From 62e7a1539c507deab7ada82bdc208fc173f5f88e Mon Sep 17 00:00:00 2001
From: Markus Neusinger <2921697+MarkusNeusinger@users.noreply.github.com>
Date: Mon, 23 Feb 2026 22:29:16 +0100
Subject: [PATCH 1/8] =?UTF-8?q?update(arc-basic):=20letsplot=20=E2=80=94?=
 =?UTF-8?q?=20comprehensive=20quality=20review?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Comprehensive review and update of letsplot implementation for arc-basic.
---
 plots/arc-basic/implementations/letsplot.py | 107 +++++++++++++++-----
 plots/arc-basic/metadata/letsplot.yaml      |   8 +-
 2 files changed, 83 insertions(+), 32 deletions(-)

diff --git a/plots/arc-basic/implementations/letsplot.py b/plots/arc-basic/implementations/letsplot.py
index 168fe2f8f5..0cc7fd1dea 100644
--- a/plots/arc-basic/implementations/letsplot.py
+++ b/plots/arc-basic/implementations/letsplot.py
@@ -1,7 +1,7 @@
-""" pyplots.ai
+"""pyplots.ai
 arc-basic: Basic Arc Diagram
-Library: letsplot 4.8.2 | Python 3.13.11
-Quality: 92/100 | Created: 2025-12-23
+Library: letsplot 4.8.2 | Python 3.14.3
+Quality: /100 | Updated: 2026-02-23
 """
 
 import numpy as np
@@ -10,13 +10,18 @@
     LetsPlot,
     aes,
     element_blank,
+    element_rect,
     element_text,
     geom_path,
     geom_point,
+    geom_segment,
     geom_text,
     ggplot,
     ggsize,
     labs,
+    layer_tooltips,
+    scale_alpha_identity,
+    scale_color_identity,
     scale_size_identity,
     theme,
     xlim,
@@ -28,14 +33,12 @@
 LetsPlot.setup_html()
 
 # Data: Character interactions in a story chapter
-np.random.seed(42)
-
 nodes = ["Alice", "Bob", "Carol", "David", "Eve", "Frank", "Grace", "Henry", "Iris", "Jack"]
 n_nodes = len(nodes)
 
 # Edges: pairs of connected nodes with weights (source, target, weight)
 edges = [
-    (0, 1, 3),  # Alice-Bob (strong connection)
+    (0, 1, 3),  # Alice-Bob (strong)
     (0, 3, 2),  # Alice-David
     (1, 2, 2),  # Bob-Carol
     (2, 4, 1),  # Carol-Eve
@@ -54,7 +57,18 @@
 
 # Node positions along x-axis
 x_positions = np.linspace(0, 1, n_nodes)
-y_baseline = 0.1
+y_baseline = 0.08
+
+# Count connections per node for visual hierarchy
+connections = [0] * n_nodes
+for s, t, w in edges:
+    connections[s] += w
+    connections[t] += w
+
+# Arc color intensity by weight
+weight_colors = {1: "#93B8CC", 2: "#306998", 3: "#1A3A5C"}
+weight_alphas = {1: 0.5, 2: 0.65, 3: 0.8}
+weight_labels = {1: "Weak", 2: "Moderate", 3: "Strong"}
 
 # Create arc data for geom_path
 arc_data = []
@@ -66,57 +80,94 @@
     distance = abs(end - start)
     height = 0.08 * distance
 
-    # Generate points along the arc (semi-circle)
+    # Generate points along the arc
     n_points = 50
     t = np.linspace(0, np.pi, n_points)
     arc_x = x_start + (x_end - x_start) * (1 - np.cos(t)) / 2
     arc_y = y_baseline + height * np.sin(t)
 
-    # Line width based on weight
-    line_size = 1.5 + weight * 1.0
+    line_size = 1.0 + weight * 1.2
+    color = weight_colors[weight]
+    alpha = weight_alphas[weight]
+    tooltip_text = f"{nodes[start]} \u2194 {nodes[end]}"
+    strength = weight_labels[weight]
 
     for i in range(n_points):
-        arc_data.append({"x": arc_x[i], "y": arc_y[i], "edge_id": edge_id, "weight": weight, "size": line_size})
+        arc_data.append(
+            {
+                "x": arc_x[i],
+                "y": arc_y[i],
+                "edge_id": edge_id,
+                "size": line_size,
+                "color": color,
+                "alpha": alpha,
+                "connection": tooltip_text,
+                "strength": strength,
+            }
+        )
 
 arc_df = pd.DataFrame(arc_data)
 
-# Node data
-node_df = pd.DataFrame({"x": x_positions, "y": [y_baseline] * n_nodes, "name": nodes})
+# Node data with size based on total connection weight
+max_conn = max(connections)
+node_sizes = [6 + 10 * (c / max_conn) for c in connections]
+node_df = pd.DataFrame(
+    {"x": x_positions, "y": [y_baseline] * n_nodes, "name": nodes, "node_size": node_sizes, "connections": connections}
+)
+
+# Baseline segment data
+baseline_df = pd.DataFrame({"x": [x_positions[0]], "xend": [x_positions[-1]], "y": [y_baseline], "yend": [y_baseline]})
 
 # Label data (positioned below nodes)
-label_df = pd.DataFrame({"x": x_positions, "y": [y_baseline - 0.05] * n_nodes, "name": nodes})
+label_df = pd.DataFrame({"x": x_positions, "y": [y_baseline - 0.045] * n_nodes, "name": nodes})
 
-# Create plot
+# Plot
 plot = (
     ggplot()
-    # Draw arcs with semi-transparency for overlapping connections
-    + geom_path(data=arc_df, mapping=aes(x="x", y="y", group="edge_id", size="size"), color="#306998", alpha=0.6)
+    # Subtle baseline
+    + geom_segment(data=baseline_df, mapping=aes(x="x", y="y", xend="xend", yend="yend"), color="#D0D8E0", size=0.8)
+    # Arcs with weight-based color, transparency, and tooltips
+    + geom_path(
+        data=arc_df,
+        mapping=aes(x="x", y="y", group="edge_id", size="size", color="color", alpha="alpha"),
+        tooltips=layer_tooltips().line("@connection").line("Strength: @strength"),
+    )
+    + scale_size_identity()
+    + scale_color_identity()
+    + scale_alpha_identity()
+    # Nodes sized by connection weight with tooltips
+    + geom_point(
+        data=node_df,
+        mapping=aes(x="x", y="y", size="node_size"),
+        color="#1A3A5C",
+        fill="#FFD43B",
+        stroke=1.5,
+        shape=21,
+        tooltips=layer_tooltips().line("@name").line("Connections: @connections"),
+    )
     + scale_size_identity()
-    # Draw nodes
-    + geom_point(data=node_df, mapping=aes(x="x", y="y"), size=10, color="#FFD43B", fill="#FFD43B", stroke=2, shape=21)
-    # Add node labels
+    # Node labels
     + geom_text(
-        data=label_df, mapping=aes(x="x", y="y", label="name"), size=14, color="#306998", fontface="bold", vjust=1
+        data=label_df, mapping=aes(x="x", y="y", label="name"), size=16, color="#1A3A5C", fontface="bold", vjust=1
     )
     # Styling
-    + xlim(-0.05, 1.05)
+    + xlim(-0.06, 1.06)
     + ylim(-0.15, 0.85)
-    + labs(title="Character Interactions · arc-basic · letsplot · pyplots.ai")
+    + labs(title="Character Interactions \u00b7 arc-basic \u00b7 letsplot \u00b7 pyplots.ai")
     + theme(
         axis_title=element_blank(),
         axis_text=element_blank(),
         axis_ticks=element_blank(),
         axis_line=element_blank(),
         panel_grid=element_blank(),
-        panel_background=element_blank(),
-        plot_title=element_text(size=24, face="bold"),
+        panel_background=element_rect(fill="white", color="white"),
+        plot_background=element_rect(fill="white", color="white"),
+        plot_title=element_text(size=24, face="bold", color="#1A3A5C"),
         legend_position="none",
     )
     + ggsize(1600, 900)
 )
 
-# Save as PNG (scale 3x to get 4800 x 2700 px)
+# Save
 ggsave(plot, "plot.png", path=".", scale=3)
-
-# Save as HTML for interactive viewing
 ggsave(plot, "plot.html", path=".")
diff --git a/plots/arc-basic/metadata/letsplot.yaml b/plots/arc-basic/metadata/letsplot.yaml
index cdce9fd1cb..0c2b7bb2fe 100644
--- a/plots/arc-basic/metadata/letsplot.yaml
+++ b/plots/arc-basic/metadata/letsplot.yaml
@@ -1,16 +1,16 @@
 library: letsplot
 specification_id: arc-basic
 created: '2025-12-23T08:49:14Z'
-updated: '2025-12-23T09:04:29Z'
-generated_by: claude-opus-4-5-20251101
+updated: '2026-02-23T12:00:00+00:00'
+generated_by: claude-opus-4-6
 workflow_run: 20455965726
 issue: 0
-python_version: 3.13.11
+python_version: '3.14.3'
 library_version: 4.8.2
 preview_url: https://storage.googleapis.com/pyplots-images/plots/arc-basic/letsplot/plot.png
 preview_thumb: https://storage.googleapis.com/pyplots-images/plots/arc-basic/letsplot/plot_thumb.png
 preview_html: https://storage.googleapis.com/pyplots-images/plots/arc-basic/letsplot/plot.html
-quality_score: 92
+quality_score: null
 impl_tags:
   dependencies: []
   techniques:

From cc5afceee3f298baafe37c2ee4b24d03820a7e2e Mon Sep 17 00:00:00 2001
From: "github-actions[bot]" <github-actions[bot]@users.noreply.github.com>
Date: Mon, 23 Feb 2026 21:34:49 +0000
Subject: [PATCH 2/8] chore(letsplot): update quality score 87 and review
 feedback for arc-basic

---
 plots/arc-basic/implementations/letsplot.py |   4 +-
 plots/arc-basic/metadata/letsplot.yaml      | 268 ++++++++++----------
 2 files changed, 143 insertions(+), 129 deletions(-)

diff --git a/plots/arc-basic/implementations/letsplot.py b/plots/arc-basic/implementations/letsplot.py
index 0cc7fd1dea..18403f9933 100644
--- a/plots/arc-basic/implementations/letsplot.py
+++ b/plots/arc-basic/implementations/letsplot.py
@@ -1,7 +1,7 @@
-"""pyplots.ai
+""" pyplots.ai
 arc-basic: Basic Arc Diagram
 Library: letsplot 4.8.2 | Python 3.14.3
-Quality: /100 | Updated: 2026-02-23
+Quality: 87/100 | Updated: 2026-02-23
 """
 
 import numpy as np
diff --git a/plots/arc-basic/metadata/letsplot.yaml b/plots/arc-basic/metadata/letsplot.yaml
index 0c2b7bb2fe..1de3fd31e2 100644
--- a/plots/arc-basic/metadata/letsplot.yaml
+++ b/plots/arc-basic/metadata/letsplot.yaml
@@ -1,179 +1,188 @@
 library: letsplot
 specification_id: arc-basic
 created: '2025-12-23T08:49:14Z'
-updated: '2026-02-23T12:00:00+00:00'
+updated: '2026-02-23T21:34:49Z'
 generated_by: claude-opus-4-6
 workflow_run: 20455965726
 issue: 0
-python_version: '3.14.3'
+python_version: 3.14.3
 library_version: 4.8.2
 preview_url: https://storage.googleapis.com/pyplots-images/plots/arc-basic/letsplot/plot.png
 preview_thumb: https://storage.googleapis.com/pyplots-images/plots/arc-basic/letsplot/plot_thumb.png
 preview_html: https://storage.googleapis.com/pyplots-images/plots/arc-basic/letsplot/plot.html
-quality_score: null
+quality_score: 87
 impl_tags:
   dependencies: []
   techniques:
   - layer-composition
+  - hover-tooltips
   - html-export
   patterns:
   - data-generation
   - iteration-over-groups
-  - matrix-construction
   dataprep: []
   styling:
+  - minimal-chrome
   - alpha-blending
+  - edge-highlighting
 review:
   strengths:
-  - Excellent visual design with clear proportional arc heights showing connection
-    distances
-  - Smart use of semi-transparency (alpha=0.6) for overlapping arcs
-  - Weight-based line thickness provides additional dimension
-  - Clean minimalist styling with hidden axes appropriate for arc diagrams
-  - Realistic character interaction scenario matches spec applications
-  - Well-structured code following KISS principles
+  - Clean cohesive blue monochromatic palette with yellow node accents creating effective
+    visual contrast
+  - 'Correct visual hierarchy: node size by connection weight, arc thickness/color/height
+    by edge weight'
+  - Comprehensive data covering all arc diagram features (short/long-range, varied
+    weights, overlapping arcs)
+  - Interactive tooltips via layer_tooltips showing connection details and strength
+  - Well-structured deterministic code with clean minimal chrome (all spines/axes/grid
+    removed)
   weaknesses:
-  - Node labels could be slightly larger for optimal readability at high resolution
-  - Does not leverage lets-plot specific interactive features (could use tooltips
-    on hover)
-  image_description: The plot displays a well-executed arc diagram visualizing character
-    interactions. Ten nodes (Alice, Bob, Carol, David, Eve, Frank, Grace, Henry, Iris,
-    Jack) are arranged horizontally along a baseline, represented as yellow circular
-    markers. Blue semi-transparent arcs curve above the baseline connecting related
-    characters. Arc heights are proportional to the distance between connected nodes
-    - short-range connections (like Alice-Bob) have low arcs while long-range connections
-    (like Alice-Jack) have tall arcs spanning nearly the full width. Arc thickness
-    varies based on connection weight, with stronger connections appearing thicker.
-    The title "Character Interactions · arc-basic · letsplot · pyplots.ai" appears
-    at the top left in bold. Node labels are displayed below each node in bold blue
-    text. The design uses a clean white background with no axis lines or grid.
+  - Title format includes non-standard prefix before required spec-id format, no weight
+    legend
+  - Weight-1 arcs are faint (alpha=0.5 with light blue) reducing visibility
+  - Wasted vertical space below node labels (ylim extends too far)
+  - Node label font size (16pt) could be larger for optimal readability at full resolution
+  image_description: 'The plot displays a basic arc diagram with 10 character nodes
+    (Alice, Bob, Carol, David, Eve, Frank, Grace, Henry, Iris, Jack) arranged along
+    a horizontal baseline from left to right. Each node is rendered as a yellow circle
+    (#FFD43B) with a dark blue (#1A3A5C) outline, with sizes varying by total connection
+    weight — Alice and David are the largest. Arcs connect node pairs above the baseline
+    using a blue monochromatic palette: light blue (#93B8CC, alpha 0.5) for weight-1
+    connections, medium blue (#306998, alpha 0.65) for weight-2, and dark blue (#1A3A5C,
+    alpha 0.8) for weight-3. Arc height is proportional to the distance between connected
+    nodes — the Alice-Jack arc spans the full width and reaches the highest point.
+    Arc thickness also scales with weight. A subtle gray baseline connects all nodes.
+    Node labels appear in bold dark blue text below the baseline. The title "Character
+    Interactions · arc-basic · letsplot · pyplots.ai" is positioned in the upper left
+    in bold dark blue. The background is clean white with no axes, spines, or grid
+    lines.'
   criteria_checklist:
     visual_quality:
-      score: 36
-      max: 40
+      score: 27
+      max: 30
       items:
       - id: VQ-01
         name: Text Legibility
-        score: 9
-        max: 10
+        score: 7
+        max: 8
         passed: true
-        comment: Title and labels are clearly readable. Font sizes are appropriate
-          for the output resolution. Labels could be slightly larger for optimal readability.
+        comment: Title explicitly set to 24pt, node labels to 16pt bold. All readable;
+          labels could be slightly larger (18-20pt).
       - id: VQ-02
         name: No Overlap
-        score: 8
-        max: 8
+        score: 6
+        max: 6
         passed: true
-        comment: No overlapping text elements. Node labels are well-spaced and arcs
-          do not obscure labels.
+        comment: No overlapping text or elements. Labels well-spaced below baseline,
+          arcs above.
       - id: VQ-03
         name: Element Visibility
-        score: 7
-        max: 8
+        score: 5
+        max: 6
         passed: true
-        comment: Nodes are clearly visible with good sizing. Arcs use appropriate
-          alpha (0.6) for overlapping connections. Some thinner arcs could be slightly
-          more visible.
+        comment: Most elements well-sized. Weight-1 arcs (alpha=0.5, light blue) are
+          somewhat faint. Smaller nodes appear small.
       - id: VQ-04
         name: Color Accessibility
-        score: 5
-        max: 5
+        score: 4
+        max: 4
         passed: true
-        comment: Blue (#306998) and yellow (#FFD43B) provide excellent contrast. Colorblind-safe
-          combination.
+        comment: Blue monochromatic scheme with yellow accents. Fully colorblind-safe.
       - id: VQ-05
-        name: Layout Balance
-        score: 5
-        max: 5
+        name: Layout & Canvas
+        score: 3
+        max: 4
         passed: true
-        comment: Excellent use of canvas space. Arcs fill the upper portion well,
-          nodes centered horizontally.
+        comment: Good horizontal utilization. Some wasted vertical space below node
+          labels.
       - id: VQ-06
-        name: Axis Labels
-        score: 0
-        max: 2
-        passed: true
-        comment: N/A for arc diagrams (axes are hidden by design), but no descriptive
-          subtitle or legend explaining the visualization.
-      - id: VQ-07
-        name: Grid & Legend
+        name: Axis Labels & Title
         score: 2
         max: 2
         passed: true
-        comment: Appropriately no grid for this diagram type. Legend hidden as connection
-          weights are shown via line thickness.
+        comment: Descriptive title present. Axes appropriately hidden for arc diagram.
+    design_excellence:
+      score: 14
+      max: 20
+      items:
+      - id: DE-01
+        name: Aesthetic Sophistication
+        score: 5
+        max: 8
+        passed: true
+        comment: Custom cohesive blue palette with yellow node accents, intentional
+          color hierarchy by weight. Above defaults but not publication-level.
+      - id: DE-02
+        name: Visual Refinement
+        score: 5
+        max: 6
+        passed: true
+        comment: All spines, axes, and grid removed. Clean white background. Subtle
+          gray baseline. Well-polished minimal chrome.
+      - id: DE-03
+        name: Data Storytelling
+        score: 4
+        max: 6
+        passed: true
+        comment: Visual hierarchy through node size, arc thickness/color, and arc
+          height. Alice and David naturally stand out.
     spec_compliance:
-      score: 24
-      max: 25
+      score: 14
+      max: 15
       items:
       - id: SC-01
         name: Plot Type
-        score: 8
-        max: 8
-        passed: true
-        comment: Correct arc diagram implementation with nodes on horizontal axis
-          and curved arcs above.
-      - id: SC-02
-        name: Data Mapping
         score: 5
         max: 5
         passed: true
-        comment: Nodes correctly positioned, edges correctly drawn between specified
-          pairs.
-      - id: SC-03
+        comment: Correct arc diagram with nodes on horizontal line and curved arcs
+          above, height proportional to node distance.
+      - id: SC-02
         name: Required Features
-        score: 5
-        max: 5
+        score: 4
+        max: 4
         passed: true
-        comment: 'All spec features present: arc height proportional to distance,
-          semi-transparent overlapping arcs, readable node labels, weight-based line
-          thickness.'
-      - id: SC-04
-        name: Data Range
+        comment: 'All spec features present: arcs, weight-based thickness/color, semi-transparency,
+          readable labels, proportional arc height.'
+      - id: SC-03
+        name: Data Mapping
         score: 3
         max: 3
         passed: true
-        comment: All nodes and connections visible within the plot area.
-      - id: SC-05
-        name: Legend Accuracy
-        score: 1
-        max: 2
-        passed: true
-        comment: No explicit legend for weights, but thickness variation is intuitive.
-          Could benefit from a brief explanation.
-      - id: SC-06
-        name: Title Format
+        comment: 10 nodes correctly positioned, 15 edges correctly mapped with proper
+          weight encoding.
+      - id: SC-04
+        name: Title & Legend
         score: 2
-        max: 2
-        passed: true
-        comment: 'Title follows exact format: "Character Interactions · arc-basic
-          · letsplot · pyplots.ai"'
+        max: 3
+        passed: false
+        comment: Title adds non-standard prefix before required format. No weight
+          legend.
     data_quality:
-      score: 19
-      max: 20
+      score: 15
+      max: 15
       items:
       - id: DQ-01
         name: Feature Coverage
-        score: 7
-        max: 8
+        score: 6
+        max: 6
         passed: true
-        comment: Shows both short-range and long-range connections, varying weights
-          (1-3), multiple connections per node. Could include isolated node to show
-          full feature range.
+        comment: Shows short/long-range connections, three weight levels, overlapping
+          arcs, varied node connectivity.
       - id: DQ-02
         name: Realistic Context
-        score: 7
-        max: 7
+        score: 5
+        max: 5
         passed: true
-        comment: Character interactions in a story chapter is a perfect real-world
-          application matching the spec's narrative flow example.
+        comment: Character interactions in a story chapter — real, neutral, comprehensible
+          scenario.
       - id: DQ-03
         name: Appropriate Scale
-        score: 5
-        max: 5
+        score: 4
+        max: 4
         passed: true
-        comment: 10 nodes with 15 edges is appropriate scale for readability as per
-          spec (10-50 nodes typical).
+        comment: 10 nodes in recommended range, 15 edges at reasonable density, weights
+          1-3.
     code_quality:
       score: 10
       max: 10
@@ -183,42 +192,47 @@ review:
         score: 3
         max: 3
         passed: true
-        comment: 'Clean linear structure: imports → data → arc generation → plot →
-          save. No unnecessary functions or classes.'
+        comment: 'Flat script: imports, data, plot, save. No functions or classes.'
       - id: CQ-02
         name: Reproducibility
-        score: 3
-        max: 3
+        score: 2
+        max: 2
         passed: true
-        comment: Uses `np.random.seed(42)` for reproducibility.
+        comment: All data is deterministic (hard-coded nodes, edges, weights).
       - id: CQ-03
         name: Clean Imports
         score: 2
         max: 2
         passed: true
-        comment: All imports are used. Explicit imports from lets_plot.
+        comment: All imports are used; no unused imports.
       - id: CQ-04
-        name: No Deprecated API
-        score: 1
-        max: 1
+        name: Code Elegance
+        score: 2
+        max: 2
         passed: true
-        comment: Uses current lets-plot API.
+        comment: Well-structured, readable code with appropriate complexity.
       - id: CQ-05
-        name: Output Correct
+        name: Output & API
         score: 1
         max: 1
         passed: true
-        comment: Saves as `plot.png` and `plot.html`.
-    library_features:
-      score: 3
-      max: 5
+        comment: Saves as plot.png with scale=3. Current lets_plot API.
+    library_mastery:
+      score: 7
+      max: 10
       items:
-      - id: LF-01
+      - id: LM-01
+        name: Idiomatic Usage
+        score: 4
+        max: 5
+        passed: true
+        comment: Good grammar-of-graphics usage with layered geoms, aes mappings,
+          scale_*_identity(), theme customization.
+      - id: LM-02
         name: Distinctive Features
         score: 3
         max: 5
         passed: true
-        comment: Uses ggplot2 grammar correctly with geom_path, geom_point, geom_text,
-          and scale_size_identity. However, does not leverage any lets-plot specific
-          interactive features or advanced capabilities beyond basic ggplot2 syntax.
-  verdict: APPROVED
+        comment: Uses layer_tooltips() for hover information and HTML export via ggsave
+          — distinctive letsplot features.
+  verdict: REJECTED

From fdf183825e4a86692ec37c4c30745c648da688cb Mon Sep 17 00:00:00 2001
From: "github-actions[bot]" <github-actions[bot]@users.noreply.github.com>
Date: Mon, 23 Feb 2026 21:39:40 +0000
Subject: [PATCH 3/8] fix(letsplot): address review feedback for arc-basic

Attempt 1/3 - fixes based on AI review
---
 plots/arc-basic/implementations/letsplot.py | 43 ++++++++++++++++++---
 1 file changed, 37 insertions(+), 6 deletions(-)

diff --git a/plots/arc-basic/implementations/letsplot.py b/plots/arc-basic/implementations/letsplot.py
index 18403f9933..470b6d3a15 100644
--- a/plots/arc-basic/implementations/letsplot.py
+++ b/plots/arc-basic/implementations/letsplot.py
@@ -1,4 +1,4 @@
-""" pyplots.ai
+"""pyplots.ai
 arc-basic: Basic Arc Diagram
 Library: letsplot 4.8.2 | Python 3.14.3
 Quality: 87/100 | Updated: 2026-02-23
@@ -66,8 +66,8 @@
     connections[t] += w
 
 # Arc color intensity by weight
-weight_colors = {1: "#93B8CC", 2: "#306998", 3: "#1A3A5C"}
-weight_alphas = {1: 0.5, 2: 0.65, 3: 0.8}
+weight_colors = {1: "#7FAABB", 2: "#306998", 3: "#1A3A5C"}
+weight_alphas = {1: 0.6, 2: 0.7, 3: 0.85}
 weight_labels = {1: "Weak", 2: "Moderate", 3: "Strong"}
 
 # Create arc data for geom_path
@@ -121,6 +121,30 @@
 # Label data (positioned below nodes)
 label_df = pd.DataFrame({"x": x_positions, "y": [y_baseline - 0.045] * n_nodes, "name": nodes})
 
+# Legend data: small line segments showing weight encoding
+legend_x = 0.88
+legend_y_start = 0.78
+legend_spacing = 0.06
+legend_line_len = 0.07
+legend_lines = pd.DataFrame(
+    {
+        "x": [legend_x] * 3,
+        "xend": [legend_x + legend_line_len] * 3,
+        "y": [legend_y_start - i * legend_spacing for i in range(3)],
+        "yend": [legend_y_start - i * legend_spacing for i in range(3)],
+        "color": [weight_colors[3], weight_colors[2], weight_colors[1]],
+        "size": [1.0 + 3 * 1.2, 1.0 + 2 * 1.2, 1.0 + 1 * 1.2],
+        "alpha": [weight_alphas[3], weight_alphas[2], weight_alphas[1]],
+    }
+)
+legend_text_df = pd.DataFrame(
+    {
+        "x": [legend_x + legend_line_len + 0.015] * 3,
+        "y": [legend_y_start - i * legend_spacing for i in range(3)],
+        "label": ["Strong (3)", "Moderate (2)", "Weak (1)"],
+    }
+)
+
 # Plot
 plot = (
     ggplot()
@@ -148,12 +172,19 @@
     + scale_size_identity()
     # Node labels
     + geom_text(
-        data=label_df, mapping=aes(x="x", y="y", label="name"), size=16, color="#1A3A5C", fontface="bold", vjust=1
+        data=label_df, mapping=aes(x="x", y="y", label="name"), size=20, color="#1A3A5C", fontface="bold", vjust=1
+    )
+    # Weight legend
+    + geom_segment(
+        data=legend_lines,
+        mapping=aes(x="x", y="y", xend="xend", yend="yend", color="color", size="size", alpha="alpha"),
+        tooltips="none",
     )
+    + geom_text(data=legend_text_df, mapping=aes(x="x", y="y", label="label"), size=14, color="#1A3A5C", hjust=0)
     # Styling
     + xlim(-0.06, 1.06)
-    + ylim(-0.15, 0.85)
-    + labs(title="Character Interactions \u00b7 arc-basic \u00b7 letsplot \u00b7 pyplots.ai")
+    + ylim(-0.08, 0.85)
+    + labs(title="arc-basic \u00b7 letsplot \u00b7 pyplots.ai")
     + theme(
         axis_title=element_blank(),
         axis_text=element_blank(),

From 16d4e2d30a3e98482a3a77ce6338d8fd5de005e3 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]" <github-actions[bot]@users.noreply.github.com>
Date: Mon, 23 Feb 2026 21:45:51 +0000
Subject: [PATCH 4/8] chore(letsplot): update quality score 88 and review
 feedback for arc-basic

---
 plots/arc-basic/implementations/letsplot.py |   4 +-
 plots/arc-basic/metadata/letsplot.yaml      | 140 ++++++++++----------
 2 files changed, 71 insertions(+), 73 deletions(-)

diff --git a/plots/arc-basic/implementations/letsplot.py b/plots/arc-basic/implementations/letsplot.py
index 470b6d3a15..0b1b05a944 100644
--- a/plots/arc-basic/implementations/letsplot.py
+++ b/plots/arc-basic/implementations/letsplot.py
@@ -1,7 +1,7 @@
-"""pyplots.ai
+""" pyplots.ai
 arc-basic: Basic Arc Diagram
 Library: letsplot 4.8.2 | Python 3.14.3
-Quality: 87/100 | Updated: 2026-02-23
+Quality: 88/100 | Updated: 2026-02-23
 """
 
 import numpy as np
diff --git a/plots/arc-basic/metadata/letsplot.yaml b/plots/arc-basic/metadata/letsplot.yaml
index 1de3fd31e2..1516914e52 100644
--- a/plots/arc-basic/metadata/letsplot.yaml
+++ b/plots/arc-basic/metadata/letsplot.yaml
@@ -1,7 +1,7 @@
 library: letsplot
 specification_id: arc-basic
 created: '2025-12-23T08:49:14Z'
-updated: '2026-02-23T21:34:49Z'
+updated: '2026-02-23T21:45:51Z'
 generated_by: claude-opus-4-6
 workflow_run: 20455965726
 issue: 0
@@ -10,11 +10,12 @@ library_version: 4.8.2
 preview_url: https://storage.googleapis.com/pyplots-images/plots/arc-basic/letsplot/plot.png
 preview_thumb: https://storage.googleapis.com/pyplots-images/plots/arc-basic/letsplot/plot_thumb.png
 preview_html: https://storage.googleapis.com/pyplots-images/plots/arc-basic/letsplot/plot.html
-quality_score: 87
+quality_score: 88
 impl_tags:
   dependencies: []
   techniques:
   - layer-composition
+  - custom-legend
   - hover-tooltips
   - html-export
   patterns:
@@ -27,38 +28,34 @@ impl_tags:
   - edge-highlighting
 review:
   strengths:
-  - Clean cohesive blue monochromatic palette with yellow node accents creating effective
-    visual contrast
-  - 'Correct visual hierarchy: node size by connection weight, arc thickness/color/height
-    by edge weight'
-  - Comprehensive data covering all arc diagram features (short/long-range, varied
-    weights, overlapping arcs)
-  - Interactive tooltips via layer_tooltips showing connection details and strength
-  - Well-structured deterministic code with clean minimal chrome (all spines/axes/grid
-    removed)
+  - Cohesive monochromatic blue palette with intentional yellow accent creates professional
+    appearance
+  - Visual hierarchy through node size, arc height, and weight encoding effectively
+    communicates connectivity patterns
+  - All spec requirements fully met with appropriate data context (character interactions)
+  - Clean code structure with deterministic data and proper lets-plot API usage
+  - Interactive tooltips on arcs and nodes leverage lets-plot distinctive capabilities
   weaknesses:
-  - Title format includes non-standard prefix before required spec-id format, no weight
-    legend
-  - Weight-1 arcs are faint (alpha=0.5 with light blue) reducing visibility
-  - Wasted vertical space below node labels (ylim extends too far)
-  - Node label font size (16pt) could be larger for optimal readability at full resolution
+  - Legend text at size=14 is slightly small relative to other text elements
+  - Bottom portion of canvas has excess whitespace below node labels
+  - Weak (weight-1) arcs could have slightly better contrast against white background
   image_description: 'The plot displays a basic arc diagram with 10 character nodes
     (Alice, Bob, Carol, David, Eve, Frank, Grace, Henry, Iris, Jack) arranged along
-    a horizontal baseline from left to right. Each node is rendered as a yellow circle
-    (#FFD43B) with a dark blue (#1A3A5C) outline, with sizes varying by total connection
-    weight — Alice and David are the largest. Arcs connect node pairs above the baseline
-    using a blue monochromatic palette: light blue (#93B8CC, alpha 0.5) for weight-1
-    connections, medium blue (#306998, alpha 0.65) for weight-2, and dark blue (#1A3A5C,
-    alpha 0.8) for weight-3. Arc height is proportional to the distance between connected
-    nodes — the Alice-Jack arc spans the full width and reaches the highest point.
-    Arc thickness also scales with weight. A subtle gray baseline connects all nodes.
-    Node labels appear in bold dark blue text below the baseline. The title "Character
-    Interactions · arc-basic · letsplot · pyplots.ai" is positioned in the upper left
-    in bold dark blue. The background is clean white with no axes, spines, or grid
-    lines.'
+    a horizontal baseline on a clean white background. Arcs curve above the baseline
+    connecting pairs of nodes, with arc height proportional to the distance between
+    connected nodes — the Alice-Jack arc spans the full width and is the tallest.
+    Arcs use a monochromatic blue color scheme with three levels: Strong connections
+    (weight 3) are thick dark navy (#1A3A5C), Moderate (weight 2) are medium blue
+    (#306998), and Weak (weight 1) are thin light blue (#7FAABB) with varying transparency.
+    Nodes are rendered as yellow-filled circles (#FFD43B) with dark blue outlines,
+    sized proportionally to total connection weight — Alice and David appear as the
+    largest hubs. Bold dark navy labels sit below each node. A manual legend in the
+    upper right shows the three weight categories with matching line samples. The
+    title "arc-basic · letsplot · pyplots.ai" appears in bold dark text at the top
+    left.'
   criteria_checklist:
     visual_quality:
-      score: 27
+      score: 26
       max: 30
       items:
       - id: VQ-01
@@ -66,68 +63,68 @@ review:
         score: 7
         max: 8
         passed: true
-        comment: Title explicitly set to 24pt, node labels to 16pt bold. All readable;
-          labels could be slightly larger (18-20pt).
+        comment: Title at size=24 bold, node labels at size=20 bold, all clearly readable.
+          Legend text at size=14 is slightly below recommended 16pt minimum.
       - id: VQ-02
         name: No Overlap
-        score: 6
+        score: 5
         max: 6
         passed: true
-        comment: No overlapping text or elements. Labels well-spaced below baseline,
-          arcs above.
+        comment: No actual overlapping text, but Carol and David labels are quite
+          close together. All labels remain readable.
       - id: VQ-03
         name: Element Visibility
         score: 5
         max: 6
         passed: true
-        comment: Most elements well-sized. Weight-1 arcs (alpha=0.5, light blue) are
-          somewhat faint. Smaller nodes appear small.
+        comment: Arcs well-differentiated by thickness and color. Weak arcs somewhat
+          faint at 0.6 alpha with lightest blue.
       - id: VQ-04
         name: Color Accessibility
         score: 4
         max: 4
         passed: true
-        comment: Blue monochromatic scheme with yellow accents. Fully colorblind-safe.
+        comment: Monochromatic blue scheme is inherently colorblind-safe. Yellow accent
+          nodes provide strong contrast.
       - id: VQ-05
         name: Layout & Canvas
         score: 3
         max: 4
         passed: true
-        comment: Good horizontal utilization. Some wasted vertical space below node
-          labels.
+        comment: Good horizontal usage. Some wasted vertical space below the labels.
       - id: VQ-06
         name: Axis Labels & Title
         score: 2
         max: 2
         passed: true
-        comment: Descriptive title present. Axes appropriately hidden for arc diagram.
+        comment: Axes appropriately hidden. Title follows required format.
     design_excellence:
-      score: 14
+      score: 15
       max: 20
       items:
       - id: DE-01
         name: Aesthetic Sophistication
-        score: 5
+        score: 6
         max: 8
         passed: true
-        comment: Custom cohesive blue palette with yellow node accents, intentional
-          color hierarchy by weight. Above defaults but not publication-level.
+        comment: Strong design with cohesive monochromatic blue palette and intentional
+          yellow accent. Clear typographic hierarchy. Above defaults but not publication-ready.
       - id: DE-02
         name: Visual Refinement
         score: 5
         max: 6
         passed: true
-        comment: All spines, axes, and grid removed. Clean white background. Subtle
-          gray baseline. Well-polished minimal chrome.
+        comment: All chrome removed, clean white background, subtle baseline, well-crafted
+          manual legend. Minor excess whitespace at bottom.
       - id: DE-03
         name: Data Storytelling
         score: 4
         max: 6
         passed: true
-        comment: Visual hierarchy through node size, arc thickness/color, and arc
-          height. Alice and David naturally stand out.
+        comment: Visual hierarchy through node size, arc height, and weight encoding.
+          Alice and David emerge as hubs. Long-range vs short-range clearly visible.
     spec_compliance:
-      score: 14
+      score: 15
       max: 15
       items:
       - id: SC-01
@@ -136,28 +133,28 @@ review:
         max: 5
         passed: true
         comment: Correct arc diagram with nodes on horizontal line and curved arcs
-          above, height proportional to node distance.
+          above.
       - id: SC-02
         name: Required Features
         score: 4
         max: 4
         passed: true
-        comment: 'All spec features present: arcs, weight-based thickness/color, semi-transparency,
-          readable labels, proportional arc height.'
+        comment: 'All spec requirements present: ordered nodes, curved arcs, weight-based
+          styling, semi-transparency, readable labels, color coding.'
       - id: SC-03
         name: Data Mapping
         score: 3
         max: 3
         passed: true
-        comment: 10 nodes correctly positioned, 15 edges correctly mapped with proper
-          weight encoding.
+        comment: Nodes correctly positioned, arcs connect specified pairs, heights
+          proportional to distance.
       - id: SC-04
         name: Title & Legend
-        score: 2
+        score: 3
         max: 3
-        passed: false
-        comment: Title adds non-standard prefix before required format. No weight
-          legend.
+        passed: true
+        comment: Title follows required format. Manual legend accurately represents
+          weight categories.
     data_quality:
       score: 15
       max: 15
@@ -167,8 +164,8 @@ review:
         score: 6
         max: 6
         passed: true
-        comment: Shows short/long-range connections, three weight levels, overlapping
-          arcs, varied node connectivity.
+        comment: Shows short-range, long-range, varying weights, multiple hubs, diverse
+          connectivity patterns.
       - id: DQ-02
         name: Realistic Context
         score: 5
@@ -181,8 +178,7 @@ review:
         score: 4
         max: 4
         passed: true
-        comment: 10 nodes in recommended range, 15 edges at reasonable density, weights
-          1-3.
+        comment: 10 nodes, 15 edges, weights 1-3 — good density and clear differentiation.
     code_quality:
       score: 10
       max: 10
@@ -192,31 +188,32 @@ review:
         score: 3
         max: 3
         passed: true
-        comment: 'Flat script: imports, data, plot, save. No functions or classes.'
+        comment: Clean Imports → Data → Plot → Save structure with no functions or
+          classes.
       - id: CQ-02
         name: Reproducibility
         score: 2
         max: 2
         passed: true
-        comment: All data is deterministic (hard-coded nodes, edges, weights).
+        comment: All data is deterministic, hardcoded nodes and edges.
       - id: CQ-03
         name: Clean Imports
         score: 2
         max: 2
         passed: true
-        comment: All imports are used; no unused imports.
+        comment: All imports are used.
       - id: CQ-04
         name: Code Elegance
         score: 2
         max: 2
         passed: true
-        comment: Well-structured, readable code with appropriate complexity.
+        comment: Appropriate complexity for custom visualization. No fake functionality.
       - id: CQ-05
         name: Output & API
         score: 1
         max: 1
         passed: true
-        comment: Saves as plot.png with scale=3. Current lets_plot API.
+        comment: Saves as plot.png with ggsave(scale=3). Uses current lets-plot API.
     library_mastery:
       score: 7
       max: 10
@@ -226,13 +223,14 @@ review:
         score: 4
         max: 5
         passed: true
-        comment: Good grammar-of-graphics usage with layered geoms, aes mappings,
-          scale_*_identity(), theme customization.
+        comment: Proper ggplot grammar with layered geoms, aes mappings, scale_*_identity(),
+          and theme system. Manual arc calculation is appropriate since lets-plot
+          lacks native arc geom.
       - id: LM-02
         name: Distinctive Features
         score: 3
         max: 5
         passed: true
-        comment: Uses layer_tooltips() for hover information and HTML export via ggsave
-          — distinctive letsplot features.
+        comment: Uses layer_tooltips() for interactive hover on arcs and nodes. Exports
+          both PNG and HTML.
   verdict: REJECTED

From 821fed8d367f552680886447d3df1bfc8e66c141 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]" <github-actions[bot]@users.noreply.github.com>
Date: Mon, 23 Feb 2026 21:51:18 +0000
Subject: [PATCH 5/8] fix(letsplot): address review feedback for arc-basic

Attempt 2/3 - fixes based on AI review
---
 plots/arc-basic/implementations/letsplot.py | 25 ++++++++++++++-------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/plots/arc-basic/implementations/letsplot.py b/plots/arc-basic/implementations/letsplot.py
index 0b1b05a944..9e9c96a14c 100644
--- a/plots/arc-basic/implementations/letsplot.py
+++ b/plots/arc-basic/implementations/letsplot.py
@@ -1,4 +1,4 @@
-""" pyplots.ai
+"""pyplots.ai
 arc-basic: Basic Arc Diagram
 Library: letsplot 4.8.2 | Python 3.14.3
 Quality: 88/100 | Updated: 2026-02-23
@@ -66,8 +66,8 @@
     connections[t] += w
 
 # Arc color intensity by weight
-weight_colors = {1: "#7FAABB", 2: "#306998", 3: "#1A3A5C"}
-weight_alphas = {1: 0.6, 2: 0.7, 3: 0.85}
+weight_colors = {1: "#6A9BB5", 2: "#306998", 3: "#1A3A5C"}
+weight_alphas = {1: 0.7, 2: 0.75, 3: 0.9}
 weight_labels = {1: "Weak", 2: "Moderate", 3: "Strong"}
 
 # Create arc data for geom_path
@@ -122,8 +122,8 @@
 label_df = pd.DataFrame({"x": x_positions, "y": [y_baseline - 0.045] * n_nodes, "name": nodes})
 
 # Legend data: small line segments showing weight encoding
-legend_x = 0.88
-legend_y_start = 0.78
+legend_x = 0.82
+legend_y_start = 0.76
 legend_spacing = 0.06
 legend_line_len = 0.07
 legend_lines = pd.DataFrame(
@@ -144,6 +144,7 @@
         "label": ["Strong (3)", "Moderate (2)", "Weak (1)"],
     }
 )
+legend_title_df = pd.DataFrame({"x": [legend_x], "y": [legend_y_start + 0.05], "label": ["Connection Strength"]})
 
 # Plot
 plot = (
@@ -180,10 +181,18 @@
         mapping=aes(x="x", y="y", xend="xend", yend="yend", color="color", size="size", alpha="alpha"),
         tooltips="none",
     )
-    + geom_text(data=legend_text_df, mapping=aes(x="x", y="y", label="label"), size=14, color="#1A3A5C", hjust=0)
+    + geom_text(data=legend_text_df, mapping=aes(x="x", y="y", label="label"), size=16, color="#1A3A5C", hjust=0)
+    + geom_text(
+        data=legend_title_df,
+        mapping=aes(x="x", y="y", label="label"),
+        size=16,
+        color="#1A3A5C",
+        fontface="bold",
+        hjust=0,
+    )
     # Styling
-    + xlim(-0.06, 1.06)
-    + ylim(-0.08, 0.85)
+    + xlim(-0.06, 1.12)
+    + ylim(-0.04, 0.85)
     + labs(title="arc-basic \u00b7 letsplot \u00b7 pyplots.ai")
     + theme(
         axis_title=element_blank(),

From 32ecc5da7b6e94b1d3b6e731b9c75192549470a4 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]" <github-actions[bot]@users.noreply.github.com>
Date: Mon, 23 Feb 2026 21:57:26 +0000
Subject: [PATCH 6/8] chore(letsplot): update quality score 89 and review
 feedback for arc-basic

---
 plots/arc-basic/implementations/letsplot.py |   4 +-
 plots/arc-basic/metadata/letsplot.yaml      | 137 ++++++++++----------
 2 files changed, 73 insertions(+), 68 deletions(-)

diff --git a/plots/arc-basic/implementations/letsplot.py b/plots/arc-basic/implementations/letsplot.py
index 9e9c96a14c..98b956a87b 100644
--- a/plots/arc-basic/implementations/letsplot.py
+++ b/plots/arc-basic/implementations/letsplot.py
@@ -1,7 +1,7 @@
-"""pyplots.ai
+""" pyplots.ai
 arc-basic: Basic Arc Diagram
 Library: letsplot 4.8.2 | Python 3.14.3
-Quality: 88/100 | Updated: 2026-02-23
+Quality: 89/100 | Updated: 2026-02-23
 """
 
 import numpy as np
diff --git a/plots/arc-basic/metadata/letsplot.yaml b/plots/arc-basic/metadata/letsplot.yaml
index 1516914e52..44e70725a5 100644
--- a/plots/arc-basic/metadata/letsplot.yaml
+++ b/plots/arc-basic/metadata/letsplot.yaml
@@ -1,7 +1,7 @@
 library: letsplot
 specification_id: arc-basic
 created: '2025-12-23T08:49:14Z'
-updated: '2026-02-23T21:45:51Z'
+updated: '2026-02-23T21:57:26Z'
 generated_by: claude-opus-4-6
 workflow_run: 20455965726
 issue: 0
@@ -10,7 +10,7 @@ library_version: 4.8.2
 preview_url: https://storage.googleapis.com/pyplots-images/plots/arc-basic/letsplot/plot.png
 preview_thumb: https://storage.googleapis.com/pyplots-images/plots/arc-basic/letsplot/plot_thumb.png
 preview_html: https://storage.googleapis.com/pyplots-images/plots/arc-basic/letsplot/plot.html
-quality_score: 88
+quality_score: 89
 impl_tags:
   dependencies: []
   techniques:
@@ -28,76 +28,80 @@ impl_tags:
   - edge-highlighting
 review:
   strengths:
-  - Cohesive monochromatic blue palette with intentional yellow accent creates professional
-    appearance
-  - Visual hierarchy through node size, arc height, and weight encoding effectively
-    communicates connectivity patterns
-  - All spec requirements fully met with appropriate data context (character interactions)
-  - Clean code structure with deterministic data and proper lets-plot API usage
-  - Interactive tooltips on arcs and nodes leverage lets-plot distinctive capabilities
+  - Professional blue monochromatic palette with yellow node accents creates a distinctive,
+    polished look
+  - All spec requirements fully implemented including proportional arc height, weight
+    encoding, and semi-transparency
+  - Interactive tooltips leveraging lets-plot distinctive layer_tooltips feature
+  - Clean, minimal design with no visual clutter (all axes/grid/spines removed)
+  - 'Good data storytelling through visual hierarchy: node sizing reveals hub characters,
+    arc height shows connection range'
   weaknesses:
-  - Legend text at size=14 is slightly small relative to other text elements
-  - Bottom portion of canvas has excess whitespace below node labels
-  - Weak (weight-1) arcs could have slightly better contrast against white background
+  - Node labels Carol/David and Grace/Henry are very close together, reducing readability
+  - Some low-connectivity nodes (Eve, Grace) are relatively small
+  - Manual legend construction is verbose
+  - Some vertical canvas space underutilized below the node labels
   image_description: 'The plot displays a basic arc diagram with 10 character nodes
     (Alice, Bob, Carol, David, Eve, Frank, Grace, Henry, Iris, Jack) arranged along
-    a horizontal baseline on a clean white background. Arcs curve above the baseline
-    connecting pairs of nodes, with arc height proportional to the distance between
-    connected nodes — the Alice-Jack arc spans the full width and is the tallest.
-    Arcs use a monochromatic blue color scheme with three levels: Strong connections
-    (weight 3) are thick dark navy (#1A3A5C), Moderate (weight 2) are medium blue
-    (#306998), and Weak (weight 1) are thin light blue (#7FAABB) with varying transparency.
-    Nodes are rendered as yellow-filled circles (#FFD43B) with dark blue outlines,
-    sized proportionally to total connection weight — Alice and David appear as the
-    largest hubs. Bold dark navy labels sit below each node. A manual legend in the
-    upper right shows the three weight categories with matching line samples. The
-    title "arc-basic · letsplot · pyplots.ai" appears in bold dark text at the top
-    left.'
+    a horizontal baseline. Curved arcs connect pairs of nodes above the baseline,
+    with arc height proportional to the distance between connected nodes — the Alice-Jack
+    arc spanning the full width is the tallest. Arcs are rendered in a blue monochromatic
+    palette: dark navy (#1A3A5C) for strong (weight 3) connections, medium blue (#306998)
+    for moderate (weight 2), and light steel blue (#6A9BB5) for weak (weight 1). Arc
+    thickness also increases with weight. Nodes are yellow-filled circles (#FFD43B)
+    with dark blue outlines, sized proportionally to total connection weight — Alice,
+    Bob, Carol, and David appear largest. Bold dark blue node labels sit below the
+    baseline. A custom legend in the upper-right labeled "Connection Strength" shows
+    three line samples for Strong (3), Moderate (2), and Weak (1). The title "arc-basic
+    · letsplot · pyplots.ai" appears top-left in bold dark blue. The background is
+    clean white with no axes, grid, or spines.'
   criteria_checklist:
     visual_quality:
-      score: 26
+      score: 27
       max: 30
       items:
       - id: VQ-01
         name: Text Legibility
-        score: 7
+        score: 8
         max: 8
         passed: true
-        comment: Title at size=24 bold, node labels at size=20 bold, all clearly readable.
-          Legend text at size=14 is slightly below recommended 16pt minimum.
+        comment: 'All font sizes explicitly set: title=24, labels=20, legend=16. All
+          text clearly readable.'
       - id: VQ-02
         name: No Overlap
         score: 5
         max: 6
         passed: true
-        comment: No actual overlapping text, but Carol and David labels are quite
-          close together. All labels remain readable.
+        comment: Carol/David and Grace/Henry labels very close together, nearly touching
+          but not overlapping.
       - id: VQ-03
         name: Element Visibility
         score: 5
         max: 6
         passed: true
-        comment: Arcs well-differentiated by thickness and color. Weak arcs somewhat
-          faint at 0.6 alpha with lightest blue.
+        comment: Arcs well differentiated. Low-connectivity nodes (Eve, Grace) are
+          noticeably small.
       - id: VQ-04
         name: Color Accessibility
         score: 4
         max: 4
         passed: true
-        comment: Monochromatic blue scheme is inherently colorblind-safe. Yellow accent
-          nodes provide strong contrast.
+        comment: Blue monochromatic palette with yellow accents is fully colorblind-safe.
+          Redundant encoding via thickness and color.
       - id: VQ-05
         name: Layout & Canvas
         score: 3
         max: 4
         passed: true
-        comment: Good horizontal usage. Some wasted vertical space below the labels.
+        comment: Good horizontal spread. Some underutilized vertical space below labels
+          and in upper-left quadrant.
       - id: VQ-06
         name: Axis Labels & Title
         score: 2
         max: 2
         passed: true
-        comment: Axes appropriately hidden. Title follows required format.
+        comment: Axes appropriately hidden for arc diagram. Title in correct format.
+          Node labels serve as identifiers.
     design_excellence:
       score: 15
       max: 20
@@ -107,22 +111,22 @@ review:
         score: 6
         max: 8
         passed: true
-        comment: Strong design with cohesive monochromatic blue palette and intentional
-          yellow accent. Clear typographic hierarchy. Above defaults but not publication-ready.
+        comment: 'Strong design: cohesive blue monochromatic palette with yellow accent
+          for nodes. Clearly above library defaults.'
       - id: DE-02
         name: Visual Refinement
         score: 5
         max: 6
         passed: true
-        comment: All chrome removed, clean white background, subtle baseline, well-crafted
-          manual legend. Minor excess whitespace at bottom.
+        comment: 'Very clean: all axes/grid/spines removed, subtle gray baseline,
+          white background. Custom-styled legend.'
       - id: DE-03
         name: Data Storytelling
         score: 4
         max: 6
         passed: true
-        comment: Visual hierarchy through node size, arc height, and weight encoding.
-          Alice and David emerge as hubs. Long-range vs short-range clearly visible.
+        comment: 'Good visual hierarchy: node sizing reveals hub characters, arc height
+          shows connection range, thickness/color guides weight interpretation.'
     spec_compliance:
       score: 15
       max: 15
@@ -132,29 +136,29 @@ review:
         score: 5
         max: 5
         passed: true
-        comment: Correct arc diagram with nodes on horizontal line and curved arcs
-          above.
+        comment: 'Correct arc diagram: nodes along horizontal line with curved arcs
+          above.'
       - id: SC-02
         name: Required Features
         score: 4
         max: 4
         passed: true
-        comment: 'All spec requirements present: ordered nodes, curved arcs, weight-based
-          styling, semi-transparency, readable labels, color coding.'
+        comment: 'All spec features present: proportional arc height, semi-transparency,
+          readable labels, color-coded edges, thickness encoding.'
       - id: SC-03
         name: Data Mapping
         score: 3
         max: 3
         passed: true
-        comment: Nodes correctly positioned, arcs connect specified pairs, heights
-          proportional to distance.
+        comment: Nodes correctly positioned, arcs connect correct pairs, height/thickness/color
+          correctly mapped.
       - id: SC-04
         name: Title & Legend
         score: 3
         max: 3
         passed: true
-        comment: Title follows required format. Manual legend accurately represents
-          weight categories.
+        comment: Title in correct format. Custom legend clearly shows connection strength
+          encoding.
     data_quality:
       score: 15
       max: 15
@@ -164,21 +168,21 @@ review:
         score: 6
         max: 6
         passed: true
-        comment: Shows short-range, long-range, varying weights, multiple hubs, diverse
-          connectivity patterns.
+        comment: Shows short/medium/long-range connections, varied weights, varied
+          node connectivity, overlapping arcs.
       - id: DQ-02
         name: Realistic Context
         score: 5
         max: 5
         passed: true
-        comment: Character interactions in a story chapter — real, neutral, comprehensible
-          scenario.
+        comment: Character interactions in a story chapter — real, comprehensible,
+          neutral scenario matching spec application.
       - id: DQ-03
         name: Appropriate Scale
         score: 4
         max: 4
         passed: true
-        comment: 10 nodes, 15 edges, weights 1-3 — good density and clear differentiation.
+        comment: 10 nodes, 15 edges, weights 1-3 provide good density for readability.
     code_quality:
       score: 10
       max: 10
@@ -188,32 +192,34 @@ review:
         score: 3
         max: 3
         passed: true
-        comment: Clean Imports → Data → Plot → Save structure with no functions or
-          classes.
+        comment: 'Linear flow: imports → data → arc generation → node data → legend
+          data → plot → save. No functions or classes.'
       - id: CQ-02
         name: Reproducibility
         score: 2
         max: 2
         passed: true
-        comment: All data is deterministic, hardcoded nodes and edges.
+        comment: All data is deterministic (hardcoded nodes, edges, positions).
       - id: CQ-03
         name: Clean Imports
         score: 2
         max: 2
         passed: true
-        comment: All imports are used.
+        comment: All imports used. Specific imports from lets_plot.
       - id: CQ-04
         name: Code Elegance
         score: 2
         max: 2
         passed: true
-        comment: Appropriate complexity for custom visualization. No fake functionality.
+        comment: Clean parametric arc generation. Well-organized sections. Appropriate
+          complexity.
       - id: CQ-05
         name: Output & API
         score: 1
         max: 1
         passed: true
-        comment: Saves as plot.png with ggsave(scale=3). Uses current lets-plot API.
+        comment: Saves as plot.png via ggsave with scale=3. Uses current lets-plot
+          API.
     library_mastery:
       score: 7
       max: 10
@@ -223,14 +229,13 @@ review:
         score: 4
         max: 5
         passed: true
-        comment: Proper ggplot grammar with layered geoms, aes mappings, scale_*_identity(),
-          and theme system. Manual arc calculation is appropriate since lets-plot
-          lacks native arc geom.
+        comment: 'Good ggplot grammar: geom_path for arcs, geom_point for nodes, identity
+          scales, theme(). Manual legend is verbose but necessary.'
       - id: LM-02
         name: Distinctive Features
         score: 3
         max: 5
         passed: true
-        comment: Uses layer_tooltips() for interactive hover on arcs and nodes. Exports
-          both PNG and HTML.
+        comment: Uses layer_tooltips() with custom .line() formatting for interactive
+          hover — a distinctive lets-plot feature. HTML export alongside PNG.
   verdict: REJECTED

From 00a10d617af0976c3658e3daee1dc4322998f8a1 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]" <github-actions[bot]@users.noreply.github.com>
Date: Mon, 23 Feb 2026 22:03:49 +0000
Subject: [PATCH 7/8] fix(letsplot): address review feedback for arc-basic

Attempt 3/3 - fixes based on AI review
---
 plots/arc-basic/implementations/letsplot.py | 33 +++++++++++----------
 1 file changed, 18 insertions(+), 15 deletions(-)

diff --git a/plots/arc-basic/implementations/letsplot.py b/plots/arc-basic/implementations/letsplot.py
index 98b956a87b..fcac090d03 100644
--- a/plots/arc-basic/implementations/letsplot.py
+++ b/plots/arc-basic/implementations/letsplot.py
@@ -1,7 +1,6 @@
-""" pyplots.ai
+"""pyplots.ai
 arc-basic: Basic Arc Diagram
 Library: letsplot 4.8.2 | Python 3.14.3
-Quality: 89/100 | Updated: 2026-02-23
 """
 
 import numpy as np
@@ -55,9 +54,9 @@
     (8, 9, 2),  # Iris-Jack
 ]
 
-# Node positions along x-axis
-x_positions = np.linspace(0, 1, n_nodes)
-y_baseline = 0.08
+# Node positions along x-axis — wider spacing for label readability
+x_positions = np.linspace(0, 1.3, n_nodes)
+y_baseline = 0.06
 
 # Count connections per node for visual hierarchy
 connections = [0] * n_nodes
@@ -108,9 +107,9 @@
 
 arc_df = pd.DataFrame(arc_data)
 
-# Node data with size based on total connection weight
+# Node data with size based on total connection weight (higher floor for peripheral nodes)
 max_conn = max(connections)
-node_sizes = [6 + 10 * (c / max_conn) for c in connections]
+node_sizes = [9 + 7 * (c / max_conn) for c in connections]
 node_df = pd.DataFrame(
     {"x": x_positions, "y": [y_baseline] * n_nodes, "name": nodes, "node_size": node_sizes, "connections": connections}
 )
@@ -119,11 +118,11 @@
 baseline_df = pd.DataFrame({"x": [x_positions[0]], "xend": [x_positions[-1]], "y": [y_baseline], "yend": [y_baseline]})
 
 # Label data (positioned below nodes)
-label_df = pd.DataFrame({"x": x_positions, "y": [y_baseline - 0.045] * n_nodes, "name": nodes})
+label_df = pd.DataFrame({"x": x_positions, "y": [y_baseline - 0.04] * n_nodes, "name": nodes})
 
 # Legend data: small line segments showing weight encoding
-legend_x = 0.82
-legend_y_start = 0.76
+legend_x = 1.1
+legend_y_start = 0.72
 legend_spacing = 0.06
 legend_line_len = 0.07
 legend_lines = pd.DataFrame(
@@ -155,7 +154,7 @@
     + geom_path(
         data=arc_df,
         mapping=aes(x="x", y="y", group="edge_id", size="size", color="color", alpha="alpha"),
-        tooltips=layer_tooltips().line("@connection").line("Strength: @strength"),
+        tooltips=layer_tooltips().title("@connection").line("Strength|@strength"),
     )
     + scale_size_identity()
     + scale_color_identity()
@@ -168,7 +167,7 @@
         fill="#FFD43B",
         stroke=1.5,
         shape=21,
-        tooltips=layer_tooltips().line("@name").line("Connections: @connections"),
+        tooltips=layer_tooltips().title("@name").line("Total weight|@connections"),
     )
     + scale_size_identity()
     # Node labels
@@ -191,9 +190,12 @@
         hjust=0,
     )
     # Styling
-    + xlim(-0.06, 1.12)
-    + ylim(-0.04, 0.85)
-    + labs(title="arc-basic \u00b7 letsplot \u00b7 pyplots.ai")
+    + xlim(-0.05, 1.48)
+    + ylim(-0.01, 0.82)
+    + labs(
+        title="arc-basic \u00b7 letsplot \u00b7 pyplots.ai",
+        subtitle="Character interactions in a story chapter \u2014 node size reflects connection strength",
+    )
     + theme(
         axis_title=element_blank(),
         axis_text=element_blank(),
@@ -203,6 +205,7 @@
         panel_background=element_rect(fill="white", color="white"),
         plot_background=element_rect(fill="white", color="white"),
         plot_title=element_text(size=24, face="bold", color="#1A3A5C"),
+        plot_subtitle=element_text(size=16, color="#4A6B82"),
         legend_position="none",
     )
     + ggsize(1600, 900)

From 67eecf903930b68dd0a7bb718a34bec7dca07787 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]" <github-actions[bot]@users.noreply.github.com>
Date: Mon, 23 Feb 2026 22:11:02 +0000
Subject: [PATCH 8/8] chore(letsplot): update quality score 89 and review
 feedback for arc-basic

---
 plots/arc-basic/implementations/letsplot.py |   3 +-
 plots/arc-basic/metadata/letsplot.yaml      | 131 ++++++++++----------
 2 files changed, 65 insertions(+), 69 deletions(-)

diff --git a/plots/arc-basic/implementations/letsplot.py b/plots/arc-basic/implementations/letsplot.py
index fcac090d03..2ec4bd977e 100644
--- a/plots/arc-basic/implementations/letsplot.py
+++ b/plots/arc-basic/implementations/letsplot.py
@@ -1,6 +1,7 @@
-"""pyplots.ai
+""" pyplots.ai
 arc-basic: Basic Arc Diagram
 Library: letsplot 4.8.2 | Python 3.14.3
+Quality: 89/100 | Updated: 2026-02-23
 """
 
 import numpy as np
diff --git a/plots/arc-basic/metadata/letsplot.yaml b/plots/arc-basic/metadata/letsplot.yaml
index 44e70725a5..9fd0be51cc 100644
--- a/plots/arc-basic/metadata/letsplot.yaml
+++ b/plots/arc-basic/metadata/letsplot.yaml
@@ -1,7 +1,7 @@
 library: letsplot
 specification_id: arc-basic
 created: '2025-12-23T08:49:14Z'
-updated: '2026-02-23T21:57:26Z'
+updated: '2026-02-23T22:11:01Z'
 generated_by: claude-opus-4-6
 workflow_run: 20455965726
 issue: 0
@@ -28,33 +28,33 @@ impl_tags:
   - edge-highlighting
 review:
   strengths:
-  - Professional blue monochromatic palette with yellow node accents creates a distinctive,
-    polished look
-  - All spec requirements fully implemented including proportional arc height, weight
-    encoding, and semi-transparency
-  - Interactive tooltips leveraging lets-plot distinctive layer_tooltips feature
-  - Clean, minimal design with no visual clutter (all axes/grid/spines removed)
-  - 'Good data storytelling through visual hierarchy: node sizing reveals hub characters,
-    arc height shows connection range'
+  - 'Excellent spec compliance with all required features: proportional arc heights,
+    semi-transparency, weight-based color/thickness encoding, and readable labels'
+  - Thoughtful custom blue palette with yellow node highlights creates a cohesive
+    professional color scheme
+  - Triple visual encoding (node size + arc thickness + arc color) enables effective
+    data storytelling
+  - Clean code with deterministic data and appropriate KISS structure
+  - Uses distinctive letsplot features (layer_tooltips, HTML export) for added interactivity
   weaknesses:
-  - Node labels Carol/David and Grace/Henry are very close together, reducing readability
-  - Some low-connectivity nodes (Eve, Grace) are relatively small
-  - Manual legend construction is verbose
-  - Some vertical canvas space underutilized below the node labels
+  - Subtitle font at 16pt appears slightly small relative to the overall design; could
+    be 18-20pt
+  - Upper-left canvas area is underutilized creating mild visual imbalance
+  - Weak (weight=1) arcs are somewhat thin/light reducing their visual prominence
+  - Library mastery could be pushed further with additional distinctive letsplot features
   image_description: 'The plot displays a basic arc diagram with 10 character nodes
     (Alice, Bob, Carol, David, Eve, Frank, Grace, Henry, Iris, Jack) arranged along
     a horizontal baseline. Curved arcs connect pairs of nodes above the baseline,
     with arc height proportional to the distance between connected nodes — the Alice-Jack
-    arc spanning the full width is the tallest. Arcs are rendered in a blue monochromatic
-    palette: dark navy (#1A3A5C) for strong (weight 3) connections, medium blue (#306998)
-    for moderate (weight 2), and light steel blue (#6A9BB5) for weak (weight 1). Arc
-    thickness also increases with weight. Nodes are yellow-filled circles (#FFD43B)
-    with dark blue outlines, sized proportionally to total connection weight — Alice,
-    Bob, Carol, and David appear largest. Bold dark blue node labels sit below the
-    baseline. A custom legend in the upper-right labeled "Connection Strength" shows
-    three line samples for Strong (3), Moderate (2), and Weak (1). The title "arc-basic
-    · letsplot · pyplots.ai" appears top-left in bold dark blue. The background is
-    clean white with no axes, grid, or spines.'
+    arc spans the full width and rises highest. Arcs vary in thickness and color intensity
+    by connection weight: dark navy/thick for "Strong (3)", medium blue for "Moderate
+    (2)", and lighter blue/thin for "Weak (1)". Nodes are yellow-filled circles with
+    dark blue outlines, sized proportionally to total connection weight (Alice and
+    David appear largest). A manually constructed legend titled "Connection Strength"
+    in the upper right shows three weight levels. The title reads "arc-basic · letsplot
+    · pyplots.ai" in bold dark blue, with a lighter subtitle "Character interactions
+    in a story chapter — node size reflects connection strength". White background,
+    no axes or grid.'
   criteria_checklist:
     visual_quality:
       score: 27
@@ -62,46 +62,44 @@ review:
       items:
       - id: VQ-01
         name: Text Legibility
-        score: 8
+        score: 7
         max: 8
         passed: true
-        comment: 'All font sizes explicitly set: title=24, labels=20, legend=16. All
-          text clearly readable.'
+        comment: All font sizes explicitly set (title=24, labels=20, legend=16). Subtitle
+          at 16pt readable but slightly small relative to design.
       - id: VQ-02
         name: No Overlap
-        score: 5
+        score: 6
         max: 6
         passed: true
-        comment: Carol/David and Grace/Henry labels very close together, nearly touching
-          but not overlapping.
+        comment: No overlapping text. Node labels well-spaced via linspace.
       - id: VQ-03
         name: Element Visibility
         score: 5
         max: 6
         passed: true
-        comment: Arcs well differentiated. Low-connectivity nodes (Eve, Grace) are
-          noticeably small.
+        comment: Nodes visible as yellow dots with dark outlines. Weak arcs somewhat
+          thin but discernible.
       - id: VQ-04
         name: Color Accessibility
         score: 4
         max: 4
         passed: true
-        comment: Blue monochromatic palette with yellow accents is fully colorblind-safe.
-          Redundant encoding via thickness and color.
+        comment: Monochromatic blue palette with yellow highlights. No colorblind
+          issues.
       - id: VQ-05
         name: Layout & Canvas
         score: 3
         max: 4
         passed: true
-        comment: Good horizontal spread. Some underutilized vertical space below labels
-          and in upper-left quadrant.
+        comment: Plot fills ~60% of canvas. Upper-left has some unused space.
       - id: VQ-06
         name: Axis Labels & Title
         score: 2
         max: 2
         passed: true
-        comment: Axes appropriately hidden for arc diagram. Title in correct format.
-          Node labels serve as identifiers.
+        comment: Axes appropriately hidden for network diagram. Title and subtitle
+          provide context.
     design_excellence:
       score: 15
       max: 20
@@ -111,22 +109,22 @@ review:
         score: 6
         max: 8
         passed: true
-        comment: 'Strong design: cohesive blue monochromatic palette with yellow accent
-          for nodes. Clearly above library defaults.'
+        comment: Custom blue palette with yellow node highlights. Bold title/subtitle
+          hierarchy. Clearly above defaults.
       - id: DE-02
         name: Visual Refinement
         score: 5
         max: 6
         passed: true
-        comment: 'Very clean: all axes/grid/spines removed, subtle gray baseline,
-          white background. Custom-styled legend.'
+        comment: All chrome removed. Subtle baseline. Manual legend. Generous whitespace.
+          Very clean.
       - id: DE-03
         name: Data Storytelling
         score: 4
         max: 6
         passed: true
-        comment: 'Good visual hierarchy: node sizing reveals hub characters, arc height
-          shows connection range, thickness/color guides weight interpretation.'
+        comment: 'Triple encoding: node size, arc thickness, arc color. Alice clearly
+          most connected. Long vs short range visible.'
     spec_compliance:
       score: 15
       max: 15
@@ -136,29 +134,29 @@ review:
         score: 5
         max: 5
         passed: true
-        comment: 'Correct arc diagram: nodes along horizontal line with curved arcs
-          above.'
+        comment: Correct arc diagram with nodes along horizontal line and curved arcs
+          above.
       - id: SC-02
         name: Required Features
         score: 4
         max: 4
         passed: true
-        comment: 'All spec features present: proportional arc height, semi-transparency,
-          readable labels, color-coded edges, thickness encoding.'
+        comment: 'All spec features present: proportional arc heights, semi-transparency,
+          color-coded edges, weight-based thickness.'
       - id: SC-03
         name: Data Mapping
         score: 3
         max: 3
         passed: true
-        comment: Nodes correctly positioned, arcs connect correct pairs, height/thickness/color
-          correctly mapped.
+        comment: Nodes correctly positioned. Arcs connect correct pairs with height
+          proportional to distance.
       - id: SC-04
         name: Title & Legend
         score: 3
         max: 3
         passed: true
-        comment: Title in correct format. Custom legend clearly shows connection strength
-          encoding.
+        comment: Title matches required format. Manual legend accurately shows weight
+          levels.
     data_quality:
       score: 15
       max: 15
@@ -168,21 +166,21 @@ review:
         score: 6
         max: 6
         passed: true
-        comment: Shows short/medium/long-range connections, varied weights, varied
-          node connectivity, overlapping arcs.
+        comment: Shows short/long range connections, all weight levels, varying node
+          sizes from hub to peripheral.
       - id: DQ-02
         name: Realistic Context
         score: 5
         max: 5
         passed: true
-        comment: Character interactions in a story chapter — real, comprehensible,
-          neutral scenario matching spec application.
+        comment: Character interactions in a story chapter. Neutral, real-world scenario.
       - id: DQ-03
         name: Appropriate Scale
         score: 4
         max: 4
         passed: true
-        comment: 10 nodes, 15 edges, weights 1-3 provide good density for readability.
+        comment: 10 nodes (within recommended range), 15 edges, weights 1-3. Sensible
+          for domain.
     code_quality:
       score: 10
       max: 10
@@ -192,34 +190,31 @@ review:
         score: 3
         max: 3
         passed: true
-        comment: 'Linear flow: imports → data → arc generation → node data → legend
-          data → plot → save. No functions or classes.'
+        comment: Imports → Data → Arc generation → Plot → Save. No functions or classes.
       - id: CQ-02
         name: Reproducibility
         score: 2
         max: 2
         passed: true
-        comment: All data is deterministic (hardcoded nodes, edges, positions).
+        comment: All data deterministic. No random generation.
       - id: CQ-03
         name: Clean Imports
         score: 2
         max: 2
         passed: true
-        comment: All imports used. Specific imports from lets_plot.
+        comment: All imports used. No unused imports.
       - id: CQ-04
         name: Code Elegance
         score: 2
         max: 2
         passed: true
-        comment: Clean parametric arc generation. Well-organized sections. Appropriate
-          complexity.
+        comment: Clean arc generation loop. Appropriate complexity.
       - id: CQ-05
         name: Output & API
         score: 1
         max: 1
         passed: true
-        comment: Saves as plot.png via ggsave with scale=3. Uses current lets-plot
-          API.
+        comment: Saves as plot.png via ggsave with scale=3. Current API.
     library_mastery:
       score: 7
       max: 10
@@ -229,13 +224,13 @@ review:
         score: 4
         max: 5
         passed: true
-        comment: 'Good ggplot grammar: geom_path for arcs, geom_point for nodes, identity
-          scales, theme(). Manual legend is verbose but necessary.'
+        comment: 'Good ggplot grammar: geom_path, geom_point, geom_text. Uses scale_*_identity()
+          for pre-computed aesthetics.'
       - id: LM-02
         name: Distinctive Features
         score: 3
         max: 5
         passed: true
-        comment: Uses layer_tooltips() with custom .line() formatting for interactive
-          hover — a distinctive lets-plot feature. HTML export alongside PNG.
+        comment: Uses layer_tooltips() for interactive hover and exports HTML. Distinctive
+          letsplot features.
   verdict: REJECTED