- updateTaskPlanAction: requireProductWriter, Zod validation, tenant-guard, revalidatePath
- TaskDetailContent component keyed by task.id avoids setState-in-effect pattern
- Save-on-blur: "Bezig met opslaan…" → "Opgeslagen" (fades after 2s)
- DemoTooltip + readOnly for demo users; error toast on failure
- Footer link "Open in Sprint Board ↗"; updates Zustand store on save
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>