diff --git a/plots/campbell-basic/implementations/pygal.py b/plots/campbell-basic/implementations/pygal.py
new file mode 100644
index 0000000000..284790259e
--- /dev/null
+++ b/plots/campbell-basic/implementations/pygal.py
@@ -0,0 +1,156 @@
+""" pyplots.ai
+campbell-basic: Campbell Diagram
+Library: pygal 3.1.0 | Python 3.14.3
+Quality: 92/100 | Created: 2026-02-15
+"""
+
+import numpy as np
+import pygal
+from pygal.style import Style
+
+
+# Data — natural frequencies of a rotor system vs rotational speed
+np.random.seed(42)
+speed_rpm = np.linspace(0, 6000, 80)
+speed_hz = speed_rpm / 60
+
+# Natural frequency modes (Hz) with gyroscopic effects
+mode1 = 25 + 0.003 * speed_rpm + np.random.normal(0, 0.15, len(speed_rpm))
+mode2 = 48 + 0.005 * speed_rpm + np.random.normal(0, 0.15, len(speed_rpm))
+mode3 = 62 - 0.001 * speed_rpm + np.random.normal(0, 0.15, len(speed_rpm))
+mode4 = 78 - 0.002 * speed_rpm + np.random.normal(0, 0.15, len(speed_rpm))
+mode5 = 92 + 0.004 * speed_rpm + np.random.normal(0, 0.15, len(speed_rpm))
+
+orders = [1, 2, 3]
+modes_data = [mode1, mode2, mode3, mode4, mode5]
+mode_names = ["1st Bending", "2nd Bending", "1st Torsional", "Axial", "2nd Torsional"]
+
+# Find critical speed intersections
+critical_speeds = []
+critical_info = []
+for order in orders:
+    eo_freq = order * speed_hz
+    for mi, mode in enumerate(modes_data):
+        diff = eo_freq - mode
+        sign_changes = np.where(np.diff(np.sign(diff)))[0]
+        for idx in sign_changes:
+            frac = abs(diff[idx]) / (abs(diff[idx]) + abs(diff[idx + 1]))
+            rpm_interp = speed_rpm[idx] + frac * (speed_rpm[idx + 1] - speed_rpm[idx])
+            freq_interp = order * rpm_interp / 60
+            if 0 < rpm_interp < 6000:
+                critical_speeds.append((float(rpm_interp), float(freq_interp)))
+                critical_info.append((order, mode_names[mi]))
+
+# Style — stroke_width controls .reactive CSS base width for all line elements
+# Setting it high ensures EO dashed lines are fully visible in CairoSVG PNG rendering
+font = "DejaVu Sans, Helvetica, Arial, sans-serif"
+custom_style = Style(
+    background="white",
+    plot_background="white",
+    foreground="#2a2a2a",
+    foreground_strong="#2a2a2a",
+    foreground_subtle="#d0d0d0",
+    guide_stroke_color="#e4e4e4",
+    guide_stroke_dasharray="4, 6",
+    major_guide_stroke_dasharray="2, 4",
+    colors=(
+        "#306998",  # 1st Bending — Python Blue
+        "#1a9988",  # 2nd Bending — teal
+        "#7b5ea7",  # 1st Torsional — purple
+        "#d4812e",  # Axial — orange
+        "#5a8c3c",  # 2nd Torsional — green
+        "#b71c1c",  # 1x EO — dark red
+        "#0d47a1",  # 2x EO — bold blue
+        "#4a148c",  # 3x EO — bold purple
+        "#d50000",  # Critical Speeds — vivid red
+    ),
+    font_family=font,
+    title_font_family=font,
+    title_font_size=56,
+    label_font_size=42,
+    major_label_font_size=38,
+    legend_font_size=32,
+    legend_font_family=font,
+    value_font_size=28,
+    tooltip_font_size=28,
+    tooltip_font_family=font,
+    opacity=1.0,
+    opacity_hover=1.0,
+    stroke_opacity=1.0,
+    stroke_opacity_hover=1.0,
+    stroke_width=6,
+)
+
+chart = pygal.XY(
+    width=4800,
+    height=2700,
+    style=custom_style,
+    title="campbell-basic · pygal · pyplots.ai",
+    x_title="Rotational Speed (RPM)",
+    y_title="Frequency (Hz)",
+    show_legend=True,
+    legend_at_bottom=True,
+    legend_at_bottom_columns=3,
+    legend_box_size=30,
+    stroke=True,
+    dots_size=0,
+    show_x_guides=True,
+    show_y_guides=True,
+    x_value_formatter=lambda x: f"{x:,.0f}",
+    value_formatter=lambda y: f"{y:.1f}",
+    margin_bottom=80,
+    margin_left=100,
+    margin_right=60,
+    margin_top=50,
+    x_label_rotation=0,
+    truncate_legend=-1,
+    range=(0, 130),
+    xrange=(0, 6000),
+    print_values=False,
+    print_zeroes=False,
+    tooltip_fancy_mode=True,
+    js=[],
+)
+
+# Natural frequency mode curves — solid, thick lines with cubic interpolation
+# Add label point near right end of each curve for direct labeling
+for mode, label in zip(modes_data, mode_names, strict=True):
+    points = []
+    label_idx = int(len(speed_rpm) * 0.82)
+    for j, (r, f) in enumerate(zip(speed_rpm, mode, strict=True)):
+        if j == label_idx:
+            points.append({"value": (float(r), float(f)), "label": label})
+        else:
+            points.append((float(r), float(f)))
+    chart.add(label, points, stroke_style={"width": 10, "linecap": "round"}, show_dots=False, interpolate="cubic")
+
+# Engine order lines — dashed, bold, many sample points for proper rendering
+# Using multiple points along each line ensures CairoSVG renders the full stroke
+eo_labels = ["1× EO", "2× EO", "3× EO"]
+eo_dash_patterns = ["28, 14", "20, 10, 8, 10", "14, 8"]
+for order, eo_label, dash in zip(orders, eo_labels, eo_dash_patterns, strict=True):
+    eo_end_rpm = min(6000.0, 130.0 * 60.0 / order)
+    eo_end_hz = order * eo_end_rpm / 60.0
+    # Generate 40 evenly spaced points so pygal renders a proper visible path
+    eo_rpms = np.linspace(0, eo_end_rpm, 40)
+    eo_freqs = order * eo_rpms / 60.0
+    # Place label near 70% of line length
+    label_idx = int(len(eo_rpms) * 0.70)
+    eo_points = []
+    for j, (r, f) in enumerate(zip(eo_rpms, eo_freqs, strict=True)):
+        if j == label_idx:
+            eo_points.append({"value": (float(r), float(f)), "label": eo_label})
+        else:
+            eo_points.append((float(r), float(f)))
+    chart.add(eo_label, eo_points, stroke_style={"width": 8, "dasharray": dash, "linecap": "round"}, show_dots=False)
+
+# Critical speed markers — vivid red with tooltip showing intersection details
+critical_points = []
+for pt, info in zip(critical_speeds, critical_info, strict=True):
+    order, mname = info
+    critical_points.append({"value": pt, "label": f"{mname} × {order}× EO\n{pt[0]:.0f} RPM / {pt[1]:.1f} Hz"})
+chart.add("Critical Speeds", critical_points, stroke=False, dots_size=22)
+
+# Render both SVG/HTML (leveraging pygal's native SVG interactivity) and PNG
+chart.render_to_file("plot.html")
+chart.render_to_png("plot.png")
diff --git a/plots/campbell-basic/metadata/pygal.yaml b/plots/campbell-basic/metadata/pygal.yaml
new file mode 100644
index 0000000000..4fde78663b
--- /dev/null
+++ b/plots/campbell-basic/metadata/pygal.yaml
@@ -0,0 +1,238 @@
+library: pygal
+specification_id: campbell-basic
+created: '2026-02-15T21:09:18Z'
+updated: '2026-02-15T21:36:47Z'
+generated_by: claude-opus-4-5-20251101
+workflow_run: 22043026953
+issue: 4241
+python_version: 3.14.3
+library_version: 3.1.0
+preview_url: https://storage.googleapis.com/pyplots-images/plots/campbell-basic/pygal/plot.png
+preview_thumb: https://storage.googleapis.com/pyplots-images/plots/campbell-basic/pygal/plot_thumb.png
+preview_html: https://storage.googleapis.com/pyplots-images/plots/campbell-basic/pygal/plot.html
+quality_score: 92
+review:
+  strengths:
+  - 'Comprehensive Campbell Diagram with all required elements: 5 mode curves, 3 engine
+    order lines, and critical speed markers with detailed intersection info'
+  - Excellent font sizing and styling explicitly configured for 4800x2700 resolution
+    - all text is clearly legible
+  - 'Effective visual hierarchy: thick solid lines for modes, dashed lines for engine
+    orders, large red dots for critical speeds - viewer immediately understands the
+    diagram'
+  - Strong use of pygal-specific features including per-point label dicts, dual output
+    (SVG+PNG), and cubic interpolation for smooth curves
+  - Realistic engineering data with proper mode naming conventions and physically
+    plausible frequency-speed relationships
+  weaknesses:
+  - The 2x EO dark blue dashed line (#0d47a1) is somewhat similar to the 1st Bending
+    solid blue (#306998) - using a more contrasting color for EO lines would improve
+    differentiation
+  - Engine order lines could benefit from slightly thicker strokes or more prominent
+    dash patterns to stand out more distinctly from the mode curves in the PNG rendering
+  image_description: 'The plot displays a Campbell Diagram with the title "campbell-basic
+    · pygal · pyplots.ai" at the top. The X-axis shows "Rotational Speed (RPM)" ranging
+    from 0 to 6,000, and the Y-axis shows "Frequency (Hz)" from 0.0 to 130.0. Five
+    natural frequency mode curves are rendered as thick solid lines: 1st Bending (blue,
+    rising gently from ~25 Hz), 2nd Bending (teal, rising from ~49 Hz), 1st Torsional
+    (purple, declining slightly from ~62 Hz), Axial (orange, declining from ~78 Hz),
+    and 2nd Torsional (green, rising from ~92 Hz). Three engine order excitation lines
+    are drawn as dashed diagonals from the origin: 1x EO (red dashed), 2x EO (dark
+    blue dashed), and 3x EO (purple dashed). Large vivid red dots mark Critical Speed
+    intersections where engine order lines cross natural frequency curves. A legend
+    at the bottom in three columns identifies all nine series. The background is white
+    with subtle gray grid lines. The overall layout is clean and well-proportioned.'
+  criteria_checklist:
+    visual_quality:
+      score: 29
+      max: 30
+      items:
+      - id: VQ-01
+        name: Text Legibility
+        score: 8
+        max: 8
+        passed: true
+        comment: All font sizes explicitly set (title=56, label=42, major_label=38,
+          legend=32). All text clearly readable.
+      - id: VQ-02
+        name: No Overlap
+        score: 6
+        max: 6
+        passed: true
+        comment: No overlapping text elements. Legend at bottom well-organized in
+          3 columns.
+      - id: VQ-03
+        name: Element Visibility
+        score: 6
+        max: 6
+        passed: true
+        comment: Mode curves stroke width 10, EO lines width 8, critical dots size
+          22. All well-visible.
+      - id: VQ-04
+        name: Color Accessibility
+        score: 3
+        max: 4
+        passed: true
+        comment: Colors generally distinguishable but 2x EO dark blue somewhat close
+          to 1st Bending blue. Mitigated by different line styles.
+      - id: VQ-05
+        name: Layout Balance
+        score: 4
+        max: 4
+        passed: true
+        comment: Plot fills canvas well with balanced margins. Good utilization of
+          4800x2700 canvas.
+      - id: VQ-06
+        name: Axis Labels & Title
+        score: 2
+        max: 2
+        passed: true
+        comment: 'Both axes have descriptive labels with units: Rotational Speed (RPM)
+          and Frequency (Hz).'
+    design_excellence:
+      score: 14
+      max: 20
+      items:
+      - id: DE-01
+        name: Aesthetic Sophistication
+        score: 6
+        max: 8
+        passed: true
+        comment: Custom color palette with intentional hierarchy, explicit font family,
+          subtle grid styling. Strong design above defaults.
+      - id: DE-02
+        name: Visual Refinement
+        score: 4
+        max: 6
+        passed: true
+        comment: Custom grid dash patterns, subtle guide colors, generous margins,
+          clean white background.
+      - id: DE-03
+        name: Data Storytelling
+        score: 4
+        max: 6
+        passed: true
+        comment: 'Visual hierarchy guides the reader: thick solid for modes, dashed
+          for EO, large red dots for critical speeds.'
+    spec_compliance:
+      score: 15
+      max: 15
+      items:
+      - id: SC-01
+        name: Plot Type
+        score: 5
+        max: 5
+        passed: true
+        comment: Correct Campbell Diagram with natural frequency curves, engine order
+          lines, and critical speed markers.
+      - id: SC-02
+        name: Required Features
+        score: 4
+        max: 4
+        passed: true
+        comment: 'All spec features present: 5 modes, 3 EO lines, critical speed markers
+          with labels.'
+      - id: SC-03
+        name: Data Mapping
+        score: 3
+        max: 3
+        passed: true
+        comment: X=RPM, Y=Frequency(Hz). Correct assignment with proper range.
+      - id: SC-04
+        name: Title & Legend
+        score: 3
+        max: 3
+        passed: true
+        comment: Title matches required format. Legend labels correctly identify all
+          data series.
+    data_quality:
+      score: 15
+      max: 15
+      items:
+      - id: DQ-01
+        name: Feature Coverage
+        score: 6
+        max: 6
+        passed: true
+        comment: Shows 5 modes with increasing and decreasing frequency trends, 3
+          engine orders, multiple critical speed intersections.
+      - id: DQ-02
+        name: Realistic Context
+        score: 5
+        max: 5
+        passed: true
+        comment: Rotordynamic analysis with proper engineering mode names. Authentic
+          domain vocabulary.
+      - id: DQ-03
+        name: Appropriate Scale
+        score: 4
+        max: 4
+        passed: true
+        comment: 0-6000 RPM range, 25-92 Hz base frequencies. Realistic for rotating
+          machinery.
+    code_quality:
+      score: 10
+      max: 10
+      items:
+      - id: CQ-01
+        name: KISS Structure
+        score: 3
+        max: 3
+        passed: true
+        comment: 'Clean flow: Imports, Seed, Data, Style, Chart, Series, Render. No
+          functions or classes.'
+      - id: CQ-02
+        name: Reproducibility
+        score: 2
+        max: 2
+        passed: true
+        comment: np.random.seed(42) set at the start.
+      - id: CQ-03
+        name: Clean Imports
+        score: 2
+        max: 2
+        passed: true
+        comment: Only numpy, pygal, and Style imported - all used.
+      - id: CQ-04
+        name: Code Elegance
+        score: 2
+        max: 2
+        passed: true
+        comment: Clean, Pythonic code with appropriately complex intersection-finding
+          logic.
+      - id: CQ-05
+        name: Output & API
+        score: 1
+        max: 1
+        passed: true
+        comment: Saves as plot.png and plot.html. No deprecated API usage.
+    library_mastery:
+      score: 9
+      max: 10
+      items:
+      - id: LM-01
+        name: Idiomatic Usage
+        score: 5
+        max: 5
+        passed: true
+        comment: Expert use of pygal.XY with Style, per-series stroke_style, value
+          formatters, legend config, cubic interpolation.
+      - id: LM-02
+        name: Distinctive Features
+        score: 4
+        max: 5
+        passed: true
+        comment: Uses pygal-specific per-point label dicts, native SVG interactivity,
+          cubic interpolation, stroke_style dasharray.
+  verdict: APPROVED
+impl_tags:
+  dependencies: []
+  techniques:
+  - html-export
+  patterns:
+  - data-generation
+  - iteration-over-groups
+  dataprep:
+  - interpolation
+  styling:
+  - grid-styling