Imported from ThalesGroup/agilab (.codex/skills/svg-diagram-tuning/SKILL.md). Install upstream with npx skills add ThalesGroup/agilab --skill svg-diagram-tuning. Copyright stays with the author (BSD-3-Clause (see repo LICENSE)).

SVG Diagram Tuning

Overview

Use this skill to improve an existing SVG diagram without changing its meaning. Focus on readability first: text, spacing, arrows, and visual hierarchy.

When to use

• Text is too small or cropped
• Blocks overlap or feel cramped
• Arrow flow is unclear
• The figure needs to export better into DOCX or PDF

Workflow

1. Inspect the current structure and identify the source of crowding.
2. Fix geometry before increasing font sizes aggressively.
3. Sweep the whole semantic family before replying: if one card title, legend, callout, or arrow corridor is wrong, inspect the sibling elements of the same type and fix the full class of issue in one pass.
4. Rebalance titles, body text, padding, and connector anchors together rather than as isolated micro-fixes.
5. Rebalance line breaks across sibling cards together. If one block is rewrapped, inspect whether its peers need the same semantic treatment.
6. When a defect sits inside a local cluster such as source block + target block + connector, rebalance that whole sub-ensemble before changing the single line the user pointed at.
7. If the user asks to move only the arrow or only the block, obey that constraint literally. Do not compensate by silently moving the other element.
8. Preserve deliberate alignment contracts such as shared bottoms, shared centers, and column-internal spacing whenever you resize or move one member of the set.
9. Before editing, classify the requested change explicitly as one of:
   • arrow-only
   • block-only
   • text-only
   • local sub-ensemble rebalance Then edit only at that scope unless the user broadens it.
10. If the same local region attracts repeated complaints, stop doing line-by-line nudges and rebalance the whole region in one pass before replying again.
11. Keep one editable SVG as the source of truth.
12. Re-render only after the SVG itself is clean.

GitHub-first guardrails

Use these rules whenever the SVG will be viewed on GitHub, in a README, or in a blob/raw page:

• Treat text overflow as a hard failure. If any title, label, body line, or callout crosses a block edge in the target renderer, the SVG is not done.
• Treat repeated user complaints about one SVG as evidence that the previous pass was incomplete. Do a full regression sweep before responding again.
• Treat browser rendering as the target, not only one local SVG engine.
• Prefer conservative geometry over tight packing; GitHub/browser rendering is less forgiving than local slide or DOCX export.
• Use browser-safe font stacks first (Arial, Helvetica, sans-serif) unless the document already relies on a guaranteed embedded font.
• Keep decorative rules, dividers, and arrows out of text corridors. If a line comes near a label, move the line, not the label.
• Remove decorative rules entirely when they do not add structural meaning. Do not preserve a horizontal lane line just because it existed in an earlier revision.
• Keep a semantic vertical rhythm. Similar elements should use the same spacing pattern between title, kicker, body, note, and the next section break.
• Keep a semantic line-break rhythm too. Do not let one peer block use arbitrary manual wraps while its siblings use balanced semantic phrases.
• After moving or resizing blocks, recalculate arrow anchors from the final geometry. Do not leave connector coordinates inherited from an older layout.
• Declare markerUnits on every <marker> instead of relying on the SVG default. Prefer userSpaceOnUse for stable arrowhead size; retain explicit strokeWidth only when proportional scaling is intentional.
• For repeated connectors, keep arrow placement symmetric across the row or column so the figure reads as intentional rather than hand-adjusted.
• Center connectors on the geometry they are meant to describe. A vertical flow arrow should sit on the actual center axis of the card or lane, not on a stale inherited x.
• Treat lane rules and section dividers as a family too. They should share a deliberate start/end axis rather than drifting with each label width.
• Prefer widening a badge, pill, or summary card before wrapping what is really one short label or one atomic message. Use wrapping only when the content is genuinely paragraph-like.
• Treat one-line summary callouts as a special case. If a banner or flow summary was intentionally designed as one atomic sentence, do not let later grid tightening break it into two lines without an explicit semantic reason.
• For multiline card copy, make the block tall enough for the wrapped text first. Do not push a footer note, divider, or arrow closer just to preserve a fixed box height.
• If a block contains a title plus explanatory copy, reserve explicit top, middle, and bottom zones. Do not hand-place each text line independently without a repeatable vertical rhythm.
• If a block contains a title, one or more code pills, and explanatory copy, treat that as a stacked mixed-content card. Reserve explicit title, pill, body, and bottom-padding zones before tuning line breaks.
• Treat manual line breaks as part of the layout contract. Rewrap body and note copy by meaning, not by whatever happened to fit at one intermediate width.
• For a family of peer cards, choose one text structure on purpose: for example one centered title plus two balanced body lines, or one title plus body plus note. Do not mix one-line, two-line, and awkward broken phrases without semantic reason.
• Reserve a real vertical gutter between body text and footer notes. If the last body line visually touches the note below, the card height or note position is wrong even if the text does not literally overlap.
• Treat edge-touching as a defect class too. Adjacent cards, callouts, or side panels should keep a visible gutter; “not overlapping” is not a sufficient quality bar.
• Do not rely on implicit spacing between a numbered badge and the following title. Reserve explicit horizontal gap in the geometry.
• Do not keep long callouts on one line. Wrap them with tspan and increase the box size before shrinking text.
• Give legends and reading guides their own lane. Do not let a legend compete for the same vertical band as the last row of cards.
• If an error label or callout sits between a right-side card and a lower band, give that label its own corridor and rebalance both bands together. Do not wedge it into leftover space and hope the connector still reads cleanly.
• Keep card titles aligned by family. If most peer blocks use centered titles, do not leave one or two titles left-aligned without an explicit semantic reason.
• When compacting a panel that contains inner cards, reduce the panel height and then rebalance the inner cards as a family so the bottom gutter stays intentional.
• If a bottom band contains several related elements, prefer rebalancing that whole band instead of ratcheting one card up and down across many micro-fixes.
• When a right column or side column is moved, move its dependent badges and connectors by the same delta unless there is an explicit reason to break the column contract.
• When a user asks for repeated micro-moves on the same connector, keep a strict log of what was allowed to move so you do not accidentally drift nearby geometry.
• If a connector was intentionally converted to pure horizontal or pure vertical, do not reintroduce a diagonal unless the user asks for it or the semantic mapping fails.
• Attach area labels to the area they name. If a section header describes a pastel panel or grouped zone, place it inside that panel or flush with its edge so the target region is obvious at first glance.
• Attach connector labels to the connector they qualify. Labels like allocations should read as annotations of a nearby edge, not as loose text in empty space.
• Shorten labels like lane headers or section names before tightening letter spacing.
• When two renderers disagree, prefer the layout with more whitespace.

AGILAB Workflow

1. Edit the canonical SVG under ../thales_agilab/docs/source.
2. Sync the mirrored SVG under agilab/docs/source when the page is public.
3. Validate the edited SVG as XML before rebuilding docs.
4. Check the .rst page that references the figure so path changes do not break the published page.
5. Validate the rendered HTML page after publish instead of assuming the raw SVG source path will exist on GitHub Pages.

AGILAB Validation

• Parse the SVG locally with Python XML tooling if needed.
• Run the sibling svg-diagrams/scripts/check_svg_markers.py checker when the figure uses arrow markers; from the Codex mirror, use python3 .codex/skills/svg-diagrams/scripts/check_svg_markers.py path/to/figure.svg.
• Before replying, perform a semantic sweep of:
  • all card titles
  • all card bodies/notes
  • all legends/callouts
  • all arrows and arrowheads
  • section labels and lane headers
• Check body-to-note spacing inside every card, not only overflow at the card border.
• Check that line breaks are semantically balanced across sibling cards instead of looking random or width-driven.
• Check gutters between neighboring panels and side callouts, not only strict overlap.
• Check that arrows, lane rules, and labels still share the same axes after any grid shift. Geometry drift in connectors is a first-class defect.
• Check alignment contracts in the local region you touched: shared bottoms, shared centers, shared column offsets, and family spacing should still hold after the edit.
• Check that every area label still has an obvious target panel after any resize or repositioning.
• Check that edge labels still read as edge labels rather than free-floating text.
• Check whether each divider or lane rule is still justified. If it no longer adds meaning, remove it instead of polishing its alignment.
• Check that the final edit still matches the exact move contract requested by the user: for example move only the arrow, move only the block, or rebalance all.
• Re-render the SVG and visually inspect every text-bearing block for overflow, collisions, and clipped whitespace before pushing.
• If the same figure has already drawn a repeated complaint, inspect the rendered raster before replying; do not trust source coordinates alone.
• Re-check any badge, banner, or summary card that was previously one line after any global width or grid change. Do not assume it will survive a layout normalization.
• Re-check mixed-content cards for title-to-pill, pill-to-body, and body-to-bottom gutters after any resize.
• If the user pointed out one concrete defect, verify the same defect does not remain in sibling blocks before declaring the SVG fixed.
• Confirm the figure is referenced from the expected .rst page.
• For published docs, verify the embedding page such as architecture.html or agi-core-architecture.html; Sphinx may publish figure assets under _images/.
• For GitHub-facing SVGs, validate with at least two renderers when possible: rsvg-convert plus a browser-adjacent renderer such as Quick Look (qlmanage) or an actual browser screenshot workflow.
• If the user points to a GitHub blob/raw URL, treat that observed rendering issue as real even if a local renderer looks acceptable.

Priority order

• eliminate overflow and collisions
• fix the whole class of related defects, not just the line the user mentioned
• remove overlap
• clarify hierarchy
• widen crowded blocks
• increase text size
• simplify wording when layout alone is not enough
• add whitespace before trusting typography tweaks
• keep section labels and divider rules on one shared visual axis
• recompute connector geometry after every layout shift

Anti-patterns

• Do not reply after fixing only the one line the user cited if adjacent blocks still have the same defect class.
• Do not solve GitHub overflow by shrinking text first when geometry can be widened, rewrapped, or reflowed.
• Do not leave arbitrary manual wraps in a diagram after resizing a block. Revisit every edited phrase and choose deliberate semantic breaks.
• Do not place legends, guides, or notes into leftover whitespace without checking whether they visually collide with the main diagram bands.
• Do not keep decorative lane rules by inertia. If the section header already reads clearly without the rule, delete the rule.
• Do not “solve” a local layout complaint by alternating block moves and arrow moves without first deciding which element is actually allowed to change.
• Do not move one card in a bottom or side band without checking the alignment promise of the neighboring cards in that same band.
• Do not answer “done” after a sequence of micro-moves unless you have verified that the final state still respects the user's latest constraint.
• Do not leave area labels floating far from the panel they describe.
• Do not leave connector labels in ambiguous whitespace where they could refer to more than one relation.

References

• Read references/layout.md for the tuning checklist.