Sparkline every message a node names

A number in the panel says where a value is, not where it has been. Each
named port in Consumes and Provides now carries a sparkline under it,
fetched once on open and extended from the socket as values arrive, held
to the same 120-point window the server keeps.

Both lists render through the shared port row, so a sink node shows what
flows through it rather than nothing. A flat series draws its mid line
and drops the redundant range label, a lone reading is just its dot, and
a series spanning decades switches to a log scale with the labels left
in real units.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KkmeRiyeYmVZqJVwuyHq9o

frontend/src/components/Flow/MessageSparkline.tsx

@@ -0,0 +1,210 @@
+import { useQuery } from "@tanstack/react-query"
+import { useEffect, useId, useState } from "react"
+
+import type { HistoryPoint } from "@/client"
+import { qualify } from "./deriveEdges"
+import { useLiveValue } from "./liveStore"
+import { messageHistoryQueryOptions } from "./queries"
+
+/** The same bound the server keeps, so the live tail cannot outgrow the window. */
+const WINDOW = 120
+
+/** Room above and below the curve for the stroke, in viewBox units. */
+const PAD = 8
+
+/** Above this ratio a linear series is all baseline and one spike. */
+const LOG_RATIO = 100
+
+/** Short enough for a label, precise enough to tell two of them apart. */
+function compact(value: number): string {
+  const size = Math.abs(value)
+  if (size === 0) return "0"
+  if (size >= 1e6 || size < 1e-2) return value.toExponential(1)
+  return String(Number(value.toPrecision(4)))
+}
+
+/** How a value that cannot be plotted still reads. */
+function describe(value: unknown): string {
+  if (typeof value === "string") return value
+  return JSON.stringify(value) ?? String(value)
+}
+
+/**
+ * The name only settles once typing stops. Without this, every keystroke in the
+ * message field would ask the server for a history.
+ */
+function useSettled(value: string): string {
+  const [settled, setSettled] = useState(value)
+  useEffect(() => {
+    const timer = setTimeout(() => setSettled(value), 400)
+    return () => clearTimeout(timer)
+  }, [value])
+  return settled
+}
+
+/**
+ * Curve and area for a series, in a 0–100 box.
+ *
+ * The awkward series are the point: one reading has no line to draw, a series
+ * that never moved has no span to divide by, and one spanning decades is only
+ * legible once the exponent is what varies.
+ */
+function shape(points: HistoryPoint[]) {
+  const values = points.map((point) => point.value)
+  const low = Math.min(...values)
+  const high = Math.max(...values)
+  // Logs need every reading on the same side of zero.
+  const logged = low > 0 && high / low >= LOG_RATIO
+  const project = (value: number) => (logged ? Math.log10(value) : value)
+  const floor = project(low)
+  const span = project(high) - floor
+
+  const y = (value: number) =>
+    span === 0
+      ? 50
+      : 100 - PAD - ((project(value) - floor) / span) * (100 - 2 * PAD)
+  const x = (index: number) =>
+    points.length === 1 ? 100 : (index / (points.length - 1)) * 100
+
+  const line = points
+    .map(
+      (point, index) =>
+        `${index ? "L" : "M"}${x(index).toFixed(2)},${y(point.value).toFixed(2)}`,
+    )
+    .join(" ")
+
+  return {
+    low,
+    high,
+    line,
+    area: `${line} L100,100 L0,100 Z`,
+    end: y(values[values.length - 1]),
+  }
+}
+
+/**
+ * How one message has been moving, as a sparkline with a live end.
+ *
+ * The panel already knows the current value, so the three silences stay
+ * distinct: nothing has run yet, the message carries something a chart cannot
+ * say anything about, or there is a series to draw.
+ */
+export function MessageSparkline({
+  flow,
+  name,
+}: {
+  flow: string
+  name: string
+}) {
+  const message = useSettled(name)
+  const live = useLiveValue(qualify(flow, message))
+  const { data } = useQuery(messageHistoryQueryOptions(flow, message))
+  const [tail, setTail] = useState<HistoryPoint[]>([])
+  const gradient = useId()
+
+  // Pointing the field at another message makes the collected tail meaningless.
+  // biome-ignore lint/correctness/useExhaustiveDependencies: the name is what invalidates the tail, not anything the effect reads.
+  useEffect(() => {
+    setTail((previous) => (previous.length ? [] : previous))
+  }, [message])
+
+  // Values keep arriving over the socket while the panel is open. Appending
+  // them beats refetching the whole series on every emission.
+  const ts = live?.ts
+  const value = live?.value
+  useEffect(() => {
+    if (typeof value !== "number" || !ts) return
+    setTail((previous) =>
+      previous[previous.length - 1]?.ts === ts
+        ? previous
+        : [...previous, { ts, value }].slice(-WINDOW),
+    )
+  }, [ts, value])
+
+  const fetched = data?.points ?? []
+  // The fetch and the socket overlap; only what the server had not yet seen.
+  const since = fetched[fetched.length - 1]?.ts ?? 0
+  const points = [
+    ...fetched,
+    ...tail.filter((point) => point.ts > since),
+  ].slice(-WINDOW)
+
+  if (points.length === 0) {
+    if (live === undefined) {
+      return (
+        <p className="text-xs text-muted-foreground">
+          Nothing has come through yet.
+        </p>
+      )
+    }
+    return (
+      <div className="flex items-baseline gap-2 text-xs">
+        <span className="min-w-0 flex-1 truncate font-mono">
+          {describe(live.value)}
+        </span>
+        <span className="shrink-0 text-muted-foreground">no history</span>
+      </div>
+    )
+  }
+
+  const { low, high, line, area, end } = shape(points)
+
+  return (
+    // The gap leaves the live dot room to sit on the last reading without
+    // touching the labels.
+    <div className="flex items-center gap-3">
+      <div className="relative h-8 min-w-0 flex-1">
+        <svg
+          viewBox="0 0 100 100"
+          preserveAspectRatio="none"
+          className="h-full w-full overflow-visible"
+          aria-hidden="true"
+        >
+          <defs>
+            <linearGradient id={gradient} x1="0" y1="0" x2="0" y2="1">
+              <stop offset="0%" stopColor="var(--primary)" stopOpacity="0.28" />
+              <stop offset="100%" stopColor="var(--primary)" stopOpacity="0" />
+            </linearGradient>
+          </defs>
+          {points.length > 1 ? (
+            <>
+              <path d={area} fill={`url(#${gradient})`} />
+              <path
+                d={line}
+                fill="none"
+                stroke="var(--primary)"
+                strokeWidth="1.5"
+                strokeLinecap="round"
+                strokeLinejoin="round"
+                // Keeps the stroke even, though the box is far wider than tall.
+                vectorEffect="non-scaling-stroke"
+              />
+            </>
+          ) : null}
+        </svg>
+        {/* The newest reading is always the right edge, so the dot only needs to
+            know how high it sits. */}
+        <span
+          className="pointer-events-none absolute size-3 -translate-x-1/2 -translate-y-1/2 rounded-full bg-primary/20"
+          style={{ left: "100%", top: `${end}%` }}
+        />
+        <span
+          className="pointer-events-none absolute size-1.5 -translate-x-1/2 -translate-y-1/2 rounded-full bg-primary"
+          style={{ left: "100%", top: `${end}%` }}
+        />
+      </div>
+      {/* A shared minimum width, so the curves all end on the same line. */}
+      <div className="min-w-24 shrink-0 whitespace-nowrap text-right font-mono text-xs leading-tight">
+        <div className="font-medium">
+          {compact(points[points.length - 1].value)}
+        </div>
+        {/* A series that never moved has no range worth repeating. */}
+        {low === high ? null : (
+          <div className="text-muted-foreground">
+            {compact(low)}–{compact(high)}
+          </div>
+        )}
+      </div>
+    </div>
+  )
+}

frontend/src/components/Flow/NodePanel.tsx

@@ -23,6 +23,7 @@ import {
 } from "@/components/ui/select"
 import { Switch } from "@/components/ui/switch"
 import { cn } from "@/lib/utils"
+import { MessageSparkline } from "./MessageSparkline"
 import { nodeSourceQueryOptions } from "./queries"
 import { PANEL_SECTION, SidePanel } from "./SidePanel"
 
@@ -177,39 +178,47 @@ function PortList({
       ) : null}
 
       {specs.map((spec, index) => (
-        <div key={`port-${index}`} className="flex items-center gap-1.5">
-          <MessageNameInput
-            value={spec.name ?? ""}
-            suggestions={suggestions}
-            placeholder={`name in ${flow}`}
-            autoFocus={index === freshIndex}
-            onChange={(name) => update(index, { name, port: "" })}
-            onRenamed={onRenamed}
-          />
-          <Select
-            value={spec.dtype ?? "float"}
-            onValueChange={(value) => update(index, { dtype: value as DType })}
-          >
-            <SelectTrigger className="!h-8 w-[92px] text-sm" aria-label="Type">
-              <SelectValue />
-            </SelectTrigger>
-            <SelectContent>
-              {DTYPES.map((dtype) => (
-                <SelectItem key={dtype} value={dtype}>
-                  {dtype}
-                </SelectItem>
-              ))}
-            </SelectContent>
-          </Select>
-          <Button
-            variant="ghost"
-            size="icon-sm"
-            className="text-muted-foreground"
-            aria-label="Remove port"
-            onClick={() => onChange(specs.filter((_, i) => i !== index))}
-          >
-            <X />
-          </Button>
+        <div key={`port-${index}`} className="grid gap-1">
+          <div className="flex items-center gap-1.5">
+            <MessageNameInput
+              value={spec.name ?? ""}
+              suggestions={suggestions}
+              placeholder={`name in ${flow}`}
+              autoFocus={index === freshIndex}
+              onChange={(name) => update(index, { name, port: "" })}
+              onRenamed={onRenamed}
+            />
+            <Select
+              value={spec.dtype ?? "float"}
+              onValueChange={(value) =>
+                update(index, { dtype: value as DType })
+              }
+            >
+              <SelectTrigger
+                className="!h-8 w-[92px] text-sm"
+                aria-label="Type"
+              >
+                <SelectValue />
+              </SelectTrigger>
+              <SelectContent>
+                {DTYPES.map((dtype) => (
+                  <SelectItem key={dtype} value={dtype}>
+                    {dtype}
+                  </SelectItem>
+                ))}
+              </SelectContent>
+            </Select>
+            <Button
+              variant="ghost"
+              size="icon-sm"
+              className="text-muted-foreground"
+              aria-label="Remove port"
+              onClick={() => onChange(specs.filter((_, i) => i !== index))}
+            >
+              <X />
+            </Button>
+          </div>
+          {spec.name ? <MessageSparkline flow={flow} name={spec.name} /> : null}
         </div>
       ))}
     </div>

frontend/src/components/Flow/queries.ts

@@ -12,6 +12,8 @@ export const flowKeys = {
   detail: (name: string) => ["flows", name] as const,
   source: (name: string, nodeId: string) =>
     ["flows", name, "source", nodeId] as const,
+  history: (name: string, message: string) =>
+    ["flows", name, "history", message] as const,
   nodeTypes: ["flows", "node-types"] as const,
 }
 
@@ -36,6 +38,12 @@ export const nodeSourceQueryOptions = (name: string, nodeId: string) => ({
   queryFn: () => FlowsService.readNodeSource({ name, nodeId }),
 })
 
+/** The recent values of one message, for the panel's sparkline. */
+export const messageHistoryQueryOptions = (name: string, message: string) => ({
+  queryKey: flowKeys.history(name, message),
+  queryFn: () => FlowsService.readMessageHistory({ name, message }),
+})
+
 const AUTOSAVE_DELAY = 800
 
 /**