Build hn-reader: keyboard-driven Hacker News reader

Vite/React + shadcn/ui frontend with Superhuman-style keyboard nav
(j/k/o/v/e/s/u, feed switching, localStorage caching for instant
loads) backed by an Express API that polls the HN Firebase API into
Postgres and serves cached feeds/comments. Instrumented with
OpenTelemetry (traces/metrics/logs via OTLP/HTTP).

server/index.js

@@ -0,0 +1,134 @@
+require('dotenv').config({ quiet: true })
+require('./otel') // must load before express/pg are used, for auto-instrumentation
+
+const path = require('path')
+const express = require('express')
+const cors = require('cors')
+const { pool } = require('./db')
+const { log } = require('./otel')
+const { FEEDS, syncAll, fetchCommentsTree } = require('./hn')
+
+const PORT = Number(process.env.PORT || 3012)
+const SYNC_INTERVAL_MS = 5 * 60 * 1000
+
+const app = express()
+app.use(cors())
+app.use(express.json())
+
+app.get('/api/health', async (_req, res) => {
+  try {
+    await pool.query('SELECT 1')
+    res.json({ ok: true })
+  } catch (err) {
+    res.status(503).json({ ok: false, error: String(err) })
+  }
+})
+
+app.get('/api/feed/:feed', async (req, res) => {
+  const { feed } = req.params
+  if (!FEEDS[feed]) return res.status(404).json({ error: 'unknown feed' })
+
+  const limit = Math.min(Number(req.query.limit) || 100, 100)
+  const includeArchived = req.query.includeArchived === 'true'
+
+  try {
+    const { rows } = await pool.query(
+      `SELECT s.id, s.type, s.title, s.url, s.domain, s.by_user, s.score, s.descendants,
+              s.story_text, s.hn_created_at, fi.rank,
+              COALESCE(st.read, false) AS read,
+              COALESCE(st.starred, false) AS starred,
+              COALESCE(st.archived, false) AS archived
+       FROM feed_items fi
+       JOIN stories s ON s.id = fi.story_id
+       LEFT JOIN story_state st ON st.story_id = s.id
+       WHERE fi.feed = $1 ${includeArchived ? '' : 'AND COALESCE(st.archived, false) = false'}
+       ORDER BY fi.rank ASC
+       LIMIT $2`,
+      [feed, limit]
+    )
+    res.json({ feed, items: rows })
+  } catch (err) {
+    log('ERROR', 'feed query failed', { feed, error: String(err) })
+    res.status(500).json({ error: 'internal error' })
+  }
+})
+
+app.get('/api/story/:id', async (req, res) => {
+  const id = Number(req.params.id)
+  try {
+    const { rows } = await pool.query(
+      `SELECT s.*, COALESCE(st.read, false) AS read,
+              COALESCE(st.starred, false) AS starred,
+              COALESCE(st.archived, false) AS archived
+       FROM stories s
+       LEFT JOIN story_state st ON st.story_id = s.id
+       WHERE s.id = $1`,
+      [id]
+    )
+    if (!rows.length) return res.status(404).json({ error: 'not found' })
+    res.json(rows[0])
+  } catch (err) {
+    log('ERROR', 'story query failed', { id, error: String(err) })
+    res.status(500).json({ error: 'internal error' })
+  }
+})
+
+app.get('/api/story/:id/comments', async (req, res) => {
+  const id = Number(req.params.id)
+  try {
+    const comments = await fetchCommentsTree(id)
+    res.json({ id, comments })
+  } catch (err) {
+    log('ERROR', 'comments fetch failed', { id, error: String(err) })
+    res.status(502).json({ error: 'failed to fetch comments' })
+  }
+})
+
+app.post('/api/story/:id/state', async (req, res) => {
+  const id = Number(req.params.id)
+  const { read, starred, archived } = req.body || {}
+  try {
+    const { rows } = await pool.query(
+      `INSERT INTO story_state (story_id, read, starred, archived, read_at, updated_at)
+       VALUES ($1, COALESCE($2, false), COALESCE($3, false), COALESCE($4, false),
+               CASE WHEN $2 THEN now() ELSE NULL END, now())
+       ON CONFLICT (story_id) DO UPDATE SET
+         read = COALESCE($2, story_state.read),
+         starred = COALESCE($3, story_state.starred),
+         archived = COALESCE($4, story_state.archived),
+         read_at = CASE WHEN COALESCE($2, story_state.read) AND NOT story_state.read
+                        THEN now() ELSE story_state.read_at END,
+         updated_at = now()
+       RETURNING *`,
+      [id, read, starred, archived]
+    )
+    res.json(rows[0])
+  } catch (err) {
+    log('ERROR', 'state update failed', { id, error: String(err) })
+    res.status(500).json({ error: 'internal error' })
+  }
+})
+
+app.post('/api/sync', async (_req, res) => {
+  syncAll().catch((err) => log('ERROR', 'manual sync failed', { error: String(err) }))
+  res.json({ ok: true, started: true })
+})
+
+// Serve the built frontend in production.
+const distDir = path.join(__dirname, '..', 'dist')
+app.use(express.static(distDir))
+app.get(/^(?!\/api).*/, (_req, res) => {
+  res.sendFile(path.join(distDir, 'index.html'))
+})
+
+app.listen(PORT, () => {
+  log('INFO', 'hn-reader-api listening', { port: PORT })
+})
+
+syncAll()
+  .then(() => log('INFO', 'initial sync complete'))
+  .catch((err) => log('ERROR', 'initial sync failed', { error: String(err) }))
+
+setInterval(() => {
+  syncAll().catch((err) => log('ERROR', 'periodic sync failed', { error: String(err) }))
+}, SYNC_INTERVAL_MS)