diff --git a/CHANGELOG.md b/CHANGELOG.md
index 79f62c1..63dbac9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,13 @@
 # Changelog
 
+## 0.43.0 - 2025-10-21
+
+### Enhancements
+- Made `Unset` a fully-supported variant of `SystemCode` and `ErrorCode`
+
+### Breaking changes
+- Removed `mode` parameter in `Historical::MetadataGetCost()`
+
 ## 0.42.0 - 2025-08-19
 
 ### Enhancements
diff --git a/CMakeLists.txt b/CMakeLists.txt
index c5b72db..7cf3697 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -6,7 +6,7 @@ cmake_minimum_required(VERSION 3.24..4.0)
 
 project(
   databento
-  VERSION 0.42.0
+  VERSION 0.43.0
   LANGUAGES CXX
   DESCRIPTION "Official Databento client library"
 )
diff --git a/cmake/StandardSettings.cmake b/cmake/StandardSettings.cmake
index 3046821..5e90442 100644
--- a/cmake/StandardSettings.cmake
+++ b/cmake/StandardSettings.cmake
@@ -43,7 +43,7 @@ option(${PROJECT_NAME_UPPERCASE}_ENABLE_TSAN "Enable thread sanitizer." OFF)
 option(${PROJECT_NAME_UPPERCASE}_ENABLE_UBSAN "Enable undefined behavior sanitizer." OFF)
 
 #
-# Miscelanious options
+# Miscellaneous options
 #
 
 # Generate compile_commands.json for clang based tools
diff --git a/cmake/Utils.cmake b/cmake/Utils.cmake
index bfdd8f3..d359f9b 100644
--- a/cmake/Utils.cmake
+++ b/cmake/Utils.cmake
@@ -10,7 +10,7 @@ function(verbose_message content)
 endfunction()
 
 #
-# Add a target for formating the project using `clang-format` (i.e: cmake --build build --target clang-format)
+# Add a target for formatting the project using `clang-format` (i.e: cmake --build build --target clang-format)
 #
 
 function(add_clang_format_target)
diff --git a/include/databento/dbn.hpp b/include/databento/dbn.hpp
index b349848..4aac19f 100644
--- a/include/databento/dbn.hpp
+++ b/include/databento/dbn.hpp
@@ -76,7 +76,7 @@ struct Metadata {
   // This method is useful when working with a historical request over a single
   // day or in other situations where you're sure the mappings don't change
   // during the time range of the request. Otherwise, `SymbolMap()` is
-  // recommmended.
+  // recommended.
   PitSymbolMap CreateSymbolMapForDate(date::year_month_day date) const;
   // Creates a symbology mapping from instrument ID and date to text symbol.
   TsSymbolMap CreateSymbolMap() const;
diff --git a/include/databento/detail/buffer.hpp b/include/databento/detail/buffer.hpp
index 7488342..ff9d68e 100644
--- a/include/databento/detail/buffer.hpp
+++ b/include/databento/detail/buffer.hpp
@@ -43,7 +43,7 @@ class Buffer : public IReadable, public IWritable {
   std::byte* ReadEnd() { return write_pos_; }
   const std::byte* ReadBegin() const { return read_pos_; }
   const std::byte* ReadEnd() const { return write_pos_; }
-  // Indicate how mnay bytes were read
+  // Indicate how many bytes were read
   void Consume(std::size_t length) {
     read_pos_ += length;
     if (static_cast<std::size_t>(read_pos_ - buf_.get()) > (Capacity() / 2)) {
diff --git a/include/databento/enums.hpp b/include/databento/enums.hpp
index 128bc71..dcba208 100644
--- a/include/databento/enums.hpp
+++ b/include/databento/enums.hpp
@@ -609,6 +609,8 @@ enum ErrorCode : std::uint8_t {
   InvalidSubscription = 5,
   // An error occurred in the gateway.
   InternalError = 6,
+  // No error code was specified or this record was upgraded from a version 1 struct
+  // where the code field didn't exist.
   Unset = 255,
 };
 }  // namespace error_code
@@ -630,6 +632,8 @@ enum SystemCode : std::uint8_t {
   // Signals that all records for interval-based schemas have been published for the
   // given timestamp.
   EndOfInterval = 4,
+  // No system code was specified or this record was upgraded from a version 1 struct
+  // where the code field didn't exist.
   Unset = 255,
 };
 }  // namespace system_code
diff --git a/include/databento/historical.hpp b/include/databento/historical.hpp
index 7af9f22..0c5474a 100644
--- a/include/databento/historical.hpp
+++ b/include/databento/historical.hpp
@@ -84,7 +84,7 @@ class Historical {
    * Metadata API
    */
 
-  // Retrievs a mapping of publisher name to publisher ID.
+  // Retrieves a mapping of publisher name to publisher ID.
   std::vector<PublisherDetail> MetadataListPublishers();
   std::vector<std::string> MetadataListDatasets();
   std::vector<std::string> MetadataListDatasets(const DateRange& date_range);
@@ -139,11 +139,11 @@ class Historical {
   double MetadataGetCost(const std::string& dataset,
                          const DateTimeRange<UnixNanos>& datetime_range,
                          const std::vector<std::string>& symbols, Schema schema,
-                         FeedMode mode, SType stype_in, std::uint64_t limit);
+                         SType stype_in, std::uint64_t limit);
   double MetadataGetCost(const std::string& dataset,
                          const DateTimeRange<std::string>& datetime_range,
                          const std::vector<std::string>& symbols, Schema schema,
-                         FeedMode mode, SType stype_in, std::uint64_t limit);
+                         SType stype_in, std::uint64_t limit);
 
   /*
    * Symbology API
diff --git a/pkg/PKGBUILD b/pkg/PKGBUILD
index 7a1c703..a35bf8a 100644
--- a/pkg/PKGBUILD
+++ b/pkg/PKGBUILD
@@ -1,7 +1,7 @@
 # Maintainer: Databento <support@databento.com>
 _pkgname=databento-cpp
 pkgname=databento-cpp-git
-pkgver=0.42.0
+pkgver=0.43.0
 pkgrel=1
 pkgdesc="Official C++ client for Databento"
 arch=('any')
diff --git a/src/enums.cpp b/src/enums.cpp
index 65f865a..97d898a 100644
--- a/src/enums.cpp
+++ b/src/enums.cpp
@@ -776,6 +776,9 @@ const char* ToString(ErrorCode error_code) {
     case ErrorCode::InternalError: {
       return "internal_error";
     }
+    case ErrorCode::Unset: {
+      return "unset";
+    }
     default: {
       return "Unknown";
     }
@@ -798,6 +801,9 @@ const char* ToString(SystemCode system_code) {
     case SystemCode::EndOfInterval: {
       return "end_of_interval";
     }
+    case SystemCode::Unset: {
+      return "unset";
+    }
     default: {
       return "Unknown";
     }
@@ -1219,6 +1225,9 @@ ErrorCode FromString(const std::string& str) {
   if (str == "internal_error") {
     return ErrorCode::InternalError;
   }
+  if (str == "unset") {
+    return ErrorCode::Unset;
+  }
   throw InvalidArgumentError{"FromString<ErrorCode>", "str",
                              "unknown value '" + str + '\''};
 }
@@ -1239,6 +1248,9 @@ SystemCode FromString(const std::string& str) {
   if (str == "end_of_interval") {
     return SystemCode::EndOfInterval;
   }
+  if (str == "unset") {
+    return SystemCode::Unset;
+  }
   throw InvalidArgumentError{"FromString<SystemCode>", "str",
                              "unknown value '" + str + '\''};
 }
diff --git a/src/historical.cpp b/src/historical.cpp
index 9df88a0..34fe9ce 100644
--- a/src/historical.cpp
+++ b/src/historical.cpp
@@ -665,25 +665,23 @@ double Historical::MetadataGetCost(const std::string& dataset,
                                    const std::vector<std::string>& symbols,
                                    Schema schema) {
   return this->MetadataGetCost(dataset, datetime_range, symbols, schema,
-                               FeedMode::HistoricalStreaming, kDefaultSTypeIn, {});
+                               kDefaultSTypeIn, {});
 }
 double Historical::MetadataGetCost(const std::string& dataset,
                                    const DateTimeRange<std::string>& datetime_range,
                                    const std::vector<std::string>& symbols,
                                    Schema schema) {
   return this->MetadataGetCost(dataset, datetime_range, symbols, schema,
-                               FeedMode::HistoricalStreaming, kDefaultSTypeIn, {});
+                               kDefaultSTypeIn, {});
 }
 double Historical::MetadataGetCost(const std::string& dataset,
                                    const DateTimeRange<UnixNanos>& datetime_range,
                                    const std::vector<std::string>& symbols,
-                                   Schema schema, FeedMode mode, SType stype_in,
-                                   std::uint64_t limit) {
+                                   Schema schema, SType stype_in, std::uint64_t limit) {
   httplib::Params params{
       {"dataset", dataset},
       {"start", ToString(datetime_range.start)},
       {"symbols", JoinSymbolStrings(kMetadataGetCostEndpoint, symbols)},
-      {"mode", ToString(mode)},
       {"schema", ToString(schema)},
       {"stype_in", ToString(stype_in)}};
   detail::SetIfPositive(&params, "end", datetime_range.end);
@@ -693,13 +691,11 @@ double Historical::MetadataGetCost(const std::string& dataset,
 double Historical::MetadataGetCost(const std::string& dataset,
                                    const DateTimeRange<std::string>& datetime_range,
                                    const std::vector<std::string>& symbols,
-                                   Schema schema, FeedMode mode, SType stype_in,
-                                   std::uint64_t limit) {
+                                   Schema schema, SType stype_in, std::uint64_t limit) {
   httplib::Params params{
       {"dataset", dataset},
       {"start", datetime_range.start},
       {"symbols", JoinSymbolStrings(kMetadataGetCostEndpoint, symbols)},
-      {"mode", ToString(mode)},
       {"schema", ToString(schema)},
       {"stype_in", ToString(stype_in)}};
   detail::SetIfNotEmpty(&params, "end", datetime_range.end);
diff --git a/tests/src/batch_tests.cpp b/tests/src/batch_tests.cpp
index 55d6521..09260d8 100644
--- a/tests/src/batch_tests.cpp
+++ b/tests/src/batch_tests.cpp
@@ -6,7 +6,7 @@
 
 namespace databento::tests {
 TEST(BatchTests, TestBatchJobToString) {
-  const BatchJob target{"aNiD",
+  const BatchJob target{"AN_ID",
                         "USER",
                         12.39,
                         dataset::kXnasItch,
@@ -38,7 +38,7 @@ TEST(BatchTests, TestBatchJobToString) {
                         {}};
   const auto res = ToString(target);
   ASSERT_EQ(res, R"(BatchJob {
-    id = "aNiD",
+    id = "AN_ID",
     user_id = "USER",
     cost_usd = 12.39,
     dataset = "XNAS.ITCH",
diff --git a/tests/src/historical_tests.cpp b/tests/src/historical_tests.cpp
index c7361f8..19afef8 100644
--- a/tests/src/historical_tests.cpp
+++ b/tests/src/historical_tests.cpp
@@ -227,7 +227,7 @@ static const nlohmann::json kListFilesResp{
      {"hash", {}},
      {"urls",
       {{"https", "https://api.databento.com/v0/job_id/test.dbn"},
-       {"ftp", "ftp://fpt.databento.com/job_id/test.dbn"}}}},
+       {"ftp", "ftp://ftp.databento.com/job_id/test.dbn"}}}},
     {{"filename", "test_metadata.json"},
      {"size", {}},
      {"hash", {}},
@@ -552,7 +552,6 @@ TEST_F(HistoricalTests, TestMetadataGetCost_Full) {
                             {{"dataset", dataset::kGlbxMdp3},
                              {"start", "2020-06-06T00:00"},
                              {"end", "2021-03-02T00:00"},
-                             {"mode", "historical-streaming"},
                              {"symbols", "MES.OPT,EW.OPT"},
                              {"schema", "tbbo"},
                              {"stype_in", "parent"}},
@@ -562,8 +561,7 @@ TEST_F(HistoricalTests, TestMetadataGetCost_Full) {
   databento::Historical target = Client(port);
   const auto res = target.MetadataGetCost(
       dataset::kGlbxMdp3, {"2020-06-06T00:00", "2021-03-02T00:00"},
-      {"MES.OPT", "EW.OPT"}, Schema::Tbbo, FeedMode::HistoricalStreaming, SType::Parent,
-      {});
+      {"MES.OPT", "EW.OPT"}, Schema::Tbbo, SType::Parent, {});
   ASSERT_DOUBLE_EQ(res, kResp);
 }