hyperframes/scripts/check-pr-captures.mjs at main · crmne/hyperframes · GitHub

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#!/usr/bin/env node

// Fail a PR touching packages/studio or packages/player unless its body has Before and After sections with media.

// usage: node scripts/check-pr-captures.mjs --base origin/main --head <sha>; the body arrives in the env (see main).

import { execFileSync } from "node:child_process";

import { createHash } from "node:crypto";

import { realpathSync } from "node:fs";

import { pathToFileURL } from "node:url";

export const WATCHED_PREFIXES = ["packages/studio/", "packages/player/"];

export const NO_VISIBLE_CHANGE_MAX_LINES = 20;

export const VISUAL_EXTENSIONS = [".tsx", ".css", ".html"];

const MEDIA_PATH = /\.(?:png|jpe?g|gif|webp|svg|mp4|mov|webm)$/i;

const ATTACHMENT_PATH = /^\/user-attachments\/assets\/[\w-]+/;

const IMAGE_EMBED =

/!\[[^\]]*\]\(\s*https?:\/\/|<(?:img|video|source)\b[^>]*\bsrc=["']https?:\/\//i;

const TRAILING_PUNCTUATION = /[.,;:!?*_`]+$/;

const ANY_URL = /https?:\/\/[^\s)"'<>\]]+/gi;

function parseUrl(raw) {

try {

return new URL(raw);

} catch {

return null;

}

}

const isAttachmentUrl = (url) =>

url.hostname === "github.com" && ATTACHMENT_PATH.test(url.pathname);

function isMediaUrl(raw) {

const url = parseUrl(raw);

return url !== null && (isAttachmentUrl(url) || MEDIA_PATH.test(url.pathname));

}

const TEST_FILE = /\.(?:test|spec)\.[jt]sx?$/;

const CAPTURE_TITLES = {

before: /^before(?:\s*[:(].*|\s+[-–—]\s.*)?$/i,

after: /^after(?:\s*[:(].*|\s+[-–—]\s.*)?$/i,

noVisibleChange: /^no visible change\b/i,

};

const isCapture = (title) => Object.values(CAPTURE_TITLES).some((re) => re.test(title));

const SETEXT = [

[/^=+\s*$/, "#"],

[/^-{2,}\s*$/, "##"],

];

/** GitHub hides an unclosed comment to the end of the body; repeat so removal cannot join fragments into a new one. */

function stripComments(body) {

let text = body;

let previous;

do {

previous = text;

text = text.replace(/|$)/g, "");

} while (text !== previous);

return text;

}

const FENCE = /^ {0,3}(`{3,}|~{3,})(.*)$/;

const closesFence = (open, line) => {

const [, marker = "", rest = ""] = FENCE.exec(line) ?? [];

return marker[0] === open[0] && marker.length >= open.length && rest.trim() === "";

};

const openingMarker = (line) => FENCE.exec(line)?.[1] ?? null;

/** The open fence marker after this line (CommonMark: same character, at least as long, to close), or null. */

const nextFence = (open, line) => {

if (open) return closesFence(open, line) ? null : open;

return openingMarker(line);

};

function blankFences(lines) {

let open = null;

return lines.map((line) => {

const before = open;

open = nextFence(open, line);

return before || open ? "" : line;

});

}

const setextPrefix = (underline) => SETEXT.find(([re]) => re.test(underline))?.[1];

function promoteSetext(lines) {

const padded = [...lines, ""];

return lines.map((line, i) => {

const prefix = isCapture(line.trim()) ? setextPrefix(padded[i + 1]) : undefined;

return prefix ? `${prefix} ${line.trim()}` : line;

});

}

/** Drop HTML comments and fenced code, and promote setext capture headings, so none can fake a section. */

const normalize = (body) => promoteSetext(blankFences(stripComments(body).split(/\r?\n/)));

/** Sections run to the next heading of the same or a higher level, or to the next capture heading. */

export function parseSections(body) {

const lines = normalize(body);

const headings = [];

lines.forEach((line, index) => {

const match = /^(#{1,6})\s+(.+?)\s*#*\s*$/.exec(line);

if (match) headings.push({ level: match[1].length, title: match[2].trim(), index });

});

return headings.map((heading, i) => {

const end = headings

.slice(i + 1)

.find((next) => next.level <= heading.level || isCapture(next.title));

return {

title: heading.title,

text: lines.slice(heading.index + 1, end ? end.index : lines.length).join("\n"),

};

});

}

export function hasMedia(text) {

return IMAGE_EMBED.test(text) || (text.match(ANY_URL) ?? []).some(isMediaUrl);

}

function findSection(sections, name) {

return sections.find((section) => CAPTURE_TITLES[name].test(section.title));

}

function parseRecord(record) {

const [added, deleted, ...rest] = record.split("\t");

const binary = added === "-" || deleted === "-";

const lines = binary ? NO_VISIBLE_CHANGE_MAX_LINES : Number(added) + Number(deleted);

return { path: rest.join("\t"), lines };

}

const isWatched = (path) =>

path !== "" && WATCHED_PREFIXES.some((prefix) => path.startsWith(prefix));

/** Parse `git diff --numstat -z --no-renames`, keeping watched paths. A binary file counts as a full budget. */

export const parseNumstat = (numstat) =>

numstat

.split("\0")

.map(parseRecord)

.filter((file) => isWatched(file.path));

const isVisualFile = (path) =>

VISUAL_EXTENSIONS.some((ext) => path.endsWith(ext)) && !TEST_FILE.test(path);

/** Why a "No visible change" declaration does not hold for this diff; empty means it holds. */

export function noVisibleChangeFailures(files) {

const failures = [];

const lines = files.reduce((sum, file) => sum + file.lines, 0);

if (lines >= NO_VISIBLE_CHANGE_MAX_LINES) {

failures.push(

`the diff changes ${lines} lines under packages/studio and packages/player; the limit is under ${NO_VISIBLE_CHANGE_MAX_LINES}`,

);

}

const visual = files.filter((file) => isVisualFile(file.path));

if (visual.length > 0) {

failures.push(

`the diff touches ${VISUAL_EXTENSIONS.join(", ")} files: ${visual.map((file) => file.path).join(", ")}`,

);

}

return failures;

}

function sectionProblem(section, name) {

if (!section) return `the body has no "${name}" heading`;

return hasMedia(section.text) ? null : `the "${name}" section has no image or video`;

}

const captureProblems = (sections) =>

[

sectionProblem(findSection(sections, "before"), "Before"),

sectionProblem(findSection(sections, "after"), "After"),

].filter(Boolean);

function noVisibleChangeVerdict(sections, files) {

if (!findSection(sections, "noVisibleChange")) return { holds: false, problems: [] };

const failures = noVisibleChangeFailures(files);

const problems = failures.map((failure) => `"No visible change" does not apply: ${failure}`);

return { holds: failures.length === 0, problems };

}

const PASS = { ok: true, problems: [] };

export function evaluate({ body, files }) {

if (files.length === 0) return PASS;

const sections = parseSections(body);

const captures = captureProblems(sections);

if (captures.length === 0) return PASS;

const verdict = noVisibleChangeVerdict(sections, files);

if (verdict.holds) return PASS;

return { ok: false, problems: [...verdict.problems, ...captures] };

}

const DOWNLOAD_ATTEMPTS = 5;

// A freshly uploaded GitHub attachment can 404 for up to a few minutes before

// its storage read-path catches up with the write — observed up to ~3 minutes

// in production, with no edit to the PR in between. The deadline and delays

// below give a 404 on an attachment host room to clear before this gives up.

const DOWNLOAD_DEADLINE_MS = 180_000;

const RETRY_DELAYS_MS = [5_000, 15_000, 30_000, 60_000];

const MAX_REDIRECTS = 5;

const REDIRECT_STATUSES = new Set([301, 302, 303, 307, 308]);

const MAX_ASSET_BYTES = 100 * 1024 * 1024;

const MAX_CAPTURES = 12;

const MAX_TOTAL_BYTES = 300 * 1024 * 1024;

/** An attachment redirects to GitHub's own signed-storage bucket; a redirect anywhere else is not followed. */

const TRUSTED_REDIRECT_HOST =

/^(([a-z0-9-]+\.)*(github\.com|githubusercontent\.com)|github-production-[a-z0-9-]+-asset-[a-z0-9]+\.s3\.amazonaws\.com)$/;

class NonRetryable extends Error {}

/** Our own byte cap tripped: unlike a failed download, this never justifies skipping the check. */

export class LimitExceeded extends NonRetryable {}

/** The next hop of a redirect, refused unless it stays on https and on a GitHub asset host. */

function trustedNextHop(response, current) {

const next = new URL(response.headers.get("location") ?? "", current);

if (next.protocol === "https:" && TRUSTED_REDIRECT_HOST.test(next.hostname)) return next.href;

throw new NonRetryable(`redirected to ${next.hostname}, which is not a GitHub asset host`);

}

/** One GET, following redirects only to hosts that serve GitHub attachments. */

async function fetchTrusted(url, fetchImpl, signal) {

let current = url;

for (let hop = 0; hop <= MAX_REDIRECTS; hop++) {

const response = await fetchImpl(current, { redirect: "manual", signal });

if (!REDIRECT_STATUSES.has(response.status)) return response;

current = trustedNextHop(response, current);

}

throw new NonRetryable("too many redirects");

}

/** Collects chunks, refusing once this asset or the shared budget of the whole check runs out of bytes. */

function cappedCollector(budget) {

const chunks = [];

let size = 0;

return {

size: () => size,

bytes: () => Buffer.concat(chunks),

take(chunk) {

size += chunk.byteLength;

budget.left -= chunk.byteLength;

if (size > MAX_ASSET_BYTES) throw new LimitExceeded(`larger than ${MAX_ASSET_BYTES} bytes`);

if (budget.left < 0)

throw new LimitExceeded(`captures together exceed ${MAX_TOTAL_BYTES} bytes`);

chunks.push(Buffer.from(chunk));

},

};

}

async function drainBody(response, take) {

if (!response.body?.getReader) return take(await response.arrayBuffer());

const reader = response.body.getReader();

try {

for (let part = await reader.read(); !part.done; part = await reader.read()) take(part.value);

} finally {

await reader.cancel().catch(() => {});

}

}

/** The body as bytes; an attempt that fails for any reason but our own cap gives its bytes back. */

async function readCapped(response, budget) {

const collector = cappedCollector(budget);

try {

await drainBody(response, collector.take);

} catch (error) {

if (!(error instanceof LimitExceeded)) budget.left += collector.size();

throw error;

}

return collector.bytes();

}

const isServerRetryable = (status) => status === 429 || status >= 500;

// A 404 is final for almost anything — but for a GitHub attachment URL, right

// after it was uploaded, it means "not replicated yet," not "does not exist."

// Reproduced this week: the same asset URL 404'd, then 200'd minutes later

// with no edit to the PR in between, and whichever asset had been attached

// most recently was always the one that failed. Scoped to the attachment host

// so a real 404 on any other URL (a typo'd link, a deleted gist) still fails fast.

const isRetryableAttachment404 = (status, url) => {

if (status !== 404) return false;

const parsed = parseUrl(url);

return parsed !== null && isAttachmentUrl(parsed);

};

const isRetryableStatus = (status, url) =>

isServerRetryable(status) || isRetryableAttachment404(status, url);

const pause = (ms) => new Promise((resolve) => setTimeout(resolve, ms));

/** One attempt: the bytes, or a NonRetryable for a final status, or a plain Error for a retryable one. */

async function attemptDownload(url, fetchImpl, signal, budget) {

const response = await fetchTrusted(url, fetchImpl, signal);

if (response.ok) return readCapped(response, budget);

const message = `HTTP ${response.status}`;

throw isRetryableStatus(response.status, url) ? new Error(message) : new NonRetryable(message);

}

async function waitForRetry(attempt, sleep, signal) {

if (attempt > 0) await sleep(RETRY_DELAYS_MS[attempt - 1]);

if (signal.aborted) throw new NonRetryable(`not finished within ${DOWNLOAD_DEADLINE_MS} ms`);

}

/** The bytes behind a capture URL; a 429, 5xx or network error is retried with backoff, any other status is final. */

export async function downloadAsset(

url,

fetchImpl = fetch,

sleep = pause,

budget = { left: MAX_TOTAL_BYTES },

) {

const signal = AbortSignal.timeout(DOWNLOAD_DEADLINE_MS);

let failure;

for (let attempt = 0; attempt < DOWNLOAD_ATTEMPTS; attempt++) {

await waitForRetry(attempt, sleep, signal);

try {

return await attemptDownload(url, fetchImpl, signal, budget);

} catch (error) {

if (error instanceof NonRetryable) throw error;

failure = error;

}

}

throw failure;

}

/** The asset a link names: query, fragment and default port do not change it. */

const linkIdentity = (url) => (url === null ? "" : `${url.origin}${url.pathname}`);

/** Only GitHub attachment URLs are downloaded: a body must not make the runner fetch an arbitrary host. */

const captureUrls = (section) => [

...new Set(

(section.text.match(ANY_URL) ?? [])

.map((raw) => parseUrl(raw.replace(TRAILING_PUNCTUATION, "")))

.filter((url) => url !== null && url.protocol === "https:" && isAttachmentUrl(url))

.map(linkIdentity),

),

];

const sha256 = (bytes) => createHash("sha256").update(bytes).digest("hex");

/** url -> hash for each capture, read one at a time so one large asset cannot starve a sibling of the shared budget. */

async function hashCaptures(name, urls, download) {

const hashed = [];

for (const url of urls) {

let bytes;

try {

bytes = await download(url);

} catch (error) {

const problem = `could not download ${name} asset ${url}: ${error.message}`;

hashed.push({ name, url, problem, refused: error instanceof LimitExceeded });

continue;

}

hashed.push({ name, url, hash: sha256(bytes) });

}

return hashed;

}

const noProblems = () => ({ unreadable: [], identical: [], refused: [], notices: [] });

const linkLimitProblem = (urls) =>

new Set(urls).size > MAX_CAPTURES

? {

...noProblems(),

refused: [`more than ${MAX_CAPTURES} capture links; attach fewer, longer clips`],

}

: null;

const perCheckDownloader = () => {

const budget = { left: MAX_TOTAL_BYTES };

return (url) => downloadAsset(url, fetch, pause, budget);

};

const identicalPairs = (befores, afters) =>

afters.flatMap((asset) =>

befores

.filter((old) => old.hash === asset.hash)

.map((old) => `After asset ${asset.url} is byte-identical to Before asset ${old.url}`),

);

async function compareCaptures(beforeUrls, afterUrls, download) {

const shared = afterUrls.filter((url) => beforeUrls.includes(url));

const unshared = (urls) => urls.filter((url) => !shared.includes(url));

const befores = await hashCaptures("Before", unshared(beforeUrls), download);

const afters = await hashCaptures("After", unshared(afterUrls), download);

const problems = [...befores, ...afters].filter((asset) => asset.problem);

const sameLink = shared.map((url) => `After asset ${url} is the same link as a Before asset`);

return {

unreadable: problems.filter((asset) => !asset.refused).map((asset) => asset.problem),

identical: [

...sameLink,

...identicalPairs(

befores.filter((asset) => asset.hash),

afters.filter((asset) => asset.hash),

),

],

refused: problems.filter((asset) => asset.refused).map((asset) => asset.problem),

};

}

const trimmedLinks = (section) =>

(section.text.match(ANY_URL) ?? []).map((raw) => raw.replace(TRAILING_PUNCTUATION, ""));

/** Media links the hash comparison cannot see: an http attachment is a typo to fix, any other host is only noted. */

function uncomparable(sections) {

const skipped = sections.flatMap(trimmedLinks).filter(isMediaUrl);

const comparable = new Set(sections.flatMap(captureUrls));

const rest = skipped.filter((raw) => !comparable.has(linkIdentity(parseUrl(raw))));

const insecure = rest.filter(

(raw) => parseUrl(raw)?.protocol === "http:" && isAttachmentUrl(parseUrl(raw)),

);

return {

refused: insecure.map((raw) => `${raw} is an http link; use the https link of the attachment`),

notices: rest

.filter((raw) => !insecure.includes(raw))

.map((raw) => `not compared, not a GitHub attachment: ${raw}`),

};

}

/** Every After asset must differ by content hash from every Before asset; an unreadable download is a problem. */

export async function duplicateCaptureProblems(body, download = perCheckDownloader()) {

const sections = parseSections(body);

const before = findSection(sections, "before");

const after = findSection(sections, "after");

if (!before || !after) return noProblems();

const beforeUrls = captureUrls(before);

const afterUrls = captureUrls(after);

const tooMany = linkLimitProblem([...beforeUrls, ...afterUrls]);

if (tooMany) return tooMany;

const compared = await compareCaptures(beforeUrls, afterUrls, download);

const skipped = uncomparable([before, after]);

return {

...compared,

refused: [...compared.refused, ...skipped.refused],

notices: skipped.notices,

};

}

export function attachCommand(prNumber) {

return `gh pr edit ${prNumber} --attach ./before.png --attach ./after.png`;

}

function flag(args, name, fallback) {

const at = args.indexOf(name);

return at === -1 ? fallback : args[at + 1];

}

function readNumstat(base, head) {

try {

return execFileSync("git", ["diff", "--numstat", "-z", "--no-renames", `${base}...${head}`], {

encoding: "utf8",

});

} catch (error) {

console.error(`cannot diff ${base}...${head}: ${error.message.trim()}`);

return process.exit(2);

}

}

function printFailure(problems, prNumber) {

console.error(

"This PR changes packages/studio or packages/player, so its body must show the behaviour.",

);

for (const problem of problems) console.error(` - ${problem}`);

console.error("\nAdd '## Before' and '## After' sections, each with an image or video, then:");

console.error(` ${attachCommand(prNumber)}`);

console.error("Only the PR description counts; captures posted as comments are not read.");

console.error(

"Edit the body text first: gh pr edit --body-file replaces the body and drops attachments.",

);

console.error(

`A change with no visible effect (under ${NO_VISIBLE_CHANGE_MAX_LINES} lines, no .tsx/.css/.html) may instead add a '## No visible change' section.`,

);

}

/** A fork's PR runs without secrets, so an unreadable capture there is skipped, never failed. */

export const isFork = (env) => Boolean(env.HEAD_REPO) && env.HEAD_REPO !== env.BASE_REPO;

export const blocking = (unreadable, mustFix, env) =>

mustFix.length > 0 || (unreadable.length > 0 && !isFork(env));

function printList(heading, problems, out = console.error) {

if (problems.length === 0) return;

out(heading);

for (const problem of problems) out(` - ${problem}`);

}

function reportCaptureProblems({ unreadable, identical, refused, notices }, env) {

const skipped =

"Skipped the duplicate-capture comparison: this PR is from a fork and a capture could not be downloaded without a token, which a fork cannot have.";

if (isFork(env)) printList(skipped, unreadable, console.log);

else printList("A capture could not be downloaded to compare:", unreadable);

printList(

"A capture under After is the same file as one under Before; re-attach the real After recording:",

identical,

);

printList("The capture comparison cannot pass as it stands:", refused);

printList("Links the duplicate check could not compare:", notices, console.log);

}

const prFromEnv = (env) => ({ body: env.PR_BODY ?? "", number: env.PR_NUMBER ?? "<number>" });

const findProblems = (body, files) =>

files.length > 0 ? duplicateCaptureProblems(body) : noProblems();

async function main() {

const args = process.argv.slice(2);

const numstat = readNumstat(flag(args, "--base", "origin/main"), flag(args, "--head", "HEAD"));

const { body, number } = prFromEnv(process.env);

const files = parseNumstat(numstat);

const { ok, problems } = evaluate({ body, files });

if (!ok) {

printFailure(problems, number);

process.exit(1);

}

const found = await findProblems(body, files);

reportCaptureProblems(found, process.env);

if (blocking(found.unreadable, [...found.identical, ...found.refused], process.env)) {

process.exit(1);

}

console.log("packages/studio and packages/player: captures present, or nothing to show.");

}

if (process.argv[1] && import.meta.url === pathToFileURL(realpathSync(process.argv[1])).href)

await main();