diff --git a/src/protocol.zig b/src/protocol.zig
index dee7524..8b2610a 100644
--- a/src/protocol.zig
+++ b/src/protocol.zig
@@ -2355,3 +2355,162 @@ test "entries round trip and are independently owned" {
     const payload = try encodeEntries(allocator, &entries);
     defer allocator.free(payload);
 
+    const owned = try decodeEntries(allocator, payload);
+    defer freeOwnedEntries(allocator, owned);
+
+    try std.testing.expectEqual(@as(usize, 2), owned.len);
+    try std.testing.expectEqualStrings("a", owned[0].key);
+    try std.testing.expectEqualStrings("1", owned[0].value);
+    try std.testing.expectEqualStrings("b", owned[1].key);
+    try std.testing.expectEqualStrings("2", owned[1].value);
+}
+
+test "empty entry list round trips" {
+    const allocator = std.testing.allocator;
+    const payload = try encodeEntries(allocator, &[_]dbmod.Entry{});
+    defer allocator.free(payload);
+    const owned = try decodeEntries(allocator, payload);
+    defer freeOwnedEntries(allocator, owned);
+    try std.testing.expectEqual(@as(usize, 0), owned.len);
+}
+
+test "batch ops round trip put and delete" {
+    const allocator = std.testing.allocator;
+    const ops = [_]BatchOp{
+        .{ .put = .{ .key = "a", .value = "1" } },
+        .{ .del = "b" },
+    };
+    const payload = try encodeBatch(allocator, &ops);
+    defer allocator.free(payload);
+
+    const decoded = try decodeBatch(allocator, payload);
+    defer allocator.free(decoded);
+
+    try std.testing.expectEqual(@as(usize, 2), decoded.len);
+    try std.testing.expectEqualStrings("a", decoded[0].put.key);
+    try std.testing.expectEqualStrings("1", decoded[0].put.value);
+    try std.testing.expectEqualStrings("b", decoded[1].del);
+}
+
+test "decodeBatch rejects an unknown op kind" {
+    const allocator = std.testing.allocator;
+    var buf = std.ArrayList(u8).init(allocator);
+    defer buf.deinit();
+    const w = encode.ByteWriter.init(&buf);
+    try w.putU32(1);
+    try w.byte(9);
+    try std.testing.expectError(error.Malformed, decodeBatch(allocator, buf.items));
+}
+
+test "stats round trip preserves all fields including per-level detail" {
+    const allocator = std.testing.allocator;
+    var stats = dbmod.Stats{};
+    stats.memtableEntries = 3;
+    stats.memtableBytes = 128;
+    stats.sstableCount = 2;
+    stats.liveEntries = 100;
+    stats.physicalBytes = 4096;
+    stats.cacheHits = 10;
+    stats.cacheMisses = 4;
+    stats.nextSeq = 55;
+    stats.levels[0] = .{ .tables = 1, .entries = 50, .physicalBytes = 2048 };
+    stats.levels[3] = .{ .tables = 2, .entries = 50, .physicalBytes = 2048 };
+
+    const payload = try encodeStats(allocator, stats);
+    defer allocator.free(payload);
+    const decoded = try decodeStats(payload);
+
+    try std.testing.expectEqual(stats.memtableEntries, decoded.memtableEntries);
+    try std.testing.expectEqual(stats.nextSeq, decoded.nextSeq);
+    try std.testing.expectEqual(stats.levels[0].tables, decoded.levels[0].tables);
+    try std.testing.expectEqual(stats.levels[3].entries, decoded.levels[3].entries);
+    try std.testing.expectEqual(@as(f64, decoded.cacheHitRate()), decoded.cacheHitRate());
+}
+
+test "table select args round trip with a non-empty expr" {
+    const allocator = std.testing.allocator;
+    const payload = try encodeTableSelect(allocator, "users", "city eq s:warsaw", 0, 0, &.{});
+    defer allocator.free(payload);
+    const args = try decodeTableSelect(allocator, payload);
+    defer allocator.free(args.orderBy);
+    try std.testing.expectEqualStrings("users", args.table);
+    try std.testing.expectEqualStrings("city eq s:warsaw", args.exprText);
+    try std.testing.expectEqual(@as(u32, 0), args.offset);
+    try std.testing.expectEqual(@as(u32, 0), args.limit);
+    try std.testing.expectEqual(@as(usize, 0), args.orderBy.len);
+}
+
+test "table select args round trip with an empty expr means select all" {
+    const allocator = std.testing.allocator;
+    const payload = try encodeTableSelect(allocator, "users", "", 0, 0, &.{});
+    defer allocator.free(payload);
+    const args = try decodeTableSelect(allocator, payload);
+    defer allocator.free(args.orderBy);
+    try std.testing.expectEqualStrings("users", args.table);
+    try std.testing.expectEqualStrings("", args.exprText);
+}
+
+test "table select args round trip with a page window" {
+    const allocator = std.testing.allocator;
+    const payload = try encodeTableSelect(allocator, "users", "age gt i:10", 5, 3, &.{});
+    defer allocator.free(payload);
+    const args = try decodeTableSelect(allocator, payload);
+    defer allocator.free(args.orderBy);
+    try std.testing.expectEqualStrings("users", args.table);
+    try std.testing.expectEqualStrings("age gt i:10", args.exprText);
+    try std.testing.expectEqual(@as(u32, 5), args.offset);
+    try std.testing.expectEqual(@as(u32, 3), args.limit);
+}
+
+test "table select args round trip with an ascending order-by" {
+    const allocator = std.testing.allocator;
+    const payload = try encodeTableSelect(allocator, "users", "", 0, 0, &.{.{ .field = "age" }});
+    defer allocator.free(payload);
+    const args = try decodeTableSelect(allocator, payload);
+    defer allocator.free(args.orderBy);
+    try std.testing.expectEqual(@as(usize, 1), args.orderBy.len);
+    try std.testing.expectEqualStrings("age", args.orderBy[0].field);
+    try std.testing.expectEqual(false, args.orderBy[0].descending);
+}
+
+test "table select args round trip with a descending order-by, page, and expr all together" {
+    const allocator = std.testing.allocator;
+    const payload = try encodeTableSelect(allocator, "users", "city eq s:warsaw", 2, 5, &.{.{ .field = "score", .descending = true }});
+    defer allocator.free(payload);
+    const args = try decodeTableSelect(allocator, payload);
+    defer allocator.free(args.orderBy);
+    try std.testing.expectEqualStrings("users", args.table);
+    try std.testing.expectEqualStrings("city eq s:warsaw", args.exprText);
+    try std.testing.expectEqual(@as(u32, 2), args.offset);
+    try std.testing.expectEqual(@as(u32, 5), args.limit);
+    try std.testing.expectEqualStrings("score", args.orderBy[0].field);
+    try std.testing.expectEqual(true, args.orderBy[0].descending);
+}
+
+test "table select args round trip with two order-by columns in given order" {
+    const allocator = std.testing.allocator;
+    const payload = try encodeTableSelect(allocator, "users", "", 0, 0, &.{ .{ .field = "city" }, .{ .field = "score", .descending = true } });
+    defer allocator.free(payload);
+    const args = try decodeTableSelect(allocator, payload);
+    defer allocator.free(args.orderBy);
+    try std.testing.expectEqual(@as(usize, 2), args.orderBy.len);
+    try std.testing.expectEqualStrings("city", args.orderBy[0].field);
+    try std.testing.expectEqual(false, args.orderBy[0].descending);
+    try std.testing.expectEqualStrings("score", args.orderBy[1].field);
+    try std.testing.expectEqual(true, args.orderBy[1].descending);
+}
+
+test "decodeTableSelect rejects an order-by count claiming more columns than were actually encoded" {
+    const allocator = std.testing.allocator;
+    const payload = try encodeTableSelect(allocator, "users", "", 0, 0, &.{.{ .field = "age" }});
+    defer allocator.free(payload);
+    // The count byte sits right after the two u32 page fields: 4 (table
+    // len prefix) + 5 ("users") + 4 (offset) + 4 (limit).
+    const countBytePos = 4 + 5 + 4 + 4;
+    try std.testing.expectEqual(@as(u8, 1), payload[countBytePos]);
+    var corrupted = try allocator.dupe(u8, payload);
+    defer allocator.free(corrupted);
+    corrupted[countBytePos] = 200;
+    try std.testing.expectError(error.Malformed, decodeTableSelect(allocator, corrupted));
+}
+