diff --git a/backend/app/main.py b/backend/app/main.py
index f93d143..ff43765 100644
--- a/backend/app/main.py
+++ b/backend/app/main.py
@@ -3,9 +3,9 @@ import json
 from datetime import datetime, timezone
 
 import httpx
-from fastapi import FastAPI
+from fastapi import FastAPI, HTTPException, Query
 from fastapi.middleware.cors import CORSMiddleware
-from fastapi.responses import StreamingResponse
+from fastapi.responses import Response, StreamingResponse
 from pydantic import BaseModel
 
 from .analysis import classify_posts, derive_factions
@@ -52,6 +52,23 @@ async def list_models():
     return {"models": ids, "default": DEFAULT_MODEL}
 
 
+@app.get("/api/avatar")
+async def avatar(url: str = Query(...)):
+    """Same-origin avatar proxy: cdn.bsky.app sends no CORS headers, which
+    blocks WebGL texture loads in the graph."""
+    if not url.startswith("https://cdn.bsky.app/"):
+        raise HTTPException(400, "only cdn.bsky.app URLs are proxied")
+    async with httpx.AsyncClient(timeout=30) as client:
+        r = await client.get(url)
+    if r.status_code != 200:
+        raise HTTPException(r.status_code, "upstream error")
+    return Response(
+        content=r.content,
+        media_type=r.headers.get("content-type", "image/jpeg"),
+        headers={"Cache-Control": "public, max-age=86400"},
+    )
+
+
 @app.post("/api/analyze")
 async def analyze(req: AnalyzeRequest):
     queue: asyncio.Queue = asyncio.Queue()
diff --git a/flake.nix b/flake.nix
index 76618b4..6034810 100644
--- a/flake.nix
+++ b/flake.nix
@@ -22,6 +22,11 @@
             UV_PYTHON_DOWNLOADS = "never";
           };
         };
+        # Headless UI screenshots (frontend/scripts/ui-shots.mjs): chromium's
+        # SwiftShader provides software WebGL for sigma.
+        ui-test = pkgs.mkShell {
+          packages = with pkgs; [ nodejs_22 chromium ];
+        };
       });
     };
 }
diff --git a/frontend/scripts/ui-shots.mjs b/frontend/scripts/ui-shots.mjs
index de359b2..127a856 100644
--- a/frontend/scripts/ui-shots.mjs
+++ b/frontend/scripts/ui-shots.mjs
@@ -12,10 +12,15 @@ const OUT = "/tmp/fray-shots";
 import { mkdirSync } from "node:fs";
 mkdirSync(OUT, { recursive: true });
 
+// Run inside `nix develop ..#ui-test` so chromium is on PATH; SwiftShader
+// provides software WebGL so sigma renders headlessly.
+import { execSync } from "node:child_process";
+const CHROMIUM =
+  process.env.FRAY_CHROMIUM ?? execSync("which chromium").toString().trim();
 const browser = await puppeteer.launch({
-  browser: "firefox",
-  executablePath: "/run/current-system/sw/bin/firefox",
+  executablePath: CHROMIUM,
   headless: true,
+  args: ["--no-sandbox", "--disable-gpu", "--enable-unsafe-swiftshader", "--use-gl=angle", "--use-angle=swiftshader"],
   defaultViewport: { width: 1440, height: 900 },
 });
 const page = await browser.newPage();
@@ -57,11 +62,16 @@ try {
   await sleep(800);
   await page.screenshot({ path: `${OUT}/4-radial-dark.png` });
 
-  // Click the root node (center of the graph container)
+  // Click a node: project graph coordinates of a mid-thread node via sigma.
   const rect = await page.evaluate(() => {
-    const el = document.querySelector(".graph-container");
-    const r = el.getBoundingClientRect();
-    return { x: r.x + r.width / 2, y: r.y + r.height / 2 };
+    const sigma = window.__fraySigma;
+    const graph = sigma.getGraph();
+    const nodes = graph.nodes();
+    const node = nodes[Math.floor(nodes.length / 3)];
+    const attrs = graph.getNodeAttributes(node);
+    const p = sigma.graphToViewport({ x: attrs.x, y: attrs.y });
+    const r = sigma.getContainer().getBoundingClientRect();
+    return { x: r.x + p.x, y: r.y + p.y };
   });
   await page.mouse.click(rect.x, rect.y);
   await sleep(1000);
diff --git a/frontend/src/GraphView.tsx b/frontend/src/GraphView.tsx
index 7d18989..a9f4b77 100644
--- a/frontend/src/GraphView.tsx
+++ b/frontend/src/GraphView.tsx
@@ -1,4 +1,3 @@
-import { createNodeImageProgram } from "@sigma/node-image";
 import type Graph from "graphology";
 import { useEffect, useMemo, useRef } from "react";
 import Sigma from "sigma";
@@ -71,14 +70,23 @@ export default function GraphView(props: Props) {
 
   const stateRef = useRef<ReducerState>(null as any);
   stateRef.current = { mode, path, hiddenFactions, highlightFaction, factionsById, selectedUri };
+  const layoutRef = useRef(layout);
+  layoutRef.current = layout;
 
   useEffect(() => {
-    const graph = buildGraph(result);
-    graphRef.current = graph;
+    let disposed = false;
+    // Dynamic import: @sigma/node-image probes WebGL at module scope, which
+    // would crash the whole app at load in browsers without WebGL.
+    void (async () => {
+      const { createNodeImageProgram } = await import("@sigma/node-image");
+      if (disposed || !containerRef.current) return;
+      const graph = buildGraph(result);
+      graphRef.current = graph;
+      applyLayout(graph, layoutRef.current, false);
 
-    const sigma = new Sigma(graph, containerRef.current!, {
+      const sigma = new Sigma(graph, containerRef.current, {
       nodeProgramClasses: {
-        image: createNodeImageProgram({ drawingMode: "background", padding: 0.15 }),
+        image: createNodeImageProgram({ drawingMode: "background", padding: 0.22 }),
       },
       defaultNodeType: "image",
       labelSize: 11,
@@ -133,21 +141,26 @@ export default function GraphView(props: Props) {
         }
         return res;
       },
-    });
-    sigma.on("clickNode", ({ node }) => onSelectRef.current(node));
-    sigma.on("clickStage", () => onSelectRef.current(null));
-    sigmaRef.current = sigma;
+      });
+      sigma.on("clickNode", ({ node }) => onSelectRef.current(node));
+      sigma.on("clickStage", () => onSelectRef.current(null));
+      sigma.setSetting("labelColor", { color: CHROME[stateRef.current.mode].inkPrimary });
+      sigma.setSetting("defaultDrawNodeHover", makeHoverDrawer(stateRef.current.mode) as any);
+      sigmaRef.current = sigma;
+      (window as any).__fraySigma = sigma; // headless UI-test hook
+    })();
     return () => {
-      sigma.kill();
+      disposed = true;
+      sigmaRef.current?.kill();
       sigmaRef.current = null;
       graphRef.current = null;
     };
   }, [result]);
 
-  // Layout switching (also positions the freshly built graph).
+  // Layout switching.
   useEffect(() => {
     if (graphRef.current) applyLayout(graphRef.current, layout);
-  }, [layout, result]);
+  }, [layout]);
 
   // Theme-dependent sigma settings.
   useEffect(() => {
diff --git a/frontend/src/graph.ts b/frontend/src/graph.ts
index 389ed64..3f08b98 100644
--- a/frontend/src/graph.ts
+++ b/frontend/src/graph.ts
@@ -11,7 +11,8 @@ export function buildGraph(result: AnalyzeResult): Graph {
       label: "@" + p.author.handle,
       faction: p.faction,
       size: p.parent_uri === null ? 18 : Math.min(13, 5 + 1.6 * Math.log2(1 + p.likeCount)),
-      image: p.author.avatar ?? undefined,
+      // Proxied through the backend: WebGL textures need CORS/same-origin.
+      image: p.author.avatar ? `/api/avatar?url=${encodeURIComponent(p.author.avatar)}` : undefined,
       type: "image",
       x: 0,
       y: 0,