Brain: terracotta for fault, a ring set off from the fill, and a dotted ground

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XC2jX6Hdj7pxGGKzBTrbqB

frontend/src/components/Flow/BrainNode.tsx

@@ -19,21 +19,24 @@ export type BrainNodeData = {
 }
 
 /**
- * Ring thickness as a share of the diameter, measured off the brand mark: a
- * 1.4545 stroke on a 6.3 outer diameter in `fluksio-light.svg`.
+ * The mark's own proportions, measured off `fluksio-light.svg`: a 1.4545 ring
+ * and a 0.4848 gap on a 6.303 outer diameter, leaving the disc the 38.5% in
+ * the middle.
  *
- * A share rather than a fixed width because the neurons run from 32px to 96px:
+ * Shares rather than fixed widths because the neurons run from 32px to 96px:
  * the same ring in pixels would swallow the smallest and read as a hairline on
  * the largest, and it is the proportion that makes a circle look like the mark.
  */
-const RING = 0.23
+const RING = 0.231
+const GAP = 0.077
 
 function BrainNodeComponent({ data }: NodeProps) {
   const { label, kind, members, flows, size, issue } = data as BrainNodeData
   const emits = useGroupEmits(members)
   const failed = useGroupError(members)
-  // One ring for both kinds of trouble: a run that broke and wiring that can
-  // never run are the same answer to "can I trust this neuron right now".
+  // Two faults, told apart the way the mark's two parts are: the ring is the
+  // wiring around the node, so a flow that cannot run as written colours the
+  // ring; the disc is the node itself, so a run that broke colours the disc.
   const problem = failed || !!issue
   // Brightest right after a publish, then left to decay. Only the peak needs
   // holding: the floor is the resting style, so letting go is the whole decay.
@@ -53,11 +56,19 @@ function BrainNodeComponent({ data }: NodeProps) {
         // Nothing seen yet this session is not the same as seen and gone quiet.
         emits === 0 && "brain-idle",
         firing && "brain-hot",
-        problem ? "border-destructive" : "border-foreground",
+        failed && "brain-fault",
+        issue ? "border-brand-secondary" : "border-foreground",
       )}
       // Border-box, so the outer rim stays at `size` and the edges keep landing
-      // on it however thick the ring gets.
-      style={{ width: size, height: size, borderWidth: size * RING }}
+      // on it however thick the ring gets. The gap between ring and disc is an
+      // inset shadow rather than padding: it paints over the fill without
+      // taking part in the layout, so the count stays centred in the disc.
+      style={{
+        width: size,
+        height: size,
+        borderWidth: size * RING,
+        boxShadow: `inset 0 0 0 ${size * GAP}px var(--brain-gap)`,
+      }}
       title={`${label} · ${kind} · ${members.join(", ")}${issue ? ` · ${issue}` : ""}`}
     >
       {/* Remounting on each emit is what restarts the animation. */}
@@ -82,10 +93,14 @@ function BrainNodeComponent({ data }: NodeProps) {
        * A name under every circle is what makes the graph unreadable, so only
        * the neuron under the pointer or the keyboard says what it is — except
        * one with something wrong, since colour is never the only carrier of a
-       * status. Two words rather than the reason itself: a cycle names every
-       * node in it, which is a sentence no label under a 32px circle can hold,
-       * so the phrase matches what Home says and the full text stays in the
-       * tooltip.
+       * status, and here it carries two of them. Two words rather than the
+       * reason itself: a cycle names every node in it, which is a sentence no
+       * label under a 32px circle can hold, so the phrase matches what Home
+       * says and the full text stays in the tooltip.
+       *
+       * The word is `--foreground` rather than the terracotta beside it:
+       * `--brand-secondary` measures 2.2:1 on `--card` in light, which is a
+       * fill colour, not a text colour.
        */}
       <span className={cn("brain-label", problem && "brain-label-on")}>
         <span className="max-w-[140px] truncate text-xs font-medium">
@@ -94,8 +109,10 @@ function BrainNodeComponent({ data }: NodeProps) {
         {/* The label box is only as wide as the circle it hangs under, so two
             words break onto two lines unless told not to. */}
         {problem ? (
-          <span className="whitespace-nowrap text-xs font-medium text-destructive">
-            {failed ? "failed" : "cannot run"}
+          <span className="whitespace-nowrap text-xs font-medium text-foreground">
+            {[failed && "failed", issue && "cannot run"]
+              .filter(Boolean)
+              .join(" · ")}
           </span>
         ) : null}
       </span>

frontend/src/components/Flow/BrainView.tsx

@@ -1,6 +1,8 @@
 import { useQuery } from "@tanstack/react-query"
 import { useNavigate } from "@tanstack/react-router"
 import {
+  Background,
+  BackgroundVariant,
   type Edge,
   type Node,
   ReactFlow,
@@ -209,7 +211,13 @@ function BrainCanvas() {
             navigate({ to: "/flows/$flowName", params: { flowName: flow } })
         }}
         className="brain-flat h-full w-full"
-      />
+      >
+        {/* The same dot grid the editor's canvas uses, quieter and masked back
+            to nothing at the edges — see flow.css. No zoom compensation here:
+            this canvas only ever sits at whatever `fitView` chose and cannot
+            be zoomed, so there is no moiré to chase. */}
+        <Background variant={BackgroundVariant.Dots} gap={24} size={1.5} />
+      </ReactFlow>
     </motion.div>
   )
 }

frontend/src/components/Flow/flow.css

@@ -137,34 +137,71 @@
 .react-flow.brain-flat {
   --xy-background-color: transparent;
   --brain-decay: 90s;
+  /* Thicker than the editor's, to match the weight the mark draws them at. */
+  --xy-edge-stroke-width: 2;
+  --xy-background-pattern-dots-color: color-mix(
+    in srgb,
+    var(--muted-foreground) 22%,
+    transparent
+  );
 }
 
 /*
- * A neuron is the node of the brand mark: a disc of the identity blue inside a
- * thick ring, wired to its neighbours. The ring thickness is a share of the
- * diameter and lives in `BrainNode`, which is where the diameter is known.
+ * The ground the mark's nodes sit on. The band has no surface of its own and no
+ * border, so a dot grid that ran to the edges would draw the rectangle the band
+ * otherwise does not have. An elliptical mask fades it out well before any
+ * edge — the same shape the layout settles into, so the dots run out roughly
+ * where the graph does. The stops are the mask's alpha, not a colour: opaque
+ * keeps the dots, transparent drops them.
+ */
+.brain-flat .react-flow__background {
+  mask-image: radial-gradient(
+    ellipse 62% 62% at 50% 50%,
+    black 0%,
+    transparent 100%
+  );
+}
+
+/*
+ * A neuron is the node of the brand mark: a disc of the identity blue, a gap in
+ * the surface colour, then a thick ring. Ring and gap are shares of the
+ * diameter and live in `BrainNode`, which is where the diameter is known; the
+ * gap is what the mark's tile shows between the two, which here is the card the
+ * band sits flat on.
  *
- * The fill is identity and carries no status — that is the ring's job, and the
- * word under it. What the fill's lightness carries is how recently this page
- * saw the neuron publish: brightest just after it fires, decaying to a floor it
- * never drops below, so a graph left open sorts itself into what is busy and
- * what is not. The floor stays blue enough to still read as the mark. A fresh
- * page has seen nothing either way, so everything starts at `.brain-idle`,
- * halfway, claiming no history it does not have.
+ * The two parts carry the two faults, the way the mark is built: the ring is
+ * the wiring, so a flow that cannot run as written turns it `--brand-secondary`;
+ * the disc is the node, so a run that broke turns the fill the same terracotta.
+ * Both at once still reads, since the gap keeps them apart. This is the one
+ * place terracotta means fault rather than a call to action — see the root
+ * DESIGN-GUIDELINES.md → Colour tokens.
+ *
+ * What the fill's lightness carries is how recently this page saw the neuron
+ * publish: brightest just after it fires, decaying to a floor it never drops
+ * below, so a graph left open sorts itself into what is busy and what is not.
+ * The floor stays saturated enough to still read as the mark. A fresh page has
+ * seen nothing either way, so everything starts at `.brain-idle`, halfway,
+ * claiming no history it does not have.
  */
 .brain-cell {
+  --brain-fill: var(--primary);
+  --brain-gap: var(--card);
   cursor: pointer;
-  background-color: color-mix(in srgb, var(--primary) 50%, transparent);
+  background-color: color-mix(in srgb, var(--brain-fill) 50%, transparent);
   transition: border-color var(--duration-base) var(--ease-standard);
 }
 
+.brain-cell.brain-fault {
+  --brain-fill: var(--brand-secondary);
+}
+
 .brain-cell.brain-idle {
-  background-color: color-mix(in srgb, var(--primary) 65%, transparent);
+  background-color: color-mix(in srgb, var(--brain-fill) 65%, transparent);
 }
 
 /* Snapped into, decayed out of — never the other way round. */
 .brain-cell.brain-hot {
-  background-color: color-mix(in srgb, var(--primary) 90%, transparent);
+  background-color: color-mix(in srgb, var(--brain-fill) 90%, transparent);
   transition: none;
 }
 
@@ -174,17 +211,27 @@
       border-color var(--duration-base) var(--ease-standard),
       background-color var(--brain-decay) linear;
   }
+
+  /*
+   * A fault is a state change, not a falloff. Sharing the decay's transition
+   * would have the disc creep from blue to terracotta over a minute and a half,
+   * so the fill takes the same 200ms the ring beside it does.
+   */
+  .brain-cell.brain-fault {
+    transition:
+      border-color var(--duration-base) var(--ease-standard),
+      background-color var(--duration-base) var(--ease-standard);
+  }
 }
 
 /*
- * Outside the ring rather than in it: the ring is what says whether this neuron
- * can run, and the disc is already `--primary`, so recolouring either to mark
- * the pointer would either overwrite a status or vanish into the fill.
+ * The pointer lights the gap rather than adding a fourth band around a circle
+ * that already has three. Ring and disc both carry a status, so neither can be
+ * recoloured to mark a hover; the surface between them carries nothing.
  */
 .brain-cell:hover,
 .react-flow__node:focus-visible .brain-cell {
-  outline: 2px solid var(--ring);
-  outline-offset: 2px;
+  --brain-gap: var(--ring);
 }
 
 /*
@@ -215,18 +262,23 @@
  * The same falloff as the neurons, on the connection instead of the disc. It
  * carries the line and its two end dots alike, so the ink is a variable on the
  * group they share rather than a stroke on each.
+ *
+ * Drawn from `--foreground`, the same token as the rings: in the mark a
+ * connection is the same stroke as the ring it runs into, and mixing the two
+ * families instead left the graph looking like rims in one drawing and wires
+ * from another.
  */
 .brain-wire {
-  --brain-ink: color-mix(in srgb, var(--muted-foreground) 38%, transparent);
+  --brain-ink: color-mix(in srgb, var(--foreground) 32%, transparent);
 }
 
 .brain-wire.brain-idle {
-  --brain-ink: color-mix(in srgb, var(--muted-foreground) 55%, transparent);
+  --brain-ink: color-mix(in srgb, var(--foreground) 48%, transparent);
 }
 
 /* Snapped into, decayed out of — never the other way round. */
 .brain-wire.brain-hot {
-  --brain-ink: color-mix(in srgb, var(--muted-foreground) 85%, transparent);
+  --brain-ink: color-mix(in srgb, var(--foreground) 80%, transparent);
 }
 
 .react-flow__edge-path.brain-edge {