diff --git a/tests/paint_renderer/compositor_tests.cpp b/tests/paint_renderer/compositor_tests.cpp
index 488ce54..f7cce09 100644
--- a/tests/paint_renderer/compositor_tests.cpp
+++ b/tests/paint_renderer/compositor_tests.cpp
@@ -8,6 +8,7 @@
 #include <cmath>
 #include <cstdint>
 #include <span>
+#include <string>
 #include <string_view>
 #include <vector>
 
@@ -1926,6 +1927,137 @@ void retained_stroke_commit_dilate_copy_uses_layer_scratch_slot(pp::tests::Harne
     PP_EXPECT(h, copy_regions[0].height == 128);
 }
 
+void retained_stroke_commit_runner_preserves_per_face_step_order(pp::tests::Harness& h)
+{
+    const auto sequence = plan_canvas_stroke_commit_sequence(
+        CanvasStrokeCommitRequest {
+            .erase_mode = false,
+            .alpha_locked = false,
+            .selection_mask_active = true,
+            .dual_stroke_enabled = true,
+            .pattern_enabled = true,
+        });
+
+    std::vector<std::string> events;
+    const auto record = [&](std::string_view event, int face_index = -1) {
+        if (face_index >= 0) {
+            events.push_back(std::string(event) + ":" + std::to_string(face_index));
+        } else {
+            events.push_back(std::string(event));
+        }
+    };
+
+    const auto result = pp::panopainter::execute_legacy_canvas_stroke_commit_sequence(
+        pp::panopainter::LegacyCanvasStrokeCommitRequest {
+            .context = "test",
+            .faces = {
+                pp::panopainter::LegacyCanvasStrokeCommitFace { .index = 0, .dirty = true },
+                pp::panopainter::LegacyCanvasStrokeCommitFace { .index = 1, .dirty = false },
+                pp::panopainter::LegacyCanvasStrokeCommitFace { .index = 2, .dirty = true },
+            },
+            .sequence = sequence,
+            .callbacks = {
+                .mark_commit_started = [&]() { record("start"); },
+                .capture_render_state = [&]() { record("capture"); },
+                .prepare_render_state = [&]() { record("prepare"); },
+                .restore_render_state = [&]() { record("restore"); },
+                .publish_history = [&]() { record("publish"); },
+                .capture_timelapse_frame = [&]() { record("timelapse"); },
+                .bind_layer_framebuffer = [&](int face_index) { record("bind-fbo", face_index); },
+                .capture_history_region = [&](int face_index) { record("history", face_index); },
+                .apply_layer_dirty_region = [&](int face_index) { record("dirty", face_index); },
+                .copy_layer_to_commit_destination = [&](int face_index) { record("copy-layer", face_index); },
+                .bind_commit_inputs = [&](int face_index) { record("bind-inputs", face_index); },
+                .execute_erase_composite = [&](int face_index) { record("erase", face_index); },
+                .execute_paint_composite = [&](int face_index) { record("paint", face_index); },
+                .copy_committed_to_dilate_source = [&](int face_index) { record("copy-committed", face_index); },
+                .execute_commit_dilate = [&](int face_index) { record("dilate", face_index); },
+                .unbind_layer_framebuffer = [&](int face_index) { record("unbind-fbo", face_index); },
+            },
+        });
+
+    const std::vector<std::string> expected {
+        "start",
+        "capture",
+        "prepare",
+        "bind-fbo:0",
+        "history:0",
+        "dirty:0",
+        "copy-layer:0",
+        "bind-inputs:0",
+        "paint:0",
+        "copy-committed:0",
+        "dilate:0",
+        "unbind-fbo:0",
+        "bind-fbo:2",
+        "history:2",
+        "dirty:2",
+        "copy-layer:2",
+        "bind-inputs:2",
+        "paint:2",
+        "copy-committed:2",
+        "dilate:2",
+        "unbind-fbo:2",
+        "restore",
+        "publish",
+        "timelapse",
+    };
+
+    PP_EXPECT(h, result.ok);
+    PP_EXPECT(h, result.committed_faces == 2);
+    PP_EXPECT(h, events == expected);
+}
+
+void retained_stroke_commit_copy_skips_missing_layer_scratch_or_invalid_extent(pp::tests::Harness& h)
+{
+    pp::paint_renderer::CanvasStrokeCommitSequencePlan missing_scratch;
+    missing_scratch.texture_binding_count = 1U;
+    missing_scratch.texture_bindings[0] = pp::paint_renderer::CanvasStrokeCommitTextureBindingPlan {
+        .role = CanvasStrokeCommitTextureRole::stroke,
+        .slot = 4,
+    };
+
+    int setup_calls = 0;
+    int active_texture_calls = 0;
+    int bind_layer_scratch_calls = 0;
+    int copy_calls = 0;
+
+    pp::panopainter::copy_legacy_canvas_stroke_commit_to_dilate_source(
+        missing_scratch,
+        [&]() { ++setup_calls; },
+        [&](int) { ++active_texture_calls; },
+        [&]() { ++bind_layer_scratch_calls; },
+        [&](int, int, int, int, int, int) { ++copy_calls; },
+        pp::panopainter::LegacyCanvasStrokeCommitCopyExtent {
+            .width = 256,
+            .height = 128,
+        });
+
+    const auto valid_sequence = plan_canvas_stroke_commit_sequence(
+        CanvasStrokeCommitRequest {
+            .erase_mode = true,
+            .alpha_locked = true,
+            .selection_mask_active = false,
+            .dual_stroke_enabled = false,
+            .pattern_enabled = false,
+        });
+    pp::panopainter::copy_legacy_canvas_stroke_commit_to_dilate_source(
+        valid_sequence,
+        [&]() { ++setup_calls; },
+        [&](int) { ++active_texture_calls; },
+        [&]() { ++bind_layer_scratch_calls; },
+        [&](int, int, int, int, int, int) { ++copy_calls; },
+        pp::panopainter::LegacyCanvasStrokeCommitCopyExtent {
+            .width = 0,
+            .height = 128,
+        });
+
+    PP_EXPECT(h, setup_calls == 0);
+    PP_EXPECT(h, active_texture_calls == 0);
+    PP_EXPECT(h, bind_layer_scratch_calls == 0);
+    PP_EXPECT(h, copy_calls == 0);
+}
+
 void plans_stroke_preview_composite_for_simple_brush(pp::tests::Harness& h)
 {
     const auto plan = plan_stroke_preview_composite(StrokePreviewCompositeRequest {});
@@ -2486,6 +2618,12 @@ int main()
     harness.run(
         "retained_stroke_commit_dilate_copy_uses_layer_scratch_slot",
         retained_stroke_commit_dilate_copy_uses_layer_scratch_slot);
+    harness.run(
+        "retained_stroke_commit_runner_preserves_per_face_step_order",
+        retained_stroke_commit_runner_preserves_per_face_step_order);
+    harness.run(
+        "retained_stroke_commit_copy_skips_missing_layer_scratch_or_invalid_extent",
+        retained_stroke_commit_copy_skips_missing_layer_scratch_or_invalid_extent);
     harness.run("plans_stroke_preview_composite_for_simple_brush", plans_stroke_preview_composite_for_simple_brush);
     harness.run("plans_stroke_preview_composite_with_mixer_input", plans_stroke_preview_composite_with_mixer_input);
     harness.run("plans_stroke_preview_composite_with_dual_input", plans_stroke_preview_composite_with_dual_input);