Route stroke preview material decisions through planner

docs/modernization/debt.md

@@ -18,6 +18,10 @@ agent or engineer to remove them without reconstructing context from chat.
 
 ## Recent Reductions
 
+- 2026-06-12: DEBT-0036 was narrowed again. `NodeStrokePreview` now consumes
+  the same `CanvasStrokeMaterialPlan` boundary for preview dual-brush,
+  each-sample pattern, and composite material decisions. Preview GL draw calls,
+  texture binding details, and pattern scale/offset uniforms remain retained.
 - 2026-06-12: DEBT-0036 was narrowed again. Live `Canvas::stroke_draw`,
   stroke commit, and draw-merge paths now consume `CanvasStrokeMaterialPlan`
   through `plan_legacy_canvas_stroke_material` for destination feedback,

docs/modernization/roadmap.md

@@ -1341,8 +1341,10 @@ destination feedback/copy decisions, and `pp_paint_renderer` owns pure
 stroke material/pass planning for pattern, mixer, dual-brush, and final
 composite texture/uniform intent. Live `Canvas::stroke_draw`, stroke commit,
 and draw-merge paths consume that material plan for destination feedback,
-each-sample pattern, dual-brush, and final composite decisions. Actual retained
+each-sample pattern, dual-brush, and final composite decisions, and
-OpenGL draw execution and preview material wiring remain under `DEBT-0036`.
+`NodeStrokePreview` now consumes the same plan for preview material decisions.
+Actual retained OpenGL draw execution and preview texture-binding details remain
+under `DEBT-0036`.
 It also owns renderer API texture-format to
 OpenGL internal/pixel/component token mapping, including depth-stencil formats,
 for future backend texture objects. `Texture2D` 2D texture binding, upload,

src/node_stroke_preview.cpp

@@ -6,6 +6,7 @@
 #include "bezier.h"
 #include "canvas.h"
 #include "app.h"
+#include "legacy_canvas_stroke_services.h"
 #include "legacy_ui_gl_dispatch.h"
 #include "paint_renderer/compositor.h"
 #include "renderer_gl/opengl_capabilities.h"
@@ -42,6 +43,25 @@ pp::paint_renderer::CanvasStrokeFeedbackPlan stroke_preview_destination_feedback
     return fallback;
 }
 
+pp::paint_renderer::CanvasStrokeMaterialPlan stroke_preview_material_plan(
+    const Brush& brush,
+    bool destination_feedback_needed) noexcept
+{
+    return pp::panopainter::plan_legacy_canvas_stroke_material(
+        pp::paint_renderer::CanvasStrokeMaterialRequest {
+            .destination_feedback_needed = destination_feedback_needed,
+            .pattern_enabled = brush.m_pattern_enabled,
+            .pattern_eachsample = brush.m_pattern_eachsample,
+            .wet_blend = brush.m_tip_wet > 0.F,
+            .mix_blend = brush.m_tip_mix > 0.F,
+            .noise_enabled = brush.m_tip_noise > 0.F,
+            .dual_brush_enabled = brush.m_dual_enabled,
+            .dual_blend_mode = brush.m_dual_blend_mode,
+            .pattern_blend_mode = brush.m_pattern_blend_mode,
+            .dual_alpha = brush.m_dual_opacity,
+        });
+}
+
 void set_active_texture_unit(std::uint32_t unit_index)
 {
     pp::legacy::ui_gl::activate_texture_unit(unit_index, "NodeStrokePreview");
@@ -194,17 +214,18 @@ void NodeStrokePreview::stroke_draw_mix(const glm::vec2& bb_min, const glm::vec2
     ShaderManager::u_int(kShaderUniform::UseFragcoord, false);
     ShaderManager::u_int(kShaderUniform::BlendMode, b->m_blend_mode);
     ShaderManager::u_mat4(kShaderUniform::MVP, glm::ortho(-.5f, .5f, -.5f, .5f, -1.f, 1.f));
-    ShaderManager::u_int(kShaderUniform::UseDual, b->m_dual_enabled);
+    const auto material = stroke_preview_material_plan(*b, false);
-    ShaderManager::u_int(kShaderUniform::UsePattern, b->m_pattern_enabled && !b->m_pattern_eachsample);
+    ShaderManager::u_int(kShaderUniform::UseDual, material.composite_pass.use_dual);
-    ShaderManager::u_int(kShaderUniform::DualBlendMode, b->m_dual_blend_mode);
+    ShaderManager::u_int(kShaderUniform::UsePattern, material.composite_pass.use_pattern);
+    ShaderManager::u_int(kShaderUniform::DualBlendMode, material.composite_pass.dual_blend_mode);
     ShaderManager::u_vec2(kShaderUniform::PatternScale, patt_scale);
     ShaderManager::u_float(kShaderUniform::PatternInvert, b->m_pattern_invert);
     ShaderManager::u_float(kShaderUniform::PatternBright, b->m_pattern_brightness);
     ShaderManager::u_float(kShaderUniform::PatternContrast, b->m_pattern_contrast);
     ShaderManager::u_float(kShaderUniform::PatternDepth, b->m_pattern_depth);
-    ShaderManager::u_int(kShaderUniform::PatternBlendMode, b->m_pattern_blend_mode);
+    ShaderManager::u_int(kShaderUniform::PatternBlendMode, material.composite_pass.pattern_blend_mode);
     ShaderManager::u_vec2(kShaderUniform::PatternOffset, glm::vec2(b->m_pattern_rand_offset ? 0.5f : 0.0f));
-    ShaderManager::u_float(kShaderUniform::DualAlpha, b->m_dual_opacity);
+    ShaderManager::u_float(kShaderUniform::DualAlpha, material.composite_pass.dual_alpha);
 
     m_sampler_linear.bind(0);
     set_active_texture_unit(0U);
@@ -431,6 +452,7 @@ void NodeStrokePreview::draw_stroke_immediate()
     ShaderManager::u_int(kShaderUniform::Tex, 0); // brush
     const auto stroke_feedback = stroke_preview_destination_feedback_plan(m_rtt.getWidth(), m_rtt.getHeight());
     const bool copy_stroke_destination = !stroke_feedback.reads_destination_color;
+    const auto material = stroke_preview_material_plan(*b, copy_stroke_destination);
     if (copy_stroke_destination)
         ShaderManager::u_int(kShaderUniform::TexBG, 1); // bg
     ShaderManager::u_int(kShaderUniform::TexPattern, 2); // pattern
@@ -448,11 +470,11 @@ void NodeStrokePreview::draw_stroke_immediate()
 
     // DRAW DUAL BRUSH
 
-    if (b->m_dual_enabled)
+    if (material.dual_pass.enabled)
     {
         m_rtt.clear();
         ShaderManager::use(kShader::Stroke);
-        ShaderManager::u_int(kShaderUniform::UsePattern, false);
+        ShaderManager::u_int(kShaderUniform::UsePattern, material.dual_pass.uses_pattern);
         ShaderManager::u_float(kShaderUniform::MixAlpha, 0);
         ShaderManager::u_float(kShaderUniform::Wet, 0);
         ShaderManager::u_float(kShaderUniform::Noise, 0);
@@ -502,7 +524,7 @@ void NodeStrokePreview::draw_stroke_immediate()
     // DRAW MAIN BRUSH
 
     ShaderManager::use(kShader::Stroke);
-    ShaderManager::u_int(kShaderUniform::UsePattern, b->m_pattern_enabled && b->m_pattern_eachsample);
+    ShaderManager::u_int(kShaderUniform::UsePattern, material.stroke_pass.uses_pattern);
     ShaderManager::u_float(kShaderUniform::MixAlpha, b->m_tip_mix);
     ShaderManager::u_float(kShaderUniform::Wet, b->m_tip_wet);
     ShaderManager::u_float(kShaderUniform::Noise, b->m_tip_noise);
@@ -566,17 +588,17 @@ void NodeStrokePreview::draw_stroke_immediate()
     ShaderManager::u_int(kShaderUniform::Mask, false);
     ShaderManager::u_int(kShaderUniform::BlendMode, b->m_blend_mode);
     ShaderManager::u_mat4(kShaderUniform::MVP, glm::ortho(-.5f, .5f, -.5f, .5f, -1.f, 1.f));
-    ShaderManager::u_int(kShaderUniform::UseDual, b->m_dual_enabled);
+    ShaderManager::u_int(kShaderUniform::UseDual, material.composite_pass.use_dual);
-    ShaderManager::u_int(kShaderUniform::UsePattern, b->m_pattern_enabled && !b->m_pattern_eachsample);
+    ShaderManager::u_int(kShaderUniform::UsePattern, material.composite_pass.use_pattern);
-    ShaderManager::u_int(kShaderUniform::DualBlendMode, b->m_dual_blend_mode);
+    ShaderManager::u_int(kShaderUniform::DualBlendMode, material.composite_pass.dual_blend_mode);
     ShaderManager::u_vec2(kShaderUniform::PatternScale, patt_scale);
     ShaderManager::u_float(kShaderUniform::PatternInvert, b->m_pattern_invert);
     ShaderManager::u_float(kShaderUniform::PatternBright, b->m_pattern_brightness);
     ShaderManager::u_float(kShaderUniform::PatternContrast, b->m_pattern_contrast);
     ShaderManager::u_float(kShaderUniform::PatternDepth, b->m_pattern_depth);
-    ShaderManager::u_int(kShaderUniform::PatternBlendMode, b->m_pattern_blend_mode);
+    ShaderManager::u_int(kShaderUniform::PatternBlendMode, material.composite_pass.pattern_blend_mode);
     ShaderManager::u_vec2(kShaderUniform::PatternOffset, glm::vec2(b->m_pattern_rand_offset ? 0.5f : 0.0f));
-    ShaderManager::u_float(kShaderUniform::DualAlpha, b->m_dual_opacity);
+    ShaderManager::u_float(kShaderUniform::DualAlpha, material.composite_pass.dual_alpha);
 
     m_sampler_linear.bind(0);
     m_sampler_linear.bind(1);