Route NodeCanvas erase setup through helper

docs/modernization/debt.md

@@ -18,6 +18,11 @@ agent or engineer to remove them without reconstructing context from chat.
 
 ## Recent Reductions
 
+- 2026-06-13: DEBT-0036 was narrowed again. `NodeCanvas` live temporary-erase
+  `CompErase` shader setup now routes through
+  `legacy_canvas_stroke_erase_services.h`; the retained node path still owns
+  per-onion-frame alpha updates, texture binding, temporary erase texture
+  selection, and draw execution.
 - 2026-06-13: DEBT-0036 was narrowed again. `NodeCanvas` live temporary-stroke
   `CompDraw` shader setup now routes through
   `legacy_canvas_stroke_composite_services.h`; the retained node path still

docs/modernization/roadmap.md

@@ -3005,6 +3005,10 @@ Results:
   composite shader setup helper for static `CompDraw` uniforms, while keeping
   per-onion-frame alpha updates, texture binding, temporary stroke texture
   selection, and draw execution in the retained node path.
+- `NodeCanvas` live temporary-erase drawing now uses a retained stroke erase
+  shader setup helper for `CompErase` uniforms, while keeping per-onion-frame
+  alpha updates, texture binding, temporary erase texture selection, and draw
+  execution in the retained node path.
 - `Canvas::stroke_draw_mix` now shares the retained stroke composite shader
   helper for mixer-pass `CompDraw` setup, while preserving its caller-specific
   texture slot uniforms. Mixer framebuffer/scissor state, sampler and texture

src/legacy_canvas_stroke_erase_services.h

@@ -0,0 +1,49 @@
+#pragma once
+
+#include "shader.h"
+
+#include <functional>
+
+namespace pp::panopainter {
+
+struct LegacyStrokeEraseUniforms {
+    glm::mat4 mvp { 1.0f };
+    int texture_slot = 0;
+    int stroke_texture_slot = 1;
+    int mask_texture_slot = 2;
+    bool mask_enabled = false;
+};
+
+struct LegacyStrokeEraseShaderExecution {
+    std::function<void(kShader)> use_shader;
+    std::function<void(kShaderUniform, int)> set_int;
+    std::function<void(kShaderUniform, const glm::mat4&)> set_mat4;
+};
+
+[[nodiscard]] inline LegacyStrokeEraseShaderExecution legacy_shader_manager_stroke_erase_execution() noexcept
+{
+    return {
+        .use_shader = [](kShader shader) { ShaderManager::use(shader); },
+        .set_int = [](kShaderUniform uniform, int value) { ShaderManager::u_int(uniform, value); },
+        .set_mat4 = [](kShaderUniform uniform, const glm::mat4& value) { ShaderManager::u_mat4(uniform, value); },
+    };
+}
+
+inline void setup_legacy_stroke_erase_shader(
+    const LegacyStrokeEraseUniforms& uniforms,
+    const LegacyStrokeEraseShaderExecution& execution) noexcept
+{
+    execution.use_shader(kShader::CompErase);
+    execution.set_int(kShaderUniform::Tex, uniforms.texture_slot);
+    execution.set_int(kShaderUniform::TexStroke, uniforms.stroke_texture_slot);
+    execution.set_int(kShaderUniform::TexMask, uniforms.mask_texture_slot);
+    execution.set_int(kShaderUniform::Mask, uniforms.mask_enabled);
+    execution.set_mat4(kShaderUniform::MVP, uniforms.mvp);
+}
+
+inline void setup_legacy_stroke_erase_shader(const LegacyStrokeEraseUniforms& uniforms)
+{
+    setup_legacy_stroke_erase_shader(uniforms, legacy_shader_manager_stroke_erase_execution());
+}
+
+} // namespace pp::panopainter

src/node_canvas.cpp

@@ -14,6 +14,7 @@
 #include "node_panel_grid.h"
 #include "legacy_canvas_draw_merge_services.h"
 #include "legacy_canvas_stroke_composite_services.h"
+#include "legacy_canvas_stroke_erase_services.h"
 #include "legacy_preference_storage.h"
 #include "legacy_ui_gl_dispatch.h"
 #include "legacy_ui_overlay_services.h"
@@ -485,14 +486,16 @@ void NodeCanvas::draw()
                     m_sampler.bind(1);
                     m_sampler.bind(2);
 
-                    ShaderManager::use(kShader::CompErase);
-                    ShaderManager::u_int(kShaderUniform::Tex, 0);
-                    ShaderManager::u_int(kShaderUniform::TexStroke, 1);
-                    ShaderManager::u_int(kShaderUniform::TexMask, 2);
                     //ShaderManager::u_vec2(kShaderUniform::Resolution, zw(m_canvas->m_box) / zoom);
                     //ShaderManager::u_int(kShaderUniform::Lock, m_canvas->m_layers[layer_index]->m_alpha_locked);
-                    ShaderManager::u_int(kShaderUniform::Mask, m_canvas->m_smask_active);
+                    pp::panopainter::setup_legacy_stroke_erase_shader(
-                    ShaderManager::u_mat4(kShaderUniform::MVP, plane_mvp_z);
+                        pp::panopainter::LegacyStrokeEraseUniforms {
+                            .mvp = plane_mvp_z,
+                            .texture_slot = 0,
+                            .stroke_texture_slot = 1,
+                            .mask_texture_slot = 2,
+                            .mask_enabled = m_canvas->m_smask_active,
+                        });
                     set_active_texture_unit(1);
                     m_canvas->m_tmp[plane_index].bindTexture();
                     set_active_texture_unit(2);