[wip] Redesign index page

.github/scripts/check-prompt-sync.mjs

@@ -0,0 +1,64 @@
+/**
+ * The agent setup prompt lives in two files:
+ *
+ *   snippets/setup-agent-prompt.mdx       — <Prompt> card used on the quickstart
+ *   snippets/setup-agent-prompt-text.mdx  — the same text as a JS string, used by
+ *                                           the introduction page's own prompt card
+ *
+ * They have to be separate because the <Prompt> component serializes its
+ * children's *source* rather than evaluating them, so it cannot be handed a
+ * variable. This script fails CI if the two ever drift apart.
+ */
+
+import { readFileSync } from "node:fs";
+
+const CARD = "snippets/setup-agent-prompt.mdx";
+const TEXT = "snippets/setup-agent-prompt-text.mdx";
+
+function fromPromptCard(path) {
+  const lines = readFileSync(path, "utf8").split("\n");
+  const open = lines.findIndex((l) => l.startsWith("<Prompt"));
+  const close = lines.findIndex((l) => l.trim() === "</Prompt>");
+  if (open === -1 || close === -1 || close < open) {
+    throw new Error(`${path}: could not find a <Prompt>...</Prompt> block`);
+  }
+  return lines.slice(open + 1, close).join("\n").trim();
+}
+
+function fromConstant(path) {
+  const src = readFileSync(path, "utf8");
+  const match = src.match(/export const SETUP_AGENT_PROMPT = `([\s\S]*)`;/);
+  if (!match) {
+    throw new Error(`${path}: could not find the SETUP_AGENT_PROMPT template literal`);
+  }
+  return match[1]
+    .replace(/\\`/g, "`")
+    .replace(/\\\$\{/g, "${")
+    .replace(/\\\\/g, "\\")
+    .trim();
+}
+
+const card = fromPromptCard(CARD);
+const text = fromConstant(TEXT);
+
+if (card === text) {
+  console.log(`The setup prompt matches in ${CARD} and ${TEXT}.`);
+  process.exit(0);
+}
+
+const cardLines = card.split("\n");
+const textLines = text.split("\n");
+const firstDiff = cardLines.findIndex((line, i) => line !== textLines[i]);
+
+console.error(`The setup prompt has drifted between ${CARD} and ${TEXT}.`);
+console.error("Edit one, then copy the change into the other.\n");
+
+if (firstDiff !== -1) {
+  console.error(`First difference at line ${firstDiff + 1}:`);
+  console.error(`  ${CARD}:\n    ${cardLines[firstDiff] ?? "(missing)"}`);
+  console.error(`  ${TEXT}:\n    ${textLines[firstDiff] ?? "(missing)"}`);
+} else {
+  console.error(`${CARD} has ${cardLines.length} lines, ${TEXT} has ${textLines.length}.`);
+}
+
+process.exit(1);

.github/workflows/check-prompt-sync.yml

@@ -0,0 +1,24 @@
+name: Check setup prompt sync
+
+on:
+  pull_request:
+    paths:
+      - snippets/setup-agent-prompt.mdx
+      - snippets/setup-agent-prompt-text.mdx
+      - .github/scripts/check-prompt-sync.mjs
+      - .github/workflows/check-prompt-sync.yml
+
+permissions:
+  contents: read
+
+jobs:
+  check:
+    name: Check setup prompt sync
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+      - uses: actions/setup-node@v6
+        with:
+          node-version: 24
+          package-manager-cache: false
+      - run: node .github/scripts/check-prompt-sync.mjs