diff --git a/zml/context.zig b/zml/context.zig
index 0255d49..94308ce 100644
--- a/zml/context.zig
+++ b/zml/context.zig
@@ -6,7 +6,7 @@ const runtimes = @import("runtimes");
 const std = @import("std");
 const stdx = @import("stdx");
 
-const platform = @import("platform.zig");
+const zml_platform = @import("platform.zig");
 const pjrt = @import("pjrtx.zig");
 
 const HostBuffer = @import("hostbuffer.zig").HostBuffer;
@@ -18,6 +18,10 @@ const Target = @import("platform.zig").Target;
 const available_targets = @import("platform.zig").available_targets;
 const log = std.log.scoped(.@"zml/context");
 
+test {
+    std.testing.refAllDecls(Context);
+}
+
 /// Every program using ZML must start with a `zml.Context.init(.{});`
 /// The ZML context contains global state to interact with the different
 /// devices available on your system.
@@ -149,7 +153,7 @@ pub const Context = struct {
         return platform_ orelse @panic("No platform found !");
     }
 
-    pub fn printAvailablePlatforms(self: Context, selected: platform.Platform) void {
+    pub fn printAvailablePlatforms(self: Context, selected: Platform) void {
         // List available targets
         log.info("Available Platforms:", .{});
         const selected_prefix = "✅";
@@ -157,7 +161,7 @@ pub const Context = struct {
         const selected_postfix = "(AUTO-SELECTED)";
         const not_selected_postfix = "";
 
-        for (platform.available_targets) |target| {
+        for (zml_platform.available_targets) |target| {
             log.info("  {s} {s} {s}", .{
                 if (target == selected.target) selected_prefix else not_selected_prefix,
                 @tagName(target),
diff --git a/zml/exe.zig b/zml/exe.zig
index 12a3fec..b34d5e9 100644
--- a/zml/exe.zig
+++ b/zml/exe.zig
@@ -241,8 +241,7 @@ pub const BaseExe = struct {
             shards.appendAssumeCapacity(dev_out[i]);
         }
 
-        const out_shape = self.inner.result_buffer_shapes[i];
-        return Buffer.fromPjrtBuffers(self.platform(), out_shape, shards.constSlice());
+        return Buffer.fromPjrtBuffers(self.platform, self.result_shapes[i], shards.constSlice());
     }
 };
 
diff --git a/zml/meta.zig b/zml/meta.zig
index 8a08792..2e62605 100644
--- a/zml/meta.zig
+++ b/zml/meta.zig
@@ -120,9 +120,11 @@ pub fn mapAlloc(comptime cb: anytype, allocator: std.mem.Allocator, ctx: FnParam
         return;
     }
 
+    if (@sizeOf(ToStruct) == 0) return;
+
     switch (type_info_to) {
         .Struct => |info| inline for (info.fields) |field| {
-            // if (field.is_comptime) continue;
+            if (field.is_comptime or @sizeOf(field.type) == 0) continue;
             const field_type_info = @typeInfo(field.type);
             // If the field is already a pointer, we recurse with it directly, otherwise, we recurse with a pointer to the field.
             switch (field_type_info) {
@@ -187,6 +189,8 @@ test mapAlloc {
         }
     };
 
+    const Empty = struct {};
+
     const AA = struct {
         field: A,
         array: [2]A,
@@ -195,6 +199,7 @@ test mapAlloc {
         // We want to allow conversion from comptime to runtime, because Zig type inference works like this.
         comptime static_val: u8 = 8,
         comptime static_slice: [2]A = .{ .{ .a = 11 }, .{ .a = 12 } },
+        field_with_empty: struct { A, Empty },
     };
     const BB = struct {
         field: B,
@@ -203,6 +208,7 @@ test mapAlloc {
         other: u8,
         static_val: u8,
         static_slice: []B,
+        field_with_empty: struct { B, Empty },
     };
 
     const aa: AA = .{
@@ -210,6 +216,7 @@ test mapAlloc {
         .array = .{ .{ .a = 5 }, .{ .a = 6 } },
         .other = 7,
         .slice = &.{ .{ .a = 9 }, .{ .a = 10 } },
+        .field_with_empty = .{ .{ .a = 9 }, .{} },
     };
     var bb: BB = undefined;
 
diff --git a/zml/testing.zig b/zml/testing.zig
index eebc2ce..e5626d2 100644
--- a/zml/testing.zig
+++ b/zml/testing.zig
@@ -201,8 +201,8 @@ pub fn testLayerOut(
     const exe = try zml.compileModel(alloc, fwd, layer, input_shapes, platform);
 
     const n_out_exp = activations.countLayers(out_name);
-    if (exe.inner.result_buffer_count != n_out_exp) {
-        log.warn("Reference models produces {d} outputs, but implementation produces {d}", .{ n_out_exp, exe.inner.result_buffer_count });
+    if (exe.inner.result_shapes.len != n_out_exp) {
+        log.warn("Reference models produces {d} outputs, but implementation produces {d}", .{ n_out_exp, exe.inner.result_shapes.len });
     }
     const mod = exe.prepare(layer_weights);
 
@@ -243,13 +243,13 @@ pub fn testLayerOut(
 
     var buf: [1024]u8 = undefined;
     var failed: bool = false;
-    for (0..mod.inner.result_buffer_count) |i| {
+    for (0..mod.inner.result_shapes.len) |i| {
         const full_name = std.fmt.bufPrint(&buf, "{s}.{d}", .{ out_name, i }) catch unreachable;
         const expected_out = activations.get(full_name) orelse {
             log.warn("Output buffer not found: {s}", .{full_name});
             continue;
         };
-        zml.testing.expectClose(expected_out, mod.getOutputBuffer(i), tolerance) catch |err| switch (err) {
+        zml.testing.expectClose(expected_out, mod.inner.getOutputBuffer(i), tolerance) catch |err| switch (err) {
             error.TestUnexpectedResult => {
                 log.err("{s}.{d} doesn't match !", .{ out_name, i });
                 failed = true;
@@ -263,6 +263,34 @@ pub fn testLayerOut(
     log.info("all good for {s} !", .{name});
 }
 
+test testLayer {
+    const platform = env();
+
+    // create a model
+    const layer: zml.nn.Linear = .{
+        .weight = zml.Tensor{ ._shape = zml.Shape.init(.{ 5, 2 }, .f32), ._id = .{ .buffer_id = 42 } },
+    };
+    const layer_weights: zml.Bufferized(zml.nn.Linear) = .{
+        .weight = try zml.Buffer.fromArray(
+            platform,
+            [5][2]f32{ .{ 0, 0 }, .{ 0, 1 }, .{ 1, 2 }, .{ -1, -1 }, .{ -1, 0 } },
+        ),
+    };
+
+    // create a buffer store containing the activations:
+    var activations = try zml.aio.BufferStore.init(std.testing.allocator, &.{});
+    defer activations.deinit();
+    {
+        const input = zml.HostBuffer.fromArray(&[2]f32{ 1, -1 });
+        try activations.buffers.put(activations.arena.allocator(), "model.layer.in.0", input);
+        const output = zml.HostBuffer.fromArray(&[5]f32{ 0, -1, -1, 0, -1 });
+        try activations.buffers.put(activations.arena.allocator(), "model.layer.out.0", output);
+    }
+
+    // test the ZML layer reproduces the "captured" activations:
+    try zml.testing.testLayer(platform, activations, "model.layer", layer, layer_weights, 1e-5);
+}
+
 pub inline fn expectEqual(expected: anytype, actual: @TypeOf(expected)) !void {
     return std.testing.expectEqual(expected, actual);
 }
diff --git a/zml/zml.zig b/zml/zml.zig
index 2f5b799..292708e 100644
--- a/zml/zml.zig
+++ b/zml/zml.zig
@@ -36,6 +36,7 @@ pub const compileFn = exe.compileFn;
 pub const compileModel = exe.compileModel;
 pub const FnExe = exe.FnExe;
 pub const ModuleExe = exe.ModuleExe;
+pub const ModuleSignature = exe.ModuleSignature;
 
 pub const ops = @import("ops.zig");
 pub const tools = struct {