fidelity detection fix (part 1 - see below)

In early July fidelity changed the casing on the CSV headers. This broke
the file detection (Schwab/Fidelity) because zfin was doing a case
sensitive match on these headers. This quick fix addresses this problem,
and a wider fix to make detection less fragile will follow shortly.

src/brokerage/fidelity.zig

@@ -81,11 +81,14 @@ pub fn parseCsv(allocator: std.mem.Allocator, data: []const u8) ![]BrokeragePosi
 
     var lines = std.mem.splitScalar(u8, content, '\n');
 
-    // Validate header row
+    // Validate header row. Case-insensitive: Fidelity switched the export
+    // header from Title Case to sentence case ("Account number,Account
+    // name,..."). The column order is unchanged, so the positional parsing
+    // below still holds; only this guard needed to loosen.
     const header_line = lines.next() orelse return error.EmptyFile;
     const header_trimmed = std.mem.trimEnd(u8, header_line, &.{ '\r', ' ' });
     if (header_trimmed.len == 0) return error.EmptyFile;
-    if (!std.mem.startsWith(u8, header_trimmed, "Account Number")) {
+    if (!std.ascii.startsWithIgnoreCase(header_trimmed, "Account Number")) {
         return error.UnexpectedHeader;
     }
 
@@ -247,3 +250,36 @@ test "parseCsv cash account type is not cash position" {
     try std.testing.expect(!positions[0].is_cash);
     try std.testing.expectApproxEqAbs(@as(f64, 190), positions[0].quantity.?, 0.01);
 }
+
+test "parseCsv accepts Fidelity's lowercase (sentence-case) header" {
+    // Regression: Fidelity switched the export header from Title Case to
+    // sentence case ("Account number,Account name,...,Last price,...,Cost
+    // basis total,Average cost basis,Type"). Column order is unchanged, so
+    // positional parsing must still work. The trailing comma after the Type
+    // value and the blank-line-separated legal footer mirror the real export.
+    const csv =
+        "Account number,Account name,Symbol,Description,Quantity,Last price,Last price change,Current value,Today's gain/loss dollar,Today's gain/loss percent,Total gain/loss dollar,Total gain/loss percent,Percent of account,Cost basis total,Average cost basis,Type\n" ++
+        "Z123,Individual - TOD,FZFXX**,HELD IN MONEY MARKET,,,,$24.03,,,,,0.12%,,,Cash,\n" ++
+        "Z123,Individual - TOD,AAPL,APPLE INC,100,$150.00,-$2.00,$15000.00,-$200.00,-1.3%,+$5000.00,+50%,99.88%,$10000.00,$100.00,Margin,\n" ++
+        "\n" ++
+        "\"Brokerage services are provided by Fidelity Brokerage Services LLC (FBS)...\"\n";
+
+    const allocator = std.testing.allocator;
+    const positions = try parseCsv(allocator, csv);
+    defer allocator.free(positions);
+
+    try std.testing.expectEqual(@as(usize, 2), positions.len);
+
+    // Money-market row -> cash, no quantity.
+    try std.testing.expectEqualStrings("FZFXX", positions[0].symbol);
+    try std.testing.expect(positions[0].is_cash);
+    try std.testing.expect(positions[0].quantity == null);
+    try std.testing.expectApproxEqAbs(@as(f64, 24.03), positions[0].current_value.?, 0.01);
+
+    // Stock row -> positional columns still resolve correctly.
+    try std.testing.expectEqualStrings("AAPL", positions[1].symbol);
+    try std.testing.expect(!positions[1].is_cash);
+    try std.testing.expectApproxEqAbs(@as(f64, 100), positions[1].quantity.?, 0.01);
+    try std.testing.expectApproxEqAbs(@as(f64, 15000.00), positions[1].current_value.?, 0.01);
+    try std.testing.expectApproxEqAbs(@as(f64, 10000.00), positions[1].cost_basis.?, 0.01);
+}

src/commands/audit/hygiene.zig

@@ -59,9 +59,14 @@ fn detectBrokerFileKind(data: []const u8) ?BrokerFileKind {
     else
         data;
 
-    // Fidelity CSV: first line starts with "Account Number" or "Account Name"
-    if (std.mem.startsWith(u8, content, "Account Number") or
-        std.mem.startsWith(u8, content, "Account Name"))
+    // Fidelity CSV: first line starts with "Account Number"/"Account Name".
+    // Case-insensitive: Fidelity switched the export header from Title Case
+    // to sentence case ("Account number,Account name,...") and could change
+    // it again. Matching this loosely also keeps the file from falling
+    // through to the broad schwab-summary heuristic below, which would
+    // otherwise misclassify it via the "Brokerage services..." legal footer.
+    if (std.ascii.startsWithIgnoreCase(content, "Account Number") or
+        std.ascii.startsWithIgnoreCase(content, "Account Name"))
         return .fidelity_csv;
 
     // Schwab per-account CSV: starts with a quoted title line like "Positions for ..."
@@ -1077,6 +1082,20 @@ test "detectBrokerFileKind: fidelity csv with BOM" {
     try std.testing.expectEqual(BrokerFileKind.fidelity_csv, detectBrokerFileKind(fidelity_bom).?);
 }
 
+test "detectBrokerFileKind: fidelity csv with lowercase header is not misclassified as schwab" {
+    // Regression: Fidelity switched the header from Title Case to sentence
+    // case ("Account number,..."). The old case-sensitive check failed and
+    // the file fell through to the schwab-summary heuristic, which
+    // false-matched on the "Brokerage services are provided by..." legal
+    // footer plus the "$" amounts. Must classify as fidelity_csv.
+    const data =
+        "Account number,Account name,Symbol,Description,Quantity,Last price,Last price change,Current value,Today's gain/loss dollar,Today's gain/loss percent,Total gain/loss dollar,Total gain/loss percent,Percent of account,Cost basis total,Average cost basis,Type\n" ++
+        "Z123,Individual - TOD,AAPL,APPLE INC,100,$150.00,-$2.00,$15000.00,,,,,99.88%,$10000.00,$100.00,Margin,\n" ++
+        "\n" ++
+        "\"Brokerage services are provided by Fidelity Brokerage Services LLC (FBS)...\" $\n";
+    try std.testing.expectEqual(BrokerFileKind.fidelity_csv, detectBrokerFileKind(data).?);
+}
+
 test "detectBrokerFileKind: schwab csv" {
     const schwab_header = "\"Positions for account Roth IRA ...1234 as of\"";
     try std.testing.expectEqual(BrokerFileKind.schwab_csv, detectBrokerFileKind(schwab_header).?);