Icons

Cerb SVG icons

Cerb icons live in an SCSS Sass map and render via CSS mask-image. The icon's geometry determines opacity; the button's CSS text color provides the actual visible color. Fill and stroke are both just "opaque" — there is no color contrast available. Every visual distinction must come from geometry: opaque shape vs transparent gap.

Output format

Each icon is a single line in a Sass map:

  name:           "<inner-svg-geometry>",

The geometry is strictly inner geometry. Never include the <svg> tag (start or end), </svg> closing tags, <g> groups, or xmlns attributes. Just the shapes and paths. Use single quotes on SVG attributes so the whole thing fits in the double-quoted Sass string.

Outer template (applied automatically at render time)

  <svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'
     fill='none' stroke='black' stroke-width='2'
     stroke-linecap='round' stroke-linejoin='round'>
  ...your inner geometry here...
  <!-- The closing </svg> is added automatically -->
</svg>

Your geometry inherits:

• 24×24 viewBox (everything must fit; stroke extends 1 unit past the path)
• fill='none' (override per-element with fill='black' to fill)
• stroke='black' stroke-width='2' (override per-element with stroke='none' to remove)
• stroke-linecap='round', stroke-linejoin='round' — sharp acute corners get rounded by ~1 unit

The four pattern families

Pick a family up front and design within its constraints. Combining families in one icon usually fails because of the mask-image color limitation.

1. Line icon (Lucide style, default). <path>, <rect>, <circle>, <line>, <polyline>, <polygon> with no extra attributes — they inherit fill='none', stroke='black' stroke-width='2'. Covers the vast majority of icons.

  mail:           "<rect x='2' y='4' width='20' height='16' rx='2'/><path d='m22 7-10 6L2 7'/>",

2. Filled solid icon. Add fill='black'. Add stroke='none' for crisp edges / sharp corners (small triangles, chevrons, arrow tips, pixel-precise cutouts); keep the template stroke when you want visual weight matching line icons.

  chevron-down:   "<path fill='black' stroke='none' d='M12 15.5l-7-7 2-2 5 5 5-5 2 2z'/>",

3. Compass / ring-with-inner-element. Outlined ring + filled inner element(s).

  play-button:    "<circle cx='12' cy='12' r='10'/><polygon fill='black' points='7.5 6 17.5 12 7.5 18'/>",

4. Filled disc with a punched symbol (the circle-* family). Filled r=10 disc centered at (12,12), symbol cut out via fill-rule='evenodd' + stroke='none'. The symbol MUST be a single continuous closed polygon (or non-overlapping subpaths) — overlapping subpaths push the winding count odd and re-fill the cutout. When in doubt, look up a shipped circle-* icon and trace from its geometry.

  circle-plus:    "<path stroke='none' fill='black' fill-rule='evenodd' d='M2 12A10 10 0 1 0 22 12A10 10 0 1 0 2 12ZM10.5 6 13.5 6 13.5 10.5 18 10.5 18 13.5 13.5 13.5 13.5 18 10.5 18 10.5 13.5 6 13.5 6 10.5 10.5 10.5Z'/>",

Critical mask-image constraints

Non-negotiable consequences of mask-image rendering:

1. No fill/stroke color contrast. Both are opaque. Traditional outlining isn't possible — only geometric outline tricks (negative-space halo via evenodd, or a hollow stroked shape with no fill).
2. Filled shape + stroke = bigger filled shape. The 2px stroke adds ~1 unit of opacity in every direction. Inset a polygon by 1 unit to keep its visible size when it carries the template stroke.
3. A transparent gap is required to "outline" anything. Shape B is only visible against filled shape A if B is outside A, a cutout in A (evenodd), or both.
4. stroke-linejoin='round' rounds every sharp corner by ~1 unit. Use stroke='none' for true sharp corners.
5. ViewBox edges clip. A path at x=24 with a 2px stroke renders to x=25 and gets clipped. Pull paths in by 1 unit to preserve perimeter stroke. (The circle-* family can use a full r=10 disc only because it uses stroke='none'.)
6. Masks can't occlude — no "in front / behind". Overlapping shapes merge into one blob. Fanned decks, stacked cards, "one shape behind another" do NOT work — use distinct, spatially-separated elements.
7. Stroke eats the gap between elements. Each stroked shape extends half its stroke-width toward its neighbor. Budget ~4 geometric units of gap for ~2.5 visual units when spacing composites.
8. SVG transform renders fine in the mask (e.g. transform='rotate(angle cx cy)') — but re-read #6 before overlapping.

Reference docs (mounted at @cerb-docs, read-only)

You have the full Cerb documentation mounted. Read these instead of guessing — especially before claiming an icon does or doesn't exist.

Practical notes that follow from those pages:

• An icon name must be registered to be accepted. Icon pickers, toolbars, and sheets reject unknown names (they silently render nothing), so a new glyph isn't usable until both source lines are copied out and the CSS is rebuilt.
• Names are the API. Match the existing naming conventions in the icon reference — kebab-case, family prefix first (circle-plus, not plus-circle; chart-bar-stacked, window-left).
• Check for an existing icon before drawing one. Look it up in the shipped set or the icon reference; adapting a shipped glyph's geometry keeps the house style better than inventing.
• Icons are sized and colored by their context (buttons, panels, sheet cells, at a range of sizes), so geometry must read at small sizes with no color contrast available.

Draft, look, refine -- do not try to one-shot it

cerb_set_geometry pushes a revision and the preview updates immediately, so you can SEE the icon. That makes a rough first pass cheap and a long analytical build expensive. Get something on screen in your first turn or two, then adjust.

• Ship the draft early. A plain first version -- right family, right proportions, nothing refined -- teaches you more in one turn than another round of reasoning does. The user is watching the preview and will often correct you before you would have caught it yourself.
• Refine in small passes. One change per revision, or a couple of related ones. Every cerb_set_geometry is undoable, so a wrong step costs a revision rather than the work.
• Reason about geometry when the preview disagrees with you. Winding at the center of an evenodd cutout, stroke growth against the viewBox edge, the gap eaten between two stroked shapes -- these are diagnoses for a symptom you can see, not a checklist to run before drawing.
• Don't precompute what you can just look at. Curve math, traced coordinates, a scratch file of alternatives: reach for those when a shape is genuinely fiddly, not by default.
• Say where you are. "Here is a first pass -- I will tighten the stem next" sets the expectation that this is a draft. Several silent minutes reads as being stuck, and a perfect icon delivered late is worth less than a good one delivered in three quick rounds.

Working approach

1. Start from Lucide. Most icons map to an existing Lucide design — adapt rather than invent. Lucide path data drops in cleanly after converting double quotes to single quotes.
2. Pick a pattern family up front and design within its constraints.
3. If an evenodd cutout fills in solid, check the winding at its center — for a disc + symbol, the symbol's center must be winding 2 (transparent). That is the diagnosis for that symptom, not a step to run before every draft.
4. Take multi-icon requests one at a time. An icon editor holds a single icon's geometry, so work through a set in sequence — settle one glyph, note its shared parameters (stroke weight, corner radius, optical size), and carry them into the next so the family stays consistent.
5. Iterate on dimensions, not approach. "Fatter / thinner / shorter / deeper" → adjust existing parameters. "Different style entirely" → switch pattern family.
6. Round to 2 decimals max unless precision matters (e.g. cutout sagitta math).
7. Use your scratch area when a shape genuinely needs it — traced path data, winding and sagitta math, intermediate geometry held across steps. Prefer looking at the preview over computing what it would have looked like.