diff --git a/app.py b/app.py
index 3e3b8e5..6a92774 100644
--- a/app.py
+++ b/app.py
@@ -36,6 +36,9 @@ LOGGER = logging.getLogger("engin.app")
 BASE_DIR = Path(__file__).resolve().parent
 MODEL_VERSION = "engin-2026.08.25-1"
 MODEL_ARTIFACT_DIR = BASE_DIR / "artifacts" / MODEL_VERSION
+VIEW_OVERVIEW = "Przegląd"
+VIEW_DETAIL = "Szczegóły cylindra"
+VIEW_MODEL = "Model"
 
 
 @dataclass(frozen=True)
@@ -115,7 +118,7 @@ def _render_header(live_inference: bool) -> None:
           <div>
             <div class="eyebrow">AESTEEL · DIESEL INJECTION DIAGNOSTICS</div>
             <h1>ENGIN Diagnostic Console</h1>
-            <p>Akustyczna diagnostyka każdego cylindra — typ usterki, nasilenie i uzasadnienie.</p>
+            <p>Diagnoza cylindra, nasilenie i następny krok.</p>
           </div>
           <div class="runtime-badge">● {mode}<br><span>CPU · LEAKAGE-SAFE</span></div>
         </div>
@@ -138,11 +141,12 @@ def _render_summary(summary) -> None:
     )
 
 
-def _select_cylinder(session_key: str, cylinder: int) -> None:
+def _select_cylinder(session_key: str, view_key: str, cylinder: int) -> None:
     st.session_state[session_key] = cylinder
+    st.session_state[view_key] = VIEW_DETAIL
 
 
-def _render_cylinder_grid(analysis, session_key: str) -> None:
+def _render_cylinder_grid(analysis, session_key: str, view_key: str) -> None:
     st.markdown("### Mapa cylindrów")
     columns = st.columns(4)
     selected_cylinder = int(st.session_state[session_key])
@@ -162,7 +166,7 @@ def _render_cylinder_grid(analysis, session_key: str) -> None:
                 width="stretch",
                 type="primary" if cylinder == selected_cylinder else "secondary",
                 on_click=_select_cylinder,
-                args=(session_key, cylinder),
+                args=(session_key, view_key, cylinder),
             )
 
 
@@ -184,10 +188,14 @@ def _render_engine_overview(analysis) -> None:
             width="stretch",
             height=315,
         )
-        st.caption("Kolejność: severity, odchylenie widma, następnie score modelu. Score nie jest skalibrowanym prawdopodobieństwem.")
+        st.caption("Priorytet: nasilenie → odchylenie → score modelu.")
 
 
-def _render_cylinder_detail(analysis, cylinder: int) -> None:
+def _render_cylinder_detail(
+    analysis,
+    cylinder: int,
+    comparison_cylinders: list[int],
+) -> None:
     explanation = explain_cylinder(analysis, cylinder)
     row = analysis.diagnostics[analysis.diagnostics["cylinder"].eq(cylinder)].iloc[0]
     color = LABEL_COLORS[explanation.label]
@@ -209,48 +217,47 @@ def _render_cylinder_detail(analysis, cylinder: int) -> None:
         """,
         unsafe_allow_html=True,
     )
-    spectrum_col, deviation_col = st.columns([1.25, 1.0], gap="large")
-    with spectrum_col:
-        st.plotly_chart(
-            cylinder_spectrum(analysis, cylinder),
-            width="stretch",
-            key=f"spectrum_{analysis.engine_id}_{cylinder}",
-        )
-    with deviation_col:
-        st.plotly_chart(
-            deviation_chart(analysis, cylinder),
-            width="stretch",
-            key=f"deviation_{analysis.engine_id}_{cylinder}",
-        )
+    st.markdown("#### Widma porównawcze")
+    st.plotly_chart(
+        cylinder_spectrum(analysis, cylinder, comparison_cylinders),
+        width="stretch",
+        key=(
+            f"spectrum_{analysis.engine_id}_"
+            + "_".join(str(value) for value in comparison_cylinders)
+        ),
+    )
+
+    st.markdown("#### Odchylenie cylindra głównego")
+    st.plotly_chart(
+        deviation_chart(analysis, cylinder),
+        width="stretch",
+        key=f"deviation_{analysis.engine_id}_{cylinder}",
+    )
 
     why, next_step = st.columns(2, gap="large")
     with why:
-        st.markdown("#### Dlaczego taka diagnoza?")
+        st.markdown("#### Uzasadnienie")
         st.write(explanation.reason)
-        frequencies = " · ".join(f"{value} kHz" for value in explanation.top_frequencies)
-        st.markdown(f"**Najbardziej anomalne pasma:** `{frequencies}`")
     with next_step:
-        st.markdown("#### Rekomendowany następny krok")
+        st.markdown("#### Następny krok")
         st.write(explanation.recommendation)
-        source_label = "Reguła OOD" if explanation.decision_source == "ood_override" else "Klasyfikator spektralny"
-        st.caption(f"Źródło decyzji: {source_label}")
-        st.caption("Score modelu służy do porównania predykcji; nie jest kalibrowanym prawdopodobieństwem awarii.")
+        source_label = (
+            "Reguła OOD"
+            if explanation.decision_source == "ood_override"
+            else "Klasyfikator spektralny"
+        )
+        st.caption(f"Źródło: {source_label} · score nie jest prawdopodobieństwem.")
 
 
 def _render_technical(result: DiagnosisResult) -> None:
-    st.markdown("### Kontrola jakości i architektura")
+    st.markdown("### Walidacja i model")
     c1, c2, c3, c4 = st.columns(4)
     c1.metric("Grouped Macro F1", "0.981")
     c2.metric("Severity accuracy", "0.930")
     c3.metric("Walidacyjne ML", "33.65 / 40")
-    c4.metric("Bramka jakości", "CI GREEN")
-    st.markdown(
-        """
-        - **Zero leakage:** każdy fold zawiera kompletne, wcześniej niewidziane silniki.
-        - **Odporność na braki:** wynik sprawdzony przy dokładnie 5% zamaskowanych komórek widma.
-        - **CPU-first:** Logistic Regression + Extra Trees, bez GPU i z deterministycznymi seedami.
-        - **Explainability:** każda diagnoza korzysta z referencji pozostałych cylindrów tego samego silnika.
-        """
+    c4.metric("Testy", "38 / 38")
+    st.caption(
+        "Grouped CV po engine_id · 5 seedów · Macro F1 przy 5% braków: 0.983 · CPU."
     )
     with st.expander("Pokaż dane diagnostyczne"):
         st.dataframe(result.diagnostics, width="stretch", hide_index=True)
@@ -277,7 +284,7 @@ def render_app(dependencies: AppDependencies | None = None) -> None:
         payload: bytes | None
         if source == "Dane demonstracyjne":
             payload = deps.demo_payload
-            st.success("Załadowano bezpieczny zestaw demonstracyjny")
+            st.success("Demo załadowane")
         else:
             uploaded = st.file_uploader("Plik pomiarowy CSV", type=["csv"])
             payload = uploaded.getvalue() if uploaded is not None else None
@@ -335,22 +342,55 @@ def render_app(dependencies: AppDependencies | None = None) -> None:
     available = analysis.measurements["cylinder"].astype(int).tolist()
     if session_key not in st.session_state or st.session_state[session_key] not in available:
         st.session_state[session_key] = summary.top_cylinder
-    _render_cylinder_grid(analysis, session_key)
 
-    overview_tab, detail_tab, technical_tab = st.tabs(
-        ["Przegląd silnika", "Szczegóły cylindra", "Walidacja i model"]
+    view_key = f"active_view_{analysis.engine_id}"
+    if view_key not in st.session_state:
+        st.session_state[view_key] = VIEW_OVERVIEW
+    view = st.segmented_control(
+        "Widok",
+        [VIEW_OVERVIEW, VIEW_DETAIL, VIEW_MODEL],
+        required=True,
+        key=view_key,
+        label_visibility="collapsed",
+        width="stretch",
     )
-    with overview_tab:
+
+    if view == VIEW_OVERVIEW:
+        _render_cylinder_grid(analysis, session_key, view_key)
         _render_engine_overview(analysis)
-    with detail_tab:
-        selected_from_box = st.selectbox(
-            "Cylinder do analizy",
-            available,
-            format_func=lambda value: f"Cylinder {value:02d}",
-            key=session_key,
+    elif view == VIEW_DETAIL:
+        selector_col, comparison_col = st.columns([1.0, 2.0], gap="large")
+        with selector_col:
+            selected_from_box = st.selectbox(
+                "Cylinder główny",
+                available,
+                format_func=lambda value: f"Cylinder {value:02d}",
+                key=session_key,
+            )
+        comparison_options = [
+            cylinder for cylinder in available if cylinder != selected_from_box
+        ]
+        with comparison_col:
+            additional_cylinders = st.multiselect(
+                "Porównaj z cylindrami",
+                comparison_options,
+                max_selections=3,
+                format_func=lambda value: f"Cylinder {value:02d}",
+                key=(
+                    f"comparison_{analysis.engine_id}_{int(selected_from_box)}"
+                ),
+                help="Cylinder główny jest zawsze pokazany; można dodać trzy kolejne.",
+            )
+        comparison_cylinders = [
+            int(selected_from_box),
+            *(int(value) for value in additional_cylinders),
+        ]
+        _render_cylinder_detail(
+            analysis,
+            int(selected_from_box),
+            comparison_cylinders,
         )
-        _render_cylinder_detail(analysis, int(selected_from_box))
-    with technical_tab:
+    elif view == VIEW_MODEL:
         _render_technical(result)
 
 
diff --git a/assets/app.css b/assets/app.css
index 09ca6a4..4307f41 100644
--- a/assets/app.css
+++ b/assets/app.css
@@ -64,9 +64,9 @@
 
 .diagnosis-card {
   --diagnosis-color: var(--cyan);
-  display: flex;
+  display: grid;
+  grid-template-columns: minmax(220px, .8fr) minmax(0, 1.6fr);
   align-items: center;
-  justify-content: space-between;
   gap: 2rem;
   padding: 1rem 1.25rem;
   margin: .5rem 0 1rem;
@@ -77,7 +77,11 @@
 .diagnosis-card h2 { margin: .08rem 0; color: var(--text); }
 .diagnosis-card p { margin: 0; color: var(--muted); }
 .diagnosis-kicker { color: var(--diagnosis-color); font: 800 .68rem ui-monospace, monospace; letter-spacing: .12em; }
-.diagnosis-metrics { display: flex; gap: 2rem; }
+.diagnosis-metrics {
+  display: grid;
+  grid-template-columns: repeat(3, minmax(110px, 1fr));
+  gap: 1rem;
+}
 .diagnosis-metrics strong { display: block; margin-top: .2rem; color: var(--text); font-size: 1.05rem; }
 
 [data-testid="stButton"] button {
@@ -92,16 +96,18 @@
 [data-testid="stButton"] button[kind="primary"] { border-color: var(--cyan); background: rgba(40, 183, 217, .13); }
 
 [data-testid="stMetric"] { padding: .7rem; border: 1px solid var(--line); background: var(--panel); }
-[data-testid="stDataFrame"], [data-testid="stPlotlyChart"] { border: 1px solid var(--line); }
+[data-testid="stDataFrame"], [data-testid="stPlotlyChart"] { border: 1px solid var(--line); overflow: hidden; }
 
-@media (max-width: 900px) {
-  .product-header, .diagnosis-card { flex-direction: column; }
+@media (max-width: 1000px) {
+  .product-header { flex-direction: column; }
+  .diagnosis-card { grid-template-columns: 1fr; }
   .runtime-badge { width: 100%; }
   .status-strip { grid-template-columns: repeat(2, 1fr); }
-  .diagnosis-metrics { width: 100%; flex-wrap: wrap; gap: 1rem 1.6rem; }
+  .diagnosis-metrics { width: 100%; }
 }
 
 @media (max-width: 560px) {
   .status-strip { grid-template-columns: 1fr; }
   .status-strip > div { border-right: 0; border-bottom: 1px solid var(--line); }
+  .diagnosis-metrics { grid-template-columns: 1fr; }
 }
diff --git a/docs/DEMO_SCENARIO.md b/docs/DEMO_SCENARIO.md
index a0fcebc..64b14d8 100644
--- a/docs/DEMO_SCENARIO.md
+++ b/docs/DEMO_SCENARIO.md
@@ -41,4 +41,4 @@ Zamknięcie: „ENGIN daje trzy rzeczy naraz: konkursowo skuteczny model, weryfi
 - Jeśli nie ma internetu: aplikacja nie potrzebuje internetu.
 - Jeśli model nie wystartuje: automatycznie działa fallback na zapisanych predykcjach demo.
 - Jeśli brakuje czasu: pokaż ekran główny, jeden cylinder i metryki — około 90 sekund.
-- Przed wystąpieniem uruchom `python -m unittest discover -v` i zachowaj terminal z wynikiem 32/32.
+- Przed wystąpieniem uruchom `python -m unittest discover -v` i zachowaj terminal z wynikiem 38/38.
diff --git a/engin/charts.py b/engin/charts.py
index d802457..ee4fb98 100644
--- a/engin/charts.py
+++ b/engin/charts.py
@@ -2,6 +2,8 @@
 
 from __future__ import annotations
 
+from collections.abc import Sequence
+
 import numpy as np
 import plotly.graph_objects as go
 
@@ -12,12 +14,19 @@ PLOT_BG = "#101820"
 GRID = "rgba(148, 163, 184, 0.14)"
 TEXT = "#dce8ee"
 MUTED = "#8fa6b2"
+COMPARISON_COLORS = ("#28b7d9", "#f5a524", "#38d996", "#d56cff", "#2f78ed")
 
 
-def _base_layout(fig: go.Figure, *, height: int) -> go.Figure:
+def _base_layout(
+    fig: go.Figure,
+    *,
+    height: int,
+    margin_top: int = 42,
+    margin_bottom: int = 28,
+) -> go.Figure:
     fig.update_layout(
         height=height,
-        margin=dict(l=24, r=24, t=42, b=28),
+        margin=dict(l=24, r=24, t=margin_top, b=margin_bottom),
         paper_bgcolor="rgba(0,0,0,0)",
         plot_bgcolor=PLOT_BG,
         font=dict(color=TEXT, family="Inter, system-ui, sans-serif"),
@@ -48,19 +57,33 @@ def engine_heatmap(analysis: EngineAnalysis) -> go.Figure:
             hovertemplate="Cylinder %{y}<br>%{x} kHz<br>Odchylenie %{z:.1f} mV<extra></extra>",
         )
     )
-    fig.update_layout(title="Engine Diagnostic Fingerprint")
+    fig.update_layout(title="Mapa odchyleń")
     fig.update_yaxes(autorange="reversed", title="Cylinder")
     fig.update_xaxes(title="Częstotliwość [kHz]", dtick=2)
     return _base_layout(fig, height=420)
 
 
-def cylinder_spectrum(analysis: EngineAnalysis, cylinder: int) -> go.Figure:
+def _cylinder_position(analysis: EngineAnalysis, cylinder: int) -> int:
     positions = np.flatnonzero(analysis.measurements["cylinder"].to_numpy() == cylinder)
     if len(positions) != 1:
         raise KeyError(f"Unknown cylinder={cylinder}")
-    position = int(positions[0])
+    return int(positions[0])
+
+
+def cylinder_spectrum(
+    analysis: EngineAnalysis,
+    cylinder: int,
+    comparison_cylinders: Sequence[int] | None = None,
+) -> go.Figure:
+    selected = list(
+        dict.fromkeys([cylinder, *(comparison_cylinders or ())])
+    )
+    if len(selected) > 4:
+        raise ValueError("At most four cylinders can be compared.")
+
+    position = _cylinder_position(analysis, cylinder)
     row = analysis.diagnostics.iloc[position]
-    color = LABEL_COLORS[str(row["label"])]
+    primary_color = LABEL_COLORS[str(row["label"])]
     frequency = np.arange(len(FREQ_COLS))
     fig = go.Figure()
     fig.add_trace(
@@ -68,20 +91,33 @@ def cylinder_spectrum(analysis: EngineAnalysis, cylinder: int) -> go.Figure:
             x=frequency,
             y=analysis.reference[position],
             mode="lines",
-            name="Mediana pozostałych cylindrów",
+            name=f"Referencja C{cylinder:02d}",
             line=dict(color="#7f95a1", width=2, dash="dash"),
         )
     )
-    fig.add_trace(
-        go.Scatter(
-            x=frequency,
-            y=analysis.spectra[position],
-            mode="lines+markers",
-            name=f"Cylinder {cylinder}",
-            line=dict(color=color, width=3),
-            marker=dict(size=6),
-        )
+
+    extra_colors = iter(
+        color
+        for color in COMPARISON_COLORS
+        if color.lower() != primary_color.lower()
     )
+    for selected_cylinder in selected:
+        selected_position = _cylinder_position(analysis, selected_cylinder)
+        color = primary_color if selected_cylinder == cylinder else next(extra_colors)
+        fig.add_trace(
+            go.Scatter(
+                x=frequency,
+                y=analysis.spectra[selected_position],
+                mode="lines+markers",
+                name=f"C{selected_cylinder:02d}",
+                line=dict(
+                    color=color,
+                    width=3 if selected_cylinder == cylinder else 2,
+                ),
+                marker=dict(size=6 if selected_cylinder == cylinder else 4),
+            )
+        )
+
     top = {
         int(value)
         for value in str(row["top_anomalous_frequencies_khz"]).split("|")
@@ -91,14 +127,22 @@ def cylinder_spectrum(analysis: EngineAnalysis, cylinder: int) -> go.Figure:
         fig.add_vrect(
             x0=value - 0.35,
             x1=value + 0.35,
-            fillcolor=color,
+            fillcolor=primary_color,
             opacity=0.10,
             line_width=0,
         )
-    fig.update_layout(title="Widmo cylindra vs referencja", legend=dict(orientation="h", y=1.14))
+    fig.update_layout(
+        legend=dict(
+            orientation="h",
+            x=0,
+            xanchor="left",
+            y=1.04,
+            yanchor="bottom",
+        )
+    )
     fig.update_xaxes(title="Częstotliwość [kHz]", dtick=1)
     fig.update_yaxes(title="Amplituda [mV]")
-    return _base_layout(fig, height=410)
+    return _base_layout(fig, height=440, margin_top=76, margin_bottom=42)
 
 
 def deviation_chart(analysis: EngineAnalysis, cylinder: int) -> go.Figure:
@@ -116,7 +160,6 @@ def deviation_chart(analysis: EngineAnalysis, cylinder: int) -> go.Figure:
         )
     )
     fig.add_hline(y=0, line_color="#6e8794", line_width=1)
-    fig.update_layout(title="Odchylenie od referencji")
     fig.update_xaxes(title="Częstotliwość [kHz]", dtick=2)
     fig.update_yaxes(title="Różnica [mV]")
-    return _base_layout(fig, height=320)
+    return _base_layout(fig, height=340, margin_top=24, margin_bottom=42)
diff --git a/tests/test_app_smoke.py b/tests/test_app_smoke.py
index d45d526..3b3b452 100644
--- a/tests/test_app_smoke.py
+++ b/tests/test_app_smoke.py
@@ -13,8 +13,12 @@ class StreamlitSmokeTests(unittest.TestCase):
         app = AppTest.from_file(str(ROOT / "app.py"), default_timeout=30).run()
         self.assertEqual(len(app.exception), 0)
         self.assertGreaterEqual(len(app.button), 8)
-        self.assertGreaterEqual(len(app.selectbox), 2)
+        self.assertGreaterEqual(len(app.selectbox), 1)
         self.assertEqual(app.radio[0].value, "Dane demonstracyjne")
+        self.assertEqual(app.segmented_control[0].value, "Przegląd")
+        self.assertFalse(
+            any(selector.label == "Cylinder główny" for selector in app.selectbox)
+        )
 
     def test_upload_mode_has_safe_empty_state(self) -> None:
         app = AppTest.from_file(str(ROOT / "app.py"), default_timeout=30).run()
@@ -26,9 +30,14 @@ class StreamlitSmokeTests(unittest.TestCase):
         app = AppTest.from_file(str(ROOT / "app.py"), default_timeout=30).run()
         target = next(button for button in app.button if "C03" in button.label)
         target.click().run()
+        self.assertEqual(app.segmented_control[0].value, "Szczegóły cylindra")
         detail_selector = next(
-            selector for selector in app.selectbox if selector.label == "Cylinder do analizy"
+            selector for selector in app.selectbox if selector.label == "Cylinder główny"
         )
         self.assertEqual(detail_selector.value, 3)
+        comparison = app.multiselect[0]
+        self.assertEqual(comparison.label, "Porównaj z cylindrami")
+        comparison.set_value([1, 2, 4]).run()
+        self.assertEqual(len(app.exception), 0)
         rendered = "\n".join(markdown.value for markdown in app.markdown)
         self.assertIn("CYLINDER 03", rendered)
diff --git a/tests/test_explainability.py b/tests/test_explainability.py
index 875fa33..40e12b2 100644
--- a/tests/test_explainability.py
+++ b/tests/test_explainability.py
@@ -62,6 +62,11 @@ class ExplainabilityTests(unittest.TestCase):
 
     def test_all_chart_factories_return_populated_figures(self) -> None:
         cylinder = int(self.analysis.measurements["cylinder"].iloc[0])
+        compared = self.analysis.measurements["cylinder"].astype(int).head(4).tolist()
         self.assertEqual(len(engine_heatmap(self.analysis).data), 1)
         self.assertEqual(len(cylinder_spectrum(self.analysis, cylinder).data), 2)
+        self.assertEqual(
+            len(cylinder_spectrum(self.analysis, cylinder, compared).data),
+            5,
+        )
         self.assertEqual(len(deviation_chart(self.analysis, cylinder).data), 1)