Home: widen the brain layout, fix its entrance, add a clear button to pinned charts

The force layout settled roughly square, so in a wide band the graph sat as a
small island. Vertical centring now pulls nearly three times as hard as
horizontal and the seed sits on an ellipse, which settles at about 2.2:1
without stretching the circles or the edges.

The graph also slid in on load: the rebuild fit ran with a 300ms duration, so
React Flow animated the pan from its default viewport to the content. The fit
is instant now, and the canvas grows in from the centre with `scaleIn` once it
has a layout.

The pinned chart header said "Esc clears", which a phone cannot act on. It
carries the same "× Clear" button as the list header instead; Escape still
works.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017MeiWk3Yq12n2pTvnQWYvt

frontend/src/components/Flow/BrainView.tsx

@@ -17,9 +17,11 @@ import {
   forceY,
   type SimulationNodeDatum,
 } from "d3-force"
+import { motion } from "motion/react"
 import { useEffect, useMemo } from "react"
 
 import type { BrainGraph } from "@/client"
+import { scaleIn } from "@/lib/motion"
 import { BrainEdge } from "./BrainEdge"
 import { BrainNode, type BrainNodeData } from "./BrainNode"
 import "./flow.css"
@@ -46,8 +48,8 @@ type Placed = SimulationNodeDatum & { id: string; size: number; room: number }
  *
  * A live simulation would keep nudging nodes under the pointer while someone is
  * panning, and a graph that never stops moving is unreadable. Starting from a
- * circle rather than d3's own random phyllotaxis also means the same flows lay
- * out the same way twice.
+ * fixed ellipse rather than d3's own random phyllotaxis also means the same
+ * flows lay out the same way twice.
  *
  * `forceX`/`forceY` rather than `forceCenter`: centering only translates the
  * whole thing, so unconnected flows — which is most of them — would push each
@@ -68,8 +70,12 @@ function build(graph: BrainGraph): { nodes: Node[]; edges: Edge[] } {
       id: node.id,
       size,
       room: size / 2 + LABEL_ROOM,
-      x: Math.cos(angle) * radius,
-      y: Math.sin(angle) * radius,
+      // An ellipse, not a circle: the band across Home is far wider than it is
+      // tall, so the layout is meant to come out that way too. Seeding the
+      // shape it should settle into beats making the forces below fight a
+      // circle into one.
+      x: Math.cos(angle) * radius * 1.8,
+      y: Math.sin(angle) * radius * 0.55,
     }
   })
   const links = (graph.edges ?? []).map((edge) => ({
@@ -89,8 +95,13 @@ function build(graph: BrainGraph): { nodes: Node[]; edges: Edge[] } {
       "collide",
       forceCollide<Placed>((node) => node.room),
     )
-    .force("x", forceX(0).strength(0.06))
-    .force("y", forceY(0).strength(0.06))
+    // Centring pulls nearly three times as hard vertically as horizontally, so
+    // the graph compresses into a band roughly twice as wide as it is tall
+    // instead of the square an even pull settles into. Coming out of the
+    // simulation rather than out of a transform keeps the circles round and the
+    // edges the length the link force asked for.
+    .force("x", forceX(0).strength(0.05))
+    .force("y", forceY(0).strength(0.14))
     .stop()
     .tick(300)
 
@@ -144,40 +155,50 @@ function BrainCanvas() {
   useEffect(() => {
     if (!shape) return
     // After the new nodes have been measured, or the fit is of the old ones.
-    const frame = requestAnimationFrame(() =>
-      fitView({ ...FIT, duration: 300 }),
-    )
+    // Instant, never animated: an animated fit travels from React Flow's
+    // default viewport to the content, which on first load is the whole graph
+    // visibly sliding in from the corner.
+    const frame = requestAnimationFrame(() => fitView(FIT))
     return () => cancelAnimationFrame(frame)
   }, [shape, fitView])
 
   return (
-    <ReactFlow
-      nodes={nodes}
-      edges={edges}
-      nodeTypes={nodeTypes}
-      edgeTypes={edgeTypes}
-      nodesDraggable={false}
-      nodesConnectable={false}
-      elementsSelectable={false}
-      proOptions={{ hideAttribution: true }}
-      fitView
-      fitViewOptions={FIT}
-      minZoom={0.1}
-      maxZoom={2}
-      // A band inside a page that scrolls. React Flow claims the wheel by
-      // default, so leaving these on would trap the page under the pointer;
-      // the fit above keeps the whole graph in view without panning anyway.
-      zoomOnScroll={false}
-      zoomOnDoubleClick={false}
-      panOnDrag={false}
-      preventScrolling={false}
-      onNodeClick={(_event, node) => {
-        const [flow] = (node.data as BrainNodeData).flows
-        if (flow)
-          navigate({ to: "/flows/$flowName", params: { flowName: flow } })
-      }}
-      className="brain-flat h-full w-full"
-    />
+    // Held back until there is a layout, so the graph grows in from the centre
+    // of the band it is already fitted to rather than appearing mid-pan.
+    <motion.div
+      variants={scaleIn}
+      initial="hidden"
+      animate={nodes.length ? "visible" : "hidden"}
+      className="h-full w-full"
+    >
+      <ReactFlow
+        nodes={nodes}
+        edges={edges}
+        nodeTypes={nodeTypes}
+        edgeTypes={edgeTypes}
+        nodesDraggable={false}
+        nodesConnectable={false}
+        elementsSelectable={false}
+        proOptions={{ hideAttribution: true }}
+        fitView
+        fitViewOptions={FIT}
+        minZoom={0.1}
+        maxZoom={2}
+        // A band inside a page that scrolls. React Flow claims the wheel by
+        // default, so leaving these on would trap the page under the pointer;
+        // the fit above keeps the whole graph in view without panning anyway.
+        zoomOnScroll={false}
+        zoomOnDoubleClick={false}
+        panOnDrag={false}
+        preventScrolling={false}
+        onNodeClick={(_event, node) => {
+          const [flow] = (node.data as BrainNodeData).flows
+          if (flow)
+            navigate({ to: "/flows/$flowName", params: { flowName: flow } })
+        }}
+        className="brain-flat h-full w-full"
+      />
+    </motion.div>
   )
 }
 
@@ -191,7 +212,7 @@ function BrainCanvas() {
  */
 export function BrainView() {
   return (
-    <div className="h-64 w-full sm:h-80">
+    <div className="h-72 w-full sm:h-96">
       <ReactFlowProvider>
         <BrainCanvas />
       </ReactFlowProvider>