diff --git a/src/lib/imager-upstream.ts b/src/lib/imager-upstream.ts
index 321a1c58..fecf5a6c 100644
--- a/src/lib/imager-upstream.ts
+++ b/src/lib/imager-upstream.ts
@@ -133,13 +133,11 @@ export async function fetchAvatarImage(
 		buildFallbackParams(params),
 		FALLBACK_TIMEOUT_MS,
 	);
+	// Deliberately not cached: a fallback render drops the effect and is only a
+	// degraded stand-in, so persisting it would keep serving the worse image
+	// for the whole cache lifetime. The local renderer caches its own renders,
+	// so the next request for this figure is cheap and returns the real one.
 	if (fallbackResult) {
-		await writeImagingCache(
-			avatarCacheDir(),
-			cacheKey,
-			fallbackResult.body,
-			fallbackResult.contentType,
-		);
 		return { ...fallbackResult, source: "fallback" };
 	}
 
diff --git a/src/lib/imager.test.ts b/src/lib/imager.test.ts
index af763267..e99ad5fd 100644
--- a/src/lib/imager.test.ts
+++ b/src/lib/imager.test.ts
@@ -1,7 +1,14 @@
 // @ts-nocheck
+import { mkdtempSync, readdirSync, rmSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import { getAvatarUrl } from "./imager";
-import { FALLBACK_TIMEOUT_MS, PRIMARY_TIMEOUT_MS } from "./imager-upstream";
+import {
+	FALLBACK_TIMEOUT_MS,
+	fetchAvatarImage,
+	PRIMARY_TIMEOUT_MS,
+} from "./imager-upstream";
 
 afterEach(() => {
 	vi.unstubAllEnvs();
@@ -73,3 +80,65 @@ describe("upstream render budgets", () => {
 		expect(FALLBACK_TIMEOUT_MS).toBeLessThan(PRIMARY_TIMEOUT_MS);
 	});
 });
+
+describe("fetchAvatarImage caching", () => {
+	let cacheRoot = "";
+
+	beforeEach(() => {
+		cacheRoot = mkdtempSync(join(tmpdir(), "imager-cache-"));
+		vi.stubEnv("IMAGING_CACHE_ROOT", cacheRoot);
+		vi.stubEnv("IMAGER_URL", "http://primary.invalid/avatarimage");
+		vi.stubEnv("IMAGING_UPSTREAM_URL", "http://primary.invalid/avatarimage");
+		vi.stubEnv("APP_URL", "https://cms.example");
+	});
+
+	afterEach(() => {
+		vi.unstubAllGlobals();
+		rmSync(cacheRoot, { recursive: true, force: true });
+	});
+
+	const params = () =>
+		new URLSearchParams({
+			figure: "hd-180-1",
+			direction: "2",
+			head_direction: "3",
+			size: "m",
+			img_format: "png",
+		});
+
+	it("persists renders from the primary renderer", async () => {
+		vi.stubGlobal(
+			"fetch",
+			vi.fn(
+				async () =>
+					new Response(new Uint8Array([1, 2, 3]), {
+						headers: { "content-type": "image/png" },
+					}),
+			),
+		);
+
+		const first = await fetchAvatarImage("https://cms.example", params());
+		expect(first.source).toBe("primary");
+		expect(readdirSync(join(cacheRoot, "avatars")).length).toBe(2);
+
+		const second = await fetchAvatarImage("https://cms.example", params());
+		expect(second.source).toBe("cache");
+	});
+
+	it("never persists a fallback render", async () => {
+		vi.stubGlobal(
+			"fetch",
+			vi.fn(async (url: string | URL) =>
+				String(url).includes("primary.invalid")
+					? new Response(null, { status: 500 })
+					: new Response(new Uint8Array([4, 5, 6]), {
+							headers: { "content-type": "image/png" },
+						}),
+			),
+		);
+
+		const result = await fetchAvatarImage("https://cms.example", params());
+		expect(result.source).toBe("fallback");
+		expect(() => readdirSync(join(cacheRoot, "avatars"))).toThrow();
+	});
+});