Extract retained stroke preview setup planner

docs/modernization/tasks.md

@@ -509,6 +509,16 @@ Done Checks:
 
 Progress Notes:
 
+- 2026-06-13: `NodeStrokePreview::draw_stroke_immediate()` now routes preview
+  stroke max-size fallback, dual-preview max-size derivation, pattern-scale
+  flips, and Bezier preview-point generation through
+  `plan_legacy_node_stroke_preview_stroke_setup(...)`; compositor coverage now
+  also locks the retained stroke-setup curve/pressure intent and
+  pass-sequence request-validation short-circuit behavior. The preview node
+  still owns brush object mutation, camera wiring, retained `Stroke`
+  population, and live GL execution. Next slice should target the remaining
+  higher-level preview pass orchestration seam without reopening landed
+  sample, mix, pass-sequence, or final-composite helpers.
 - 2026-06-13: `Canvas::draw_merge()` per-layer blend composite now routes
   merge-RTT unbind, shader setup, optional destination-copy feedback, draw,
   and cleanup ordering through