Fixed a small bug on the step sizing

roadmap/README.md

@@ -298,6 +298,12 @@ Each feature below links to a detailed implementation plan in the `features/` di
   - **Dependencies**: None
   - **Effort**: Small
 
+- [ ] **[Reduce Per-Step Allocation](features/39-per-step-allocation.md)**
+  - Two heap allocations per accepted step (stage array, dense coefficients)
+  - Against ~150 ns of arithmetic; matters only for cheap right-hand sides
+  - **Dependencies**: None
+  - **Effort**: Medium
+
 ---
 
 ## Implementation Notes