Plotting Sop

Before generating any figure, MUST check available capabilities. Run these checks silently (do not show output to user unless something fails):

Check 1: python3 -c "import matplotlib; print('matplotlib', matplotlib.__version__)"
Check 2: python3 -c "import seaborn; print('seaborn', seaborn.__version__)"
Check 3: which mmdc 2>/dev/null || npx --yes @mermaid-js/mermaid-cli mmdc --version 2>/dev/null
Check 4: python3 -c "import cairosvg; print('cairosvg OK')" 2>/dev/null

Record results in session memory. Do NOT repeat these checks for subsequent figures.

If matplotlib is missing (common on native macOS/WSL2 installs):

1. Tell user: "Python 科学绘图库未安装。是否允许我运行安装脚本？(约 30 秒)"
2. If user agrees: bash scripts/setup-plotting-env.sh
3. If setup script not found: pip install --user matplotlib seaborn numpy pandas
4. If user declines: skip Python Engine, use Mermaid or AI Image instead

If mmdc is missing: This is normal. Use npx --yes @mermaid-js/mermaid-cli mmdc as fallback. If npx also fails: save .mmd file and tell user to paste at https://mermaid.live

§2 Engine Selection Decision Tree

MUST follow this decision tree for every figure request. Do NOT skip steps.

User requests a figure
  │
  ├─ 1. Is it DATA VISUALIZATION (charts with numbers/statistics)?
  │    YES → §4 Python Engine
  │    Examples: bar chart, line plot, scatter, heatmap, violin, radar, histogram, box plot
  │
  ├─ 2. Is it a SIMPLE STRUCTURED DIAGRAM (≤15 nodes AND aesthetics not critical)?
  │    YES → §5 Mermaid Engine
  │    Examples: simple flowchart, sequence diagram, class diagram, Gantt chart
  │
  ├─ 3. Is it a COMPLEX diagram (>15 nodes OR requires visual polish)?
  │    (architecture diagram, research methodology flow, concept map,
  │     multi-layer system diagram, publication-quality illustration)
  │
  │    → Is NanoBanana/OpenRouter configured?
  │        YES → §6 AI Image Engine (NanoBanana)
  │        NO  → Recommend NanoBanana to user (see §3)
  │              → User provides API key? → §6 AI Image Engine
  │              → User declines?
  │                  → WARN: "本地引擎生成复杂流程图的质量有限，可能需要手动调整。"
  │                  → Fall back to §5 Mermaid Engine (best effort)
  │
  └─ 4. Is it a CUSTOM VECTOR graphic (geometric shapes, coordinate annotations)?
       YES → §7 SVG Engine

§3 NanoBanana Configuration Guide

NanoBanana provides access to Gemini's native image generation through OpenRouter. It is the only reliable path for complex, publication-quality academic diagrams because it generates images directly (pixel-level), bypassing code generation entirely.

Why recommend NanoBanana

• LLM-generated Mermaid/Python code for complex diagrams frequently has syntax errors
• Even when correct, code-rendered diagrams look mechanical and unprofessional
• Gemini image generation produces visually polished, publication-ready figures
• Low-IQ models benefit most: the API quality is independent of the local model's coding ability

Configuration

User needs to provide an OpenRouter API Key. Store in MEMORY.md under ## Global > ### Environment:

NanoBanana: configured
OpenRouter API Key: [stored in environment, not in memory]

Recommended model: google/gemini-2.5-flash-preview-image-generation Alternative model: google/gemini-2.5-pro-preview-image-generation API endpoint: https://openrouter.ai/api/v1/chat/completions

How to tell the user

When the user requests a complex diagram and NanoBanana is not configured:

"这类复杂的学术图表，推荐使用 NanoBanana（基于 Gemini 图片生成）来获得最佳效果。 您只需提供一个 OpenRouter API Key（https://openrouter.ai/settings/keys）。 如果您不想配置，我也可以使用本地工具（Mermaid/Python）尝试生成，但质量可能有限。"

§4 Python Engine — Data Visualization

For charts based on numerical data: bar, line, scatter, heatmap, violin, radar, box, histogram, pie, area, etc.

Output Path Resolution (MUST set before generating code)

Set output_path per §9 naming convention:

output_path = "outputs/figures/{topic}-fig{N}.png"

Example: outputs/figures/model-comparison-fig1.png

Code Template (MUST follow this structure)

The generated Python code MUST include all of the following elements. Low-IQ models: copy this template exactly, then fill in the plotting section.

import matplotlib
matplotlib.use('Agg')  # Non-interactive backend — MUST be before pyplot import
import matplotlib.pyplot as plt
import numpy as np

# ── Academic style settings ──────────────────────────────────
plt.rcParams.update({
    'font.family': 'sans-serif',
    'font.size': 12,
    'figure.dpi': 300,
    'axes.linewidth': 1.2,
    'axes.grid': True,
    'grid.alpha': 0.3,
    'legend.framealpha': 0.9,
})

fig, ax = plt.subplots(figsize=(10, 6))

# ── [YOUR PLOTTING CODE HERE] ───────────────────────────────
# Generate reasonable example data if user did not provide actual data.
# If using example data, add text annotation: "Example Data" in bottom-right.

# ── Labels and title (ALL ENGLISH) ──────────────────────────
ax.set_xlabel('X Label', fontsize=13)
ax.set_ylabel('Y Label', fontsize=13)
ax.set_title('Chart Title', fontsize=14, fontweight='bold')

# ── Save ─────────────────────────────────────────────────────
plt.tight_layout()
plt.savefig('{output_path}', format='png', dpi=300, bbox_inches='tight')
plt.close()
print('OK')

Execution Protocol

1. Generate code following the template above
2. Save code to temp file: system.run with inline Python or write to /tmp/rc_plot_{hash}.py
3. Execute: python3 /tmp/rc_plot_{hash}.py
4. Check result:
   • Exit code 0 AND "OK" in stdout AND output file exists → SUCCESS
   • Otherwise → FAILURE → enter ReAct loop

ReAct Self-Correction (max 3 attempts)

If execution fails:

Attempt 2-3: Inject the previous code and error into your next generation:

## Previous attempt FAILED. Fix the code.

### Previous code:
[paste the code that failed]

### Error output:
[paste stderr, truncated to 500 chars]

### Fix instructions:
- Analyze the error carefully
- Fix syntax errors, indentation, missing imports
- Ensure matplotlib.use('Agg') is BEFORE pyplot import
- Ensure savefig path is correct: {output_path}
- Do NOT use libraries that are not installed (stick to matplotlib, numpy, pandas, seaborn)

If all 3 attempts fail → inform user: "Python 作图失败。请检查数据格式或简化图表要求。"

Color Palettes (academic standard)

NEVER use red-green only contrast. Always use colorblind-safe palettes.

Chart Type Quick Reference

§5 Mermaid Engine — Structured Diagrams

For flowcharts, sequence diagrams, class diagrams, state machines, Gantt charts.

Supported Diagram Types

Syntax Rules (critical for low-IQ models)

1. Node IDs: use simple letters — A, B, C (NOT Chinese, NOT spaces)
2. Labels: wrap in [] — A[Start Process]
3. Arrows: --> or -->|label|
4. NEVER use these characters inside labels: &, <, >
5. For decision nodes (diamond shape): use single braces — C{Is valid?}
6. Keep diagrams ≤15 nodes AND aesthetics not critical. For larger or visually polished diagrams → recommend NanoBanana (§6).

Rendering Protocol

1. Generate Mermaid code
2. Save to temp file: /tmp/rc_mermaid_{hash}.mmd
3. Render (try in order):
   • mmdc -i /tmp/rc_mermaid_{hash}.mmd -o {output_path} -w 1920 -H 1080 --backgroundColor white
   • npx --yes @mermaid-js/mermaid-cli -i /tmp/rc_mermaid_{hash}.mmd -o {output_path}
   • Both fail → save .mmd file to workspace + tell user: "Mermaid 渲染工具未安装。已保存源文件，请粘贴到 https://mermaid.live 查看。"
4. Check result: file exists + size > 1KB → SUCCESS

ReAct for Mermaid

If mmdc returns an error:

• Parse the error message (usually "Parse error on line N")
• Fix the syntax issue (often: special characters in labels, missing brackets)
• Retry (max 3 attempts)

§6 AI Image Engine — NanoBanana (Complex Diagrams)

For complex academic diagrams that require visual polish: architecture diagrams, research methodology flows, concept maps, multi-layer system diagrams.

When to Use

• Diagram has >15 nodes or complex spatial layout
• User wants "美观/professional/publication-ready" quality
• User explicitly requests AI-generated figure
• Low-IQ model is active (AI Image quality is model-independent)

API Call Protocol

Step 0 — Confirm with user before calling the API (costs money):

"即将调用 NanoBanana (Gemini) 生成图片，预计消耗约 $0.01 API 额度。是否继续？" Wait for user confirmation. If user declines → fall back to §5 Mermaid.

Step 1 — Generate and execute a Python script via system.run:

import requests, base64, sys, os

API_KEY = os.environ.get('OPENROUTER_API_KEY', '')
if not API_KEY:
    print('ERROR: OPENROUTER_API_KEY not set', file=sys.stderr)
    sys.exit(1)

resp = requests.post(
    'https://openrouter.ai/api/v1/chat/completions',
    headers={
        'Authorization': f'Bearer {API_KEY}',
        'Content-Type': 'application/json',
    },
    json={
        'model': 'google/gemini-2.5-flash-preview-image-generation',
        'messages': [{
            'role': 'user',
            'content': 'Generate a professional academic diagram: {description}.\n\n'
                       'Style: clean, minimal, publication-ready, white background, '
                       'no watermark, clear English labels, professional color scheme '
                       '(blues, grays, muted tones), high resolution for academic paper.'
        }],
    },
    timeout=120,
)
resp.raise_for_status()
data = resp.json()

# Extract image from multimodal response
content = data['choices'][0]['message']['content']
b64_data = None
if isinstance(content, list):
    for part in content:
        if part.get('type') == 'image_url':
            url = part['image_url']['url']
            b64_data = url.split(',', 1)[1]
            break
        elif part.get('type') == 'image' and 'data' in part:
            b64_data = part['data']
            break
elif isinstance(content, str) and 'data:image' in content:
    b64_data = content.split(',', 1)[1]

if not b64_data:
    print('ERROR: No image found in API response', file=sys.stderr)
    sys.exit(1)

with open('{output_path}', 'wb') as f:
    f.write(base64.b64decode(b64_data))
print('OK')

Step 2 — Check: file exists + size > 1KB → SUCCESS.

If API call fails (timeout, auth error, quota exceeded):

• Log the error
• WARN user: "NanoBanana API 调用失败。降级到 Mermaid 引擎。"
• Fall back to §5 Mermaid Engine

§7 SVG Engine — Custom Vector Graphics

For geometric shapes, coordinate-annotated diagrams, simple custom illustrations.

Generation Method

Generate Python code using svgwrite:

import svgwrite

dwg = svgwrite.Drawing('{output_path}', size=('800px', '600px'))
dwg.add(dwg.rect(insert=(0, 0), size=('100%', '100%'), fill='white'))

# [YOUR SVG ELEMENTS HERE]

dwg.save()
print('OK')

If svgwrite is not available, generate raw SVG XML and save directly.

PNG conversion (optional):

• Try: python3 -c "import cairosvg; cairosvg.svg2png(url='{svg_path}', write_to='{png_path}', dpi=300)"
• If cairosvg unavailable: keep .svg file, inform user

§8 Quality Checklist (run after EVERY figure)

After generating a figure, MUST verify:

If checks fail → fix and re-run (counts as one ReAct iteration).

§9 Academic Figure Standards

File Naming

Save all figures to: outputs/figures/{topic}-fig{N}.{ext}

Examples:

• outputs/figures/transformer-fig1.png
• outputs/figures/model-comparison-fig2.png
• outputs/figures/methodology-flow-fig3.png

Caption Rule

Every figure MUST have an English caption. Present to user as:

Figure {N}. {Caption text describing what the figure shows.}

Citation Format

When embedding in text: "as shown in Figure {N}" or "see Figure {N}".

Style Rules

• Font: sans-serif (Arial, Helvetica), ≥ 10pt for all text
• DPI: 300 minimum (publication standard)
• Background: white (no transparency)
• Colors: colorblind-safe palettes (viridis, Set2, tab10, Paired)
• Borders: thin axis lines (1-1.5pt), no box frames around plots
• Grid: light gray (alpha 0.3), optional but recommended for data plots
• Legend: positioned to avoid overlapping data; semi-transparent background

§10 Integration with Writing SOP

When called from writing-sop Phase 2 (first draft generation):

1. Writing-sop identifies a section needs a figure
2. It invokes this skill (plotting-sop) with the figure description
3. This skill generates the figure → workspace_save to outputs/figures/
4. Return to writing-sop with: figure path + caption
5. Writing-sop embeds the figure reference in the draft

Pattern for inline invocation:

[Writing-sop Phase 2, writing Methods section]
→ "This section needs a methodology flowchart"
→ [Load plotting-sop] → Engine selection → Generate → Save
→ [Return to writing-sop] → "See Figure 1" inserted in text

RC Local Tools Reference