Fix stale static SPA fallback html

Co-Authored-By: Paperclip <noreply@paperclip.ing>

server/src/__tests__/static-index-html.test.ts

@@ -0,0 +1,49 @@
+import fs from "node:fs";
+import os from "node:os";
+import path from "node:path";
+import express from "express";
+import request from "supertest";
+import { afterEach, describe, expect, it } from "vitest";
+import { readBrandedStaticIndexHtml } from "../static-index-html.js";
+
+describe("static SPA fallback HTML", () => {
+  const tempDirs: string[] = [];
+
+  afterEach(() => {
+    for (const dir of tempDirs.splice(0)) {
+      fs.rmSync(dir, { recursive: true, force: true });
+    }
+  });
+
+  it("serves the current index.html instead of reusing stale asset hashes", async () => {
+    const tempDir = fs.mkdtempSync(path.join(os.tmpdir(), "paperclip-static-index-"));
+    tempDirs.push(tempDir);
+    const indexPath = path.join(tempDir, "index.html");
+    const app = express();
+    app.get(/.*/, (_req, res) => {
+      res
+        .status(200)
+        .set("Content-Type", "text/html")
+        .set("Cache-Control", "no-cache")
+        .end(readBrandedStaticIndexHtml(tempDir));
+    });
+
+    fs.writeFileSync(
+      indexPath,
+      '<html><body><script type="module" src="/assets/index-old.js"></script></body></html>',
+      "utf8",
+    );
+    await expect(request(app).get("/PAP/issues/PAP-9939")).resolves.toMatchObject({
+      text: expect.stringContaining("/assets/index-old.js"),
+    });
+
+    fs.writeFileSync(
+      indexPath,
+      '<html><body><script type="module" src="/assets/index-new.js"></script></body></html>',
+      "utf8",
+    );
+    const res = await request(app).get("/PAP/issues/PAP-9939");
+    expect(res.text).toContain("/assets/index-new.js");
+    expect(res.text).not.toContain("/assets/index-old.js");
+  });
+});

server/src/app.ts

@@ -41,6 +41,7 @@ import { accessRoutes } from "./routes/access.js";
 import { pluginRoutes } from "./routes/plugins.js";
 import { adapterRoutes } from "./routes/adapters.js";
 import { pluginUiStaticRoutes } from "./routes/plugin-ui-static.js";
+import { readBrandedStaticIndexHtml } from "./static-index-html.js";
 import { applyUiBranding } from "./ui-branding.js";
 import { logger } from "./middleware/logger.js";
 import { DEFAULT_LOCAL_PLUGIN_DIR, pluginLoader } from "./services/plugin-loader.js";
@@ -328,7 +329,6 @@ export async function createApp(
     ];
     const uiDist = candidates.find((p) => fs.existsSync(path.join(p, "index.html")));
     if (uiDist) {
-      const indexHtml = applyUiBranding(fs.readFileSync(path.join(uiDist, "index.html"), "utf-8"));
       // Hashed asset files (Vite emits them under /assets/<name>.<hash>.<ext>)
       // never change once built, so they can be cached aggressively.
       app.use(
@@ -368,7 +368,7 @@ export async function createApp(
           .status(200)
           .set("Content-Type", "text/html")
           .set("Cache-Control", "no-cache")
-          .end(indexHtml);
+          .end(readBrandedStaticIndexHtml(uiDist));
       });
     } else {
       console.warn("[paperclip] UI dist not found; running in API-only mode");

server/src/static-index-html.ts

@@ -0,0 +1,7 @@
+import fs from "node:fs";
+import path from "node:path";
+import { applyUiBranding } from "./ui-branding.js";
+
+export function readBrandedStaticIndexHtml(uiDist: string): string {
+  return applyUiBranding(fs.readFileSync(path.join(uiDist, "index.html"), "utf-8"));
+}