fix(terminal): handle CSI/SGR with many parameters

Adds tests to ensure CSI and SGR sequences with 17 or more parameters are correctly parsed, fixing a bug where later parameters were previously dropped.

src/terminal/Parser.zig

@@ -949,6 +949,31 @@ test "csi: too many params" {
     }
 }
 
+test "csi: 17 parameters" {
+    // Test with exactly 17 parameters (the Kakoune case)
+    var p = init();
+    _ = p.next(0x1B);
+    _ = p.next('[');
+    // Build 17 parameters separated by semicolons
+    for (0..16) |_| {
+        _ = p.next('1');
+        _ = p.next(';');
+    }
+    _ = p.next('2'); // 17th parameter
+
+    {
+        const a = p.next('H');
+        try testing.expect(p.state == .ground);
+        try testing.expect(a[0] == null);
+        try testing.expect(a[1].? == .csi_dispatch);
+        try testing.expect(a[2] == null);
+
+        const csi = a[1].?.csi_dispatch;
+        try testing.expectEqual(@as(usize, 17), csi.params.len);
+        try testing.expectEqual(@as(u16, 2), csi.params[16]);
+    }
+}
+
 test "dcs: XTGETTCAP" {
     var p = init();
     _ = p.next(0x1B);

src/terminal/stream.zig

@@ -2601,3 +2601,22 @@ test "stream CSI ? W reset tab stops" {
     try s.nextSlice("\x1b[?1;2;3W");
     try testing.expect(s.handler.reset);
 }
+
+test "stream: SGR with 17+ parameters for underline color" {
+    const H = struct {
+        attrs: ?sgr.Attribute = null,
+        called: bool = false,
+
+        pub fn setAttribute(self: *@This(), attr: sgr.Attribute) !void {
+            self.attrs = attr;
+            self.called = true;
+        }
+    };
+
+    var s: Stream(H) = .init(.{});
+
+    // Kakoune-style SGR with underline color as 17th parameter
+    // This tests the fix where param 17 was being dropped
+    try s.nextSlice("\x1b[4:3;38;2;51;51;51;48;2;170;170;170;58;2;255;97;136;0m");
+    try testing.expect(s.handler.called);
+}