A tab should show where your click will land.

The question was rewritten as a job, with no solution in it: show where a click will land, without adding noise for someone who switches tabs all day.

That ruled out anything loud: a hint people see all day has to stay subtle, or it becomes noise.

How the ideas were found

The search looked at how other fields already do this job: sixteen ideas in a first round, three more in a second. AI agents scored each one against a checklist, twice. Six are shown above.

What the Seed is

• Short like the stitch: a third of the tab, at least 24 pixels.
• Soft at both ends like the faint line, and lighter than the underline.
• Only when the pointer stops, as cockpits do: after 80 milliseconds of rest, so sweeping across the row shows nothing.

It led the second round at 90.6%. It sits exactly where the underline will go, like a seed of it.

By hand, and with AI

The name was mine. I pointed at a card on a board and asked if it could be called the Seed; it became the name of the whole idea. The card itself was drawn by an AI agent.

I also caught two board errors: one said an idea came from the first round when it came from the second, and one gave the faint line the wrong origin. And I asked why the pill that follows the pointer seemed missing from the scoring. It had scored 60%, joint 11th of 16, and the boards now quote the scoring's real lines instead of paraphrases.

A slow-motion switch, five times slower, let me judge the motion by eye before anyone argued about it.

My idea that I set aside

The Hybrid was my proposal: slide for nearby tabs, grow in place for far ones. It was built, annotated in the prototype, and set aside, because the same click could look different depending on how far away the tab was. It is the third row in the clip.

Who did what

AI agents built all three behaviours, recorded the clips and scored them. The choice was mine, made by eye. A result this close is reported as a tie.

Not proven yet

The 80 millisecond pause and the 24 pixel minimum come from research, not from watching people. Nobody outside the project has used it.

The sweep had checked that the row of tabs scrolls sideways at phone width, and stopped there. It never asked what the scrolling hides.

Two more failures, not pictured: clicking a half-hidden tab opened it but left it half hidden, and the keyboard could land on a tab with two thirds of it out of view.

Too many tabs became its own piece of work, and later moved inside the Tabs component rather than a separate pattern.

My questions about limits also raised tab names people type themselves, as in custom dashboards. That became a second new section in the same skill, "names people choose". Rules for long names are proposed (a 64 character limit, a 240 pixel cap, the full name on hover) but not decided.

Five directions were scored. Both leaders share the same base: the open tab sticks to the left edge, every tab stays a real tab in one scrolling row, and nothing moves except by scrolling.

The cost of my choice was real: a small new list component, the Dropdown List, added to Vela as Experimental rather than going without it. Reading the menu library's source, the spec agent found it blocks the rest of the page by default and doesn't move focus to the current item, which became two rules in the spec.

Only the version of Tabs built on Base UI, an open-source behaviour library, gets the list. The version with no dependencies keeps a plain scrolling row.

Five rules that keep it calm

• One thin line, unbroken, as it is today.
• One line high. Nothing sits below the row.
• No new shapes. No pills, circles or dividers.
• Edges are fades, not lines, except in high-contrast mode, where fades disappear.
• Nothing appears until it's needed. When every tab fits, the row is exactly today's.

The arrow buttons went too. The list reaches any tab in two clicks, and swiping, trackpads and the keyboard still scroll the row.

The chevron

It started from my own flying-bird chevron on omkarux.com. An AI agent made six Vela-sized versions, two of them birds, and I chose the calm one over the springy one: one wingbeat in under a quarter of a second. It never points sideways and stays still when opened from the keyboard. It is decided, not built.

What a sketch couldn't show

Rendering the list with Vela's real styles, the AI agent measured two problems in dark mode: the hover colour matched the background exactly, and a link colour was too faint to read as text. Both now have a fix: a new colour token and a rule.

The thin underline. The row of tabs can scroll sideways, and a scrolling area cuts off anything past its edge. The underline's lower pixel was cut. Nobody noticed because the automatic screenshot checks allow up to 1% of pixels to differ, and one thin row is less than that. A new browser test measures the underline and fails on the old code.

High contrast. Windows has a mode for people who need stronger contrast. It swaps the page's colours for the system's own and makes hidden lines visible, so every tab grew an underline.

Both were found by the AI-run sweep. Both fixes are merged, each with a new browser check that fails on the old code.