diff --git a/app/cis.py b/app/cis.py
index 45621fa..de4db86 100644
--- a/app/cis.py
+++ b/app/cis.py
@@ -297,6 +297,19 @@ class CISClient:
                                matrikel=mail.split("@")[0] if "@" in mail else ""))
         return out
 
+    # ---------- Studien-Semester pro StG ----------
+    @lru_cache(maxsize=64)
+    def study_semesters(self, kz: str) -> list[int]:
+        """Von CIS bekannte Studien-Semester eines StG (z.B. [1..6] BSc, [1..4] MSc)."""
+        try:
+            r = self.s.post(f"{self.base}/private/lvplan/lvplan_autocomplete.php",
+                            data={"autocomplete": "getSemester", "stg_kz": kz}, timeout=30)
+            data = r.json()
+            vals = data.values() if isinstance(data, dict) else data
+            return sorted({int(x) for x in vals if str(x).strip().isdigit()})
+        except Exception:
+            return []
+
     # ---------- Verbände pro StG/Semester ----------
     def verbands_for(self, kz: str, sem: str) -> list[str]:
         fallback = ["V", "B", "G", "A", "C", "D", "E", "F"]
diff --git a/app/main.py b/app/main.py
index e866994..1647798 100644
--- a/app/main.py
+++ b/app/main.py
@@ -44,6 +44,23 @@ def _meta():
     return client.meta()
 
 
+def _study_sem_options(kz: str, semester_label: str) -> list[int]:
+    """Gültige Studien-Semester eines StG, gefiltert nach Plan-Semester
+    (Winter=ungerade, Sommer=gerade)."""
+    sems = client.study_semesters(kz)
+    if not sems:
+        code = next((s["code"] for s in _meta()["stgs"] if s["kz"] == kz), "") or ""
+        max_n = 4 if code[:1] in ("M", "L") else 6
+        sems = list(range(1, max_n + 1))
+    label = (semester_label or "").upper()
+    if label.startswith("WS"):
+        sems = [n for n in sems if n % 2 == 1]
+    elif label.startswith("SS"):
+        sems = [n for n in sems if n % 2 == 0]
+    sems = sorted(set(sems))
+    return sems or [1]
+
+
 @app.get("/", response_class=HTMLResponse)
 def home(request: Request):
     meta = _meta()
@@ -60,13 +77,16 @@ def _plan_common(request, kind, uid, kz, sem, ver, grp, semester, week="", tab="
     semester = semester or current_semester(meta["semesters"])
     s = next((x for x in meta["semesters"] if x["label"] == semester), meta["semesters"][0])
     person = None
+    sems: list[int] = []
     if kind == "student":
         uid = uid or OWN_UID
         person = client.person(uid)
         events = client.student_events(uid, s["begin"], s["ende"])
     else:
         kz = kz or "640"
-        sem = sem or "1"
+        sems = _study_sem_options(kz, semester)
+        if sem not in [str(n) for n in sems]:
+            sem = str(sems[0])
         ver = ver or "V"
         events = client.stg_events(kz, sem, ver, grp, s["begin"], s["ende"])
     # initial week: explicit param, today if inside semester, else first event week
@@ -93,6 +113,7 @@ def _plan_common(request, kind, uid, kz, sem, ver, grp, semester, week="", tab="
         "uid": uid or "",
         "kz": kz or "",
         "sem": sem or "",
+        "sems": sems,
         "ver": ver or "",
         "grp": grp or "",
         "stg": stg,
@@ -144,6 +165,9 @@ def liste(request: Request,
           sem: str = Query("1"),
           ver: str = Query("V")):
     meta = _meta()
+    sems = _study_sem_options(kz, current_semester(meta["semesters"]))
+    if sem not in [str(n) for n in sems]:
+        sem = str(sems[0])
     students = client.namensliste(kz, sem, ver)
     stg = next((x for x in meta["stgs"] if x["kz"] == kz), None)
     verbands = client.verbands_for(kz, sem)
@@ -155,6 +179,7 @@ def liste(request: Request,
         "meta": meta,
         "kz": kz,
         "sem": sem,
+        "sems": sems,
         "ver": ver,
         "verbands": verbands,
         "stg": stg,
@@ -214,6 +239,9 @@ def fotos_page(request: Request,
                sem: str = Query("1"),
                ver: str = Query("V")):
     meta = _meta()
+    sems = _study_sem_options(kz, current_semester(meta["semesters"]))
+    if sem not in [str(n) for n in sems]:
+        sem = str(sems[0])
     stg = next((x for x in meta["stgs"] if x["kz"] == kz), None)
     verbands = client.verbands_for(kz, sem)
     wall = _photo_wall(kz, sem, ver)
@@ -222,6 +250,7 @@ def fotos_page(request: Request,
         "meta": meta,
         "kz": kz,
         "sem": sem,
+        "sems": sems,
         "ver": ver,
         "verbands": verbands,
         "stg": stg,
@@ -248,32 +277,32 @@ def fotos_suche(request: Request,
                 sem: str = Form("1"),
                 ver: str = Form("V"),
                 file: UploadFile = File(...)):
+    meta = _meta()
+    sems = _study_sem_options(kz, current_semester(meta["semesters"]))
+    if sem not in [str(n) for n in sems]:
+        sem = str(sems[0])
+    base_ctx = {
+        "request": request,
+        "kz": kz, "sem": sem, "sems": sems, "ver": ver,
+        "results": [], "meta": meta,
+        "stg": next((x for x in meta["stgs"] if x["kz"] == kz), None),
+        "verbands": client.verbands_for(kz, sem),
+        "own_uid": OWN_UID,
+    }
     data = file.file.read()
     if not data:
-        return templates.TemplateResponse(request, "fotos_result.html", {
-            "request": request, "error": "Leere Datei hochgeladen.",
-            "kz": kz, "sem": sem, "ver": ver, "results": [], "meta": _meta(),
-            "stg": next((x for x in _meta()["stgs"] if x["kz"] == kz), None),
-            "verbands": client.verbands_for(kz, sem),
-            "own_uid": OWN_UID,
-        }, status_code=400)
+        return templates.TemplateResponse(request, "fotos_result.html",
+                                          {**base_ctx, "error": "Leere Datei hochgeladen."},
+                                          status_code=400)
     if len(data) > MAX_UPLOAD:
-        return templates.TemplateResponse(request, "fotos_result.html", {
-            "request": request, "error": "Datei zu groß (max. 8 MB).",
-            "kz": kz, "sem": sem, "ver": ver, "results": [], "meta": _meta(),
-            "stg": next((x for x in _meta()["stgs"] if x["kz"] == kz), None),
-            "verbands": client.verbands_for(kz, sem),
-            "own_uid": OWN_UID,
-        }, status_code=400)
+        return templates.TemplateResponse(request, "fotos_result.html",
+                                          {**base_ctx, "error": "Datei zu groß (max. 8 MB)."},
+                                          status_code=400)
     emb = engine.embed(data)
     if emb is None:
-        return templates.TemplateResponse(request, "fotos_result.html", {
-            "request": request, "error": "Kein Gesicht im hochgeladenen Bild gefunden.",
-            "kz": kz, "sem": sem, "ver": ver, "results": [], "meta": _meta(),
-            "stg": next((x for x in _meta()["stgs"] if x["kz"] == kz), None),
-            "verbands": client.verbands_for(kz, sem),
-            "own_uid": OWN_UID,
-        }, status_code=422)
+        return templates.TemplateResponse(request, "fotos_result.html",
+                                          {**base_ctx, "error": "Kein Gesicht im hochgeladenen Bild gefunden."},
+                                          status_code=422)
     wall = _photo_wall(kz, sem, ver)
     results = []
     t0 = time.time()
@@ -291,18 +320,12 @@ def fotos_suche(request: Request,
         results.append({**p, "sim": round(sim, 4),
                         "img": f"/fotos/img/{pid}"})
     results.sort(key=lambda r: r["sim"], reverse=True)
-    meta = _meta()
     return templates.TemplateResponse(request, "fotos_result.html", {
-        "request": request,
+        **base_ctx,
         "error": None,
         "took": round(time.time() - t0, 1),
         "query": {"kz": kz, "sem": sem, "ver": ver},
-        "kz": kz, "sem": sem, "ver": ver,
         "results": results[:30],
-        "meta": meta,
-        "stg": next((x for x in meta["stgs"] if x["kz"] == kz), None),
-        "verbands": client.verbands_for(kz, sem),
-        "own_uid": OWN_UID,
     })
 
 
diff --git a/app/static/app.js b/app/static/app.js
index 738a81b..e6b202d 100644
--- a/app/static/app.js
+++ b/app/static/app.js
@@ -380,7 +380,32 @@ function decodeMat() {
   box.classList.add("show");
 }
 
-/* ================= Verband-Selects dynamisch ================= */
+/* ================= Seminar- + Verband-Selects dynamisch ================= */
+async function reloadSemesters() {
+  const sel = $("#sem-select");
+  const stgSel = $("#stg-select");
+  if (!sel || !stgSel) return;
+  const kz = stgSel.value;
+  const planSem = (($('select[name="semester"]') || {}).value || "").toUpperCase();
+  try {
+    const r = await fetch(`/api/semesters_for_stg?kz=${encodeURIComponent(kz)}`);
+    if (!r.ok) throw new Error("bad status");
+    let data = await r.json();
+    let arr = (Array.isArray(data) ? data : Object.values(data))
+      .map(Number).filter(n => Number.isInteger(n) && n > 0);
+    if (planSem.startsWith("WS")) arr = arr.filter(n => n % 2 === 1);
+    else if (planSem.startsWith("SS")) arr = arr.filter(n => n % 2 === 0);
+    arr = [...new Set(arr)].sort((a, b) => a - b);
+    if (arr.length) {
+      const current = sel.value;
+      sel.innerHTML = arr.map(n =>
+        `<option value="${n}"${n === Number(current) ? " selected" : ""}>${n}</option>`).join("");
+      if (current && !arr.includes(Number(current))) sel.selectedIndex = 0;
+    }
+  } catch (e) { /* Keep static options */ }
+  reloadVerbands();
+}
+
 async function reloadVerbands() {
   const sel = $("#ver-select");
   if (!sel) return;
diff --git a/app/templates/fotos.html b/app/templates/fotos.html
index 3379dda..3a81995 100644
--- a/app/templates/fotos.html
+++ b/app/templates/fotos.html
@@ -19,7 +19,7 @@
     <div class="field">
       <label>Studien-Semester</label>
       <select name="sem">
-        {% for n in range(1, 9) %}
+        {% for n in sems %}
           <option value="{{ n }}" {{ 'selected' if (n | string) == sem }}>{{ n }}</option>
         {% endfor %}
       </select>
diff --git a/app/templates/fotos_result.html b/app/templates/fotos_result.html
index f8dc142..8e7828e 100644
--- a/app/templates/fotos_result.html
+++ b/app/templates/fotos_result.html
@@ -18,7 +18,7 @@
     <div class="field">
       <label>Studien-Semester</label>
       <select name="sem">
-        {% for n in range(1, 9) %}
+        {% for n in sems %}
           <option value="{{ n }}" {{ 'selected' if (n | string) == sem }}>{{ n }}</option>
         {% endfor %}
       </select>
diff --git a/app/templates/liste.html b/app/templates/liste.html
index a81fba9..42e6d22 100644
--- a/app/templates/liste.html
+++ b/app/templates/liste.html
@@ -18,11 +18,11 @@
     </div>
     <div class="field">
       <label>Studien-Semester</label>
-      <select name="sem" id="sem-select" onchange="reloadVerbands()">
-        {% for n in range(1, 9) %}
-          <option value="{{ n }}" {{ 'selected' if (n | string) == sem }}>{{ n }}</option>
-        {% endfor %}
-      </select>
+        <select name="sem" id="sem-select" onchange="reloadVerbands()">
+          {% for n in sems %}
+            <option value="{{ n }}" {{ 'selected' if (n | string) == sem }}>{{ n }}</option>
+          {% endfor %}
+        </select>
     </div>
     <div class="field">
       <label>Verband</label>
diff --git a/app/templates/plan.html b/app/templates/plan.html
index 90ec9a6..8d21ffc 100644
--- a/app/templates/plan.html
+++ b/app/templates/plan.html
@@ -35,7 +35,7 @@
     {% else %}
       <div class="field">
         <label>Studiengang</label>
-        <select name="kz" id="stg-select" required onchange="reloadVerbands()">
+          <select name="kz" id="stg-select" required onchange="reloadSemesters()">
           {% for s in meta.stgs %}
             <option value="{{ s.kz }}" {{ 'selected' if s.kz == kz }}>{{ s.code }} - {{ s.name }}</option>
           {% endfor %}
@@ -43,11 +43,11 @@
       </div>
       <div class="field">
         <label>Studien-Sem.</label>
-        <select name="sem" id="sem-select" onchange="reloadVerbands()">
-          {% for n in range(1, 9) %}
-            <option value="{{ n }}" {{ 'selected' if (n | string) == sem }}>{{ n }}</option>
-          {% endfor %}
-        </select>
+          <select name="sem" id="sem-select" onchange="reloadVerbands()">
+            {% for n in sems %}
+              <option value="{{ n }}" {{ 'selected' if (n | string) == sem }}>{{ n }}</option>
+            {% endfor %}
+          </select>
       </div>
       <div class="field">
         <label>Verband</label>