From 9c10deb6628a0aeb9a5e09c6a236dd075ca7ea6d Mon Sep 17 00:00:00 2001
From: "github-actions[bot]" <github-actions[bot]@users.noreply.github.com>
Date: Fri, 26 Dec 2025 19:35:34 +0000
Subject: [PATCH 1/9] feat(pygal): implement residual-plot
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

🤖 Generated with [Claude Code](https://claude.ai/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
---
 plots/residual-plot/implementations/pygal.py | 87 ++++++++++++++++++++
 1 file changed, 87 insertions(+)
 create mode 100644 plots/residual-plot/implementations/pygal.py

diff --git a/plots/residual-plot/implementations/pygal.py b/plots/residual-plot/implementations/pygal.py
new file mode 100644
index 0000000000..d388a79d81
--- /dev/null
+++ b/plots/residual-plot/implementations/pygal.py
@@ -0,0 +1,87 @@
+"""pyplots.ai
+residual-plot: Residual Plot
+Library: pygal | Python 3.13
+Quality: pending | Created: 2025-12-26
+"""
+
+import numpy as np
+import pygal
+from pygal.style import Style
+
+
+# Data - Linear regression example with some non-linearity
+np.random.seed(42)
+n_points = 100
+
+# Generate fitted values (x-axis)
+fitted_values = np.linspace(10, 100, n_points)
+
+# Generate residuals with slight heteroscedasticity and a few outliers
+base_residuals = np.random.normal(0, 5, n_points)
+# Add slight heteroscedasticity (variance increases with fitted values)
+heteroscedasticity = (fitted_values / 100) * np.random.normal(0, 3, n_points)
+residuals = base_residuals + heteroscedasticity
+
+# Add a few outliers
+outlier_indices = [15, 45, 78]
+residuals[outlier_indices] = [25, -22, 28]
+
+# Calculate standard deviation for reference bands
+std_residuals = np.std(residuals)
+
+# Identify outliers (beyond 2 standard deviations)
+outlier_mask = np.abs(residuals) > 2 * std_residuals
+
+# Custom style for 4800x2700 canvas
+custom_style = Style(
+    background="white",
+    plot_background="white",
+    foreground="#333333",
+    foreground_strong="#333333",
+    foreground_subtle="#666666",
+    colors=("#306998", "#E74C3C", "#888888"),  # Python Blue, red for outliers, gray for zero line
+    title_font_size=60,
+    label_font_size=44,
+    major_label_font_size=40,
+    legend_font_size=40,
+    value_font_size=32,
+    tooltip_font_size=32,
+    stroke_width=3,
+)
+
+# Create XY scatter chart for residual plot
+chart = pygal.XY(
+    width=4800,
+    height=2700,
+    style=custom_style,
+    title="residual-plot · pygal · pyplots.ai",
+    x_title="Fitted Values",
+    y_title="Residuals",
+    show_legend=True,
+    legend_at_bottom=True,
+    legend_at_bottom_columns=3,
+    show_x_guides=True,
+    show_y_guides=True,
+    stroke=False,
+    dots_size=18,
+    truncate_legend=-1,
+    x_label_rotation=0,
+)
+
+# Prepare data points - separate normal and outlier points
+normal_points = [(float(fitted_values[i]), float(residuals[i])) for i in range(n_points) if not outlier_mask[i]]
+outlier_points = [(float(fitted_values[i]), float(residuals[i])) for i in range(n_points) if outlier_mask[i]]
+
+# Add data series
+chart.add("Residuals", normal_points)
+chart.add("Outliers (>2σ)", outlier_points)
+
+# Add zero reference line (using Line chart overlay via XY with same points)
+zero_line_points = [(float(fitted_values[0]), 0), (float(fitted_values[-1]), 0)]
+chart.add(
+    "Zero Reference", zero_line_points, stroke=True, show_dots=False, stroke_style={"width": 4, "dasharray": "15, 10"}
+)
+
+# Save as PNG and HTML
+chart.render_to_png("plot.png")
+chart.render_to_file("plot.html")

From 11eb295b1d0b5bfe867bc2e2160b335ea59858d4 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]" <github-actions[bot]@users.noreply.github.com>
Date: Fri, 26 Dec 2025 19:35:50 +0000
Subject: [PATCH 2/9] chore(pygal): add metadata for residual-plot

---
 plots/residual-plot/metadata/pygal.yaml | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)
 create mode 100644 plots/residual-plot/metadata/pygal.yaml

diff --git a/plots/residual-plot/metadata/pygal.yaml b/plots/residual-plot/metadata/pygal.yaml
new file mode 100644
index 0000000000..0a18582d7f
--- /dev/null
+++ b/plots/residual-plot/metadata/pygal.yaml
@@ -0,0 +1,19 @@
+# Per-library metadata for pygal implementation of residual-plot
+# Auto-generated by impl-generate.yml
+
+library: pygal
+specification_id: residual-plot
+created: '2025-12-26T19:35:50Z'
+updated: '2025-12-26T19:35:50Z'
+generated_by: claude-opus-4-5-20251101
+workflow_run: 20528206404
+issue: 0
+python_version: 3.13.11
+library_version: 3.1.0
+preview_url: https://storage.googleapis.com/pyplots-images/plots/residual-plot/pygal/plot.png
+preview_thumb: https://storage.googleapis.com/pyplots-images/plots/residual-plot/pygal/plot_thumb.png
+preview_html: https://storage.googleapis.com/pyplots-images/plots/residual-plot/pygal/plot.html
+quality_score: null
+review:
+  strengths: []
+  weaknesses: []

From 1ab7a2ec4752913118b56a8a30c729c0c4717f0f Mon Sep 17 00:00:00 2001
From: "github-actions[bot]" <github-actions[bot]@users.noreply.github.com>
Date: Fri, 26 Dec 2025 19:40:27 +0000
Subject: [PATCH 3/9] chore(pygal): update quality score 88 and review feedback
 for residual-plot

---
 plots/residual-plot/implementations/pygal.py |  6 +++---
 plots/residual-plot/metadata/pygal.yaml      | 22 +++++++++++++-------
 2 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/plots/residual-plot/implementations/pygal.py b/plots/residual-plot/implementations/pygal.py
index d388a79d81..1d33d8570e 100644
--- a/plots/residual-plot/implementations/pygal.py
+++ b/plots/residual-plot/implementations/pygal.py
@@ -1,7 +1,7 @@
-"""pyplots.ai
+""" pyplots.ai
 residual-plot: Residual Plot
-Library: pygal | Python 3.13
-Quality: pending | Created: 2025-12-26
+Library: pygal 3.1.0 | Python 3.13.11
+Quality: 88/100 | Created: 2025-12-26
 """
 
 import numpy as np
diff --git a/plots/residual-plot/metadata/pygal.yaml b/plots/residual-plot/metadata/pygal.yaml
index 0a18582d7f..54db535293 100644
--- a/plots/residual-plot/metadata/pygal.yaml
+++ b/plots/residual-plot/metadata/pygal.yaml
@@ -1,10 +1,7 @@
-# Per-library metadata for pygal implementation of residual-plot
-# Auto-generated by impl-generate.yml
-
 library: pygal
 specification_id: residual-plot
 created: '2025-12-26T19:35:50Z'
-updated: '2025-12-26T19:35:50Z'
+updated: '2025-12-26T19:40:27Z'
 generated_by: claude-opus-4-5-20251101
 workflow_run: 20528206404
 issue: 0
@@ -13,7 +10,18 @@ library_version: 3.1.0
 preview_url: https://storage.googleapis.com/pyplots-images/plots/residual-plot/pygal/plot.png
 preview_thumb: https://storage.googleapis.com/pyplots-images/plots/residual-plot/pygal/plot_thumb.png
 preview_html: https://storage.googleapis.com/pyplots-images/plots/residual-plot/pygal/plot.html
-quality_score: null
+quality_score: 88
 review:
-  strengths: []
-  weaknesses: []
+  strengths:
+  - Excellent implementation of outlier detection and visualization with distinct
+    coloring
+  - Clean separation of normal residuals vs outliers using mask
+  - Zero reference line implemented with dashed stroke style
+  - Demonstrates heteroscedasticity pattern effectively
+  - Font sizes appropriately scaled for 4800x2700 canvas
+  - Proper use of pygal XY chart for scatter data
+  weaknesses:
+  - Missing ±2σ horizontal bands which would enhance diagnostic value
+  - Axis labels lack units (generic Fitted Values and Residuals)
+  - Legend entry for Zero Reference shows colored square instead of line representation
+  - Font sizes in Style deviate from library guide recommendations

From d09288b46007ecf72759dcecda8fd6c1b0b4d097 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]" <github-actions[bot]@users.noreply.github.com>
Date: Fri, 26 Dec 2025 19:44:00 +0000
Subject: [PATCH 4/9] fix(pygal): address review feedback for residual-plot
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

- Add ±2σ horizontal threshold bands for improved diagnostic value
- Add descriptive axis labels with units (house price context in $1000s)
- Improve legend labels for reference lines (y=0, +2σ, −2σ)
- Adjust font sizes to match library guide recommendations

Attempt 1/3 - fixes based on AI review

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
---
 plots/residual-plot/implementations/pygal.py | 61 +++++++++++++-------
 1 file changed, 40 insertions(+), 21 deletions(-)

diff --git a/plots/residual-plot/implementations/pygal.py b/plots/residual-plot/implementations/pygal.py
index 1d33d8570e..3eebc31995 100644
--- a/plots/residual-plot/implementations/pygal.py
+++ b/plots/residual-plot/implementations/pygal.py
@@ -1,4 +1,4 @@
-""" pyplots.ai
+"""pyplots.ai
 residual-plot: Residual Plot
 Library: pygal 3.1.0 | Python 3.13.11
 Quality: 88/100 | Created: 2025-12-26
@@ -13,39 +13,41 @@
 np.random.seed(42)
 n_points = 100
 
-# Generate fitted values (x-axis)
-fitted_values = np.linspace(10, 100, n_points)
+# Generate fitted values (x-axis) - house price predictions in $1000s
+fitted_values = np.linspace(150, 500, n_points)
 
 # Generate residuals with slight heteroscedasticity and a few outliers
-base_residuals = np.random.normal(0, 5, n_points)
+base_residuals = np.random.normal(0, 20, n_points)
 # Add slight heteroscedasticity (variance increases with fitted values)
-heteroscedasticity = (fitted_values / 100) * np.random.normal(0, 3, n_points)
+heteroscedasticity = (fitted_values / 500) * np.random.normal(0, 15, n_points)
 residuals = base_residuals + heteroscedasticity
 
 # Add a few outliers
 outlier_indices = [15, 45, 78]
-residuals[outlier_indices] = [25, -22, 28]
+residuals[outlier_indices] = [85, -75, 90]
 
 # Calculate standard deviation for reference bands
 std_residuals = np.std(residuals)
+upper_band = 2 * std_residuals
+lower_band = -2 * std_residuals
 
 # Identify outliers (beyond 2 standard deviations)
 outlier_mask = np.abs(residuals) > 2 * std_residuals
 
-# Custom style for 4800x2700 canvas
+# Custom style for 4800x2700 canvas following library guide recommendations
 custom_style = Style(
     background="white",
     plot_background="white",
     foreground="#333333",
     foreground_strong="#333333",
     foreground_subtle="#666666",
-    colors=("#306998", "#E74C3C", "#888888"),  # Python Blue, red for outliers, gray for zero line
-    title_font_size=60,
-    label_font_size=44,
-    major_label_font_size=40,
-    legend_font_size=40,
-    value_font_size=32,
-    tooltip_font_size=32,
+    colors=("#306998", "#E74C3C", "#666666", "#95a5a6", "#95a5a6"),
+    title_font_size=28,
+    label_font_size=18,
+    major_label_font_size=16,
+    legend_font_size=16,
+    value_font_size=14,
+    tooltip_font_size=14,
     stroke_width=3,
 )
 
@@ -55,15 +57,15 @@
     height=2700,
     style=custom_style,
     title="residual-plot · pygal · pyplots.ai",
-    x_title="Fitted Values",
-    y_title="Residuals",
+    x_title="Fitted Values (Predicted Price in $1000s)",
+    y_title="Residuals (Actual - Predicted in $1000s)",
     show_legend=True,
     legend_at_bottom=True,
-    legend_at_bottom_columns=3,
+    legend_at_bottom_columns=5,
     show_x_guides=True,
     show_y_guides=True,
     stroke=False,
-    dots_size=18,
+    dots_size=12,
     truncate_legend=-1,
     x_label_rotation=0,
 )
@@ -76,10 +78,27 @@
 chart.add("Residuals", normal_points)
 chart.add("Outliers (>2σ)", outlier_points)
 
-# Add zero reference line (using Line chart overlay via XY with same points)
-zero_line_points = [(float(fitted_values[0]), 0), (float(fitted_values[-1]), 0)]
+# Add zero reference line (dashed)
+x_min, x_max = float(fitted_values[0]), float(fitted_values[-1])
+zero_line_points = [(x_min, 0), (x_max, 0)]
 chart.add(
-    "Zero Reference", zero_line_points, stroke=True, show_dots=False, stroke_style={"width": 4, "dasharray": "15, 10"}
+    "y = 0 (Perfect Fit)",
+    zero_line_points,
+    stroke=True,
+    show_dots=False,
+    stroke_style={"width": 4, "dasharray": "15, 10"},
+)
+
+# Add +2σ reference band line
+upper_band_points = [(x_min, float(upper_band)), (x_max, float(upper_band))]
+chart.add(
+    "+2σ Threshold", upper_band_points, stroke=True, show_dots=False, stroke_style={"width": 2, "dasharray": "8, 6"}
+)
+
+# Add -2σ reference band line
+lower_band_points = [(x_min, float(lower_band)), (x_max, float(lower_band))]
+chart.add(
+    "−2σ Threshold", lower_band_points, stroke=True, show_dots=False, stroke_style={"width": 2, "dasharray": "8, 6"}
 )
 
 # Save as PNG and HTML

From b7a43332091e9a9634368ed7f0936a89671b350a Mon Sep 17 00:00:00 2001
From: "github-actions[bot]" <github-actions[bot]@users.noreply.github.com>
Date: Fri, 26 Dec 2025 19:46:28 +0000
Subject: [PATCH 5/9] chore(pygal): update quality score 78 and review feedback
 for residual-plot

---
 plots/residual-plot/implementations/pygal.py |  4 +--
 plots/residual-plot/metadata/pygal.yaml      | 27 ++++++++++----------
 2 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/plots/residual-plot/implementations/pygal.py b/plots/residual-plot/implementations/pygal.py
index 3eebc31995..08cdc1407e 100644
--- a/plots/residual-plot/implementations/pygal.py
+++ b/plots/residual-plot/implementations/pygal.py
@@ -1,7 +1,7 @@
-"""pyplots.ai
+""" pyplots.ai
 residual-plot: Residual Plot
 Library: pygal 3.1.0 | Python 3.13.11
-Quality: 88/100 | Created: 2025-12-26
+Quality: 78/100 | Created: 2025-12-26
 """
 
 import numpy as np
diff --git a/plots/residual-plot/metadata/pygal.yaml b/plots/residual-plot/metadata/pygal.yaml
index 54db535293..b701975b50 100644
--- a/plots/residual-plot/metadata/pygal.yaml
+++ b/plots/residual-plot/metadata/pygal.yaml
@@ -1,7 +1,7 @@
 library: pygal
 specification_id: residual-plot
 created: '2025-12-26T19:35:50Z'
-updated: '2025-12-26T19:40:27Z'
+updated: '2025-12-26T19:46:28Z'
 generated_by: claude-opus-4-5-20251101
 workflow_run: 20528206404
 issue: 0
@@ -10,18 +10,19 @@ library_version: 3.1.0
 preview_url: https://storage.googleapis.com/pyplots-images/plots/residual-plot/pygal/plot.png
 preview_thumb: https://storage.googleapis.com/pyplots-images/plots/residual-plot/pygal/plot_thumb.png
 preview_html: https://storage.googleapis.com/pyplots-images/plots/residual-plot/pygal/plot.html
-quality_score: 88
+quality_score: 78
 review:
   strengths:
-  - Excellent implementation of outlier detection and visualization with distinct
-    coloring
-  - Clean separation of normal residuals vs outliers using mask
-  - Zero reference line implemented with dashed stroke style
-  - Demonstrates heteroscedasticity pattern effectively
-  - Font sizes appropriately scaled for 4800x2700 canvas
-  - Proper use of pygal XY chart for scatter data
+  - Proper separation of normal residuals and outliers with distinct colors
+  - Correct title format following pyplots.ai conventions
+  - Good use of custom Style for canvas sizing and fonts
+  - Realistic house price prediction scenario with heteroscedasticity
+  - Clean KISS code structure with proper reproducibility (seed=42)
+  - Good dot sizing for the data density (100 points)
   weaknesses:
-  - Missing ±2σ horizontal bands which would enhance diagnostic value
-  - Axis labels lack units (generic Fitted Values and Residuals)
-  - Legend entry for Zero Reference shows colored square instead of line representation
-  - Font sizes in Style deviate from library guide recommendations
+  - 'X-axis values render incorrectly: code specifies fitted values 150-500 but plot
+    shows 10-100 (pygal may be using index positions)'
+  - Axis labels lose their units in rendering (should show $1000s suffix)
+  - The ±2σ threshold dashed lines are not visible in the rendered output despite
+    being added to the chart
+  - 'Legend label mismatch: Zero Reference rendered vs y = 0 (Perfect Fit) in code'

From 8802433237effa2812ffd5ad5aa30685230a8289 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]" <github-actions[bot]@users.noreply.github.com>
Date: Fri, 26 Dec 2025 19:51:12 +0000
Subject: [PATCH 6/9] fix(pygal): address review feedback for residual-plot
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Attempt 2/3 - fixes based on AI review:
- Fix X-axis values to show actual fitted values (150-500) using explicit x_labels and xrange
- Add units to axis labels (000s suffix)
- Make ±2σ threshold dashed lines visible with more points and proper stroke style
- Fix legend labels for consistency (Zero Reference instead of y=0)
- Set explicit y-axis range to accommodate outliers
---
 plots/residual-plot/implementations/pygal.py | 39 ++++++++++----------
 1 file changed, 19 insertions(+), 20 deletions(-)

diff --git a/plots/residual-plot/implementations/pygal.py b/plots/residual-plot/implementations/pygal.py
index 08cdc1407e..c4116874db 100644
--- a/plots/residual-plot/implementations/pygal.py
+++ b/plots/residual-plot/implementations/pygal.py
@@ -1,4 +1,4 @@
-""" pyplots.ai
+"""pyplots.ai
 residual-plot: Residual Plot
 Library: pygal 3.1.0 | Python 3.13.11
 Quality: 78/100 | Created: 2025-12-26
@@ -41,7 +41,7 @@
     foreground="#333333",
     foreground_strong="#333333",
     foreground_subtle="#666666",
-    colors=("#306998", "#E74C3C", "#666666", "#95a5a6", "#95a5a6"),
+    colors=("#306998", "#E74C3C", "#2C3E50", "#7F8C8D", "#7F8C8D"),
     title_font_size=28,
     label_font_size=18,
     major_label_font_size=16,
@@ -52,13 +52,14 @@
 )
 
 # Create XY scatter chart for residual plot
+# Use explicit x_labels to control axis display and range settings
 chart = pygal.XY(
     width=4800,
     height=2700,
     style=custom_style,
     title="residual-plot · pygal · pyplots.ai",
-    x_title="Fitted Values (Predicted Price in $1000s)",
-    y_title="Residuals (Actual - Predicted in $1000s)",
+    x_title="Fitted Values - Predicted Price ($1000s)",
+    y_title="Residuals - Actual minus Predicted ($1000s)",
     show_legend=True,
     legend_at_bottom=True,
     legend_at_bottom_columns=5,
@@ -68,8 +69,13 @@
     dots_size=12,
     truncate_legend=-1,
     x_label_rotation=0,
+    xrange=(140, 510),
+    range=(-100, 110),
 )
 
+# Set explicit x-axis labels to display actual fitted values (not indices)
+chart.x_labels = [150, 200, 250, 300, 350, 400, 450, 500]
+
 # Prepare data points - separate normal and outlier points
 normal_points = [(float(fitted_values[i]), float(residuals[i])) for i in range(n_points) if not outlier_mask[i]]
 outlier_points = [(float(fitted_values[i]), float(residuals[i])) for i in range(n_points) if outlier_mask[i]]
@@ -78,27 +84,20 @@
 chart.add("Residuals", normal_points)
 chart.add("Outliers (>2σ)", outlier_points)
 
-# Add zero reference line (dashed)
-x_min, x_max = float(fitted_values[0]), float(fitted_values[-1])
-zero_line_points = [(x_min, 0), (x_max, 0)]
-chart.add(
-    "y = 0 (Perfect Fit)",
-    zero_line_points,
-    stroke=True,
-    show_dots=False,
-    stroke_style={"width": 4, "dasharray": "15, 10"},
-)
+# Add zero reference line - create more points for solid appearance
+zero_line_points = [(float(x), 0.0) for x in np.linspace(150, 500, 50)]
+chart.add("Zero Reference (Perfect Fit)", zero_line_points, stroke=True, show_dots=False, stroke_style={"width": 5})
 
-# Add +2σ reference band line
-upper_band_points = [(x_min, float(upper_band)), (x_max, float(upper_band))]
+# Add +2σ reference band line with multiple points for visibility
+upper_band_points = [(float(x), float(upper_band)) for x in np.linspace(150, 500, 50)]
 chart.add(
-    "+2σ Threshold", upper_band_points, stroke=True, show_dots=False, stroke_style={"width": 2, "dasharray": "8, 6"}
+    "+2σ Threshold", upper_band_points, stroke=True, show_dots=False, stroke_style={"width": 3, "dasharray": "10, 8"}
 )
 
-# Add -2σ reference band line
-lower_band_points = [(x_min, float(lower_band)), (x_max, float(lower_band))]
+# Add -2σ reference band line with multiple points for visibility
+lower_band_points = [(float(x), float(lower_band)) for x in np.linspace(150, 500, 50)]
 chart.add(
-    "−2σ Threshold", lower_band_points, stroke=True, show_dots=False, stroke_style={"width": 2, "dasharray": "8, 6"}
+    "-2σ Threshold", lower_band_points, stroke=True, show_dots=False, stroke_style={"width": 3, "dasharray": "10, 8"}
 )
 
 # Save as PNG and HTML

From 6724501e15083f8b0fa6b3543d10079dce5ae211 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]" <github-actions[bot]@users.noreply.github.com>
Date: Fri, 26 Dec 2025 19:53:59 +0000
Subject: [PATCH 7/9] chore(pygal): update quality score 85 and review feedback
 for residual-plot

---
 plots/residual-plot/implementations/pygal.py |  4 ++--
 plots/residual-plot/metadata/pygal.yaml      | 24 ++++++++------------
 2 files changed, 12 insertions(+), 16 deletions(-)

diff --git a/plots/residual-plot/implementations/pygal.py b/plots/residual-plot/implementations/pygal.py
index c4116874db..965d6bdc89 100644
--- a/plots/residual-plot/implementations/pygal.py
+++ b/plots/residual-plot/implementations/pygal.py
@@ -1,7 +1,7 @@
-"""pyplots.ai
+""" pyplots.ai
 residual-plot: Residual Plot
 Library: pygal 3.1.0 | Python 3.13.11
-Quality: 78/100 | Created: 2025-12-26
+Quality: 85/100 | Created: 2025-12-26
 """
 
 import numpy as np
diff --git a/plots/residual-plot/metadata/pygal.yaml b/plots/residual-plot/metadata/pygal.yaml
index b701975b50..db4bdc7301 100644
--- a/plots/residual-plot/metadata/pygal.yaml
+++ b/plots/residual-plot/metadata/pygal.yaml
@@ -1,7 +1,7 @@
 library: pygal
 specification_id: residual-plot
 created: '2025-12-26T19:35:50Z'
-updated: '2025-12-26T19:46:28Z'
+updated: '2025-12-26T19:53:58Z'
 generated_by: claude-opus-4-5-20251101
 workflow_run: 20528206404
 issue: 0
@@ -10,19 +10,15 @@ library_version: 3.1.0
 preview_url: https://storage.googleapis.com/pyplots-images/plots/residual-plot/pygal/plot.png
 preview_thumb: https://storage.googleapis.com/pyplots-images/plots/residual-plot/pygal/plot_thumb.png
 preview_html: https://storage.googleapis.com/pyplots-images/plots/residual-plot/pygal/plot.html
-quality_score: 78
+quality_score: 85
 review:
   strengths:
-  - Proper separation of normal residuals and outliers with distinct colors
-  - Correct title format following pyplots.ai conventions
-  - Good use of custom Style for canvas sizing and fonts
-  - Realistic house price prediction scenario with heteroscedasticity
-  - Clean KISS code structure with proper reproducibility (seed=42)
-  - Good dot sizing for the data density (100 points)
+  - 'Excellent implementation of all spec requirements: zero reference line, ±2σ threshold
+    bands, and outlier highlighting in different color'
+  - Realistic house price prediction context with appropriate heteroscedasticity pattern
+  - Clean code structure following KISS principles with proper random seed
+  - Good use of pygal XY chart with custom styling for high-resolution output
+  - Proper axis labels with units and correct title format
   weaknesses:
-  - 'X-axis values render incorrectly: code specifies fitted values 150-500 but plot
-    shows 10-100 (pygal may be using index positions)'
-  - Axis labels lose their units in rendering (should show $1000s suffix)
-  - The ±2σ threshold dashed lines are not visible in the rendered output despite
-    being added to the chart
-  - 'Legend label mismatch: Zero Reference rendered vs y = 0 (Perfect Fit) in code'
+  - Legend text at bottom is too small to read clearly at the rendered scale
+  - Grid guides could be more subtle (lower alpha) for better visual balance

From 749008271490bb4556cd3296a2ab945895335a85 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]" <github-actions[bot]@users.noreply.github.com>
Date: Fri, 26 Dec 2025 19:56:59 +0000
Subject: [PATCH 8/9] fix(pygal): address review feedback for residual-plot

Attempt 3/3 - fixes based on AI review:
- Increased legend_font_size from 16 to 24 for better readability
- Increased all font sizes for improved text legibility
- Added subtle grid styling with lighter color (#DDDDDD) and dashed lines
- Lightened threshold band colors for better visual balance
---
 plots/residual-plot/implementations/pygal.py | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/plots/residual-plot/implementations/pygal.py b/plots/residual-plot/implementations/pygal.py
index 965d6bdc89..a9a5d457f5 100644
--- a/plots/residual-plot/implementations/pygal.py
+++ b/plots/residual-plot/implementations/pygal.py
@@ -1,4 +1,4 @@
-""" pyplots.ai
+"""pyplots.ai
 residual-plot: Residual Plot
 Library: pygal 3.1.0 | Python 3.13.11
 Quality: 85/100 | Created: 2025-12-26
@@ -40,15 +40,17 @@
     plot_background="white",
     foreground="#333333",
     foreground_strong="#333333",
-    foreground_subtle="#666666",
-    colors=("#306998", "#E74C3C", "#2C3E50", "#7F8C8D", "#7F8C8D"),
-    title_font_size=28,
-    label_font_size=18,
-    major_label_font_size=16,
-    legend_font_size=16,
-    value_font_size=14,
-    tooltip_font_size=14,
+    foreground_subtle="#999999",
+    colors=("#306998", "#E74C3C", "#2C3E50", "#AAAAAA", "#AAAAAA"),
+    title_font_size=32,
+    label_font_size=22,
+    major_label_font_size=20,
+    legend_font_size=24,
+    value_font_size=16,
+    tooltip_font_size=16,
     stroke_width=3,
+    guide_stroke_color="#DDDDDD",
+    guide_stroke_dasharray="3, 3",
 )
 
 # Create XY scatter chart for residual plot

From a6c501015c47a3e1c0a32c97623a40576c56d78e Mon Sep 17 00:00:00 2001
From: "github-actions[bot]" <github-actions[bot]@users.noreply.github.com>
Date: Fri, 26 Dec 2025 19:59:17 +0000
Subject: [PATCH 9/9] chore(pygal): update quality score 88 and review feedback
 for residual-plot

---
 plots/residual-plot/implementations/pygal.py |  4 ++--
 plots/residual-plot/metadata/pygal.yaml      | 23 +++++++++++---------
 2 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/plots/residual-plot/implementations/pygal.py b/plots/residual-plot/implementations/pygal.py
index a9a5d457f5..45b43215c9 100644
--- a/plots/residual-plot/implementations/pygal.py
+++ b/plots/residual-plot/implementations/pygal.py
@@ -1,7 +1,7 @@
-"""pyplots.ai
+""" pyplots.ai
 residual-plot: Residual Plot
 Library: pygal 3.1.0 | Python 3.13.11
-Quality: 85/100 | Created: 2025-12-26
+Quality: 88/100 | Created: 2025-12-26
 """
 
 import numpy as np
diff --git a/plots/residual-plot/metadata/pygal.yaml b/plots/residual-plot/metadata/pygal.yaml
index db4bdc7301..733f1c5cca 100644
--- a/plots/residual-plot/metadata/pygal.yaml
+++ b/plots/residual-plot/metadata/pygal.yaml
@@ -1,7 +1,7 @@
 library: pygal
 specification_id: residual-plot
 created: '2025-12-26T19:35:50Z'
-updated: '2025-12-26T19:53:58Z'
+updated: '2025-12-26T19:59:17Z'
 generated_by: claude-opus-4-5-20251101
 workflow_run: 20528206404
 issue: 0
@@ -10,15 +10,18 @@ library_version: 3.1.0
 preview_url: https://storage.googleapis.com/pyplots-images/plots/residual-plot/pygal/plot.png
 preview_thumb: https://storage.googleapis.com/pyplots-images/plots/residual-plot/pygal/plot_thumb.png
 preview_html: https://storage.googleapis.com/pyplots-images/plots/residual-plot/pygal/plot.html
-quality_score: 85
+quality_score: 88
 review:
   strengths:
-  - 'Excellent implementation of all spec requirements: zero reference line, ±2σ threshold
-    bands, and outlier highlighting in different color'
-  - Realistic house price prediction context with appropriate heteroscedasticity pattern
-  - Clean code structure following KISS principles with proper random seed
-  - Good use of pygal XY chart with custom styling for high-resolution output
-  - Proper axis labels with units and correct title format
+  - Excellent implementation of all spec requirements including zero reference line,
+    ±2σ threshold bands, and outlier highlighting
+  - Clean separation of normal points (blue) and outliers (red) using color differentiation
+  - Realistic house price prediction scenario with appropriate heteroscedasticity
+    pattern
+  - Good use of pygal XY chart with custom styling and stroke patterns for reference
+    lines
+  - Correct title format and descriptive axis labels with units
   weaknesses:
-  - Legend text at bottom is too small to read clearly at the rendered scale
-  - Grid guides could be more subtle (lower alpha) for better visual balance
+  - Legend text at bottom is too small to read clearly at the rendered size
+  - Axis tick label font size could be larger for better readability on the 4800x2700
+    canvas