Serve _data/api JSON in dev server

app.js fetches /_data/api/commands.json and patterns.json, but those are
build artifacts written into site/public/_data/ by scripts/build.js. The
plain `astro dev` server never runs that build, so the homepage 404'd on
both in dev.

Extract generateApiData into scripts/lib/api-data.js (shared by the build
and a new scripts/gen-dev-api.mjs prebuild), and run the prebuild before
astro dev so `bun run dev` serves the same payloads as production.
site/public/_data/ stays gitignored.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

scripts/lib/api-data.js

@@ -0,0 +1,98 @@
+import path from 'path';
+import fs from 'fs';
+
+/**
+ * Generate static API data for Cloudflare Pages deployment.
+ * Pre-builds all API responses as JSON files so they can be served
+ * as static assets via _redirects rewrites (no function invocations needed).
+ *
+ * Shared by the production build (scripts/build.js, writing into site/public/)
+ * and the dev prebuild (scripts/gen-dev-api.mjs) so `bun run dev` serves the
+ * same payloads `app.js` fetches in production. `outDir` is the directory that
+ * gets a `_data/api/` tree; `rootDir` is the repo root.
+ */
+export function generateApiData(outDir, skills, patterns, rootDir) {
+  const apiDir = path.join(outDir, '_data', 'api');
+  fs.mkdirSync(apiDir, { recursive: true });
+
+  // skills.json
+  const skillsData = skills.map(s => ({
+    id: path.basename(path.dirname(s.filePath)),
+    name: s.name,
+    description: s.description,
+    userInvocable: s.userInvocable,
+  }));
+  fs.writeFileSync(path.join(apiDir, 'skills.json'), JSON.stringify(skillsData));
+
+  // commands.json - after v3.0 consolidation, commands are sub-commands of
+  // /impeccable. Load them from command-metadata.json and include the root
+  // impeccable skill itself so UI surfaces like the cheatsheet can list them.
+  // Each entry also picks up a short `tagline` from its editorial file
+  // (site/content/skills/<id>.md) when one exists. Taglines are used by UI
+  // surfaces that need a human-friendly one-liner, while `description` stays
+  // optimized for auto-trigger keyword matching in the AI harness.
+  const readTagline = (id) => {
+    const editorialPath = path.join(rootDir, 'site/content/skills', `${id}.md`);
+    if (!fs.existsSync(editorialPath)) return null;
+    const raw = fs.readFileSync(editorialPath, 'utf-8');
+    const match = raw.match(/^---\n([\s\S]*?)\n---/);
+    if (!match) return null;
+    const taglineMatch = match[1].match(/tagline:\s*"([^"]+)"/);
+    return taglineMatch ? taglineMatch[1] : null;
+  };
+
+  const metadataPath = path.join(rootDir, 'skill/scripts/command-metadata.json');
+  if (!fs.existsSync(metadataPath)) {
+    throw new Error(`command-metadata.json is missing at ${metadataPath}. This file is required to generate the commands API.`);
+  }
+  const impeccable = skills.find(s => s.name === 'impeccable');
+  if (!impeccable) {
+    throw new Error('impeccable skill not found at skill/SKILL.src.md. The build system expects exactly one skill at that path.');
+  }
+
+  const metadata = JSON.parse(fs.readFileSync(metadataPath, 'utf-8'));
+  const commandsData = [
+    {
+      id: 'impeccable',
+      name: 'impeccable',
+      description: impeccable.description,
+      tagline: readTagline('impeccable'),
+      userInvocable: true,
+    },
+    ...Object.entries(metadata).map(([id, meta]) => ({
+      id,
+      name: id,
+      description: meta.description,
+      tagline: readTagline(id),
+      userInvocable: true,
+    })),
+  ];
+  fs.writeFileSync(path.join(apiDir, 'commands.json'), JSON.stringify(commandsData));
+
+  // patterns.json
+  fs.writeFileSync(path.join(apiDir, 'patterns.json'), JSON.stringify(patterns));
+
+  // version.json - a tiny endpoint the installed skill polls on boot
+  // (skill/scripts/context.mjs) to nudge users toward `npx impeccable skills
+  // update`. Kept deliberately small so the boot-time check is cheap, unlike
+  // the full bundle download `skills check` performs. The skills version is
+  // the canonical one in the Claude plugin manifest.
+  const pluginManifestPath = path.join(rootDir, '.claude-plugin/plugin.json');
+  const skillsVersion = JSON.parse(fs.readFileSync(pluginManifestPath, 'utf-8')).version;
+  fs.writeFileSync(path.join(apiDir, 'version.json'), JSON.stringify({ skills: skillsVersion }));
+
+  // command-source/{id}.json (one per skill)
+  const cmdSourceDir = path.join(apiDir, 'command-source');
+  fs.mkdirSync(cmdSourceDir, { recursive: true });
+  for (const skill of skills) {
+    const id = path.basename(path.dirname(skill.filePath));
+    const content = fs.readFileSync(skill.filePath, 'utf-8');
+    fs.writeFileSync(
+      path.join(cmdSourceDir, `${id}.json`),
+      JSON.stringify({ content })
+    );
+  }
+
+  const skillWord = skillsData.length === 1 ? 'skill' : 'skills';
+  console.log(`✓ Generated static API data (${skillsData.length} ${skillWord}, ${commandsData.length} commands)`);
+}