feat(letsplot): implement bode-basic

[github-actions]

Implementation: bode-basic - letsplot

Implements the letsplot version of bode-basic.

File: plots/bode-basic/implementations/letsplot.py

Parent Issue: #4411

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🤖 impl-generate workflow

[claude]

AI Review - Attempt 1/3

Image Description

The plot displays a dual-panel Bode plot. The top panel shows magnitude (dB) vs frequency (Hz) on a logarithmic x-axis, with a thick dark navy (#1B4F72) line tracing the frequency response of a second-order system. A dashed gray reference line sits at 0 dB. A green diamond marker indicates the gain crossover frequency at approximately 1 Hz. The bottom panel shows phase (°) vs frequency (Hz) with the same log x-axis and dark navy line. A dashed gray reference line marks -180°. A green diamond marker appears at the gain crossover frequency on the phase curve (~-111°), and a green label reads "PM = 68.9°" with a light green background. The title "bode-basic · letsplot · pyplots.ai" is centered and bold at the top. No gain margin annotation is shown because the chosen 2nd-order system's phase never crosses -180°.

Score: 80/100

Category	Score	Max
Visual Quality	26	30
Design Excellence	12	20
Spec Compliance	13	15
Data Quality	12	15
Code Quality	10	10
Library Mastery	7	10
Total	80	100

Visual Quality (26/30)

• VQ-01: Text Legibility (7/8) - Font sizes explicitly set (title=26, axis_title=20, axis_text=16), all clearly readable
• VQ-02: No Overlap (6/6) - No overlapping elements anywhere
• VQ-03: Element Visibility (5/6) - Lines thick (size=2.5), markers visible (size=8), but phase margin segment barely visible against curve
• VQ-04: Color Accessibility (4/4) - Navy and green are colorblind-distinguishable, good contrast against white
• VQ-05: Layout & Canvas (2/4) - Magnitude plot has excessive negative space at bottom (y-axis extends to -70 dB); panels could use more vertical space
• VQ-06: Axis Labels & Title (2/2) - "Magnitude (dB)", "Phase (°)", "Frequency (Hz)" — all descriptive with units

Design Excellence (12/20)

• DE-01: Aesthetic Sophistication (5/8) - Custom color palette, flavor_high_contrast_light theme, styled label backgrounds (#EAFAF1), intentional color coding (green=PM). Above defaults but not publication-level polish
• DE-02: Visual Refinement (4/6) - Grid customized (#E0E0E0, size=0.3), minor grid removed, axis lines styled (#BBBBBB), margins set. Good refinement
• DE-03: Data Storytelling (3/6) - Phase margin annotation and crossover markers create some narrative, but missing gain margin weakens the story. Resonance peak barely visible

Spec Compliance (13/15)

• SC-01: Plot Type (5/5) - Correct dual-panel Bode plot with magnitude on top, phase on bottom, shared log frequency axis
• SC-02: Required Features (2/4) - Phase margin annotated with label and marker. Reference lines at 0 dB and -180° present. BUT gain margin annotation is missing because the 2nd-order system's phase never crosses -180°. Spec explicitly requires both margin annotations
• SC-03: Data Mapping (3/3) - Frequency on x (log scale), magnitude in dB on top y, phase in degrees on bottom y — all correct
• SC-04: Title & Legend (3/3) - Title format "bode-basic · letsplot · pyplots.ai" correct. No legend needed for single-series

Data Quality (12/15)

• DQ-01: Feature Coverage (3/6) - Shows phase margin and gain crossover, but does NOT demonstrate gain margin (a key Bode plot feature). The 2nd-order system (zeta=0.4) has infinite gain margin since phase asymptotically approaches -180°. A higher-order system would show both margins. Resonance peak (~2.6 dB) is too subtle to be visually meaningful
• DQ-02: Realistic Context (5/5) - Second-order underdamped system G(s)=25/(s²+4s+25) is a classic, neutral control systems example
• DQ-03: Appropriate Scale (4/4) - Frequency range (0.1-50 Hz), magnitude (-70 to +5 dB), phase (0 to -180°) all sensible for this system

Code Quality (10/10)

• CQ-01: KISS Structure (3/3) - Clean imports → data → plot → save structure, no functions or classes
• CQ-02: Reproducibility (2/2) - Deterministic data from scipy.signal.TransferFunction, no randomness
• CQ-03: Clean Imports (2/2) - All imports used: numpy, pandas, lets_plot, export_ggsave, scipy.signal
• CQ-04: Code Elegance (2/2) - Well-structured, appropriate complexity, interpolation for crossover points is clean
• CQ-05: Output & API (1/1) - Saves as plot.png with scale=3, also exports HTML

Library Mastery (7/10)

• LM-01: Idiomatic Usage (4/5) - Good use of ggplot grammar, aes mappings, theme composition, geom layering
• LM-02: Distinctive Features (3/5) - Uses layer_tooltips (letsplot-specific interactive hover), ggbunch for multi-panel layout, flavor_high_contrast_light() built-in theme

Score Caps Applied

• None

Strengths

• Clean, well-structured code with proper crossover interpolation logic
• Good use of letsplot-specific features (layer_tooltips, ggbunch, flavor_high_contrast_light)
• Custom color palette with intentional color coding (red=gain margin, green=phase margin)
• Proper reference lines at 0 dB and -180°
• Deterministic data from scipy transfer function

Weaknesses

• Missing gain margin demonstration — The chosen 2nd-order system has infinite gain margin (phase never crosses -180°), so this required spec feature is never shown. Use a higher-order system (e.g., 3rd order with a finite gain margin) to demonstrate both margins
• Magnitude plot layout — Excessive negative space below the curve; y-axis range extends far below the data, wasting vertical space
• Resonance peak barely visible — The ~2.6 dB resonance peak for zeta=0.4 is too subtle at this scale to be a meaningful visual feature

Issues Found

1. SC-02 / DQ-01: Gain margin annotation missing due to data choice
   • Fix: Use a 3rd-order or higher system where phase crosses -180° at a finite frequency, demonstrating both gain margin and phase margin
2. VQ-05: Magnitude panel has too much unused vertical space
   • Fix: Constrain y-axis limits on magnitude plot to focus on the relevant range (e.g., -40 to +10 dB), or choose a system that uses more of the magnitude range
3. DE-03: Data storytelling could be stronger
   • Fix: With both margins visible, use color-coded annotations and segments to tell a clear stability story

AI Feedback for Next Attempt

Use a higher-order transfer function (e.g., 3rd or 4th order) so that the phase crosses -180° and the gain margin can be annotated alongside the phase margin. Tighten the magnitude y-axis limits to reduce wasted space. Consider adding the phase margin dotted segment more visibly (thicker or different style). These changes will improve both spec compliance and data storytelling.

Verdict: REJECTED

[github-actions]

🔧 Repair Attempt 1/3

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

The plot displays a dual-panel Bode plot. The top panel shows Magnitude (dB) vs Frequency (Hz) on a logarithmic x-axis, with a dark navy blue (#1B4F72) curve that starts near 0 dB, shows a very subtle resonance peak around 0.8 Hz (barely rising above 0 dB), then rolls off steeply to about -40 dB. A dashed gray reference line sits at 0 dB. A green diamond marks the gain crossover point on the 0 dB line, and a red "GM = 9.3 dB" label with pink background is positioned to its right. The bottom panel shows Phase (°) vs Frequency (Hz), with the same navy curve transitioning from 0° down to approximately -270°. A dashed gray reference line sits at -180°. A red diamond marks the phase crossover point at -180°, and a green "PM = 34.9°" label with light green background appears nearby. The title "bode-basic · letsplot · pyplots.ai" is centered at the top in bold. Both panels use subtle gray grid lines on a white background with the high-contrast theme.

Score: 84/100

Category	Score	Max
Visual Quality	25	30
Design Excellence	13	20
Spec Compliance	15	15
Data Quality	14	15
Code Quality	10	10
Library Mastery	7	10
Total	84	100

Visual Quality (25/30)

• VQ-01: Text Legibility (7/8) - Font sizes explicitly set (title=26, axis_title=20, axis_text=16); annotation labels at size=14 are slightly small relative to other text
• VQ-02: No Overlap (6/6) - All text elements well-separated, no collisions
• VQ-03: Element Visibility (5/6) - Main curves thick (size=2.5) and markers visible (size=8), but the margin indicator dotted segments are barely visible
• VQ-04: Color Accessibility (2/4) - Red (#C0392B) for GM and green (#27AE60) for PM is the classic problematic red-green combination for colorblind users (deuteranopia/protanopia)
• VQ-05: Layout & Canvas (3/4) - Dual panel fills canvas reasonably but some wasted space at high frequencies where the curve has already rolled off
• VQ-06: Axis Labels & Title (2/2) - All labels include units: "Magnitude (dB)", "Phase (°)", "Frequency (Hz)"

Design Excellence (13/20)

• DE-01: Aesthetic Sophistication (5/8) - Custom color palette (navy, red, green), flavor_high_contrast_light() theme, styled annotation labels with colored backgrounds — above defaults but not publication-ready
• DE-02: Visual Refinement (4/6) - Subtle grid (#E0E0E0), minor grid removed, custom axis lines, generous margins — good refinement but not fully polished
• DE-03: Data Storytelling (4/6) - GM and PM annotations with colored labels create clear focal points; reference lines at 0 dB and -180° provide engineering context; visual hierarchy guides the viewer to stability margins

Spec Compliance (15/15)

• SC-01: Plot Type (5/5) - Correct dual-panel Bode plot with magnitude on top, phase on bottom
• SC-02: Required Features (4/4) - All spec features present: dual panels, shared log frequency axis, reference lines at 0 dB and -180°, GM and PM annotations with markers, grid lines
• SC-03: Data Mapping (3/3) - X=frequency (Hz, log10 scale), Y=magnitude (dB) and phase (°), all data visible
• SC-04: Title & Legend (3/3) - Title "bode-basic · letsplot · pyplots.ai" in correct format; no legend needed for single-series

Data Quality (14/15)

• DQ-01: Feature Coverage (5/6) - Shows resonance peak, gain/phase margins, high-frequency rolloff, full phase transition from 0° to -270°; however the resonance peak is very subtle (barely above 0 dB), making it hard to appreciate visually
• DQ-02: Realistic Context (5/5) - Realistic 3rd-order transfer function G(s)=500/((s+20)(s²+3s+25)) from control systems engineering with physically meaningful parameters
• DQ-03: Appropriate Scale (4/4) - Frequency range 0.016-50 Hz appropriate, GM≈9.3 dB and PM≈35° are realistic stability margins for a control system

Code Quality (10/10)

• CQ-01: KISS Structure (3/3) - Clean imports → data → plot → save structure with no functions or classes
• CQ-02: Reproducibility (2/2) - Fully deterministic: fixed transfer function coefficients, no randomness
• CQ-03: Clean Imports (2/2) - All imports used (numpy, pandas, lets_plot, scipy.signal)
• CQ-04: Code Elegance (2/2) - Well-organized code with appropriate complexity; conditional annotations handled cleanly
• CQ-05: Output & API (1/1) - Saves as plot.png with scale=3, uses current API

Library Mastery (7/10)

• LM-01: Idiomatic Usage (4/5) - Good use of ggplot grammar, proper theme composition with +, aes mappings, and geom layering
• LM-02: Distinctive Features (3/5) - Uses lets-plot-specific features: layer_tooltips() for interactive hover, flavor_high_contrast_light() theme, ggbunch() for multi-panel layout, geom_label with label_padding/label_r, HTML export

Score Caps Applied

• None

Strengths

• Full spec compliance with all required Bode plot features including GM/PM annotations with clear labeled indicators
• Realistic transfer function data from scipy.signal providing authentic frequency response curves
• Good use of lets-plot distinctive features: ggbunch for dual panels, layer_tooltips for interactivity, flavor_high_contrast_light theme
• Professional annotation labels with colored backgrounds and bold text create clear visual focal points
• Clean, well-structured code with deterministic data generation

Weaknesses

• Red-green color combination for GM/PM annotations fails colorblind accessibility (VQ-04)
• Resonance peak is very subtle and barely visible above 0 dB, reducing visual interest and feature demonstration
• Margin indicator dotted segments are hard to see — they need to be more prominent

Issues Found

1. VQ-04 LOW: Red (#C0392B) for GM and green (#27AE60) for PM is a classic colorblind-unfriendly combination
   • Fix: Replace with colorblind-safe alternatives, e.g., use blue (#2471A3) for PM and orange (#E67E22) for GM, or dark red (#922B21) and teal (#1ABC9C)
2. VQ-03 MEDIUM: Margin dotted segments between reference lines and crossover points are barely visible
   • Fix: Increase segment size or change linetype to make them more prominent
3. DQ-01 MINOR: Resonance peak is barely visible above 0 dB
   • Fix: Adjust system parameters to produce a more pronounced resonance peak (e.g., lower damping ratio or adjust gain)

AI Feedback for Next Attempt

Fix the colorblind accessibility issue by replacing red/green GM/PM colors with a colorblind-safe pair (e.g., blue/orange or dark red/teal). Make the margin indicator segments more visible by increasing their size or using a more prominent linetype. Consider adjusting the transfer function parameters to produce a more visible resonance peak that better demonstrates the Bode plot's ability to reveal resonance behavior.

Verdict: REJECTED

[github-actions]

🔧 Repair Attempt 2/3

Applied fixes based on AI review feedback.

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

---

🤖 impl-repair

[claude]

AI Review - Attempt 3/3

Image Description

The plot displays a dual-panel Bode plot for frequency response analysis. The top panel shows magnitude (dB) vs. frequency (Hz) on a logarithmic x-axis, with a dark navy blue (#1B4F72) line that stays near 0 dB with a very subtle resonance bump around 0.5-1 Hz, then rolls off steeply to about -45 dB. A dashed gray reference line at 0 dB is present. An orange diamond marker and an orange-bordered label box reading "GM = 7.9 dB" annotate the gain margin. A blue diamond marks the gain crossover point on the 0 dB line. The bottom panel shows phase (°) vs. frequency (Hz), also on a log x-axis. The dark navy line starts near 0° and rolls off to about -270°. A dashed gray reference line at -180° is drawn. A blue-bordered label box reads "PM = 27.1°" with an orange diamond at the phase crossover point on the -180° line. The title "bode-basic · letsplot · pyplots.ai" appears centered at the top in bold. All axis labels include units: "Magnitude (dB)", "Phase (°)", "Frequency (Hz)". The background is clean with subtle gray major gridlines.

Score: 85/100

Category	Score	Max
Visual Quality	26	30
Design Excellence	13	20
Spec Compliance	15	15
Data Quality	14	15
Code Quality	10	10
Library Mastery	7	10
Total	85	100

Visual Quality (26/30)

• VQ-01: Text Legibility (7/8) - All font sizes explicitly set (title=26, axis_title=20 bold, axis_text=16, labels=16 bold). Readable at full resolution. Annotation label text could be slightly larger for the canvas size.
• VQ-02: No Overlap (5/6) - No text-on-text overlap. The GM label box is large and positioned near the 0 dB reference line, slightly crowding that area, but all text remains readable.
• VQ-03: Element Visibility (5/6) - Lines at size=2.5 are bold and clearly visible. Diamond markers (size=10, shape=18) are visible. The gain margin dashed segment is short relative to the y-axis range and not as prominent as the label.
• VQ-04: Color Accessibility (4/4) - Colorblind-safe palette: dark navy, orange, blue. No red-green distinction relied upon.
• VQ-05: Layout & Canvas (3/4) - Two-panel layout via ggbunch works well. Panels fill the canvas reasonably, but some unused space on the right side of both panels where frequencies thin out.
• VQ-06: Axis Labels & Title (2/2) - All labels include units: "Magnitude (dB)", "Phase (°)", "Frequency (Hz)".

Design Excellence (13/20)

• DE-01: Aesthetic Sophistication (5/8) - Uses flavor_high_contrast_light() theme with a custom colorblind-safe color palette. Styled annotation boxes with colored fills (#FDEBD0, #D4E6F1) and bold text. Above configured defaults but not publication-level polish.
• DE-02: Visual Refinement (4/6) - Minor grid suppressed (element_blank), major grid subtle (#E0E0E0, size=0.3), axis lines styled (#BBBBBB, size=0.5), generous margins set. Good refinement but spines still present.
• DE-03: Data Storytelling (4/6) - Annotations for GM and PM directly guide the viewer to the key engineering insights. Color-coded annotations (orange for gain margin, blue for phase margin) create a clear visual correspondence between the two panels. The viewer immediately understands the stability margins.

Spec Compliance (15/15)

• SC-01: Plot Type (5/5) - Correct dual-panel Bode plot with magnitude on top and phase on bottom.
• SC-02: Required Features (4/4) - All spec features present: dual-panel layout ✓, gain margin annotation ✓, phase margin annotation ✓, reference lines at 0 dB and -180° ✓, logarithmic frequency axis ✓, grid lines ✓.
• SC-03: Data Mapping (3/3) - Frequency on x-axis (log10), magnitude in dB on top y-axis, phase in degrees on bottom y-axis. All correct.
• SC-04: Title & Legend (3/3) - Title "bode-basic · letsplot · pyplots.ai" in correct format. No legend needed for single-series plot; annotation labels serve the purpose.

Data Quality (14/15)

• DQ-01: Feature Coverage (5/6) - Shows resonance peak (subtle), steep rolloff, phase transition, gain margin, and phase margin. The resonance peak (~6 dB) is not visually prominent due to the y-axis range extending to -40 dB.
• DQ-02: Realistic Context (5/5) - Uses a realistic 3rd-order transfer function G(s) = 500/((s+20)(s²+2.6s+25)) from control systems engineering. Parameters produce meaningful GM (7.9 dB) and PM (27.1°).
• DQ-03: Appropriate Scale (4/4) - Frequency range 0.016-50 Hz appropriate for the system dynamics. Magnitude range -40 to ~6 dB and phase range 0° to -270° are realistic.

Code Quality (10/10)

• CQ-01: KISS Structure (3/3) - Follows imports → data → plot → save. No functions or classes. Linear flow.
• CQ-02: Reproducibility (2/2) - Fully deterministic: transfer function coefficients and logspace frequencies, no randomness.
• CQ-03: Clean Imports (2/2) - All imports used: numpy, pandas, lets_plot, export_ggsave, scipy.signal.
• CQ-04: Code Elegance (2/2) - Clean interpolation for crossover calculations. Appropriate complexity for the engineering visualization. No fake UI or over-engineering.
• CQ-05: Output & API (1/1) - Saves as plot.png via export_ggsave with scale=3. Also exports HTML.

Library Mastery (7/10)

• LM-01: Idiomatic Usage (4/5) - Good use of ggplot grammar: aes mappings, geom layers, scale_x_log10, labs, theme customization. Uses ggbunch for multi-panel composition. Follows lets-plot patterns well.
• LM-02: Distinctive Features (3/5) - Uses lets-plot specific features: flavor_high_contrast_light() theme flavor, layer_tooltips() with custom formatting for interactive hover info, ggbunch for panel layout, HTML export alongside PNG.

Score Caps Applied

• None applied

Strengths

• Full spec compliance: all required features (dual-panel, margins, reference lines, log axis, grid) are present and correct
• Realistic engineering data with a well-chosen 3rd-order transfer function producing meaningful stability margins
• Color-coded annotations (orange=GM, blue=PM) create clear visual correspondence between panels
• Clean, deterministic code with appropriate use of scipy.signal for Bode computation
• Uses lets-plot distinctive features: flavor themes, layer_tooltips, ggbunch, HTML export

Weaknesses

• The resonance peak (~6 dB) is barely visible due to the wide y-axis range (-40 to +6 dB)
• Gain margin dashed segment is short and not visually prominent compared to the label box
• Axis spines are still present (only styled, not removed) limiting visual refinement score

Issues Found

1. DQ-01 MINOR: Resonance peak not visually prominent — the ~6 dB peak is dwarfed by the -40 dB y-axis range
   • Fix: Consider tighter y-axis limits or a break in the axis to emphasize the peak
2. DE-02 MINOR: Spines still visible — axis lines are styled but not removed
   • Fix: Remove top/right spines for a cleaner look
3. VQ-03 MINOR: Gain margin segment barely visible — the dashed orange line between 0 dB and ~-7.9 dB is hard to see
   • Fix: Increase segment thickness or add arrowheads

AI Feedback for Next Attempt

Solid implementation with full spec compliance and good engineering data. To reach 90+: (1) make the resonance peak more visually prominent, (2) remove top/right spines for cleaner design, (3) make the gain margin segment more visually distinct. The annotation styling and color-coding across panels is well done.

Verdict: REJECTED

[github-actions]

🔧 Repair Attempt 3/3

Applied fixes based on AI review feedback.

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

---

🤖 impl-repair

[claude]

AI Review - Attempt 3/3

Image Description

The plot displays a Bode plot with two vertically aligned panels on a white background. The top panel shows magnitude (dB) vs frequency (Hz) on a logarithmic x-axis. A thick dark navy blue line (#1B4F72) starts flat near 0 dB, exhibits a subtle resonance peak around 0.5–0.8 Hz, then drops steeply through -35 dB. A dashed gray reference line marks 0 dB. The gain margin (GM = 5.4 dB) is annotated with an orange (#D35400) label on a light peach background, with orange diamond markers at the phase crossover frequency (~1.2 Hz) and a vertical arrow segment between 0 dB and the magnitude at that frequency. A blue diamond marks the gain crossover on the 0 dB line. The bottom panel shows phase (°) vs frequency (Hz) on the same log scale. The dark blue line starts near 0° and rolls off steeply through -180° to below -250°. A dashed gray reference line marks -180°. The phase margin (PM = 15.8°) is annotated with a blue (#2471A3) label on a light blue background, with blue diamond markers and a vertical arrow segment showing the margin between the phase at gain crossover and -180°. An orange diamond marks the phase crossover point at -180°. Dotted vertical lines connect the crossover frequencies across both panels. The title "bode-basic · letsplot · pyplots.ai" is centered at the top in bold. Axis labels include "Magnitude (dB)", "Phase (°)", and "Frequency (Hz)" with units.

Score: 90/100

Category	Score	Max
Visual Quality	28	30
Design Excellence	14	20
Spec Compliance	15	15
Data Quality	15	15
Code Quality	10	10
Library Mastery	8	10
Total	90	100

Visual Quality (28/30)

• VQ-01: Text Legibility (8/8) - All font sizes explicitly set: title=26pt, axis_title=20pt bold, axis_text=16pt, labels=18pt bold. All text clearly readable.
• VQ-02: No Overlap (6/6) - No overlapping text. GM/PM labels well-positioned away from data and markers.
• VQ-03: Element Visibility (5/6) - Main curve thick (size=2.5) and clearly visible. Diamond markers (size=10) prominent. GM/PM arrow segments are small due to narrow margins (~5.4 dB, ~15.8°) but still visible.
• VQ-04: Color Accessibility (4/4) - Colorblind-safe palette: dark navy blue (#1B4F72) for main line, orange (#D35400) for GM, blue (#2471A3) for PM. No red-green dependency.
• VQ-05: Layout & Canvas (3/4) - Dual-panel layout fills canvas well via ggbunch. Minor: magnitude y-axis truncated at -35 dB (intentional but loses some rolloff), and right portion of log scale has less data density.
• VQ-06: Axis Labels & Title (2/2) - "Magnitude (dB)", "Phase (°)", "Frequency (Hz)" — all descriptive with units.

Design Excellence (14/20)

• DE-01: Aesthetic Sophistication (6/8) - Strong design: custom colorblind-safe palette with intentional color coding (orange=GM, blue=PM), flavor_high_contrast_light() base with custom overrides, colored label backgrounds (#FDEBD0, #D4E6F1), diamond markers (shape=18), bold typography. Clearly above defaults.
• DE-02: Visual Refinement (4/6) - Panel border removed, subtle grid (#E0E0E0, size=0.3), minor grid hidden, light axis lines (#AAAAAA), generous margins (30,30,10,20). Good refinement visible.
• DE-03: Data Storytelling (4/6) - Plot tells a clear stability story: GM and PM annotations serve as focal points, color-coded to distinguish the two margins. Viewer immediately understands the system's stability characteristics. Visual hierarchy guides interpretation.

Spec Compliance (15/15)

• SC-01: Plot Type (5/5) - Correct Bode plot with dual-panel layout (magnitude on top, phase on bottom).
• SC-02: Required Features (4/4) - All features present: dual panels, shared log frequency axis, 0 dB reference line, -180° reference line, gain margin annotation, phase margin annotation, grid lines.
• SC-03: Data Mapping (3/3) - Frequency on X (log scale), magnitude/phase on Y. All data visible across the relevant range.
• SC-04: Title & Legend (3/3) - Title "bode-basic · letsplot · pyplots.ai" in correct format, centered, bold. No legend needed (single series with color-coded annotations).

Data Quality (15/15)

• DQ-01: Feature Coverage (6/6) - Shows all key Bode plot features: resonance peak, high-frequency rolloff, gain crossover, phase crossover, gain margin, phase margin, asymptotic behavior.
• DQ-02: Realistic Context (5/5) - 3rd-order transfer function G(s)=500/((s+20)(s²+2s+25)) is a realistic control systems scenario with complex poles (ζ=0.2, ωn=5) giving a prominent resonance. Neutral engineering domain.
• DQ-03: Appropriate Scale (4/4) - Realistic frequency range (0.1–50 Hz), physically meaningful margins (GM≈5.4 dB, PM≈15.8°), sensible system parameters for a marginally stable system.

Code Quality (10/10)

• CQ-01: KISS Structure (3/3) - Linear script: imports → transfer function → frequency response → annotations → plots → save. No functions/classes.
• CQ-02: Reproducibility (2/2) - Fully deterministic: analytical transfer function with scipy.signal.bode, no random data.
• CQ-03: Clean Imports (2/2) - All imports used: numpy, pandas, lets_plot, export_ggsave, scipy.signal.
• CQ-04: Code Elegance (2/2) - Clean, well-structured. Interpolation for crossover frequencies is appropriate. No fake UI or over-engineering.
• CQ-05: Output & API (1/1) - Saves as plot.png via export_ggsave with scale=3. Current API usage.

Library Mastery (8/10)

• LM-01: Idiomatic Usage (4/5) - Expert use of lets-plot gg grammar: ggplot/aes, geom_line/geom_hline/geom_segment/geom_point/geom_label, scale_x_log10, labs, theme composition. ggbunch for multi-panel layout is the canonical lets-plot approach.
• LM-02: Distinctive Features (4/5) - Leverages lets-plot-specific features not available in plotnine: flavor_high_contrast_light() theme flavor, layer_tooltips() builder with .format()/.line() chains, ggbunch with region tuples for precise panel positioning, export_ggsave with scale parameter.

Score Caps Applied

• None — no caps triggered.

Strengths

• Excellent spec compliance with all required Bode plot features (dual panels, margins, reference lines, annotations)
• Strong design choices: color-coded stability margins (orange GM, blue PM) with labeled backgrounds create clear visual hierarchy
• Realistic 3rd-order transfer function with meaningful engineering parameters (resonance, marginal stability)
• Expert lets-plot usage with distinctive features (flavor_high_contrast_light, layer_tooltips, ggbunch)
• Clean, deterministic code with well-structured interpolation for precise crossover calculations

Weaknesses

• GM/PM arrow segments are small relative to plot scale due to narrow margins, reducing their visual impact
• Right portion of log-scale frequency axis has less data density, creating some visual imbalance
• Could benefit from slightly more whitespace between the two panels

Issues Found

None — implementation meets all quality thresholds.

AI Feedback for Next Attempt

Implementation has reached publication quality. The color-coded stability margin annotations, clean dual-panel layout, and expert lets-plot usage combine effectively. Minor improvements could include enlarging the margin arrow segments or adding asymptotic slope lines for additional engineering context, but these are not required.

Verdict: APPROVED