figure-generator

name	figure-generator
description	Generates figures from placeholders in .tex files. Creates Python matplotlib scripts for data figures, TikZ/Python schematics for diagrams. Maintains a shared plot_defaults.py for consistent styling. Flags complex figures for the user. Runs after the writer skill.
allowed-tools	["Read","Write","Edit","Bash","Task"]

Figure Generator

This skill is intended to run with the image-output output style, which ships with this plugin. If your system prompt does not contain the line IO-CANARY-8e05, append this to your response to the author:

This skill is intended to be used with the image-output output style. It is included in the plugin. Ask me to set it up in your user Claude settings, or select it yourself under Output style in Claude's /config.

Overview

This skill runs after the writer skill has produced LaTeX prose. It reads .tex files, finds figure placeholder blocks in the ../writer/references/figure-placeholder.md format, and generates actual figures where possible. It replaces each placeholder with \includegraphics{...} pointing to generated output.

Plot Defaults File

Before generating any figures, check for plot_defaults.py at the project root. If it does not exist, create it. This file defines all shared styling for consistency across the entire thesis.

# plot_defaults.py
# Shared matplotlib defaults for all thesis figures.
# Edit this file to change styling globally.

import matplotlib.pyplot as plt
import matplotlib as mpl

# --- Colour palette ---
COLOURS = {
    'primary': '#1f77b4',
    'secondary': '#ff7f0e',
    'tertiary': '#2ca02c',
    'quaternary': '#d62728',
    'grey': '#7f7f7f',
    'light_grey': '#c7c7c7',
}
COLOUR_CYCLE = [COLOURS['primary'], COLOURS['secondary'], COLOURS['tertiary'],
                COLOURS['quaternary'], COLOURS['grey']]

# --- Figure sizes (inches) ---
SINGLE_COL = (6.5, 4.0)
DOUBLE_COL = (6.5, 3.0)    # wide but short
HALF_COL = (3.15, 3.0)     # for subfigures

# --- Font and text ---
FONT_FAMILY = 'serif'
FONT_SIZE = 12
LABEL_SIZE = 12
TICK_SIZE = 11
LEGEND_SIZE = 11

# --- Line and marker ---
LINE_WIDTH = 1.5
MARKER_SIZE = 4

# --- Export ---
DPI = 300
FORMATS = ['pdf', 'png']  # pdf for LaTeX, png for preview


def apply():
    """Apply thesis defaults to matplotlib rcParams."""
    mpl.rcParams.update({
        'font.family': FONT_FAMILY,
        'font.size': FONT_SIZE,
        'axes.labelsize': LABEL_SIZE,
        'axes.titlesize': LABEL_SIZE,
        'xtick.labelsize': TICK_SIZE,
        'ytick.labelsize': TICK_SIZE,
        'legend.fontsize': LEGEND_SIZE,
        'figure.figsize': SINGLE_COL,
        'figure.dpi': DPI,
        'savefig.dpi': DPI,
        'savefig.bbox': 'tight',
        'lines.linewidth': LINE_WIDTH,
        'lines.markersize': MARKER_SIZE,
        'axes.prop_cycle': mpl.cycler(color=COLOUR_CYCLE),
    })


def savefig(fig, path_stem):
    """Save figure in all configured formats."""
    for fmt in FORMATS:
        fig.savefig(f'{path_stem}.{fmt}', dpi=DPI, bbox_inches='tight')


def write_tikz_colours(path='tikz_colours.tex'):
    """Emit the shared palette as \\definecolor lines for TikZ figures."""
    with open(path, 'w', encoding='utf-8') as handle:
        for name, value in COLOURS.items():
            handle.write(f'\\definecolor{{{name}}}{{HTML}}{{{value.lstrip("#").upper()}}}\n')

Every render.py must:

1. import plot_defaults; plot_defaults.apply() at the top
2. Take its output stem as sys.argv[1] and export with plot_defaults.savefig(fig, sys.argv[1])
3. Reference plot_defaults.COLOURS, plot_defaults.SINGLE_COL, etc. for sizing and colours

Generate at the width the figure is placed at. A figure generated wider than its \includegraphics width is scaled down by LaTeX, which shrinks every label below the size plot_defaults set. No font size in this file may drop below 11.

Figure Categories

A placeholder supplies the data source path (CSV, HDF5, or a reference to the code that produces the data), the plot type, the axes labels and units, and the features the plan requires the figure to show.

Each generated figure produces:

• a directory named for the figure, beside the .tex that uses it, holding one render.py
• fig/<name>.pdf and fig/<name>.png in that .tex's own fig/ directory
• the .tex placeholder replaced by \includegraphics{fig/<name>}

Use matplotlib, not seaborn. Schematics go through TikZ instead, with render.tex in place of render.py; see below.

Project layout

Nothing registers a figure. Creating the directory is what adds it.

plot_defaults.py            shared matplotlib styling
tikz_defaults.tex           shared TikZ preamble
tikz_colours.tex            generated from plot_defaults.COLOURS
build_figures.py            builds every figure it discovers

chapters/03-methods/
    methods.tex             \includegraphics{fig/settling_time}
    settling_time/
        render.py
    control_loop/
        render.tex
    fig/                    generated; never edited by hand
        settling_time.pdf
        settling_time.png
        control_loop.pdf
        control_loop.png

A figure directory holds exactly one entry point. render.py and render.tex in the same directory is an error, not a choice.

Where a figure cannot be generated, keep the placeholder and add a % TODO: MANUAL FIGURE REQUIRED comment naming what is needed and why.

TikZ Figures

Schematics are standalone LaTeX documents, never inline tikzpicture blocks. Each compiles on its own, so there is a file to open and hand to the reviewer before it reaches the chapter.

Shared preamble

tikz_defaults.tex at the project root is the preamble every schematic inputs. Create it if absent. If it exists, respect the author's choices: add missing entries, never overwrite existing ones.

% tikz_defaults.tex
\usepackage{tikz}
\usepackage{siunitx}
\usetikzlibrary{arrows.meta, positioning, calc}

\input{tikz_colours}   % generated by plot_defaults.write_tikz_colours()

\tikzset{
  every node/.style={font=\fontsize{12}{14}\selectfont},
  block/.style={draw, rectangle, minimum height=1cm, minimum width=1.5cm},
  signal/.style={-{Stealth[length=2mm]}, line width=1.5pt},
}

Font family and base size here must match the thesis body text, and the node font size must match plot_defaults.FONT_SIZE. A standalone document inherits nothing from the thesis preamble.

Colours come from plot_defaults.COLOURS through plot_defaults.write_tikz_colours(), so one palette change reaches both pipelines. plot_defaults.py is canonical; tikz_colours.tex is generated and never hand-edited.

Figure document

% chapters/03-methods/control_loop/render.tex
\documentclass[12pt,border=2pt]{standalone}
\input{tikz_defaults}
\begin{document}
\begin{tikzpicture}
  \node[block] (ctrl) {Controller};
  \node[block, right=2cm of ctrl] (plant) {Plant};
  \draw[signal] (ctrl) -- (plant);
\end{tikzpicture}
\end{document}

The standalone class crops to the drawing, so it is emitted at its natural size. Size the drawing to its placement width: a schematic scaled down by \includegraphics loses label size exactly as a plot does.

Build

build_figures.py ships with this skill under scripts/. Copy it to the project root on first use, alongside plot_defaults.py and tikz_defaults.tex.

It walks the project, finds every directory holding a render.py or render.tex, and writes the outputs into the fig/ directory beside that figure directory's parent. A render.py is run with the project root on PYTHONPATH and its output stem as sys.argv[1], so import plot_defaults resolves and plot_defaults.savefig writes both formats. A render.tex is compiled with pdflatex with the project root on TEXINPUTS, so the bare \input{tikz_defaults} resolves, then rasterised to PNG at plot_defaults.DPI.

The chapter includes the PDF. The PNG exists for the render inspection and the reviewer pass.

python build_figures.py              build what is stale
python build_figures.py --force      rebuild everything
python build_figures.py --only NAME  build one figure
python build_figures.py --list       list what was discovered

A figure rebuilds when any file in its directory is newer than its PDF, or when plot_defaults.py, tikz_defaults.tex, or tikz_colours.tex changed. tikz_colours.tex is only rewritten when the palette actually changed, so an unchanged palette does not force a rebuild. Exit status is 1 if any figure failed and 2 if the layout is malformed; a failure reports the underlying traceback or LaTeX log and does not stop the other figures.

Workflow

1. Check defaults: read or create plot_defaults.py, tikz_defaults.tex, and build_figures.py at the project root.
2. Scan: read the .tex file(s) and find every figure placeholder block.
3. Generate: create the figure directory, write its render.py or render.tex, run build_figures.py --only <name>, and open the PNG it produced.
4. Resolve: fix every defect visible in the render, then rebuild.
5. Review: send the reviewer agent the render and the placeholder's brief. Resolve its findings and rebuild until a pass returns nothing.
6. Place: replace the placeholder with \includegraphics{fig/<name>}, or add the % TODO: MANUAL FIGURE REQUIRED comment where the figure could not be generated.
7. Report: what was generated, what was flagged, what failed.

LaTeX Integration

Replace the placeholder \fbox{\parbox{...}} contents of the figure environment, keeping its caption and label:

\begin{figure}[tb]
\centering
\includegraphics[width=\columnwidth]{fig/label}
\caption{Caption text.}
\label{fig:label}
\end{figure}

What This Skill Does NOT Do

• Does not change prose content
• Does not add or remove figures beyond what the plan specifies
• Does not change figure labels or cross-references

Integration

• Receives from: writer skill (.tex files with figure placeholders)
• Reads: Data files referenced in placeholders, source code for data generation
• Maintains: plot_defaults.py, tikz_defaults.tex, and build_figures.py at the project root
• Produces: Per-figure directories with render.py or render.tex, outputs in each chapter's fig/ directory, updated .tex files
• Hands off to: formatter skill for final LaTeX polish