📐 TikZ figure style: layout, typography, and the pre-flight checklist

Status: standard, not mechanically checked. Written 2026-08-21. Updated 2026-10-05 (#1012: the house figure-style block, the type floor, the zoned spine). A future review-layer aid (FEATURE-ROADMAP.md's D2) may check some of the binary items below by compiling the figure; nothing here is gated today.

This is the TikZ-specific half of WRITING-STANDARDS.md §10's figure contract: that section owns the two-form (TikZ + ASCII) pair, the marker syntax, and originality. This document is what makes the TikZ half of the pair good, before it is kept.

Written for the figure-drawer skill, which survey-writer, tutorial-writer, thesis-chapter-writer and textbook-chapter-writer hand a figure to, and for anyone drawing one by hand. FIGURE-DRAWER.md says how the skill applies this document. deep-research does not draw §10 figures at all, so it has no reason to link here.

Not covered here: the two-form pair contract, the marker syntax and originality, all of which stay in WRITING-STANDARDS.md §10; the ASCII form's own 7-bit alphabet and column limit, also §10.

🏗 Commit to a layout metaphor before you draw

TikZ figures out of this pipeline sprawl when nothing asks for a plan before the first \node: boxes placed near other boxes, arrows added as needed. Committing to one metaphor before placing a node turns "place these nine things" into a constrained problem, which is the single change most likely to fix sprawl at its source. Each metaphor maps onto a TikZ idiom to use:

Metaphor	TikZ idiom
Pipeline	a chain, via the positioning library
Map	matrix
Layered stack	stacked fit layers
Control loop	cyclic edges with bend
Branching tree	tree
Hub-and-spoke network	a star
Zoned spine	fit plus backgrounds

(The first six are PaperBanana's planner supplement, read and not copied; INSPIRATION.md carries the credit.)

The zoned spine is one left-to-right path that carries the argument, with each zone card a tinted region behind a group of members and its title outside the card's top-left corner. Reach for it when the figure has one storyline and several parallel commentaries on points along it. The card is a fit node drawn on background layer, so it never paints over a member and re-wording a member widens the card instead of escaping it. If nothing comments on the path, it is a pipeline.

There is a starting file for every row of that table, in assets/tikz/. One per metaphor, named for it, each compiling on its own and each reporting no binary finding from python -m chitragupta.review figure. Copy the one whose metaphor fits and re-label it; the choice above exists to hand you a file rather than a blank tikzpicture. assets/ is copied into a project by chitragupta init, so they are already beside a scaffolded draft and there is nothing to download. assets/tikz/README.md says what each one is for.

Every scaffold places its nodes relative to one another, and none of them places a node at a coordinate in millimetres. That is the property to keep when you edit one. A figure laid out in hand-computed absolute millimetres cannot express "do not collide": re-wording one label, or setting the figure at a different type size, re-opens every adjacency in the picture at once and each of them has to be re-checked by eye. Relative placement and fit layers make most of those collisions impossible, not merely detectable.

The millimetre rule governs composition, not objects. Every node in a figure is placed relative to another node, and that does not change. Inside a pic definition, explicit millimetre coordinates are correct and expected: a pic is a fixed object drawn once, whose internal geometry does not reflow when a sibling's label changes. The boundary is the pic, not the authoring method: a shape generated by a derivation gets the same carve-out as a hand-drawn one. Hand-placing a whole figure is still the defect the rule exists to prevent.

Name every node you draw, in whichever idiom. review figure measures a node's geometry only where the source gives it an explicit (name), so a picture that names nothing reports no overlap and no protrusion because nothing was measurable. That output reads exactly like a clean figure, but the figure was never checked. Both spellings count: \node (a) and child { node (a) ... }. That includes the well a pic is drawn into: draw a pic only at a named cgwell (see House shapes).

The tree idiom has one cost that is not visible in the output: child draws its edges internally rather than as \draw statements, so the edge list review figure reports for such a figure is empty rather than short. Confirm a tree's wiring from the source's own nesting.

Every idiom in that table needs a \usetikzlibrary line, and the figure file carries it at the top, above the tikzpicture:

\usetikzlibrary{positioning}
\begin{tikzpicture}[thick,x=1mm,y=1mm]

The renderer collects those lines and loads the union in the preamble (chitragupta/render_output/_tikz_libraries.py, #781), so by the time your figure is \input the library is already there and your own line is a no-op. Keep the line anyway: it is what lets the same file compile in the two documents this pipeline does not write, which are thesis-chapter-writer's fragment inside a user's own thesis and the minimal probe document WRITING-STANDARDS.md §10 tells you to build around one figure. Without any load at all, a picture that reaches for below=4mm of store does not fall back; it fails the whole render with a message that names neither the library nor the figure:

! Package PGF Math Error: Unknown operator `o' or `of' (in '4mm of a').

Write nothing else about loading. No clearing of \tikz@library@<name>@loaded, no saving or restoring of \tikz@node@reset@hook, no \ifdefined guard around the load. Those workarounds exist in older figure files and they are the bug, not the fix. \usetikzlibrary is legal in the document body, but a figure file is \input inside a figure float, and a float is a group: the load defines the library's macros locally while setting the loaded flag globally, so the next float skips the load and finds no macros. Clearing the flag to force a reload is worse: positioning appends its placement transform to a global hook on every load, so the Nth figure shifts every node N times. Measured on a three-float document: 71.26pt, then 128.17pt, then 185.07pt, with pdflatex exiting 0 and nothing but Overfull \hbox in the log. That is how figures that fit in their single-chapter PDF spilled off the page of this project's own assembled book. python -m chitragupta.review figure reports one as loads-library-by-hand.

Before you reach for a library:

• A missing name takes the whole call down. \usetikzlibrary{} fails fatally on the comma list rather than skipping the name it cannot resolve, so one typo reads exactly like several missing packages. Probe a library by compiling a two-line document that loads it, not with kpsewhich tikzlibrary<name>.code.tex, which only sees tikz-layer files and so misses every pgf-layer library (arrows.meta is pgflibraryarrows.meta.code.tex, and resolves fine).
• shapes.geometric, not shapes.geometry. The second is not a PGF library at all.

texlive-pictures, which scripts/install_full_pipeline.sh already installs, ships all of these; there is no extra package to add for any of them.

🔠 Panels in one figure, and the letters they need

A figure that shows the same thing under two or three conditions is one figure with panels, not two or three figures. However many panels it has, it stays one figure, one figure: marker and one .tex/.txt pair. One marker per panel would give you separate floats with separate numbers, which is a row of figures rather than a panelled one. Nothing here is specific to two: letter as far as the figure goes.

Every panel carries a label node reading (<letter>) <short title>, and the letter is the panel's position in reading order: (a) for the first panel, (b) for the second, (c) for the third, and on through the alphabet. Reading order is left to right, then top to bottom, so it is the panel's place in the picture that decides its letter, not the order you happened to draw the nodes in: move a panel and its letter moves with the position, not with the panel. Draw the label as an ordinary node under the panel it names; a panel with a bold title and no letter cannot be pointed at from the prose, which is what the letter is for. Prose then refers to Figure~\ref{fig:x}(b) for the second panel, with the letter typed, since these letters are drawn rather than counted by LaTeX.

Put the same letters in the ASCII twin. Every format except tex/pdf (md, html and docx alike) renders the .txt and never sees the picture, so for three of the five formats the ASCII form is the only place the sub-captions exist. Letter it by taking the four columns from the gap to the left of each title rather than by inserting them, or every title after the first slides off the panel it labels; the letters then overhang their panels by four columns, which is the intended look and keeps §10's ~70-column cap intact.

When a row stops fitting, wrap into another row; never scale the picture. Three panels of about 48mm each overflow an ordinary text block by 71.8pt, and pdflatex only warns: Overfull \hbox, in a log nobody reads, with the figure in the margin. Four of the same panels as a 2x2 grid fit with no warning at all. Reaching for \resizebox or scale= instead would shrink the node text below the document's own size, which "Type and line weight" below forbids for exactly this reason.

Where the figure is captioned, write the caption in the draft, not in the figure file. Issue 411 moved that half out of TikZ style's reach: a Markdown draft writes its caption directly below the figure: marker (WRITING-STANDARDS.md §10), and the renderer, not the figure file, wraps the marker in a figure float with \caption/\label, so LaTeX's own counter numbers it. The figure file itself stays a bare tikzpicture fragment, same shape as assets/tikz/'s own scaffolds, and copying one no longer includes wrapping it in a float by hand.

thesis-chapter-writer's .tex fragment keeps the older shape, because it carries no marker for the renderer to wrap: it hand-authors its own \begin{figure}...\caption{}...\label{fig:<id>}...\end{figure} around the inline \input. The one change there too: never write \renewcommand{\thefigure}{N.M}. The figure counter it would override is exactly what makes \ref agree with the consuming thesis's own numbering; a hand-typed number is wrong the moment that thesis renumbers a chapter, which is the defect issue 411 exists to remove.

Do not reach for subcaption, subfig or subfigure. The package is installed on a typical TeX stack, so this is a choice rather than a limit. \usetikzlibrary is legal in the document body and \usepackage is not (! LaTeX Error: Can be used only in preamble.), so a figure file can load its own TikZ library but never its own package, and the preamble that would have to load it is not always ours. thesis-chapter-writer's fragment is \input into the user's own thesis, whose preamble we never see, so a figure needing subcaption compiles here and fails there. Drawn letters work in every genre and change no preamble. The whole cost is \subref and automatic "Figure 1a" numbering, which is one typed letter per reference.

Record the convention, don't re-decide it. Which letters a venue wants ((a), (i), A, or titles alone) is a house-style decision in WRITING-STANDARDS.md §8's sense, and belongs in the dossier's scope.md beside the dialect. draft-reviser reads that file before every edit; a convention agreed in chat is gone by the next session.

A three-panel figure, relative placement throughout, verified on this host: it compiles, every node it names comes back measured, and python -m chitragupta.review figure reports nothing:

\usetikzlibrary{positioning,fit}
\begin{figure}
\centering
\begin{tikzpicture}[thick,
                    box/.style={draw,align=center,
                                minimum width=17mm,minimum height=8mm}]
  \node[box] (senseA) {sensor};
  \node[box,below=6mm of senseA] (storeA) {store};
  \draw[->] (senseA) -- (storeA);
  \node[fit=(senseA)(storeA),draw=none] (panelA) {};
  \node[below=2mm of panelA] (labelA) {(a) polled};

  \node[box,right=12mm of senseA] (senseB) {sensor};
  \node[box,below=6mm of senseB] (storeB) {store};
  \draw[->] (senseB) -- (storeB);
  \node[fit=(senseB)(storeB),draw=none] (panelB) {};
  \node[below=2mm of panelB] (labelB) {(b) pushed};

  \node[box,right=12mm of senseB] (senseC) {sensor};
  \node[box,below=6mm of senseC] (storeC) {store};
  \draw[->] (senseC) -- (storeC);
  \node[fit=(senseC)(storeC),draw=none] (panelC) {};
  \node[below=2mm of panelC] (labelC) {(c) buffered};
\end{tikzpicture}
\caption{One reading path under three delivery modes.}
\label{fig:delivery-modes}
\end{figure}

tests/test_tikz_subcaptions.py reads that example out of this file and compiles it, so it cannot drift into something that no longer works. The empty fit nodes are what give each panel an extent to hang its label under; they are grouping boxes, which review figure excludes from its overlap check by design, and any other way of finding the same point is equally fine. What the rule asks for is the label and its letter.

✅ Check the drawn figure against this list

Concrete defects, not taste:

• Occlusion and overlap: no two nodes' boxes intersect.
• A fill erases everything under it, not just the line you aimed it at. Filling a label white and drawing it last is the standard way to make a line break at the text instead of striking through it, and it works, but the fill is a rectangle the height of the whole node and the width of the whole label, and it paints out every arrowhead, border and rule that rectangle happens to cover. A one-line label 139mm wide, filled to interrupt one vertical arrow at x=24, also deleted an arrowhead and the top edge of a box at x=70: the edge rendered as a stub going nowhere and the box as three sides. Ask what else is in the band before reaching for fill=white, and note that shrinking the band rarely rescues it: inner ysep=0pt bought 0.06mm in that case, and breaking the label over two lines makes the band taller, not narrower.
• One arrow is one \draw. Two colinear segments that meet, each carrying ->, render as an arrowhead where they join as well as at the end, a second head pointing at nothing in the middle of the line. If a line needs to be built in pieces, put the -> on the last piece only. This one is mechanically checked, where the pieces meet at a bare coordinate: chaining head-to-tail through a named node is how a pipeline is normally drawn and is not a defect, because TikZ clips each path at the node's boundary so the head points at the node rather than at empty space.
• Chaotic routing: arrows should not cross unnecessarily or form spaghetti loops. Left off the mechanical checks that may eventually exist; a bad approximation of "does this route look chaotic" would be worse than not checking it at all, so this one stays a human judgement.
• Illegible or inconsistent type, and low contrast: one font size per role, held consistent across every node in the figure. See "Type and line weight" below for what size that should be.
• Inefficient non-rectangular composition: LaTeX treats a figure as a rectangular box, so anything protruding above the main block forces the surrounding text to wrap around the highest point, wasting vertical space. Keep the picture's bounding box close to the union of its node boxes.
• Conciseness: a node whose text runs past 15 words is too long for a box; cut it or split the node. Shrinking the font to fit more words in is not a fix (see "Type and line weight" below).
• The figure's main point resting on colour alone. Colour is house-standard here and carries meaning freely (see "The house palette" below). What it may not do is carry the whole point on its own, because two readers get none of it: the ASCII twin is 7-bit, and md, docx and html render only that form; and a black-and-white print greyscales the TikZ form, where cgFlow and cgAlt land at similar lightness. Position, arrow direction and node labels should still deliver the argument; colour should make it fast. The test is quick: read the .txt twin and ask whether the point still arrives. A secondary distinction living only in colour is fine and expected.
• Literal copying: a box-ified copy-paste of prose, with no visual abstraction, is not a figure. This is WRITING-STANDARDS.md §10's originality rule applied to figures, and it matters more than it looks: a figure can launder borrowed wording past every detector in PLAGIARISM.md, because a citekey is already kept out of figure files and the gate does not follow \input.

🔤 Type and line weight

Two conventions, both about a figure looking like a native part of the document rather than something pasted in:

• The smallest type in a figure equals the document's body size. That is a floor, not a target: nothing in a picture may be set smaller than the paragraph beside it, and a figure is free to go up from there. The house ramp is two steps: \normalsize for every gloss, edge tag, note, legend entry and badge, and \large\bfseries for node names and zone titles. Set the floor explicitly as a picture option (\begin{tikzpicture}[cg] does it), rather than inheriting it, so a picture that lands inside a float, a table cell or a \small group does not quietly drop below it.

Shrinking type is never the fix for a box with too many words in it: that is the conciseness defect, and the fixes are fewer words or a wider box. Going the other way costs nothing: a larger name gives the figure a hierarchy the flat version has to spell out in the caption. Two exceptions, both automatic and both correct: a mathematical subscript or superscript set by TeX's own script style, and the \caption, which is the document's, not the figure's. tests/test_tikz_scaffolds.py holds every file in assets/tikz/ to this by reading each glyph's printed size back out of the compiled PDF, not by reading the source, because the size that breaks it usually arrives from somewhere the figure file cannot see. - Lines are distinctly thicker than TikZ's own default. \pgflinewidth defaults to 0.4pt, TikZ's thin key (verified with \typeout{\the\pgflinewidth} on this host). Draw node borders and arrows at thick (0.8pt, double the default, same probe) instead; a figure left at the bare default reads as faint next to a document's normal text weight. Set it as a picture option, not a restated style: \begin{tikzpicture}[thick], which the house block's [cg] already includes. Do not reach for \tikzset{every node/.style={thick}} to do this: /.style= replaces whatever every node already held, so a figure with its own node style (draw, circle, a fill colour) silently loses all of it the moment this line runs after that one. Verified on this host: a circular node's bounding box, forced through exactly that sequence, came out identical to a plain undecorated node's; the circle and the border were both gone. \begin{tikzpicture}[thick] cannot clobber anything, because it never touches every node at all.

🎨 The house palette

Figures here are in colour, and they use one palette. Five named colours with a role each, and four more that a zoned figure needs. A figure that invents its own hues reads as imported from somewhere else, which a house palette exists to prevent.

\definecolor{cgInk}{HTML}{1A1A1A}     % borders, labels, default strokes
\definecolor{cgFlow}{HTML}{0072B2}    % the primary path through the figure
\definecolor{cgAccent}{HTML}{D55E00}  % the one thing the figure is about
\definecolor{cgAlt}{HTML}{009E73}     % a second class of node or edge
\definecolor{cgAux}{HTML}{56B4E9}     % auxiliary, secondary, "also happens"
\definecolor{cgWarm}{HTML}{E69F00}    % a third zone
\definecolor{cgRose}{HTML}{CC79A7}    % a fourth zone
\definecolor{cgPaper}{HTML}{FAFAF8}   % card ground, one step off white
\definecolor{cgMute}{HTML}{8A8A8A}    % muted ink, as a name

(Inside assets/tikz/cg-figstyle.tex each of these lines ends its } with a %, so the block sets no stray space; see "The house figure style" below.)

cgWarm and cgRose are one hue per zone. They are Okabe-Ito's remaining qualitative members, so the extension is the same palette rather than a second one: a zoned figure needs one hue per zone, and five roles do not stretch to six zones without reusing one, which reads as a claim the figure is not making. cgMute is a named grey because the house styles take a colour as an argument and paste it into a tint (fill=#1!11): cgInk!55 passed in becomes cgInk!55!11, which xcolor rejects with "Undefined color". Every role that needs muted ink therefore needs a name. cgPaper is the card ground, one step off white for the same reason cgInk is not black.

The values are Okabe-Ito's colourblind-safe qualitative set (Okabe & Ito, 2008), the usual choice for this purpose, and it costs nothing to adopt. cgInk is a near-black rather than black, because a pure black border next to body text set in the same ink reads heavier than the text does.

Each colour has a role. Use cgAccent for one thing per figure: if two things are accented, neither is. cgFlow carries the spine; cgAux is for what happens off to the side, usually dashed as well as coloured. cgAlt exists so a figure with two node classes does not have to reach outside the palette.

Tints for fills, the named colour for strokes. fill=cgFlow!8 is a zone wash that text still reads through; fill=cgFlow is a block of solid blue with your label lost inside it. Between 8 and 15 is the usable band, and draw= always takes the colour undiluted.

One contrast caveat: cgAux is light. It is fine as a fill and as a thick stroke, and not usable for label text on white. cgInk, cgFlow and cgAccent are all safe for text.

📎 The palette travels inside the figure

The palette travels as part of the house block (next section), which every figure carries whole. Not in a shared file the figure \inputs, and not in a preamble: the renderer injects \usepackage{tikz} and nothing else, and thesis-chapter-writer's fragment is \input directly into the user's own thesis, which has never heard of this project. A figure that depends on a colour defined elsewhere compiles here and fails there, which is the worst of the two orders to fail in.

This is the same discipline the \usetikzlibrary line already follows, for the same reason, and it means the definitions are duplicated across figures on purpose. The seven scaffolds in assets/tikz/ all carry the block, so copying one gets it for free.

🧱 The house figure style

assets/tikz/cg-figstyle.tex is the palette grown into the rest of the vocabulary a figure needs to look drawn rather than assembled, so a figure stops re-deciding corner radius, rule weight, tint depth, arrowhead and label structure from nothing each time:

Group	Keys
Palette	the nine colours above
Picture default	cg: thick, round caps and joins, font=\normalsize, ink colour
Node roles	cgbox cgalt cgaux cgwarm cgrose cgplain cgkey cgnone cgopt
Shadow	cgsoft (on in every filled role) and cgflat (cancels it; cgnone and cgopt use it)
Zone card	cgzone=<colour> and \cgzonelabel{<fit node>}{<colour>}{<text>}
Edges	cgedge cgweak cgback cglead=<colour>
Annotation	cgtag (a word on an arrow, on its own ground), cgnote
Badges	cgbadge=<colour> and \cgstep{<n>}{<node>}{<colour>}
Legend	cgswatch=<colour>, \cglegenditem{...}
Label ramp	\cglab{<name>}{<gloss>}
Icon well	cgwell: a named, invisible, fixed-size node a pic is drawn into

It also defines five house pics, each drawn into a cgwell; see House shapes.

The block needs one library line, at the top of the figure with the picture's own:

\usetikzlibrary{arrows.meta,positioning,fit,backgrounds,calc,shadows.blur}

All six ship with texlive-pictures. shadows.blur comes from the pgf-blur package but is reached by \usetikzlibrary, not \usepackage, which is what lets the soft shadow travel into a thesis preamble this project never sees: a figure file cannot load a package.

The block travels between its two marker comments, and python -m chitragupta figure sync keeps it current. The command stamps the block into a figure file that lacks one, above its first \usetikzlibrary or tikzpicture line, and replaces a block from an older release with the installed one. Everything outside the markers stays byte for byte as it was. With no paths it walks every content/drafts/**/figures/*.tex; --check writes nothing and exits 1 if any file is not current. chitragupta draft render reports a stale or missing block as a [figure] warning naming the command, and renders anyway: it never rewrites a figure itself.

Never edit inside the markers. A style one figure needs goes in that picture's own options, or in a \tikzset below the end marker. figure sync recognises every block this project has released by its digest, so a region that matches none of them was edited by hand. It leaves that region alone and prints the diff against the house block, for a person to move the edit out. A style that three or more figures need is a pull request against cg-figstyle.tex, not a local override.

Changing the block means a new version. Bump the v<N> in its first line and add that version's digest to assets/tikz/cg-figstyle.versions.toml, never editing an existing line there. tests/test_figure_block.py fails when the block and the register disagree, so an edit without a version bump cannot reach main. Then run python -m chitragupta figure sync assets/tikz/*.tex assets/tikz/exemplars/*.tex to refresh every scaffold and exemplar, which tests/test_tikz_scaffolds.py still checks byte for byte.

Repeating it once per figure is safe, by the same argument #781 makes for \usetikzlibrary. \tikzset re-defines the same keys to the same values, and every macro is \providecommand, so N figures in one document carrying N copies cost N definitions and change nothing. No global hook is appended to and no loaded flag is set. The one construct without this property is \tikzset{every node/.style=...} (see "Type and line weight" above), and the block touches every node only through .append style inside the cg picture option, scoped to one picture.

🧰 House shapes, and the well they sit in

The block defines five pics: small conventional shapes drawn in the house line weight.

pic	Stands for	Twin says
cgstore	a drum: any persistent store, such as the ledger, the vector store or a forward index	[ledger]
cgdocs	a stack of pages: a document, or a set of them	[PDFs]
cgfunnel	any place the set gets smaller: a cap, a top-k, a filter	[cap 3 per source]
cgchip	anything that computes: a model, an encoder, a reranker	[bi-encoder]
cgshield	the one blocking check, at most once per figure, if at all	[gate]

Each passes the ASCII twin's test by construction. It sits directly above a node whose label already says the same thing, so the shape is a rendering choice and never a proposition, and the twin loses nothing by dropping it.

Draw every pic into a well. A pic is a path, not a node, so it has no name, and two things break quietly without one. review figure measures only named nodes, so an icon colliding with a label reports clean. And a zone card can fit only named nodes, so an icon placed above a node pokes through the top of its own zone. cgwell is an invisible, fixed-size (10mm), named node that the pic is drawn into:

\node[cgwell, above=2.5mm of sync] (isync) {};
\pic[cg pic colour=cgFlow] at (isync) {cgstore};

Every house pic fits inside its well, and tests/test_tikz_scaffolds.py measures that, so an edit that makes one overflow fails there. pipeline.tex shows the idiom.

Colour. cg pic colour takes a palette name and applies to that one \pic. Give it the hue of the zone the shape sits in: the same drum is green in the lexical zone and blue in the dense route.

This is not an icon set, and it should not become one by accretion. A shape is added only when a metaphor in the layout table wants it, and only when the node's own label already carries the proposition. Five is the ceiling for now. A sixth needs the same argument made again, in writing, in its pull request, and a row in the table above; tests/test_tikz_scaffolds.py fails if the block and the table name different shapes.

🖨 What the other two forms do with it

Two readers receive no colour at all, and this is accepted rather than designed around:

• The ASCII twin is 7-bit, so md, docx and html get none of it. The twin still has to work as a figure (that is WRITING-STANDARDS.md §10's two-form contract, and it is unchanged), but it is not required to reproduce the colour form's every distinction.
• A black-and-white print greyscales the TikZ form, where cgFlow and cgAlt land at similar lightness.

So the practical rule is weaker than "never encode meaning in colour" and stronger than nothing: colour may carry meaning, and should not be the only thing carrying the figure's main point. Keep the spine legible through position and arrow direction, which every layout metaphor above already gives you, and let colour do the work of making the figure quick to read rather than possible to read.

📏 Draw for the width it will be printed at

The six layout metaphors have no width dimension, and a figure drawn without one in mind is a figure whose type size is decided by accident. A single-column figure in a two-column paper sets at roughly half a page width; the same picture dropped into a thesis sets at nearly double that. Nothing in the picture changes, but the type does, because scale= and the consuming document's own width between them decide the final physical size of every label.

So settle the target width before choosing a metaphor: a hub-and-spoke needs horizontal room a single column does not have, and is the wrong metaphor there however well it fits the content. A layered stack degrades gracefully to a narrow column; a wide map does not.

Never wrap a figure in \resizebox or \scalebox, and never set scale= on the picture. A picture drawn at its natural size and then scaled to fit prints its type at whatever the scale factor happens to be, so the floor in "Type and line weight" becomes a number nobody chose. Settle the target width first, lay the figure out to it, and \input it bare. If it does not fit, change the layout (wrap a row, cut a gloss, drop a stage), never the scale. The row count following from the type size is the right direction for that decision to run.

This is the rule that actually gets broken, because the scale is invisible in the figure file: it lives in the draft that \inputs it. Measured on six hand-written figures in one acmart sigconf paper (9pt body), each wrapped in \resizebox{\textwidth}{!}{...}:

Figure	Natural width	Scale applied	Smallest type printed at
architecture	462.8pt	1.094	6.6pt
rag-stages	548.9pt	0.922	5.5pt
retrieval	519.5pt	0.975	5.9pt
coauthoring	520.8pt	0.972	5.8pt
prompt	425.6pt	1.118	6.7pt
revision	420.6pt	1.180	7.1pt

Six figures, six effective type sizes, none of them chosen. Laid out again to fit 506.3pt unscaled, every label printed at 8.97pt or above. Expect the floor to change layouts, not just sizes: rag-stages went from two rows to three, and retrieval's dense route wrapped. Three of those redrawn figures ship as assets/tikz/exemplars/.

The renderer is already clean here: render_output/_figure_captions.py emits a bare \begin{figure} around the marker with no scale knob, so a pipeline-rendered figure is drawn at natural size. The defect is what a hand-written document does, which is exactly thesis-chapter-writer's case: its fragment is \input into a thesis this project never sees. The seven scaffolds are each laid out to the article class's 345pt text width, and a test compiles each one there and fails on an Overfull \hbox.

No venue table is bundled here, deliberately. Column widths are per-publisher, differ between initial and revised submission, and go stale; a table checked into this repository would be read as current long after it stopped being. If you keep one, keep it the way a maintained one is kept: a date it was accessed, a source URL per entry, and the standing caveat that a passing check is not compliance. Re-read the publisher's live page before you submit.

🧿 Rules that are not universal

Figure guidance is mostly written for raster images, and several rules that sound authoritative do not transfer to a TikZ picture at all. Named here so nobody spends an afternoon satisfying one:

• "Line art must be 600 or 1000 dpi." A TikZ figure is vector and has no DPI. There is nothing to set and nothing to check. The requirement that does transfer is physical width, above.
• "Convert everything to CMYK / everything to RGB." A colour-space question about exported raster assets. It reaches a \input-ed TikZ picture only through whatever the consuming document does at export, which this pipeline does not control and should not pretend to.
• "Make the figure bigger so the text is readable." Backwards. Enlarging the picture enlarges the type and everything else, so it overflows the column and gets scaled back down. Type size at final scale is the quantity that matters, and \footnotesize inside a picture that is then scaled to 0.8 is the real defect.
• "Pick a colourblind-safe palette and accessibility is handled." Necessary, and not the end of it. The house palette is already Okabe-Ito, so the hue question is settled and you should not be re-deciding it per figure. What a safe palette does not address is the two readers who receive no colour at all (the ASCII twin's audience and anyone printing in black and white), which is a redundancy question rather than a palette one.
• "A vector figure is resolution-independent, so size does not matter." True of fidelity, false of legibility, and the second is what a reader notices.

🚫 Nothing here is a gate

This is a checklist an author checks a figure against, not something enforced mechanically today.

python -m chitragupta.review figure reaches the part of it that geometry can decide, and it is a user-driven aid: a person runs it over a finished figure, it exits 0 whatever it finds, and nothing downstream blocks on it. Three consequences follow, and they are the ones authors get wrong:

• It measures; it never places. TikZ computes the layout, and the aid compiles the figure and reads back where things landed. So the fix for a finding is to change what you asked TikZ for (a sibling distance, a row sep, a different library), and never to nudge a coordinate until the number moves. assets/tikz/ is the starting point for that, and none of its seven scaffolds places a node at a coordinate.
• Its thresholds are the checker's, not this document's. "An empty band worth more than a third of the height" is a number chosen so ordinary layouts pass; it is not a rule from the list above. It does shape what passes (a two-row diagram spread out generously trips it with nothing wrong), so when a finding and your own eyes disagree, the eyes win and the figure stays.
• A clean report is not a checked figure, and the report now says which it is. The geometry checks measure only nodes the source names, so a picture that names none has nothing to measure. That used to print as No layout findings, identical to a figure where every check ran and found nothing; it now prints as its own finding, with the declared names that did not come back listed beside it. Name the nodes you draw, in whichever idiom; \node (a) and child { node (a) ... } both count.

REVIEW.md has the aid among the other nine; CLI.md has its flags and the full statement of the boundary.