diff --git a/backend/version.py b/backend/version.py
index b3e05cf..9e7a6d1 100644
--- a/backend/version.py
+++ b/backend/version.py
@@ -1,6 +1,6 @@
 # Shinkan Jinkendo Version Information
 
-APP_VERSION = "0.8.128"
+APP_VERSION = "0.8.129"
 BUILD_DATE = "2026-05-12"
 DB_SCHEMA_VERSION = "20260514062"
 
@@ -36,6 +36,13 @@ MODULE_VERSIONS = {
 }
 
 CHANGELOG = [
+    {
+        "version": "0.8.129",
+        "date": "2026-05-13",
+        "changes": [
+            "Frontend Phase 3: TrainingPlanningTrainerAssignModal (Trainer zuweisen) aus Trainingsplanungsseite; Handler per useCallback.",
+        ],
+    },
     {
         "version": "0.8.128",
         "date": "2026-05-13",
diff --git a/frontend/src/components/planning/TrainingPlanningTrainerAssignModal.jsx b/frontend/src/components/planning/TrainingPlanningTrainerAssignModal.jsx
new file mode 100644
index 0000000..ac861fc
--- /dev/null
+++ b/frontend/src/components/planning/TrainingPlanningTrainerAssignModal.jsx
@@ -0,0 +1,155 @@
+import React from 'react'
+
+/**
+ * Modal: organisatorische Trainer-Zuweisung (Leitung + Co) für eine bestehende Einheit.
+ */
+export default function TrainingPlanningTrainerAssignModal({
+  open,
+  unit,
+  leadTrainerProfileId,
+  onLeadChange,
+  sessionAssistantsInherit,
+  onSessionAssistantsInheritChange,
+  sessionAssistantProfileIds,
+  onCoTrainerToggle,
+  clubDirectory,
+  coTrainerOptions,
+  saving,
+  onBackdropRequestClose,
+  onCancel,
+  onSave,
+}) {
+  if (!open || !unit) return null
+
+  return (
+    <div
+      data-testid="planning-trainer-assign-modal"
+      style={{
+        position: 'fixed',
+        top: 0,
+        left: 0,
+        right: 0,
+        bottom: 0,
+        background: 'rgba(0,0,0,0.5)',
+        display: 'flex',
+        alignItems: 'center',
+        justifyContent: 'center',
+        zIndex: 1020,
+        padding: '1rem',
+        overflowY: 'auto',
+      }}
+      role="presentation"
+      onClick={() => {
+        if (!saving) onBackdropRequestClose()
+      }}
+    >
+      <div
+        role="dialog"
+        aria-modal="true"
+        aria-labelledby="trainer-assign-modal-title"
+        onClick={(e) => e.stopPropagation()}
+        style={{
+          background: 'var(--surface)',
+          borderRadius: '12px',
+          padding: 'clamp(14px, 3vw, 1.75rem)',
+          maxWidth: 'min(460px, 100%)',
+          width: '100%',
+          maxHeight: '90vh',
+          overflowY: 'auto',
+          boxSizing: 'border-box',
+        }}
+      >
+        <h2 id="trainer-assign-modal-title" style={{ marginBottom: '0.5rem', fontSize: '1.1rem' }}>
+          Trainer zuweisen (organisatorisch)
+        </h2>
+        <p style={{ fontSize: '0.86rem', color: 'var(--text2)', marginBottom: '1rem', lineHeight: 1.45 }}>
+          {(unit.planned_date || '').toString().slice(0, 10)}
+          {unit.planned_time_start ? ` · ${String(unit.planned_time_start).slice(0, 5)}` : ''}
+          {(unit.group_name || '').trim() ? ` · ${(unit.group_name || '').trim()}` : null}
+        </p>
+        <div className="form-row">
+          <label className="form-label">Leitung (diese Einheit)</label>
+          <select
+            className="form-input"
+            value={leadTrainerProfileId}
+            onChange={(e) => onLeadChange(e.target.value)}
+            disabled={saving}
+          >
+            <option value="">Standard (Haupttrainer der Gruppe)</option>
+            {(clubDirectory || []).map((m) => {
+              const idStr = String(m.id)
+              return (
+                <option key={idStr} value={idStr}>
+                  {(m.name || '').trim() || m.email || `Profil ${m.id}`}
+                </option>
+              )
+            })}
+          </select>
+        </div>
+        <div className="form-row" style={{ marginTop: '0.85rem' }}>
+          <label style={{ display: 'flex', alignItems: 'center', gap: '8px', cursor: 'pointer' }}>
+            <input
+              type="checkbox"
+              checked={sessionAssistantsInherit}
+              disabled={saving}
+              onChange={(e) => onSessionAssistantsInheritChange(e.target.checked)}
+            />
+            <span style={{ fontSize: '0.9rem', color: 'var(--text1)' }}>Co-Trainer wie in der Trainingsgruppe</span>
+          </label>
+        </div>
+        {!sessionAssistantsInherit ? (
+          <div style={{ marginTop: '10px', maxHeight: '180px', overflowY: 'auto' }}>
+            {coTrainerOptions.map((m) => {
+              const mid = typeof m.id === 'number' ? m.id : parseInt(String(m.id), 10)
+              const labelText = `${(m.name || '').trim() || m.email || `Profil ${mid}`}`
+              const isOn = Number.isFinite(mid) && sessionAssistantProfileIds.includes(mid)
+              return (
+                <label
+                  key={`assign-co-${mid}`}
+                  style={{
+                    display: 'flex',
+                    alignItems: 'center',
+                    gap: '8px',
+                    fontSize: '0.875rem',
+                    marginBottom: '6px',
+                    cursor: saving ? 'default' : 'pointer',
+                    color: 'var(--text1)',
+                  }}
+                >
+                  <input
+                    type="checkbox"
+                    checked={isOn}
+                    disabled={saving}
+                    onChange={() => onCoTrainerToggle(mid)}
+                  />
+                  <span>{labelText}</span>
+                </label>
+              )
+            })}
+          </div>
+        ) : null}
+        {!clubDirectory.length ? (
+          <p style={{ marginTop: '10px', fontSize: '0.82rem', color: 'var(--text3)' }}>
+            Mitgliederverzeichnis konnte nicht geladen werden.
+          </p>
+        ) : null}
+        <div
+          style={{
+            display: 'flex',
+            gap: '0.65rem',
+            flexWrap: 'wrap',
+            justifyContent: 'flex-end',
+            marginTop: '1.25rem',
+          }}
+        >
+          <button type="button" className="btn btn-secondary" disabled={saving} onClick={onCancel}>
+            Abbrechen
+          </button>
+          <button type="button" className="btn btn-primary" disabled={saving} onClick={onSave}>
+            {saving ? 'Speichern …' : 'Speichern'}
+          </button>
+        </div>
+      </div>
+    </div>
+  )
+}
diff --git a/frontend/src/pages/TrainingPlanningPage.jsx b/frontend/src/pages/TrainingPlanningPage.jsx
index f491942..2de2a15 100644
--- a/frontend/src/pages/TrainingPlanningPage.jsx
+++ b/frontend/src/pages/TrainingPlanningPage.jsx
@@ -11,6 +11,7 @@ import TrainingPlanExerciseVisibilityPanel from '../components/TrainingPlanExerc
 import PageSectionNav from '../components/PageSectionNav'
 import TrainingPlanningFrameworkImportModal from '../components/planning/TrainingPlanningFrameworkImportModal'
 import TrainingPlanningModuleApplyModal from '../components/planning/TrainingPlanningModuleApplyModal'
+import TrainingPlanningTrainerAssignModal from '../components/planning/TrainingPlanningTrainerAssignModal'
 import {
   defaultSection,
   normalizeUnitToForm,
@@ -912,6 +913,42 @@ function TrainingPlanningPage() {
     }
   }
 
+  const handleAssignLeadSelectChange = useCallback((v) => {
+    setAssignDraft((prev) => {
+      const exclude = []
+      const tr = String(v || '').trim()
+      if (tr !== '') {
+        const n = parseInt(tr, 10)
+        if (Number.isFinite(n)) exclude.push(n)
+      } else if (prev.unit?.effective_lead_trainer_profile_id != null) {
+        const ef = Number(prev.unit.effective_lead_trainer_profile_id)
+        if (Number.isFinite(ef)) exclude.push(ef)
+      }
+      const exSet = new Set(exclude)
+      const co = exclude.length
+        ? prev.session_assistant_profile_ids.filter((x) => !exSet.has(x))
+        : prev.session_assistant_profile_ids
+      return { ...prev, lead_trainer_profile_id: v, session_assistant_profile_ids: co }
+    })
+  }, [])
+
+  const handleAssignAssistantsInheritChange = useCallback((checked) => {
+    setAssignDraft((prev) => ({
+      ...prev,
+      session_assistants_inherit: checked,
+    }))
+  }, [])
+
+  const handleAssignCoTrainerToggle = useCallback((mid) => {
+    setAssignDraft((prev) => {
+      const was = prev.session_assistant_profile_ids.includes(mid)
+      const nextIds = was
+        ? prev.session_assistant_profile_ids.filter((x) => x !== mid)
+        : [...prev.session_assistant_profile_ids, mid].sort((a, b) => a - b)
+      return { ...prev, session_assistant_profile_ids: nextIds }
+    })
+  }, [])
+
   const handleDelete = async (unit) => {
     if (!confirm(`Trainingseinheit vom ${unit.planned_date} wirklich löschen?`)) return
     try {
@@ -1821,178 +1858,24 @@ function TrainingPlanningPage() {
           </div>
         )}
 
-        {assignModalOpen && assignDraft.unit ? (
-          <div
-            style={{
-              position: 'fixed',
-              top: 0,
-              left: 0,
-              right: 0,
-              bottom: 0,
-              background: 'rgba(0,0,0,0.5)',
-              display: 'flex',
-              alignItems: 'center',
-              justifyContent: 'center',
-              zIndex: 1020,
-              padding: '1rem',
-              overflowY: 'auto',
-            }}
-            role="presentation"
-            onClick={() => {
-              if (!assignSaving) setAssignModalOpen(false)
-            }}
-          >
-            <div
-              role="dialog"
-              aria-modal="true"
-              aria-labelledby="trainer-assign-modal-title"
-              onClick={(e) => e.stopPropagation()}
-              style={{
-                background: 'var(--surface)',
-                borderRadius: '12px',
-                padding: 'clamp(14px, 3vw, 1.75rem)',
-                maxWidth: 'min(460px, 100%)',
-                width: '100%',
-                maxHeight: '90vh',
-                overflowY: 'auto',
-                boxSizing: 'border-box',
-              }}
-            >
-              <h2 id="trainer-assign-modal-title" style={{ marginBottom: '0.5rem', fontSize: '1.1rem' }}>
-                Trainer zuweisen (organisatorisch)
-              </h2>
-              <p style={{ fontSize: '0.86rem', color: 'var(--text2)', marginBottom: '1rem', lineHeight: 1.45 }}>
-                {(assignDraft.unit.planned_date || '').toString().slice(0, 10)}
-                {assignDraft.unit.planned_time_start
-                  ? ` · ${String(assignDraft.unit.planned_time_start).slice(0, 5)}`
-                  : ''}
-                {(assignDraft.unit.group_name || '').trim()
-                  ? ` · ${(assignDraft.unit.group_name || '').trim()}`
-                  : null}
-              </p>
-              <div className="form-row">
-                <label className="form-label">Leitung (diese Einheit)</label>
-                <select
-                  className="form-input"
-                  value={assignDraft.lead_trainer_profile_id}
-                  onChange={(e) => {
-                    const v = e.target.value
-                    setAssignDraft((prev) => {
-                      const exclude = []
-                      const tr = String(v || '').trim()
-                      if (tr !== '') {
-                        const n = parseInt(tr, 10)
-                        if (Number.isFinite(n)) exclude.push(n)
-                      } else if (prev.unit?.effective_lead_trainer_profile_id != null) {
-                        const ef = Number(prev.unit.effective_lead_trainer_profile_id)
-                        if (Number.isFinite(ef)) exclude.push(ef)
-                      }
-                      const exSet = new Set(exclude)
-                      const co = exclude.length
-                        ? prev.session_assistant_profile_ids.filter((x) => !exSet.has(x))
-                        : prev.session_assistant_profile_ids
-                      return { ...prev, lead_trainer_profile_id: v, session_assistant_profile_ids: co }
-                    })
-                  }}
-                  disabled={assignSaving}
-                >
-                  <option value="">Standard (Haupttrainer der Gruppe)</option>
-                  {clubDirectory.map((m) => {
-                    const idStr = String(m.id)
-                    return (
-                      <option key={idStr} value={idStr}>
-                        {(m.name || '').trim() || m.email || `Profil ${m.id}`}
-                      </option>
-                    )
-                  })}
-                </select>
-              </div>
-              <div className="form-row" style={{ marginTop: '0.85rem' }}>
-                <label style={{ display: 'flex', alignItems: 'center', gap: '8px', cursor: 'pointer' }}>
-                  <input
-                    type="checkbox"
-                    checked={assignDraft.session_assistants_inherit}
-                    disabled={assignSaving}
-                    onChange={(e) =>
-                      setAssignDraft((prev) => ({
-                        ...prev,
-                        session_assistants_inherit: e.target.checked,
-                      }))
-                    }
-                  />
-                  <span style={{ fontSize: '0.9rem', color: 'var(--text1)' }}>
-                    Co-Trainer wie in der Trainingsgruppe
-                  </span>
-                </label>
-              </div>
-              {!assignDraft.session_assistants_inherit ? (
-                <div style={{ marginTop: '10px', maxHeight: '180px', overflowY: 'auto' }}>
-                  {clubDirectoryForAssignCo.map((m) => {
-                    const mid = typeof m.id === 'number' ? m.id : parseInt(String(m.id), 10)
-                    const labelText = `${(m.name || '').trim() || m.email || `Profil ${mid}`}`
-                    const isOn = Number.isFinite(mid) && assignDraft.session_assistant_profile_ids.includes(mid)
-                    return (
-                      <label
-                        key={`assign-co-${mid}`}
-                        style={{
-                          display: 'flex',
-                          alignItems: 'center',
-                          gap: '8px',
-                          fontSize: '0.875rem',
-                          marginBottom: '6px',
-                          cursor: assignSaving ? 'default' : 'pointer',
-                          color: 'var(--text1)',
-                        }}
-                      >
-                        <input
-                          type="checkbox"
-                          checked={isOn}
-                          disabled={assignSaving}
-                          onChange={() => {
-                            setAssignDraft((prev) => {
-                              const was = prev.session_assistant_profile_ids.includes(mid)
-                              const nextIds = was
-                                ? prev.session_assistant_profile_ids.filter((x) => x !== mid)
-                                : [...prev.session_assistant_profile_ids, mid].sort((a, b) => a - b)
-                              return { ...prev, session_assistant_profile_ids: nextIds }
-                            })
-                          }}
-                        />
-                        <span>{labelText}</span>
-                      </label>
-                    )
-                  })}
-                </div>
-              ) : null}
-              {!clubDirectory.length ? (
-                <p style={{ marginTop: '10px', fontSize: '0.82rem', color: 'var(--text3)' }}>
-                  Mitgliederverzeichnis konnte nicht geladen werden.
-                </p>
-              ) : null}
-              <div
-                style={{
-                  display: 'flex',
-                  gap: '0.65rem',
-                  flexWrap: 'wrap',
-                  justifyContent: 'flex-end',
-                  marginTop: '1.25rem',
-                }}
-              >
-                <button
-                  type="button"
-                  className="btn btn-secondary"
-                  disabled={assignSaving}
-                  onClick={() => setAssignModalOpen(false)}
-                >
-                  Abbrechen
-                </button>
-                <button type="button" className="btn btn-primary" disabled={assignSaving} onClick={saveTrainerAssignModal}>
-                  {assignSaving ? 'Speichern …' : 'Speichern'}
-                </button>
-              </div>
-            </div>
-          </div>
-        ) : null}
+        <TrainingPlanningTrainerAssignModal
+          open={assignModalOpen && !!assignDraft.unit}
+          unit={assignDraft.unit}
+          leadTrainerProfileId={assignDraft.lead_trainer_profile_id}
+          onLeadChange={handleAssignLeadSelectChange}
+          sessionAssistantsInherit={assignDraft.session_assistants_inherit}
+          onSessionAssistantsInheritChange={handleAssignAssistantsInheritChange}
+          sessionAssistantProfileIds={assignDraft.session_assistant_profile_ids}
+          onCoTrainerToggle={handleAssignCoTrainerToggle}
+          clubDirectory={clubDirectory}
+          coTrainerOptions={clubDirectoryForAssignCo}
+          saving={assignSaving}
+          onBackdropRequestClose={() => {
+            if (!assignSaving) setAssignModalOpen(false)
+          }}
+          onCancel={() => setAssignModalOpen(false)}
+          onSave={saveTrainerAssignModal}
+        />
 
         <TrainingPlanningModuleApplyModal
           open={moduleApplyOpen}