update(area-basic): pygal — comprehensive quality review (#4177)

## Summary

Updated **pygal** implementation for **area-basic**.

### Changes
- Added tooltip font sizing and value formatter with comma separation
- Increased dot size from 6 to 8 for better visibility
- Improved y-axis label with units "(per day)"
- Fixed title encoding for middle dot character

## Test Plan

- [x] Preview images uploaded to GCS staging
- [x] Implementation file passes ruff format/check
- [x] Metadata YAML updated with current versions
- [ ] Automated review triggered

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

---------

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: MarkusNeusinger

plots/area-basic/implementations/pygal.py

@@ -1,7 +1,7 @@
 """ pyplots.ai
 area-basic: Basic Area Chart
-Library: pygal 3.1.0 | Python 3.13.11
-Quality: 91/100 | Created: 2025-12-23
+Library: pygal 3.1.0 | Python 3.14.2
+Quality: 94/100 | Created: 2025-12-23
 """
 
 import pygal
@@ -56,6 +56,7 @@
     major_label_font_size=42,
     legend_font_size=42,
     value_font_size=36,
+    tooltip_font_size=36,
     opacity=0.4,
     opacity_hover=0.6,
 )
@@ -64,19 +65,20 @@
 chart = pygal.Line(
     width=4800,
     height=2700,
-    title="area-basic · pygal · pyplots.ai",
+    title="area-basic \u00b7 pygal \u00b7 pyplots.ai",
     x_title="Day of Month",
-    y_title="Visitors",
+    y_title="Visitors (per day)",
     style=custom_style,
     fill=True,
     show_dots=True,
-    dots_size=6,
+    dots_size=8,
     stroke_style={"width": 4},
     show_y_guides=True,
     show_x_guides=False,
     x_label_rotation=0,
     legend_at_bottom=True,
     truncate_legend=-1,
+    value_formatter=lambda x: f"{x:,.0f}",
 )
 
 # Add data - show every 5th day label for readability

plots/area-basic/metadata/pygal.yaml

@@ -1,180 +1,185 @@
 library: pygal
 specification_id: area-basic
 created: '2025-12-23T00:48:44Z'
-updated: '2025-12-23T01:22:10Z'
-generated_by: claude-opus-4-5-20251101
+updated: '2026-02-11T22:27:40Z'
+generated_by: claude-opus-4-6
 workflow_run: 20447989472
 issue: 0
-python_version: 3.13.11
+python_version: 3.14.2
 library_version: 3.1.0
 preview_url: https://storage.googleapis.com/pyplots-images/plots/area-basic/pygal/plot.png
 preview_thumb: https://storage.googleapis.com/pyplots-images/plots/area-basic/pygal/plot_thumb.png
 preview_html: https://storage.googleapis.com/pyplots-images/plots/area-basic/pygal/plot.html
-quality_score: 91
+quality_score: 94
 impl_tags:
   dependencies: []
-  techniques: []
+  techniques:
+  - html-export
   patterns: []
   dataprep: []
   styling:
-    - alpha-blending
+  - alpha-blending
+  - grid-styling
 review:
   strengths:
-  - Excellent implementation of the area chart concept with proper fill transparency
-    (0.4 opacity)
-  - Clean, well-structured code following KISS principles
-  - Realistic website traffic data with clear weekly patterns (weekend dips, weekday
-    peaks)
-  - Smart X-axis label strategy showing only every 5th day to prevent clutter
-  - Correct title format and proper canvas sizing (4800x2700)
-  - Good use of pygal Style class for consistent theming
+  - Clean, well-structured code following KISS principle with hardcoded deterministic
+    data
+  - Excellent use of pygal Style class for comprehensive visual customization
+  - Smart x-label spacing (every 5th day) preventing overlap while maintaining readability
+  - Appropriate semi-transparent fill (opacity=0.4) matching spec recommendations
+  - Dual output (HTML for interactivity + PNG for static) leveraging pygal native
+    SVG capabilities
+  - Realistic, neutral data scenario with natural weekly patterns in website traffic
   weaknesses:
-  - Y-axis label Visitors could include units (e.g., Visitors count)
-  - Data dots could be slightly larger for better visibility at the target resolution
-  - Could leverage more pygal-specific features like custom tooltips or value formatting
-  image_description: The plot displays a basic area chart with a light blue/steel
-    blue filled area beneath the line. The title "area-basic · pygal · pyplots.ai"
-    is clearly visible at the top. The X-axis is labeled "Day of Month" with values
-    1, 5, 10, 15, 20, 25, 30 shown. The Y-axis is labeled "Visitors" with values ranging
-    from approximately 900 to 2100. Data points are marked with small dots along the
-    line. The area fill has semi-transparency (approximately 40% opacity). A legend
-    "Daily Visitors" appears at the bottom left. The background is white with subtle
-    horizontal gridlines. The chart shows website traffic patterns with weekend dips
-    and weekday peaks.
+  - Font sizes in the custom style (72, 48, 42) are significantly larger than the
+    library guide recommendations (28, 18, 16) — while the output looks good, it deviates
+    from the standard pygal style template
+  - Dots could be slightly larger (dots_size=8 is modest for a 4800x2700 canvas) to
+    improve data point visibility
+  - No gradient fill effect was attempted, even though the spec suggests considering
+    it for visual appeal
+  image_description: The plot displays a basic area chart on a white background. A
+    single blue-filled area (#306998) with semi-transparent fill (opacity ~0.4) shows
+    daily website visitors over 30 days. Blue dots mark each of the 30 data points
+    along the line. The Y-axis is labeled "Visitors (per day)" ranging from ~900 to
+    ~2,150 with comma-formatted tick labels and horizontal dashed gridlines. The X-axis
+    is labeled "Day of Month" with labels shown at days 1, 5, 10, 15, 20, 25, and
+    30 for readability. The title "area-basic · pygal · pyplots.ai" is centered at
+    the top in gray text. A small legend reading "Daily Visitors" appears at the bottom
+    left. The data shows a clear upward trend with weekly cycling patterns (dips around
+    days 5-7, 13-14, 19-21, 27-28), effectively demonstrating the area chart's strength
+    at conveying volume and magnitude over time.
   criteria_checklist:
     visual_quality:
-      score: 36
+      score: 37
       max: 40
       items:
       - id: VQ-01
         name: Text Legibility
         score: 9
         max: 10
         passed: true
-        comment: Title, axis labels, and tick marks are all readable. Font sizes are
-          well-scaled for the 4800x2700 canvas.
+        comment: All text clearly readable at full size. Title, axis labels, and tick
+          labels well-proportioned for 4800x2700 canvas.
       - id: VQ-02
         name: No Overlap
         score: 8
         max: 8
         passed: true
-        comment: No overlapping text elements. X-axis labels are spaced well by showing
-          every 5th day.
+        comment: No overlapping text. X-axis labels intelligently spaced every 5th
+          day.
       - id: VQ-03
         name: Element Visibility
         score: 7
         max: 8
         passed: true
-        comment: Line and fill are clearly visible. Dots are appropriately sized at
-          6px. Could be slightly larger for better visibility.
+        comment: Data points and area fill well-defined. Dots could be marginally
+          larger for the canvas size.
       - id: VQ-04
         name: Color Accessibility
         score: 5
         max: 5
         passed: true
-        comment: Single color scheme (#306998 blue) is colorblind-safe.
+        comment: Single blue color scheme is fully colorblind-safe with good contrast.
       - id: VQ-05
         name: Layout Balance
-        score: 5
+        score: 4
         max: 5
         passed: true
-        comment: Good proportions with legend at bottom, proper margins.
+        comment: Good proportions overall. Minor space at bottom with legend could
+          be more compact.
       - id: VQ-06
         name: Axis Labels
-        score: 1
+        score: 2
         max: 2
         passed: true
-        comment: Labels are descriptive ("Day of Month", "Visitors") but "Visitors"
-          lacks units (e.g., "count" or "per day").
+        comment: 'Descriptive labels with units: Day of Month, Visitors (per day).'
       - id: VQ-07
         name: Grid & Legend
-        score: 1
+        score: 2
         max: 2
         passed: true
-        comment: Y-axis gridlines are subtle and helpful. Legend placement is good
-          but could be more prominent.
+        comment: Subtle horizontal gridlines, legend well-placed at bottom.
     spec_compliance:
-      score: 25
+      score: 24
       max: 25
       items:
       - id: SC-01
         name: Plot Type
         score: 8
         max: 8
         passed: true
-        comment: Correct area chart type using pygal.Line with fill=True.
+        comment: Correct area chart using pygal.Line with fill=True.
       - id: SC-02
         name: Data Mapping
         score: 5
         max: 5
         passed: true
-        comment: X (days) and Y (visitors) correctly assigned.
+        comment: X=days (continuous), Y=visitors (magnitude). Correctly assigned.
       - id: SC-03
         name: Required Features
-        score: 5
+        score: 4
         max: 5
         passed: true
-        comment: Semi-transparent fill (0.4), gridlines, clear axis labels all present.
+        comment: Semi-transparent fill, gridlines, clear axis labels with units. No
+          gradient fill attempted.
       - id: SC-04
         name: Data Range
         score: 3
         max: 3
         passed: true
-        comment: All 30 days visible, Y-axis shows full range from ~890 to ~2150.
+        comment: All data points visible, axes auto-scaled to full range.
       - id: SC-05
         name: Legend Accuracy
         score: 2
         max: 2
         passed: true
-        comment: Legend correctly shows "Daily Visitors".
+        comment: Daily Visitors legend label is accurate.
       - id: SC-06
         name: Title Format
         score: 2
         max: 2
         passed: true
-        comment: 'Correct format: "area-basic · pygal · pyplots.ai".'
+        comment: 'Correct format: area-basic · pygal · pyplots.ai.'
     data_quality:
-      score: 18
+      score: 19
       max: 20
       items:
       - id: DQ-01
         name: Feature Coverage
         score: 7
         max: 8
         passed: true
-        comment: Shows trends, peaks, valleys, and weekly patterns. Could show more
-          dramatic variation.
+        comment: Shows upward trend, weekly cycles, magnitude variation. Good demonstration
+          of area chart strengths.
       - id: DQ-02
         name: Realistic Context
         score: 7
         max: 7
         passed: true
-        comment: Website visitor data over a month is a perfect real-world scenario
-          matching the spec example.
+        comment: Daily website visitors over a month - neutral, real-world scenario.
       - id: DQ-03
         name: Appropriate Scale
-        score: 4
+        score: 5
         max: 5
         passed: true
-        comment: Values (890-2150 visitors) are realistic for a small-medium website.
-          Range is reasonable.
+        comment: Values 890-2150 are realistic for a small-to-medium website.
     code_quality:
-      score: 9
+      score: 10
       max: 10
       items:
       - id: CQ-01
         name: KISS Structure
         score: 3
         max: 3
         passed: true
-        comment: 'Clean script: imports → data → plot → save. No functions or classes.'
+        comment: Clean Imports → Data → Style → Chart → Save structure.
       - id: CQ-02
         name: Reproducibility
-        score: 2
+        score: 3
         max: 3
         passed: true
-        comment: Data is deterministic (hardcoded list), but no random seed comment
-          explaining this.
+        comment: All data hardcoded, fully deterministic.
       - id: CQ-03
         name: Clean Imports
         score: 2
@@ -186,23 +191,22 @@ review:
         score: 1
         max: 1
         passed: true
-        comment: Using current pygal API.
+        comment: Uses current pygal API.
       - id: CQ-05
         name: Output Correct
         score: 1
         max: 1
         passed: true
-        comment: Saves as plot.png and plot.html.
+        comment: Saves as plot.png.
     library_features:
-      score: 3
+      score: 4
       max: 5
       items:
       - id: LF-01
-        name: Uses distinctive library features
-        score: 3
+        name: Distinctive Features
+        score: 4
         max: 5
         passed: true
-        comment: Uses pygal's Style class for customization, fill=True for area, show_dots,
-          stroke_style. Could leverage more pygal-specific features like tooltips
-          or value formatters.
+        comment: Good use of Style class, fill=True, show_dots, stroke_style, value_formatter,
+          dual HTML+PNG output.
   verdict: APPROVED