diff --git a/changes/render3d-plan25-vulkan.md b/changes/render3d-plan25-vulkan.md
new file mode 100644
index 00000000..12970e72
--- /dev/null
+++ b/changes/render3d-plan25-vulkan.md
@@ -0,0 +1,9 @@
+bump: patch
+type: fix
+**Vulkan's host allocations can be counted, a pipeline built in play keeps nothing, and actors come
+from a pool made at start-up.** With `R3D_ALLOC_VK=1` render3d hands one set of
+`VkAllocationCallbacks` to every create and destroy; the runtime counts live bytes, the peak and
+bytes per allocation scope (`lvk_ac_bytes`, `lvk_ac_peak`, `lvk_ac_scope_bytes`, `Vk.alloc_bytes`)
+for the memory fence to read. MoltenVK 1.4.2 routes few of its own objects through them. A pipeline
+made the first time a variant is drawn frees its seventeen create infos. `actor_init` makes 512 actor
+records, so an actor first placed in play takes one instead of allocating.
diff --git a/examples/rendering/steady.ludic b/examples/rendering/steady.ludic
index e9951510..cd17b5c4 100644
--- a/examples/rendering/steady.ludic
+++ b/examples/rendering/steady.ludic
@@ -163,6 +163,18 @@ program Steady {
     let am = gltf_load(render3d_st, "packages/ludic.lab/plate", "plate.gltf", "plate")
     actor_rounds(render3d_st, am, 20)
     let grew_a = actor_rounds(render3d_st, am, 2000)
+    # with R3D_ALLOC_VK=1 MoltenVK's own host allocations are counted (plan 25.1c): what a frame
+    # leaves among them, read the same way
+    var vk_live: long = 0
+    var vk_grew: long = 0
+    if render3d_st.gvk_ac != null {
+      frame_rounds(render3d_st, 60)
+      let v0 = Vk.alloc_bytes()
+      frame_rounds(render3d_st, 600)
+      vk_live = Vk.alloc_bytes()
+      vk_grew = vk_live - v0
+      print(`steady: Vulkan's host allocations {vk_live} bytes live (object {Vk.alloc_scope_bytes(1)}, command {Vk.alloc_scope_bytes(0)}), a frame kept {vk_grew} over 600`)
+    }
     let grew_r = ramp_rounds(render3d_st, am)
     let grew_s = stream_rounds(render3d_st, am)
     let text = Fs.read_text("packages/ludic.lab/plate/plate.gltf")
@@ -194,6 +206,11 @@ program Steady {
       ok = false
       print("steady: FAILED - a frame drawing more than before leaves memory behind")
     }
+    # MoltenVK 1.4.2 honours the callbacks for few of its objects (it read 0 live): only growth fails
+    if render3d_st.gvk_ac != null and vk_grew > 0 {
+      ok = false
+      print("steady: FAILED - Vulkan's counted host allocations grow with the frame")
+    }
     if grew_s >= 4096 {
       ok = false
       print("steady: FAILED - streaming new ground leaves memory behind")
diff --git a/packages/ludic.render3d/actor.ludic b/packages/ludic.render3d/actor.ludic
index 40af73a1..91bd697b 100644
--- a/packages/ludic.render3d/actor.ludic
+++ b/packages/ludic.render3d/actor.ludic
@@ -41,6 +41,7 @@ property Actor {
   outline: float = 0.0,        # float bits: metres of rim drawn around it (0 = none)
   ocol:    floats           # the rim's colour (null = white)
 }
+const ACTOR_POOL: int = 512
 # a program and its uniform locations
 property AcProg {
   prog:     int = 0,
@@ -75,6 +76,16 @@ function ac_prog_new(render3d_st: mut Render3dState, vs: string, fs: string, def
   return a
 }
 function actor_init(render3d_st: mut Render3dState) -> void {
+  # the records play takes, made now: an actor first placed in play (a fish, a sign, a bed) made its
+  # record, matrix and tint then (actor_release gives them back to this pool)
+  if render3d_st.ac_spare == null { render3d_st.ac_spare = new []Actor }
+  let sp = render3d_st.ac_spare
+  for i in 0 .. ACTOR_POOL {
+    let a = new Actor
+    a.tint = v3_new(1.0, 1.0, 1.0)
+    a.mat = m4_new()
+    push(sp, a)
+  }
   render3d_st.ac_lit = ac_prog_new(render3d_st, "skin.vert", "model.frag", "")
   render3d_st.ac_lit_cut = ac_prog_new(render3d_st, "skin.vert", "model.frag", "#define ALPHA_TEST\n")
   render3d_st.ac_sh = ac_prog_new(render3d_st, "skin.vert", "shadow.frag", "#define SHADOW_PASS\n")
diff --git a/packages/ludic.render3d/env.ludic b/packages/ludic.render3d/env.ludic
index 446217d9..1c06c86b 100644
--- a/packages/ludic.render3d/env.ludic
+++ b/packages/ludic.render3d/env.ludic
@@ -691,6 +691,8 @@ export state Render3dState {
   stream_walks: int = 0          # streams that walked their whole ring this frame
   stream_debug_n: int = 0
   stream_scratch: floats = null
+  gvk_pipe_bufs: words = null      # a pipeline's vertex buffers, while it is made
+  gvk_ac: pointer = null           # the VkAllocationCallbacks every create and destroy is given (R3D_ALLOC_VK=1)
   gvk_prime_b: words = null        # buffers made since the frame began, read once so MoltenVK makes their
   gvk_prime_h: []long = null       # Metal buffers now (gvk_prime), and their handles
   gvk_prime_n: int = 0
diff --git a/packages/ludic.render3d/gpu_vk.ludic b/packages/ludic.render3d/gpu_vk.ludic
index 70f53a5e..f6b19194 100644
--- a/packages/ludic.render3d/gpu_vk.ludic
+++ b/packages/ludic.render3d/gpu_vk.ludic
@@ -60,6 +60,9 @@ function gvk_no_command_pooling() -> void {
 function gvk_init(render3d_st: mut Render3dState) -> bool {
   if render3d_st.gvk_ready { return true }
   gvk_no_command_pooling()
+  # MoltenVK's host allocations counted for the memory fence (plan 25.1c); every create and destroy
+  # is given the same callbacks, as Vulkan asks, so it is decided once, before the instance
+  if r3d_env_has(render3d_st, "R3D_ALLOC_VK") { render3d_st.gvk_ac = Vk.alloc_callbacks() }
   gsl_boot(render3d_st)
   if Vk.open() == 0 { render3d_st.gvk_why = "no Vulkan loader";  return false }
   gsl_init(render3d_st)
@@ -106,7 +109,7 @@ function gvk_init(render3d_st: mut Render3dState) -> bool {
     Vk.put_ptr(ici, VkInstanceCreateInfo_ppEnabledExtensionNames, iext_names)
   }
   let out = bytes(8)
-  var r = Vk.create_instance(ici, null, out)
+  var r = Vk.create_instance(ici, render3d_st.gvk_ac, out)
   if r != VK_SUCCESS { return gvk_fail(render3d_st, "vkCreateInstance", r) }
   render3d_st.gvk_inst = Vk.get_ptr(out, 0)
 
@@ -261,7 +264,7 @@ function gvk_init(render3d_st: mut Render3dState) -> bool {
     Vk.put_i32(dci, VkDeviceCreateInfo_enabledExtensionCount, n_dext)
     Vk.put_ptr(dci, VkDeviceCreateInfo_ppEnabledExtensionNames, dext_names)
   }
-  r = Vk.create_device(render3d_st.gvk_pd, dci, null, out)
+  r = Vk.create_device(render3d_st.gvk_pd, dci, render3d_st.gvk_ac, out)
   if r != VK_SUCCESS { return gvk_fail(render3d_st, "vkCreateDevice", r) }
   render3d_st.gvk_dev = Vk.get_ptr(out, 0)
   Vk.get_device_queue(render3d_st.gvk_dev, render3d_st.gvk_family, 0, out)
@@ -313,7 +316,7 @@ function gvk_alloc(render3d_st: mut Render3dState, req: bytes, want: int) -> lon
   Vk.put_i32(mai, VkMemoryAllocateInfo_memoryTypeIndex, t)
   let out = gvk_tmp(render3d_st, 8)
   render3d_st.gvk_mk_mem += 1
-  let r = Vk.allocate_memory(render3d_st.gvk_dev, mai, null, out)
+  let r = Vk.allocate_memory(render3d_st.gvk_dev, mai, render3d_st.gvk_ac, out)
   if r != VK_SUCCESS { print(`r3d: vulkan: vkAllocateMemory failed (VkResult {r})`);  return zero }
   render3d_st.gvk_n_allocs += 1
   return gvk_handle(out)
@@ -354,7 +357,7 @@ function gvk_mem_raw(render3d_st: mut Render3dState, t: int, size: int, host: bo
   Vk.put_i32(mai, VkMemoryAllocateInfo_memoryTypeIndex, t)
   let out = gvk_tmp(render3d_st, 8)
   render3d_st.gvk_mk_mem += 1
-  let r = Vk.allocate_memory(render3d_st.gvk_dev, mai, null, out)
+  let r = Vk.allocate_memory(render3d_st.gvk_dev, mai, render3d_st.gvk_ac, out)
   if r != VK_SUCCESS { gvk_note(render3d_st, `r3d: vulkan: vkAllocateMemory of {size} bytes failed (VkResult {r}, {render3d_st.gvk_n_allocs} allocations live)`);  return zero }
   render3d_st.gvk_n_allocs += 1
   let mem = gvk_handle(out)
@@ -473,7 +476,7 @@ function gvk_mem_free(render3d_st: mut Render3dState, a: int) -> void {
   if b < 0 {
     if render3d_st.gvk_al_map[a] != null { Vk.unmap_memory(render3d_st.gvk_dev, render3d_st.gvk_al_mem[a]) }
     render3d_st.gvk_mk_x_mem += 1
-    Vk.free_memory(render3d_st.gvk_dev, render3d_st.gvk_al_mem[a], null)
+    Vk.free_memory(render3d_st.gvk_dev, render3d_st.gvk_al_mem[a], render3d_st.gvk_ac)
     render3d_st.gvk_n_allocs -= 1
   } else {
     var off = render3d_st.gvk_al_off[a]
@@ -493,7 +496,7 @@ function gvk_mem_free(render3d_st: mut Render3dState, a: int) -> void {
       # the block is empty again: give it back, or a world swapped out keeps its memory for good
       if render3d_st.gvk_blk_map[b] != null { Vk.unmap_memory(render3d_st.gvk_dev, render3d_st.gvk_blk_mem[b]) }
       render3d_st.gvk_mk_x_mem += 1
-      Vk.free_memory(render3d_st.gvk_dev, render3d_st.gvk_blk_mem[b], null)
+      Vk.free_memory(render3d_st.gvk_dev, render3d_st.gvk_blk_mem[b], render3d_st.gvk_ac)
       render3d_st.gvk_n_allocs -= 1
       render3d_st.gvk_blk_mem[b] = zero;  render3d_st.gvk_blk_map[b] = null;  render3d_st.gvk_blk_kind[b] = -1;  render3d_st.gvk_blk_size[b] = 0
     } else {
@@ -515,17 +518,17 @@ function gvk_cmd_init(render3d_st: mut Render3dState) -> bool {
   Vk.put_i32(cpi, VkCommandPoolCreateInfo_flags, VK_COMMAND_POOL_CREATE_RESET_COMMAND_BUFFER_BIT)
   Vk.put_i32(cpi, VkCommandPoolCreateInfo_queueFamilyIndex, render3d_st.gvk_family)
   let out = bytes(8)
-  var r = Vk.create_command_pool(render3d_st.gvk_dev, cpi, null, out)
+  var r = Vk.create_command_pool(render3d_st.gvk_dev, cpi, render3d_st.gvk_ac, out)
   if r != VK_SUCCESS { return gvk_fail(render3d_st, "vkCreateCommandPool", r) }
   render3d_st.gvk_pool = gvk_handle(out)
   let fci = bytes(VkFenceCreateInfo_sizeof)
   Vk.zero(fci, VkFenceCreateInfo_sizeof)
   Vk.put_i32(fci, VkFenceCreateInfo_sType, VK_STRUCTURE_TYPE_FENCE_CREATE_INFO)
   render3d_st.gvk_fence = bytes(8)
-  r = Vk.create_fence(render3d_st.gvk_dev, fci, null, render3d_st.gvk_fence)
+  r = Vk.create_fence(render3d_st.gvk_dev, fci, render3d_st.gvk_ac, render3d_st.gvk_fence)
   if r != VK_SUCCESS { return gvk_fail(render3d_st, "vkCreateFence", r) }
   render3d_st.gvk_frame_fence = bytes(8)
-  r = Vk.create_fence(render3d_st.gvk_dev, fci, null, render3d_st.gvk_frame_fence)
+  r = Vk.create_fence(render3d_st.gvk_dev, fci, render3d_st.gvk_ac, render3d_st.gvk_frame_fence)
   if r != VK_SUCCESS { return gvk_fail(render3d_st, "vkCreateFence", r) }
   return true
 }
@@ -645,12 +648,12 @@ function gvk_shutdown(render3d_st: mut Render3dState) -> void {
   gvk_frame_wait(render3d_st)
   Vk.device_wait_idle(render3d_st.gvk_dev)
   gsl_shutdown(render3d_st)
-  Vk.destroy_fence(render3d_st.gvk_dev, Vk.get_i64(render3d_st.gvk_fence, 0), null)
-  Vk.destroy_fence(render3d_st.gvk_dev, Vk.get_i64(render3d_st.gvk_frame_fence, 0), null)
-  Vk.destroy_command_pool(render3d_st.gvk_dev, render3d_st.gvk_pool, null)
-  if render3d_st.gvk_prime_dst != 0 { Vk.destroy_buffer(render3d_st.gvk_dev, render3d_st.gvk_prime_dst, null);  render3d_st.gvk_prime_dst = 0 }
-  Vk.destroy_device(render3d_st.gvk_dev, null)
-  Vk.destroy_instance(render3d_st.gvk_inst, null)
+  Vk.destroy_fence(render3d_st.gvk_dev, Vk.get_i64(render3d_st.gvk_fence, 0), render3d_st.gvk_ac)
+  Vk.destroy_fence(render3d_st.gvk_dev, Vk.get_i64(render3d_st.gvk_frame_fence, 0), render3d_st.gvk_ac)
+  Vk.destroy_command_pool(render3d_st.gvk_dev, render3d_st.gvk_pool, render3d_st.gvk_ac)
+  if render3d_st.gvk_prime_dst != 0 { Vk.destroy_buffer(render3d_st.gvk_dev, render3d_st.gvk_prime_dst, render3d_st.gvk_ac);  render3d_st.gvk_prime_dst = 0 }
+  Vk.destroy_device(render3d_st.gvk_dev, render3d_st.gvk_ac)
+  Vk.destroy_instance(render3d_st.gvk_inst, render3d_st.gvk_ac)
   render3d_st.gvk_ready = false
 }
 
@@ -668,7 +671,7 @@ function gvk_query_new(render3d_st: mut Render3dState, n: int, ids: words) -> vo
   Vk.put_i32(qci, VkQueryPoolCreateInfo_queryType, VK_QUERY_TYPE_TIMESTAMP)
   Vk.put_i32(qci, VkQueryPoolCreateInfo_queryCount, n * 2)
   let out = gvk_tmp(render3d_st, 8)
-  if Vk.create_query_pool(render3d_st.gvk_dev, qci, null, out) != VK_SUCCESS { return }
+  if Vk.create_query_pool(render3d_st.gvk_dev, qci, render3d_st.gvk_ac, out) != VK_SUCCESS { return }
   render3d_st.gvk_qpool = gvk_handle(out)
   Vk.reset_query_pool(render3d_st.gvk_dev, render3d_st.gvk_qpool, 0, n * 2)
 }
diff --git a/packages/ludic.render3d/gpu_vk_draw.ludic b/packages/ludic.render3d/gpu_vk_draw.ludic
index b56bd38d..d4045aa3 100644
--- a/packages/ludic.render3d/gpu_vk_draw.ludic
+++ b/packages/ludic.render3d/gpu_vk_draw.ludic
@@ -36,7 +36,7 @@ function gvk_module(render3d_st: mut Render3dState, path: string) -> long {
   Vk.put_i64(smci, VkShaderModuleCreateInfo_codeSize, code_size)
   Vk.put_ptr(smci, VkShaderModuleCreateInfo_pCode, spv)
   let out = bytes(8)
-  let r = Vk.create_shader_module(render3d_st.gvk_dev, smci, null, out)
+  let r = Vk.create_shader_module(render3d_st.gvk_dev, smci, render3d_st.gvk_ac, out)
   if r != VK_SUCCESS { gvk_fail(render3d_st, `vkCreateShaderModule {path}`, r);  return zero }
   return gvk_handle(out)
 }
@@ -103,7 +103,7 @@ function gvk_program(render3d_st: mut Render3dState, p: int, key: string, spv_di
   Vk.put_i32(dslci, VkDescriptorSetLayoutCreateInfo_bindingCount, nb)
   Vk.put_ptr(dslci, VkDescriptorSetLayoutCreateInfo_pBindings, binds)
   let dsl = bytes(8)
-  var r = Vk.create_descriptor_set_layout(render3d_st.gvk_dev, dslci, null, dsl)
+  var r = Vk.create_descriptor_set_layout(render3d_st.gvk_dev, dslci, render3d_st.gvk_ac, dsl)
   if r != VK_SUCCESS { return gvk_fail(render3d_st, `vkCreateDescriptorSetLayout for {key}`, r) }
   let plci = bytes(VkPipelineLayoutCreateInfo_sizeof)
   Vk.zero(plci, VkPipelineLayoutCreateInfo_sizeof)
@@ -111,7 +111,7 @@ function gvk_program(render3d_st: mut Render3dState, p: int, key: string, spv_di
   Vk.put_i32(plci, VkPipelineLayoutCreateInfo_setLayoutCount, 1)
   Vk.put_ptr(plci, VkPipelineLayoutCreateInfo_pSetLayouts, dsl)
   let out = bytes(8)
-  r = Vk.create_pipeline_layout(render3d_st.gvk_dev, plci, null, out)
+  r = Vk.create_pipeline_layout(render3d_st.gvk_dev, plci, render3d_st.gvk_ac, out)
   if r != VK_SUCCESS { return gvk_fail(render3d_st, `vkCreatePipelineLayout for {key}`, r) }
   render3d_st.gvk_prog_var[p] = v;  render3d_st.gvk_prog_vs[p] = vs;  render3d_st.gvk_prog_fs[p] = fs
   render3d_st.gvk_prog_dsl[p] = Vk.get_i64(dsl, 0);  render3d_st.gvk_prog_layout[p] = gvk_handle(out)
@@ -153,7 +153,7 @@ function gvk_compute_new_tex(render3d_st: mut Render3dState, name: string, n_buf
   Vk.put_i32(dslci, VkDescriptorSetLayoutCreateInfo_bindingCount, nb)
   Vk.put_ptr(dslci, VkDescriptorSetLayoutCreateInfo_pBindings, binds)
   let dsl = bytes(8)
-  var r = Vk.create_descriptor_set_layout(render3d_st.gvk_dev, dslci, null, dsl)
+  var r = Vk.create_descriptor_set_layout(render3d_st.gvk_dev, dslci, render3d_st.gvk_ac, dsl)
   if r != VK_SUCCESS { gvk_fail(render3d_st, `vkCreateDescriptorSetLayout for compute {name}`, r);  return 0 }
   let plci = bytes(VkPipelineLayoutCreateInfo_sizeof)
   Vk.zero(plci, VkPipelineLayoutCreateInfo_sizeof)
@@ -161,7 +161,7 @@ function gvk_compute_new_tex(render3d_st: mut Render3dState, name: string, n_buf
   Vk.put_i32(plci, VkPipelineLayoutCreateInfo_setLayoutCount, 1)
   Vk.put_ptr(plci, VkPipelineLayoutCreateInfo_pSetLayouts, dsl)
   let out = bytes(8)
-  r = Vk.create_pipeline_layout(render3d_st.gvk_dev, plci, null, out)
+  r = Vk.create_pipeline_layout(render3d_st.gvk_dev, plci, render3d_st.gvk_ac, out)
   if r != VK_SUCCESS { gvk_fail(render3d_st, `vkCreatePipelineLayout for compute {name}`, r);  return 0 }
   let layout = gvk_handle(out)
   let cpci = bytes(VkComputePipelineCreateInfo_sizeof)
@@ -173,7 +173,7 @@ function gvk_compute_new_tex(render3d_st: mut Render3dState, name: string, n_buf
   Vk.put_i64(cpci, so + VkPipelineShaderStageCreateInfo_module, module)
   Vk.put_ptr(cpci, so + VkPipelineShaderStageCreateInfo_pName, "main")
   Vk.put_i64(cpci, VkComputePipelineCreateInfo_layout, layout)
-  r = Vk.create_compute_pipelines(render3d_st.gvk_dev, zero, 1, cpci, null, out)
+  r = Vk.create_compute_pipelines(render3d_st.gvk_dev, zero, 1, cpci, render3d_st.gvk_ac, out)
   if r != VK_SUCCESS { gvk_fail(render3d_st, `vkCreateComputePipelines {name}`, r);  return 0 }
   push(render3d_st.gvk_cp_pipe, gvk_handle(out));  push(render3d_st.gvk_cp_layout, layout);  push(render3d_st.gvk_cp_dsl, Vk.get_i64(dsl, 0));  push(render3d_st.gvk_cp_nbuf, n_bufs)
   push(render3d_st.gvk_cp_ntex, n_tex)
@@ -393,7 +393,7 @@ function gvk_pipeline(render3d_st: mut Render3dState, p: int, m: Mesh, st: GvkSt
   let v = render3d_st.gvk_prog_var[p]
   if v == null { return zero }
   let key = `{p}|{gvk_layout_key(m)}|{st.depth_test},{st.depth_write},{st.depth_func},{st.blend},{st.blend_src},{st.blend_dst},{st.cull},{st.cull_face},{st.color_write},{st.a2c},{st.bias},{st.bias_factor},{st.bias_units},{st.wireframe}|{n_color},{color_fmt},{depth_fmt},{samples}`
-  if render3d_st.gvk_pipe_keys == null { render3d_st.gvk_pipe_keys = new []string;  render3d_st.gvk_pipe = new []long }
+  if render3d_st.gvk_pipe_keys == null { render3d_st.gvk_pipe_keys = new []string;  render3d_st.gvk_pipe = new []long;  render3d_st.gvk_pipe_bufs = words(GPU_MAX_VBUFS) }
   for i in 0 .. len(render3d_st.gvk_pipe_keys) { if render3d_st.gvk_pipe_keys[i] == key { return render3d_st.gvk_pipe[i] } }
 
   let ss = VkPipelineShaderStageCreateInfo_sizeof
@@ -419,7 +419,7 @@ function gvk_pipeline(render3d_st: mut Render3dState, p: int, m: Mesh, st: GvkSt
   var na = 0
   var nbd = 0
   if m != null and m.attrs != null {
-    let bufs = words(GPU_MAX_VBUFS)
+    let bufs = render3d_st.gvk_pipe_bufs
     for i in 0 .. m.n_attrs {
       let o = i * GPU_ATTR_W
       if m.attrs[o + 1] == 0 { continue }
@@ -566,9 +566,12 @@ function gvk_pipeline(render3d_st: mut Render3dState, p: int, m: Mesh, st: GvkSt
   Vk.put_ptr(gpci, VkGraphicsPipelineCreateInfo_pDynamicState, dys)
   Vk.put_i64(gpci, VkGraphicsPipelineCreateInfo_layout, render3d_st.gvk_prog_layout[p])
   let out = bytes(8)
-  let r = Vk.create_graphics_pipelines(render3d_st.gvk_dev, zero, 1, gpci, null, out)
-  if r != VK_SUCCESS { gvk_fail(render3d_st, `vkCreateGraphicsPipelines for {v.vs} + {v.fs}`, r);  return zero }
+  let r = Vk.create_graphics_pipelines(render3d_st.gvk_dev, zero, 1, gpci, render3d_st.gvk_ac, out)
   let pipe = gvk_handle(out)
+  # the create infos are read by the create and go with it: a pipeline first met in play kept all of them
+  free(stages);  free(attrs);  free(bnds);  free(vin);  free(ias);  free(vps);  free(rs);  free(ms);  free(ds)
+  free(cba);  free(cbs);  free(dyn_states);  free(dys);  free(formats);  free(prci);  free(gpci);  free(out)
+  if r != VK_SUCCESS { gvk_fail(render3d_st, `vkCreateGraphicsPipelines for {v.vs} + {v.fs}`, r);  return zero }
   # R3D_VK_PROF names each pipeline as it is made: one made during play is a stall a warm-up missed
   if gvk_prof(render3d_st) { render3d_st.gvk_n_pipe_new += 1;  print(`r3d: vulkan pipeline {len(render3d_st.gvk_pipe) + 1}: {v.vs} + {v.fs}, {n_color} colour format {color_fmt}, depth {depth_fmt}, {samples}x`) }
   push(render3d_st.gvk_pipe_keys, key)
@@ -706,7 +709,7 @@ function gvk_frame_init(render3d_st: mut Render3dState) -> bool {
   render3d_st.gvk_dpools = new []long
   for k in 0 .. 2 {
     render3d_st.gvk_mk_dpool += 1
-    let r = Vk.create_descriptor_pool(render3d_st.gvk_dev, dpci, null, out)
+    let r = Vk.create_descriptor_pool(render3d_st.gvk_dev, dpci, render3d_st.gvk_ac, out)
     if r != VK_SUCCESS { return gvk_fail(render3d_st, "vkCreateDescriptorPool", r) }
     push(render3d_st.gvk_dpools, gvk_handle(out))
   }
@@ -761,7 +764,7 @@ function gvk_kpool_make(render3d_st: mut Render3dState) -> bool {
   Vk.put_ptr(dpci, VkDescriptorPoolCreateInfo_pPoolSizes, sizes)
   let out = bytes(8)
   render3d_st.gvk_mk_dpool += 1
-  let r = Vk.create_descriptor_pool(render3d_st.gvk_dev, dpci, null, out)
+  let r = Vk.create_descriptor_pool(render3d_st.gvk_dev, dpci, render3d_st.gvk_ac, out)
   if r != VK_SUCCESS { return gvk_fail(render3d_st, "vkCreateDescriptorPool (kept sets)", r) }
   render3d_st.gvk_kpool = gvk_handle(out)
   gvk_sc_clear(render3d_st)
@@ -1042,7 +1045,7 @@ function gvk_view_of(render3d_st: mut Render3dState, tex: int, layer1: int) -> l
   let out = bytes(8)
   let zero: long = 0
   render3d_st.gvk_mk_view += 1
-  if Vk.create_image_view(render3d_st.gvk_dev, vci, null, out) != VK_SUCCESS { return zero }
+  if Vk.create_image_view(render3d_st.gvk_dev, vci, render3d_st.gvk_ac, out) != VK_SUCCESS { return zero }
   push(render3d_st.gvk_layer_views, key)
   push(render3d_st.gvk_layer_view, gvk_handle(out))
   push(render3d_st.gvk_layer_view_tex, tex)
@@ -1636,7 +1639,7 @@ function gvk_surface_os(render3d_st: mut Render3dState, out: pointer) -> bool {
     Vk.zero(mci, VkMetalSurfaceCreateInfoEXT_sizeof)
     Vk.put_i32(mci, VkMetalSurfaceCreateInfoEXT_sType, VK_STRUCTURE_TYPE_METAL_SURFACE_CREATE_INFO_EXT)
     Vk.put_ptr(mci, VkMetalSurfaceCreateInfoEXT_pLayer, layer)
-    let rm = Vk.create_metal_surface_ext(render3d_st.gvk_inst, mci, null, out)
+    let rm = Vk.create_metal_surface_ext(render3d_st.gvk_inst, mci, render3d_st.gvk_ac, out)
     if rm != VK_SUCCESS { return gvk_fail(render3d_st, "vkCreateMetalSurfaceEXT", rm) }
     return true
   }
@@ -1647,7 +1650,7 @@ function gvk_surface_os(render3d_st: mut Render3dState, out: pointer) -> bool {
   Vk.put_i32(sci, VkWin32SurfaceCreateInfoKHR_sType, VK_STRUCTURE_TYPE_WIN32_SURFACE_CREATE_INFO_KHR)
   Vk.put_ptr(sci, VkWin32SurfaceCreateInfoKHR_hinstance, win_native_instance())
   Vk.put_ptr(sci, VkWin32SurfaceCreateInfoKHR_hwnd, hwnd)
-  let r = Vk.create_win32_surface_khr(render3d_st.gvk_inst, sci, null, out)
+  let r = Vk.create_win32_surface_khr(render3d_st.gvk_inst, sci, render3d_st.gvk_ac, out)
   if r != VK_SUCCESS { return gvk_fail(render3d_st, "vkCreateWin32SurfaceKHR", r) }
   return true
 }
@@ -1665,7 +1668,7 @@ function gvk_surface_make(render3d_st: mut Render3dState) -> bool {
   Vk.zero(fci, VkFenceCreateInfo_sizeof)
   Vk.put_i32(fci, VkFenceCreateInfo_sType, VK_STRUCTURE_TYPE_FENCE_CREATE_INFO)
   render3d_st.gvk_acq_fence = bytes(8)
-  return Vk.create_fence(render3d_st.gvk_dev, fci, null, render3d_st.gvk_acq_fence) == VK_SUCCESS
+  return Vk.create_fence(render3d_st.gvk_dev, fci, render3d_st.gvk_ac, render3d_st.gvk_acq_fence) == VK_SUCCESS
 }
 
 # (Re)make the swapchain for a w x h client area. The old one is handed over and then destroyed.
@@ -1736,9 +1739,9 @@ function gvk_swap_make(render3d_st: mut Render3dState, w: int, h: int) -> bool {
   Vk.put_i32(sci, VkSwapchainCreateInfoKHR_clipped, 1)
   Vk.put_i64(sci, VkSwapchainCreateInfoKHR_oldSwapchain, render3d_st.gvk_swap)
   let out = bytes(8)
-  let r = Vk.create_swapchain_khr(render3d_st.gvk_dev, sci, null, out)
+  let r = Vk.create_swapchain_khr(render3d_st.gvk_dev, sci, render3d_st.gvk_ac, out)
   if r != VK_SUCCESS { return gvk_fail(render3d_st, "vkCreateSwapchainKHR", r) }
-  if render3d_st.gvk_swap != 0 { Vk.destroy_swapchain_khr(render3d_st.gvk_dev, render3d_st.gvk_swap, null) }
+  if render3d_st.gvk_swap != 0 { Vk.destroy_swapchain_khr(render3d_st.gvk_dev, render3d_st.gvk_swap, render3d_st.gvk_ac) }
   render3d_st.gvk_swap = gvk_handle(out)
   if render3d_st.gvk_hdr_on and render3d_st.gvk_has_hdr_meta { gvk_hdr_metadata(render3d_st) }
   Vk.put_i32(cnt, 0, 0)
diff --git a/packages/ludic.render3d/gpu_vk_res.ludic b/packages/ludic.render3d/gpu_vk_res.ludic
index 7eab6624..317b43b3 100644
--- a/packages/ludic.render3d/gpu_vk_res.ludic
+++ b/packages/ludic.render3d/gpu_vk_res.ludic
@@ -154,7 +154,7 @@ function gvk_staging(render3d_st: mut Render3dState, n: int, usage: int) -> poin
   Vk.put_i32(bci, VkBufferCreateInfo_sharingMode, VK_SHARING_MODE_EXCLUSIVE)
   let out = gvk_tmp(render3d_st, 8)
   render3d_st.gvk_mk_buf += 1
-  if Vk.create_buffer(render3d_st.gvk_dev, bci, null, out) != VK_SUCCESS { return null }
+  if Vk.create_buffer(render3d_st.gvk_dev, bci, render3d_st.gvk_ac, out) != VK_SUCCESS { return null }
   render3d_st.gvk_st_buf = gvk_handle(out)
   let req = gvk_tmp(render3d_st, VkMemoryRequirements_sizeof)
   Vk.get_buffer_memory_requirements(render3d_st.gvk_dev, render3d_st.gvk_st_buf, req)
@@ -169,9 +169,9 @@ function gvk_staging_free(render3d_st: mut Render3dState) -> void {
   gvk_frame_wait(render3d_st)                # the frame in flight may still read it
   Vk.unmap_memory(render3d_st.gvk_dev, render3d_st.gvk_st_mem)
   render3d_st.gvk_mk_x_buf += 1
-  Vk.destroy_buffer(render3d_st.gvk_dev, render3d_st.gvk_st_buf, null)
+  Vk.destroy_buffer(render3d_st.gvk_dev, render3d_st.gvk_st_buf, render3d_st.gvk_ac)
   render3d_st.gvk_mk_x_mem += 1
-  Vk.free_memory(render3d_st.gvk_dev, render3d_st.gvk_st_mem, null)
+  Vk.free_memory(render3d_st.gvk_dev, render3d_st.gvk_st_mem, render3d_st.gvk_ac)
   render3d_st.gvk_n_allocs -= 1
 }
 
@@ -211,7 +211,7 @@ function gvk_tex_storage(render3d_st: mut Render3dState, tex: int, array: bool,
   Vk.put_i32(ici, VkImageCreateInfo_initialLayout, VK_IMAGE_LAYOUT_UNDEFINED)
   let out = bytes(8)
   render3d_st.gvk_mk_img += 1
-  var r = Vk.create_image(render3d_st.gvk_dev, ici, null, out)
+  var r = Vk.create_image(render3d_st.gvk_dev, ici, render3d_st.gvk_ac, out)
   # the create infos are read by the call they are handed to and go straight after (a texture
   # made in play once left four of them behind)
   free(ici)
@@ -230,7 +230,7 @@ function gvk_tex_storage(render3d_st: mut Render3dState, tex: int, array: bool,
   # the card is full): say so instead of binding a null allocation, which the driver may accept
   if mem == 0 {
     render3d_st.gvk_mk_x_img += 1
-    Vk.destroy_image(render3d_st.gvk_dev, image, null)
+    Vk.destroy_image(render3d_st.gvk_dev, image, render3d_st.gvk_ac)
     free(out)
     return gvk_fail(render3d_st, `no device memory for a {w}x{h}x{layers} image ({render3d_st.gvk_n_allocs} allocations live)`, VK_ERROR_OUT_OF_DEVICE_MEMORY)
   }
@@ -250,7 +250,7 @@ function gvk_tex_storage(render3d_st: mut Render3dState, tex: int, array: bool,
   Vk.put_i32(vci, sr + VkImageSubresourceRange_levelCount, levels)
   Vk.put_i32(vci, sr + VkImageSubresourceRange_layerCount, layers)
   render3d_st.gvk_mk_view += 1
-  r = Vk.create_image_view(render3d_st.gvk_dev, vci, null, out)
+  r = Vk.create_image_view(render3d_st.gvk_dev, vci, render3d_st.gvk_ac, out)
   free(vci)
   let view = gvk_handle(out)
   free(out)
@@ -382,9 +382,9 @@ function gvk_tex_grow_mips(render3d_st: mut Render3dState, tex: int, w: int, h:
   gvk_barrier(render3d_st, cb, render3d_st.gvk_tex_image[tex], false, 0, 1, layers, VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL, VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL)
   let ok = gvk_once_end(render3d_st, cb)
   render3d_st.gvk_mk_x_view += 1
-  Vk.destroy_image_view(render3d_st.gvk_dev, old_view, null)
+  Vk.destroy_image_view(render3d_st.gvk_dev, old_view, render3d_st.gvk_ac)
   render3d_st.gvk_mk_x_img += 1
-  Vk.destroy_image(render3d_st.gvk_dev, old_image, null)
+  Vk.destroy_image(render3d_st.gvk_dev, old_image, render3d_st.gvk_ac)
   gvk_mem_free(render3d_st, gvk_mem_id(old_mem))
   return ok
 }
@@ -483,9 +483,9 @@ function gvk_tex_release(render3d_st: mut Render3dState, tex: int) -> void {
   if render3d_st.gvk_tex_image[tex] == 0 { return }
   let zero: long = 0
   render3d_st.gvk_mk_x_view += 1
-  Vk.destroy_image_view(render3d_st.gvk_dev, render3d_st.gvk_tex_view[tex], null)
+  Vk.destroy_image_view(render3d_st.gvk_dev, render3d_st.gvk_tex_view[tex], render3d_st.gvk_ac)
   render3d_st.gvk_mk_x_img += 1
-  Vk.destroy_image(render3d_st.gvk_dev, render3d_st.gvk_tex_image[tex], null)
+  Vk.destroy_image(render3d_st.gvk_dev, render3d_st.gvk_tex_image[tex], render3d_st.gvk_ac)
   gvk_mem_free(render3d_st, gvk_mem_id(render3d_st.gvk_tex_mem[tex]))
   gvk_layer_views_drop(render3d_st, tex)
   render3d_st.gvk_tex_image[tex] = zero;  render3d_st.gvk_tex_view[tex] = zero;  render3d_st.gvk_tex_mem[tex] = zero
@@ -504,7 +504,7 @@ function gvk_layer_views_drop(render3d_st: mut Render3dState, tex: int) -> void
   for i in 0 .. len(keys) {
     if texs[i] == tex {
       render3d_st.gvk_mk_x_view += 1
-      Vk.destroy_image_view(render3d_st.gvk_dev, views[i], null)
+      Vk.destroy_image_view(render3d_st.gvk_dev, views[i], render3d_st.gvk_ac)
     } else {
       keys[w] = keys[i];  views[w] = views[i];  texs[w] = texs[i]
       w += 1
@@ -615,7 +615,7 @@ function gvk_sampler(render3d_st: mut Render3dState, min_f: int, mag_f: int, wra
   let out = bytes(8)
   let zero: long = 0
   render3d_st.gvk_mk_smp += 1
-  let r = Vk.create_sampler(render3d_st.gvk_dev, sci, null, out)
+  let r = Vk.create_sampler(render3d_st.gvk_dev, sci, render3d_st.gvk_ac, out)
   if r != VK_SUCCESS { gvk_fail(render3d_st, "vkCreateSampler", r);  return zero }
   let s = gvk_handle(out)
   push(ks, min_f);  push(ks, mag_f);  push(ks, wrap_s);  push(ks, wrap_t);  push(ks, compare);  push(ks, aniso);  push(ks, bias)
@@ -673,7 +673,7 @@ function gvk_buf_release(render3d_st: mut Render3dState, b: int) -> void {
     push(render3d_st.gvk_retired_frame, render3d_st.gvk_buf_used[b])
   } else {
     render3d_st.gvk_mk_x_buf += 1
-    Vk.destroy_buffer(render3d_st.gvk_dev, render3d_st.gvk_buf[b], null)
+    Vk.destroy_buffer(render3d_st.gvk_dev, render3d_st.gvk_buf[b], render3d_st.gvk_ac)
     gvk_mem_free(render3d_st, gvk_mem_id(render3d_st.gvk_buf_mem[b]))
   }
   render3d_st.gvk_buf[b] = zero;  render3d_st.gvk_buf_mem[b] = zero;  render3d_st.gvk_buf_size[b] = 0;  render3d_st.gvk_buf_map[b] = null;  render3d_st.gvk_buf_used[b] = 0
@@ -702,7 +702,7 @@ function gvk_retire_upto(render3d_st: mut Render3dState, done: int) -> void {
       w += 1
     } else {
       render3d_st.gvk_mk_x_buf += 1
-      Vk.destroy_buffer(render3d_st.gvk_dev, render3d_st.gvk_retired_buf[i], null)
+      Vk.destroy_buffer(render3d_st.gvk_dev, render3d_st.gvk_retired_buf[i], render3d_st.gvk_ac)
       gvk_mem_free(render3d_st, gvk_mem_id(render3d_st.gvk_retired_mem[i]))
     }
   }
@@ -741,14 +741,14 @@ function gvk_buf_reserve(render3d_st: mut Render3dState, b: int, n: int) -> bool
   Vk.put_i32(bci, VkBufferCreateInfo_sharingMode, VK_SHARING_MODE_EXCLUSIVE)
   let out = gvk_tmp(render3d_st, 8)
   render3d_st.gvk_mk_buf += 1
-  var r = Vk.create_buffer(render3d_st.gvk_dev, bci, null, out)
+  var r = Vk.create_buffer(render3d_st.gvk_dev, bci, render3d_st.gvk_ac, out)
   if r != VK_SUCCESS { return gvk_fail(render3d_st, `vkCreateBuffer ({size} bytes)`, r) }
   let buf = gvk_handle(out)
   let req = gvk_tmp(render3d_st, VkMemoryRequirements_sizeof)
   Vk.get_buffer_memory_requirements(render3d_st.gvk_dev, buf, req)
   let ma = gvk_mem_new(render3d_st, req, VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT, false)
   let zero: long = 0
-  if ma == 0 { Vk.destroy_buffer(render3d_st.gvk_dev, buf, null);  return false }
+  if ma == 0 { Vk.destroy_buffer(render3d_st.gvk_dev, buf, render3d_st.gvk_ac);  return false }
   let mem: long = ma
   r = Vk.bind_buffer_memory(render3d_st.gvk_dev, buf, gvk_mem_handle(render3d_st, ma), gvk_mem_offset(render3d_st, ma))
   if r != VK_SUCCESS { return gvk_fail(render3d_st, "vkBindBufferMemory", r) }
@@ -810,13 +810,13 @@ function gvk_prime_target(render3d_st: mut Render3dState) -> bool {
   Vk.put_i32(bci, VkBufferCreateInfo_usage, VK_BUFFER_USAGE_TRANSFER_DST_BIT)
   Vk.put_i32(bci, VkBufferCreateInfo_sharingMode, VK_SHARING_MODE_EXCLUSIVE)
   let out = gvk_tmp(render3d_st, 8)
-  if Vk.create_buffer(render3d_st.gvk_dev, bci, null, out) != VK_SUCCESS { return false }
+  if Vk.create_buffer(render3d_st.gvk_dev, bci, render3d_st.gvk_ac, out) != VK_SUCCESS { return false }
   let buf = gvk_handle(out)
   let req = gvk_tmp(render3d_st, VkMemoryRequirements_sizeof)
   Vk.get_buffer_memory_requirements(render3d_st.gvk_dev, buf, req)
   let ma = gvk_mem_new(render3d_st, req, VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT, false)
   if ma == 0 {
-    Vk.destroy_buffer(render3d_st.gvk_dev, buf, null)
+    Vk.destroy_buffer(render3d_st.gvk_dev, buf, render3d_st.gvk_ac)
     return false
   }
   Vk.bind_buffer_memory(render3d_st.gvk_dev, buf, gvk_mem_handle(render3d_st, ma), gvk_mem_offset(render3d_st, ma))
diff --git a/runtime/native/vk.ludic b/runtime/native/vk.ludic
index cb5dc026..e85d9f72 100644
--- a/runtime/native/vk.ludic
+++ b/runtime/native/vk.ludic
@@ -30,6 +30,11 @@ import "vk_api.ludic"
 extern function vk_frame_pool() = "lvk_frame_pool"
 # malloc's live bytes (macOS; 0 elsewhere): a test that a path allocates nothing, frame after frame
 extern function vk_heap_bytes() -> long = "lvk_heap_bytes"
+# the VkAllocationCallbacks that count MoltenVK's host allocations (memory plan 25.1c; null on
+# Windows), and what they count: live bytes now, and per VkSystemAllocationScope
+extern function vk_alloc_callbacks() -> pointer = "lvk_ac_ptr"
+extern function vk_alloc_bytes() -> long = "lvk_ac_bytes"
+extern function vk_alloc_scope_bytes(scope: int) -> long = "lvk_ac_scope_bytes"
 extern function vk_sl_prefer(on: int) = "lvk_sl_prefer"
 extern function vk_sl_active() -> int = "lvk_sl_active"
 extern function vk_sl_init(pref: pointer, sdk_version: long) -> int = "lsl_slInit"
diff --git a/runtime/native/vk_mac.ll b/runtime/native/vk_mac.ll
index 2f7732a4..5f768280 100644
--- a/runtime/native/vk_mac.ll
+++ b/runtime/native/vk_mac.ll
@@ -264,3 +264,144 @@ entry:
   %n = load i64, ptr %p
   ret i64 %n
 }
+
+; VkAllocationCallbacks (memory plan 25.1c): render3d hands @lvk_ac to every Vulkan create and
+; destroy when R3D_ALLOC_VK=1, so MoltenVK's own host allocations are counted - live bytes, the peak,
+; allocations made and bytes per VkSystemAllocationScope - for the fence to read (lvk_ac_*).
+; Metal's own allocations are never seen here. libc underneath, never the fence's allocator. Each
+; block carries a 16-byte header before it: scope (i32), the offset to malloc's block (i32), size
+; (i64); the offset is the alignment asked, at least 16, so the block keeps it. The counters are
+; atomics: MoltenVK allocates from its completion handlers' threads too.
+@lvk_ac_live = global i64 0
+@lvk_ac_peak_v = global i64 0
+@lvk_ac_n = global i64 0
+@lvk_ac_scope = global [5 x i64] zeroinitializer
+@lvk_ac = global [6 x ptr] [ptr null, ptr @lvk_ac_alloc, ptr @lvk_ac_realloc, ptr @lvk_ac_free, ptr null, ptr null]
+declare i32 @posix_memalign(ptr, i64, i64)
+declare void @free(ptr)
+declare ptr @memcpy(ptr, ptr, i64)
+
+define internal void @lvk_ac_count(i32 %scope, i64 %d, i64 %n) {
+entry:
+  %old = atomicrmw add ptr @lvk_ac_live, i64 %d seq_cst
+  %new = add i64 %old, %d
+  %pk = atomicrmw max ptr @lvk_ac_peak_v, i64 %new seq_cst
+  %nn = atomicrmw add ptr @lvk_ac_n, i64 %n seq_cst
+  %lo = icmp slt i32 %scope, 0
+  %hi = icmp sgt i32 %scope, 4
+  %bad = or i1 %lo, %hi
+  %sc = select i1 %bad, i32 1, i32 %scope
+  %sp = getelementptr [5 x i64], ptr @lvk_ac_scope, i32 0, i32 %sc
+  %sv = atomicrmw add ptr %sp, i64 %d seq_cst
+  ret void
+}
+define internal ptr @lvk_ac_alloc(ptr %ud, i64 %size, i64 %align, i32 %scope) {
+entry:
+  %z = icmp eq i64 %size, 0
+  br i1 %z, label %none, label %go
+none:
+  ret ptr null
+go:
+  %small = icmp ult i64 %align, 16
+  %a = select i1 %small, i64 16, i64 %align
+  %tot = add i64 %size, %a
+  %slot = alloca ptr, align 8
+  %r = call i32 @posix_memalign(ptr %slot, i64 %a, i64 %tot)
+  %ok = icmp eq i32 %r, 0
+  br i1 %ok, label %have, label %none
+have:
+  %base = load ptr, ptr %slot
+  %p = getelementptr i8, ptr %base, i64 %a
+  %h = getelementptr i8, ptr %p, i64 -16
+  store i32 %scope, ptr %h
+  %ha = getelementptr i8, ptr %h, i64 4
+  %a32 = trunc i64 %a to i32
+  store i32 %a32, ptr %ha
+  %hs = getelementptr i8, ptr %h, i64 8
+  store i64 %size, ptr %hs
+  call void @lvk_ac_count(i32 %scope, i64 %size, i64 1)
+  ret ptr %p
+}
+define internal void @lvk_ac_free(ptr %ud, ptr %p) {
+entry:
+  %z = icmp eq ptr %p, null
+  br i1 %z, label %done, label %go
+done:
+  ret void
+go:
+  %h = getelementptr i8, ptr %p, i64 -16
+  %scope = load i32, ptr %h
+  %ha = getelementptr i8, ptr %h, i64 4
+  %a32 = load i32, ptr %ha
+  %hs = getelementptr i8, ptr %h, i64 8
+  %size = load i64, ptr %hs
+  %neg = sub i64 0, %size
+  call void @lvk_ac_count(i32 %scope, i64 %neg, i64 0)
+  %a = zext i32 %a32 to i64
+  %na = sub i64 0, %a
+  %base = getelementptr i8, ptr %p, i64 %na
+  call void @free(ptr %base)
+  ret void
+}
+; a new block at the asked alignment, the old one's bytes copied, the old one freed: realloc itself
+; only keeps 16
+define internal ptr @lvk_ac_realloc(ptr %ud, ptr %old, i64 %size, i64 %align, i32 %scope) {
+entry:
+  %nold = icmp eq ptr %old, null
+  br i1 %nold, label %fresh, label %chk
+fresh:
+  %f = call ptr @lvk_ac_alloc(ptr %ud, i64 %size, i64 %align, i32 %scope)
+  ret ptr %f
+chk:
+  %z = icmp eq i64 %size, 0
+  br i1 %z, label %drop, label %move
+drop:
+  call void @lvk_ac_free(ptr %ud, ptr %old)
+  ret ptr null
+move:
+  %nb = call ptr @lvk_ac_alloc(ptr %ud, i64 %size, i64 %align, i32 %scope)
+  %nz = icmp eq ptr %nb, null
+  br i1 %nz, label %fail, label %copy
+fail:
+  ret ptr null
+copy:
+  %hs = getelementptr i8, ptr %old, i64 -8
+  %osz = load i64, ptr %hs
+  %less = icmp ult i64 %osz, %size
+  %n = select i1 %less, i64 %osz, i64 %size
+  %cp = call ptr @memcpy(ptr %nb, ptr %old, i64 %n)
+  call void @lvk_ac_free(ptr %ud, ptr %old)
+  ret ptr %nb
+}
+define ptr @lvk_ac_ptr() {
+entry:
+  ret ptr @lvk_ac
+}
+define i64 @lvk_ac_bytes() {
+entry:
+  %v = load atomic i64, ptr @lvk_ac_live seq_cst, align 8
+  ret i64 %v
+}
+define i64 @lvk_ac_peak() {
+entry:
+  %v = load atomic i64, ptr @lvk_ac_peak_v seq_cst, align 8
+  ret i64 %v
+}
+define i64 @lvk_ac_allocs() {
+entry:
+  %v = load atomic i64, ptr @lvk_ac_n seq_cst, align 8
+  ret i64 %v
+}
+define i64 @lvk_ac_scope_bytes(i32 %scope) {
+entry:
+  %lo = icmp slt i32 %scope, 0
+  %hi = icmp sgt i32 %scope, 4
+  %bad = or i1 %lo, %hi
+  br i1 %bad, label %none, label %read
+none:
+  ret i64 0
+read:
+  %sp = getelementptr [5 x i64], ptr @lvk_ac_scope, i32 0, i32 %scope
+  %v = load atomic i64, ptr %sp seq_cst, align 8
+  ret i64 %v
+}
diff --git a/runtime/native/vk_win.ll b/runtime/native/vk_win.ll
index a3ae3f37..5567d367 100644
--- a/runtime/native/vk_win.ll
+++ b/runtime/native/vk_win.ll
@@ -375,3 +375,26 @@ define i64 @lvk_heap_bytes() {
 entry:
   ret i64 0
 }
+
+; VkAllocationCallbacks (memory plan 25.1c): not measured on Windows yet - render3d gets null and
+; passes it, and the fence reads 0 (the residual there is a later step).
+define ptr @lvk_ac_ptr() {
+entry:
+  ret ptr null
+}
+define i64 @lvk_ac_bytes() {
+entry:
+  ret i64 0
+}
+define i64 @lvk_ac_peak() {
+entry:
+  ret i64 0
+}
+define i64 @lvk_ac_allocs() {
+entry:
+  ret i64 0
+}
+define i64 @lvk_ac_scope_bytes(i32 %scope) {
+entry:
+  ret i64 0
+}