src/utils/csvAutoDetect.ts

@@ -707,6 +707,37 @@ function detectBalanceColumns(
  * labelling its amount column `Détail du montant` therefore cannot end up with
  * its amounts in the description.
  */
+/**
+ * Does this column behave like an enumeration rather than free text?
+ *
+ * A label alone is not enough to pick the description: Tangerine exports
+ * `Date,Transaction,Name,Memo,Amount`, where `Transaction` holds DEBIT/CREDIT
+ * and `Name` holds the merchant. Honouring the label there moves the merchant
+ * out of the description and kills keyword categorisation.
+ *
+ * Cardinality separates the two — a description repeats almost nothing, an enum
+ * repeats almost everything. Average length does NOT: `Note` and `Libellé` are
+ * both short, and vetoing on length would reject legitimate columns.
+ */
+function looksLikeEnumColumn(rows: string[][], col: number): boolean {
+  const distinct = new Set<string>();
+  let filled = 0;
+
+  for (const row of rows) {
+    const cell = row[col]?.trim();
+    if (!cell) continue;
+    filled++;
+    distinct.add(cell.toLowerCase());
+  }
+
+  // A labelled but entirely empty column is never the description either.
+  if (filled === 0) return true;
+  // Too few rows to read anything into the cardinality.
+  if (filled < 4) return false;
+
+  return distinct.size <= Math.max(2, Math.floor(filled / 4));
+}
+
 function detectDescriptionColumn(
   rows: string[][],
   colCount: number,
@@ -719,7 +750,8 @@ function detectDescriptionColumn(
     preferred !== null &&
     preferred < colCount &&
     preferred !== dateCol &&
-    !numericCols.has(preferred)
+    !numericCols.has(preferred) &&
+    !looksLikeEnumColumn(rows, preferred)
   ) {
     return preferred;
   }
@@ -779,6 +811,26 @@ type AmountModeResult = SingleAmountResult | DebitCreditResult;
  * nothing numeric is dropped here and the generic path decides, exactly like a
  * mismatched label.
  */
+/**
+ * The first sparse-complementary pair among the candidates, in column order, or
+ * null. Extracted from `detectAmountMode` so a bank signature can be arbitrated
+ * AGAINST the pair the shape scan would have found, instead of short-circuiting
+ * a scan that never ran.
+ */
+function findSparseComplementaryPair(
+  rows: string[][],
+  amountCandidates: number[]
+): [number, number] | null {
+  for (let a = 0; a < amountCandidates.length; a++) {
+    for (let b = a + 1; b < amountCandidates.length; b++) {
+      const colA = amountCandidates[a];
+      const colB = amountCandidates[b];
+      if (isSparseComplementary(rows, colA, colB)) return [colA, colB];
+    }
+  }
+  return null;
+}
+
 function detectAmountMode(
   rows: string[][],
   amountCandidates: number[],
@@ -787,6 +839,8 @@ function detectAmountMode(
 ): AmountModeResult | null {
   if (amountCandidates.length === 0) return null;
 
+  const pair = findSparseComplementaryPair(rows, amountCandidates);
+
   if (signature) {
     const { debit, credit, amount } = signature.roles;
     if (
@@ -797,7 +851,17 @@ function detectAmountMode(
     ) {
       return { mode: "debit_credit", debitCol: debit, creditCol: credit };
     }
-    if (amount !== null && amountCandidates.includes(amount)) {
+    // A signature's SINGLE amount column may not silently displace a genuine
+    // debit/credit pair it has no part in. RBC needs the override — its
+    // near-empty `Cheque Number` really is sparse-complementary with `CAD$` —
+    // but there the pair contains the declared amount column. On a
+    // `Date;Description;Débit;Crédit;Montant;Solde` file the pair does not, and
+    // taking `Montant` unsigned imported every deposit as an expense.
+    if (
+      amount !== null &&
+      amountCandidates.includes(amount) &&
+      (!pair || pair.includes(amount))
+    ) {
       return detectSingleAmount(rows, amount);
     }
   }
@@ -806,16 +870,8 @@ function detectAmountMode(
     return detectSingleAmount(rows, amountCandidates[0]);
   }
 
-  // Check for sparse-complementary pair (debit/credit pattern)
-  for (let a = 0; a < amountCandidates.length; a++) {
-    for (let b = a + 1; b < amountCandidates.length; b++) {
-      const colA = amountCandidates[a];
-      const colB = amountCandidates[b];
-
-      if (isSparseComplementary(rows, colA, colB)) {
-        return orderDebitCredit(colA, colB, lexical);
-      }
-    }
+  if (pair) {
+    return orderDebitCredit(pair[0], pair[1], lexical);
   }
 
   // No complementary pair found — the labelled amount column if there is one,