diff --git a/crates/bindings-csharp/Codegen.Tests/fixtures/diag/snapshots/Module#FFI.verified.cs b/crates/bindings-csharp/Codegen.Tests/fixtures/diag/snapshots/Module#FFI.verified.cs
index e6df8c9e52a..07bb8a6483e 100644
--- a/crates/bindings-csharp/Codegen.Tests/fixtures/diag/snapshots/Module#FFI.verified.cs
+++ b/crates/bindings-csharp/Codegen.Tests/fixtures/diag/snapshots/Module#FFI.verified.cs
@@ -3745,7 +3745,7 @@ public static void __describe_module__(SpacetimeDB.Internal.BytesSink d) =>
 
     [UnmanagedCallersOnly(EntryPoint = "__call_reducer__")]
     public static SpacetimeDB.Internal.Errno __call_reducer__(
-        uint id,
+        int id,
         ulong sender_0,
         ulong sender_1,
         ulong sender_2,
@@ -3771,7 +3771,7 @@ SpacetimeDB.Internal.BytesSink error
 
     [UnmanagedCallersOnly(EntryPoint = "__call_procedure__")]
     public static SpacetimeDB.Internal.Errno __call_procedure__(
-        uint id,
+        int id,
         ulong sender_0,
         ulong sender_1,
         ulong sender_2,
@@ -3797,7 +3797,7 @@ SpacetimeDB.Internal.BytesSink result_sink
 
     [UnmanagedCallersOnly(EntryPoint = "__call_http_handler__")]
     public static SpacetimeDB.Internal.Errno __call_http_handler__(
-        uint id,
+        int id,
         SpacetimeDB.Timestamp timestamp,
         SpacetimeDB.Internal.BytesSource request,
         SpacetimeDB.Internal.BytesSource request_body,
@@ -3815,7 +3815,7 @@ SpacetimeDB.Internal.BytesSink response_body_sink
 
     [UnmanagedCallersOnly(EntryPoint = "__call_view__")]
     public static SpacetimeDB.Internal.Errno __call_view__(
-        uint id,
+        int id,
         ulong sender_0,
         ulong sender_1,
         ulong sender_2,
@@ -3835,7 +3835,7 @@ SpacetimeDB.Internal.BytesSink sink
 
     [UnmanagedCallersOnly(EntryPoint = "__call_view_anon__")]
     public static SpacetimeDB.Internal.Errno __call_view_anon__(
-        uint id,
+        int id,
         SpacetimeDB.Internal.BytesSource args,
         SpacetimeDB.Internal.BytesSink sink
     ) => SpacetimeDB.Internal.Module.__call_view_anon__(id, args, sink);
diff --git a/crates/bindings-csharp/Codegen.Tests/fixtures/explicitnames/snapshots/Module#FFI.verified.cs b/crates/bindings-csharp/Codegen.Tests/fixtures/explicitnames/snapshots/Module#FFI.verified.cs
index 1602df16086..e0124d76783 100644
--- a/crates/bindings-csharp/Codegen.Tests/fixtures/explicitnames/snapshots/Module#FFI.verified.cs
+++ b/crates/bindings-csharp/Codegen.Tests/fixtures/explicitnames/snapshots/Module#FFI.verified.cs
@@ -635,7 +635,7 @@ public static void __describe_module__(SpacetimeDB.Internal.BytesSink d) =>
 
     [UnmanagedCallersOnly(EntryPoint = "__call_reducer__")]
     public static SpacetimeDB.Internal.Errno __call_reducer__(
-        uint id,
+        int id,
         ulong sender_0,
         ulong sender_1,
         ulong sender_2,
@@ -661,7 +661,7 @@ SpacetimeDB.Internal.BytesSink error
 
     [UnmanagedCallersOnly(EntryPoint = "__call_procedure__")]
     public static SpacetimeDB.Internal.Errno __call_procedure__(
-        uint id,
+        int id,
         ulong sender_0,
         ulong sender_1,
         ulong sender_2,
@@ -687,7 +687,7 @@ SpacetimeDB.Internal.BytesSink result_sink
 
     [UnmanagedCallersOnly(EntryPoint = "__call_http_handler__")]
     public static SpacetimeDB.Internal.Errno __call_http_handler__(
-        uint id,
+        int id,
         SpacetimeDB.Timestamp timestamp,
         SpacetimeDB.Internal.BytesSource request,
         SpacetimeDB.Internal.BytesSource request_body,
@@ -705,7 +705,7 @@ SpacetimeDB.Internal.BytesSink response_body_sink
 
     [UnmanagedCallersOnly(EntryPoint = "__call_view__")]
     public static SpacetimeDB.Internal.Errno __call_view__(
-        uint id,
+        int id,
         ulong sender_0,
         ulong sender_1,
         ulong sender_2,
@@ -725,7 +725,7 @@ SpacetimeDB.Internal.BytesSink sink
 
     [UnmanagedCallersOnly(EntryPoint = "__call_view_anon__")]
     public static SpacetimeDB.Internal.Errno __call_view_anon__(
-        uint id,
+        int id,
         SpacetimeDB.Internal.BytesSource args,
         SpacetimeDB.Internal.BytesSink sink
     ) => SpacetimeDB.Internal.Module.__call_view_anon__(id, args, sink);
diff --git a/crates/bindings-csharp/Codegen.Tests/fixtures/server/snapshots/Module#FFI.verified.cs b/crates/bindings-csharp/Codegen.Tests/fixtures/server/snapshots/Module#FFI.verified.cs
index 1ce8d795d15..234e43c9c50 100644
--- a/crates/bindings-csharp/Codegen.Tests/fixtures/server/snapshots/Module#FFI.verified.cs
+++ b/crates/bindings-csharp/Codegen.Tests/fixtures/server/snapshots/Module#FFI.verified.cs
@@ -2563,7 +2563,7 @@ public static void __describe_module__(SpacetimeDB.Internal.BytesSink d) =>
 
     [UnmanagedCallersOnly(EntryPoint = "__call_reducer__")]
     public static SpacetimeDB.Internal.Errno __call_reducer__(
-        uint id,
+        int id,
         ulong sender_0,
         ulong sender_1,
         ulong sender_2,
@@ -2589,7 +2589,7 @@ SpacetimeDB.Internal.BytesSink error
 
     [UnmanagedCallersOnly(EntryPoint = "__call_procedure__")]
     public static SpacetimeDB.Internal.Errno __call_procedure__(
-        uint id,
+        int id,
         ulong sender_0,
         ulong sender_1,
         ulong sender_2,
@@ -2615,7 +2615,7 @@ SpacetimeDB.Internal.BytesSink result_sink
 
     [UnmanagedCallersOnly(EntryPoint = "__call_http_handler__")]
     public static SpacetimeDB.Internal.Errno __call_http_handler__(
-        uint id,
+        int id,
         SpacetimeDB.Timestamp timestamp,
         SpacetimeDB.Internal.BytesSource request,
         SpacetimeDB.Internal.BytesSource request_body,
@@ -2633,7 +2633,7 @@ SpacetimeDB.Internal.BytesSink response_body_sink
 
     [UnmanagedCallersOnly(EntryPoint = "__call_view__")]
     public static SpacetimeDB.Internal.Errno __call_view__(
-        uint id,
+        int id,
         ulong sender_0,
         ulong sender_1,
         ulong sender_2,
@@ -2653,7 +2653,7 @@ SpacetimeDB.Internal.BytesSink sink
 
     [UnmanagedCallersOnly(EntryPoint = "__call_view_anon__")]
     public static SpacetimeDB.Internal.Errno __call_view_anon__(
-        uint id,
+        int id,
         SpacetimeDB.Internal.BytesSource args,
         SpacetimeDB.Internal.BytesSink sink
     ) => SpacetimeDB.Internal.Module.__call_view_anon__(id, args, sink);
diff --git a/crates/bindings-csharp/Codegen/Module.cs b/crates/bindings-csharp/Codegen/Module.cs
index 34040525b94..43bbc702687 100644
--- a/crates/bindings-csharp/Codegen/Module.cs
+++ b/crates/bindings-csharp/Codegen/Module.cs
@@ -2896,7 +2896,7 @@ public static void Main() {
 
                         [UnmanagedCallersOnly(EntryPoint = "__call_reducer__")]
                         public static SpacetimeDB.Internal.Errno __call_reducer__(
-                            uint id,
+                            int id,
                             ulong sender_0,
                             ulong sender_1,
                             ulong sender_2,
@@ -2921,7 +2921,7 @@ SpacetimeDB.Internal.BytesSink error
                         
                         [UnmanagedCallersOnly(EntryPoint = "__call_procedure__")]
                         public static SpacetimeDB.Internal.Errno __call_procedure__(
-                            uint id,
+                            int id,
                             ulong sender_0,
                             ulong sender_1,
                             ulong sender_2,
@@ -2946,7 +2946,7 @@ SpacetimeDB.Internal.BytesSink result_sink
 
                         [UnmanagedCallersOnly(EntryPoint = "__call_http_handler__")]
                         public static SpacetimeDB.Internal.Errno __call_http_handler__(
-                            uint id,
+                            int id,
                             SpacetimeDB.Timestamp timestamp,
                             SpacetimeDB.Internal.BytesSource request,
                             SpacetimeDB.Internal.BytesSource request_body,
@@ -2963,7 +2963,7 @@ SpacetimeDB.Internal.BytesSink response_body_sink
                         
                         [UnmanagedCallersOnly(EntryPoint = "__call_view__")]
                         public static SpacetimeDB.Internal.Errno __call_view__(
-                            uint id,
+                            int id,
                             ulong sender_0,
                             ulong sender_1,
                             ulong sender_2,
@@ -2982,7 +2982,7 @@ SpacetimeDB.Internal.BytesSink sink
 
                         [UnmanagedCallersOnly(EntryPoint = "__call_view_anon__")]
                         public static SpacetimeDB.Internal.Errno __call_view_anon__(
-                            uint id,
+                            int id,
                             SpacetimeDB.Internal.BytesSource args,
                             SpacetimeDB.Internal.BytesSink sink
                         ) => SpacetimeDB.Internal.Module.__call_view_anon__(
diff --git a/crates/bindings-csharp/Runtime/Http.cs b/crates/bindings-csharp/Runtime/Http.cs
index 2567f4a11e5..0a6bd712de0 100644
--- a/crates/bindings-csharp/Runtime/Http.cs
+++ b/crates/bindings-csharp/Runtime/Http.cs
@@ -331,9 +331,9 @@ public Result<HttpResponse, HttpError> Send(HttpRequest request)
 
             var status = FFI.procedure_http_request(
                 requestBytes,
-                (uint)requestBytes.Length,
+                requestBytes.Length,
                 bodyBytes,
-                (uint)bodyBytes.Length,
+                bodyBytes.Length,
                 out var out_
             );
 
diff --git a/crates/bindings-csharp/Runtime/Internal/FFI.cs b/crates/bindings-csharp/Runtime/Internal/FFI.cs
index c9f07994f1d..380f10ba5f0 100644
--- a/crates/bindings-csharp/Runtime/Internal/FFI.cs
+++ b/crates/bindings-csharp/Runtime/Internal/FFI.cs
@@ -199,16 +199,16 @@ public readonly record struct RowIter(uint Handle)
     [WasmImportLinkage]
     [LibraryImport(StdbNamespace10_0)]
     public static partial CheckedStatus table_id_from_name(
-        [In] byte[] name,
-        uint name_len,
+        ReadOnlySpan<byte> name,
+        int name_len,
         out TableId out_
     );
 
     [WasmImportLinkage]
     [LibraryImport(StdbNamespace10_0)]
     public static partial CheckedStatus index_id_from_name(
-        [In] byte[] name,
-        uint name_len,
+        ReadOnlySpan<byte> name,
+        int name_len,
         out IndexId out_
     );
 
@@ -228,7 +228,7 @@ out RowIter out_
     public static partial CheckedStatus datastore_index_scan_point_bsatn(
         IndexId index_id,
         ReadOnlySpan<byte> point,
-        uint point_len,
+        int point_len,
         out RowIter out_
     );
 
@@ -237,7 +237,7 @@ out RowIter out_
     public static partial CheckedStatus datastore_delete_by_index_scan_point_bsatn(
         IndexId index_id,
         ReadOnlySpan<byte> point,
-        uint point_len,
+        int point_len,
         out uint out_
     );
 
@@ -246,12 +246,12 @@ out uint out_
     public static partial CheckedStatus datastore_index_scan_range_bsatn(
         IndexId index_id,
         ReadOnlySpan<byte> prefix,
-        uint prefix_len,
+        int prefix_len,
         ColId prefix_elems,
         ReadOnlySpan<byte> rstart,
-        uint rstart_len,
+        int rstart_len,
         ReadOnlySpan<byte> rend,
-        uint rend_len,
+        int rend_len,
         out RowIter out_
     );
 
@@ -259,8 +259,8 @@ out RowIter out_
     [LibraryImport(StdbNamespace10_0)]
     public static partial Errno row_iter_bsatn_advance(
         RowIter iter_handle,
-        [MarshalUsing(CountElementName = nameof(buffer_len))] [Out] byte[] buffer,
-        ref uint buffer_len
+        Span<byte> buffer,
+        ref int buffer_len
     );
 
     [WasmImportLinkage]
@@ -272,7 +272,7 @@ ref uint buffer_len
     public static partial CheckedStatus datastore_insert_bsatn(
         TableId table_id,
         Span<byte> row,
-        ref uint row_len
+        ref int row_len
     );
 
     [WasmImportLinkage]
@@ -281,7 +281,7 @@ public static partial CheckedStatus datastore_update_bsatn(
         TableId table_id,
         IndexId index_id,
         Span<byte> row,
-        ref uint row_len
+        ref int row_len
     );
 
     [WasmImportLinkage]
@@ -289,12 +289,12 @@ ref uint row_len
     public static partial CheckedStatus datastore_delete_by_index_scan_range_bsatn(
         IndexId index_id,
         ReadOnlySpan<byte> prefix,
-        uint prefix_len,
+        int prefix_len,
         ColId prefix_elems,
         ReadOnlySpan<byte> rstart,
-        uint rstart_len,
+        int rstart_len,
         ReadOnlySpan<byte> rend,
-        uint rend_len,
+        int rend_len,
         out uint out_
     );
 
@@ -302,8 +302,8 @@ out uint out_
     [LibraryImport(StdbNamespace10_0)]
     public static partial CheckedStatus datastore_delete_all_by_eq_bsatn(
         TableId table_id,
-        [In] byte[] relation,
-        uint relation_len,
+        ReadOnlySpan<byte> relation,
+        int relation_len,
         out uint out_
     );
 
@@ -316,7 +316,7 @@ out uint out_
     public static partial Errno bytes_source_read(
         BytesSource source,
         Span<byte> buffer,
-        ref uint buffer_len
+        ref int buffer_len
     );
 
     [WasmImportLinkage]
@@ -324,7 +324,7 @@ ref uint buffer_len
     public static partial CheckedStatus bytes_sink_write(
         BytesSink sink,
         ReadOnlySpan<byte> buffer,
-        ref uint buffer_len
+        ref int buffer_len
     );
 
     public enum LogLevel : byte
@@ -341,13 +341,13 @@ public enum LogLevel : byte
     [LibraryImport(StdbNamespace10_0)]
     public static partial void console_log(
         LogLevel level,
-        [In] byte[] target,
-        uint target_len,
-        [In] byte[] filename,
-        uint filename_len,
+        ReadOnlySpan<byte> target,
+        int target_len,
+        ReadOnlySpan<byte> filename,
+        int filename_len,
         uint line_number,
-        [In] byte[] message,
-        uint message_len
+        ReadOnlySpan<byte> message,
+        int message_len
     );
 
     [NativeMarshalling(typeof(ConsoleTimerIdMarshaller))]
@@ -377,7 +377,7 @@ internal static class ConsoleTimerIdMarshaller
 
     [WasmImportLinkage]
     [LibraryImport(StdbNamespace10_0)]
-    public static partial ConsoleTimerId console_timer_start([In] byte[] name, uint name_len);
+    public static partial ConsoleTimerId console_timer_start(ReadOnlySpan<byte> name, int name_len);
 
     [WasmImportLinkage]
     [LibraryImport(StdbNamespace10_0)]
@@ -386,10 +386,10 @@ internal static class ConsoleTimerIdMarshaller
     [WasmImportLinkage]
     [LibraryImport(StdbNamespace10_0)]
     public static partial void volatile_nonatomic_schedule_immediate(
-        [In] byte[] name,
-        uint name_len,
-        [In] byte[] args,
-        uint args_len
+        ReadOnlySpan<byte> name,
+        int name_len,
+        ReadOnlySpan<byte> args,
+        int args_len
     );
 
     // Note #1: our Identity type has the same layout as a fixed-size 32-byte little-endian buffer,
@@ -436,9 +436,9 @@ public readonly struct BytesSourcePair
     [LibraryImport(StdbNamespace10_3, EntryPoint = "procedure_http_request")]
     public static partial Errno procedure_http_request(
         ReadOnlySpan<byte> request,
-        uint request_len,
+        int request_len,
         ReadOnlySpan<byte> body,
-        uint body_len,
+        int body_len,
         out BytesSourcePair out_
     );
 }
diff --git a/crates/bindings-csharp/Runtime/Internal/IIndex.cs b/crates/bindings-csharp/Runtime/Internal/IIndex.cs
index 33525924f2d..1bfcc05cd38 100644
--- a/crates/bindings-csharp/Runtime/Internal/IIndex.cs
+++ b/crates/bindings-csharp/Runtime/Internal/IIndex.cs
@@ -14,7 +14,7 @@ public abstract class IndexBase<Row>
     public IndexBase(string name)
     {
         var name_bytes = System.Text.Encoding.UTF8.GetBytes(name);
-        FFI.index_id_from_name(name_bytes, (uint)name_bytes.Length, out indexId);
+        FFI.index_id_from_name(name_bytes, name_bytes.Length, out indexId);
     }
 
     private static void ToParams<Bounds>(
@@ -53,12 +53,12 @@ protected uint DoDelete<Bounds>(Bounds bounds)
         FFI.datastore_delete_by_index_scan_range_bsatn(
             indexId,
             prefix,
-            (uint)prefix.Length,
+            prefix.Length,
             prefixElems,
             rstart,
-            (uint)rstart.Length,
+            rstart.Length,
             rend,
-            (uint)rend.Length,
+            rend.Length,
             out var out_
         );
         return out_;
@@ -73,12 +73,12 @@ protected override void IterStart(out FFI.RowIter handle)
             FFI.datastore_index_scan_range_bsatn(
                 indexId,
                 prefix,
-                (uint)prefix.Length,
+                prefix.Length,
                 prefixElems,
                 rstart,
-                (uint)rstart.Length,
+                rstart.Length,
                 rend,
-                (uint)rend.Length,
+                rend.Length,
                 out handle
             );
         }
@@ -102,7 +102,7 @@ public abstract class UniqueIndex<Handle, Row, T, RW>(string name) : IndexBase<R
     private sealed class RawPointIter(FFI.IndexId indexId, byte[] point) : RawTableIterBase<Row>
     {
         protected override void IterStart(out FFI.RowIter handle) =>
-            FFI.datastore_index_scan_point_bsatn(indexId, point, (uint)point.Length, out handle);
+            FFI.datastore_index_scan_point_bsatn(indexId, point, point.Length, out handle);
     }
 
     protected IEnumerable<Row> DoFilter(T key) => DoFilter(ToBounds(key));
@@ -116,7 +116,7 @@ public bool Delete(T key)
         FFI.datastore_delete_by_index_scan_point_bsatn(
             indexId,
             point,
-            (uint)point.Length,
+            point.Length,
             out var numDeleted
         );
         return numDeleted > 0;
@@ -148,7 +148,7 @@ protected Row DoUpdate(Row row)
     {
         // Insert the row.
         var bytes = IStructuralReadWrite.ToBytes(row);
-        var bytes_len = (uint)bytes.Length;
+        var bytes_len = bytes.Length;
         FFI.datastore_update_bsatn(ITableView<Handle, Row>.tableId, indexId, bytes, ref bytes_len);
 
         return ITableView<Handle, Row>.IntegrateGeneratedColumns(row, bytes, bytes_len);
@@ -165,7 +165,7 @@ public abstract class RefUniqueIndex<Handle, Row, T, RW>(string name) : IndexBas
     private sealed class RawPointIter(FFI.IndexId indexId, byte[] point) : RawTableIterBase<Row>
     {
         protected override void IterStart(out FFI.RowIter handle) =>
-            FFI.datastore_index_scan_point_bsatn(indexId, point, (uint)point.Length, out handle);
+            FFI.datastore_index_scan_point_bsatn(indexId, point, point.Length, out handle);
     }
 
     protected IEnumerable<Row> DoFilter(T key) => DoFilter(ToBounds(key));
@@ -179,7 +179,7 @@ public bool Delete(T key)
         FFI.datastore_delete_by_index_scan_point_bsatn(
             indexId,
             point,
-            (uint)point.Length,
+            point.Length,
             out var numDeleted
         );
         return numDeleted > 0;
@@ -211,7 +211,7 @@ protected Row DoUpdate(Row row)
     {
         // Insert the row.
         var bytes = IStructuralReadWrite.ToBytes(row);
-        var bytes_len = (uint)bytes.Length;
+        var bytes_len = bytes.Length;
         FFI.datastore_update_bsatn(ITableView<Handle, Row>.tableId, indexId, bytes, ref bytes_len);
 
         return ITableView<Handle, Row>.IntegrateGeneratedColumns(row, bytes, bytes_len);
@@ -229,7 +229,7 @@ public abstract class ReadOnlyUniqueIndex<Handle, Row, T, RW>(string name)
     private sealed class RawPointIter(FFI.IndexId indexId, byte[] point) : RawTableIterBase<Row>
     {
         protected override void IterStart(out FFI.RowIter handle) =>
-            FFI.datastore_index_scan_point_bsatn(indexId, point, (uint)point.Length, out handle);
+            FFI.datastore_index_scan_point_bsatn(indexId, point, point.Length, out handle);
     }
 
     protected IEnumerable<Row> Filter(T key) => Filter(ToBounds(key));
@@ -268,7 +268,7 @@ public abstract class ReadOnlyRefUniqueIndex<Handle, Row, T, RW>(string name)
     private sealed class RawPointIter(FFI.IndexId indexId, byte[] point) : RawTableIterBase<Row>
     {
         protected override void IterStart(out FFI.RowIter handle) =>
-            FFI.datastore_index_scan_point_bsatn(indexId, point, (uint)point.Length, out handle);
+            FFI.datastore_index_scan_point_bsatn(indexId, point, point.Length, out handle);
     }
 
     protected IEnumerable<Row> Filter(T key) => Filter(ToBounds(key));
@@ -310,7 +310,7 @@ protected override void IterStart(out FFI.RowIter handle) =>
     protected ReadOnlyTableView(string tableName)
     {
         var nameBytes = Encoding.UTF8.GetBytes(tableName);
-        FFI.table_id_from_name(nameBytes, (uint)nameBytes.Length, out tableId);
+        FFI.table_id_from_name(nameBytes, nameBytes.Length, out tableId);
     }
 
     protected ulong DoCount()
diff --git a/crates/bindings-csharp/Runtime/Internal/IReducer.cs b/crates/bindings-csharp/Runtime/Internal/IReducer.cs
index 878c98a2a2e..d51b5a03206 100644
--- a/crates/bindings-csharp/Runtime/Internal/IReducer.cs
+++ b/crates/bindings-csharp/Runtime/Internal/IReducer.cs
@@ -32,9 +32,9 @@ public static void VolatileNonatomicScheduleImmediate(string name, MemoryStream
 
         FFI.volatile_nonatomic_schedule_immediate(
             name_bytes,
-            (uint)name_bytes.Length,
+            name_bytes.Length,
             args_bytes,
-            (uint)args_bytes.Length
+            args_bytes.Length
         );
     }
 }
diff --git a/crates/bindings-csharp/Runtime/Internal/ITable.cs b/crates/bindings-csharp/Runtime/Internal/ITable.cs
index a322216a1d3..e7acaa0b216 100644
--- a/crates/bindings-csharp/Runtime/Internal/ITable.cs
+++ b/crates/bindings-csharp/Runtime/Internal/ITable.cs
@@ -24,23 +24,22 @@ public bool MoveNext()
                 return false;
             }
 
-            uint buffer_len;
             while (true)
             {
-                var requested_len = (uint)buffer.Length;
-                buffer_len = requested_len;
-                var ret = FFI.row_iter_bsatn_advance(handle, buffer, ref buffer_len);
+                var requestedLen = buffer.Length;
+                var bufferLen = requestedLen;
+                var ret = FFI.row_iter_bsatn_advance(handle, buffer, ref bufferLen);
                 if (ret == Errno.EXHAUSTED)
                 {
                     handle = FFI.RowIter.INVALID;
-                    if (buffer_len == requested_len)
+                    if (bufferLen == requestedLen)
                     {
-                        buffer_len = 0;
+                        bufferLen = 0;
                     }
                 }
                 // On success, the only way `buffer_len == 0` is for the iterator to be exhausted.
                 // This happens when the host iterator was empty from the start.
-                System.Diagnostics.Debug.Assert(!(ret == Errno.OK && buffer_len == 0));
+                System.Diagnostics.Debug.Assert(!(ret == Errno.OK && bufferLen == 0));
                 switch (ret)
                 {
                     // Iterator advanced and may also be `EXHAUSTED`.
@@ -48,8 +47,8 @@ public bool MoveNext()
                     // In both cases, update `Current` to point at the valid range in the scratch `buffer`.
                     case Errno.EXHAUSTED
                     or Errno.OK:
-                        Current = new ArraySegment<byte>(buffer, 0, (int)buffer_len);
-                        return buffer_len != 0;
+                        Current = new ArraySegment<byte>(buffer, 0, bufferLen);
+                        return bufferLen != 0;
                     // Couldn't find the iterator, error!
                     case Errno.NO_SUCH_ITER:
                         throw new NoSuchIterException();
@@ -58,7 +57,7 @@ public bool MoveNext()
                     // The `buffer_len` will have been updated with the necessary size.
                     case Errno.BUFFER_TOO_SMALL:
                         ArrayPool<byte>.Shared.Return(buffer);
-                        buffer = ArrayPool<byte>.Shared.Rent((int)buffer_len);
+                        buffer = ArrayPool<byte>.Shared.Rent(bufferLen);
                         continue;
                     default:
                         throw new UnknownException(ret);
@@ -142,7 +141,7 @@ protected override void IterStart(out FFI.RowIter handle) =>
         new(() =>
         {
             var name_bytes = System.Text.Encoding.UTF8.GetBytes(tableName);
-            FFI.table_id_from_name(name_bytes, (uint)name_bytes.Length, out var out_);
+            FFI.table_id_from_name(name_bytes, name_bytes.Length, out var out_);
             return out_;
         });
 
@@ -172,16 +171,16 @@ protected static T DoInsert(T row)
     {
         // Insert the row.
         var bytes = IStructuralReadWrite.ToBytes(row);
-        var bytes_len = (uint)bytes.Length;
+        var bytes_len = bytes.Length;
         FFI.datastore_insert_bsatn(tableId, bytes, ref bytes_len);
 
         return IntegrateGeneratedColumns(row, bytes, bytes_len);
     }
 
     // Writes back any generated column values.
-    static T IntegrateGeneratedColumns(T row, byte[] bytes, uint gen_len)
+    static T IntegrateGeneratedColumns(T row, byte[] bytes, int gen_len)
     {
-        using var stream = new MemoryStream(bytes, 0, (int)gen_len);
+        using var stream = new MemoryStream(bytes, 0, gen_len);
         using var reader = new BinaryReader(stream);
         return View.ReadGenFields(reader, row);
     }
@@ -198,7 +197,7 @@ protected static bool DoDelete(T row)
         FFI.datastore_delete_all_by_eq_bsatn(
             tableId,
             stream.GetBuffer(),
-            (uint)stream.Length,
+            checked((int)stream.Length),
             out var out_
         );
         return out_ > 0;
diff --git a/crates/bindings-csharp/Runtime/Internal/Module.cs b/crates/bindings-csharp/Runtime/Internal/Module.cs
index eebd573cfc5..d850b930c77 100644
--- a/crates/bindings-csharp/Runtime/Internal/Module.cs
+++ b/crates/bindings-csharp/Runtime/Internal/Module.cs
@@ -458,8 +458,8 @@ public static byte[] Consume(this BytesSource source)
                 throw new UnknownException(ret);
         }
 
-        var buffer = new byte[len];
-        var written = 0U;
+        var buffer = new byte[checked((int)len)];
+        var written = 0;
         // Because we've reserved space in our buffer already, this loop should be unnecessary.
         // We expect the first call to `bytes_source_read` to always return `-1`.
         // I (pgoldman 2025-09-26) am leaving the loop here because there's no downside to it,
@@ -469,15 +469,15 @@ public static byte[] Consume(this BytesSource source)
         while (true)
         {
             // Write into the spare capacity of the buffer.
-            var spare = buffer.AsSpan((int)written);
-            var buf_len = (uint)spare.Length;
+            var spare = buffer.AsSpan(written);
+            var buf_len = spare.Length;
             ret = FFI.bytes_source_read(source, spare, ref buf_len);
             written += buf_len;
             switch (ret)
             {
                 // Host side source exhausted, we're done.
                 case Errno.EXHAUSTED:
-                    Array.Resize(ref buffer, (int)written);
+                    Array.Resize(ref buffer, written);
                     return buffer;
                 // Wrote the entire spare capacity.
                 // Need to reserve more space in the buffer.
@@ -498,15 +498,13 @@ public static byte[] Consume(this BytesSource source)
         }
     }
 
-    private static void Write(this BytesSink sink, byte[] bytes)
+    private static void Write(this BytesSink sink, ReadOnlySpan<byte> bytes)
     {
-        var start = 0U;
-        while (start != bytes.Length)
+        while (!bytes.IsEmpty)
         {
-            var written = (uint)bytes.Length;
-            var buffer = bytes.AsSpan((int)start);
-            FFI.bytes_sink_write(sink, buffer, ref written);
-            start += written;
+            var written = bytes.Length;
+            FFI.bytes_sink_write(sink, bytes, ref written);
+            bytes = bytes[written..];
         }
     }
 
@@ -529,7 +527,7 @@ public static void __describe_module__(BytesSink description)
     }
 
     public static Errno __call_reducer__(
-        uint id,
+        int id,
         ulong sender_0,
         ulong sender_1,
         ulong sender_2,
@@ -544,11 +542,9 @@ BytesSink error
         try
         {
             var senderIdentity = Identity.From(
-                MemoryMarshal.AsBytes([sender_0, sender_1, sender_2, sender_3]).ToArray()
-            );
-            var connectionId = ConnectionId.From(
-                MemoryMarshal.AsBytes([conn_id_0, conn_id_1]).ToArray()
+                MemoryMarshal.AsBytes([sender_0, sender_1, sender_2, sender_3])
             );
+            var connectionId = ConnectionId.From(MemoryMarshal.AsBytes([conn_id_0, conn_id_1]));
             var random = new Random((int)timestamp.MicrosecondsSinceUnixEpoch);
             var time = timestamp.ToStd();
 
@@ -556,7 +552,7 @@ BytesSink error
 
             using var stream = new MemoryStream(args.Consume());
             using var reader = new BinaryReader(stream);
-            reducers[(int)id].Invoke(reader, ctx);
+            reducers[id].Invoke(reader, ctx);
             if (stream.Position != stream.Length)
             {
                 throw new Exception("Unrecognised extra bytes in the reducer arguments");
@@ -573,7 +569,7 @@ BytesSink error
     }
 
     public static Errno __call_procedure__(
-        uint id,
+        int id,
         ulong sender_0,
         ulong sender_1,
         ulong sender_2,
@@ -588,11 +584,9 @@ BytesSink resultSink
         try
         {
             var sender = Identity.From(
-                MemoryMarshal.AsBytes([sender_0, sender_1, sender_2, sender_3]).ToArray()
-            );
-            var connectionId = ConnectionId.From(
-                MemoryMarshal.AsBytes([conn_id_0, conn_id_1]).ToArray()
+                MemoryMarshal.AsBytes([sender_0, sender_1, sender_2, sender_3])
             );
+            var connectionId = ConnectionId.From(MemoryMarshal.AsBytes([conn_id_0, conn_id_1]));
             var random = new Random((int)timestamp.MicrosecondsSinceUnixEpoch);
             var time = timestamp.ToStd();
 
@@ -600,7 +594,7 @@ BytesSink resultSink
 
             using var stream = new MemoryStream(args.Consume());
             using var reader = new BinaryReader(stream);
-            var bytes = procedures[(int)id].Invoke(reader, ctx);
+            var bytes = procedures[id].Invoke(reader, ctx);
             if (stream.Position != stream.Length)
             {
                 throw new Exception("Unrecognised extra bytes in the procedure arguments");
@@ -620,7 +614,7 @@ BytesSink resultSink
     }
 
     public static Errno __call_http_handler__(
-        uint id,
+        int id,
         Timestamp timestamp,
         BytesSource request,
         BytesSource requestBody,
@@ -643,7 +637,7 @@ BytesSink responseBodySink
                 throw new Exception("Unrecognised extra bytes in the HTTP handler request");
             }
 
-            var response = httpHandlers[(int)id]
+            var response = httpHandlers[id]
                 .Invoke(ctx, SpacetimeDB.HttpClient.FromWire(requestWire, requestBody.Consume()));
             var (responseWire, responseBody) = SpacetimeDB.HttpClient.ToWire(response);
             responseSink.Write(
@@ -685,7 +679,7 @@ BytesSink responseBodySink
     /// </para>
     /// </remarks>
     public static Errno __call_view__(
-        uint id,
+        int id,
         ulong sender_0,
         ulong sender_1,
         ulong sender_2,
@@ -697,12 +691,12 @@ BytesSink rows
         try
         {
             var sender = Identity.From(
-                MemoryMarshal.AsBytes([sender_0, sender_1, sender_2, sender_3]).ToArray()
+                MemoryMarshal.AsBytes([sender_0, sender_1, sender_2, sender_3])
             );
             var ctx = newViewContext!(sender);
             using var stream = new MemoryStream(args.Consume());
             using var reader = new BinaryReader(stream);
-            var bytes = viewDispatchers[(int)id].Invoke(reader, ctx);
+            var bytes = viewDispatchers[id].Invoke(reader, ctx);
             rows.Write(bytes);
             return (Errno)2;
         }
@@ -733,14 +727,14 @@ BytesSink rows
     /// The current ABI is identified by returning error code <c>2</c>.
     /// </para>
     /// </remarks>
-    public static Errno __call_view_anon__(uint id, BytesSource args, BytesSink rows)
+    public static Errno __call_view_anon__(int id, BytesSource args, BytesSink rows)
     {
         try
         {
             var ctx = newAnonymousViewContext!();
             using var stream = new MemoryStream(args.Consume());
             using var reader = new BinaryReader(stream);
-            var bytes = anonymousViewDispatchers[(int)id].Invoke(reader, ctx);
+            var bytes = anonymousViewDispatchers[id].Invoke(reader, ctx);
             rows.Write(bytes);
             return (Errno)2;
         }
diff --git a/crates/bindings-csharp/Runtime/Internal/Procedure.cs b/crates/bindings-csharp/Runtime/Internal/Procedure.cs
index 81d2be9a749..becd184d13b 100644
--- a/crates/bindings-csharp/Runtime/Internal/Procedure.cs
+++ b/crates/bindings-csharp/Runtime/Internal/Procedure.cs
@@ -63,9 +63,9 @@ public static void VolatileNonatomicScheduleImmediate(string name, MemoryStream
         {
             FFI.volatile_nonatomic_schedule_immediate(
                 name_bytes,
-                (uint)name_bytes.Length,
+                name_bytes.Length,
                 args_bytes,
-                (uint)args_bytes.Length
+                args_bytes.Length
             );
         }
         catch (Exception ex)
diff --git a/crates/bindings-csharp/Runtime/Log.cs b/crates/bindings-csharp/Runtime/Log.cs
index 55a78afde85..1526d32caf0 100644
--- a/crates/bindings-csharp/Runtime/Log.cs
+++ b/crates/bindings-csharp/Runtime/Log.cs
@@ -168,12 +168,12 @@ int lineNumber
         FFI.console_log(
             level,
             target_bytes,
-            (uint)target_bytes.Length,
+            target_bytes.Length,
             filename_bytes,
-            (uint)filename_bytes.Length,
+            filename_bytes.Length,
             (uint)lineNumber,
             text_bytes,
-            (uint)text_bytes.Length
+            text_bytes.Length
         );
     }
 }
diff --git a/crates/bindings-csharp/Runtime/LogStopwatch.cs b/crates/bindings-csharp/Runtime/LogStopwatch.cs
index 4804e1e77ad..5ce00519d98 100644
--- a/crates/bindings-csharp/Runtime/LogStopwatch.cs
+++ b/crates/bindings-csharp/Runtime/LogStopwatch.cs
@@ -11,7 +11,7 @@ public sealed class LogStopwatch : IDisposable
     public LogStopwatch(string name)
     {
         var name_bytes = Encoding.UTF8.GetBytes(name);
-        StopwatchId = FFI.console_timer_start(name_bytes, (uint)name_bytes.Length);
+        StopwatchId = FFI.console_timer_start(name_bytes, name_bytes.Length);
     }
 
     void IDisposable.Dispose()