Merge S9 (a1): slip reader — zero-API OCR

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/routes/slips.js

@@ -0,0 +1,147 @@
+'use strict';
+
+/**
+ * A1 Session 9 — POST /api/slips/parse (Slip Reader).
+ *
+ * Auth required. Accepts a base64/data-URL slip screenshot (≤4MB decoded)
+ * OR raw slip `text` (paste path + hermetic tests — skips OCR entirely).
+ * OCR is tesseract.js (self-hosted WASM, zero API spend); parsing is
+ * `slipReader.parseSlipText` — extracted values are USER-SLIP values,
+ * never written into any market cache.
+ *
+ * Rate limit: `slips:{user}:{YYYY-MM-DD}` (UTC day) — free 1/day,
+ * paid (analyst/desk) 10/day. Redis counter with an in-memory mirror so
+ * a degraded Redis still enforces the cap within this process.
+ */
+
+const express = require('express');
+const { requireAuth } = require('../middleware/auth');
+const { cacheGet, cacheSet } = require('../utils/redis');
+const slipReader = require('../services/slipReader');
+
+const router = express.Router();
+
+const MAX_IMAGE_BYTES = 4 * 1024 * 1024; // 4MB decoded
+const MAX_TEXT_CHARS = 20_000;
+const COUNTER_TTL_S = 48 * 3600; // outlives the UTC day it counts
+const MEM_MAX = 20_000;
+
+const mem = new Map(); // dayKey → count (in-memory mirror / fallback)
+
+function dailyLimit(tier) {
+  return tier === 'free' ? 1 : 10;
+}
+
+function dayKey(userId, now = new Date()) {
+  return `slips:${userId}:${now.toISOString().slice(0, 10)}`;
+}
+
+/**
+ * Consume one parse slot for the user's UTC day. Uses max(redis, memory)
+ * as the used count so neither store resetting under-counts alone.
+ */
+async function takeSlot(user, deps = {}) {
+  const get = deps.cacheGet || cacheGet;
+  const set = deps.cacheSet || cacheSet;
+  const limit = dailyLimit(user.tier || 'free');
+  const key = dayKey(user.id, deps.now);
+
+  let redisUsed = 0;
+  try {
+    const v = await get(key);
+    redisUsed = Number(v) || 0;
+  } catch { /* degraded redis → memory mirror carries it */ }
+
+  const used = Math.max(redisUsed, mem.get(key) || 0);
+  if (used >= limit) return { ok: false, used, limit };
+
+  if (mem.size > MEM_MAX) {
+    const oldest = mem.keys().next().value;
+    if (oldest !== undefined) mem.delete(oldest);
+  }
+  mem.set(key, used + 1);
+  try { await set(key, used + 1, COUNTER_TTL_S); } catch { /* best effort */ }
+  return { ok: true, used: used + 1, limit };
+}
+
+/** Decode a base64 / data-URL image field into a Buffer, or null. */
+function decodeImage(image) {
+  if (typeof image !== 'string' || !image) return null;
+  const b64 = image.replace(/^data:image\/[a-z+.-]+;base64,/i, '').replace(/\s/g, '');
+  if (!/^[A-Za-z0-9+/=]+$/.test(b64)) return null;
+  try {
+    const buf = Buffer.from(b64, 'base64');
+    return buf.length > 0 ? buf : null;
+  } catch {
+    return null;
+  }
+}
+
+router.post('/parse', requireAuth, async (req, res) => {
+  const { image, text, book } = req.body || {};
+
+  // ── Validate input BEFORE burning a daily slot ──
+  let buffer = null;
+  let rawText = null;
+  if (typeof text === 'string' && text.trim()) {
+    if (text.length > MAX_TEXT_CHARS) {
+      return res.status(400).json({ error: 'Slip text too long.' });
+    }
+    rawText = text;
+  } else if (image != null) {
+    buffer = decodeImage(image);
+    if (!buffer) {
+      return res.status(400).json({ error: 'Could not decode the image. Send base64 or a data URL.' });
+    }
+    if (buffer.length > MAX_IMAGE_BYTES) {
+      return res.status(400).json({ error: 'Image too large. 4MB max.' });
+    }
+  } else {
+    return res.status(400).json({ error: 'Send an image (base64) or slip text.' });
+  }
+
+  // ── Daily quota ──
+  const slot = await takeSlot(req.user, router.__deps || {});
+  if (!slot.ok) {
+    res.set('X-Slips-Used', String(slot.used));
+    res.set('X-Slips-Limit', String(slot.limit));
+    return res.status(429).json({
+      error: slot.limit === 1
+        ? 'One slip read per day on the free tier. Upgrade for ten.'
+        : 'Daily slip-read limit reached.',
+      used: slot.used,
+      limit: slot.limit,
+      tier: req.user.tier || 'free',
+    });
+  }
+
+  // ── OCR (image path only) ──
+  if (rawText == null) {
+    try {
+      const recognize = (router.__deps && router.__deps.recognizeImage) || slipReader.recognizeImage;
+      rawText = await recognize(buffer);
+    } catch (err) {
+      console.error('[slips] OCR failed:', err.message);
+      return res.status(503).json({ error: 'The reader could not process this image. Try again or paste the slip text.' });
+    }
+  }
+
+  // ── Parse. Values are user-slip values; unreadable fields stay null. ──
+  const result = slipReader.parseSlipText(rawText, book);
+  res.set('X-Slips-Used', String(slot.used));
+  res.set('X-Slips-Limit', String(slot.limit));
+  return res.json(result);
+});
+
+// Test hooks — injectable deps + counter reset (same pattern as scanLimit).
+router.__internals = {
+  mem,
+  dayKey,
+  takeSlot,
+  dailyLimit,
+  decodeImage,
+  resetForTests: () => mem.clear(),
+  setDeps: (deps) => { router.__deps = deps; },
+};
+
+module.exports = router;