diff --git a/src/__tests__/sorting.test.ts b/src/__tests__/sorting.test.ts
new file mode 100644
index 0000000..23673bd
--- /dev/null
+++ b/src/__tests__/sorting.test.ts
@@ -0,0 +1,57 @@
+import { describe, it, expect } from 'vitest'
+import type { SelectedPotential, PotentialPriority } from '../types'
+
+const PRIORITY_ORDER: Record<PotentialPriority, number> = {
+    Core: 0,
+    Medium: 1,
+    Optional: 2,
+}
+
+function sortPotentials(potentials: SelectedPotential[]): SelectedPotential[] {
+    return [...potentials].sort((a, b) => {
+        if (a.priority !== b.priority) {
+            return PRIORITY_ORDER[a.priority] - PRIORITY_ORDER[b.priority]
+        }
+        return a.selectionTimestamp - b.selectionTimestamp
+    })
+}
+
+describe('Potential Sorting Logic', () => {
+    it('should sort by priority (Core > Medium > Optional)', () => {
+        const potentials: any[] = [
+            { id: 1, priority: 'Optional', selectionTimestamp: 100 },
+            { id: 2, priority: 'Medium', selectionTimestamp: 200 },
+            { id: 3, priority: 'Core', selectionTimestamp: 300 },
+        ]
+        const sorted = sortPotentials(potentials)
+        expect(sorted[0].id).toBe(3) // Core
+        expect(sorted[1].id).toBe(2) // Medium
+        expect(sorted[2].id).toBe(1) // Optional
+    })
+
+    it('should sort by selection order within the same priority', () => {
+        const potentials: any[] = [
+            { id: 1, priority: 'Medium', selectionTimestamp: 500 },
+            { id: 2, priority: 'Medium', selectionTimestamp: 100 },
+            { id: 3, priority: 'Medium', selectionTimestamp: 300 },
+        ]
+        const sorted = sortPotentials(potentials)
+        expect(sorted[0].id).toBe(2) // Earliest
+        expect(sorted[1].id).toBe(3) // Middle
+        expect(sorted[2].id).toBe(1) // Latest
+    })
+
+    it('should correctly handle mixed priorities and timestamps', () => {
+        const potentials: any[] = [
+            { id: 1, priority: 'Optional', selectionTimestamp: 10 },
+            { id: 2, priority: 'Core', selectionTimestamp: 100 },
+            { id: 3, priority: 'Medium', selectionTimestamp: 5 },
+            { id: 4, priority: 'Medium', selectionTimestamp: 50 },
+        ]
+        const sorted = sortPotentials(potentials)
+        expect(sorted[0].id).toBe(2) // Core
+        expect(sorted[1].id).toBe(3) // Medium (earlier)
+        expect(sorted[2].id).toBe(4) // Medium (later)
+        expect(sorted[3].id).toBe(1) // Optional
+    })
+})
diff --git a/src/components/single-selected.tsx b/src/components/single-selected.tsx
new file mode 100644
index 0000000..946a142
--- /dev/null
+++ b/src/components/single-selected.tsx
@@ -0,0 +1,97 @@
+import { InfoIcon, X } from 'lucide-react'
+import { Slider } from './ui/slider'
+import { Button } from './ui/button'
+import {
+    HybridTooltip,
+    HybridTooltipContent,
+    HybridTooltipTrigger,
+} from './ui/hybrid-tooltip'
+import {
+    Select,
+    SelectContent,
+    SelectItem,
+    SelectTrigger,
+    SelectValue,
+} from './ui/select'
+import type { PotentialPriority, Slot } from '@/types'
+import { useTrekkerStore } from '@/lib/trekker-store'
+import ResponsivePotential from './responsive-potential'
+
+export function SingleSelected({ slot, id }: { slot: Slot; id: number }) {
+    const s = useTrekkerStore((state) => state.potentials[slot][id])
+    const updateLevel = useTrekkerStore((sel) => sel.updateLevel)
+    const removePotential = useTrekkerStore((sel) => sel.removePotential)
+    const updatePriority = useTrekkerStore((sel) => sel.updatePriority)
+
+    if (!s) return null
+
+    return (
+        <div className="flex flex-col gap-2 justify-center">
+            <HybridTooltip>
+                <HybridTooltipTrigger asChild>
+                    <div className="relative">
+                        <ResponsivePotential
+                            key={'selected' + s.imgId + s.id}
+                            rarity={s.rarity}
+                            imgId={s.imgId}
+                            name={s.name}
+                            subIcon={s.subIcon}
+                        />
+                        {s.rarity !== 0 && (
+                            <div className="absolute -top-px left-3 text-xs font-semibold text-indigo-500">
+                                {s.level}
+                            </div>
+                        )}
+
+                        <Button
+                            variant="destructive"
+                            size="icon"
+                            className="absolute -top-1 -right-1 rounded-full size-4 border border-white"
+                            onClick={() => removePotential(slot, s.id)}
+                        >
+                            <X className="size-3" />
+                        </Button>
+                    </div>
+                </HybridTooltipTrigger>
+                <HybridTooltipContent>
+                    <p>{s.briefDesc}</p>
+                </HybridTooltipContent>
+            </HybridTooltip>
+
+            <div className="w-20 space-y-2">
+                <Slider
+                    defaultValue={[s.level || 1]}
+                    step={1}
+                    disabled={s.rarity === 0}
+                    min={1}
+                    max={6}
+                    onValueChange={(newValue: Array<number>) =>
+                        updateLevel(slot, s.id, newValue[0])
+                    }
+                ></Slider>
+                <Select
+                    disabled={s.rarity === 0}
+                    value={s.priority}
+                    onValueChange={(value) =>
+                        updatePriority(slot, id, value as PotentialPriority)
+                    }
+                >
+                    <SelectTrigger className="text-[10px] w-full px-2" size="sm">
+                        <SelectValue placeholder="PotentialPriority" />
+                    </SelectTrigger>
+                    <SelectContent align="start">
+                        <SelectItem className="text-[10px]" value="Core">
+                            Core
+                        </SelectItem>
+                        <SelectItem className="text-[10px]" value="Medium">
+                            Medium
+                        </SelectItem>
+                        <SelectItem className="text-[10px]" value="Optional">
+                            Optional
+                        </SelectItem>
+                    </SelectContent>
+                </Select>
+            </div>
+        </div>
+    )
+}
diff --git a/src/components/ss-potentials.tsx b/src/components/ss-potentials.tsx
index e0b3c7e..31626bf 100644
--- a/src/components/ss-potentials.tsx
+++ b/src/components/ss-potentials.tsx
@@ -1,8 +1,7 @@
 import { memo } from 'react'
-import { InfoIcon, PlusIcon, X } from 'lucide-react'
+import { InfoIcon, PlusIcon } from 'lucide-react'
 import { useShallow } from 'zustand/shallow'
 import ResponsivePotential from './responsive-potential'
-import { Slider } from './ui/slider'
 import { Button } from './ui/button'
 import { ScrollArea, ScrollBar } from './ui/scroll-area'
 import {
@@ -11,13 +10,6 @@ import {
   HybridTooltipProvider,
   HybridTooltipTrigger,
 } from './ui/hybrid-tooltip'
-import {
-  Select,
-  SelectContent,
-  SelectItem,
-  SelectTrigger,
-  SelectValue,
-} from './ui/select'
 import type { PotentialPriority, Slot } from '@/types'
 import {
   Popover,
@@ -25,94 +17,30 @@ import {
   PopoverTrigger,
 } from '@/components/ui/popover'
 import { useTrekkerStore } from '@/lib/trekker-store'
+import { SingleSelected } from './single-selected'
+
+const PRIORITY_ORDER: Record<PotentialPriority, number> = {
+  Core: 0,
+  Medium: 1,
+  Optional: 2,
+}
 
 type SSPotentialsProps = {
   slot: Slot
   type: 'main' | 'support'
 }
 
-function SingleSelected({ slot, id }: { slot: Slot; id: number }) {
-  const s = useTrekkerStore((state) => state.potentials[slot][id])
-  const updateLevel = useTrekkerStore((sel) => sel.updateLevel)
-  const removePotential = useTrekkerStore((sel) => sel.removePotential)
-  const updatePriority = useTrekkerStore((sel) => sel.updatePriority)
-  return (
-    <div className="flex flex-col gap-2 justify-center">
-      <HybridTooltip>
-        <HybridTooltipTrigger asChild>
-          <div className="relative">
-            <ResponsivePotential
-              key={'selected' + s.imgId + s.id}
-              rarity={s.rarity}
-              imgId={s.imgId}
-              name={s.name}
-              subIcon={s.subIcon}
-            />
-            {s.rarity !== 0 && (
-              <div className="absolute -top-px left-3 text-xs font-semibold text-indigo-500">
-                {s.level}
-              </div>
-            )}
-
-            <Button
-              variant="destructive"
-              size="icon"
-              className="absolute -top-1 -right-1 rounded-full size-4 border border-white"
-              onClick={() => removePotential(slot, s.id)}
-            >
-              <X className="size-3" />
-            </Button>
-          </div>
-        </HybridTooltipTrigger>
-        <HybridTooltipContent>
-          <p>{s.briefDesc}</p>
-        </HybridTooltipContent>
-      </HybridTooltip>
-
-      <div className="w-20 space-y-2">
-        <Slider
-          defaultValue={[1]}
-          step={1}
-          disabled={s.rarity === 0}
-          min={1}
-          max={6}
-          onValueChange={(newValue: Array<number>) =>
-            updateLevel(slot, s.id, newValue[0])
-          }
-        ></Slider>
-        <Select
-          disabled={s.rarity === 0}
-          value={s.priority}
-          onValueChange={(value) =>
-            updatePriority(slot, id, value as PotentialPriority)
-          }
-        >
-          <SelectTrigger className="text-[10px] w-full px-2" size="sm">
-            <SelectValue placeholder="PotentialPriority" />
-          </SelectTrigger>
-          <SelectContent align="start">
-            <SelectItem className="text-[10px]" value="Core">
-              Core
-            </SelectItem>
-            <SelectItem className="text-[10px]" value="Medium">
-              Medium
-            </SelectItem>
-            <SelectItem className="text-[10px]" value="Optional">
-              Optional
-            </SelectItem>
-          </SelectContent>
-        </Select>
-      </div>
-    </div>
-  )
-}
-
 function SSPotentials({ slot, type }: SSPotentialsProps) {
   const potentials = useTrekkerStore((s) => s.trekkers[slot]?.potential)
-  const selected = useTrekkerStore(
+  const selectedIds = useTrekkerStore(
     useShallow((s) =>
       Object.values(s.potentials[slot])
-        .sort((a, b) => a.rarity - b.rarity)
+        .sort((a, b) => {
+          if (a.priority !== b.priority) {
+            return PRIORITY_ORDER[a.priority] - PRIORITY_ORDER[b.priority]
+          }
+          return a.selectionTimestamp - b.selectionTimestamp
+        })
         .map((p) => p.id),
     ),
   )
@@ -133,7 +61,7 @@ function SSPotentials({ slot, type }: SSPotentialsProps) {
   const filteredPotentials = potentials
     .filter(
       (p) =>
-        (p.type === type || p.type === 'common') && !selected.includes(p.id),
+        (p.type === type || p.type === 'common') && !selectedIds.includes(p.id),
     )
     .sort((a, b) => a.rarity - b.rarity)
 
@@ -199,7 +127,7 @@ function SSPotentials({ slot, type }: SSPotentialsProps) {
 
         <ScrollArea className="w-full rounded-sm bg-popover border">
           <div className="flex min-h-[180.267px] gap-1 p-2">
-            {selected.length === 0 ? (
+            {selectedIds.length === 0 ? (
               <div className="text-center self-center w-full">
                 <div className="h-20 w-full">
                   <img
@@ -210,8 +138,8 @@ function SSPotentials({ slot, type }: SSPotentialsProps) {
                 Please choose potentials
               </div>
             ) : (
-              selected.map((s) => (
-                <SingleSelected key={'selected' + s} slot={slot} id={s} />
+              selectedIds.map((id) => (
+                <SingleSelected key={'selected' + id} slot={slot} id={id} />
               ))
             )}
           </div>
diff --git a/src/config.ts b/src/config.ts
new file mode 100644
index 0000000..0c9ebb0
--- /dev/null
+++ b/src/config.ts
@@ -0,0 +1,3 @@
+export const CONFIG = {
+  DATA_URL: 'https://raw.githubusercontent.com/maj-rf/StellaSoraData/refs/heads/main/character.json',
+} as const;
diff --git a/src/lib/trekker-store.ts b/src/lib/trekker-store.ts
index 3929036..837cb70 100644
--- a/src/lib/trekker-store.ts
+++ b/src/lib/trekker-store.ts
@@ -46,8 +46,8 @@ export const useTrekkerStore = create<TrekkerState>()((set) => ({
           ...state.potentials[slot],
           [p.id]:
             p.rarity === 0
-              ? { ...p, rarity: 0, priority: 'Core' }
-              : { ...p, level: 1, priority: 'Medium' },
+              ? { ...p, rarity: 0, priority: 'Core', selectionTimestamp: Date.now() }
+              : { ...p, level: 1, priority: 'Medium', selectionTimestamp: Date.now() },
         },
       },
     })),
diff --git a/src/lib/utils.ts b/src/lib/utils.ts
index de87752..e8445f5 100644
--- a/src/lib/utils.ts
+++ b/src/lib/utils.ts
@@ -2,6 +2,7 @@ import { clsx } from 'clsx'
 import { twMerge } from 'tailwind-merge'
 import { snapdom } from '@zumer/snapdom'
 import { useTrekkerStore } from './trekker-store'
+import { CONFIG } from '@/config'
 import type { SnapdomPlugin } from '@zumer/snapdom'
 import type { ClassValue } from 'clsx'
 import type { SSCharacter, TAvatar, Trekkers } from '@/types'
@@ -11,14 +12,14 @@ export function cn(...inputs: Array<ClassValue>) {
 }
 
 export async function fetchCharacters(): Promise<Record<string, SSCharacter>> {
-  const response = await fetch(
-    'https://raw.githubusercontent.com/maj-rf/StellaSoraData/refs/heads/main/character.json',
-  )
+  const response = await fetch(CONFIG.DATA_URL)
   if (!response.ok) {
     throw new Error('Failed to fetch characters')
   }
-  const characters = await response.json()
+  return response.json()
+}
 
+export function initializeDefaultTrekkers(characters: Record<string, SSCharacter>) {
   useTrekkerStore.setState({
     trekkers: {
       main: characters[103],
@@ -26,7 +27,6 @@ export async function fetchCharacters(): Promise<Record<string, SSCharacter>> {
       sub2: characters[111],
     },
   })
-  return characters
 }
 
 export function getTrekkersWithoutPotentials(trekkers: Trekkers) {
diff --git a/src/routes/index.tsx b/src/routes/index.tsx
index 2e5a114..4906f1d 100644
--- a/src/routes/index.tsx
+++ b/src/routes/index.tsx
@@ -3,7 +3,7 @@ import { useRef, useTransition } from 'react'
 import { ResponsiveModal } from '@/components/responsive-modal'
 import SSPotentials from '@/components/ss-potentials'
 import { AvatarSelection } from '@/components/avatar-selection'
-import { downloadImage, fetchCharacters } from '@/lib/utils'
+import { downloadImage, fetchCharacters, initializeDefaultTrekkers } from '@/lib/utils'
 import { Preview } from '@/components/preview'
 import { Button } from '@/components/ui/button'
 import { Loading } from '@/components/loading'
@@ -29,7 +29,11 @@ function AvatarPlaceholder() {
 
 export const Route = createFileRoute('/')({
   component: App,
-  loader: fetchCharacters,
+  loader: async () => {
+    const data = await fetchCharacters()
+    initializeDefaultTrekkers(data)
+    return data
+  },
   pendingComponent: Loading,
 })
 
diff --git a/src/types.ts b/src/types.ts
index 4402c3d..e4b23dc 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -29,14 +29,16 @@ export type PotentialPriority = 'Core' | 'Medium' | 'Optional'
 
 export type SelectedPotential =
   | (SSPotential & {
-      rarity: 0
-      level?: never
-      priority: Extract<PotentialPriority, 'Core'>
-    })
+    rarity: 0
+    level?: never
+    priority: Extract<PotentialPriority, 'Core'>
+    selectionTimestamp: number
+  })
   | (SSPotential & {
-      rarity: 1 | 2
-      level: number
-      priority: PotentialPriority
-    })
+    rarity: 1 | 2
+    level: number
+    priority: PotentialPriority
+    selectionTimestamp: number
+  })
 
 export type SelectedPotentialMap = Record<string, SelectedPotential>