (alle Gruppen)</option>
+              <option value="">Ablauf mit Split-Punkten (Standard)</option>
               {streamFocusOptions.map((o) => (
                 <option key={o.valueKey} value={o.valueKey}>
                   {o.label}
@@ -617,50 +734,86 @@ export default function TrainingCoachPage() {
           {unit.planned_time_start && ` · ${String(unit.planned_time_start).slice(0, 5)}`}
           {unit.planned_focus ? ` · ${unit.planned_focus}` : ''}
         </h1>
-        {coachFocus ? (
-          <p style={{ fontSize: '0.8rem', color: 'var(--text2)', margin: '8px 0 0', lineHeight: 1.35 }}>
-            Fokus:{' '}
-            {streamFocusOptions.find((o) => o.phaseOrder === coachFocus.phaseOrder && o.streamOrder === coachFocus.streamOrder)
-              ?.label ?? `Phase ${coachFocus.phaseOrder} · Gruppe ${coachFocus.streamOrder + 1}`}
-            {' · '}
-            Ganzgruppen-Abschnitte bleiben voll sichtbar; in der gewählten Split-Phase nur diese Spalte.
+        {streamFocusOptions.length > 0 ? (
+          <p style={{ fontSize: '0.8rem', color: 'var(--text2)', margin: '8px 0 0', lineHeight: 1.4 }}>
+            Parallele Phasen erscheinen als Schritt <strong>Gruppe wählen</strong> — kein Durcheinander mehr aus
+            verschränkten Streams. Pro paralleler Phase entscheiden Sie (oder der Co-Trainer auf dem eigenen Gerät), welcher
+            Stream coacht wird. Kurzwahl oben springt die betreffende Phase sofort auf einen Stream (z. B. zwischen Gruppen
+            wechseln).
+            {Object.keys(mergedPicks).length > 0 ? (
+              <span style={{ display: 'block', marginTop: '6px', color: 'var(--text3)', fontSize: '0.78rem' }}>
+                Aktuell festgelegt:{' '}
+                {Object.keys(mergedPicks)
+                  .map((pk) => {
+                    const po = parseInt(pk, 10)
+                    const so = mergedPicks[pk]
+                    const o = streamFocusOptions.find((x) => x.phaseOrder === po && x.streamOrder === so)
+                    return o?.label ?? `Phase ${po} · Stream ${so}`
+                  })
+                  .join(' · ')}
+              </span>
+            ) : null}
           </p>
         ) : null}
       </header>
 
       {outlineOpen && (
         <div className="card training-coach-outline" style={{ flexShrink: 0, marginBottom: '8px', padding: '10px 12px', maxHeight: 'min(28vh, 260px)', display: 'flex', flexDirection: 'column', minHeight: 0 }}>
-          <div style={{ fontSize: '0.75rem', color: 'var(--text3)', marginBottom: '6px', flexShrink: 0 }}>Ablauf · Antippen zum Springen</div>
-          <div style={{ display: 'flex', flexDirection: 'column', gap: '6px', overflowY: 'auto', minHeight: 0 }}>
-            {timeline.map((ent, ix) => {
-              const lbl = summarizeTimelineEntry(ent)
-              const ctx = ent.coachContext || ''
-              const active = coachDebriefPhase ? ix === timeline.length - 1 : ix === step
-              return (
-                <button
-                  key={`${itemStableKey(ent.item, ent.secOrder, ent.ii)}-${ix}`}
-                  type="button"
-                  className={`btn ${active ? 'btn-primary' : 'btn-secondary'}`}
+          <div style={{ fontSize: '0.75rem', color: 'var(--text3)', marginBottom: '6px', flexShrink: 0 }}>
+            Trainingsrahmen · nach Blöcken und Streams
+          </div>
+          <div style={{ display: 'flex', flexDirection: 'column', gap: '10px', overflowY: 'auto', minHeight: 0 }}>
+            {outlineGroups.map((grp) => (
+              <div key={grp.mergeKey} style={{ display: 'flex', flexDirection: 'column', gap: '6px' }}>
+                <div
                   style={{
-                    textAlign: 'left',
-                    justifyContent: 'flex-start',
-                    opacity: active ? 1 : 0.92,
-                    fontWeight: active ? 700 : 500
-                  }}
-                  onClick={() => {
-                    setCoachDebriefPhase(false)
-                    setStep(ix)
+                    fontSize: '0.72rem',
+                    fontWeight: 700,
+                    color: 'var(--accent-dark)',
+                    textTransform: 'uppercase',
+                    letterSpacing: '0.04em',
                   }}
                 >
-                  {ctx ? (
-                    <span style={{ opacity: 0.8, display: 'block', fontSize: '0.72rem', marginBottom: '2px' }}>
-                      {ctx.length > 42 ? `${ctx.slice(0, 40)}…` : ctx}
-                    </span>
-                  ) : null}
-                  <span>{lbl}</span>
-                </button>
-              )
-            })}
+                  {grp.heading}
+                  {grp.sub ? <span style={{ fontWeight: 600, color: 'var(--text3)', textTransform: 'none' }}> · {grp.sub}</span> : null}
+                </div>
+                <div style={{ display: 'flex', flexDirection: 'column', gap: '6px' }}>
+                  {grp.entries.map(({ ix, ent }) => {
+                    const lbl = summarizeTimelineEntry(ent)
+                    const ctx = ent.coachContext || ''
+                    const active = coachDebriefPhase ? ix === timeline.length - 1 : ix === step
+                    const rowKey =
+                      ent.entryKind === COACH_ENTRY_BRANCH_GATE
+                        ? `gate-${ix}`
+                        : `${itemStableKey(ent.item, ent.secOrder, ent.ii)}-${ix}`
+                    return (
+                      <button
+                        key={rowKey}
+                        type="button"
+                        className={`btn ${active ? 'btn-primary' : 'btn-secondary'}`}
+                        style={{
+                          textAlign: 'left',
+                          justifyContent: 'flex-start',
+                          opacity: active ? 1 : 0.92,
+                          fontWeight: active ? 700 : 500,
+                        }}
+                        onClick={() => {
+                          setCoachDebriefPhase(false)
+                          setStep(ix)
+                        }}
+                      >
+                        {ctx ? (
+                          <span style={{ opacity: 0.8, display: 'block', fontSize: '0.72rem', marginBottom: '2px' }}>
+                            {ctx.length > 42 ? `${ctx.slice(0, 40)}…` : ctx}
+                          </span>
+                        ) : null}
+                        <span>{lbl}</span>
+                      </button>
+                    )
+                  })}
+                </div>
+              </div>
+            ))}
           </div>
         </div>
       )}
@@ -680,7 +833,7 @@ export default function TrainingCoachPage() {
             </p>
             <div style={{ display: 'flex', flexDirection: 'column', gap: '10px', marginBottom: '12px' }}>
               {timeline
-                .filter((e) => e.item.item_type === 'exercise')
+                .filter((e) => e.item?.item_type === 'exercise')
                 .map((ent) => {
                   const k = itemStableKey(ent.item, ent.secOrder, ent.ii)
                   const val = deltas[k]?.actual_duration_min ?? ent.item.actual_duration_min ?? ''
@@ -765,7 +918,12 @@ export default function TrainingCoachPage() {
             <div style={{ fontSize: '0.72rem', fontWeight: 700, color: 'var(--accent-dark)', marginBottom: '6px' }}>
               Als Nächstes
             </div>
-            {nextEntry ? (
+            {atBranchGate ? (
+              <p style={{ margin: 0, fontSize: '0.88rem', color: 'var(--text2)', lineHeight: 1.45 }}>
+                Wählen Sie unten eine Gruppe. Danach zeigt der Coach fortlaufend nur die Übungen dieses Streams in dieser
+                parallelen Phase.
+              </p>
+            ) : nextEntry ? (
               <>
                 <p style={{ margin: '0', fontSize: '0.9rem', color: 'var(--text1)', lineHeight: 1.4 }}>
                   <strong>Nächste:</strong> {summarizeTimelineEntry(nextEntry)}
@@ -802,10 +960,70 @@ export default function TrainingCoachPage() {
             showJumpToTimerOwnerRow
             onJumpToTimerOwner={() => setStep(timerOwningStep ?? step)}
             timerOwnerLabelIndex={timerOwningStep ?? 0}
+            branchGateMode={atBranchGate}
           />
 
           <div className="training-coach-scroll">
-            {currentEntry?.item?.item_type === 'note' ? (
+            {atBranchGate && currentEntry?.branchMeta ? (
+              <div
+                className="card"
+                style={{
+                  padding: '16px 14px',
+                  marginBottom: '12px',
+                  borderRadius: '12px',
+                  borderLeft: '4px solid var(--accent)',
+                  background: 'var(--surface)',
+                }}
+              >
+                <div style={{ fontSize: '0.72rem', fontWeight: 700, color: 'var(--text3)', marginBottom: '8px' }}>
+                  Parallele Phase · Coaching-Zweig
+                </div>
+                <p style={{ fontSize: '1.02rem', fontWeight: 700, margin: '0 0 8px', color: 'var(--accent-dark)' }}>
+                  {currentEntry.branchMeta.phaseTitle != null && String(currentEntry.branchMeta.phaseTitle).trim()
+                    ? String(currentEntry.branchMeta.phaseTitle).trim()
+                    : `Phase ${currentEntry.branchMeta.phaseOrderIndex}`}
+                </p>
+                <p style={{ fontSize: '0.86rem', color: 'var(--text2)', margin: '0 0 14px', lineHeight: 1.45 }}>
+                  Welchen Stream coachen Sie jetzt? Jeder Trainer kann auf seinem Gerät eine andere Gruppe wählen. Sobald Sie
+                  wählen, folgen nacheinander die Übungen genau dieser Spalte (ohne Verschränkung mit den anderen Streams).
+                </p>
+                <div style={{ display: 'flex', flexDirection: 'column', gap: '10px' }}>
+                  {(currentEntry.branchMeta.streams || []).map((st) => {
+                    const hinted =
+                      streamChoiceHint?.phaseOrder === currentEntry.branchMeta.phaseOrderIndex &&
+                      streamChoiceHint?.streamOrder === st.streamOrder
+                    const label = st.streamTitle?.trim() ? String(st.streamTitle).trim() : `Gruppe ${st.streamOrder + 1}`
+                    return (
+                      <button
+                        key={st.printStreamId || `s-${st.streamOrder}`}
+                        type="button"
+                        className={hinted ? 'btn btn-primary' : 'btn btn-secondary'}
+                        style={{ textAlign: 'left', justifyContent: 'flex-start', padding: '12px 14px', fontWeight: 600 }}
+                        onClick={() => pickStreamForPhase(currentEntry.branchMeta.phaseOrderIndex, st.streamOrder)}
+                      >
+                        <span style={{ display: 'block' }}>{label}</span>
+                        <span
+                          style={{
+                            display: 'block',
+                            fontSize: '0.82rem',
+                            fontWeight: 500,
+                            opacity: 0.9,
+                            marginTop: '4px',
+                          }}
+                        >
+                          ca. {st.minutes} Min. (Üb.) · Antippen zum Fortfahren
+                        </span>
+                        {hinted ? (
+                          <span style={{ display: 'block', fontSize: '0.75rem', marginTop: '6px', opacity: 0.95 }}>
+                            Hinweis aus Planansicht — bei Bedarf andere Gruppe wählen.
+                          </span>
+                        ) : null}
+                      </button>
+                    )
+                  })}
+                </div>
+              </div>
+            ) : currentEntry?.item?.item_type === 'note' ? (
               <div className="card" style={{ padding: '16px 14px' }}>
                 <div style={{ fontSize: '0.74rem', color: 'var(--text3)', marginBottom: '8px' }}>
                   {currentEntry.coachContext || currentEntry.sec.title || 'Abschnitt'} · Coach-Notiz · Teil{' '}
@@ -907,7 +1125,7 @@ export default function TrainingCoachPage() {
                   </p>
                   <div style={{ display: 'flex', flexDirection: 'column', gap: '10px', marginBottom: '12px' }}>
                     {timeline
-                      .filter((e) => e.item.item_type === 'exercise')
+                      .filter((e) => e.item?.item_type === 'exercise')
                       .map((ent) => {
                         const k = itemStableKey(ent.item, ent.secOrder, ent.ii)
                         const val = deltas[k]?.actual_duration_min ?? ent.item.actual_duration_min ?? ''
@@ -980,6 +1198,7 @@ export default function TrainingCoachPage() {
             showJumpToTimerOwnerRow={false}
             onJumpToTimerOwner={() => setStep(timerOwningStep ?? step)}
             timerOwnerLabelIndex={timerOwningStep ?? 0}
+            branchGateMode={atBranchGate}
           />
         </>
       )}

frontend/src/pages/TrainingUnitRunPage.jsx

@@ -653,7 +653,7 @@ export default function TrainingUnitRunPage() {
                             </span>
                             <Link
                               className="no-print"
-                              to={`/planning/run/${unitId}/coach?po=${run.phaseOrderIndex}&so=${st.streamOrder}`}
+                              to={`/planning/run/${unitId}/coach?atBranch=${run.phaseOrderIndex}&preferSo=${st.streamOrder}`}
                               style={{
                                 fontSize: '0.78rem',
                                 fontWeight: 600,
@@ -663,7 +663,7 @@ export default function TrainingUnitRunPage() {
                                 whiteSpace: 'nowrap',
                               }}
                             >
-                              Coach · nur diese Gruppe
+                              Coach · Split-Punkt (Vorschlag)
                             </Link>
                           </div>
                           <div style={{ display: 'flex', flexDirection: 'column', gap: '1rem' }}>

frontend/src/utils/trainingPlanUtils.js

@@ -208,16 +208,141 @@ function coachContextLabelForSection(sec, sectionsList) {
   return `Parallel · ${pt} · ${st}`
 }
 
-/** Flache Reihenfolge für Coach-Timeline.
- * @param {object|null} coachFocus `{ phaseOrder, streamOrder }` = nur dieser Stream in dieser parallelen Phase; andere Split-Phasen weiterhin voll (alle Streams verschränkt). Null = Gesamtplan.*/
-export function flattenPlanTimeline(unit, coachFocus = null) {
+export const COACH_ENTRY_BRANCH_GATE = 'branch_gate'
+
+/** Normalisierte Stream-Wahl pro paralleler Phase (Phase-Index → Stream-Order). */
+export function normalizeCoachBranchPicks(raw) {
+  const out = {}
+  if (!raw || typeof raw !== 'object') return out
+  for (const [k, v] of Object.entries(raw)) {
+    const pk = parseInt(String(k), 10)
+    const sv = typeof v === 'number' ? v : parseInt(String(v), 10)
+    if (Number.isFinite(pk) && Number.isFinite(sv)) out[pk] = sv
+  }
+  return out
+}
+
+/**
+ * URL-/Dropdown-Fokus `coachFocus` in Pick-Map mergen (fest gewählter Stream für eine Phase).
+ * @param {object} branchPicks Roh-Picks (z. B. aus Session)
+ * @param {{ phaseOrder: number, streamOrder: number }|null} coachFocusUrl z. B. ?po=&so=
+ */
+export function mergeCoachBranchPicksWithUrlFocus(branchPicks, coachFocusUrl) {
+  const m = normalizeCoachBranchPicks(branchPicks)
+  if (
+    coachFocusUrl != null &&
+    Number.isFinite(coachFocusUrl.phaseOrder) &&
+    Number.isFinite(coachFocusUrl.streamOrder)
+  ) {
+    m[coachFocusUrl.phaseOrder] = coachFocusUrl.streamOrder
+  }
+  return m
+}
+
+/** Kurzstring für SessionStorage-Schlüssel (Sortierung stabil). */
+export function coachBranchPicksStepStorageSuffix(mergedPicks) {
+  const keys = Object.keys(mergedPicks)
+    .map((k) => parseInt(String(k), 10))
+    .filter((n) => Number.isFinite(n))
+    .sort((a, b) => a - b)
+  if (!keys.length) return 'full'
+  return keys.map((k) => `p${k}-s${mergedPicks[k]}`).join('_')
+}
+
+export function coachBranchPicksStorageKey(unitId) {
+  return `sj_coach_branches_${unitId}`
+}
+
+/**
+ * Index zum Springen: Co-Trainer-Link atBranch+preferSo — Gate falls noch offen, sonst erste Kachel im Stream.
+ */
+export function findCoachTimelineJumpIndexForPhase(timeline, phaseOrder, preferStreamOrder = null) {
+  const po = Number(phaseOrder)
+  if (!Number.isFinite(po) || !Array.isArray(timeline)) return -1
+  const hint = preferStreamOrder != null && Number.isFinite(Number(preferStreamOrder)) ? Number(preferStreamOrder) : null
+  if (hint != null) {
+    const ixStream = timeline.findIndex(
+      (e) =>
+        e.entryKind !== COACH_ENTRY_BRANCH_GATE &&
+        e.runMeta?.kind === 'parallel' &&
+        e.runMeta.phaseOrderIndex === po &&
+        e.runMeta.streamOrder === hint
+    )
+    if (ixStream >= 0) return ixStream
+  }
+  const ixGate = timeline.findIndex(
+    (e) => e.entryKind === COACH_ENTRY_BRANCH_GATE && e.branchMeta?.phaseOrderIndex === po
+  )
+  return ixGate
+}
+
+/** Gruppiert die flache Coach-Timeline für den Trainingsrahmen (Überschriften + Einträge). */
+export function coachOutlineGroupsFromTimeline(timeline) {
+  const groups = []
+  for (let ix = 0; ix < timeline.length; ix++) {
+    const ent = timeline[ix]
+    let mergeKey = `ix-${ix}`
+    let heading = 'Ablauf'
+    let sub = ''
+    if (ent.entryKind === COACH_ENTRY_BRANCH_GATE) {
+      const po = ent.branchMeta?.phaseOrderIndex ?? 0
+      mergeKey = `gate-${po}`
+      heading = 'Split · Gruppe wählen'
+      const pt = ent.branchMeta?.phaseTitle
+      sub =
+        pt != null && String(pt).trim()
+          ? String(pt).trim()
+          : `Parallele Phase ${po}`
+    } else {
+      const rm = ent.runMeta
+      if (rm?.kind === 'whole_group') {
+        mergeKey = `wg-${rm.phaseOrderIndex}`
+        const pl = ent.sec?.planLoc
+        const ptt = pl?.phaseTitle
+        heading = 'Ganzgruppe'
+        sub = ptt != null && String(ptt).trim() ? String(ptt).trim() : ''
+      } else if (rm?.kind === 'parallel' && rm.streamOrder != null) {
+        mergeKey = `par-${rm.phaseOrderIndex}-s${rm.streamOrder}`
+        const pl = ent.sec?.planLoc
+        const ptt = pl?.phaseTitle
+        const stt = pl?.streamTitle
+        const ptl = ptt != null && String(ptt).trim() ? String(ptt).trim() : `Phase ${rm.phaseOrderIndex}`
+        const stl = stt != null && String(stt).trim() ? String(stt).trim() : `Gruppe ${rm.streamOrder + 1}`
+        heading = `Parallel · ${ptl}`
+        sub = stl
+      } else if (rm?.kind === 'legacy') {
+        mergeKey = 'legacy'
+        heading = 'Ablauf'
+        sub = ''
+      } else {
+        mergeKey = `misc-${ix}`
+      }
+    }
+    const prev = groups[groups.length - 1]
+    if (!prev || prev.mergeKey !== mergeKey) {
+      groups.push({ mergeKey, heading, sub, entries: [{ ix, ent }] })
+    } else {
+      prev.entries.push({ ix, ent })
+    }
+  }
+  return groups
+}
+
+/**
+ * Flache Coach-Reihenfolge. Pro paralleler Phase ohne Eintrag in branchPicks: ein sichtbarer branch_gate,
+ * damit keine verschränkten Split-Übungen, bis eine Gruppe gewählt wurde.
+ * @param {object} unit
+ * @param {object} branchPicks z. B. { 0: 1 } = Phase 0 → Stream 1
+ */
+export function flattenPlanTimeline(unit, branchPicks = {}) {
   const sections = sectionsWithPlanLocForDisplay(unit)
   const model = buildPlanRunViewModelFromSections(sections)
   if (model.mode === 'empty') return []
 
+  const picks = normalizeCoachBranchPicks(branchPicks)
   const list = []
 
-  const pushSectionItems = (sec, coachCtx) => {
+  const pushSectionItems = (sec, coachCtx, runMeta) => {
     const si = Math.max(0, sections.indexOf(sec))
     const secOrder = sec.order_index ?? si
     sortedItems(sec).forEach((item, ii) => {
@@ -229,28 +354,53 @@ export function flattenPlanTimeline(unit, coachFocus = null) {
         sec,
         item,
         coachContext: coachCtx,
+        runMeta: runMeta || null,
       })
     })
   }
 
-  const f = coachFocus
   for (const run of model.runs) {
-    if (run.kind === 'legacy' || run.kind === 'whole_group') {
+    if (run.kind === 'legacy') {
+      const meta = { kind: 'legacy', phaseOrderIndex: 0, streamOrder: null }
       for (const sec of run.globalOrderSections) {
-        pushSectionItems(sec, coachContextLabelForSection(sec, sections))
+        pushSectionItems(sec, coachContextLabelForSection(sec, sections), meta)
+      }
+      continue
+    }
+    if (run.kind === 'whole_group') {
+      const meta = { kind: 'whole_group', phaseOrderIndex: run.phaseOrderIndex, streamOrder: null }
+      for (const sec of run.globalOrderSections) {
+        pushSectionItems(sec, coachContextLabelForSection(sec, sections), meta)
       }
       continue
     }
     if (run.kind === 'parallel') {
-      if (f == null || run.phaseOrderIndex !== f.phaseOrder) {
-        for (const sec of run.globalOrderSections) {
-          pushSectionItems(sec, coachContextLabelForSection(sec, sections))
-        }
+      const po = run.phaseOrderIndex
+      const chosen = picks[po]
+      const hasPick = chosen !== undefined && chosen !== null && Number.isFinite(Number(chosen))
+      if (!hasPick) {
+        list.push({
+          entryKind: COACH_ENTRY_BRANCH_GATE,
+          si: -1,
+          ii: -1,
+          secOrder: -1,
+          flatIndex: list.length,
+          sec: null,
+          item: null,
+          coachContext: '',
+          branchMeta: {
+            phaseOrderIndex: po,
+            phaseTitle: run.phaseTitle,
+            streams: run.streams || [],
+          },
+          runMeta: { kind: 'parallel', phaseOrderIndex: po, streamOrder: null },
+        })
       } else {
-        const st = run.streams?.find((x) => x.streamOrder === f.streamOrder)
+        const st = run.streams?.find((x) => x.streamOrder === Number(chosen))
+        const meta = { kind: 'parallel', phaseOrderIndex: po, streamOrder: Number(chosen) }
         if (st?.sections?.length) {
           for (const sec of st.sections) {
-            pushSectionItems(sec, coachContextLabelForSection(sec, sections))
+            pushSectionItems(sec, coachContextLabelForSection(sec, sections), meta)
           }
         }
       }
@@ -305,7 +455,15 @@ export function durationOverridesMapFromDeltas(unit, deltas) {
   return out
 }
 
-export function summarizeTimelineEntry({ item }) {
+export function summarizeTimelineEntry(ent) {
+  if (!ent) return ''
+  if (ent.entryKind === COACH_ENTRY_BRANCH_GATE) {
+    const t = ent.branchMeta?.phaseTitle != null && String(ent.branchMeta.phaseTitle).trim()
+      ? String(ent.branchMeta.phaseTitle).trim()
+      : ''
+    return t ? `Split wählen · ${t}` : 'Split · Gruppe wählen'
+  }
+  const { item } = ent
   if (!item) return ''
   if (item.item_type === 'note') {
     const t = String(item.note_body || '').trim()