fix(expenses): improve receipt amount extraction and vendor naming

- Remove card brands (VISA/MC/Amex) from _SKIP_LINE_RE so card-terminal
  lines like "VISA USD$ 36.78" are no longer skipped
- Replace bottom-50% scan with full-text max scan (Pass 2): scans every
  line in the receipt and returns the largest dollar amount, correctly
  handling display-style receipts that show the charge at the top with
  no label (e.g. LAYAL CAFE $40.10 before the item list)
- Update vendor LLM prompt to ask the model to correct OCR garbling
  (e.g. "NeDonald's" → "McDonald's") and detect bank statements
- Add 4 new tests covering top-amount, card-terminal, max-beats-items,
  and change-exclusion scenarios (71 tests, all passing)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

agent_service/agents/expenses_agent.py

@@ -21,11 +21,11 @@ _TOTAL_RE = re.compile(
     re.IGNORECASE,
 )
 
-# Lines printed AFTER the total (change given, tip, etc.) — skip these
-# when doing the bottom-of-receipt scan so we don't mistake them for the total.
+# Lines that should never be treated as the total — change given back,
+# tip added after the fact, etc.  Card-brand lines like "VISA USD$ 36.78"
+# are intentionally NOT listed here: the amount on those lines IS the charge.
 _SKIP_LINE_RE = re.compile(
-    r'\b(?:change|cash\s*(?:paid|tendered)?|tip|gratuity|approved|'
-    r'auth(?:orized)?|visa|mastercard|amex|discover)\b',
+    r'\b(?:change|cash\s*(?:paid|tendered)?|tip|gratuity)\b',
     re.IGNORECASE,
 )
 
@@ -41,10 +41,15 @@ def _extract_amount_from_text(text: str) -> float:
     """Return the final total from OCR receipt text, or 0.0 if not found.
 
     Pass 1 — labeled total: 'Total:', 'Grand Total:', 'Amount Due:', etc.
-    Pass 2 — bottom scan: reads lines from the bottom of the last 50% of text,
-             skipping change/cash/tip lines.  Handles cases where Tesseract
-             garbled 'TOTAL' (e.g. 'T0TAL') or placed the amount on its own
-             line below the label.
+    Pass 2 — full-text maximum: scan every line for a dollar amount (skipping
+             change/tip lines) and return the largest value found.  This handles:
+             • display-style receipts that show the charge at the top with no
+               label (e.g. LAYAL CAFE — "$40.10" printed before the item list)
+             • card-terminal printouts with lines like "VISA USD$ 36.78" that
+               carry no 'Total' keyword
+             The maximum heuristic works because the receipt total is always
+             ≥ any individual item price; Pass 1 (labeled total) catches the
+             rare cases where a discount makes the total less than a line item.
     """
     if not text:
         return 0.0
@@ -60,20 +65,21 @@ def _extract_amount_from_text(text: str) -> float:
         except ValueError:
             pass
 
-    # Pass 2: bottom-of-receipt line scan
-    # Only search the bottom half so item prices (middle section) are excluded
-    bottom = text[max(0, int(len(text) * 0.5)):]
-    for line in reversed(bottom.splitlines()):
+    # Pass 2: maximum dollar amount across the full text
+    best = 0.0
+    for line in text.splitlines():
         if _SKIP_LINE_RE.search(line):
             continue
         m = _ANY_DOLLAR_RE.search(line)
         if m:
             try:
                 val = float(m.group(1).replace(',', ''))
-                if val > 0:
-                    return val
+                if val > best:
+                    best = val
             except ValueError:
                 pass
+    if best > 0:
+        return best
 
     return 0.0
 
@@ -462,13 +468,18 @@ class ExpensesAgent(BaseAgent):
             excerpt = stripped[:600]
             prompt = (
                 'Return ONLY valid JSON with exactly two keys:\n'
-                '"vendor": the store or restaurant name, copied exactly from the '
-                'first 1-3 lines of the receipt. Use "" if no clear name.\n'
+                '"vendor": the merchant or store name from the receipt header. '
+                'OCR often garbles text — use your knowledge to correct obvious '
+                'errors (e.g. "NeDonald\'s" → "McDonald\'s", "TN-N-QUT" → '
+                '"IN-N-OUT Burger", "Subwey" → "Subway", "LRYAL" → "LAYAL"). '
+                'If this looks like a bank or credit-card statement listing '
+                'multiple transactions rather than a single merchant receipt, '
+                'use "". Use "" if no clear business name is visible.\n'
                 f'"product_name": the single best match from [{product_list}] '
                 'based on the type of business (restaurant→Meals, gas station→Fuel, '
                 'hotel→Hotel, airline/transit→Transport, office store→Office Supplies). '
                 'Use "" if none fit.\n\n'
-                f'Receipt:\n{excerpt}\n\nJSON only:'
+                f'Receipt text:\n{excerpt}\n\nJSON only:'
             )
         elif product_list:
             # OCR failed — guess category from filename only