Compress and cache packaged web assets#4516

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Compress and cache packaged web assets #4516

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93bcde9
Compress and cache packaged web assets
yashranaway Jul 25, 2026
c31c1aa
Compress the SPA fallback and share in-flight compressions
yashranaway Jul 25, 2026
4c66786
Key the SPA fallback compression by content
yashranaway Jul 25, 2026
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86 changes: 82 additions & 4 deletions apps/server/src/http.ts
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -37,6 +37,13 @@ import {
} from "./auth/http.ts";
import * as ServerEnvironment from "./environment/ServerEnvironment.ts";
import { browserApiCorsAllowedHeaders, browserApiCorsAllowedMethods } from "./httpCors.ts";
import {
contentCacheKey,
isCompressibleContentType,
makeStaticCompressionCache,
negotiateStaticEncoding,
resolveStaticCacheControl,
} from "./staticAssetDelivery.ts";

const OTLP_TRACES_PROXY_PATH = "/api/observability/v1/traces";
const LOOPBACK_HOSTNAMES = new Set(["127.0.0.1", "::1", "localhost"]);
Expand DownExpand Up@@ -204,6 +211,8 @@ export const assetRouteLayer = HttpRouter.add(
}),
);

const staticCompressionCache = makeStaticCompressionCache();

export const staticAndDevRouteLayer = HttpRouter.add(
"GET",
"*",
Expand DownExpand Up@@ -273,9 +282,18 @@ export const staticAndDevRouteLayer = HttpRouter.add(
if (!indexData) {
return HttpServerResponse.text("Not Found", { status: 404 });
}
return HttpServerResponse.uint8Array(indexData, {
status: 200,
return yield* respondWithStaticFile({
data: indexData,
contentType: "text/html; charset=utf-8",
// The SPA fallback always revalidates so a new build is picked up.
cacheControl: resolveStaticCacheControl("index.html"),
// Every deep link lands here, so the document is worth compressing.
// This is the one path whose file keeps a stable name across builds,
// so it is keyed by content: metadata read separately from the bytes
// could describe a different build than the one being served. The
// document is small enough for hashing it to be cheap.
cacheKey: contentCacheKey(indexData),
acceptEncoding: request.headers["accept-encoding"],
});
}

Expand All@@ -285,9 +303,69 @@ export const staticAndDevRouteLayer = HttpRouter.add(
return HttpServerResponse.text("Internal Server Error", { status: 500 });
}

return HttpServerResponse.uint8Array(data, {
status: 200,
return yield* respondWithStaticFile({
data,
contentType,
cacheControl: resolveStaticCacheControl(staticRelativePath),
cacheKey: staticCacheKey(filePath, fileInfo),
acceptEncoding: request.headers["accept-encoding"],
});
}),
);

/**
* Identifies a build of a file for the compression cache, without hashing
* payloads that can run to megabytes. The stat is taken before the bytes are
* read, so a rebuild landing between the two can only orphan an entry under
* the superseded key, never publish those bytes under the newer one. Files
* whose contents change without their name are keyed by content instead; the
* rest carry a content hash in their filename already.
*/
function staticCacheKey(filePath: string, info: FileSystem.File.Info): string {
const mtimeMs = info.mtime.pipe(
Option.map((mtime) => mtime.getTime()),
Option.getOrElse(() => 0),
);
return `${filePath} ${mtimeMs} ${info.size}`;
}

const respondWithStaticFile = Effect.fn("staticAndDevRoute.respond")(function* (input: {
readonly data: Uint8Array;
readonly contentType: string;
readonly cacheControl: string;
/** Null for the SPA fallback, whose bytes are re-read on every request. */
readonly cacheKey: string | null;
readonly acceptEncoding: string | undefined;
}) {
const headers: Record<string, string> = {
"Cache-Control": input.cacheControl,
};

const encoding = isCompressibleContentType(input.contentType)
? negotiateStaticEncoding(input.acceptEncoding)
: null;
if (isCompressibleContentType(input.contentType)) {
// Announce negotiation even when this client took the identity encoding,
// so shared caches do not hand a compressed body to a client that
// cannot read it.
headers["Vary"] = "Accept-Encoding";
}

const cacheKey = input.cacheKey;
const compressed =
encoding && cacheKey !== null
? yield* Effect.tryPromise(() =>
staticCompressionCache.get({ cacheKey, data: input.data, encoding }),
).pipe(Effect.orElseSucceed(() => null))
: null;

if (compressed && encoding) {
headers["Content-Encoding"] = encoding;
}

return HttpServerResponse.uint8Array(compressed ?? input.data, {
status: 200,
contentType: input.contentType,
headers,
});
});
223 changes: 223 additions & 0 deletions apps/server/src/staticAssetDelivery.test.ts
View file
Open in desktop
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,223 @@
import { describe, expect, it } from "vite-plus/test";

import {
contentCacheKey,
isCompressibleContentType,
makeStaticCompressionCache,
negotiateStaticEncoding,
resolveStaticCacheControl,
} from "./staticAssetDelivery.ts";

describe("contentCacheKey", () => {
const encode = (value: string) => new TextEncoder().encode(value);

it("keys identical content the same way", () => {
expect(contentCacheKey(encode("<html>a</html>"))).toBe(
contentCacheKey(encode("<html>a</html>")),
);
});

it("separates content of the same length", () => {
// A rebuild can reuse a filename, a size, and even a timestamp, so the
// key has to come from the bytes themselves.
expect(contentCacheKey(encode("<html>a</html>"))).not.toBe(
contentCacheKey(encode("<html>b</html>")),
);
});
});

describe("resolveStaticCacheControl", () => {
it("marks content-hashed bundle assets immutable", () => {
expect(resolveStaticCacheControl("assets/index-DxV9k2Qp.js")).toBe(
"public, max-age=31536000, immutable",
);
expect(resolveStaticCacheControl("assets/style-a1b2c3d4.css")).toBe(
"public, max-age=31536000, immutable",
);
});

it("revalidates entry documents and unhashed files", () => {
expect(resolveStaticCacheControl("index.html")).toBe("no-cache");
expect(resolveStaticCacheControl("/index.html")).toBe("no-cache");
// No hash means a rebuild reuses the name, so it must not be pinned.
expect(resolveStaticCacheControl("assets/logo.svg")).toBe("no-cache");
expect(resolveStaticCacheControl("favicon.ico")).toBe("no-cache");
});
});

describe("negotiateStaticEncoding", () => {
it("prefers brotli when the client accepts both", () => {
expect(negotiateStaticEncoding("gzip, deflate, br")).toBe("br");
});

it("falls back to gzip when brotli is absent", () => {
expect(negotiateStaticEncoding("gzip, deflate")).toBe("gzip");
});

it("returns null when nothing usable is offered", () => {
expect(negotiateStaticEncoding(undefined)).toBeNull();
expect(negotiateStaticEncoding("")).toBeNull();
expect(negotiateStaticEncoding("deflate")).toBeNull();
});

it("honors explicit refusals expressed as q=0", () => {
expect(negotiateStaticEncoding("br;q=0, gzip")).toBe("gzip");
expect(negotiateStaticEncoding("gzip;q=0, br;q=0")).toBeNull();
});

it("accepts a wildcard offer", () => {
expect(negotiateStaticEncoding("*")).toBe("br");
});
});

describe("isCompressibleContentType", () => {
it("compresses text and structured payloads", () => {
expect(isCompressibleContentType("text/html; charset=utf-8")).toBe(true);
expect(isCompressibleContentType("application/javascript")).toBe(true);
expect(isCompressibleContentType("image/svg+xml")).toBe(true);
});

it("leaves already-compressed binaries alone", () => {
expect(isCompressibleContentType("image/png")).toBe(false);
expect(isCompressibleContentType("font/woff2")).toBe(false);
expect(isCompressibleContentType("application/octet-stream")).toBe(false);
});
});

describe("makeStaticCompressionCache", () => {
const bundle = new TextEncoder().encode("export const value = 1;\n".repeat(500));

it("compresses a payload once and reuses the result", async () => {
let compressCalls = 0;
const cache = makeStaticCompressionCache(async (data) => {
compressCalls += 1;
return data.subarray(0, 64);
});

const first = await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" });
const second = await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" });

expect(first).not.toBeNull();
expect(second).toBe(first);
expect(compressCalls).toBe(1);
});

it("compresses once for a burst of concurrent requests", async () => {
let compressCalls = 0;
let release = () => {};
const started = new Promise<void>((resolve) => {
release = resolve;
});
const cache = makeStaticCompressionCache(async (data) => {
compressCalls += 1;
await started;
return data.subarray(0, 64);
});

const requests = [
cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" }),
cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" }),
cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" }),
];
release();
const results = await Promise.all(requests);

expect(compressCalls).toBe(1);
expect(results[1]).toBe(results[0]);
expect(results[2]).toBe(results[0]);
});

it("retries after a failed compression instead of caching the failure", async () => {
let compressCalls = 0;
const cache = makeStaticCompressionCache(async (data) => {
compressCalls += 1;
if (compressCalls === 1) throw new Error("zlib buffer error");
return data.subarray(0, 64);
});

await expect(
cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" }),
).rejects.toThrow("zlib buffer error");

const retried = await cache.get({
cacheKey: "bundle.js 1 100",
data: bundle,
encoding: "gzip",
});

expect(compressCalls).toBe(2);
expect(retried).not.toBeNull();
});

it("recompresses when the file changes underneath the same path", async () => {
let compressCalls = 0;
const cache = makeStaticCompressionCache(async (data) => {
compressCalls += 1;
return data.subarray(0, 64);
});

await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" });
await cache.get({ cacheKey: "bundle.js 2 140", data: bundle, encoding: "gzip" });

expect(compressCalls).toBe(2);
});

it("keeps brotli and gzip results apart", async () => {
const cache = makeStaticCompressionCache(async (data, encoding) =>
new TextEncoder().encode(`${encoding}:${data.byteLength}`),
);

const brotli = await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" });
const gzipped = await cache.get({
cacheKey: "bundle.js 1 100",
data: bundle,
encoding: "gzip",
});

expect(new TextDecoder().decode(brotli ?? new Uint8Array())).toContain("br:");
expect(new TextDecoder().decode(gzipped ?? new Uint8Array())).toContain("gzip:");
});

it("skips payloads too small to be worth compressing", async () => {
let compressCalls = 0;
const cache = makeStaticCompressionCache(async (data) => {
compressCalls += 1;
return data;
});

const result = await cache.get({
cacheKey: "tiny.js 1 8",
data: new TextEncoder().encode("const a=1;"),
encoding: "gzip",
});

expect(result).toBeNull();
expect(compressCalls).toBe(0);
});

it("declines a result that did not get smaller", async () => {
const cache = makeStaticCompressionCache(async (data) => new Uint8Array(data.byteLength + 32));

const result = await cache.get({
cacheKey: "incompressible.bin 1 100",
data: bundle,
encoding: "gzip",
});

expect(result).toBeNull();
expect(cache.retainedByteLength).toBe(0);
});

it("really shrinks a realistic bundle with the default compressor", async () => {
const cache = makeStaticCompressionCache();

const compressed = await cache.get({
cacheKey: "real.js 1 100",
data: bundle,
encoding: "br",
});

expect(compressed).not.toBeNull();
expect((compressed as Uint8Array).byteLength).toBeLessThan(bundle.byteLength / 2);
});
});
Loading
Loading
, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Add copy buttons to all 
 blocks\n(function() {\n function addCopyButtons() {\n document.querySelectorAll('pre code').forEach(function(codeBlock) {\n if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;\n codeBlock.parentElement.setAttribute('data-copy-added', 'true');\n \n var btn = document.createElement('button');\n btn.textContent = 'Copy';\n btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';\n btn.onmouseover = function() { this.style.opacity = '1'; };\n btn.onmouseout = function() { this.style.opacity = '0.7'; };\n btn.onclick = function() {\n navigator.clipboard.writeText(codeBlock.textContent).then(function() {\n btn.textContent = 'Copied!';\n setTimeout(function() { btn.textContent = 'Copy'; }, 1500);\n });\n };\n codeBlock.parentElement.style.position = 'relative';\n codeBlock.parentElement.appendChild(btn);\n });\n }\n \n addCopyButtons();\n \n // Re-run on dynamic content\n var observer = new MutationObserver(addCopyButtons);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Add Copy Buttons to Code Blocks");
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '

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Compress and cache packaged web assets#4516

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to your account

 Open

yashranaway
wants to merge
3
commits into

base:main
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+490

−4

 Open


Compress and cache packaged web assets
#4516
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93bcde9

Compress and cache packaged web assets


yashranaway Jul 25, 2026
c31c1aa

Compress the SPA fallback and share in-flight compressions


yashranaway Jul 25, 2026
4c66786

Key the SPA fallback compression by content


yashranaway Jul 25, 2026

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86 changes: 82 additions & 4 deletions
apps/server/src/http.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -37,6 +37,13 @@ import {
} from "./auth/http.ts";
import * as ServerEnvironment from "./environment/ServerEnvironment.ts";
import { browserApiCorsAllowedHeaders, browserApiCorsAllowedMethods } from "./httpCors.ts";
import {
 contentCacheKey,
 isCompressibleContentType,
 makeStaticCompressionCache,
 negotiateStaticEncoding,
 resolveStaticCacheControl,
} from "./staticAssetDelivery.ts";

const OTLP_TRACES_PROXY_PATH = "/api/observability/v1/traces";
const LOOPBACK_HOSTNAMES = new Set(["127.0.0.1", "::1", "localhost"]);
Expand DownExpand Up@@ -204,6 +211,8 @@ export const assetRouteLayer = HttpRouter.add(
 }),
);

const staticCompressionCache = makeStaticCompressionCache();

export const staticAndDevRouteLayer = HttpRouter.add(
 "GET",
 "*",
Expand DownExpand Up@@ -273,9 +282,18 @@ export const staticAndDevRouteLayer = HttpRouter.add(
 if (!indexData) {
 return HttpServerResponse.text("Not Found", { status: 404 });
 }
 return HttpServerResponse.uint8Array(indexData, {
status: 200,
 return yield* respondWithStaticFile({
data: indexData,
 contentType: "text/html; charset=utf-8",
 // The SPA fallback always revalidates so a new build is picked up.
 cacheControl: resolveStaticCacheControl("index.html"),
 // Every deep link lands here, so the document is worth compressing.
 // This is the one path whose file keeps a stable name across builds,
 // so it is keyed by content: metadata read separately from the bytes
 // could describe a different build than the one being served. The
 // document is small enough for hashing it to be cheap.
 cacheKey: contentCacheKey(indexData),
 acceptEncoding: request.headers["accept-encoding"],
 });
 }

Expand All@@ -285,9 +303,69 @@ export const staticAndDevRouteLayer = HttpRouter.add(
 return HttpServerResponse.text("Internal Server Error", { status: 500 });
 }

 return HttpServerResponse.uint8Array(data, {
status: 200,
 return yield* respondWithStaticFile({
data,
 contentType,
 cacheControl: resolveStaticCacheControl(staticRelativePath),
 cacheKey: staticCacheKey(filePath, fileInfo),
 acceptEncoding: request.headers["accept-encoding"],
 });
 }),
);

/**
 * Identifies a build of a file for the compression cache, without hashing
 * payloads that can run to megabytes. The stat is taken before the bytes are
 * read, so a rebuild landing between the two can only orphan an entry under
 * the superseded key, never publish those bytes under the newer one. Files
 * whose contents change without their name are keyed by content instead; the
 * rest carry a content hash in their filename already.
 */
function staticCacheKey(filePath: string, info: FileSystem.File.Info): string {
 const mtimeMs = info.mtime.pipe(
 Option.map((mtime) => mtime.getTime()),
 Option.getOrElse(() => 0),
 );
 return `${filePath} ${mtimeMs} ${info.size}`;
}

const respondWithStaticFile = Effect.fn("staticAndDevRoute.respond")(function* (input: {
 readonly data: Uint8Array;
 readonly contentType: string;
 readonly cacheControl: string;
 /** Null for the SPA fallback, whose bytes are re-read on every request. */
 readonly cacheKey: string | null;
 readonly acceptEncoding: string | undefined;
}) {
 const headers: Record<string, string> = {
 "Cache-Control": input.cacheControl,
 };

 const encoding = isCompressibleContentType(input.contentType)
 ? negotiateStaticEncoding(input.acceptEncoding)
 : null;
 if (isCompressibleContentType(input.contentType)) {
 // Announce negotiation even when this client took the identity encoding,
 // so shared caches do not hand a compressed body to a client that
 // cannot read it.
 headers["Vary"] = "Accept-Encoding";
 }

 const cacheKey = input.cacheKey;
 const compressed =
 encoding && cacheKey !== null
 ? yield* Effect.tryPromise(() =>
 staticCompressionCache.get({ cacheKey, data: input.data, encoding }),
 ).pipe(Effect.orElseSucceed(() => null))
 : null;

 if (compressed && encoding) {
 headers["Content-Encoding"] = encoding;
 }

 return HttpServerResponse.uint8Array(compressed ?? input.data, {
 status: 200,
 contentType: input.contentType,
 headers,
 });
});

223 changes: 223 additions & 0 deletions
apps/server/src/staticAssetDelivery.test.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,223 @@
import { describe, expect, it } from "vite-plus/test";

import {
 contentCacheKey,
 isCompressibleContentType,
 makeStaticCompressionCache,
 negotiateStaticEncoding,
 resolveStaticCacheControl,
} from "./staticAssetDelivery.ts";

describe("contentCacheKey", () => {
 const encode = (value: string) => new TextEncoder().encode(value);

 it("keys identical content the same way", () => {
 expect(contentCacheKey(encode("<html>a</html>"))).toBe(
 contentCacheKey(encode("<html>a</html>")),
 );
 });

 it("separates content of the same length", () => {
 // A rebuild can reuse a filename, a size, and even a timestamp, so the
 // key has to come from the bytes themselves.
 expect(contentCacheKey(encode("<html>a</html>"))).not.toBe(
 contentCacheKey(encode("<html>b</html>")),
 );
 });
});

describe("resolveStaticCacheControl", () => {
 it("marks content-hashed bundle assets immutable", () => {
 expect(resolveStaticCacheControl("assets/index-DxV9k2Qp.js")).toBe(
 "public, max-age=31536000, immutable",
 );
 expect(resolveStaticCacheControl("assets/style-a1b2c3d4.css")).toBe(
 "public, max-age=31536000, immutable",
 );
 });

 it("revalidates entry documents and unhashed files", () => {
 expect(resolveStaticCacheControl("index.html")).toBe("no-cache");
 expect(resolveStaticCacheControl("/index.html")).toBe("no-cache");
 // No hash means a rebuild reuses the name, so it must not be pinned.
 expect(resolveStaticCacheControl("assets/logo.svg")).toBe("no-cache");
 expect(resolveStaticCacheControl("favicon.ico")).toBe("no-cache");
 });
});

describe("negotiateStaticEncoding", () => {
 it("prefers brotli when the client accepts both", () => {
 expect(negotiateStaticEncoding("gzip, deflate, br")).toBe("br");
 });

 it("falls back to gzip when brotli is absent", () => {
 expect(negotiateStaticEncoding("gzip, deflate")).toBe("gzip");
 });

 it("returns null when nothing usable is offered", () => {
 expect(negotiateStaticEncoding(undefined)).toBeNull();
 expect(negotiateStaticEncoding("")).toBeNull();
 expect(negotiateStaticEncoding("deflate")).toBeNull();
 });

 it("honors explicit refusals expressed as q=0", () => {
 expect(negotiateStaticEncoding("br;q=0, gzip")).toBe("gzip");
 expect(negotiateStaticEncoding("gzip;q=0, br;q=0")).toBeNull();
 });

 it("accepts a wildcard offer", () => {
 expect(negotiateStaticEncoding("*")).toBe("br");
 });
});

describe("isCompressibleContentType", () => {
 it("compresses text and structured payloads", () => {
 expect(isCompressibleContentType("text/html; charset=utf-8")).toBe(true);
 expect(isCompressibleContentType("application/javascript")).toBe(true);
 expect(isCompressibleContentType("image/svg+xml")).toBe(true);
 });

 it("leaves already-compressed binaries alone", () => {
 expect(isCompressibleContentType("image/png")).toBe(false);
 expect(isCompressibleContentType("font/woff2")).toBe(false);
 expect(isCompressibleContentType("application/octet-stream")).toBe(false);
 });
});

describe("makeStaticCompressionCache", () => {
 const bundle = new TextEncoder().encode("export const value = 1;\n".repeat(500));

 it("compresses a payload once and reuses the result", async () => {
 let compressCalls = 0;
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 return data.subarray(0, 64);
 });

 const first = await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" });
 const second = await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" });

 expect(first).not.toBeNull();
 expect(second).toBe(first);
 expect(compressCalls).toBe(1);
 });

 it("compresses once for a burst of concurrent requests", async () => {
 let compressCalls = 0;
 let release = () => {};
 const started = new Promise<void>((resolve) => {
 release = resolve;
 });
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 await started;
 return data.subarray(0, 64);
 });

 const requests = [
 cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" }),
 cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" }),
 cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" }),
 ];
 release();
 const results = await Promise.all(requests);

 expect(compressCalls).toBe(1);
 expect(results[1]).toBe(results[0]);
 expect(results[2]).toBe(results[0]);
 });

 it("retries after a failed compression instead of caching the failure", async () => {
 let compressCalls = 0;
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 if (compressCalls === 1) throw new Error("zlib buffer error");
 return data.subarray(0, 64);
 });

 await expect(
 cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" }),
 ).rejects.toThrow("zlib buffer error");

 const retried = await cache.get({
 cacheKey: "bundle.js 1 100",
 data: bundle,
 encoding: "gzip",
 });

 expect(compressCalls).toBe(2);
 expect(retried).not.toBeNull();
 });

 it("recompresses when the file changes underneath the same path", async () => {
 let compressCalls = 0;
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 return data.subarray(0, 64);
 });

 await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" });
 await cache.get({ cacheKey: "bundle.js 2 140", data: bundle, encoding: "gzip" });

 expect(compressCalls).toBe(2);
 });

 it("keeps brotli and gzip results apart", async () => {
 const cache = makeStaticCompressionCache(async (data, encoding) =>
 new TextEncoder().encode(`${encoding}:${data.byteLength}`),
 );

 const brotli = await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" });
 const gzipped = await cache.get({
 cacheKey: "bundle.js 1 100",
 data: bundle,
 encoding: "gzip",
 });

 expect(new TextDecoder().decode(brotli ?? new Uint8Array())).toContain("br:");
 expect(new TextDecoder().decode(gzipped ?? new Uint8Array())).toContain("gzip:");
 });

 it("skips payloads too small to be worth compressing", async () => {
 let compressCalls = 0;
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 return data;
 });

 const result = await cache.get({
 cacheKey: "tiny.js 1 8",
 data: new TextEncoder().encode("const a=1;"),
 encoding: "gzip",
 });

 expect(result).toBeNull();
 expect(compressCalls).toBe(0);
 });

 it("declines a result that did not get smaller", async () => {
 const cache = makeStaticCompressionCache(async (data) => new Uint8Array(data.byteLength + 32));

 const result = await cache.get({
 cacheKey: "incompressible.bin 1 100",
 data: bundle,
 encoding: "gzip",
 });

 expect(result).toBeNull();
 expect(cache.retainedByteLength).toBe(0);
 });

 it("really shrinks a realistic bundle with the default compressor", async () => {
 const cache = makeStaticCompressionCache();

 const compressed = await cache.get({
 cacheKey: "real.js 1 100",
 data: bundle,
 encoding: "br",
 });

 expect(compressed).not.toBeNull();
 expect((compressed as Uint8Array).byteLength).toBeLessThan(bundle.byteLength / 2);
 });
});
Loading
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Force GitHub README to respect dark mode\n(function() {\n var style = document.createElement('style');\n style.textContent = '\n .markdown-body {\n color-scheme: dark light;\n }\n .markdown-body pre { background: #161b22 !important; }\n .markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }\n .markdown-body table th, .markdown-body table td { border-color: #30363d !important; }\n .markdown-body img { background: #0d1117; }\n .markdown-body blockquote { border-left-color: #8b949e; }\n .markdown-body hr { border-color: #30363d; }\n ';\n document.head.appendChild(style);\n})();", "GitHub Dark Mode README Fix");
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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Compress and cache packaged web assets#4516

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yashranaway
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Compress and cache packaged web assets
#4516
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93bcde9

Compress and cache packaged web assets


yashranaway Jul 25, 2026
c31c1aa

Compress the SPA fallback and share in-flight compressions


yashranaway Jul 25, 2026
4c66786

Key the SPA fallback compression by content


yashranaway Jul 25, 2026

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86 changes: 82 additions & 4 deletions
apps/server/src/http.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -37,6 +37,13 @@ import {
} from "./auth/http.ts";
import * as ServerEnvironment from "./environment/ServerEnvironment.ts";
import { browserApiCorsAllowedHeaders, browserApiCorsAllowedMethods } from "./httpCors.ts";
import {
 contentCacheKey,
 isCompressibleContentType,
 makeStaticCompressionCache,
 negotiateStaticEncoding,
 resolveStaticCacheControl,
} from "./staticAssetDelivery.ts";

const OTLP_TRACES_PROXY_PATH = "/api/observability/v1/traces";
const LOOPBACK_HOSTNAMES = new Set(["127.0.0.1", "::1", "localhost"]);
Expand DownExpand Up@@ -204,6 +211,8 @@ export const assetRouteLayer = HttpRouter.add(
 }),
);

const staticCompressionCache = makeStaticCompressionCache();

export const staticAndDevRouteLayer = HttpRouter.add(
 "GET",
 "*",
Expand DownExpand Up@@ -273,9 +282,18 @@ export const staticAndDevRouteLayer = HttpRouter.add(
 if (!indexData) {
 return HttpServerResponse.text("Not Found", { status: 404 });
 }
 return HttpServerResponse.uint8Array(indexData, {
status: 200,
 return yield* respondWithStaticFile({
data: indexData,
 contentType: "text/html; charset=utf-8",
 // The SPA fallback always revalidates so a new build is picked up.
 cacheControl: resolveStaticCacheControl("index.html"),
 // Every deep link lands here, so the document is worth compressing.
 // This is the one path whose file keeps a stable name across builds,
 // so it is keyed by content: metadata read separately from the bytes
 // could describe a different build than the one being served. The
 // document is small enough for hashing it to be cheap.
 cacheKey: contentCacheKey(indexData),
 acceptEncoding: request.headers["accept-encoding"],
 });
 }

Expand All@@ -285,9 +303,69 @@ export const staticAndDevRouteLayer = HttpRouter.add(
 return HttpServerResponse.text("Internal Server Error", { status: 500 });
 }

 return HttpServerResponse.uint8Array(data, {
status: 200,
 return yield* respondWithStaticFile({
data,
 contentType,
 cacheControl: resolveStaticCacheControl(staticRelativePath),
 cacheKey: staticCacheKey(filePath, fileInfo),
 acceptEncoding: request.headers["accept-encoding"],
 });
 }),
);

/**
 * Identifies a build of a file for the compression cache, without hashing
 * payloads that can run to megabytes. The stat is taken before the bytes are
 * read, so a rebuild landing between the two can only orphan an entry under
 * the superseded key, never publish those bytes under the newer one. Files
 * whose contents change without their name are keyed by content instead; the
 * rest carry a content hash in their filename already.
 */
function staticCacheKey(filePath: string, info: FileSystem.File.Info): string {
 const mtimeMs = info.mtime.pipe(
 Option.map((mtime) => mtime.getTime()),
 Option.getOrElse(() => 0),
 );
 return `${filePath} ${mtimeMs} ${info.size}`;
}

const respondWithStaticFile = Effect.fn("staticAndDevRoute.respond")(function* (input: {
 readonly data: Uint8Array;
 readonly contentType: string;
 readonly cacheControl: string;
 /** Null for the SPA fallback, whose bytes are re-read on every request. */
 readonly cacheKey: string | null;
 readonly acceptEncoding: string | undefined;
}) {
 const headers: Record<string, string> = {
 "Cache-Control": input.cacheControl,
 };

 const encoding = isCompressibleContentType(input.contentType)
 ? negotiateStaticEncoding(input.acceptEncoding)
 : null;
 if (isCompressibleContentType(input.contentType)) {
 // Announce negotiation even when this client took the identity encoding,
 // so shared caches do not hand a compressed body to a client that
 // cannot read it.
 headers["Vary"] = "Accept-Encoding";
 }

 const cacheKey = input.cacheKey;
 const compressed =
 encoding && cacheKey !== null
 ? yield* Effect.tryPromise(() =>
 staticCompressionCache.get({ cacheKey, data: input.data, encoding }),
 ).pipe(Effect.orElseSucceed(() => null))
 : null;

 if (compressed && encoding) {
 headers["Content-Encoding"] = encoding;
 }

 return HttpServerResponse.uint8Array(compressed ?? input.data, {
 status: 200,
 contentType: input.contentType,
 headers,
 });
});

223 changes: 223 additions & 0 deletions
apps/server/src/staticAssetDelivery.test.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,223 @@
import { describe, expect, it } from "vite-plus/test";

import {
 contentCacheKey,
 isCompressibleContentType,
 makeStaticCompressionCache,
 negotiateStaticEncoding,
 resolveStaticCacheControl,
} from "./staticAssetDelivery.ts";

describe("contentCacheKey", () => {
 const encode = (value: string) => new TextEncoder().encode(value);

 it("keys identical content the same way", () => {
 expect(contentCacheKey(encode("<html>a</html>"))).toBe(
 contentCacheKey(encode("<html>a</html>")),
 );
 });

 it("separates content of the same length", () => {
 // A rebuild can reuse a filename, a size, and even a timestamp, so the
 // key has to come from the bytes themselves.
 expect(contentCacheKey(encode("<html>a</html>"))).not.toBe(
 contentCacheKey(encode("<html>b</html>")),
 );
 });
});

describe("resolveStaticCacheControl", () => {
 it("marks content-hashed bundle assets immutable", () => {
 expect(resolveStaticCacheControl("assets/index-DxV9k2Qp.js")).toBe(
 "public, max-age=31536000, immutable",
 );
 expect(resolveStaticCacheControl("assets/style-a1b2c3d4.css")).toBe(
 "public, max-age=31536000, immutable",
 );
 });

 it("revalidates entry documents and unhashed files", () => {
 expect(resolveStaticCacheControl("index.html")).toBe("no-cache");
 expect(resolveStaticCacheControl("/index.html")).toBe("no-cache");
 // No hash means a rebuild reuses the name, so it must not be pinned.
 expect(resolveStaticCacheControl("assets/logo.svg")).toBe("no-cache");
 expect(resolveStaticCacheControl("favicon.ico")).toBe("no-cache");
 });
});

describe("negotiateStaticEncoding", () => {
 it("prefers brotli when the client accepts both", () => {
 expect(negotiateStaticEncoding("gzip, deflate, br")).toBe("br");
 });

 it("falls back to gzip when brotli is absent", () => {
 expect(negotiateStaticEncoding("gzip, deflate")).toBe("gzip");
 });

 it("returns null when nothing usable is offered", () => {
 expect(negotiateStaticEncoding(undefined)).toBeNull();
 expect(negotiateStaticEncoding("")).toBeNull();
 expect(negotiateStaticEncoding("deflate")).toBeNull();
 });

 it("honors explicit refusals expressed as q=0", () => {
 expect(negotiateStaticEncoding("br;q=0, gzip")).toBe("gzip");
 expect(negotiateStaticEncoding("gzip;q=0, br;q=0")).toBeNull();
 });

 it("accepts a wildcard offer", () => {
 expect(negotiateStaticEncoding("*")).toBe("br");
 });
});

describe("isCompressibleContentType", () => {
 it("compresses text and structured payloads", () => {
 expect(isCompressibleContentType("text/html; charset=utf-8")).toBe(true);
 expect(isCompressibleContentType("application/javascript")).toBe(true);
 expect(isCompressibleContentType("image/svg+xml")).toBe(true);
 });

 it("leaves already-compressed binaries alone", () => {
 expect(isCompressibleContentType("image/png")).toBe(false);
 expect(isCompressibleContentType("font/woff2")).toBe(false);
 expect(isCompressibleContentType("application/octet-stream")).toBe(false);
 });
});

describe("makeStaticCompressionCache", () => {
 const bundle = new TextEncoder().encode("export const value = 1;\n".repeat(500));

 it("compresses a payload once and reuses the result", async () => {
 let compressCalls = 0;
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 return data.subarray(0, 64);
 });

 const first = await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" });
 const second = await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" });

 expect(first).not.toBeNull();
 expect(second).toBe(first);
 expect(compressCalls).toBe(1);
 });

 it("compresses once for a burst of concurrent requests", async () => {
 let compressCalls = 0;
 let release = () => {};
 const started = new Promise<void>((resolve) => {
 release = resolve;
 });
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 await started;
 return data.subarray(0, 64);
 });

 const requests = [
 cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" }),
 cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" }),
 cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" }),
 ];
 release();
 const results = await Promise.all(requests);

 expect(compressCalls).toBe(1);
 expect(results[1]).toBe(results[0]);
 expect(results[2]).toBe(results[0]);
 });

 it("retries after a failed compression instead of caching the failure", async () => {
 let compressCalls = 0;
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 if (compressCalls === 1) throw new Error("zlib buffer error");
 return data.subarray(0, 64);
 });

 await expect(
 cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" }),
 ).rejects.toThrow("zlib buffer error");

 const retried = await cache.get({
 cacheKey: "bundle.js 1 100",
 data: bundle,
 encoding: "gzip",
 });

 expect(compressCalls).toBe(2);
 expect(retried).not.toBeNull();
 });

 it("recompresses when the file changes underneath the same path", async () => {
 let compressCalls = 0;
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 return data.subarray(0, 64);
 });

 await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" });
 await cache.get({ cacheKey: "bundle.js 2 140", data: bundle, encoding: "gzip" });

 expect(compressCalls).toBe(2);
 });

 it("keeps brotli and gzip results apart", async () => {
 const cache = makeStaticCompressionCache(async (data, encoding) =>
 new TextEncoder().encode(`${encoding}:${data.byteLength}`),
 );

 const brotli = await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" });
 const gzipped = await cache.get({
 cacheKey: "bundle.js 1 100",
 data: bundle,
 encoding: "gzip",
 });

 expect(new TextDecoder().decode(brotli ?? new Uint8Array())).toContain("br:");
 expect(new TextDecoder().decode(gzipped ?? new Uint8Array())).toContain("gzip:");
 });

 it("skips payloads too small to be worth compressing", async () => {
 let compressCalls = 0;
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 return data;
 });

 const result = await cache.get({
 cacheKey: "tiny.js 1 8",
 data: new TextEncoder().encode("const a=1;"),
 encoding: "gzip",
 });

 expect(result).toBeNull();
 expect(compressCalls).toBe(0);
 });

 it("declines a result that did not get smaller", async () => {
 const cache = makeStaticCompressionCache(async (data) => new Uint8Array(data.byteLength + 32));

 const result = await cache.get({
 cacheKey: "incompressible.bin 1 100",
 data: bundle,
 encoding: "gzip",
 });

 expect(result).toBeNull();
 expect(cache.retainedByteLength).toBe(0);
 });

 it("really shrinks a realistic bundle with the default compressor", async () => {
 const cache = makeStaticCompressionCache();

 const compressed = await cache.get({
 cacheKey: "real.js 1 100",
 data: bundle,
 encoding: "br",
 });

 expect(compressed).not.toBeNull();
 expect((compressed as Uint8Array).byteLength).toBeLessThan(bundle.byteLength / 2);
 });
});
Loading
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Highlight search terms from Google/DuckDuckGo/Bing referrer\n(function() {\n var ref = document.referrer;\n var terms = [];\n \n if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {\n var url = new URL(ref);\n var q = url.searchParams.get('q') || url.searchParams.get('p');\n if (q) {\n terms = q.split(/\\s+/).filter(function(t) { return t.length > 2; });\n }\n }\n \n if (terms.length === 0) return;\n \n var style = document.createElement('style');\n style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';\n document.head.appendChild(style);\n \n function highlight(node) {\n if (node.nodeType === 3) { // text node\n var text = node.textContent;\n var found = false;\n terms.forEach(function(term) {\n var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\\]\\\\]/g, '\\\\') + ')', 'gi');\n if (regex.test(text)) {\n found = true;\n var frag = document.createDocumentFragment();\n var parts = text.split(regex);\n parts.forEach(function(part, i) {\n if (i % 2 === 0) {\n frag.appendChild(document.createTextNode(part));\n } else {\n var span = document.createElement('span');\n span.className = 'userscript-highlight';\n span.textContent = part;\n frag.appendChild(span);\n }\n });\n node.parentNode.replaceChild(frag, node);\n }\n });\n } else if (node.nodeType === 1 && node.childNodes) { // element\n var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];\n if (!skipTags.includes(node.tagName)) {\n Array.from(node.childNodes).forEach(highlight);\n }\n }\n }\n \n highlight(document.body);\n \n // Re-highlight on dynamic content\n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1 || node.nodeType === 3) highlight(node);\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Highlight Search Terms");
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
Compress and cache packaged web assets#4516

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to your account

 Open

yashranaway
wants to merge
3
commits into

base:main
Choose a base branch

from


+490

−4

 Open


Compress and cache packaged web assets
#4516
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93bcde9

Compress and cache packaged web assets


yashranaway Jul 25, 2026
c31c1aa

Compress the SPA fallback and share in-flight compressions


yashranaway Jul 25, 2026
4c66786

Key the SPA fallback compression by content


yashranaway Jul 25, 2026

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86 changes: 82 additions & 4 deletions
apps/server/src/http.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -37,6 +37,13 @@ import {
} from "./auth/http.ts";
import * as ServerEnvironment from "./environment/ServerEnvironment.ts";
import { browserApiCorsAllowedHeaders, browserApiCorsAllowedMethods } from "./httpCors.ts";
import {
 contentCacheKey,
 isCompressibleContentType,
 makeStaticCompressionCache,
 negotiateStaticEncoding,
 resolveStaticCacheControl,
} from "./staticAssetDelivery.ts";

const OTLP_TRACES_PROXY_PATH = "/api/observability/v1/traces";
const LOOPBACK_HOSTNAMES = new Set(["127.0.0.1", "::1", "localhost"]);
Expand DownExpand Up@@ -204,6 +211,8 @@ export const assetRouteLayer = HttpRouter.add(
 }),
);

const staticCompressionCache = makeStaticCompressionCache();

export const staticAndDevRouteLayer = HttpRouter.add(
 "GET",
 "*",
Expand DownExpand Up@@ -273,9 +282,18 @@ export const staticAndDevRouteLayer = HttpRouter.add(
 if (!indexData) {
 return HttpServerResponse.text("Not Found", { status: 404 });
 }
 return HttpServerResponse.uint8Array(indexData, {
status: 200,
 return yield* respondWithStaticFile({
data: indexData,
 contentType: "text/html; charset=utf-8",
 // The SPA fallback always revalidates so a new build is picked up.
 cacheControl: resolveStaticCacheControl("index.html"),
 // Every deep link lands here, so the document is worth compressing.
 // This is the one path whose file keeps a stable name across builds,
 // so it is keyed by content: metadata read separately from the bytes
 // could describe a different build than the one being served. The
 // document is small enough for hashing it to be cheap.
 cacheKey: contentCacheKey(indexData),
 acceptEncoding: request.headers["accept-encoding"],
 });
 }

Expand All@@ -285,9 +303,69 @@ export const staticAndDevRouteLayer = HttpRouter.add(
 return HttpServerResponse.text("Internal Server Error", { status: 500 });
 }

 return HttpServerResponse.uint8Array(data, {
status: 200,
 return yield* respondWithStaticFile({
data,
 contentType,
 cacheControl: resolveStaticCacheControl(staticRelativePath),
 cacheKey: staticCacheKey(filePath, fileInfo),
 acceptEncoding: request.headers["accept-encoding"],
 });
 }),
);

/**
 * Identifies a build of a file for the compression cache, without hashing
 * payloads that can run to megabytes. The stat is taken before the bytes are
 * read, so a rebuild landing between the two can only orphan an entry under
 * the superseded key, never publish those bytes under the newer one. Files
 * whose contents change without their name are keyed by content instead; the
 * rest carry a content hash in their filename already.
 */
function staticCacheKey(filePath: string, info: FileSystem.File.Info): string {
 const mtimeMs = info.mtime.pipe(
 Option.map((mtime) => mtime.getTime()),
 Option.getOrElse(() => 0),
 );
 return `${filePath} ${mtimeMs} ${info.size}`;
}

const respondWithStaticFile = Effect.fn("staticAndDevRoute.respond")(function* (input: {
 readonly data: Uint8Array;
 readonly contentType: string;
 readonly cacheControl: string;
 /** Null for the SPA fallback, whose bytes are re-read on every request. */
 readonly cacheKey: string | null;
 readonly acceptEncoding: string | undefined;
}) {
 const headers: Record<string, string> = {
 "Cache-Control": input.cacheControl,
 };

 const encoding = isCompressibleContentType(input.contentType)
 ? negotiateStaticEncoding(input.acceptEncoding)
 : null;
 if (isCompressibleContentType(input.contentType)) {
 // Announce negotiation even when this client took the identity encoding,
 // so shared caches do not hand a compressed body to a client that
 // cannot read it.
 headers["Vary"] = "Accept-Encoding";
 }

 const cacheKey = input.cacheKey;
 const compressed =
 encoding && cacheKey !== null
 ? yield* Effect.tryPromise(() =>
 staticCompressionCache.get({ cacheKey, data: input.data, encoding }),
 ).pipe(Effect.orElseSucceed(() => null))
 : null;

 if (compressed && encoding) {
 headers["Content-Encoding"] = encoding;
 }

 return HttpServerResponse.uint8Array(compressed ?? input.data, {
 status: 200,
 contentType: input.contentType,
 headers,
 });
});

223 changes: 223 additions & 0 deletions
apps/server/src/staticAssetDelivery.test.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,223 @@
import { describe, expect, it } from "vite-plus/test";

import {
 contentCacheKey,
 isCompressibleContentType,
 makeStaticCompressionCache,
 negotiateStaticEncoding,
 resolveStaticCacheControl,
} from "./staticAssetDelivery.ts";

describe("contentCacheKey", () => {
 const encode = (value: string) => new TextEncoder().encode(value);

 it("keys identical content the same way", () => {
 expect(contentCacheKey(encode("<html>a</html>"))).toBe(
 contentCacheKey(encode("<html>a</html>")),
 );
 });

 it("separates content of the same length", () => {
 // A rebuild can reuse a filename, a size, and even a timestamp, so the
 // key has to come from the bytes themselves.
 expect(contentCacheKey(encode("<html>a</html>"))).not.toBe(
 contentCacheKey(encode("<html>b</html>")),
 );
 });
});

describe("resolveStaticCacheControl", () => {
 it("marks content-hashed bundle assets immutable", () => {
 expect(resolveStaticCacheControl("assets/index-DxV9k2Qp.js")).toBe(
 "public, max-age=31536000, immutable",
 );
 expect(resolveStaticCacheControl("assets/style-a1b2c3d4.css")).toBe(
 "public, max-age=31536000, immutable",
 );
 });

 it("revalidates entry documents and unhashed files", () => {
 expect(resolveStaticCacheControl("index.html")).toBe("no-cache");
 expect(resolveStaticCacheControl("/index.html")).toBe("no-cache");
 // No hash means a rebuild reuses the name, so it must not be pinned.
 expect(resolveStaticCacheControl("assets/logo.svg")).toBe("no-cache");
 expect(resolveStaticCacheControl("favicon.ico")).toBe("no-cache");
 });
});

describe("negotiateStaticEncoding", () => {
 it("prefers brotli when the client accepts both", () => {
 expect(negotiateStaticEncoding("gzip, deflate, br")).toBe("br");
 });

 it("falls back to gzip when brotli is absent", () => {
 expect(negotiateStaticEncoding("gzip, deflate")).toBe("gzip");
 });

 it("returns null when nothing usable is offered", () => {
 expect(negotiateStaticEncoding(undefined)).toBeNull();
 expect(negotiateStaticEncoding("")).toBeNull();
 expect(negotiateStaticEncoding("deflate")).toBeNull();
 });

 it("honors explicit refusals expressed as q=0", () => {
 expect(negotiateStaticEncoding("br;q=0, gzip")).toBe("gzip");
 expect(negotiateStaticEncoding("gzip;q=0, br;q=0")).toBeNull();
 });

 it("accepts a wildcard offer", () => {
 expect(negotiateStaticEncoding("*")).toBe("br");
 });
});

describe("isCompressibleContentType", () => {
 it("compresses text and structured payloads", () => {
 expect(isCompressibleContentType("text/html; charset=utf-8")).toBe(true);
 expect(isCompressibleContentType("application/javascript")).toBe(true);
 expect(isCompressibleContentType("image/svg+xml")).toBe(true);
 });

 it("leaves already-compressed binaries alone", () => {
 expect(isCompressibleContentType("image/png")).toBe(false);
 expect(isCompressibleContentType("font/woff2")).toBe(false);
 expect(isCompressibleContentType("application/octet-stream")).toBe(false);
 });
});

describe("makeStaticCompressionCache", () => {
 const bundle = new TextEncoder().encode("export const value = 1;\n".repeat(500));

 it("compresses a payload once and reuses the result", async () => {
 let compressCalls = 0;
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 return data.subarray(0, 64);
 });

 const first = await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" });
 const second = await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" });

 expect(first).not.toBeNull();
 expect(second).toBe(first);
 expect(compressCalls).toBe(1);
 });

 it("compresses once for a burst of concurrent requests", async () => {
 let compressCalls = 0;
 let release = () => {};
 const started = new Promise<void>((resolve) => {
 release = resolve;
 });
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 await started;
 return data.subarray(0, 64);
 });

 const requests = [
 cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" }),
 cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" }),
 cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" }),
 ];
 release();
 const results = await Promise.all(requests);

 expect(compressCalls).toBe(1);
 expect(results[1]).toBe(results[0]);
 expect(results[2]).toBe(results[0]);
 });

 it("retries after a failed compression instead of caching the failure", async () => {
 let compressCalls = 0;
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 if (compressCalls === 1) throw new Error("zlib buffer error");
 return data.subarray(0, 64);
 });

 await expect(
 cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" }),
 ).rejects.toThrow("zlib buffer error");

 const retried = await cache.get({
 cacheKey: "bundle.js 1 100",
 data: bundle,
 encoding: "gzip",
 });

 expect(compressCalls).toBe(2);
 expect(retried).not.toBeNull();
 });

 it("recompresses when the file changes underneath the same path", async () => {
 let compressCalls = 0;
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 return data.subarray(0, 64);
 });

 await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" });
 await cache.get({ cacheKey: "bundle.js 2 140", data: bundle, encoding: "gzip" });

 expect(compressCalls).toBe(2);
 });

 it("keeps brotli and gzip results apart", async () => {
 const cache = makeStaticCompressionCache(async (data, encoding) =>
 new TextEncoder().encode(`${encoding}:${data.byteLength}`),
 );

 const brotli = await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" });
 const gzipped = await cache.get({
 cacheKey: "bundle.js 1 100",
 data: bundle,
 encoding: "gzip",
 });

 expect(new TextDecoder().decode(brotli ?? new Uint8Array())).toContain("br:");
 expect(new TextDecoder().decode(gzipped ?? new Uint8Array())).toContain("gzip:");
 });

 it("skips payloads too small to be worth compressing", async () => {
 let compressCalls = 0;
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 return data;
 });

 const result = await cache.get({
 cacheKey: "tiny.js 1 8",
 data: new TextEncoder().encode("const a=1;"),
 encoding: "gzip",
 });

 expect(result).toBeNull();
 expect(compressCalls).toBe(0);
 });

 it("declines a result that did not get smaller", async () => {
 const cache = makeStaticCompressionCache(async (data) => new Uint8Array(data.byteLength + 32));

 const result = await cache.get({
 cacheKey: "incompressible.bin 1 100",
 data: bundle,
 encoding: "gzip",
 });

 expect(result).toBeNull();
 expect(cache.retainedByteLength).toBe(0);
 });

 it("really shrinks a realistic bundle with the default compressor", async () => {
 const cache = makeStaticCompressionCache();

 const compressed = await cache.get({
 cacheKey: "real.js 1 100",
 data: bundle,
 encoding: "br",
 });

 expect(compressed).not.toBeNull();
 expect((compressed as Uint8Array).byteLength).toBeLessThan(bundle.byteLength / 2);
 });
});
Loading
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Strip utm_, fbclid, gclid, etc. from all links on page\n(function() {\n var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',\n 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',\n 'ref', 'ref_src', 'source', 'medium', 'campaign'];\n \n function cleanUrl(url) {\n try {\n var u = new URL(url, window.location.origin);\n var changed = false;\n trackingParams.forEach(function(p) {\n if (u.searchParams.has(p)) {\n u.searchParams.delete(p);\n changed = true;\n }\n });\n return changed ? u.toString() : url;\n } catch (e) {\n return url;\n }\n }\n \n function cleanLinks() {\n document.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n \n cleanLinks();\n \n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1) {\n if (node.tagName === 'A') cleanLinks();\n node.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Remove Tracking Parameters from Links");
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '

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Compress and cache packaged web assets#4516

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Compress and cache packaged web assets
#4516
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93bcde9

Compress and cache packaged web assets


yashranaway Jul 25, 2026
c31c1aa

Compress the SPA fallback and share in-flight compressions


yashranaway Jul 25, 2026
4c66786

Key the SPA fallback compression by content


yashranaway Jul 25, 2026

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86 changes: 82 additions & 4 deletions
apps/server/src/http.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -37,6 +37,13 @@ import {
} from "./auth/http.ts";
import * as ServerEnvironment from "./environment/ServerEnvironment.ts";
import { browserApiCorsAllowedHeaders, browserApiCorsAllowedMethods } from "./httpCors.ts";
import {
 contentCacheKey,
 isCompressibleContentType,
 makeStaticCompressionCache,
 negotiateStaticEncoding,
 resolveStaticCacheControl,
} from "./staticAssetDelivery.ts";

const OTLP_TRACES_PROXY_PATH = "/api/observability/v1/traces";
const LOOPBACK_HOSTNAMES = new Set(["127.0.0.1", "::1", "localhost"]);
Expand DownExpand Up@@ -204,6 +211,8 @@ export const assetRouteLayer = HttpRouter.add(
 }),
);

const staticCompressionCache = makeStaticCompressionCache();

export const staticAndDevRouteLayer = HttpRouter.add(
 "GET",
 "*",
Expand DownExpand Up@@ -273,9 +282,18 @@ export const staticAndDevRouteLayer = HttpRouter.add(
 if (!indexData) {
 return HttpServerResponse.text("Not Found", { status: 404 });
 }
 return HttpServerResponse.uint8Array(indexData, {
status: 200,
 return yield* respondWithStaticFile({
data: indexData,
 contentType: "text/html; charset=utf-8",
 // The SPA fallback always revalidates so a new build is picked up.
 cacheControl: resolveStaticCacheControl("index.html"),
 // Every deep link lands here, so the document is worth compressing.
 // This is the one path whose file keeps a stable name across builds,
 // so it is keyed by content: metadata read separately from the bytes
 // could describe a different build than the one being served. The
 // document is small enough for hashing it to be cheap.
 cacheKey: contentCacheKey(indexData),
 acceptEncoding: request.headers["accept-encoding"],
 });
 }

Expand All@@ -285,9 +303,69 @@ export const staticAndDevRouteLayer = HttpRouter.add(
 return HttpServerResponse.text("Internal Server Error", { status: 500 });
 }

 return HttpServerResponse.uint8Array(data, {
status: 200,
 return yield* respondWithStaticFile({
data,
 contentType,
 cacheControl: resolveStaticCacheControl(staticRelativePath),
 cacheKey: staticCacheKey(filePath, fileInfo),
 acceptEncoding: request.headers["accept-encoding"],
 });
 }),
);

/**
 * Identifies a build of a file for the compression cache, without hashing
 * payloads that can run to megabytes. The stat is taken before the bytes are
 * read, so a rebuild landing between the two can only orphan an entry under
 * the superseded key, never publish those bytes under the newer one. Files
 * whose contents change without their name are keyed by content instead; the
 * rest carry a content hash in their filename already.
 */
function staticCacheKey(filePath: string, info: FileSystem.File.Info): string {
 const mtimeMs = info.mtime.pipe(
 Option.map((mtime) => mtime.getTime()),
 Option.getOrElse(() => 0),
 );
 return `${filePath} ${mtimeMs} ${info.size}`;
}

const respondWithStaticFile = Effect.fn("staticAndDevRoute.respond")(function* (input: {
 readonly data: Uint8Array;
 readonly contentType: string;
 readonly cacheControl: string;
 /** Null for the SPA fallback, whose bytes are re-read on every request. */
 readonly cacheKey: string | null;
 readonly acceptEncoding: string | undefined;
}) {
 const headers: Record<string, string> = {
 "Cache-Control": input.cacheControl,
 };

 const encoding = isCompressibleContentType(input.contentType)
 ? negotiateStaticEncoding(input.acceptEncoding)
 : null;
 if (isCompressibleContentType(input.contentType)) {
 // Announce negotiation even when this client took the identity encoding,
 // so shared caches do not hand a compressed body to a client that
 // cannot read it.
 headers["Vary"] = "Accept-Encoding";
 }

 const cacheKey = input.cacheKey;
 const compressed =
 encoding && cacheKey !== null
 ? yield* Effect.tryPromise(() =>
 staticCompressionCache.get({ cacheKey, data: input.data, encoding }),
 ).pipe(Effect.orElseSucceed(() => null))
 : null;

 if (compressed && encoding) {
 headers["Content-Encoding"] = encoding;
 }

 return HttpServerResponse.uint8Array(compressed ?? input.data, {
 status: 200,
 contentType: input.contentType,
 headers,
 });
});

223 changes: 223 additions & 0 deletions
apps/server/src/staticAssetDelivery.test.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,223 @@
import { describe, expect, it } from "vite-plus/test";

import {
 contentCacheKey,
 isCompressibleContentType,
 makeStaticCompressionCache,
 negotiateStaticEncoding,
 resolveStaticCacheControl,
} from "./staticAssetDelivery.ts";

describe("contentCacheKey", () => {
 const encode = (value: string) => new TextEncoder().encode(value);

 it("keys identical content the same way", () => {
 expect(contentCacheKey(encode("<html>a</html>"))).toBe(
 contentCacheKey(encode("<html>a</html>")),
 );
 });

 it("separates content of the same length", () => {
 // A rebuild can reuse a filename, a size, and even a timestamp, so the
 // key has to come from the bytes themselves.
 expect(contentCacheKey(encode("<html>a</html>"))).not.toBe(
 contentCacheKey(encode("<html>b</html>")),
 );
 });
});

describe("resolveStaticCacheControl", () => {
 it("marks content-hashed bundle assets immutable", () => {
 expect(resolveStaticCacheControl("assets/index-DxV9k2Qp.js")).toBe(
 "public, max-age=31536000, immutable",
 );
 expect(resolveStaticCacheControl("assets/style-a1b2c3d4.css")).toBe(
 "public, max-age=31536000, immutable",
 );
 });

 it("revalidates entry documents and unhashed files", () => {
 expect(resolveStaticCacheControl("index.html")).toBe("no-cache");
 expect(resolveStaticCacheControl("/index.html")).toBe("no-cache");
 // No hash means a rebuild reuses the name, so it must not be pinned.
 expect(resolveStaticCacheControl("assets/logo.svg")).toBe("no-cache");
 expect(resolveStaticCacheControl("favicon.ico")).toBe("no-cache");
 });
});

describe("negotiateStaticEncoding", () => {
 it("prefers brotli when the client accepts both", () => {
 expect(negotiateStaticEncoding("gzip, deflate, br")).toBe("br");
 });

 it("falls back to gzip when brotli is absent", () => {
 expect(negotiateStaticEncoding("gzip, deflate")).toBe("gzip");
 });

 it("returns null when nothing usable is offered", () => {
 expect(negotiateStaticEncoding(undefined)).toBeNull();
 expect(negotiateStaticEncoding("")).toBeNull();
 expect(negotiateStaticEncoding("deflate")).toBeNull();
 });

 it("honors explicit refusals expressed as q=0", () => {
 expect(negotiateStaticEncoding("br;q=0, gzip")).toBe("gzip");
 expect(negotiateStaticEncoding("gzip;q=0, br;q=0")).toBeNull();
 });

 it("accepts a wildcard offer", () => {
 expect(negotiateStaticEncoding("*")).toBe("br");
 });
});

describe("isCompressibleContentType", () => {
 it("compresses text and structured payloads", () => {
 expect(isCompressibleContentType("text/html; charset=utf-8")).toBe(true);
 expect(isCompressibleContentType("application/javascript")).toBe(true);
 expect(isCompressibleContentType("image/svg+xml")).toBe(true);
 });

 it("leaves already-compressed binaries alone", () => {
 expect(isCompressibleContentType("image/png")).toBe(false);
 expect(isCompressibleContentType("font/woff2")).toBe(false);
 expect(isCompressibleContentType("application/octet-stream")).toBe(false);
 });
});

describe("makeStaticCompressionCache", () => {
 const bundle = new TextEncoder().encode("export const value = 1;\n".repeat(500));

 it("compresses a payload once and reuses the result", async () => {
 let compressCalls = 0;
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 return data.subarray(0, 64);
 });

 const first = await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" });
 const second = await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" });

 expect(first).not.toBeNull();
 expect(second).toBe(first);
 expect(compressCalls).toBe(1);
 });

 it("compresses once for a burst of concurrent requests", async () => {
 let compressCalls = 0;
 let release = () => {};
 const started = new Promise<void>((resolve) => {
 release = resolve;
 });
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 await started;
 return data.subarray(0, 64);
 });

 const requests = [
 cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" }),
 cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" }),
 cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" }),
 ];
 release();
 const results = await Promise.all(requests);

 expect(compressCalls).toBe(1);
 expect(results[1]).toBe(results[0]);
 expect(results[2]).toBe(results[0]);
 });

 it("retries after a failed compression instead of caching the failure", async () => {
 let compressCalls = 0;
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 if (compressCalls === 1) throw new Error("zlib buffer error");
 return data.subarray(0, 64);
 });

 await expect(
 cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" }),
 ).rejects.toThrow("zlib buffer error");

 const retried = await cache.get({
 cacheKey: "bundle.js 1 100",
 data: bundle,
 encoding: "gzip",
 });

 expect(compressCalls).toBe(2);
 expect(retried).not.toBeNull();
 });

 it("recompresses when the file changes underneath the same path", async () => {
 let compressCalls = 0;
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 return data.subarray(0, 64);
 });

 await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" });
 await cache.get({ cacheKey: "bundle.js 2 140", data: bundle, encoding: "gzip" });

 expect(compressCalls).toBe(2);
 });

 it("keeps brotli and gzip results apart", async () => {
 const cache = makeStaticCompressionCache(async (data, encoding) =>
 new TextEncoder().encode(`${encoding}:${data.byteLength}`),
 );

 const brotli = await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" });
 const gzipped = await cache.get({
 cacheKey: "bundle.js 1 100",
 data: bundle,
 encoding: "gzip",
 });

 expect(new TextDecoder().decode(brotli ?? new Uint8Array())).toContain("br:");
 expect(new TextDecoder().decode(gzipped ?? new Uint8Array())).toContain("gzip:");
 });

 it("skips payloads too small to be worth compressing", async () => {
 let compressCalls = 0;
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 return data;
 });

 const result = await cache.get({
 cacheKey: "tiny.js 1 8",
 data: new TextEncoder().encode("const a=1;"),
 encoding: "gzip",
 });

 expect(result).toBeNull();
 expect(compressCalls).toBe(0);
 });

 it("declines a result that did not get smaller", async () => {
 const cache = makeStaticCompressionCache(async (data) => new Uint8Array(data.byteLength + 32));

 const result = await cache.get({
 cacheKey: "incompressible.bin 1 100",
 data: bundle,
 encoding: "gzip",
 });

 expect(result).toBeNull();
 expect(cache.retainedByteLength).toBe(0);
 });

 it("really shrinks a realistic bundle with the default compressor", async () => {
 const cache = makeStaticCompressionCache();

 const compressed = await cache.get({
 cacheKey: "real.js 1 100",
 data: bundle,
 encoding: "br",
 });

 expect(compressed).not.toBeNull();
 expect((compressed as Uint8Array).byteLength).toBeLessThan(bundle.byteLength / 2);
 });
});
Loading
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Auto-enable theater mode on YouTube\n(function() {\n function tryTheater() {\n var btn = document.querySelector('button[aria-label=\"Theater mode\"], ytd-player #player button[title=\"Theater mode\"]');\n if (btn && !btn.classList.contains('activated')) {\n btn.click();\n }\n }\n \n // Try immediately\n tryTheater();\n \n // Try after navigation (SPA)\n var lastUrl = location.href;\n setInterval(function() {\n if (location.href !== lastUrl) {\n lastUrl = location.href;\n setTimeout(tryTheater, 500);\n }\n }, 1000);\n \n // Also try on player load\n var observer = new MutationObserver(tryTheater);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "YouTube Theater Mode Default");
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
Compress and cache packaged web assets#4516

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Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

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privacy statement. We’ll occasionally send you account related emails.

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to your account

 Open

yashranaway
wants to merge
3
commits into

base:main
Choose a base branch

from


+490

−4

 Open


Compress and cache packaged web assets
#4516
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93bcde9

Compress and cache packaged web assets


yashranaway Jul 25, 2026
c31c1aa

Compress the SPA fallback and share in-flight compressions


yashranaway Jul 25, 2026
4c66786

Key the SPA fallback compression by content


yashranaway Jul 25, 2026

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Conversations

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86 changes: 82 additions & 4 deletions
apps/server/src/http.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -37,6 +37,13 @@ import {
} from "./auth/http.ts";
import * as ServerEnvironment from "./environment/ServerEnvironment.ts";
import { browserApiCorsAllowedHeaders, browserApiCorsAllowedMethods } from "./httpCors.ts";
import {
 contentCacheKey,
 isCompressibleContentType,
 makeStaticCompressionCache,
 negotiateStaticEncoding,
 resolveStaticCacheControl,
} from "./staticAssetDelivery.ts";

const OTLP_TRACES_PROXY_PATH = "/api/observability/v1/traces";
const LOOPBACK_HOSTNAMES = new Set(["127.0.0.1", "::1", "localhost"]);
Expand DownExpand Up@@ -204,6 +211,8 @@ export const assetRouteLayer = HttpRouter.add(
 }),
);

const staticCompressionCache = makeStaticCompressionCache();

export const staticAndDevRouteLayer = HttpRouter.add(
 "GET",
 "*",
Expand DownExpand Up@@ -273,9 +282,18 @@ export const staticAndDevRouteLayer = HttpRouter.add(
 if (!indexData) {
 return HttpServerResponse.text("Not Found", { status: 404 });
 }
 return HttpServerResponse.uint8Array(indexData, {
status: 200,
 return yield* respondWithStaticFile({
data: indexData,
 contentType: "text/html; charset=utf-8",
 // The SPA fallback always revalidates so a new build is picked up.
 cacheControl: resolveStaticCacheControl("index.html"),
 // Every deep link lands here, so the document is worth compressing.
 // This is the one path whose file keeps a stable name across builds,
 // so it is keyed by content: metadata read separately from the bytes
 // could describe a different build than the one being served. The
 // document is small enough for hashing it to be cheap.
 cacheKey: contentCacheKey(indexData),
 acceptEncoding: request.headers["accept-encoding"],
 });
 }

Expand All@@ -285,9 +303,69 @@ export const staticAndDevRouteLayer = HttpRouter.add(
 return HttpServerResponse.text("Internal Server Error", { status: 500 });
 }

 return HttpServerResponse.uint8Array(data, {
status: 200,
 return yield* respondWithStaticFile({
data,
 contentType,
 cacheControl: resolveStaticCacheControl(staticRelativePath),
 cacheKey: staticCacheKey(filePath, fileInfo),
 acceptEncoding: request.headers["accept-encoding"],
 });
 }),
);

/**
 * Identifies a build of a file for the compression cache, without hashing
 * payloads that can run to megabytes. The stat is taken before the bytes are
 * read, so a rebuild landing between the two can only orphan an entry under
 * the superseded key, never publish those bytes under the newer one. Files
 * whose contents change without their name are keyed by content instead; the
 * rest carry a content hash in their filename already.
 */
function staticCacheKey(filePath: string, info: FileSystem.File.Info): string {
 const mtimeMs = info.mtime.pipe(
 Option.map((mtime) => mtime.getTime()),
 Option.getOrElse(() => 0),
 );
 return `${filePath} ${mtimeMs} ${info.size}`;
}

const respondWithStaticFile = Effect.fn("staticAndDevRoute.respond")(function* (input: {
 readonly data: Uint8Array;
 readonly contentType: string;
 readonly cacheControl: string;
 /** Null for the SPA fallback, whose bytes are re-read on every request. */
 readonly cacheKey: string | null;
 readonly acceptEncoding: string | undefined;
}) {
 const headers: Record<string, string> = {
 "Cache-Control": input.cacheControl,
 };

 const encoding = isCompressibleContentType(input.contentType)
 ? negotiateStaticEncoding(input.acceptEncoding)
 : null;
 if (isCompressibleContentType(input.contentType)) {
 // Announce negotiation even when this client took the identity encoding,
 // so shared caches do not hand a compressed body to a client that
 // cannot read it.
 headers["Vary"] = "Accept-Encoding";
 }

 const cacheKey = input.cacheKey;
 const compressed =
 encoding && cacheKey !== null
 ? yield* Effect.tryPromise(() =>
 staticCompressionCache.get({ cacheKey, data: input.data, encoding }),
 ).pipe(Effect.orElseSucceed(() => null))
 : null;

 if (compressed && encoding) {
 headers["Content-Encoding"] = encoding;
 }

 return HttpServerResponse.uint8Array(compressed ?? input.data, {
 status: 200,
 contentType: input.contentType,
 headers,
 });
});

223 changes: 223 additions & 0 deletions
apps/server/src/staticAssetDelivery.test.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,223 @@
import { describe, expect, it } from "vite-plus/test";

import {
 contentCacheKey,
 isCompressibleContentType,
 makeStaticCompressionCache,
 negotiateStaticEncoding,
 resolveStaticCacheControl,
} from "./staticAssetDelivery.ts";

describe("contentCacheKey", () => {
 const encode = (value: string) => new TextEncoder().encode(value);

 it("keys identical content the same way", () => {
 expect(contentCacheKey(encode("<html>a</html>"))).toBe(
 contentCacheKey(encode("<html>a</html>")),
 );
 });

 it("separates content of the same length", () => {
 // A rebuild can reuse a filename, a size, and even a timestamp, so the
 // key has to come from the bytes themselves.
 expect(contentCacheKey(encode("<html>a</html>"))).not.toBe(
 contentCacheKey(encode("<html>b</html>")),
 );
 });
});

describe("resolveStaticCacheControl", () => {
 it("marks content-hashed bundle assets immutable", () => {
 expect(resolveStaticCacheControl("assets/index-DxV9k2Qp.js")).toBe(
 "public, max-age=31536000, immutable",
 );
 expect(resolveStaticCacheControl("assets/style-a1b2c3d4.css")).toBe(
 "public, max-age=31536000, immutable",
 );
 });

 it("revalidates entry documents and unhashed files", () => {
 expect(resolveStaticCacheControl("index.html")).toBe("no-cache");
 expect(resolveStaticCacheControl("/index.html")).toBe("no-cache");
 // No hash means a rebuild reuses the name, so it must not be pinned.
 expect(resolveStaticCacheControl("assets/logo.svg")).toBe("no-cache");
 expect(resolveStaticCacheControl("favicon.ico")).toBe("no-cache");
 });
});

describe("negotiateStaticEncoding", () => {
 it("prefers brotli when the client accepts both", () => {
 expect(negotiateStaticEncoding("gzip, deflate, br")).toBe("br");
 });

 it("falls back to gzip when brotli is absent", () => {
 expect(negotiateStaticEncoding("gzip, deflate")).toBe("gzip");
 });

 it("returns null when nothing usable is offered", () => {
 expect(negotiateStaticEncoding(undefined)).toBeNull();
 expect(negotiateStaticEncoding("")).toBeNull();
 expect(negotiateStaticEncoding("deflate")).toBeNull();
 });

 it("honors explicit refusals expressed as q=0", () => {
 expect(negotiateStaticEncoding("br;q=0, gzip")).toBe("gzip");
 expect(negotiateStaticEncoding("gzip;q=0, br;q=0")).toBeNull();
 });

 it("accepts a wildcard offer", () => {
 expect(negotiateStaticEncoding("*")).toBe("br");
 });
});

describe("isCompressibleContentType", () => {
 it("compresses text and structured payloads", () => {
 expect(isCompressibleContentType("text/html; charset=utf-8")).toBe(true);
 expect(isCompressibleContentType("application/javascript")).toBe(true);
 expect(isCompressibleContentType("image/svg+xml")).toBe(true);
 });

 it("leaves already-compressed binaries alone", () => {
 expect(isCompressibleContentType("image/png")).toBe(false);
 expect(isCompressibleContentType("font/woff2")).toBe(false);
 expect(isCompressibleContentType("application/octet-stream")).toBe(false);
 });
});

describe("makeStaticCompressionCache", () => {
 const bundle = new TextEncoder().encode("export const value = 1;\n".repeat(500));

 it("compresses a payload once and reuses the result", async () => {
 let compressCalls = 0;
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 return data.subarray(0, 64);
 });

 const first = await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" });
 const second = await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" });

 expect(first).not.toBeNull();
 expect(second).toBe(first);
 expect(compressCalls).toBe(1);
 });

 it("compresses once for a burst of concurrent requests", async () => {
 let compressCalls = 0;
 let release = () => {};
 const started = new Promise<void>((resolve) => {
 release = resolve;
 });
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 await started;
 return data.subarray(0, 64);
 });

 const requests = [
 cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" }),
 cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" }),
 cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" }),
 ];
 release();
 const results = await Promise.all(requests);

 expect(compressCalls).toBe(1);
 expect(results[1]).toBe(results[0]);
 expect(results[2]).toBe(results[0]);
 });

 it("retries after a failed compression instead of caching the failure", async () => {
 let compressCalls = 0;
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 if (compressCalls === 1) throw new Error("zlib buffer error");
 return data.subarray(0, 64);
 });

 await expect(
 cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" }),
 ).rejects.toThrow("zlib buffer error");

 const retried = await cache.get({
 cacheKey: "bundle.js 1 100",
 data: bundle,
 encoding: "gzip",
 });

 expect(compressCalls).toBe(2);
 expect(retried).not.toBeNull();
 });

 it("recompresses when the file changes underneath the same path", async () => {
 let compressCalls = 0;
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 return data.subarray(0, 64);
 });

 await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" });
 await cache.get({ cacheKey: "bundle.js 2 140", data: bundle, encoding: "gzip" });

 expect(compressCalls).toBe(2);
 });

 it("keeps brotli and gzip results apart", async () => {
 const cache = makeStaticCompressionCache(async (data, encoding) =>
 new TextEncoder().encode(`${encoding}:${data.byteLength}`),
 );

 const brotli = await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" });
 const gzipped = await cache.get({
 cacheKey: "bundle.js 1 100",
 data: bundle,
 encoding: "gzip",
 });

 expect(new TextDecoder().decode(brotli ?? new Uint8Array())).toContain("br:");
 expect(new TextDecoder().decode(gzipped ?? new Uint8Array())).toContain("gzip:");
 });

 it("skips payloads too small to be worth compressing", async () => {
 let compressCalls = 0;
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 return data;
 });

 const result = await cache.get({
 cacheKey: "tiny.js 1 8",
 data: new TextEncoder().encode("const a=1;"),
 encoding: "gzip",
 });

 expect(result).toBeNull();
 expect(compressCalls).toBe(0);
 });

 it("declines a result that did not get smaller", async () => {
 const cache = makeStaticCompressionCache(async (data) => new Uint8Array(data.byteLength + 32));

 const result = await cache.get({
 cacheKey: "incompressible.bin 1 100",
 data: bundle,
 encoding: "gzip",
 });

 expect(result).toBeNull();
 expect(cache.retainedByteLength).toBe(0);
 });

 it("really shrinks a realistic bundle with the default compressor", async () => {
 const cache = makeStaticCompressionCache();

 const compressed = await cache.get({
 cacheKey: "real.js 1 100",
 data: bundle,
 encoding: "br",
 });

 expect(compressed).not.toBeNull();
 expect((compressed as Uint8Array).byteLength).toBeLessThan(bundle.byteLength / 2);
 });
});
Loading
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Remove or un-stick sticky/fixed headers that block content\n(function() {\n function unstick() {\n document.querySelectorAll('header, nav, [role=\"banner\"], .header, .navbar, .sticky, .fixed-top, [style*=\"position: fixed\"], [style*=\"position:sticky\"]').forEach(function(el) {\n if (el.style.position === 'fixed' || el.style.position === 'sticky' || \n getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {\n el.style.position = 'static';\n el.style.top = 'auto';\n el.style.zIndex = 'auto';\n }\n });\n }\n \n unstick();\n \n var observer = new MutationObserver(unstick);\n observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });\n})();", "Kill Sticky Headers");
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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Compress and cache packaged web assets#4516

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Compress and cache packaged web assets
#4516
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93bcde9

Compress and cache packaged web assets


yashranaway Jul 25, 2026
c31c1aa

Compress the SPA fallback and share in-flight compressions


yashranaway Jul 25, 2026
4c66786

Key the SPA fallback compression by content


yashranaway Jul 25, 2026

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86 changes: 82 additions & 4 deletions
apps/server/src/http.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -37,6 +37,13 @@ import {
} from "./auth/http.ts";
import * as ServerEnvironment from "./environment/ServerEnvironment.ts";
import { browserApiCorsAllowedHeaders, browserApiCorsAllowedMethods } from "./httpCors.ts";
import {
 contentCacheKey,
 isCompressibleContentType,
 makeStaticCompressionCache,
 negotiateStaticEncoding,
 resolveStaticCacheControl,
} from "./staticAssetDelivery.ts";

const OTLP_TRACES_PROXY_PATH = "/api/observability/v1/traces";
const LOOPBACK_HOSTNAMES = new Set(["127.0.0.1", "::1", "localhost"]);
Expand DownExpand Up@@ -204,6 +211,8 @@ export const assetRouteLayer = HttpRouter.add(
 }),
);

const staticCompressionCache = makeStaticCompressionCache();

export const staticAndDevRouteLayer = HttpRouter.add(
 "GET",
 "*",
Expand DownExpand Up@@ -273,9 +282,18 @@ export const staticAndDevRouteLayer = HttpRouter.add(
 if (!indexData) {
 return HttpServerResponse.text("Not Found", { status: 404 });
 }
 return HttpServerResponse.uint8Array(indexData, {
status: 200,
 return yield* respondWithStaticFile({
data: indexData,
 contentType: "text/html; charset=utf-8",
 // The SPA fallback always revalidates so a new build is picked up.
 cacheControl: resolveStaticCacheControl("index.html"),
 // Every deep link lands here, so the document is worth compressing.
 // This is the one path whose file keeps a stable name across builds,
 // so it is keyed by content: metadata read separately from the bytes
 // could describe a different build than the one being served. The
 // document is small enough for hashing it to be cheap.
 cacheKey: contentCacheKey(indexData),
 acceptEncoding: request.headers["accept-encoding"],
 });
 }

Expand All@@ -285,9 +303,69 @@ export const staticAndDevRouteLayer = HttpRouter.add(
 return HttpServerResponse.text("Internal Server Error", { status: 500 });
 }

 return HttpServerResponse.uint8Array(data, {
status: 200,
 return yield* respondWithStaticFile({
data,
 contentType,
 cacheControl: resolveStaticCacheControl(staticRelativePath),
 cacheKey: staticCacheKey(filePath, fileInfo),
 acceptEncoding: request.headers["accept-encoding"],
 });
 }),
);

/**
 * Identifies a build of a file for the compression cache, without hashing
 * payloads that can run to megabytes. The stat is taken before the bytes are
 * read, so a rebuild landing between the two can only orphan an entry under
 * the superseded key, never publish those bytes under the newer one. Files
 * whose contents change without their name are keyed by content instead; the
 * rest carry a content hash in their filename already.
 */
function staticCacheKey(filePath: string, info: FileSystem.File.Info): string {
 const mtimeMs = info.mtime.pipe(
 Option.map((mtime) => mtime.getTime()),
 Option.getOrElse(() => 0),
 );
 return `${filePath} ${mtimeMs} ${info.size}`;
}

const respondWithStaticFile = Effect.fn("staticAndDevRoute.respond")(function* (input: {
 readonly data: Uint8Array;
 readonly contentType: string;
 readonly cacheControl: string;
 /** Null for the SPA fallback, whose bytes are re-read on every request. */
 readonly cacheKey: string | null;
 readonly acceptEncoding: string | undefined;
}) {
 const headers: Record<string, string> = {
 "Cache-Control": input.cacheControl,
 };

 const encoding = isCompressibleContentType(input.contentType)
 ? negotiateStaticEncoding(input.acceptEncoding)
 : null;
 if (isCompressibleContentType(input.contentType)) {
 // Announce negotiation even when this client took the identity encoding,
 // so shared caches do not hand a compressed body to a client that
 // cannot read it.
 headers["Vary"] = "Accept-Encoding";
 }

 const cacheKey = input.cacheKey;
 const compressed =
 encoding && cacheKey !== null
 ? yield* Effect.tryPromise(() =>
 staticCompressionCache.get({ cacheKey, data: input.data, encoding }),
 ).pipe(Effect.orElseSucceed(() => null))
 : null;

 if (compressed && encoding) {
 headers["Content-Encoding"] = encoding;
 }

 return HttpServerResponse.uint8Array(compressed ?? input.data, {
 status: 200,
 contentType: input.contentType,
 headers,
 });
});

223 changes: 223 additions & 0 deletions
apps/server/src/staticAssetDelivery.test.ts

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Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,223 @@
import { describe, expect, it } from "vite-plus/test";

import {
 contentCacheKey,
 isCompressibleContentType,
 makeStaticCompressionCache,
 negotiateStaticEncoding,
 resolveStaticCacheControl,
} from "./staticAssetDelivery.ts";

describe("contentCacheKey", () => {
 const encode = (value: string) => new TextEncoder().encode(value);

 it("keys identical content the same way", () => {
 expect(contentCacheKey(encode("<html>a</html>"))).toBe(
 contentCacheKey(encode("<html>a</html>")),
 );
 });

 it("separates content of the same length", () => {
 // A rebuild can reuse a filename, a size, and even a timestamp, so the
 // key has to come from the bytes themselves.
 expect(contentCacheKey(encode("<html>a</html>"))).not.toBe(
 contentCacheKey(encode("<html>b</html>")),
 );
 });
});

describe("resolveStaticCacheControl", () => {
 it("marks content-hashed bundle assets immutable", () => {
 expect(resolveStaticCacheControl("assets/index-DxV9k2Qp.js")).toBe(
 "public, max-age=31536000, immutable",
 );
 expect(resolveStaticCacheControl("assets/style-a1b2c3d4.css")).toBe(
 "public, max-age=31536000, immutable",
 );
 });

 it("revalidates entry documents and unhashed files", () => {
 expect(resolveStaticCacheControl("index.html")).toBe("no-cache");
 expect(resolveStaticCacheControl("/index.html")).toBe("no-cache");
 // No hash means a rebuild reuses the name, so it must not be pinned.
 expect(resolveStaticCacheControl("assets/logo.svg")).toBe("no-cache");
 expect(resolveStaticCacheControl("favicon.ico")).toBe("no-cache");
 });
});

describe("negotiateStaticEncoding", () => {
 it("prefers brotli when the client accepts both", () => {
 expect(negotiateStaticEncoding("gzip, deflate, br")).toBe("br");
 });

 it("falls back to gzip when brotli is absent", () => {
 expect(negotiateStaticEncoding("gzip, deflate")).toBe("gzip");
 });

 it("returns null when nothing usable is offered", () => {
 expect(negotiateStaticEncoding(undefined)).toBeNull();
 expect(negotiateStaticEncoding("")).toBeNull();
 expect(negotiateStaticEncoding("deflate")).toBeNull();
 });

 it("honors explicit refusals expressed as q=0", () => {
 expect(negotiateStaticEncoding("br;q=0, gzip")).toBe("gzip");
 expect(negotiateStaticEncoding("gzip;q=0, br;q=0")).toBeNull();
 });

 it("accepts a wildcard offer", () => {
 expect(negotiateStaticEncoding("*")).toBe("br");
 });
});

describe("isCompressibleContentType", () => {
 it("compresses text and structured payloads", () => {
 expect(isCompressibleContentType("text/html; charset=utf-8")).toBe(true);
 expect(isCompressibleContentType("application/javascript")).toBe(true);
 expect(isCompressibleContentType("image/svg+xml")).toBe(true);
 });

 it("leaves already-compressed binaries alone", () => {
 expect(isCompressibleContentType("image/png")).toBe(false);
 expect(isCompressibleContentType("font/woff2")).toBe(false);
 expect(isCompressibleContentType("application/octet-stream")).toBe(false);
 });
});

describe("makeStaticCompressionCache", () => {
 const bundle = new TextEncoder().encode("export const value = 1;\n".repeat(500));

 it("compresses a payload once and reuses the result", async () => {
 let compressCalls = 0;
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 return data.subarray(0, 64);
 });

 const first = await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" });
 const second = await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" });

 expect(first).not.toBeNull();
 expect(second).toBe(first);
 expect(compressCalls).toBe(1);
 });

 it("compresses once for a burst of concurrent requests", async () => {
 let compressCalls = 0;
 let release = () => {};
 const started = new Promise<void>((resolve) => {
 release = resolve;
 });
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 await started;
 return data.subarray(0, 64);
 });

 const requests = [
 cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" }),
 cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" }),
 cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" }),
 ];
 release();
 const results = await Promise.all(requests);

 expect(compressCalls).toBe(1);
 expect(results[1]).toBe(results[0]);
 expect(results[2]).toBe(results[0]);
 });

 it("retries after a failed compression instead of caching the failure", async () => {
 let compressCalls = 0;
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 if (compressCalls === 1) throw new Error("zlib buffer error");
 return data.subarray(0, 64);
 });

 await expect(
 cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" }),
 ).rejects.toThrow("zlib buffer error");

 const retried = await cache.get({
 cacheKey: "bundle.js 1 100",
 data: bundle,
 encoding: "gzip",
 });

 expect(compressCalls).toBe(2);
 expect(retried).not.toBeNull();
 });

 it("recompresses when the file changes underneath the same path", async () => {
 let compressCalls = 0;
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 return data.subarray(0, 64);
 });

 await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" });
 await cache.get({ cacheKey: "bundle.js 2 140", data: bundle, encoding: "gzip" });

 expect(compressCalls).toBe(2);
 });

 it("keeps brotli and gzip results apart", async () => {
 const cache = makeStaticCompressionCache(async (data, encoding) =>
 new TextEncoder().encode(`${encoding}:${data.byteLength}`),
 );

 const brotli = await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" });
 const gzipped = await cache.get({
 cacheKey: "bundle.js 1 100",
 data: bundle,
 encoding: "gzip",
 });

 expect(new TextDecoder().decode(brotli ?? new Uint8Array())).toContain("br:");
 expect(new TextDecoder().decode(gzipped ?? new Uint8Array())).toContain("gzip:");
 });

 it("skips payloads too small to be worth compressing", async () => {
 let compressCalls = 0;
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 return data;
 });

 const result = await cache.get({
 cacheKey: "tiny.js 1 8",
 data: new TextEncoder().encode("const a=1;"),
 encoding: "gzip",
 });

 expect(result).toBeNull();
 expect(compressCalls).toBe(0);
 });

 it("declines a result that did not get smaller", async () => {
 const cache = makeStaticCompressionCache(async (data) => new Uint8Array(data.byteLength + 32));

 const result = await cache.get({
 cacheKey: "incompressible.bin 1 100",
 data: bundle,
 encoding: "gzip",
 });

 expect(result).toBeNull();
 expect(cache.retainedByteLength).toBe(0);
 });

 it("really shrinks a realistic bundle with the default compressor", async () => {
 const cache = makeStaticCompressionCache();

 const compressed = await cache.get({
 cacheKey: "real.js 1 100",
 data: bundle,
 encoding: "br",
 });

 expect(compressed).not.toBeNull();
 expect((compressed as Uint8Array).byteLength).toBeLessThan(bundle.byteLength / 2);
 });
});
Loading
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Universal Dark Mode - works on any site\n(function() {\n var enabled = true;\n \n function applyDarkMode() {\n if (!enabled) return;\n \n // Create style element if it doesn't exist\n var style = document.getElementById('universal-dark-mode-style');\n if (!style) {\n style = document.createElement('style');\n style.id = 'universal-dark-mode-style';\n document.head.appendChild(style);\n }\n \n // Dark mode CSS - inverts colors but preserves images/video\n style.textContent = '\n /* Invert everything except media */\n html {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #1a1a2e !important;\n }\n \n /* Restore images, videos, iframes, canvas */\n img, video, iframe, canvas, svg, picture, [style*=\"background-image\"] {\n filter: invert(1) hue-rotate(180deg) !important;\n }\n \n /* Preserve specific elements that should not be inverted */\n .no-dark-mode, .no-dark-mode *,\n [data-theme=\"light\"], [data-theme=\"light\"],\n .ace_editor, .ace_editor *,\n .CodeMirror, .CodeMirror *,\n .monaco-editor, .monaco-editor *,\n .markdown-body pre, .markdown-body pre *,\n .highlight, .highlight *,\n pre code, pre code * {\n filter: none !important;\n }\n \n /* Fix common UI elements */\n .modal, .popup, .dropdown-menu, .tooltip, .popover {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #2d2d44 !important;\n border-color: #444 !important;\n }\n \n /* Scrollbars */\n ::-webkit-scrollbar { background: #1a1a2e !important; }\n ::-webkit-scrollbar-thumb { background: #444 !important; }\n ::-webkit-scrollbar-thumb:hover { background: #555 !important; }\n \n /* Selection */\n ::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ';\n }\n \n function removeDarkMode() {\n var style = document.getElementById('universal-dark-mode-style');\n if (style) style.remove();\n }\n \n // Toggle with Alt+Shift+D\n document.addEventListener('keydown', function(e) {\n if (e.altKey && e.shiftKey && e.key === 'D') {\n e.preventDefault();\n enabled = !enabled;\n if (enabled) {\n applyDarkMode();\n console.log('[Universal Dark Mode] Enabled');\n } else {\n removeDarkMode();\n console.log('[Universal Dark Mode] Disabled');\n }\n }\n });\n \n // Apply on load\n applyDarkMode();\n \n // Re-apply on dynamic content\n var observer = new MutationObserver(function(mutations) {\n if (enabled && !document.getElementById('universal-dark-mode-style')) {\n applyDarkMode();\n }\n });\n observer.observe(document.head, { childList: true });\n \n console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');\n})();", "Universal Dark Mode");
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();

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Compress and cache packaged web assets#4516

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 Open

yashranaway
wants to merge
3
commits into

base:main
Choose a base branch

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+490

−4

 Open


Compress and cache packaged web assets
#4516
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93bcde9

Compress and cache packaged web assets


yashranaway Jul 25, 2026
c31c1aa

Compress the SPA fallback and share in-flight compressions


yashranaway Jul 25, 2026
4c66786

Key the SPA fallback compression by content


yashranaway Jul 25, 2026

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86 changes: 82 additions & 4 deletions
apps/server/src/http.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -37,6 +37,13 @@ import {
} from "./auth/http.ts";
import * as ServerEnvironment from "./environment/ServerEnvironment.ts";
import { browserApiCorsAllowedHeaders, browserApiCorsAllowedMethods } from "./httpCors.ts";
import {
 contentCacheKey,
 isCompressibleContentType,
 makeStaticCompressionCache,
 negotiateStaticEncoding,
 resolveStaticCacheControl,
} from "./staticAssetDelivery.ts";

const OTLP_TRACES_PROXY_PATH = "/api/observability/v1/traces";
const LOOPBACK_HOSTNAMES = new Set(["127.0.0.1", "::1", "localhost"]);
Expand DownExpand Up@@ -204,6 +211,8 @@ export const assetRouteLayer = HttpRouter.add(
 }),
);

const staticCompressionCache = makeStaticCompressionCache();

export const staticAndDevRouteLayer = HttpRouter.add(
 "GET",
 "*",
Expand DownExpand Up@@ -273,9 +282,18 @@ export const staticAndDevRouteLayer = HttpRouter.add(
 if (!indexData) {
 return HttpServerResponse.text("Not Found", { status: 404 });
 }
 return HttpServerResponse.uint8Array(indexData, {
status: 200,
 return yield* respondWithStaticFile({
data: indexData,
 contentType: "text/html; charset=utf-8",
 // The SPA fallback always revalidates so a new build is picked up.
 cacheControl: resolveStaticCacheControl("index.html"),
 // Every deep link lands here, so the document is worth compressing.
 // This is the one path whose file keeps a stable name across builds,
 // so it is keyed by content: metadata read separately from the bytes
 // could describe a different build than the one being served. The
 // document is small enough for hashing it to be cheap.
 cacheKey: contentCacheKey(indexData),
 acceptEncoding: request.headers["accept-encoding"],
 });
 }

Expand All@@ -285,9 +303,69 @@ export const staticAndDevRouteLayer = HttpRouter.add(
 return HttpServerResponse.text("Internal Server Error", { status: 500 });
 }

 return HttpServerResponse.uint8Array(data, {
status: 200,
 return yield* respondWithStaticFile({
data,
 contentType,
 cacheControl: resolveStaticCacheControl(staticRelativePath),
 cacheKey: staticCacheKey(filePath, fileInfo),
 acceptEncoding: request.headers["accept-encoding"],
 });
 }),
);

/**
 * Identifies a build of a file for the compression cache, without hashing
 * payloads that can run to megabytes. The stat is taken before the bytes are
 * read, so a rebuild landing between the two can only orphan an entry under
 * the superseded key, never publish those bytes under the newer one. Files
 * whose contents change without their name are keyed by content instead; the
 * rest carry a content hash in their filename already.
 */
function staticCacheKey(filePath: string, info: FileSystem.File.Info): string {
 const mtimeMs = info.mtime.pipe(
 Option.map((mtime) => mtime.getTime()),
 Option.getOrElse(() => 0),
 );
 return `${filePath} ${mtimeMs} ${info.size}`;
}

const respondWithStaticFile = Effect.fn("staticAndDevRoute.respond")(function* (input: {
 readonly data: Uint8Array;
 readonly contentType: string;
 readonly cacheControl: string;
 /** Null for the SPA fallback, whose bytes are re-read on every request. */
 readonly cacheKey: string | null;
 readonly acceptEncoding: string | undefined;
}) {
 const headers: Record<string, string> = {
 "Cache-Control": input.cacheControl,
 };

 const encoding = isCompressibleContentType(input.contentType)
 ? negotiateStaticEncoding(input.acceptEncoding)
 : null;
 if (isCompressibleContentType(input.contentType)) {
 // Announce negotiation even when this client took the identity encoding,
 // so shared caches do not hand a compressed body to a client that
 // cannot read it.
 headers["Vary"] = "Accept-Encoding";
 }

 const cacheKey = input.cacheKey;
 const compressed =
 encoding && cacheKey !== null
 ? yield* Effect.tryPromise(() =>
 staticCompressionCache.get({ cacheKey, data: input.data, encoding }),
 ).pipe(Effect.orElseSucceed(() => null))
 : null;

 if (compressed && encoding) {
 headers["Content-Encoding"] = encoding;
 }

 return HttpServerResponse.uint8Array(compressed ?? input.data, {
 status: 200,
 contentType: input.contentType,
 headers,
 });
});

223 changes: 223 additions & 0 deletions
apps/server/src/staticAssetDelivery.test.ts

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import { describe, expect, it } from "vite-plus/test";

import {
 contentCacheKey,
 isCompressibleContentType,
 makeStaticCompressionCache,
 negotiateStaticEncoding,
 resolveStaticCacheControl,
} from "./staticAssetDelivery.ts";

describe("contentCacheKey", () => {
 const encode = (value: string) => new TextEncoder().encode(value);

 it("keys identical content the same way", () => {
 expect(contentCacheKey(encode("<html>a</html>"))).toBe(
 contentCacheKey(encode("<html>a</html>")),
 );
 });

 it("separates content of the same length", () => {
 // A rebuild can reuse a filename, a size, and even a timestamp, so the
 // key has to come from the bytes themselves.
 expect(contentCacheKey(encode("<html>a</html>"))).not.toBe(
 contentCacheKey(encode("<html>b</html>")),
 );
 });
});

describe("resolveStaticCacheControl", () => {
 it("marks content-hashed bundle assets immutable", () => {
 expect(resolveStaticCacheControl("assets/index-DxV9k2Qp.js")).toBe(
 "public, max-age=31536000, immutable",
 );
 expect(resolveStaticCacheControl("assets/style-a1b2c3d4.css")).toBe(
 "public, max-age=31536000, immutable",
 );
 });

 it("revalidates entry documents and unhashed files", () => {
 expect(resolveStaticCacheControl("index.html")).toBe("no-cache");
 expect(resolveStaticCacheControl("/index.html")).toBe("no-cache");
 // No hash means a rebuild reuses the name, so it must not be pinned.
 expect(resolveStaticCacheControl("assets/logo.svg")).toBe("no-cache");
 expect(resolveStaticCacheControl("favicon.ico")).toBe("no-cache");
 });
});

describe("negotiateStaticEncoding", () => {
 it("prefers brotli when the client accepts both", () => {
 expect(negotiateStaticEncoding("gzip, deflate, br")).toBe("br");
 });

 it("falls back to gzip when brotli is absent", () => {
 expect(negotiateStaticEncoding("gzip, deflate")).toBe("gzip");
 });

 it("returns null when nothing usable is offered", () => {
 expect(negotiateStaticEncoding(undefined)).toBeNull();
 expect(negotiateStaticEncoding("")).toBeNull();
 expect(negotiateStaticEncoding("deflate")).toBeNull();
 });

 it("honors explicit refusals expressed as q=0", () => {
 expect(negotiateStaticEncoding("br;q=0, gzip")).toBe("gzip");
 expect(negotiateStaticEncoding("gzip;q=0, br;q=0")).toBeNull();
 });

 it("accepts a wildcard offer", () => {
 expect(negotiateStaticEncoding("*")).toBe("br");
 });
});

describe("isCompressibleContentType", () => {
 it("compresses text and structured payloads", () => {
 expect(isCompressibleContentType("text/html; charset=utf-8")).toBe(true);
 expect(isCompressibleContentType("application/javascript")).toBe(true);
 expect(isCompressibleContentType("image/svg+xml")).toBe(true);
 });

 it("leaves already-compressed binaries alone", () => {
 expect(isCompressibleContentType("image/png")).toBe(false);
 expect(isCompressibleContentType("font/woff2")).toBe(false);
 expect(isCompressibleContentType("application/octet-stream")).toBe(false);
 });
});

describe("makeStaticCompressionCache", () => {
 const bundle = new TextEncoder().encode("export const value = 1;\n".repeat(500));

 it("compresses a payload once and reuses the result", async () => {
 let compressCalls = 0;
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 return data.subarray(0, 64);
 });

 const first = await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" });
 const second = await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" });

 expect(first).not.toBeNull();
 expect(second).toBe(first);
 expect(compressCalls).toBe(1);
 });

 it("compresses once for a burst of concurrent requests", async () => {
 let compressCalls = 0;
 let release = () => {};
 const started = new Promise<void>((resolve) => {
 release = resolve;
 });
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 await started;
 return data.subarray(0, 64);
 });

 const requests = [
 cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" }),
 cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" }),
 cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" }),
 ];
 release();
 const results = await Promise.all(requests);

 expect(compressCalls).toBe(1);
 expect(results[1]).toBe(results[0]);
 expect(results[2]).toBe(results[0]);
 });

 it("retries after a failed compression instead of caching the failure", async () => {
 let compressCalls = 0;
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 if (compressCalls === 1) throw new Error("zlib buffer error");
 return data.subarray(0, 64);
 });

 await expect(
 cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" }),
 ).rejects.toThrow("zlib buffer error");

 const retried = await cache.get({
 cacheKey: "bundle.js 1 100",
 data: bundle,
 encoding: "gzip",
 });

 expect(compressCalls).toBe(2);
 expect(retried).not.toBeNull();
 });

 it("recompresses when the file changes underneath the same path", async () => {
 let compressCalls = 0;
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 return data.subarray(0, 64);
 });

 await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "gzip" });
 await cache.get({ cacheKey: "bundle.js 2 140", data: bundle, encoding: "gzip" });

 expect(compressCalls).toBe(2);
 });

 it("keeps brotli and gzip results apart", async () => {
 const cache = makeStaticCompressionCache(async (data, encoding) =>
 new TextEncoder().encode(`${encoding}:${data.byteLength}`),
 );

 const brotli = await cache.get({ cacheKey: "bundle.js 1 100", data: bundle, encoding: "br" });
 const gzipped = await cache.get({
 cacheKey: "bundle.js 1 100",
 data: bundle,
 encoding: "gzip",
 });

 expect(new TextDecoder().decode(brotli ?? new Uint8Array())).toContain("br:");
 expect(new TextDecoder().decode(gzipped ?? new Uint8Array())).toContain("gzip:");
 });

 it("skips payloads too small to be worth compressing", async () => {
 let compressCalls = 0;
 const cache = makeStaticCompressionCache(async (data) => {
 compressCalls += 1;
 return data;
 });

 const result = await cache.get({
 cacheKey: "tiny.js 1 8",
 data: new TextEncoder().encode("const a=1;"),
 encoding: "gzip",
 });

 expect(result).toBeNull();
 expect(compressCalls).toBe(0);
 });

 it("declines a result that did not get smaller", async () => {
 const cache = makeStaticCompressionCache(async (data) => new Uint8Array(data.byteLength + 32));

 const result = await cache.get({
 cacheKey: "incompressible.bin 1 100",
 data: bundle,
 encoding: "gzip",
 });

 expect(result).toBeNull();
 expect(cache.retainedByteLength).toBe(0);
 });

 it("really shrinks a realistic bundle with the default compressor", async () => {
 const cache = makeStaticCompressionCache();

 const compressed = await cache.get({
 cacheKey: "real.js 1 100",
 data: bundle,
 encoding: "br",
 });

 expect(compressed).not.toBeNull();
 expect((compressed as Uint8Array).byteLength).toBeLessThan(bundle.byteLength / 2);
 });
});
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