From 7cf985e90cda8e47a610ef70de5162d1d6e6e792 Mon Sep 17 00:00:00 2001
From: Anthony Lukach <anthonylukach@gmail.com>
Date: Mon, 3 Aug 2026 09:29:42 -0700
Subject: [PATCH] perf: cache un-hashed static assets under /img and /logo
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These are served from public/ with `public, max-age=0, must-revalidate`,
so every navigation pays a conditional-request round-trip for them. The
responses do return 304 with 0 bytes, so this was never a re-download
problem — just a latency one, which is why it's a modest win rather than
a large one.

`immutable` is not safe here: the filenames are not content-hashed, so a
redeploy has to be able to replace them in place. An hour of freshness
plus a week of stale-while-revalidate drops the round-trip while bounding
how long a replaced asset can linger.

Extends headers() to apply in prod, which previously returned no rules at
all; the noindex rule stays non-prod only. Tests updated to match.

Refs #471
---
 next.config.js      | 18 +++++++++++++++++-
 next.config.test.ts | 41 +++++++++++++++++++++++++++--------------
 2 files changed, 44 insertions(+), 15 deletions(-)

diff --git a/next.config.js b/next.config.js
index f23eb2c6..7bcc16c3 100644
--- a/next.config.js
+++ b/next.config.js
@@ -25,10 +25,26 @@ const nextConfig = {
   transpilePackages: ["jose"],
   serverExternalPackages: ["@duckdb/node-api"],
   async headers() {
+    // ponytail: un-hashed filenames under public/, so `immutable` is unsafe —
+    // a redeploy has to be able to replace these in place. An hour of freshness
+    // drops the per-navigation revalidation round-trip without stranding a
+    // stale asset for long.
+    const staticAssets = [
+      {
+        source: "/:dir(img|logo)/:path*",
+        headers: [
+          {
+            key: "Cache-Control",
+            value: "public, max-age=3600, stale-while-revalidate=604800",
+          },
+        ],
+      },
+    ];
     if (process.env.STAGE === "prod") {
-      return [];
+      return staticAssets;
     }
     return [
+      ...staticAssets,
       {
         source: "/:path*",
         headers: [
diff --git a/next.config.test.ts b/next.config.test.ts
index f6ae8a34..5e5de366 100644
--- a/next.config.test.ts
+++ b/next.config.test.ts
@@ -1,5 +1,20 @@
 import nextConfig from "./next.config.js";
 
+const STATIC_ASSET_RULE = {
+  source: "/:dir(img|logo)/:path*",
+  headers: [
+    {
+      key: "Cache-Control",
+      value: "public, max-age=3600, stale-while-revalidate=604800",
+    },
+  ],
+};
+
+const NOINDEX_RULE = {
+  source: "/:path*",
+  headers: [{ key: "X-Robots-Tag", value: "noindex, nofollow" }],
+};
+
 describe("next.config headers()", () => {
   const originalStage = process.env.STAGE;
 
@@ -14,28 +29,26 @@ describe("next.config headers()", () => {
   test("non-prod stage emits noindex header on all paths", async () => {
     process.env.STAGE = "dev";
     const result = await nextConfig.headers!();
-    expect(result).toEqual([
-      {
-        source: "/:path*",
-        headers: [{ key: "X-Robots-Tag", value: "noindex, nofollow" }],
-      },
-    ]);
+    expect(result).toEqual([STATIC_ASSET_RULE, NOINDEX_RULE]);
   });
 
-  test("prod stage emits no header overrides", async () => {
+  test("prod stage emits no noindex override", async () => {
     process.env.STAGE = "prod";
     const result = await nextConfig.headers!();
-    expect(result).toEqual([]);
+    expect(result).toEqual([STATIC_ASSET_RULE]);
   });
 
   test("missing STAGE defaults to noindex", async () => {
     delete process.env.STAGE;
     const result = await nextConfig.headers!();
-    expect(result).toEqual([
-      {
-        source: "/:path*",
-        headers: [{ key: "X-Robots-Tag", value: "noindex, nofollow" }],
-      },
-    ]);
+    expect(result).toEqual([STATIC_ASSET_RULE, NOINDEX_RULE]);
+  });
+
+  test("static assets stay cacheable in every stage", async () => {
+    for (const stage of ["prod", "dev"]) {
+      process.env.STAGE = stage;
+      const result = await nextConfig.headers!();
+      expect(result).toContainEqual(STATIC_ASSET_RULE);
+    }
   });
 });