The canvas placed nodes with dagre, which orders nodes but knows nothing
about ports: an edge leaves a particular handle and lands on a particular
one, so two producers feeding a consumer in the other order crossed just
before they landed however well the nodes were arranged. The graph was not
a multigraph either, so two messages between one pair of nodes collapsed
into one before crossings were counted, and the endpoint labels were laid
out as 220-wide cards with every handle stacked on a single pixel.
ELK's layered algorithm replaces it. Every declared port is handed to it as
a fixed point on the node's rim, at the fraction `portFraction` puts the
handle at — which the node components now render from the same function —
so what the crossing count is minimised over is what ends up on the screen.
Measured on this installation's flows, with the labels included: `home`
goes from 51 crossings to 6 across and 70 to 29 down, `demo_training` 27 to
5 and 59 to 32, and every graph is the same size or smaller.
The engine answers asynchronously and is a chunk of its own, so positions
became state: the canvas draws nothing until the first layout lands, and an
edit keeps the arrangement it had rather than flashing through the corner.
The entry chunk is untouched and the flow route's own chunk came down 167
to 121 kB, since dagre used to be in it.
Two things the crossings made worse come with it. A hovered edge resolves
to full strength so one line can be followed through a busy rank, and a
feedback edge — one whose target the layout put behind its source — swings
out into a lane beside the graph instead of being drawn through everything
between its ends, which is what "House history" was reported for.
- A node's height follows the ports on its busiest side. It is a function of
the document, so `layoutGraph` reserves exactly what is drawn and nothing
measured is fed back into the layout.
- The three status controls now sit in slots that are there whether the
control is or not. A node running many times a second mounted and unmounted
the stop button on every execution, resizing the card each time.
- A port bound to another flow's message is drawn as a label, naming the node
at the far end and its type. Only the opposite direction was answered
before. The scan behind both is now cached on the store's commit counter
rather than reading every flow per request.
Two things the first pass got wrong.
The Changes and "Given up on" lists had no cap, so they ran as long as the
audit trail did — and worse, a truncating flex row still offers its whole
unwrapped line as a min-content contribution, so the card sized itself to the
longest entry and took the page sideways with it. Both now use the same
capped, scrolling box the runs and failures lists already had, which fixes the
length and the width together.
Running downwards, a rank of eight nodes was two thousand pixels across
because a node box is landscape: siblings cost a rank four times as much
across as they do down it. A rank wider than two now wraps onto the ranks
below, settling over a few passes since wrapping one rank pushes what was
under it up into the room that freed. The value chip on an edge no longer
reserves its width there either — that width is spent across the screen rather
than along the flow, and the rank gap it would widen is already wider than the
chip is tall. The same flow that laid out 2040x216 is now 803x722; a chain and
a diamond are unchanged, and so is every desktop layout.
The canvas lays itself out: a layered graph, left to right on a desktop and
top to bottom on a phone, with room reserved for the value each edge carries.
Nodes cannot be dragged and `NodeDef.position` is gone from the document —
a graph nobody can arrange is one worth keeping small, which is what keeps
flows atomic. Endpoints join the same layout, so their lanes and the
localStorage that remembered where they were dragged go too.
Mobile, per the new Responsive section of DESIGN-GUIDELINES.md: the dock caps
its width and wraps instead of running off the screen, the dashboard stacks
into one column rather than shrinking a wall panel to a fifth of its size, and
Home stops widening its grid track past the viewport. A Playwright project at
a phone's width fails the build when a screen no longer fits.
Along the way: publish is the checkmark that was already there rather than a
button that appears and disappears, with discard beside it on both the flow
and the dashboard; the brain reveals a neuron's name on the first tap; and the
port sparklines get room to breathe.
stroblme