diff --git a/src/lib/render.ts b/src/lib/render.ts
new file mode 100644
index 0000000..77cf395
--- /dev/null
+++ b/src/lib/render.ts
@@ -0,0 +1,163 @@
+import { type GpuMetricKind } from "./metrics-parser";
+import { type ModelRuntimeState } from "./inflight-tracker";
+import { escapeXml, shorten } from "./util";
+
+export function svgDataUrl(svg: string): string {
+  return `data:image/svg+xml;base64,${Buffer.from(svg).toString("base64")}`;
+}
+
+const METRIC_LABEL: Record<GpuMetricKind, string> = {
+  util_percent: "UTIL",
+  memory_util_percent: "VRAM",
+  temperature: "TEMP",
+  power: "PWR",
+  fan: "FAN",
+};
+
+export interface InflightRenderOptions {
+  modelName: string;
+  state?: ModelRuntimeState;
+  count: number;
+  offline: boolean;
+  pulse: boolean;
+}
+
+export function renderInflight(opts: InflightRenderOptions): string {
+  const name = escapeXml(shorten(opts.modelName));
+
+  if (opts.offline) {
+    return frame("#3a3a3a", [
+      centerText("!!", 34, 20, "bold", "#e0e0e0"),
+      centerText("OFFLINE", 52, 9, "normal", "#bdbdbd"),
+      centerText(name, 64, 7, "normal", "#ffffff"),
+    ]);
+  }
+
+  if (opts.modelName === "unset") {
+    return frame("#222222", [
+      centerText("?", 36, 16, "bold", "#888888"),
+      centerText("NO MODEL", 54, 8, "normal", "#666666"),
+    ]);
+  }
+
+  if (!opts.state) {
+    return frame("#222222", [centerText("…", 36, 16, "bold", "#999999"), centerText(name, 60, 7, "normal", "#999999")]);
+  }
+
+  const isActive = opts.state === "ready" && opts.count > 0;
+  const bg = opts.state === "ready" ? (isActive ? "#8b2626" : "#1e6b34") : opts.state === "loading" ? "#8a6d1d" : "#3a3a3a";
+  const label = opts.state === "ready" ? (isActive ? "ACTIVE" : "IDLE") : opts.state === "loading" ? "LOADING" : "OFF";
+  const opacity = isActive && opts.pulse ? 0.55 : 1;
+
+  return frame(bg, [
+    centerText(label, 38, 18, "bold", "#ffffff", opacity),
+    centerText(name, 64, 7, "normal", "#ffffff"),
+  ]);
+}
+
+export interface GpuGraphRenderOptions {
+  gpuName: string;
+  metric: GpuMetricKind;
+  value: number | undefined;
+  history: number[];
+  offline: boolean;
+}
+
+export function renderGpuGraph(opts: GpuGraphRenderOptions): string {
+  const label = escapeXml(shorten(opts.gpuName));
+
+  if (opts.offline) {
+    return `<svg xmlns="http://www.w3.org/2000/svg" width="72" height="72" viewBox="0 0 72 72">
+  <rect width="72" height="72" fill="#3a3a3a"/>
+  <text x="36" y="30" text-anchor="middle" font-family="Arial,sans-serif" font-size="18" font-weight="bold" fill="#e0e0e0">!!</text>
+  <text x="36" y="46" text-anchor="middle" font-family="Arial,sans-serif" font-size="9" fill="#bdbdbd">OFFLINE</text>
+  <text x="36" y="62" text-anchor="middle" font-family="Arial,sans-serif" font-size="7" fill="#ffffff" opacity="0.9">${label}</text>
+</svg>`;
+  }
+
+  const color = opts.value === undefined ? "#666666" : severityColor(opts.metric, opts.value);
+  const valueText = opts.value === undefined ? "--" : `${Math.round(opts.value)}${unit(opts.metric)}`;
+  const points = chartPoints(opts.history, opts.metric);
+
+  const line =
+    points.length > 1
+      ? `<polyline points="${points.map((p) => `${p.x},${p.y}`).join(" ")}" fill="none" stroke="${color}" stroke-width="2" stroke-linejoin="round" stroke-linecap="round"/>`
+      : "";
+
+  const area =
+    points.length > 1
+      ? `<path d="M ${points.map((p) => `${p.x},${p.y}`).join(" L ")} L ${points[points.length - 1].x},55 L ${points[0].x},55 Z" fill="url(#grad)" opacity="0.35"/>`
+      : "";
+
+  return `<svg xmlns="http://www.w3.org/2000/svg" width="72" height="72" viewBox="0 0 72 72">
+  <defs>
+    <linearGradient id="grad" x1="0" y1="0" x2="0" y2="1">
+      <stop offset="0%" stop-color="${color}" stop-opacity="0.9"/>
+      <stop offset="100%" stop-color="${color}" stop-opacity="0"/>
+    </linearGradient>
+  </defs>
+  <rect width="72" height="72" fill="#10131a"/>
+  <rect x="1" y="18" width="70" height="40" fill="none" stroke="#242b38" stroke-width="1"/>
+  <line x1="1" y1="55" x2="71" y2="55" stroke="#242b38" stroke-width="1"/>
+  ${area}
+  ${line}
+  <text x="36" y="11" text-anchor="middle" font-family="Arial,sans-serif" font-size="11" font-weight="bold" fill="${color}">${valueText}</text>
+  <text x="36" y="67" text-anchor="middle" font-family="Arial,sans-serif" font-size="7" fill="#8b93a5">${METRIC_LABEL[opts.metric]} · ${label}</text>
+</svg>`;
+}
+
+function unit(metric: GpuMetricKind): string {
+  return metric === "temperature" ? "°C" : metric === "power" ? "W" : "%";
+}
+
+function severityColor(metric: GpuMetricKind, value: number): string {
+  if (metric === "temperature") return value >= 80 ? "#e0453a" : value >= 60 ? "#d9a02a" : "#3fae5a";
+  if (metric === "power") return value >= 300 ? "#e0453a" : value >= 150 ? "#d9a02a" : "#3fae5a";
+  return value >= 85 ? "#e0453a" : value >= 50 ? "#d9a02a" : "#3fae5a";
+}
+
+function chartPoints(history: number[], metric: GpuMetricKind): { x: number; y: number }[] {
+  const n = history.length;
+  if (n === 0) return [];
+  const left = 3;
+  const right = 69;
+  const top = 20;
+  const bottom = 55;
+  const yMax = yScaleMax(metric, history);
+  return history.map((v, i) => {
+    const x = n === 1 ? (left + right) / 2 : left + ((right - left) * i) / (n - 1);
+    const clamped = Math.max(0, Math.min(v, yMax));
+    const y = bottom - ((clamped - 0) / (yMax - 0 || 1)) * (bottom - top);
+    return { x: round1(x), y: round1(y) };
+  });
+}
+
+function yScaleMax(metric: GpuMetricKind, history: number[]): number {
+  if (metric !== "power") return 100;
+  const maxValue = Math.max(...history);
+  if (!isFinite(maxValue) || maxValue <= 0) return 100;
+  return niceCeil(maxValue * 1.1);
+}
+
+function niceCeil(value: number): number {
+  const magnitude = Math.pow(10, Math.floor(Math.log10(value)));
+  for (const m of [1, 2, 2.5, 5, 10]) {
+    if (m * magnitude >= value) return m * magnitude;
+  }
+  return value;
+}
+
+function round1(value: number): number {
+  return Math.round(value * 10) / 10;
+}
+
+function centerText(text: string, y: number, size: number, weight: "normal" | "bold", fill: string, opacity?: number): string {
+  return `<text x="36" y="${y}" text-anchor="middle" font-family="Arial,sans-serif" font-size="${size}" font-weight="${weight}" fill="${fill}"${opacity === undefined ? "" : ` opacity="${opacity}"`}>${text}</text>`;
+}
+
+function frame(bg: string, parts: string[]): string {
+  return `<svg xmlns="http://www.w3.org/2000/svg" width="72" height="72" viewBox="0 0 72 72">
+  <rect width="72" height="72" fill="${bg}"/>
+  ${parts.join("\n  ")}
+</svg>`;
+}
diff --git a/tests/render.test.ts b/tests/render.test.ts
new file mode 100644
index 0000000..4011e19
--- /dev/null
+++ b/tests/render.test.ts
@@ -0,0 +1,78 @@
+import assert from "node:assert/strict";
+import { test } from "node:test";
+import { renderGpuGraph, renderInflight, svgDataUrl } from "../src/lib/render";
+
+test("svgDataUrl wraps an SVG as a base64 data URL", () => {
+  const url = svgDataUrl("<svg></svg>");
+  assert.match(url, /^data:image\/svg\+xml;base64,/);
+});
+
+test("renderInflight: ready + count renders IDLE in green", () => {
+  const svg = renderInflight({ modelName: "Qwen3.8-27B-NVFP4", state: "ready", count: 0, offline: false, pulse: false });
+  assert.match(svg, /IDLE/);
+  assert.match(svg, /#1e6b34/);
+  assert.doesNotMatch(svg, /ACTIVE/);
+});
+
+test("renderInflight: ready + count>0 renders ACTIVE in red", () => {
+  const svg = renderInflight({ modelName: "Qwen3.8-27B-NVFP4", state: "ready", count: 2, offline: false, pulse: false });
+  assert.match(svg, /ACTIVE/);
+  assert.match(svg, /#8b2626/);
+});
+
+test("renderInflight: pulse toggles opacity while active", () => {
+  const a = renderInflight({ modelName: "A", state: "ready", count: 1, offline: false, pulse: false });
+  const b = renderInflight({ modelName: "A", state: "ready", count: 1, offline: false, pulse: true });
+  assert.notEqual(a, b);
+  assert.match(b, /opacity="0.55"/);
+});
+
+test("renderInflight: offline and no-model states", () => {
+  const offline = renderInflight({ modelName: "A", state: "ready", count: 0, offline: true, pulse: false });
+  assert.match(offline, /OFFLINE/);
+  const noModel = renderInflight({ modelName: "unset", state: undefined, count: 0, offline: false, pulse: false });
+  assert.match(noModel, /NO MODEL/);
+});
+
+test("renderInflight: loading renders LOADING in amber", () => {
+  const svg = renderInflight({ modelName: "A", state: "loading", count: 0, offline: false, pulse: false });
+  assert.match(svg, /LOADING/);
+  assert.match(svg, /#8a6d1d/);
+});
+
+test("renderGpuGraph: draws a polyline, value, and metric label", () => {
+  const svg = renderGpuGraph({
+    gpuName: "GPU 2 · RTX 5090",
+    metric: "util_percent",
+    value: 67,
+    history: [0, 20, 40, 67],
+    offline: false,
+  });
+  assert.match(svg, /<polyline/);
+  assert.match(svg, /67%/);
+  assert.match(svg, /UTIL/);
+  assert.match(svg, /GPU 2/);
+});
+
+test("renderGpuGraph: power draws a watts value", () => {
+  const svg = renderGpuGraph({
+    gpuName: "ALL GPUS",
+    metric: "power",
+    value: 1030,
+    history: [900, 1000, 1030],
+    offline: false,
+  });
+  assert.match(svg, /1030W/);
+  assert.match(svg, /PWR/);
+  assert.match(svg, /ALL GPUS/);
+});
+
+test("renderGpuGraph: offline frame", () => {
+  const svg = renderGpuGraph({ gpuName: "ALL GPUS", metric: "util_percent", value: undefined, history: [], offline: true });
+  assert.match(svg, /OFFLINE/);
+});
+
+test("renderGpuGraph: single-point history avoids divide-by-zero", () => {
+  const svg = renderGpuGraph({ gpuName: "ALL GPUS", metric: "util_percent", value: 50, history: [50], offline: false });
+  assert.match(svg, /<svg/);
+});