Design Philosophy

VS Code Design Philosophy

This skill is the canonical VS Code design philosophy — the single source of truth for how we reason about UI, for both developers and agents.

As more and more of the UI is implemented via agents and tooling, the pixels increasingly take care of themselves, and the scarce, human part becomes the design judgment behind them.

This is about shifting left - talking about UI in design terms, not pixels, and having that conversation early. When something looks off, "this is 8px, should be 6px" fixes one number; "this surface is rounded at the wrong elevation tier" names the rule, so the fix lands everywhere and we catch it on a mockup or screenshot rather than in code review. The aim is to agree on what the UI should be and why, in language a designer and an engineer can share - the implementation (which token, which file) tends to follow once the design is settled.

How to read this: three layers

The hardest part of any design language is getting from "this feels off" to a clear, shared fix everyone agrees on. This bridges that in three steps, each explaining the one below it:

Read top-down when you're learning the system, and bottom-up when you're fixing a bug: name the feeling, find the principle it breaks, then reach for the move that restores it.

Worked example - a busy panel

• See: a panel feels busy and keeps pulling your eye off the editor.
• Feeling: not Calm, not Focused.
• Principle: breaks Quiet at rest (it carries a permanent fill it shouldn't) and One thing leads (secondary chrome competing with the editor).
• Move: drop the panel to a recessed/transparent background token, reveal its border only on hover, and demote its labels to a quieter type role.

The values: what we design for

These four values name what we want people to feel using VS Code - they're the top layer, the thing every principle and move below is ultimately in service of. Learn them and you can describe almost any bug. Each is a feeling the UI should give; each is upheld by one or more principles below. Reach for the value first, the principle second, the move last.

Say "this feels noisy, it's not Calm" before "the background should be transparent." The value points everyone at the same principle.

Why these four?

It's fair to ask: who would ever want a UI that isn't calm, focused, consistent, and delightful? That's exactly the point. These aren't differentiators we're claiming over other products - they're the qualities most under threat in a tool like ours, and naming them is how we defend them. We chose them because they're the values VS Code is structurally inclined to lose:

• Calm is the first casualty of an IDE. VS Code is information-dense and lived in for hours; every feature team has a good reason to add one more affordance, and the sum is noise. Calm is the value that pushes back on our own gravity.
• Focused matters because our surfaces are deep. A screen full of equally-weighted, equally-valid controls is the default failure mode of a power tool. Naming focus forces us to decide what leads.
• Consistent has the largest surface area to defend. VS Code is built by many hands over many years; drift is the natural state. Consistency is less an aspiration than a maintenance discipline.
• Delightful is the one we deliberately ration. It earns its place only by doing a job (Principle 7). We name it not to add more polish but to keep it honest, so delight guides and confirms rather than decorates.

And each value names a real tension, not a free win - which is what makes it a choice worth stating rather than a platitude:

• Calm trades against density - how much do we surface at rest?
• Focused trades against equal access - what do we demote so one thing can lead?
• Consistent trades against the genuinely special case - when is a difference earned rather than drift?
• Delightful trades against restraint - when does a flourish cross into noise?

So the useful question isn't "would we ever not want these?" but "which one is this surface trading away, and did we mean to?" When a value really must yield - say, a critical warning that should break calm to seize attention - that's a deliberate, named exception, not a reason to drop the value.

Principles

Principles are evaluative: each one is a question you can ask of any surface, and the answer tells you whether the design is right - independent of any pixel value. They're grouped by the value they uphold.

Calm

1. Quiet at rest, present on intent

Ask: is anything shouting when nothing is happening?

Chrome should recede until you engage it. A surface carrying a permanent fill, border, or focus ring it hasn't earned is competing with the user's content for attention it doesn't need. The modern look is restrained: things reveal themselves on intent - hover, focus, interaction - and sit quietly otherwise.

When this is wrong it sounds like "this is loud at rest / should be quiet until hover" or "the focus ring is firing on click" - a behavioral description, not a color value.

Carried out by: reveal-on-intent behaviors, one stroke, theme color.

2. Room to breathe

Ask: does this feel cramped, tight, or jagged?

Calm UI is generous and soft. Space isn't wasted; it's what lets the eye rest and groups things without drawing a single line. Edges are rounded rather than sharp. When a surface feels boxed-in or busy, the fix is usually more breathing room on the spacing ramp, not smaller content.

Carried out by: the spacing ramp, elevation tiers (rounded, not sharp).

3. The interface explains itself, plainly and kindly

Ask: could someone understand this at a glance, without guessing?

The UI should read like a person talking. Prefer a word to a mystery glyph; write in sentence case; keep the tone human. A lone unlabeled icon, or a Title-Cased Marketing Headline, makes the user work harder than they should - never cryptic, never shouting.

Carried out by: words & casing.

Worked example - a boxed-in toolbar

• See: a toolbar sits on a solid filled bar, separator lines between every button, the buttons pushed up against each other.
• Feeling: not Calm - busy and boxed-in.
• Principle: breaks Quiet at rest (the fill and separators are permanent chrome that hasn't earned its place) and Room to breathe (buttons jammed together).
• Move: let the bar read transparent at rest, drop the separators (one stroke - and here the answer is no), and space the buttons out on the ramp.

Focused

4. One thing leads; the rest supports

Ask: where does the eye go first - and is anything secondary competing with it?

Every view should have a clear center of attention - the one thing the eye should land on first. Keep secondary information out of that spot: demote it with a quieter type role, a recessed surface, or a smaller icon, so the thing that matters leads and everything else supports it. A view where everything has equal weight is flat - the eye has nowhere to go.

Carried out by: type roles, elevation tiers, icon size by context.

5. Elevation is encoded, not eyeballed

Ask: does this surface's roundness match how far it floats above what's beneath it?

How rounded - and how raised - a surface is means something: it tells you where the surface sits in the stack. A floating overlay reads as more rounded than a control sitting flat inside a pane. Radius is chosen by the surface's role in the hierarchy, never by taste. (This serves both Focused and Consistent.)

Carried out by: elevation tiers, reveal-on-intent (scroll shadows).

Worked example - a flat settings row

• See: a settings row shows its label, its help text, and a "Reset" action all at the same size and weight.
• Feeling: not Focused - flat; the eye doesn't know where to land.
• Principle: breaks One thing leads - nothing is the center of attention.
• Move: lift the label to the leading type role, demote the help text to body2, and make "Reset" a quiet secondary action so the row reads top-down.

Consistent

6. Sameness signals sameness

Ask: do two like things look identical - and is any difference here intentional?

Equivalent elements must look equivalent, because they pull from the same named scale. When two similar things differ, that difference should mean something; accidental drift is the enemy. This is why every size, radius, weight, and color is a named token with a role, not a literal - the literal is only ever a stand-in for the token it lands on.

Carried out by: every move below - they are the shared scales. See especially design tokens, the spacing ramp, the type ramp, icon sizes, one stroke.

Worked example - two mismatched dialogs

• See: two dialogs open side by side; one has 8px corners, the other 6px - both are floating overlays.
• Feeling: not Consistent - the UI feels like it's drifting.
• Principle: breaks Sameness signals sameness (two equivalent surfaces look different for no reason) and Elevation is encoded (an overlay belongs on the Outer tier).
• Move: point both at the Outer radius token; the 6px was a literal someone typed instead of naming the tier.

Delightful

7. Delight earns its keep

Ask: what does this help the user do?

Motion, reveals, and finishing touches are welcome - but each must do a job: guide the eye, confirm an action, orient the user, or smooth a jump. If there's no answer to the question, it's decoration, and decoration reads as noise (back to Calm). Keep it subtle, short, and interruptible; honor prefers-reduced-motion; never animate for its own sake.

A delight bug sounds like "this transition is doing nothing for me" (cut it) or "this jump is disorienting - it needs a functional transition" (add one) - not a duration or easing value to fiddle with.

Carried out by: reveal-on-intent behaviors.

Worked example - a bouncing panel

• See: a side panel slides in with a 600ms bounce every time you toggle it.
• Feeling: not Delightful (gimmicky) and not Calm (slow and shouty).
• Principle: breaks Delight earns its keep - the bounce isn't doing a job, and the toggle is already obvious.
• Move: if nothing needs orienting, cut the animation; if the panel's arrival genuinely needs explaining, replace it with a short, subtle, interruptible fade that honors prefers-reduced-motion.

The moves: the mechanical toolbox

Moves are the concrete mechanics - the tokens, ramps, and tiers. On their own they're just lists of allowed values; what makes each one usable is the decision rule that says which value, and why, plus the principle it serves. When you reach for a move, lead with the rule, not the literal.

This is the one section that touches implementation - and even here, the goal is to keep the conversation about design. Treat the Moves as the shared vocabulary that lets an agreed design be built consistently, not as the opening move in a review. Reach for them after you've named the feeling and the principle, never instead of it.

The size tokens live in baseSizes.ts and the font ramp in sizes.ts; the full reference is in design-tokens.instructions.md.

Tokens are the source of truth, not the pixel

Design-system spacing, radii, type roles, and colors should use a named token or ramp where one exists. Raw literals remain valid for structural measurements.

• Decision rule: when something looks wrong, find the token it should be expressing and reason about that - not the literal.
• Serves: Sameness signals sameness (6).

An 8px corner isn't "8px." It's an Outer surface radius that someone typed as a literal. Name the role and the fix follows.

Elevation tiers - round by role, not by literal

Corner radius encodes how far a surface floats above the one beneath it. Every rounded thing belongs to exactly one tier:

Pills (radius ≈ half the height) are fully round (--vscode-cornerRadius-circle), not "a big radius."

• Decision rule: pick the tier by the surface's role in the stack, not by how the corner looks. A bug here sounds like "this overlay is rounded at the control tier," never "this needs more border-radius."
• Serves: Elevation is encoded (5), Room to breathe (2).

The spacing ramp - on-scale or off-scale

Padding, margin, and gap come from the spacing ramp (0, 2, 4, 6, 8, 10, 12, 16, 20, 24, 28, 32, 36, 40).

• Decision rule: a value either lands on the ramp or it doesn't. Off-scale values (3, 5, 7, 14, 26…) break the rhythm; snap to the nearest step, ties rounding up. Report rhythm bugs as "this is off the spacing ramp," not "add a couple of pixels."
• Serves: Room to breathe (2), Sameness signals sameness (6).

The type ramp - roles and two weights, not free sizes

Text styles are roles, not arbitrary sizes: heading1–3, body1–2, label1–3. There are exactly two weights - regular (400) and semiBold (600). There is no medium (500). "Strong" is not a bigger size; it is the same role token at semiBold.

• Decision rule: choose the role by the text's rank in the hierarchy, not by eyeballing a size. A heading that looks weak is "the wrong type role" or "missing the semiBold weight," not "bump the font to 14." A 500 anywhere is off the ramp.
• Serves: One thing leads (4), Sameness signals sameness (6).

Icon sizes - two sizes, chosen by context

Codicons are 16px (base) or 12px (compact) - nothing in between; 14px is always a bug. At the compact size, also swap to the *Compact glyph (Codicon.close → Codicon.closeCompact) so the icon is optically tuned, not just scaled.

• Decision rule: size tracks the density and rank of the context. Use base (16px) for standalone or primary actions and comfortable click targets; use compact (12px) for dense rows, inline glyphs, and secondary chrome where the icon rides alongside text. So the answer to "16 or 12?" is "what is this icon's role here?" - not a taste call. Say "this icon should be compact," not "shrink it a bit."
• Serves: One thing leads (4), Sameness signals sameness (6).

One stroke

The standard border/separator stroke is 1px (--vscode-strokeThickness).

• Decision rule: whether an ordinary border is present is a yes/no decision. Preserve thicker semantic or accessibility strokes, such as focus indicators.
• Serves: Quiet at rest (1), Sameness signals sameness (6).

Color comes from the theme

Every color is a --vscode-* theme token, so the UI tracks the active theme and high-contrast modes.

• Decision rule: a hardcoded hex is a bug by construction. Color bugs are "wrong theme token" (or "a token that disappears in light/HC"), never a hex value to nudge.
• Serves: Quiet at rest (1), Sameness signals sameness (6).

Reveal-on-intent behaviors

Chrome that used to carry a permanent fill now reads transparent at rest and only reveals on interaction. Each behavior also does a job, so they pull double duty:

• commandCenter - transparent at rest; shows its background/border on hover, so a pointer confirms the thing it's over.

• statusBar - neutralized to the window; only the background changes on hover, the foreground stays put.

• keyboardFocusOnly - the focus ring appears for keyboard focus (:focus-visible), not on mouse click, so the affordance shows exactly when it's useful.

• scrollShadows - content fades under a surface edge instead of being cut at a hard line, so you feel there's more beyond the fold.

• Serves: Quiet at rest (1), Delight earns its keep (7), and (scroll shadows) Elevation is encoded (5).

Words & casing

Prefer a text label to an icon. A word is read; an icon is guessed. Reach for a glyph only when its meaning is near-universal (close, search) or space is genuinely scarce - otherwise label the thing, or pair icon + label when you need both recognition and recall. A lone mystery glyph is the bug, not a badly-chosen one: "this action is unlabeled - give it a word," not "find a clearer icon."

Write in sentence case. Labels, buttons, menus, and messages capitalize the first word and proper nouns only - "Start new session," not "Start New Session." It's calmer, friendlier, and quicker to scan. Report it as "this is Title Case - make it sentence case," a tone fix, not a reword.

⚠️ Known conflict - reconcile later. This sentence-case guidance is the intended modern-UI direction, but it contradicts the repo-wide coding guideline that mandates title-style capitalization for command labels, buttons, and menu items (see coding-guidelines.instructions.md, "UI labels"). The two conventions have not yet been reconciled. Until they are, follow the existing title-case rule for shipped, non-experimental UI, and apply sentence case only within surfaces that have explicitly adopted the modern UI direction. TODO: agree a single casing convention and update whichever doc loses.

• Serves: The interface explains itself (3).

The phrasebook: describe the bug, name the principle

Lead with the role / tier / ramp, not the number - then name the principle so the fix lands everywhere, not just here. The number is a symptom.

Giving and receiving feedback

Describe the design, not the pixel. When you name the rule that's broken, the fix lands everywhere it's broken - not just in the one spot you happened to notice.

When something looks wrong, say it in this order:

1. The feeling - which of the four values is it missing? Calm, Focused, Consistent, Delightful.
2. The surface - what and where? "the sidebar pane header," "the Save dialog."
3. The principle it breaks - the rule behind the feeling.
4. The move that would fix it - the mechanic that restores it.
5. Only then, if useful, the number - "shows 4px, looks like it wants 6px."

Example "The activity bar doesn't feel Calm - it's loud at rest. The icons carry a permanent fill that's competing with the editor (Quiet at rest, present on intent). Could the fill reveal on hover instead? It reads about 2px too tight as well, but the fill is the real thing."

Lead with the feeling, not the fix

The word points everyone at the same principle, even before anyone agrees on a pixel:

What makes feedback hard to act on

These aren't wrong, they're just incomplete - they fix one spot and drift back out of sync:

• A bare number. "This should be 6px." Which token? Why? Name the role and the fix lands everywhere.
• A taste claim with no rule. "I don't like this corner." Tie it to a value or principle so it's a shared standard, not a preference.
• A fix with no feeling. "Make it transparent." Maybe - but say what's wrong first ("it's loud at rest"), so we fix the cause, not just this instance.
• Several things at once. Split "this panel is busy, off-grid, and the icon's wrong" into three, each with its own value.

Practical notes

• Attach the surface. A screenshot or a short clip (for motion) plus the name of the view beats a paragraph of description. Circle the spot.
• One observation per thread. Keep each piece of feedback to a single surface + value, so it can be discussed and resolved on its own.
• Light vs. dark vs. high-contrast. If something only breaks in one theme, say so - that usually points at a theme token problem, not a color choice.
• Reduced motion. For animation feedback, note whether you have prefers-reduced-motion on; a transition should still make sense without it.