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0033. 0033 — A frame is its size on the canvas

Status: accepted 2026-11-02. Extends 0032.

Context

Section titled “Context”

0032 made a free element read in canvas px and kept drawn frames at two doc px per canvas px “for export”. The inspector then read a frame and its layers in doc px while X/Y were canvas px: a 700×460 frame showed Frame size 1400×920, a 160 px rect W 320, a radius of 12 drew 6 px. Frames from a preset format are worse still: a 1920×1080 doc in a 420 px node. Doc px per canvas px was never one number: drawn 2, hand-resized 1 (a handle drag re-stages the doc at the node size), preset ~4.6.

Figma: a frame’s size is design units; resolution is chosen at export (1×, 2×, 3×…).

Decision

Section titled “Decision”
  1. Design units are canvas px. A frame’s size is its node box. scaleOf(doc, node) in src/lib/motion/units.ts is canvas px per doc px; spaceOf(doc, scale) is the stage every px field of the inspector converts through (frame surface, layers, multi-selection, camera, animate-to). It is the single conversion point of 0032, now fed with the node box for every node, not only free elements. Old docs are not rewritten.
  2. New frames are drawn one doc px per canvas px, as elements and hand-resized frames already were (DOC_PX_PER_CANVAS_PX, draw-create.ts). For them the factor is 1, so agents, MCP and the inspector read the same numbers.
  3. Frame size edits the node. W, H and presets resize the node through the same path as a handle drag (NodePlace.resize → onResize), so the doc follows at one px per canvas px.
  4. Image export scale is of the design size. rowSize takes the design size (doc × docScale); the page or SVG is drawn at row scale × docScale. docScale comes from the node record on the server (docScaleOf, editor.ts) for export_selection and the still export. The dialogs, feega canvas export and the still dialog start at 2×, so a legacy 2× frame exports exactly as before and a new 1× frame as sharp.
  5. Video keeps its resolution. MP4 already picks a short side (720p–4K) independent of the doc; the browser render now scales up to it like the farm (exportSize = outputSize, no cap at the doc size), so 1× docs render as sharp as 2× ones did.
  6. Resizing a frame keeps what is inside it. A resize (handle or typed) keeps the doc px per canvas px the frame had (densityKept, custom-size.ts), applies constraints, and holds type size, strokes and corner radius in px (heldPixels for every frame, not only stills, plus heldRadii: roundness is a share of a layer’s short side, so a stretched surface grew from 12 to 92 px). Typing W on an auto-width text makes it fixed width (resizedTexts, now run on every inspector edit). Wrapping a text in a stack keeps its sizing (TEXT_ITEM, shared with the Figma import).
  7. A library text style is px. The project library holds sizePx; a doc holds the share of its own short side. inLibrary/inDoc (style-library.ts) are the only conversions, so a 16 px style is 16 px in a phone and in a 52 px button. Legacy library entries with size keep their share until edited.
  8. The motion agent and MCP speak canvas px too (amended 2026-11-03). Where tools run (turn.ts, tool-run.ts, motionSummary) the node box gives the scale (docScaleOf, doc-scale.ts) and toolSpace(doc, scale) (tool-space.ts) is the one boundary: its frame feeds every units conversion, toDoc/toCanvas the raw px (arrange offsets, guides, depth, set_canvas sizes), layoutIn/layoutOut the stack gap, padding and fixed tracks. export_image scale 1 is one image px per canvas px. The timeline value fields and project text styles convert through the same scale.

Rejected

Section titled “Rejected”
  • Keeping drawn frames at 2× and converting at every agent tool: ~30 conversion sites in motion-tools.ts. The amendment of 8 converts at one boundary instead: the sites take the toolSpace frame, no per-tool condition.
  • Rescaling the doc for the tool run and back: custom component CSS and stored doc px (blur, depth, gaps) would need a full uniform rescale, lossy on every save.
  • Rescaling old docs to 1× on open (same reason as 0032).
  • A separate 1×/2× control for MP4: the resolution control already is the video’s scale.
  • Defaulting export to each frame’s native density: one more rule; 2× covers the frames people draw. A preset frame denser than 2× exports smaller at 2× than its old 1×; pick 4× or a width.