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0058. Lines without heads, free lines, sketched strokes and vertical text alignment

Status: accepted (lines-and-text-alignment change, 24 October 2026). Extends decisions 0003, 0007, 0012, 0013, 0018 and 0043. Pen strokes, which the sketch passes leave as drawn, are decision 0064. The text sizes and weights leave the free-only properties, and thirteen more families are bundled, in decision 0067.

Context

Section titled “Context”

The owner asked for three things on 2026-10-23, and each had one cause in the language or the drawing.

  • A relation could not be a plain line. The lexer made -> and --> arrows and -digit a number, and any other run starting with - was an unknown token, so a -- b was syntax.unexpected-character. The only line between two boxes was a named relation with style x { arrowhead none }, which is what the Mermaid and PlantUML importers wrote for every open link.
  • Nothing could be a line that joins no element: the free kinds were box, text, icon, image and group, every relation joins two elements and every route names a relation, so a divider, a bracket or an underline on a slide had no statement.
  • Nothing looked hand-drawn, which whiteboard tools offer for early thinking, and the renderer had no dependency to draw it with.
  • Text in a free box could move across (textAlign, free-only by decision 0043) but not down: its vertical place was one point per shape.

Decision

Section titled “Decision”
  • Two line tokens. -- (a solid line) and --- (a dashed line) join ->, -->, <-> and <-->: one dash more is dashed, and the lines drop the head glyph. The lexer takes the longest match (---, -->, --, ->, then a number), so ---> is --- followed by an unexpected >, and the hint names the six tokens. Flow and free diagrams take the six; sequence diagrams take the four arrows (a message is a call or a reply) and C4 views -> and --> (their relations come from the model), refusing the others with prop.invalid-value on the token, as views refused <-> already.
  • A heads fact. A relation records heads, end, both or none, from one table of the schema that also gives its line; twoWay stays and is heads === "both", and arrowToken(line, heads) gives the token back to the importers, the edits and the C4 model. The heads are only defaults: the end head is arrowhead, else none for a line, else the theme’s, and the start head is arrowtail, else the end’s for a two-way relation, so a -- b with arrowhead circle still ends in a circle. The model JSON gains heads after twoWay; the version stays 0.1.
  • The importers write the tokens. Mermaid --- and === (with width 3) become --, -.- becomes ---, architecture -- edges become named -- lines with their routes, and block-beta open links become lines; PlantUML headless arrows become -- (--- when dotted), a left UML head with no right head (*--) becomes -- with arrowtail, and note links ---. No sheet writes arrowhead none for a line any more, and relations that were named only for that style are anonymous.
  • A free line object. line <id> ["Label"] from (x, y) to (x, y) [via [(x, y), ...]] [{ ... }] is a declaration of free diagrams. The label is the second argument, empty by default; the points are in the parent’s interior coordinates, as place is, so a line in a group moves with it. A line takes no place, size or rotation, takes the styles of a relation (stroke, line, width, heads, routing, corners, and the pill’s colours and icon) and refuses those of a box; label <id> at … moves its pill, and rule line { } styles every line. The model JSON gives every element line after shape, null but on lines.
  • Lines are drawn as connectors. The layout turns a line into a connector plan beside the relations’: its written points, polyline by default (and for auto, with no box to anchor to), orthogonal with an elbow between points that differ on both axes, bezier through them, corners, heads none by default and cut as a relation’s, a label pill at 50 %. It takes no lanes, detours or gaps under titles. Its scene group has role element with both a track and bounds, so it is painted in source order like any object and every effect (flow, dash, pulse, trace) runs along it: planMotion animates any group with a track as a connector. Coinciding points draw a dot and report layout.degenerate-line (warning).
  • Lines on the canvas. The arrow button’s menu lists the six kinds and R cycles them. On a free diagram the armed relation tool dragged on empty canvas draws a line: a ghost with the kind’s dashes and heads, snapped, Shift for 45°, Escape cancels; the release writes the line inside the group under the press and the kind’s styles in one edit (line dashed, and the theme’s arrowhead token for the heads, so an editorial sheet gets open). A press on an element keeps the two-click relation sequence. A selected line shows its outline, end, bend and midpoint handles; drags and nudges post setLinePoints, which rewrites the tuples with minimal edits and inserts or removes via.
  • sketch is a theme token painted by the renderer. sketch none|light|rough; the built-in themes write none, and two new built-in themes, sketch.light and sketch.dark, are the technical pair with sketch light and corners rounded, eight in all; sketch is a reserved import name. renderSvg draws every stroked rect, path and polyline of the element, relation, label, frame, lifeline and event groups, heads and pills included, as the fill alone plus two stroke-only passes: the outline (a rect turned into four sides with quarter arcs) sampled every 16 px (light) or 12 px (rough), each sample moved along the normal by at most 0.6 px or 1.4 px from a mulberry32 sequence seeded by a hash of the group’s id and the pass. Width, dash, dash offset, class, opacity and transform are copied to both passes. Text, images, icons, the mark, gradients and patterns are untouched, and the layout’s scene, tracks, bounds, hit tests and canvas overlays stay clean. The theme panel shows sketch as a row of pictures.
  • Patrick Hand for the sketch text. The owner approved the download on 2026-10-24, and @fontsource/patrick-hand 5.3.0 (OFL-1.1) is the fourth bundled family: one weight (400) in the Latin, Latin Extended and Vietnamese subsets, measured, outlined and embedded like Cascadia Mono (no complete file). The sketch themes name "Patrick Hand", "Inter", …, so the characters it lacks (Greek, Cyrillic) are measured with Inter, outlined with it, and left to the viewer’s fallback when embedded, and no sketch picture carries layout.unmeasured-font. Every weight takes the one file; the embedded @font-face rule declares font-weight:400 700 (EmbeddableFace.weightTo) so a browser draws a bold label with the same outlines as the layout measured and the outlined export draws, not a synthesized bold; a face that several weights ask for is embedded once, limited to the characters of them all. The licence inventory gains its row.
  • verticalAlign within the shape’s text band. top, middle (default) or bottom, a free style property beside textAlign, refused in flow diagrams as decision 0043 refuses the text properties. The text block keeps its height; top searches the shape’s text band from its top edge plus padding for the first row band whose inscribed span holds the block, bottom from the bottom edge, and the block moves back towards the middle when no band holds it. The band is each shape’s: the box, the inside of a curve, between a cylinder’s rims, above a document’s wave or a callout’s tail, an arrow’s shaft, away from a flag’s notch. layout.vertical-align-ignored (warning) reports it once per statement where it moves nothing: on the shapes whose text spot is fixed (triangle, pentagon, star, person, agent, icon), with a centred icon, and on texts, icons, images, groups and lines.
  • One alignment picker. The strip shows a 3 × 3 “Text alignment” grid after Shape for free boxes, three cells for free texts, the written pair pressed and the default greyed; a cell writes the properties that change in one step, and the Theme chip removes both.

Alternatives considered

Section titled “Alternatives considered”
  • - alone, — or ~~ for a line. - is a number’s sign and a - b reads as arithmetic; — is not ASCII (decision 0003 keeps the lexicon ASCII); ~~ is Mermaid’s invisible link.
  • Replacing twoWay by heads. Every consumer would change for no new behaviour.
  • A token that forbids heads, or arrowhead none written by the compiler. draw.io and Excalidraw let a line take an end decoration, the importers would still need arrowhead none for a line with a tail, and the strip could not tell an invented style from a written one.
  • Line tokens in sequence diagrams. Nothing in the profile draws a message without a head.
  • A relation between point endpoints, (x, y) -- (x, y). Statements start with a keyword or an id (decision 0003), routes need a named relation, and the placement would split between the relation and its route.
  • A line shape of a box. place and size give a box, not two points: no bends, no heads, no effects, and a diagonal would be the box’s diagonal.
  • The label as : "Label" after the points, or via (x, y), (x, y) without brackets. A colon clause would be a parser change for one statement, and one via grammar is better than two.
  • A third scene role for lines, or a line registered as both element and relation. Every consumer that switches on role would need the case, or one id would have two entries; an element group with a track needs one rule in planMotion.
  • A Line tool of its own, or arrowhead triangle written literally. A fourth gesture for what the arrow tool already means, and a theme switch would leave a stray triangle on an editorial sheet.
  • rough.js. A download the owner has not approved, randomness not seeded by default, and the renderer’s first dependency.
  • A per-element sketch style. draw.io has it diagram-wide, a mixed picture looks like a mistake, and a theme is where the family puts a look (decisions 0007 and 0013).
  • An SVG filter (feTurbulence, feDisplacementMap). Not deterministic across renderers, dropped by some PDF and video captures, and it would wobble the text.
  • Sketching in the layout’s scene. Every consumer of the geometry would see jittered paths.
  • Naming the hand font before it is bundled. Every sketch picture would carry layout.unmeasured-font and estimated widths, and the snapshots would move twice anyway.
  • verticalAlign on flow nodes, or a pixel offset. Decision 0043 keeps the text properties free-only; an offset is precise but does not know the shape.
  • Two glyph rows or a select for the alignment. Six chips for what draw.io shows as one grid, or words where the strip shows pictures.

Consequences

Section titled “Consequences”

  • The language stays 0.2: the tokens, line, sketch and verticalAlign are additive. Every .model.json snapshot gains heads on each relation and line on each element; the version stays 0.1.

  • The sheets under corpus/import lose their arrowhead none styles and the names that only carried them.

  • New diagnostics: layout.vertical-align-ignored and layout.degenerate-line, both warnings. The syntax.unexpected-character hint names six tokens, and layout.unknown-theme lists eight built-in themes.

  • New public surface: Relation.heads, RelationHeads, RELATION_ARROWS, arrowToken, Element.line, SKETCH_LEVELS, VERTICAL_ALIGNS, Theme.sketch, Scene.sketch, sketchItems, the protocol’s connect.heads, ElementInfo.line, createLine and setLinePoints.

  • An anonymous relation’s key (a->b#1) and a generated id change when statements are reordered, and the wobble of what they name changes with them; named targets keep theirs.

  • Sketched pictures are larger, since each stroked item becomes up to three. Measured on 2026-10-24:

    Picture Clean Sketched
    gallery/free/sketch (embedded fonts, the gallery’s SVG) 136,282 bytes 67,756 bytes
    gallery/free/sketch with --fonts system 6,540 bytes 35,567 bytes
    corpus/acceptance/free/shapes and free/sketch 17,282 bytes 77,695 bytes

    The clean whiteboard is the same sheet rendered with theme "technical.light"; the acceptance pair differs only in its theme, title and heading, and is rendered with system fonts. The fonts dominate an embedded export: Inter in four weights makes the clean file 136 KB, one weight of Patrick Hand makes the sketched file half of it, while the strokes alone grow about five times (the system rows). Nothing but renderSvg reads the sketched paths, and the sketch themes are opt-in.

  • The sketch pictures were regenerated when the hand font landed (the corpus and acceptance SVGs, the gallery sheet and the free/sketch visual reference).