feat(pygal): implement waveform-audio

[github-actions]

Implementation: waveform-audio - python/pygal

Implements the python/pygal version of waveform-audio.

File: plots/waveform-audio/implementations/python/pygal.py

Parent Issue: #4563

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🤖 impl-generate workflow

[claude]

AI Review - Attempt 1/3

Image Description

Light render (plot-light.png): Warm off-white background (#FAF8F1) — correctly matches the light theme surface. Title "waveform-audio · python · pygal · anyplot.ai" clearly visible in dark ink at top center (~50-55% canvas width). Y-axis label "Amplitude" and X-axis label "Time (s)" both readable. Y-axis ticks (-1.000 to 1.000 with 3 decimal places) and X-axis ticks (0.00 to 0.14) are clear. Legend at bottom shows Waveform (green swatch), Decay envelope (purple swatch), Peak transient (red swatch). The main waveform is a green (#009E73) filled area with semi-transparent opacity showing a decaying oscillation — attack near x=0.01s, decaying rightward. Purple (#C475FD) dashed envelope lines trace the amplitude bounds. A red dot (#AE3030) marks the peak transient at the attack. Y-axis grid lines are subtle. All text is readable against the light background.

Dark render (plot-dark.png): Warm near-black background (#1A1A17) — correctly matches the dark theme. Title and all axis labels rendered in light-colored text (near #F0EFE8), clearly readable against the dark background. No dark-on-dark failures. Data colors are identical to the light render: green waveform (#009E73), purple envelope (#C475FD), red peak dot (#AE3030). The decaying waveform shape and all annotations appear in the same positions as the light render — only the background and chrome have flipped. Legibility verdict: PASS for both renders.

Score: 89/100

Category	Score	Max
Visual Quality	28	30
Design Excellence	12	20
Spec Compliance	15	15
Data Quality	15	15
Code Quality	10	10
Library Mastery	9	10
Total	89	100

Visual Quality (28/30)

• VQ-01: Text Legibility (7/8) — All font sizes explicitly set per library spec (title=66, label=56, major_label=44, legend=44). All text readable in both renders. Y-axis ticks with 3 decimal places slightly verbose but readable.
• VQ-02: No Overlap (6/6) — No text or element overlap in either render.
• VQ-03: Element Visibility (5/6) — Waveform and peak transient clearly visible. Zero reference dashed line (INK_MUTED, width=1.5) may be partially obscured beneath the waveform fill in the center.
• VQ-04: Color Accessibility (2/2) — Imprint palette is CVD-safe; green/purple/red distinguishable under deuteranopia.
• VQ-05: Layout & Canvas (4/4) — 3200×1800 landscape; canvas gate passed; good margins; no clipping; no AR-09.
• VQ-06: Axis Labels & Title (2/2) — "Time (s)" with unit; "Amplitude" descriptive; title matches required format exactly.
• VQ-07: Palette Compliance (2/2) — First series #009E73 ✓; envelope #C475FD (position 2) ✓; peak #AE3030 (semantic exception — correct for peak/transient anchor) ✓; zero line uses INK_MUTED theme-adaptive neutral ✓; backgrounds #FAF8F1/#1A1A17 correct; data colors identical across both renders ✓.

Design Excellence (12/20)

• DE-01: Aesthetic Sophistication (5/8) — Multi-layer design with intentional semantic color assignment. Cubic interpolation. Above the 4/8 default for configured library appearance but retains default pygal frame styling — not yet at 6/8 strong design level.
• DE-02: Visual Refinement (3/6) — Semi-transparent fill (opacity=0.65) ✓, Y-axis grid only ✓, dashed strokes for secondary elements ✓, show_dots=False for dense waveform ✓. One point above default. Margins and whitespace could be more generous.
• DE-03: Data Storytelling (4/6) — Clear visual hierarchy: waveform (primary green) > envelope (secondary dashed purple) > peak transient (semantic red dot). The red dot immediately draws the eye to the attack transient. Two points above default.

Spec Compliance (15/15)

• SC-01: Plot Type (5/5) — Correct audio waveform plot with filled area representation, symmetric around zero.
• SC-02: Required Features (4/4) — Filled area, semi-transparent opacity, zero reference line, time X-axis, amplitude Y-axis range (-1 to +1), decay envelope (upper + lower), peak transient marker, synthetic audio data.
• SC-03: Data Mapping (3/3) — Time on X in seconds, normalized amplitude on Y, all data visible.
• SC-04: Title & Legend (3/3) — Title matches required format exactly. Legend shows Waveform, Decay envelope, Peak transient.

Data Quality (15/15)

• DQ-01: Feature Coverage (6/6) — Shows waveform oscillation with attack/decay, envelope bounds, peak transient identification, and zero reference.
• DQ-02: Realistic Context (5/5) — A3 musical note (220 Hz) with harmonics and physically accurate exponential decay; neutral topic.
• DQ-03: Appropriate Scale (4/4) — 44100 Hz sample rate, 0.15s duration, normalized amplitude −1 to +1.

Code Quality (10/10)

• CQ-01: KISS Structure (3/3) — Flat script with necessary importlib workaround.
• CQ-02: Reproducibility (2/2) — np.random.seed(42) set.
• CQ-03: Clean Imports (2/2) — All imports used.
• CQ-04: Code Elegance (2/2) — Clean, no fake UI.
• CQ-05: Output & API (1/1) — Saves plot-{THEME}.png and plot-{THEME}.html correctly.

Library Mastery (9/10)

• LM-01: Idiomatic Usage (5/5) — Highly idiomatic: Style object, per-point dict format, per-series stroke_style, x_value_formatter, cubic interpolation, explicit_size, legend_at_bottom, js=[] for PNG mode.
• LM-02: Distinctive Features (4/5) — Per-point dict format {"value": (...), "label": "..."} is pygal-distinctive, enabling rich interactive tooltips in the HTML output. HTML alongside PNG makes full use of pygal's interactive SVG nature.

Score Caps Applied

• None

Strengths

• Correct Imprint palette with semantic intent: green waveform, purple envelope, semantic red peak transient — all applied correctly
• Highly idiomatic pygal usage: per-point dict format with rich labels, multiple stroke_style configurations, cubic interpolation, interactive HTML output
• Full spec compliance: filled area, semi-transparent fill, decay envelope (upper + lower dashed), peak transient marker, zero reference, synthetic A3 note data
• Both themes render correctly with no dark-on-dark failures; data colors identical across renders
• Realistic audio domain (220 Hz A3 note with harmonics and exponential decay); clean, reproducible code

Weaknesses

• DE-01: Chart retains default pygal frame styling. Increasing margins (margin_top/bottom/left/right) for more whitespace, and any visual refinement beyond configured defaults, would improve aesthetic sophistication.
• DE-02: Zero reference dashed line (INK_MUTED, width=1.5) is subtle and may be partially obscured within the waveform fill. Render it as the first series so pygal draws it beneath the fill, or increase stroke width to make it more prominent. Also consider more generous whitespace.
• VQ-03: Zero reference line visibility is marginal within the filled waveform area.

Issues Found

1. DE-01 BELOW THRESHOLD: Chart is well-configured but retains default pygal border frame
   • Fix: Increase all margins (e.g. margin_top=80, margin_bottom=100, margin_left=100) for more generous whitespace; explore style tweaks to reduce the boxy appearance. A custom font family would also add distinctiveness.
2. DE-02 BELOW THRESHOLD: Zero reference line may be obscured by waveform fill
   • Fix: Add the zero reference series as the first call (before the waveform) so pygal renders it on the bottom layer, visible through the semi-transparent waveform fill. Alternatively, increase its stroke width to 2.5 or 3.

AI Feedback for Next Attempt

The implementation is strong (89/100) — just 1 point below the 90 threshold for Attempt 1 approval. Focus exclusively on Design Excellence: (1) Increase margins for more breathing room (margin_top=80, margin_bottom=100, margin_left=100, margin_right=60); (2) Ensure the zero reference dashed line is added before the waveform series so it appears beneath the fill; (3) Consider a very subtle refinement to the chart frame — any improvement beyond the default pygal border appearance. The palette, spec compliance, data quality, and code quality are all perfect — this needs only small design polish to approve.

Verdict: REJECTED

[github-actions]

🔧 Repair Attempt 1/4

Applied fixes based on AI review feedback.

Status: Repair completed, re-triggering review...

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🤖 impl-repair

[claude]

AI Review - Attempt 2/3

Image Description

Light render (plot-light.png): The plot is rendered on a warm off-white #FAF8F1 background. The title "waveform-audio · python · pygal · anyplot.ai" appears in dark ink at the top, well-sized and clearly readable. The waveform itself is a semi-transparent green fill (#009E73, Imprint position 1) showing the oscillatory A3 note signal (220 Hz + harmonics) with an exponential decay envelope. Two dashed purple lines (#C475FD, Imprint position 2) trace the upper and lower decay envelope bounds, forming a characteristic decaying envelope shape widest at the attack (~0.014s) and narrowing rightward. A red dot (#AE3030) marks the peak transient at the attack. A subtle dashed gray zero-reference line is visible at y=0 through the waveform fill. X-axis shows "Time (s)" from 0.00 to 0.14 with clear tick labels; Y-axis shows "Amplitude" from -1.0 to 1.0. Legend at bottom lists "Waveform", "Decay envelope", "Peak transient" — all legible. All text is clearly readable against the light background. No legibility failures.

Dark render (plot-dark.png): The same plot is rendered on a warm near-black #1A1A17 background. Title, axis labels, and tick labels flip to light text (#F0EFE8 range) and are clearly readable against the dark surface. Data colors are identical to the light render: the green waveform fill, purple dashed envelope bounds, and red peak marker all retain their Imprint palette colors. The zero reference dashed line is visible as a muted gray through the center. The waveform oscillation pattern and decay envelope are clearly distinguishable from the dark background. No "dark-on-dark" failures observed — tick labels, axis labels, legend text, and title are all legible. Brand green #009E73 reads clearly on the dark surface. Both chrome elements (background, text) have flipped correctly while data colors remain constant.

Both paragraphs are required. A review that only describes one render is invalid.

Score: 87/100

Category	Score	Max
Visual Quality	28	30
Design Excellence	12	20
Spec Compliance	15	15
Data Quality	15	15
Code Quality	10	10
Library Mastery	7	10
Total	87	100

Visual Quality (28/30)

• VQ-01: Text Legibility (7/8) — Font sizes correctly set per pygal guide (title=66, label=56, major_label=44, legend=44). Both renders fully legible. Minor: Y-axis label "Amplitude" at fontsize 56 is slightly generous for a short label but not disproportional.
• VQ-02: No Overlap (6/6) — Clean layout throughout. Legend at bottom. No collisions between text, data, or annotations.
• VQ-03: Element Visibility (5/6) — Waveform fill, envelope dashed lines, and peak transient marker are all clearly visible. Zero reference line (dashed INK_MUTED) is present but somewhat subtle behind the dense waveform fill; acceptable for this plot type but slightly harder to isolate.
• VQ-04: Color Accessibility (2/2) — Imprint palette used correctly; green/purple/red combination is CVD-safe.
• VQ-05: Layout & Canvas (4/4) — Canvas is 3200×1800 ✓. Canvas gate passed. Generous margins, nothing cut off or overflowing.
• VQ-06: Axis Labels & Title (2/2) — Title matches required format exactly. X-axis "Time (s)" and Y-axis "Amplitude" are descriptive with appropriate unit context.
• VQ-07: Palette Compliance (2/2) — First series #009E73 ✓. Imprint positions 2 and 5 used for envelope and peak. Backgrounds #FAF8F1 (light) / #1A1A17 (dark) ✓. Both renders theme-correct.

Design Excellence (12/20)

• DE-01: Aesthetic Sophistication (5/8) — Above generic defaults. Intentional color hierarchy: green primary waveform, purple envelope boundary, semantic red peak anchor. Semi-transparent fill at 0.65 opacity. Cubic interpolation produces smooth waveform lines. Dashed envelope with linecap: round shows design attention.
• DE-02: Visual Refinement (3/6) — Y-guides only (no X-guides) is the right choice for a waveform plot. Dashed stroke with custom dasharray, round linecaps, and opacity on the fill are refinements above defaults. Chart has pygal's standard box frame (full spine removal not available in pygal the same way as matplotlib — not a deduction).
• DE-03: Data Storytelling (4/6) — Clear focal point: red peak transient marker draws the eye to the attack. Decay envelope provides context for the signal's dynamic range. Color hierarchy naturally guides from primary data (green) → boundary context (purple) → extreme event (red). Zero baseline anchors the signal.

Spec Compliance (15/15)

• SC-01: Plot Type (5/5) — Correct filled area waveform, symmetric above and below zero, in time domain.
• SC-02: Required Features (4/4) — Filled area ✓, zero-line ✓, semi-transparent fill ✓, envelope representation ✓, x-axis in seconds ✓, y-axis -1.0 to 1.0 ✓.
• SC-03: Data Mapping (3/3) — X: time in seconds (0.0 to 0.15), Y: normalized amplitude (-1.0 to 1.0). Signal generated at 44100 Hz for 0.15s = ~6600 samples (within 5000–50000 spec range).
• SC-04: Title & Legend (3/3) — Title is exactly waveform-audio · python · pygal · anyplot.ai ✓. Legend labels "Waveform", "Decay envelope", "Peak transient" are clear and descriptive.

Data Quality (15/15)

• DQ-01: Feature Coverage (6/6) — Covers all key waveform features: oscillatory shape, attack-decay dynamics, harmonics (220 Hz + 2nd, 3rd, 5th), dynamic range, peak transient, envelope bounds, zero baseline.
• DQ-02: Realistic Context (5/5) — A3 musical note (220 Hz) with physical harmonics and exponential decay — realistically models a plucked string or struck percussion sound. Standard 44100 Hz sample rate.
• DQ-03: Appropriate Scale (4/4) — Y-axis spans the full -1.0 to +1.0 normalized range. Amplitude peaks at 0.92 — realistic headroom. Duration of 0.15s appropriately shows the attack-sustain-decay pattern.

Code Quality (10/10)

• CQ-01: KISS Structure (3/3) — No functions or classes. Flat, linear structure throughout.
• CQ-02: Reproducibility (2/2) — np.random.seed(42) set; signal is fully deterministic.
• CQ-03: Clean Imports (2/2) — All imported modules (importlib.util, os, sys, numpy, pygal, pygal.style) are used.
• CQ-04: Code Elegance (2/2) — Per-point dict format with value/label tuples is the correct pygal pattern for rich tooltips. The import shadowing workaround is necessary and clearly commented.
• CQ-05: Output & API (1/1) — Saves plot-{THEME}.png and plot-{THEME}.html ✓. Uses current pygal 3.1.0 API.

Library Mastery (7/10)

• LM-01: Idiomatic Usage (4/5) — Per-point dict format with {"value": (x, y), "label": ...} is the idiomatic pygal XY pattern. stroke_style dict, fill=True, interpolate="cubic", legend_at_bottom=True, explicit_size=True are all correct pygal idioms.
• LM-02: Distinctive Features (3/5) — Rich per-point interactive tooltips across 1200 data points (distinctive pygal feature unavailable in static libraries). Interactive HTML output with pygal's JS rendering. Custom stroke style with dasharray/linecap for dashed envelope lines.

Score Caps Applied

• None

Strengths

• Perfect spec compliance: fills all required features (filled waveform, zero-line, semi-transparent fill, envelope, time axis, normalized amplitude)
• Excellent data quality: physically realistic A3 musical note with harmonics and exponential decay, appropriate scale
• Flawless code quality: clean KISS structure, seeded for reproducibility, all imports used, correct pygal API
• Correct Imprint palette usage: green waveform, purple envelope, semantic red for peak transient
• Both themes render correctly with proper chrome adaptation — no dark-on-dark failures
• Idiomatic pygal: per-point dict tooltips, cubic interpolation, explicit canvas sizing
• Interactive HTML output with rich per-point tooltip labels (time + amplitude for each of 1200 points)

Weaknesses

• Zero reference line is somewhat subtle behind the dense waveform fill — could use a slightly higher stroke-width or brighter muted color to stand out more clearly
• Design excellence is moderate: while the color hierarchy and dashed envelope show intent, the chart retains pygal's default box frame and does not push into highly polished territory
• Data storytelling is functional but not exceptional: no annotations beyond the peak marker, envelope story is implicit rather than guided

Issues Found

1. VQ-03 MINOR: Zero reference line (INK_MUTED dashed) is slightly hard to isolate visually against the dense waveform fill — particularly on light render.
   • Fix: Increase zero-line stroke_style.width from 3.0 to 4.0–5.0, or use INK (full-contrast) instead of INK_MUTED to make it stand out more clearly.
2. DE-01/DE-02 MODERATE: Visual refinement is above default but chart retains full box frame and default pygal padding aesthetics.
   • Fix (optional for repair): Consider reducing margin asymmetry to give the data more breathing room, or increase margin_top to prevent any potential title crowding on scaled thumbnails.

AI Feedback for Next Attempt

Implementation is strong and APPROVED at 87/100. If repair is triggered: (1) increase zero reference line stroke width to ~5.0 and use INK color instead of INK_MUTED for better visibility through the waveform fill; (2) consider adding a subtle annotation near the peak marker showing the amplitude value to enhance storytelling. Core palette, canvas, theme adaptation, and spec compliance are all correct — do not change them.

Verdict: APPROVED