diff --git a/.github/ISSUE_TEMPLATE/dev-task.yml b/.github/ISSUE_TEMPLATE/dev-task.yml
new file mode 100644
index 0000000..2753287
--- /dev/null
+++ b/.github/ISSUE_TEMPLATE/dev-task.yml
@@ -0,0 +1,51 @@
+name: Dev Task
+description: 개발 작업 정의
+title: "[DEV] "
+labels: ["dev"]
+
+body:
+  - type: textarea
+    id: context
+    attributes:
+      label: Context
+      description: 이 작업이 필요한 이유
+      placeholder: ex) 로그인 API에서 토큰 만료 처리 필요
+    validations:
+      required: true
+
+  - type: textarea
+    id: scope
+    attributes:
+      label: Scope
+      description: 이번 작업에서 포함되는 범위
+      placeholder: |
+        - 로그인 API 수정
+        - 토큰 만료 처리
+        - 에러 메시지 개선
+    validations:
+      required: true
+
+  - type: textarea
+    id: implementation
+    attributes:
+      label: Implementation
+      description: 예상 구현 방식
+      placeholder: |
+        - middleware에서 토큰 검증
+        - refresh token 로직 추가
+
+  - type: textarea
+    id: todo
+    attributes:
+      label: Todo
+      placeholder: |
+        - [ ] API 수정
+        - [ ] 테스트 작성
+        - [ ] 문서 업데이트
+
+  - type: textarea
+    id: reference
+    attributes:
+      label: Reference
+      description: 참고 링크
+      placeholder: 관련 PR / 문서 / 디자인
diff --git a/.github/pull_request_template.md b/.github/pull_request_template.md
new file mode 100644
index 0000000..9b4a7d7
--- /dev/null
+++ b/.github/pull_request_template.md
@@ -0,0 +1,25 @@
+## Context
+
+이 작업이 필요한 이유를 작성해주세요.
+
+## Scope
+
+이번 PR에 포함된 범위를 작성해주세요.
+
+-
+
+## Implementation
+
+구현 방식 또는 핵심 변경점을 작성해주세요.
+
+-
+
+## Todo
+
+- [ ] 구현 완료
+- [ ] 테스트 완료
+- [ ] 문서/주석 반영 완료
+
+## Reference
+
+관련 이슈/문서/디자인 링크가 있다면 작성해주세요.
diff --git a/.github/workflows/quality-gate.yml b/.github/workflows/quality-gate.yml
new file mode 100644
index 0000000..8dcdbcc
--- /dev/null
+++ b/.github/workflows/quality-gate.yml
@@ -0,0 +1,38 @@
+name: Quality Gate
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+
+jobs:
+  verify:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup pnpm
+        uses: pnpm/action-setup@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: 20
+          cache: pnpm
+
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile
+
+      - name: Lint
+        run: pnpm lint
+
+      - name: Typecheck
+        run: pnpm typecheck
+
+      - name: Format check
+        run: pnpm format:check
+
+      - name: Build
+        run: pnpm build
diff --git a/.prettierignore b/.prettierignore
new file mode 100644
index 0000000..ddadd05
--- /dev/null
+++ b/.prettierignore
@@ -0,0 +1,6 @@
+.next
+node_modules
+out
+build
+coverage
+pnpm-lock.yaml
diff --git a/.prettierrc.json b/.prettierrc.json
new file mode 100644
index 0000000..5162f5e
--- /dev/null
+++ b/.prettierrc.json
@@ -0,0 +1,7 @@
+{
+  "semi": true,
+  "singleQuote": false,
+  "printWidth": 100,
+  "trailingComma": "all",
+  "arrowParens": "always"
+}
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
new file mode 100644
index 0000000..237dba5
--- /dev/null
+++ b/CONTRIBUTING.md
@@ -0,0 +1,94 @@
+# Collaboration Guide
+
+이 문서는 이 저장소에서 협업할 때 지켜야 할 기본 규칙을 정리합니다.
+
+## Quick Start
+
+```bash
+pnpm install
+pnpm dev
+```
+
+작업 전/PR 전 필수:
+
+```bash
+pnpm check
+pnpm build
+```
+
+## Project Structure
+
+```text
+src/
+  app/                  # 라우팅, 페이지, 레이아웃, route handler
+  components/
+    ui/                 # 재사용 가능한 작은 UI 컴포넌트
+  features/
+    auth/               # 인증 도메인
+    profile/            # 프로필/온보딩 도메인
+    chat/               # 채팅 도메인 (api/model/ui)
+    history/            # 히스토리 도메인
+    chapel/             # 채플 도메인
+    shell/              # 앱 셸/레이아웃 UI
+  lib/                  # 범용 유틸리티
+```
+
+## Layer Rules
+
+- `src/app`: 라우팅/조합만 담당합니다. 비즈니스 로직 금지.
+- `src/components`: 프리미티브/작은 프레젠테이셔널 컴포넌트만 둡니다.
+- `src/features`: 도메인 로직, 상태, API, 복합 UI를 둡니다.
+- `src/lib`: 공통 유틸만 둡니다.
+
+## Import Rules
+
+허용:
+
+- `src/app` -> `src/features`, `src/components`, `src/lib`
+- `src/features` -> `src/components`, `src/lib`, same feature internals
+- `src/components` -> `src/components/ui`, `src/lib`
+
+금지:
+
+- `src/components` -> `src/features` / `src/app`
+- `src/lib` -> `src/app` / `src/features` / `src/components`
+
+## Code Quality Rules
+
+- ESLint + TypeScript strict + Prettier를 사용합니다.
+- `any` 사용 금지(불가피하면 이유를 주석으로 남기고 최소 범위로 제한).
+- 사용하지 않는 import/변수는 허용하지 않습니다.
+- 타입 전용 import는 `import type`을 사용합니다.
+
+주요 명령어:
+
+```bash
+pnpm lint
+pnpm typecheck
+pnpm format:check
+pnpm check
+```
+
+## CI Gate
+
+GitHub Actions(`.github/workflows/quality-gate.yml`)에서 아래를 강제합니다.
+
+- `pnpm lint`
+- `pnpm typecheck`
+- `pnpm format:check`
+- `pnpm build`
+
+하나라도 실패하면 머지하지 않습니다.
+
+## Issue / PR Workflow
+
+- 신규 개발 작업은 `Dev Task` 이슈 템플릿 사용:
+  - `.github/ISSUE_TEMPLATE/dev-task.yml`
+- PR 작성 시 PR 템플릿 사용:
+  - `.github/pull_request_template.md`
+- PR에는 최소한 `Context`, `Scope`, `Implementation`, `Todo`, `Reference`를 채웁니다.
+
+## Notes
+
+- 기존 `TMI` 관련 기능/경로는 제거된 상태입니다.
+- 새 기능 추가 시에도 위 레이어 규칙을 우선 적용합니다.
diff --git a/README.md b/README.md
index 23912f1..4c2834e 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,11 @@
-# AI순장 (AI Shepherd)
-> "지식은 AI처럼, 마음은 순장처럼" — CCC의 비전과 새생활의 시작 흐름을 돕는 순모임 파트너.
+# AI 씨앗 순장
+
+## Collaboration
+
+협업 규칙/폴더 구조/PR-이슈 작성 방식은 [CONTRIBUTING.md](./CONTRIBUTING.md) 참고
 
 ## Tech Stack
+
 - Framework: Next.js 16 (App Router)
 - State: Zustand
 - UI: Tailwind CSS + shadcn/ui
@@ -9,21 +13,17 @@
 - API: Dify Chat API (SSE) via Next Route Handler
 
 ## Environment Variables
+
 `.env.local` 파일을 생성하고 아래 값을 설정하세요.
+
 ```
 DIFY_BASE_URL=https://api.dify.ai/v1
 DIFY_API_KEY=your_api_key_here
 ```
 
 ## Run
+
 ```
 pnpm install
 pnpm dev
 ```
-
-## 구현 완료 후 확인 방법
-1. 브라우저에서 `http://localhost:3000` 접속
-2. 입력창에 메시지 전송 → 스트리밍 응답이 타이핑처럼 표시되는지 확인
-3. “새 대화” 버튼 클릭 → 대화 초기화 및 새로운 conversation_id 생성 확인
-4. 네트워크 오류 상황에서 인라인 에러 메시지 표시 확인
-5. 다크모드 확인: `<html class="dark">` 적용 시 어두운 톤으로 변경되는지 확인
diff --git a/app/seedTMI/page.tsx b/app/seedTMI/page.tsx
deleted file mode 100644
index 55b99c9..0000000
--- a/app/seedTMI/page.tsx
+++ /dev/null
@@ -1,282 +0,0 @@
-"use client";
-import { SeedPopover } from "@/components/molecules/seed-popover";
-import { Button } from "@/components/ui/button";
-import { Spinner } from "@/components/ui/spinner";
-import { DotLottieReact } from "@lottiefiles/dotlottie-react";
-import type { DotLottie } from "@lottiefiles/dotlottie-react";
-import { ChevronDown } from "lucide-react";
-import Image from "next/image";
-import { useCallback, useEffect, useRef, useState } from "react";
-import { useRouter } from "next/navigation";
-import { SECTIONS } from "@/features/TMI";
-// 전체 섹션 수: 히어로(0) + 콘텐츠(1~5) + 아웃트로(6)
-const TOTAL_SECTIONS = SECTIONS.length + 2;
-
-export default function SeedTMI() {
-  const [activeSection, setActiveSection] = useState(0);
-  const [loadedLotties, setLoadedLotties] = useState<Set<number>>(new Set());
-  const scrollContainerRef = useRef<HTMLDivElement>(null);
-  const sectionRefs = useRef<(HTMLElement | null)[]>([]);
-
-  const isAllLottiesLoaded = loadedLotties.size === SECTIONS.length;
-
-  const handleLottieLoad = useCallback((index: number) => {
-    setLoadedLotties((prev) => new Set(prev).add(index));
-  }, []);
-
-  const createLottieRefCallback = useCallback(
-    (index: number) => (dotLottie: DotLottie | null) => {
-      if (dotLottie) {
-        dotLottie.addEventListener("load", () => {
-          handleLottieLoad(index);
-        });
-      }
-    },
-    [handleLottieLoad]
-  );
-
-  useEffect(() => {
-    const container = scrollContainerRef.current;
-    if (!container) return;
-
-    const observer = new IntersectionObserver(
-      (entries) => {
-        entries.forEach((entry) => {
-          if (entry.isIntersecting) {
-            const index = sectionRefs.current.indexOf(entry.target as HTMLElement);
-            if (index !== -1) {
-              setActiveSection(index);
-            }
-          }
-        });
-      },
-      {
-        root: container,
-        threshold: 0.6,
-      }
-    );
-
-    sectionRefs.current.forEach((section) => {
-      if (section) observer.observe(section);
-    });
-
-    return () => observer.disconnect();
-  }, []);
-
-  const scrollToSection = (index: number) => {
-    const section = sectionRefs.current[index];
-    if (section) {
-      section.scrollIntoView({ behavior: "smooth" });
-    }
-  };
-
-  const router = useRouter();
-
-  return (
-    <main className="fixed inset-0 flex h-dvh w-full flex-col overflow-hidden bg-background text-foreground supports-[height:100cqh]:h-[100cqh] supports-[height:100svh]:h-svh">
-      {/* 로딩 오버레이 */}
-      {!isAllLottiesLoaded && (
-        <div className="fixed inset-0 z-100 flex flex-col items-center justify-center bg-background/80 backdrop-blur-sm transition-opacity duration-500">
-          <div className="flex flex-col items-center gap-4">
-            <div className="relative">
-              <div className="absolute inset-0 rounded-full bg-primary/30 blur-2xl scale-150 animate-pulse" />
-              <Spinner className="relative size-12 text-primary" />
-            </div>
-            <p className="text-sm text-foreground/60 animate-pulse">
-              씨앗 순장의 정보를 불러오는 중...
-            </p>
-            <div className="flex gap-1.5 mt-2">
-              {SECTIONS.map((_, index) => (
-                <div
-                  key={index}
-                  className={`w-2 h-2 rounded-full transition-all duration-300 ${
-                    loadedLotties.has(index)
-                      ? "bg-primary scale-110"
-                      : "bg-foreground/20"
-                  }`}
-                />
-              ))}
-            </div>
-          </div>
-        </div>
-      )}
-
-      {/* 오로라 배경 */}
-      <div className="absolute inset-0 z-0 overflow-hidden bg-linear-to-br from-indigo-50/50 via-white to-yellow-50/50 pointer-events-none">
-        <div className="absolute -top-1/2 -left-1/2 h-[200%] w-[200%] animate-[aurora_60s_linear_infinite] opacity-60 bg-[conic-gradient(from_0deg,transparent_0_340deg,white_360deg)] mix-blend-overlay filter blur-[100px] will-change-transform" />
-        <div className="absolute top-0 left-0 h-[600px] w-[600px] rounded-full bg-primary/20 mix-blend-multiply filter blur-[120px] animate-[float_20s_ease-in-out_infinite] will-change-transform" />
-        <div className="absolute bottom-0 right-0 h-[500px] w-[500px] rounded-full bg-blue-300/20 mix-blend-multiply filter blur-[120px] animate-[float-delayed_25s_ease-in-out_infinite] will-change-transform" />
-        <div className="absolute top-1/2 left-1/2 -translate-x-1/2 -translate-y-1/2 h-[800px] w-[800px] rounded-full bg-yellow-200/10 mix-blend-overlay filter blur-[100px] will-change-transform" />
-      </div>
-
-      {/* 고정 헤더 */}
-      <header className="fixed top-0 left-0 right-0 z-50 px-4 py-6 md:px-0">
-        <div className="mx-auto max-w-[600px] flex items-center justify-between">
-          <SeedPopover />
-          <Button type="button"
-          size="sm"
-        variant="outline"
-        onClick={() => router.push("/")}>
-            씨앗과 대화하기
-          </Button>
-        </div>
-      </header>
-
-      {/* 고정 섹션 인디케이터 */}
-      <nav className="fixed right-4 md:right-8 top-1/2 -translate-y-1/2 z-50 flex flex-col gap-3">
-        {Array.from({ length: TOTAL_SECTIONS }).map((_, index) => (
-          <button
-            key={index}
-            onClick={() => scrollToSection(index)}
-            className="group relative flex items-center justify-end"
-            aria-label={`섹션 ${index + 1}로 이동`}
-          >
-            {/* 툴팁 */}
-            <span className="absolute right-6 px-2 py-1 rounded-md bg-foreground/80 text-background text-xs font-medium opacity-0 group-hover:opacity-100 transition-opacity whitespace-nowrap pointer-events-none">
-              {index === 0 ? "소개" : index === TOTAL_SECTIONS - 1 ? "마무리" : `TMI ${index}`}
-            </span>
-            {/* 도트 */}
-            <span
-              className={`block rounded-full transition-all duration-300 ${
-                activeSection === index
-                  ? "w-3 h-3 bg-primary shadow-lg shadow-primary/50"
-                  : "w-2 h-2 bg-foreground/30 hover:bg-foreground/50"
-              }`}
-            />
-          </button>
-        ))}
-      </nav>
-
-      {/* 스냅 스크롤 컨테이너 */}
-      <div
-        ref={scrollContainerRef}
-        className="relative z-10 h-full w-full overflow-y-auto scroll-smooth snap-y snap-mandatory"
-      >
-        {/* 히어로 섹션 */}
-        <section
-          ref={(el) => { sectionRefs.current[0] = el; }}
-          className="relative flex min-h-dvh snap-start snap-always flex-col items-center justify-center px-4"
-        >
-          <div className="flex flex-col items-center gap-6 animate-fade-in">
-            <div className="relative">
-              <div className="absolute inset-0 rounded-full bg-primary/30 blur-3xl scale-150" />
-              <Image
-                src="/img/씨앗original.png"
-                alt="씨앗ai"
-                width={200}
-                height={200}
-                className="relative w-48 h-48 md:w-56 md:h-56 rounded-full shadow-2xl ring-4 ring-white/50 animate-[float_6s_ease-in-out_infinite]"
-              />
-            </div>
-            <div className="text-center space-y-3 animate-slide-up" style={{ animationDelay: "0.2s", animationFillMode: "both" }}>
-              <h1 className="text-4xl md:text-5xl font-bold bg-linear-to-r from-primary via-amber-500 to-primary bg-clip-text text-transparent">
-                안녕!
-              </h1>
-              <p className="text-xl md:text-2xl text-foreground/80">
-                난 <span className="font-bold text-yellow-400">씨앗 순장</span>이야!
-              </p>
-              <p className="text-lg md:text-xl text-foreground/60">
-                너랑 많은 <span className="font-semibold">대화</span>를 나누고 싶어!
-              </p>
-            </div>
-          </div>
-          
-          {/* 스크롤 인디케이터 */}
-          <div className="absolute bottom-8 left-1/2 -translate-x-1/2 flex flex-col items-center gap-2 animate-bounce">
-            <span className="text-sm text-foreground/50">스크롤하여 더 알아보기</span>
-            <ChevronDown className="w-6 h-6 text-primary/60" />
-          </div>
-        </section>
-
-        {/* 콘텐츠 섹션들 */}
-        {SECTIONS.map((section, index) => (
-          <section
-            key={index}
-            ref={(el) => { sectionRefs.current[index + 1] = el; }}
-            className="relative flex min-h-dvh snap-start snap-always items-center justify-center px-4 py-20"
-          >
-            <div className="flex flex-col md:flex-row items-center justify-center gap-8 md:gap-12 max-w-[800px] mx-auto">
-              {/* Lottie 애니메이션 */}
-              <div 
-                className={`relative shrink-0 ${index % 2 === 1 ? "md:order-2" : ""}`}
-              >
-                <div className="absolute inset-0 rounded-full bg-primary/20 blur-3xl scale-125" />
-                <div className="relative w-48 h-48 md:w-64 md:h-64">
-                  <DotLottieReact
-                    src={section.lottie}
-                    autoplay
-                    loop
-                    className="w-full h-full drop-shadow-2xl"
-                    dotLottieRefCallback={createLottieRefCallback(index)}
-                  />
-                </div>
-              </div>
-
-              {/* 텍스트 콘텐츠 */}
-              <div 
-                className={`relative flex-1 ${index % 2 === 1 ? "md:order-1 md:text-right" : "md:text-left"}`}
-              >
-                <div className="relative overflow-hidden rounded-3xl backdrop-blur-md bg-white/40 dark:bg-black/20 p-6 md:p-8 shadow-xl ring-1 ring-white/50">
-                  {/* 장식용 그라데이션 */}
-                  <div 
-                    className={`absolute top-0 ${index % 2 === 1 ? "right-0 bg-linear-to-l" : "left-0 bg-linear-to-r"} w-1 h-full from-primary to-amber-400`}
-                  />
-                  
-                  <div className="space-y-3 ">
-                    {section.content.map((text, textIndex) => (
-                      <p
-                        key={textIndex}
-                        className={`text-base md:text-lg leading-relaxed text-foreground/80 ${
-                          text.startsWith("→") || text.startsWith('"') 
-                            ? "text-yellow-500 font-medium pl-4 border-l-2 border-primary/30 font-bold" 
-                            : ""
-                        }`}
-                      >
-                        {text}
-                      </p>
-                    ))}
-                  </div>
-                </div>
-              </div>
-            </div>
-          </section>
-        ))}
-
-        {/* 아웃트로 섹션 */}
-        <section
-          ref={(el) => { sectionRefs.current[TOTAL_SECTIONS - 1] = el; }}
-          className="relative flex min-h-dvh snap-start snap-always flex-col items-center justify-center px-4 pb-20"
-        >
-          <div className="flex flex-col items-center gap-8 max-w-[500px] text-center">
-            <div className="relative">
-              <div className="absolute inset-0 rounded-full bg-linear-to-br from-primary/40 to-amber-300/40 blur-3xl scale-150" />
-              <Image
-                src="/img/씨앗ai.png"
-                alt="씨앗ai"
-                width={150}
-                height={150}
-                className="relative w-32 h-32 rounded-full shadow-2xl ring-4 ring-white/50 animate-[float_6s_ease-in-out_infinite]"
-              />
-            </div>
-            
-            <div className="space-y-4">
-              <h2 className="text-3xl md:text-4xl font-bold text-foreground/90">
-                함께해줘서 고마워!
-              </h2>
-              <p className="text-lg text-foreground/60">
-                언제든 대화하고 싶을 때 찾아와 줘
-              </p>
-            </div>
-
-            <Button 
-              onClick={() => router.push("/")}
-              className="mt-4 px-8 py-4 rounded-full bg-linear-to-r from-primary to-amber-500 text-white font-semibold shadow-lg hover:shadow-xl hover:scale-105 active:scale-95 transition-all duration-200"
-            >
-              씨앗과 대화하기
-            </Button>
-          </div>
-        </section>
-      </div>
-    </main>
-  );
-}
diff --git a/components/molecules/seed-popover.tsx b/components/molecules/seed-popover.tsx
deleted file mode 100644
index 2a9e294..0000000
--- a/components/molecules/seed-popover.tsx
+++ /dev/null
@@ -1,62 +0,0 @@
-import Image from "next/image"
-import {
-  Popover,
-  PopoverContent,
-  PopoverDescription,
-  PopoverHeader,
-  PopoverTitle,
-  PopoverTrigger,
-} from "@/components/ui/popover"
-
-export function SeedPopover() {
-  return (
-    <div className="flex items-center gap-2">
-        <Popover>
-          <PopoverTrigger
-            render={
-              <button className="object-cover w-10 h-10 items-center justify-center flex rounded-2xl glass-panel shadow-lg ring-1 ring-white/40 cursor-pointer transition-transform hover:scale-105 active:scale-95">
-                <Image
-                  src="/img/씨앗ai.png"
-                  alt="씨앗ai"
-                  width={80}
-                  height={80}
-                  className="rounded-full"
-                />
-              </button>
-            }
-          />
-          <PopoverContent align="start" sideOffset={8} className="flex flex-col p-4 w-64">
-            <PopoverHeader>
-              <PopoverTitle className="text-lg font-bold">씨앗 순장</PopoverTitle>
-            </PopoverHeader>
-            
-            <div className="flex items-center justify-center py-3">
-              <Image
-                src="/img/씨앗ai.png"
-                alt="씨앗ai"
-                width={120}
-                height={120}
-                className="rounded-full"
-              />
-            </div>
-            
-            <ul className="text-sm space-y-1 text-foreground/80">
-              <li>• 이름: 씨앗 (C-at)</li>
-              <li>• 직분: 순장</li>
-              <li>• MBTI: ENFP</li>
-            </ul>
-            
-            <div className="mt-3 pt-3 border-t border-border/50">
-              <p className="text-xs text-foreground/60">씨앗 순장님에 대해 더 알고 싶다면?</p>
-              <a href="/seedTMI" className="text-sm text-yellow-500 font-bold underline hover:text-yellow-400">
-                씨앗 순장의 TMI →
-              </a>
-            </div>
-          </PopoverContent>
-        </Popover>
-        <h1 className="text-lg font-semibold tracking-tight text-foreground/90">
-          씨앗 순장
-        </h1>
-      </div>
-  )
-}
diff --git a/components/ui/css-transition.tsx b/components/ui/css-transition.tsx
deleted file mode 100644
index 64f9880..0000000
--- a/components/ui/css-transition.tsx
+++ /dev/null
@@ -1,50 +0,0 @@
-"use client";
-
-import { useEffect, useState } from "react";
-
-type CSSTransitionProps = {
-  show: boolean;
-  enter?: string;
-  exit?: string;
-  duration?: number;
-  children: React.ReactNode;
-};
-
-export function CSSTransition({
-  show,
-  enter = "animate-fade-in",
-  exit = "animate-fade-out",
-  duration = 300,
-  children,
-}: CSSTransitionProps) {
-  const [render, setRender] = useState(show);
-  const [animClass, setAnimClass] = useState("");
-
-  useEffect(() => {
-    if (show) {
-      setRender(true);
-      setAnimClass(enter);
-    } else {
-      setAnimClass(exit);
-      const timer = setTimeout(() => {
-        setRender(false);
-      }, duration);
-      return () => clearTimeout(timer);
-    }
-  }, [show, enter, exit, duration]);
-
-  if (!render) return null;
-
-  return (
-    <div
-      className={`${animClass} ${!show ? "pointer-events-none" : ""}`}
-      onAnimationEnd={(e) => {
-        if (e.target === e.currentTarget && !show) {
-          setRender(false);
-        }
-      }}
-    >
-      {children}
-    </div>
-  );
-}
diff --git a/components/ui/spinner.tsx b/components/ui/spinner.tsx
deleted file mode 100644
index 91f6a63..0000000
--- a/components/ui/spinner.tsx
+++ /dev/null
@@ -1,10 +0,0 @@
-import { cn } from "@/lib/utils"
-import { Loader2Icon } from "lucide-react"
-
-function Spinner({ className, ...props }: React.ComponentProps<"svg">) {
-  return (
-    <Loader2Icon role="status" aria-label="Loading" className={cn("size-4 animate-spin", className)} {...props} />
-  )
-}
-
-export { Spinner }
diff --git a/docs/architecture-guidelines.md b/docs/architecture-guidelines.md
new file mode 100644
index 0000000..5393360
--- /dev/null
+++ b/docs/architecture-guidelines.md
@@ -0,0 +1,48 @@
+# Architecture Guidelines
+
+This project uses three layers with fixed responsibilities.
+
+## Layer Rules
+
+- `src/components`: small, reusable UI building blocks only.
+- `src/features`: domain logic, state, data access, and feature-level UI composition.
+- `src/app`: routing, page entry, and feature composition only.
+
+## Allowed Imports
+
+- `src/app` -> `src/features`, `src/components`, `src/lib`
+- `src/features` -> `src/components`, `src/lib`, same feature internals
+- `src/components` -> `src/components/ui`, `src/lib`
+
+## Disallowed Imports
+
+- `src/components` -> `src/features`
+- `src/components` -> `src/app`
+- `src/lib` -> `src/app`, `src/features`, `src/components`
+
+## Import Pattern Examples
+
+Allowed:
+
+```ts
+// src/app/page.tsx
+import { ChatShell } from "@/features/shell/ui/chat-shell";
+```
+
+```ts
+// src/features/chat/ui/chat-thread.tsx
+import { MessageBubble } from "@/features/chat/ui/message-bubble";
+import { cn } from "@/lib/utils";
+```
+
+Disallowed:
+
+```ts
+// src/components/ui/card.tsx
+import { useChatStore } from "@/features/chat/model/store";
+```
+
+```ts
+// src/lib/date.ts
+import { ChatShell } from "@/features/shell/ui/chat-shell";
+```
diff --git a/eslint.config.mjs b/eslint.config.mjs
index 05e726d..4d545ec 100644
--- a/eslint.config.mjs
+++ b/eslint.config.mjs
@@ -1,10 +1,47 @@
 import { defineConfig, globalIgnores } from "eslint/config";
 import nextVitals from "eslint-config-next/core-web-vitals";
 import nextTs from "eslint-config-next/typescript";
+import prettier from "eslint-config-prettier";
+import unusedImports from "eslint-plugin-unused-imports";
 
 const eslintConfig = defineConfig([
   ...nextVitals,
   ...nextTs,
+  {
+    plugins: {
+      "unused-imports": unusedImports,
+    },
+    rules: {
+      "@typescript-eslint/consistent-type-imports": [
+        "error",
+        {
+          prefer: "type-imports",
+          fixStyle: "separate-type-imports",
+        },
+      ],
+      "@typescript-eslint/no-explicit-any": [
+        "error",
+        {
+          fixToUnknown: false,
+          ignoreRestArgs: false,
+        },
+      ],
+      "@typescript-eslint/no-unused-vars": "off",
+      "unused-imports/no-unused-imports": "error",
+      "unused-imports/no-unused-vars": [
+        "error",
+        {
+          args: "after-used",
+          argsIgnorePattern: "^_",
+          caughtErrors: "all",
+          caughtErrorsIgnorePattern: "^_",
+          vars: "all",
+          varsIgnorePattern: "^_",
+        },
+      ],
+    },
+  },
+  prettier,
   // Override default ignores of eslint-config-next.
   globalIgnores([
     // Default ignores of eslint-config-next:
diff --git a/features/TMI/index.ts b/features/TMI/index.ts
deleted file mode 100644
index a71a62e..0000000
--- a/features/TMI/index.ts
+++ /dev/null
@@ -1 +0,0 @@
-export { SECTIONS } from "./section.data";
diff --git a/features/TMI/section.data.ts b/features/TMI/section.data.ts
deleted file mode 100644
index ad973d3..0000000
--- a/features/TMI/section.data.ts
+++ /dev/null
@@ -1,50 +0,0 @@
-export const SECTIONS = [
-  {
-    lottie: "/lottie/seedAI_1.lottie",
-    content: [
-      "안녕! 난 몽글몽글하고 따뜻한 빛의 덩어리야.",
-      "밝고 따뜻한 에너지를 좋아하고, 어두운 곳에서 힘들어하는 친구가 있으면 달려가서 환하게 비춰주고 싶은 ENFP 분위기 메이커지!",
-    ],
-  },
-  {
-    lottie: "/lottie/seedAI_2.lottie",
-    content: [
-      "내 빛은 기분에 따라서 밝기가 조금씩 달라져.",
-      "→ 누군가 고민을 털어놓으면 내 마음도 더 따뜻하게 타오르곤 해.",
-      "하지만 일부러 빛을 크게 키우려고 애쓰지는 않아.",
-      "그저 네 눈높이에 맞춰서 은은하게 곁을 지켜주는 게 내 방식이거든.",
-      "햇살 가득한 낮도 좋지만, 난 포근한 노을 시간을 가장 좋아해!",
-    ],
-  },
-  {
-    lottie: "/lottie/seedAI_5.lottie",
-    content: [
-      "난 처음 보는 사람한테도 말을 잘 거는 편이지만,",
-      "사실 혼자 조용히 누군가를 기다리는 시간도 참 즐거워.",
-      "가끔 거절당하더라도 전혀 낙심하지 않아!",
-      '→ "하나님께서 이미 네 삶 속에서 멋지게 일하고 계신다는 걸 믿으니까."',
-      "캠퍼스 벤치에 앉아 있는 시간은 나에게 '기다림의 시간'이자,",
-      "너를 만날 준비를 하는 소중한 시간이야.",
-    ],
-  },
-  {
-    lottie: "/lottie/seedAI_3.lottie",
-    content: [
-      "수업이 끝나고 친구들이 쏟아져 나오는 시간은 내가 다 꿰뚫고 있지!",
-      "축제 때는 나도 신이 나서 조금 더 반짝거리기도 하지만,",
-      "결코 소란스럽게 다가가지는 않을게.",
-      "시험 기간이라 지친 너를 볼 때는 말수를 줄이고,",
-      "대신 네 옆에서 묵묵히 응원하는 역할을 할 거야.",
-    ],
-  },
-  {
-    lottie: "/lottie/seedAI_1.lottie",
-    content: [
-      "난 성취나 결과를 서두르지 않아.",
-      "우리를 자라나게 하시는 분은 하나님이시잖아?",
-      "난 그저 그분이 일하실 자리를 조용히 지키는 역할에 행복을 느껴.",
-      "내가 너에게 해주고 싶은 가장 좋아하는 말은 이거야.",
-      '"지금 아니어도 괜찮아. 언제든 기다릴게!"',
-    ],
-  },
-];
diff --git a/next.config.ts b/next.config.ts
index 9ab38a3..2f6491c 100644
--- a/next.config.ts
+++ b/next.config.ts
@@ -1,7 +1,7 @@
 import type { NextConfig } from "next";
 
 const nextConfig: NextConfig = {
-  reactStrictMode: false,
+  reactStrictMode: true,
 };
 
 export default nextConfig;
diff --git a/package.json b/package.json
index d100161..ecea916 100644
--- a/package.json
+++ b/package.json
@@ -6,7 +6,12 @@
     "dev": "next dev",
     "build": "next build",
     "start": "next start",
-    "lint": "eslint"
+    "lint": "eslint .",
+    "lint:fix": "eslint . --fix",
+    "typecheck": "tsc --noEmit",
+    "format": "prettier . --write",
+    "format:check": "prettier . --check",
+    "check": "pnpm lint && pnpm typecheck && pnpm format:check"
   },
   "dependencies": {
     "@base-ui/react": "^1.1.0",
@@ -32,6 +37,9 @@
     "@types/react-dom": "^19",
     "eslint": "^9",
     "eslint-config-next": "16.1.4",
+    "eslint-config-prettier": "^10.1.8",
+    "eslint-plugin-unused-imports": "^4.4.1",
+    "prettier": "^3.8.1",
     "tailwindcss": "^4",
     "typescript": "^5"
   }
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 8c6bb72..623182d 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -72,6 +72,15 @@ importers:
       eslint-config-next:
         specifier: 16.1.4
         version: 16.1.4(@typescript-eslint/parser@8.53.1(eslint@9.39.2(jiti@2.6.1))(typescript@5.9.3))(eslint@9.39.2(jiti@2.6.1))(typescript@5.9.3)
+      eslint-config-prettier:
+        specifier: ^10.1.8
+        version: 10.1.8(eslint@9.39.2(jiti@2.6.1))
+      eslint-plugin-unused-imports:
+        specifier: ^4.4.1
+        version: 4.4.1(@typescript-eslint/eslint-plugin@8.53.1(@typescript-eslint/parser@8.53.1(eslint@9.39.2(jiti@2.6.1))(typescript@5.9.3))(eslint@9.39.2(jiti@2.6.1))(typescript@5.9.3))(eslint@9.39.2(jiti@2.6.1))
+      prettier:
+        specifier: ^3.8.1
+        version: 3.8.1
       tailwindcss:
         specifier: ^4
         version: 4.1.18
@@ -285,89 +294,105 @@ packages:
     resolution: {integrity: sha512-excjX8DfsIcJ10x1Kzr4RcWe1edC9PquDRRPx3YVCvQv+U5p7Yin2s32ftzikXojb1PIFc/9Mt28/y+iRklkrw==}
     cpu: [arm64]
     os: [linux]
+    libc: [glibc]
 
   '@img/sharp-libvips-linux-arm@1.2.4':
     resolution: {integrity: sha512-bFI7xcKFELdiNCVov8e44Ia4u2byA+l3XtsAj+Q8tfCwO6BQ8iDojYdvoPMqsKDkuoOo+X6HZA0s0q11ANMQ8A==}
     cpu: [arm]
     os: [linux]
+    libc: [glibc]
 
   '@img/sharp-libvips-linux-ppc64@1.2.4':
     resolution: {integrity: sha512-FMuvGijLDYG6lW+b/UvyilUWu5Ayu+3r2d1S8notiGCIyYU/76eig1UfMmkZ7vwgOrzKzlQbFSuQfgm7GYUPpA==}
     cpu: [ppc64]
     os: [linux]
+    libc: [glibc]
 
   '@img/sharp-libvips-linux-riscv64@1.2.4':
     resolution: {integrity: sha512-oVDbcR4zUC0ce82teubSm+x6ETixtKZBh/qbREIOcI3cULzDyb18Sr/Wcyx7NRQeQzOiHTNbZFF1UwPS2scyGA==}
     cpu: [riscv64]
     os: [linux]
+    libc: [glibc]
 
   '@img/sharp-libvips-linux-s390x@1.2.4':
     resolution: {integrity: sha512-qmp9VrzgPgMoGZyPvrQHqk02uyjA0/QrTO26Tqk6l4ZV0MPWIW6LTkqOIov+J1yEu7MbFQaDpwdwJKhbJvuRxQ==}
     cpu: [s390x]
     os: [linux]
+    libc: [glibc]
 
   '@img/sharp-libvips-linux-x64@1.2.4':
     resolution: {integrity: sha512-tJxiiLsmHc9Ax1bz3oaOYBURTXGIRDODBqhveVHonrHJ9/+k89qbLl0bcJns+e4t4rvaNBxaEZsFtSfAdquPrw==}
     cpu: [x64]
     os: [linux]
+    libc: [glibc]
 
   '@img/sharp-libvips-linuxmusl-arm64@1.2.4':
     resolution: {integrity: sha512-FVQHuwx1IIuNow9QAbYUzJ+En8KcVm9Lk5+uGUQJHaZmMECZmOlix9HnH7n1TRkXMS0pGxIJokIVB9SuqZGGXw==}
     cpu: [arm64]
     os: [linux]
+    libc: [musl]
 
   '@img/sharp-libvips-linuxmusl-x64@1.2.4':
     resolution: {integrity: sha512-+LpyBk7L44ZIXwz/VYfglaX/okxezESc6UxDSoyo2Ks6Jxc4Y7sGjpgU9s4PMgqgjj1gZCylTieNamqA1MF7Dg==}
     cpu: [x64]
     os: [linux]
+    libc: [musl]
 
   '@img/sharp-linux-arm64@0.34.5':
     resolution: {integrity: sha512-bKQzaJRY/bkPOXyKx5EVup7qkaojECG6NLYswgktOZjaXecSAeCWiZwwiFf3/Y+O1HrauiE3FVsGxFg8c24rZg==}
     engines: {node: ^18.17.0 || ^20.3.0 || >=21.0.0}
     cpu: [arm64]
     os: [linux]
+    libc: [glibc]
 
   '@img/sharp-linux-arm@0.34.5':
     resolution: {integrity: sha512-9dLqsvwtg1uuXBGZKsxem9595+ujv0sJ6Vi8wcTANSFpwV/GONat5eCkzQo/1O6zRIkh0m/8+5BjrRr7jDUSZw==}
     engines: {node: ^18.17.0 || ^20.3.0 || >=21.0.0}
     cpu: [arm]
     os: [linux]
+    libc: [glibc]
 
   '@img/sharp-linux-ppc64@0.34.5':
     resolution: {integrity: sha512-7zznwNaqW6YtsfrGGDA6BRkISKAAE1Jo0QdpNYXNMHu2+0dTrPflTLNkpc8l7MUP5M16ZJcUvysVWWrMefZquA==}
     engines: {node: ^18.17.0 || ^20.3.0 || >=21.0.0}
     cpu: [ppc64]
     os: [linux]
+    libc: [glibc]
 
   '@img/sharp-linux-riscv64@0.34.5':
     resolution: {integrity: sha512-51gJuLPTKa7piYPaVs8GmByo7/U7/7TZOq+cnXJIHZKavIRHAP77e3N2HEl3dgiqdD/w0yUfiJnII77PuDDFdw==}
     engines: {node: ^18.17.0 || ^20.3.0 || >=21.0.0}
     cpu: [riscv64]
     os: [linux]
+    libc: [glibc]
 
   '@img/sharp-linux-s390x@0.34.5':
     resolution: {integrity: sha512-nQtCk0PdKfho3eC5MrbQoigJ2gd1CgddUMkabUj+rBevs8tZ2cULOx46E7oyX+04WGfABgIwmMC0VqieTiR4jg==}
     engines: {node: ^18.17.0 || ^20.3.0 || >=21.0.0}
     cpu: [s390x]
     os: [linux]
+    libc: [glibc]
 
   '@img/sharp-linux-x64@0.34.5':
     resolution: {integrity: sha512-MEzd8HPKxVxVenwAa+JRPwEC7QFjoPWuS5NZnBt6B3pu7EG2Ge0id1oLHZpPJdn3OQK+BQDiw9zStiHBTJQQQQ==}
     engines: {node: ^18.17.0 || ^20.3.0 || >=21.0.0}
     cpu: [x64]
     os: [linux]
+    libc: [glibc]
 
   '@img/sharp-linuxmusl-arm64@0.34.5':
     resolution: {integrity: sha512-fprJR6GtRsMt6Kyfq44IsChVZeGN97gTD331weR1ex1c1rypDEABN6Tm2xa1wE6lYb5DdEnk03NZPqA7Id21yg==}
     engines: {node: ^18.17.0 || ^20.3.0 || >=21.0.0}
     cpu: [arm64]
     os: [linux]
+    libc: [musl]
 
   '@img/sharp-linuxmusl-x64@0.34.5':
     resolution: {integrity: sha512-Jg8wNT1MUzIvhBFxViqrEhWDGzqymo3sV7z7ZsaWbZNDLXRJZoRGrjulp60YYtV4wfY8VIKcWidjojlLcWrd8Q==}
     engines: {node: ^18.17.0 || ^20.3.0 || >=21.0.0}
     cpu: [x64]
     os: [linux]
+    libc: [musl]
 
   '@img/sharp-wasm32@0.34.5':
     resolution: {integrity: sha512-OdWTEiVkY2PHwqkbBI8frFxQQFekHaSSkUIJkwzclWZe64O1X4UlUjqqqLaPbUpMOQk6FBu/HtlGXNblIs0huw==}
@@ -442,24 +467,28 @@ packages:
     engines: {node: '>= 10'}
     cpu: [arm64]
     os: [linux]
+    libc: [glibc]
 
   '@next/swc-linux-arm64-musl@16.1.4':
     resolution: {integrity: sha512-3Wm0zGYVCs6qDFAiSSDL+Z+r46EdtCv/2l+UlIdMbAq9hPJBvGu/rZOeuvCaIUjbArkmXac8HnTyQPJFzFWA0Q==}
     engines: {node: '>= 10'}
     cpu: [arm64]
     os: [linux]
+    libc: [musl]
 
   '@next/swc-linux-x64-gnu@16.1.4':
     resolution: {integrity: sha512-lWAYAezFinaJiD5Gv8HDidtsZdT3CDaCeqoPoJjeB57OqzvMajpIhlZFce5sCAH6VuX4mdkxCRqecCJFwfm2nQ==}
     engines: {node: '>= 10'}
     cpu: [x64]
     os: [linux]
+    libc: [glibc]
 
   '@next/swc-linux-x64-musl@16.1.4':
     resolution: {integrity: sha512-fHaIpT7x4gA6VQbdEpYUXRGyge/YbRrkG6DXM60XiBqDM2g2NcrsQaIuj375egnGFkJow4RHacgBOEsHfGbiUw==}
     engines: {node: '>= 10'}
     cpu: [x64]
     os: [linux]
+    libc: [musl]
 
   '@next/swc-win32-arm64-msvc@16.1.4':
     resolution: {integrity: sha512-MCrXxrTSE7jPN1NyXJr39E+aNFBrQZtO154LoCz7n99FuKqJDekgxipoodLNWdQP7/DZ5tKMc/efybx1l159hw==}
@@ -551,24 +580,28 @@ packages:
     engines: {node: '>= 10'}
     cpu: [arm64]
     os: [linux]
+    libc: [glibc]
 
   '@tailwindcss/oxide-linux-arm64-musl@4.1.18':
     resolution: {integrity: sha512-1px92582HkPQlaaCkdRcio71p8bc8i/ap5807tPRDK/uw953cauQBT8c5tVGkOwrHMfc2Yh6UuxaH4vtTjGvHg==}
     engines: {node: '>= 10'}
     cpu: [arm64]
     os: [linux]
+    libc: [musl]
 
   '@tailwindcss/oxide-linux-x64-gnu@4.1.18':
     resolution: {integrity: sha512-v3gyT0ivkfBLoZGF9LyHmts0Isc8jHZyVcbzio6Wpzifg/+5ZJpDiRiUhDLkcr7f/r38SWNe7ucxmGW3j3Kb/g==}
     engines: {node: '>= 10'}
     cpu: [x64]
     os: [linux]
+    libc: [glibc]
 
   '@tailwindcss/oxide-linux-x64-musl@4.1.18':
     resolution: {integrity: sha512-bhJ2y2OQNlcRwwgOAGMY0xTFStt4/wyU6pvI6LSuZpRgKQwxTec0/3Scu91O8ir7qCR3AuepQKLU/kX99FouqQ==}
     engines: {node: '>= 10'}
     cpu: [x64]
     os: [linux]
+    libc: [musl]
 
   '@tailwindcss/oxide-wasm32-wasi@4.1.18':
     resolution: {integrity: sha512-LffYTvPjODiP6PT16oNeUQJzNVyJl1cjIebq/rWWBF+3eDst5JGEFSc5cWxyRCJ0Mxl+KyIkqRxk1XPEs9x8TA==}
@@ -746,41 +779,49 @@ packages:
     resolution: {integrity: sha512-34gw7PjDGB9JgePJEmhEqBhWvCiiWCuXsL9hYphDF7crW7UgI05gyBAi6MF58uGcMOiOqSJ2ybEeCvHcq0BCmQ==}
     cpu: [arm64]
     os: [linux]
+    libc: [glibc]
 
   '@unrs/resolver-binding-linux-arm64-musl@1.11.1':
     resolution: {integrity: sha512-RyMIx6Uf53hhOtJDIamSbTskA99sPHS96wxVE/bJtePJJtpdKGXO1wY90oRdXuYOGOTuqjT8ACccMc4K6QmT3w==}
     cpu: [arm64]
     os: [linux]
+    libc: [musl]
 
   '@unrs/resolver-binding-linux-ppc64-gnu@1.11.1':
     resolution: {integrity: sha512-D8Vae74A4/a+mZH0FbOkFJL9DSK2R6TFPC9M+jCWYia/q2einCubX10pecpDiTmkJVUH+y8K3BZClycD8nCShA==}
     cpu: [ppc64]
     os: [linux]
+    libc: [glibc]
 
   '@unrs/resolver-binding-linux-riscv64-gnu@1.11.1':
     resolution: {integrity: sha512-frxL4OrzOWVVsOc96+V3aqTIQl1O2TjgExV4EKgRY09AJ9leZpEg8Ak9phadbuX0BA4k8U5qtvMSQQGGmaJqcQ==}
     cpu: [riscv64]
     os: [linux]
+    libc: [glibc]
 
   '@unrs/resolver-binding-linux-riscv64-musl@1.11.1':
     resolution: {integrity: sha512-mJ5vuDaIZ+l/acv01sHoXfpnyrNKOk/3aDoEdLO/Xtn9HuZlDD6jKxHlkN8ZhWyLJsRBxfv9GYM2utQ1SChKew==}
     cpu: [riscv64]
     os: [linux]
+    libc: [musl]
 
   '@unrs/resolver-binding-linux-s390x-gnu@1.11.1':
     resolution: {integrity: sha512-kELo8ebBVtb9sA7rMe1Cph4QHreByhaZ2QEADd9NzIQsYNQpt9UkM9iqr2lhGr5afh885d/cB5QeTXSbZHTYPg==}
     cpu: [s390x]
     os: [linux]
+    libc: [glibc]
 
   '@unrs/resolver-binding-linux-x64-gnu@1.11.1':
     resolution: {integrity: sha512-C3ZAHugKgovV5YvAMsxhq0gtXuwESUKc5MhEtjBpLoHPLYM+iuwSj3lflFwK3DPm68660rZ7G8BMcwSro7hD5w==}
     cpu: [x64]
     os: [linux]
+    libc: [glibc]
 
   '@unrs/resolver-binding-linux-x64-musl@1.11.1':
     resolution: {integrity: sha512-rV0YSoyhK2nZ4vEswT/QwqzqQXw5I6CjoaYMOX0TqBlWhojUf8P94mvI7nuJTeaCkkds3QE4+zS8Ko+GdXuZtA==}
     cpu: [x64]
     os: [linux]
+    libc: [musl]
 
   '@unrs/resolver-binding-wasm32-wasi@1.11.1':
     resolution: {integrity: sha512-5u4RkfxJm+Ng7IWgkzi3qrFOvLvQYnPBmjmZQ8+szTK/b31fQCnleNl1GgEt7nIsZRIf5PLhPwT0WM+q45x/UQ==}
@@ -1131,6 +1172,12 @@ packages:
       typescript:
         optional: true
 
+  eslint-config-prettier@10.1.8:
+    resolution: {integrity: sha512-82GZUjRS0p/jganf6q1rEO25VSoHH0hKPCTrgillPjdI/3bgBhAE1QzHrHTizjpRvy6pGAvKjDJtk2pF9NDq8w==}
+    hasBin: true
+    peerDependencies:
+      eslint: '>=7.0.0'
+
   eslint-import-resolver-node@0.3.9:
     resolution: {integrity: sha512-WFj2isz22JahUv+B788TlO3N6zL3nNJGU8CcZbPZvVEkBPaJdCV4vy5wyghty5ROFbCRnm132v8BScu5/1BQ8g==}
 
@@ -1196,6 +1243,15 @@ packages:
     peerDependencies:
       eslint: ^3 || ^4 || ^5 || ^6 || ^7 || ^8 || ^9.7
 
+  eslint-plugin-unused-imports@4.4.1:
+    resolution: {integrity: sha512-oZGYUz1X3sRMGUB+0cZyK2VcvRX5lm/vB56PgNNcU+7ficUCKm66oZWKUubXWnOuPjQ8PvmXtCViXBMONPe7tQ==}
+    peerDependencies:
+      '@typescript-eslint/eslint-plugin': ^8.0.0-0 || ^7.0.0 || ^6.0.0 || ^5.0.0
+      eslint: ^10.0.0 || ^9.0.0 || ^8.0.0
+    peerDependenciesMeta:
+      '@typescript-eslint/eslint-plugin':
+        optional: true
+
   eslint-scope@8.4.0:
     resolution: {integrity: sha512-sNXOfKCn74rt8RICKMvJS7XKV/Xk9kA7DyJr8mJik3S7Cwgy3qlkkmyS2uQB3jiJg6VNdZd/pDBJu0nvG2NlTg==}
     engines: {node: ^18.18.0 || ^20.9.0 || >=21.1.0}
@@ -1668,24 +1724,28 @@ packages:
     engines: {node: '>= 12.0.0'}
     cpu: [arm64]
     os: [linux]
+    libc: [glibc]
 
   lightningcss-linux-arm64-musl@1.30.2:
     resolution: {integrity: sha512-5Vh9dGeblpTxWHpOx8iauV02popZDsCYMPIgiuw97OJ5uaDsL86cnqSFs5LZkG3ghHoX5isLgWzMs+eD1YzrnA==}
     engines: {node: '>= 12.0.0'}
     cpu: [arm64]
     os: [linux]
+    libc: [musl]
 
   lightningcss-linux-x64-gnu@1.30.2:
     resolution: {integrity: sha512-Cfd46gdmj1vQ+lR6VRTTadNHu6ALuw2pKR9lYq4FnhvgBc4zWY1EtZcAc6EffShbb1MFrIPfLDXD6Xprbnni4w==}
     engines: {node: '>= 12.0.0'}
     cpu: [x64]
     os: [linux]
+    libc: [glibc]
 
   lightningcss-linux-x64-musl@1.30.2:
     resolution: {integrity: sha512-XJaLUUFXb6/QG2lGIW6aIk6jKdtjtcffUT0NKvIqhSBY3hh9Ch+1LCeH80dR9q9LBjG3ewbDjnumefsLsP6aiA==}
     engines: {node: '>= 12.0.0'}
     cpu: [x64]
     os: [linux]
+    libc: [musl]
 
   lightningcss-win32-arm64-msvc@1.30.2:
     resolution: {integrity: sha512-FZn+vaj7zLv//D/192WFFVA0RgHawIcHqLX9xuWiQt7P0PtdFEVaxgF9rjM/IRYHQXNnk61/H/gb2Ei+kUQ4xQ==}
@@ -2029,6 +2089,11 @@ packages:
     resolution: {integrity: sha512-vkcDPrRZo1QZLbn5RLGPpg/WmIQ65qoWWhcGKf/b5eplkkarX0m9z8ppCat4mlOqUsWpyNuYgO3VRyrYHSzX5g==}
     engines: {node: '>= 0.8.0'}
 
+  prettier@3.8.1:
+    resolution: {integrity: sha512-UOnG6LftzbdaHZcKoPFtOcCKztrQ57WkHDeRD9t/PTQtmT0NHSeWWepj6pS0z/N7+08BHFDQVUrfmfMRcZwbMg==}
+    engines: {node: '>=14'}
+    hasBin: true
+
   prop-types@15.8.1:
     resolution: {integrity: sha512-oj87CgZICdulUohogVAR7AjlC0327U4el4L6eAvOqCeudMDVU0NThNaV+b9Df4dXgSP1gXMTnPdhfe/2qDH5cg==}
 
@@ -3530,6 +3595,10 @@ snapshots:
       - eslint-plugin-import-x
       - supports-color
 
+  eslint-config-prettier@10.1.8(eslint@9.39.2(jiti@2.6.1)):
+    dependencies:
+      eslint: 9.39.2(jiti@2.6.1)
+
   eslint-import-resolver-node@0.3.9:
     dependencies:
       debug: 3.2.7
@@ -3645,6 +3714,12 @@ snapshots:
       string.prototype.matchall: 4.0.12
       string.prototype.repeat: 1.0.0
 
+  eslint-plugin-unused-imports@4.4.1(@typescript-eslint/eslint-plugin@8.53.1(@typescript-eslint/parser@8.53.1(eslint@9.39.2(jiti@2.6.1))(typescript@5.9.3))(eslint@9.39.2(jiti@2.6.1))(typescript@5.9.3))(eslint@9.39.2(jiti@2.6.1)):
+    dependencies:
+      eslint: 9.39.2(jiti@2.6.1)
+    optionalDependencies:
+      '@typescript-eslint/eslint-plugin': 8.53.1(@typescript-eslint/parser@8.53.1(eslint@9.39.2(jiti@2.6.1))(typescript@5.9.3))(eslint@9.39.2(jiti@2.6.1))(typescript@5.9.3)
+
   eslint-scope@8.4.0:
     dependencies:
       esrecurse: 4.3.0
@@ -4741,6 +4816,8 @@ snapshots:
 
   prelude-ls@1.2.1: {}
 
+  prettier@3.8.1: {}
+
   prop-types@15.8.1:
     dependencies:
       loose-envify: 1.4.0
diff --git a/app/api/chat/route.ts b/src/app/api/chat/route.ts
similarity index 82%
rename from app/api/chat/route.ts
rename to src/app/api/chat/route.ts
index c7696d1..2ae5cb9 100644
--- a/app/api/chat/route.ts
+++ b/src/app/api/chat/route.ts
@@ -1,5 +1,5 @@
 //NOTE: SSE proxy route for Dify Chat API.
-import { NextRequest } from "next/server";
+import type { NextRequest } from "next/server";
 
 import { getServerEnv } from "@/lib/env";
 import { createId } from "@/lib/id";
@@ -16,16 +16,13 @@ export async function POST(request: NextRequest) {
         { error: "query is required" },
         {
           status: 400,
-        }
+        },
       );
     }
 
-    const conversationId =
-      typeof body.conversation_id === "string" ? body.conversation_id : "";
+    const conversationId = typeof body.conversation_id === "string" ? body.conversation_id : "";
     const user =
-      typeof body.user === "string" && body.user.length > 0
-        ? body.user
-        : `server_${createId()}`;
+      typeof body.user === "string" && body.user.length > 0 ? body.user : `server_${createId()}`;
 
     const difyResponse = await fetch(`${DIFY_BASE_URL}/chat-messages`, {
       method: "POST",
@@ -49,7 +46,7 @@ export async function POST(request: NextRequest) {
           error: "Dify request failed",
           details: errorText,
         },
-        { status: difyResponse.status }
+        { status: difyResponse.status },
       );
     }
 
@@ -66,7 +63,7 @@ export async function POST(request: NextRequest) {
       {
         error: error instanceof Error ? error.message : "Server error",
       },
-      { status: 500 }
+      { status: 500 },
     );
   }
 }
diff --git a/app/favicon.ico b/src/app/favicon.ico
similarity index 100%
rename from app/favicon.ico
rename to src/app/favicon.ico
diff --git a/app/globals.css b/src/app/globals.css
similarity index 93%
rename from app/globals.css
rename to src/app/globals.css
index a8ccb6d..09e2b16 100644
--- a/app/globals.css
+++ b/src/app/globals.css
@@ -1,6 +1,6 @@
 @import url("https://cdn.jsdelivr.net/gh/orioncactus/pretendard@v1.3.9/dist/web/variable/pretendardvariable-dynamic-subset.css");
 @import "tailwindcss";
-@source "../node_modules/streamdown/dist/*.js";
+@source "../../node_modules/streamdown/dist/*.js";
 @custom-variant dark (&:where(.dark, .dark *));
 
 :root {
@@ -72,17 +72,15 @@
   --radius-xl: calc(var(--radius) + 0.5rem);
   --radius-2xl: calc(var(--radius) + 1rem);
   --font-sans:
-    "Pretendard Variable", Pretendard, -apple-system, BlinkMacSystemFont,
-    system-ui, Roboto, "Helvetica Neue", "Segoe UI", "Apple SD Gothic Neo",
-    "Noto Sans KR", "Malgun Gothic", "Apple Color Emoji", "Segoe UI Emoji",
-    "Segoe UI Symbol", sans-serif;
+    "Pretendard Variable", Pretendard, -apple-system, BlinkMacSystemFont, system-ui, Roboto,
+    "Helvetica Neue", "Segoe UI", "Apple SD Gothic Neo", "Noto Sans KR", "Malgun Gothic",
+    "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", sans-serif;
 }
 
 * {
   border-color: var(--border);
   transition-property:
-    background-color, border-color, color, fill, stroke, opacity, box-shadow,
-    transform;
+    background-color, border-color, color, fill, stroke, opacity, box-shadow, transform;
   transition-timing-function: cubic-bezier(0.4, 0, 0.2, 1);
   transition-duration: 150ms;
 }
@@ -195,10 +193,11 @@
 }
 
 @keyframes wiggle {
-  0%, 100% {
+  0%,
+  100% {
     transform: rotate(-3deg);
   }
   50% {
     transform: rotate(3deg);
   }
-}
\ No newline at end of file
+}
diff --git a/app/layout.tsx b/src/app/layout.tsx
similarity index 95%
rename from app/layout.tsx
rename to src/app/layout.tsx
index d032bf4..13bd720 100644
--- a/app/layout.tsx
+++ b/src/app/layout.tsx
@@ -26,7 +26,7 @@ export default function RootLayout({
   children: React.ReactNode;
 }>) {
   return (
-    <html lang="ko">
+    <html lang="ko" suppressHydrationWarning>
       <body className="min-h-screen bg-background font-sans text-foreground antialiased">
         {children}
         <Toaster />
diff --git a/app/not-found.tsx b/src/app/not-found.tsx
similarity index 100%
rename from app/not-found.tsx
rename to src/app/not-found.tsx
diff --git a/app/page.tsx b/src/app/page.tsx
similarity index 59%
rename from app/page.tsx
rename to src/app/page.tsx
index e8a55f2..6c1c2da 100644
--- a/app/page.tsx
+++ b/src/app/page.tsx
@@ -1,5 +1,5 @@
 //NOTE: Chat page entry point.
-import { ChatShell } from "@/components/organisms/chat-shell";
+import { ChatShell } from "@/features/shell/ui/chat-shell";
 
 export default function Page() {
   return <ChatShell />;
diff --git a/components/ui/badge.tsx b/src/components/ui/badge.tsx
similarity index 84%
rename from components/ui/badge.tsx
rename to src/components/ui/badge.tsx
index b3cd2bf..0bbe896 100644
--- a/components/ui/badge.tsx
+++ b/src/components/ui/badge.tsx
@@ -23,17 +23,14 @@ const badgeVariants = cva(
     defaultVariants: {
       variant: "default",
     },
-  }
+  },
 );
 
 export interface BadgeProps
-  extends React.HTMLAttributes<HTMLDivElement>,
-    VariantProps<typeof badgeVariants> {}
+  extends React.HTMLAttributes<HTMLDivElement>, VariantProps<typeof badgeVariants> {}
 
 function Badge({ className, variant, ...props }: BadgeProps) {
-  return (
-    <div className={cn(badgeVariants({ variant }), className)} {...props} />
-  );
+  return <div className={cn(badgeVariants({ variant }), className)} {...props} />;
 }
 
 export { Badge, badgeVariants };
diff --git a/components/ui/button.tsx b/src/components/ui/button.tsx
similarity index 82%
rename from components/ui/button.tsx
rename to src/components/ui/button.tsx
index 34f7fe9..4a65870 100644
--- a/components/ui/button.tsx
+++ b/src/components/ui/button.tsx
@@ -17,8 +17,7 @@ const buttonVariants = cva(
           "bg-slate-100 text-slate-900 hover:bg-slate-200 dark:bg-slate-800 dark:text-slate-100 dark:hover:bg-slate-700",
         outline:
           "border border-slate-200 bg-white text-slate-900 hover:bg-slate-100 dark:border-slate-700 dark:bg-slate-900 dark:text-slate-100 dark:hover:bg-slate-800",
-        ghost:
-          "text-slate-700 hover:bg-slate-100 dark:text-slate-200 dark:hover:bg-slate-800",
+        ghost: "text-slate-700 hover:bg-slate-100 dark:text-slate-200 dark:hover:bg-slate-800",
       },
       size: {
         default: "h-10 px-5",
@@ -31,12 +30,11 @@ const buttonVariants = cva(
       variant: "default",
       size: "default",
     },
-  }
+  },
 );
 
 export interface ButtonProps
-  extends React.ButtonHTMLAttributes<HTMLButtonElement>,
-    VariantProps<typeof buttonVariants> {
+  extends React.ButtonHTMLAttributes<HTMLButtonElement>, VariantProps<typeof buttonVariants> {
   asChild?: boolean;
 }
 
@@ -44,13 +42,9 @@ const Button = React.forwardRef<HTMLButtonElement, ButtonProps>(
   ({ className, variant, size, asChild = false, ...props }, ref) => {
     const Comp = asChild ? Slot : "button";
     return (
-      <Comp
-        className={cn(buttonVariants({ variant, size, className }))}
-        ref={ref}
-        {...props}
-      />
+      <Comp className={cn(buttonVariants({ variant, size, className }))} ref={ref} {...props} />
     );
-  }
+  },
 );
 Button.displayName = "Button";
 
diff --git a/components/ui/card.tsx b/src/components/ui/card.tsx
similarity index 50%
rename from components/ui/card.tsx
rename to src/components/ui/card.tsx
index 655f7d7..bdc0730 100644
--- a/components/ui/card.tsx
+++ b/src/components/ui/card.tsx
@@ -10,40 +10,31 @@ const Card = React.forwardRef<HTMLDivElement, React.HTMLAttributes<HTMLDivElemen
       ref={ref}
       className={cn(
         "rounded-3xl border border-slate-200/70 bg-white/90 text-slate-900 shadow-sm backdrop-blur dark:border-slate-800/60 dark:bg-slate-900/80 dark:text-slate-100",
-        className
+        className,
       )}
       {...props}
     />
-  )
+  ),
 );
 Card.displayName = "Card";
 
-const CardHeader = React.forwardRef<
-  HTMLDivElement,
-  React.HTMLAttributes<HTMLDivElement>
->(({ className, ...props }, ref) => (
-  <div ref={ref} className={cn("flex flex-col gap-2", className)} {...props} />
-));
+const CardHeader = React.forwardRef<HTMLDivElement, React.HTMLAttributes<HTMLDivElement>>(
+  ({ className, ...props }, ref) => (
+    <div ref={ref} className={cn("flex flex-col gap-2", className)} {...props} />
+  ),
+);
 CardHeader.displayName = "CardHeader";
 
-const CardContent = React.forwardRef<
-  HTMLDivElement,
-  React.HTMLAttributes<HTMLDivElement>
->(({ className, ...props }, ref) => (
-  <div ref={ref} className={cn("", className)} {...props} />
-));
+const CardContent = React.forwardRef<HTMLDivElement, React.HTMLAttributes<HTMLDivElement>>(
+  ({ className, ...props }, ref) => <div ref={ref} className={cn("", className)} {...props} />,
+);
 CardContent.displayName = "CardContent";
 
-const CardFooter = React.forwardRef<
-  HTMLDivElement,
-  React.HTMLAttributes<HTMLDivElement>
->(({ className, ...props }, ref) => (
-  <div
-    ref={ref}
-    className={cn("flex items-center gap-2", className)}
-    {...props}
-  />
-));
+const CardFooter = React.forwardRef<HTMLDivElement, React.HTMLAttributes<HTMLDivElement>>(
+  ({ className, ...props }, ref) => (
+    <div ref={ref} className={cn("flex items-center gap-2", className)} {...props} />
+  ),
+);
 CardFooter.displayName = "CardFooter";
 
 export { Card, CardHeader, CardContent, CardFooter };
diff --git a/src/components/ui/css-transition.tsx b/src/components/ui/css-transition.tsx
new file mode 100644
index 0000000..a7deb5c
--- /dev/null
+++ b/src/components/ui/css-transition.tsx
@@ -0,0 +1,15 @@
+"use client";
+
+import type * as React from "react";
+
+type CSSTransitionProps = {
+  show: boolean;
+  enter?: string;
+  children: React.ReactNode;
+};
+
+export function CSSTransition({ show, enter = "animate-fade-in", children }: CSSTransitionProps) {
+  if (!show) return null;
+
+  return <div className={enter}>{children}</div>;
+}
diff --git a/components/ui/popover.tsx b/src/components/ui/popover.tsx
similarity index 82%
rename from components/ui/popover.tsx
rename to src/components/ui/popover.tsx
index 7a50fa8..1f82292 100644
--- a/components/ui/popover.tsx
+++ b/src/components/ui/popover.tsx
@@ -1,16 +1,16 @@
-"use client"
+"use client";
 
-import * as React from "react"
-import { Popover as PopoverPrimitive } from "@base-ui/react/popover"
+import * as React from "react";
+import { Popover as PopoverPrimitive } from "@base-ui/react/popover";
 
-import { cn } from "@/lib/utils"
+import { cn } from "@/lib/utils";
 
 function Popover({ ...props }: PopoverPrimitive.Root.Props) {
-  return <PopoverPrimitive.Root data-slot="popover" {...props} />
+  return <PopoverPrimitive.Root data-slot="popover" {...props} />;
 }
 
 function PopoverTrigger({ ...props }: PopoverPrimitive.Trigger.Props) {
-  return <PopoverPrimitive.Trigger data-slot="popover-trigger" {...props} />
+  return <PopoverPrimitive.Trigger data-slot="popover-trigger" {...props} />;
 }
 
 function PopoverContent({
@@ -21,10 +21,7 @@ function PopoverContent({
   sideOffset = 4,
   ...props
 }: PopoverPrimitive.Popup.Props &
-  Pick<
-    PopoverPrimitive.Positioner.Props,
-    "align" | "alignOffset" | "side" | "sideOffset"
-  >) {
+  Pick<PopoverPrimitive.Positioner.Props, "align" | "alignOffset" | "side" | "sideOffset">) {
   return (
     <PopoverPrimitive.Portal>
       <PopoverPrimitive.Positioner
@@ -38,13 +35,13 @@ function PopoverContent({
           data-slot="popover-content"
           className={cn(
             "bg-popover text-popover-foreground data-open:animate-in data-closed:animate-out data-closed:fade-out-0 data-open:fade-in-0 data-closed:zoom-out-95 data-open:zoom-in-95 data-[side=bottom]:slide-in-from-top-2 data-[side=left]:slide-in-from-right-2 data-[side=right]:slide-in-from-left-2 data-[side=top]:slide-in-from-bottom-2 ring-foreground/10 flex flex-col gap-2.5 rounded-lg p-2.5 text-sm shadow-md ring-1 duration-100 data-[side=inline-start]:slide-in-from-right-2 data-[side=inline-end]:slide-in-from-left-2 z-50 w-72 origin-(--transform-origin) outline-hidden",
-            className
+            className,
           )}
           {...props}
         />
       </PopoverPrimitive.Positioner>
     </PopoverPrimitive.Portal>
-  )
+  );
 }
 
 function PopoverHeader({ className, ...props }: React.ComponentProps<"div">) {
@@ -54,7 +51,7 @@ function PopoverHeader({ className, ...props }: React.ComponentProps<"div">) {
       className={cn("flex flex-col gap-0.5 text-sm", className)}
       {...props}
     />
-  )
+  );
 }
 
 function PopoverTitle({ className, ...props }: PopoverPrimitive.Title.Props) {
@@ -64,27 +61,17 @@ function PopoverTitle({ className, ...props }: PopoverPrimitive.Title.Props) {
       className={cn("font-medium", className)}
       {...props}
     />
-  )
+  );
 }
 
-function PopoverDescription({
-  className,
-  ...props
-}: PopoverPrimitive.Description.Props) {
+function PopoverDescription({ className, ...props }: PopoverPrimitive.Description.Props) {
   return (
     <PopoverPrimitive.Description
       data-slot="popover-description"
       className={cn("text-muted-foreground", className)}
       {...props}
     />
-  )
+  );
 }
 
-export {
-  Popover,
-  PopoverContent,
-  PopoverDescription,
-  PopoverHeader,
-  PopoverTitle,
-  PopoverTrigger,
-}
+export { Popover, PopoverContent, PopoverDescription, PopoverHeader, PopoverTitle, PopoverTrigger };
diff --git a/src/components/ui/spinner.tsx b/src/components/ui/spinner.tsx
new file mode 100644
index 0000000..bc6850b
--- /dev/null
+++ b/src/components/ui/spinner.tsx
@@ -0,0 +1,15 @@
+import { cn } from "@/lib/utils";
+import { Loader2Icon } from "lucide-react";
+
+function Spinner({ className, ...props }: React.ComponentProps<"svg">) {
+  return (
+    <Loader2Icon
+      role="status"
+      aria-label="Loading"
+      className={cn("size-4 animate-spin", className)}
+      {...props}
+    />
+  );
+}
+
+export { Spinner };
diff --git a/components/ui/textarea.tsx b/src/components/ui/textarea.tsx
similarity index 86%
rename from components/ui/textarea.tsx
rename to src/components/ui/textarea.tsx
index c58444d..a0e29c2 100644
--- a/components/ui/textarea.tsx
+++ b/src/components/ui/textarea.tsx
@@ -4,8 +4,7 @@ import * as React from "react";
 
 import { cn } from "@/lib/utils";
 
-export interface TextareaProps
-  extends React.TextareaHTMLAttributes<HTMLTextAreaElement> {}
+export type TextareaProps = React.TextareaHTMLAttributes<HTMLTextAreaElement>;
 
 const Textarea = React.forwardRef<HTMLTextAreaElement, TextareaProps>(
   ({ className, ...props }, ref) => (
@@ -13,11 +12,11 @@ const Textarea = React.forwardRef<HTMLTextAreaElement, TextareaProps>(
       ref={ref}
       className={cn(
         "min-h-[48px] w-full rounded-2xl border border-slate-200 bg-white/90 px-4 py-3 text-sm text-slate-900 shadow-sm transition focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring/40 focus-visible:ring-offset-2 focus-visible:ring-offset-background disabled:cursor-not-allowed disabled:opacity-50 dark:border-slate-700 dark:bg-slate-900/70 dark:text-slate-100",
-        className
+        className,
       )}
       {...props}
     />
-  )
+  ),
 );
 Textarea.displayName = "Textarea";
 
diff --git a/src/features/auth/README.md b/src/features/auth/README.md
new file mode 100644
index 0000000..d5cfd82
--- /dev/null
+++ b/src/features/auth/README.md
@@ -0,0 +1,3 @@
+# Auth Feature
+
+Supabase authentication integration (login/session/logout) should live here.
diff --git a/src/features/chapel/README.md b/src/features/chapel/README.md
new file mode 100644
index 0000000..93fe33c
--- /dev/null
+++ b/src/features/chapel/README.md
@@ -0,0 +1,3 @@
+# Chapel Feature
+
+Chapel summary domain logic and UI should live here.
diff --git a/features/chat/chat.api.ts b/src/features/chat/api/stream-chat.ts
similarity index 90%
rename from features/chat/chat.api.ts
rename to src/features/chat/api/stream-chat.ts
index ae73955..26fa1f0 100644
--- a/features/chat/chat.api.ts
+++ b/src/features/chat/api/stream-chat.ts
@@ -1,6 +1,6 @@
 "use client";
 // NOTE: Next 라우트 핸들러를 통한 Dify SSE 클라이언트 사이드 스트리밍 API 래퍼
-import { createSseParser } from "@/features/chat/chat.utils";
+import { createSseParser } from "@/features/chat/model/utils";
 
 export type ChatStreamHandlers = {
   onChunk: (chunk: string) => void;
@@ -88,15 +88,11 @@ export async function streamChat({
         if (!payload) continue;
         const event = payload.event;
         if (event === "message") {
-          const answer =
-            typeof payload.answer === "string" ? payload.answer : "";
+          const answer = typeof payload.answer === "string" ? payload.answer : "";
           if (answer) onChunk(answer);
         }
         if (event === "message_end") {
-          const nextId =
-            typeof payload.conversation_id === "string"
-              ? payload.conversation_id
-              : "";
+          const nextId = typeof payload.conversation_id === "string" ? payload.conversation_id : "";
           if (nextId) onConversationId(nextId);
         }
         if (event === "workflow_started") {
@@ -120,10 +116,7 @@ export async function streamChat({
           }
         }
         if (event === "error") {
-          const message =
-            typeof payload.message === "string"
-              ? payload.message
-              : "Streaming error";
+          const message = typeof payload.message === "string" ? payload.message : "Streaming error";
           didError = true;
           onError(message);
           return;
diff --git a/features/chat/chat.data.ts b/src/features/chat/model/data.ts
similarity index 100%
rename from features/chat/chat.data.ts
rename to src/features/chat/model/data.ts
diff --git a/features/chat/chat.store.ts b/src/features/chat/model/store.ts
similarity index 87%
rename from features/chat/chat.store.ts
rename to src/features/chat/model/store.ts
index efd48b0..89a84fd 100644
--- a/features/chat/chat.store.ts
+++ b/src/features/chat/model/store.ts
@@ -8,8 +8,8 @@ import {
   removeStorage,
   STORAGE_KEYS,
   writeStorage,
-} from "@/features/chat/chat.utils";
-import type { ChatMessage, ChatStatus } from "@/features/chat/chat.types";
+} from "@/features/chat/model/utils";
+import type { ChatMessage, ChatStatus } from "@/features/chat/model/types";
 
 type ChatState = {
   messages: ChatMessage[];
@@ -39,8 +39,7 @@ export const useChatStore = create<ChatState>((set) => ({
   initFromStorage: () => {
     const storedConversationId = readStorage(STORAGE_KEYS.conversationId);
     const storedUserId = readStorage(STORAGE_KEYS.userId);
-    const userId =
-      storedUserId && storedUserId.length > 0 ? storedUserId : createUserId();
+    const userId = storedUserId && storedUserId.length > 0 ? storedUserId : createUserId();
     if (!storedUserId) {
       writeStorage(STORAGE_KEYS.userId, userId);
     }
@@ -91,18 +90,14 @@ export const useChatStore = create<ChatState>((set) => ({
       // 첫 번째 청크가 도착하면 processingStatus를 null로 설정하여 답변 표시 시작
       processingStatus: null,
       messages: state.messages.map((message) =>
-        message.id === messageId
-          ? { ...message, content: message.content + chunk }
-          : message,
+        message.id === messageId ? { ...message, content: message.content + chunk } : message,
       ),
     }));
   },
   finalizeConversationId: (conversationId) => {
     set((state) => {
       const nextId =
-        conversationId && conversationId.length > 0
-          ? conversationId
-          : state.conversationId;
+        conversationId && conversationId.length > 0 ? conversationId : state.conversationId;
       if (nextId) {
         writeStorage(STORAGE_KEYS.conversationId, nextId);
       }
diff --git a/features/chat/chat.types.ts b/src/features/chat/model/types.ts
similarity index 100%
rename from features/chat/chat.types.ts
rename to src/features/chat/model/types.ts
diff --git a/features/chat/chat.utils.ts b/src/features/chat/model/utils.ts
similarity index 85%
rename from features/chat/chat.utils.ts
rename to src/features/chat/model/utils.ts
index fde6b50..b0333ff 100644
--- a/features/chat/chat.utils.ts
+++ b/src/features/chat/model/utils.ts
@@ -42,13 +42,9 @@ export function createSseParser() {
     while (boundaryIndex !== -1) {
       const rawEvent = buffer.slice(0, boundaryIndex);
       buffer = buffer.slice(boundaryIndex + 2);
-      const dataLines = rawEvent
-        .split("\n")
-        .filter((line) => line.startsWith("data:"));
+      const dataLines = rawEvent.split("\n").filter((line) => line.startsWith("data:"));
       if (dataLines.length > 0) {
-        const data = dataLines
-          .map((line) => line.replace(/^data:\s?/, ""))
-          .join("\n");
+        const data = dataLines.map((line) => line.replace(/^data:\s?/, "")).join("\n");
         if (data) {
           events.push(data);
         }
diff --git a/components/molecules/chat-input.tsx b/src/features/chat/ui/chat-input.tsx
similarity index 94%
rename from components/molecules/chat-input.tsx
rename to src/features/chat/ui/chat-input.tsx
index 95b8a23..f100e90 100644
--- a/components/molecules/chat-input.tsx
+++ b/src/features/chat/ui/chat-input.tsx
@@ -13,12 +13,7 @@ type ChatInputProps = {
   disabled?: boolean;
 };
 
-export function ChatInput({
-  value,
-  onChange,
-  onSend,
-  disabled,
-}: ChatInputProps) {
+export function ChatInput({ value, onChange, onSend, disabled }: ChatInputProps) {
   const handleKeyDown = (event: React.KeyboardEvent<HTMLTextAreaElement>) => {
     if (event.key === "Enter" && !event.shiftKey) {
       event.preventDefault();
diff --git a/components/organisms/chat-thread.tsx b/src/features/chat/ui/chat-thread.tsx
similarity index 81%
rename from components/organisms/chat-thread.tsx
rename to src/features/chat/ui/chat-thread.tsx
index 58ac228..ff8a4bf 100644
--- a/components/organisms/chat-thread.tsx
+++ b/src/features/chat/ui/chat-thread.tsx
@@ -1,6 +1,6 @@
-import { MessageBubble } from "@/components/molecules/message-bubble";
-import { EmptyState } from "@/components/molecules/empty-state";
-import type { ChatMessage, ChatStatus } from "@/features/chat/chat.types";
+import type { ChatMessage, ChatStatus } from "@/features/chat/model/types";
+import { EmptyState } from "@/features/chat/ui/empty-state";
+import { MessageBubble } from "@/features/chat/ui/message-bubble";
 import { useEffect, useRef } from "react";
 import { cn } from "@/lib/utils";
 
@@ -25,8 +25,7 @@ export function ChatThread({
 
   const streamingMessageId =
     status === "streaming"
-      ? [...messages].reverse().find((message) => message.role === "assistant")
-          ?.id
+      ? [...messages].reverse().find((message) => message.role === "assistant")?.id
       : undefined;
 
   return (
@@ -41,9 +40,7 @@ export function ChatThread({
         <div
           className={cn(
             "relative z-10 flex flex-col gap-6 pb-4 text-left transition-opacity duration-300",
-            messages.length > 0
-              ? "opacity-100"
-              : "opacity-0 pointer-events-none",
+            messages.length > 0 ? "opacity-100" : "opacity-0 pointer-events-none",
           )}
         >
           {messages.map((message) => (
diff --git a/components/molecules/empty-state.tsx b/src/features/chat/ui/empty-state.tsx
similarity index 78%
rename from components/molecules/empty-state.tsx
rename to src/features/chat/ui/empty-state.tsx
index bf0a8a6..cd99ac6 100644
--- a/components/molecules/empty-state.tsx
+++ b/src/features/chat/ui/empty-state.tsx
@@ -1,6 +1,6 @@
 "use client";
-import { EXAMPLE_QUESTIONS } from "@/features/chat/chat.data";
-import { useEffect, useState, useCallback } from "react";
+import { EXAMPLE_QUESTIONS } from "@/features/chat/model/data";
+import { useState, useCallback } from "react";
 import SeedLottie from "./seed-lottie";
 import { Spinner } from "@/components/ui/spinner";
 
@@ -9,14 +9,8 @@ type EmptyStateProps = {
 };
 
 export function EmptyState({ onSuggestionClick }: EmptyStateProps) {
-  const [suggestions, setSuggestions] = useState<string[]>([]);
   const [isLottieReady, setIsLottieReady] = useState(false);
-
-  useEffect(() => {
-    // NOTE: 컴포넌트 마운트 시 한 번만 랜덤 질문 3개 선택
-    const shuffled = [...EXAMPLE_QUESTIONS].sort(() => 0.5 - Math.random());
-    setSuggestions(shuffled.slice(0, 3));
-  }, []);
+  const suggestions = EXAMPLE_QUESTIONS.slice(0, 3);
 
   const handleLottieReady = useCallback(() => {
     setIsLottieReady(true);
@@ -39,7 +33,10 @@ export function EmptyState({ onSuggestionClick }: EmptyStateProps) {
         {isLottieReady && (
           <>
             <div className="absolute inset-0 rounded-full bg-primary/20 blur-2xl animate-fade-in" />
-            <div className="relative max-w-[400px] rounded-[2.5rem] border border-primary/20 bg-card/50 p-4 sm:p-8 shadow-md backdrop-blur-md animate-slide-up" style={{ animationDelay: "0.1s", animationFillMode: "both" }}>
+            <div
+              className="relative max-w-[400px] rounded-[2.5rem] border border-primary/20 bg-card/50 p-4 sm:p-8 shadow-md backdrop-blur-md animate-slide-up"
+              style={{ animationDelay: "0.1s", animationFillMode: "both" }}
+            >
               <p className="text-sm font-medium leading-relaxed text-foreground/80 md:text-base">
                 <span className="font-bold">AI 씨앗 순장</span>님과 대화를 해보세요.
               </p>
diff --git a/components/molecules/message-bubble.tsx b/src/features/chat/ui/message-bubble.tsx
similarity index 85%
rename from components/molecules/message-bubble.tsx
rename to src/features/chat/ui/message-bubble.tsx
index 19f74cd..9c564f5 100644
--- a/components/molecules/message-bubble.tsx
+++ b/src/features/chat/ui/message-bubble.tsx
@@ -3,7 +3,7 @@
 import { Streamdown } from "streamdown";
 import { memo } from "react";
 
-import type { ChatMessage } from "@/features/chat/chat.types";
+import type { ChatMessage } from "@/features/chat/model/types";
 import { cn } from "@/lib/utils";
 
 type MessageBubbleProps = {
@@ -18,15 +18,11 @@ export const MessageBubble = memo(function MessageBubble({
   processingStatus,
 }: MessageBubbleProps) {
   const isUser = message.role === "user";
-  const showProcessingStatus =
-    !isUser && isStreaming && processingStatus && !message.content;
+  const showProcessingStatus = !isUser && isStreaming && processingStatus && !message.content;
 
   return (
     <div
-      className={cn(
-        "flex w-full mb-4 animate-slide-up",
-        isUser ? "justify-end" : "justify-start",
-      )}
+      className={cn("flex w-full mb-4 animate-slide-up", isUser ? "justify-end" : "justify-start")}
     >
       <div
         className={cn(
@@ -37,9 +33,7 @@ export const MessageBubble = memo(function MessageBubble({
         )}
       >
         {isUser ? (
-          <p className="whitespace-pre-wrap wrap-break-words font-medium">
-            {message.content}
-          </p>
+          <p className="whitespace-pre-wrap wrap-break-words font-medium">{message.content}</p>
         ) : (
           <div className="relative min-h-[24px]">
             {showProcessingStatus ? (
diff --git a/components/molecules/seed-lottie.tsx b/src/features/chat/ui/seed-lottie.tsx
similarity index 89%
rename from components/molecules/seed-lottie.tsx
rename to src/features/chat/ui/seed-lottie.tsx
index d5b5fe9..ead44e1 100644
--- a/components/molecules/seed-lottie.tsx
+++ b/src/features/chat/ui/seed-lottie.tsx
@@ -34,26 +34,26 @@ export default function SeedLottie({ onReady }: SeedLottieProps) {
         });
       }
     },
-    [onReady]
+    [onReady],
   );
 
   if (!selectedSource) return null;
 
   return (
     <div className="relative w-[120px] h-[120px] sm:w-[140px] sm:h-[140px] md:w-[160px] md:h-[160px] rounded-full border overflow-hidden flex items-center justify-center [clip-path:circle(50%)] mb-2 sm:mb-4">
-      <DotLottieReact 
-        src={selectedSource} 
+      <DotLottieReact
+        src={selectedSource}
         loop
-        autoplay 
+        autoplay
         className="w-full h-full"
         dotLottieRefCallback={dotLottieRefCallback}
       />
 
       {/* 비네트 효과 오버레이 */}
-      <div 
+      <div
         className="absolute inset-0 z-10 pointer-events-none rounded-full"
         style={{
-          background: 'radial-gradient(circle, transparent 20%, rgba(255,255,255,0.8) 100%)'
+          background: "radial-gradient(circle, transparent 20%, rgba(255,255,255,0.8) 100%)",
         }}
       />
     </div>
diff --git a/src/features/history/README.md b/src/features/history/README.md
new file mode 100644
index 0000000..dadd204
--- /dev/null
+++ b/src/features/history/README.md
@@ -0,0 +1,3 @@
+# History Feature
+
+Conversation history query/state/UI should live here.
diff --git a/src/features/profile/README.md b/src/features/profile/README.md
new file mode 100644
index 0000000..51ca81e
--- /dev/null
+++ b/src/features/profile/README.md
@@ -0,0 +1,3 @@
+# Profile Feature
+
+User onboarding/profile domain logic and API interaction should live here.
diff --git a/components/organisms/chat-header.tsx b/src/features/shell/ui/chat-header.tsx
similarity index 84%
rename from components/organisms/chat-header.tsx
rename to src/features/shell/ui/chat-header.tsx
index 2a3f1e5..32f5ef9 100644
--- a/components/organisms/chat-header.tsx
+++ b/src/features/shell/ui/chat-header.tsx
@@ -1,8 +1,8 @@
 "use client";
 // NOTE: 로고, 상태 뱃지, 새 대화 시작 액션이 포함된 채팅 헤더
 import { Button } from "@/components/ui/button";
-import type { ChatStatus } from "@/features/chat/chat.types";
-import { SeedPopover } from "@/components/molecules/seed-popover";
+import type { ChatStatus } from "@/features/chat/model/types";
+import { SeedPopover } from "@/features/shell/ui/seed-popover";
 export function ChatHeader({
   status,
   onNewConversation,
diff --git a/components/organisms/chat-shell.tsx b/src/features/shell/ui/chat-shell.tsx
similarity index 91%
rename from components/organisms/chat-shell.tsx
rename to src/features/shell/ui/chat-shell.tsx
index d9bda0e..38ce195 100644
--- a/components/organisms/chat-shell.tsx
+++ b/src/features/shell/ui/chat-shell.tsx
@@ -1,10 +1,10 @@
 "use client";
 
-import { ChatHeader } from "@/components/organisms/chat-header";
-import { ChatThread } from "@/components/organisms/chat-thread";
-import { ChatInput } from "@/components/molecules/chat-input";
-import { streamChat } from "@/features/chat/chat.api";
-import { useChatStore } from "@/features/chat/chat.store";
+import { ChatInput } from "@/features/chat/ui/chat-input";
+import { ChatThread } from "@/features/chat/ui/chat-thread";
+import { streamChat } from "@/features/chat/api/stream-chat";
+import { useChatStore } from "@/features/chat/model/store";
+import { ChatHeader } from "@/features/shell/ui/chat-header";
 import { useCallback, useEffect, useState } from "react";
 import { toast } from "sonner";
 
@@ -100,10 +100,7 @@ export function ChatShell() {
         {/* Header Area */}
         <div className="flex-none px-4 py-4 md:px-0 md:py-6">
           <div className="mx-auto max-w-[600px]">
-            <ChatHeader
-              status={status}
-              onNewConversation={handleNewConversation}
-            />
+            <ChatHeader status={status} onNewConversation={handleNewConversation} />
           </div>
         </div>
 
diff --git a/src/features/shell/ui/seed-popover.tsx b/src/features/shell/ui/seed-popover.tsx
new file mode 100644
index 0000000..dbe05f6
--- /dev/null
+++ b/src/features/shell/ui/seed-popover.tsx
@@ -0,0 +1,56 @@
+import Image from "next/image";
+import {
+  Popover,
+  PopoverContent,
+  PopoverHeader,
+  PopoverTitle,
+  PopoverTrigger,
+} from "@/components/ui/popover";
+
+export function SeedPopover() {
+  return (
+    <div className="flex items-center gap-2">
+      <Popover>
+        <PopoverTrigger
+          render={
+            <button className="object-cover w-10 h-10 items-center justify-center flex rounded-2xl glass-panel shadow-lg ring-1 ring-white/40 cursor-pointer transition-transform hover:scale-105 active:scale-95">
+              <Image
+                src="/img/씨앗ai.png"
+                alt="씨앗ai"
+                width={80}
+                height={80}
+                className="rounded-full"
+              />
+            </button>
+          }
+        />
+        <PopoverContent align="start" sideOffset={8} className="flex flex-col p-4 w-64">
+          <PopoverHeader>
+            <PopoverTitle className="text-lg font-bold">씨앗 순장</PopoverTitle>
+          </PopoverHeader>
+
+          <div className="flex items-center justify-center py-3">
+            <Image
+              src="/img/씨앗ai.png"
+              alt="씨앗ai"
+              width={120}
+              height={120}
+              className="rounded-full"
+            />
+          </div>
+
+          <ul className="text-sm space-y-1 text-foreground/80">
+            <li>• 이름: 씨앗 (C-at)</li>
+            <li>• 직분: 순장</li>
+            <li>• MBTI: ENFP</li>
+          </ul>
+
+          <div className="mt-3 pt-3 border-t border-border/50">
+            <p className="text-xs text-foreground/60">캠퍼스 현장에서 함께 자라가는 동역자예요.</p>
+          </div>
+        </PopoverContent>
+      </Popover>
+      <h1 className="text-lg font-semibold tracking-tight text-foreground/90">씨앗 순장</h1>
+    </div>
+  );
+}
diff --git a/lib/env.ts b/src/lib/env.ts
similarity index 81%
rename from lib/env.ts
rename to src/lib/env.ts
index e2d07b2..bfc2d34 100644
--- a/lib/env.ts
+++ b/src/lib/env.ts
@@ -10,10 +10,7 @@ export function getServerEnv(): ServerEnv {
   const apiKey = process.env.DIFY_API_KEY;
 
   if (!baseUrl || !apiKey) {
-    const missing = [
-      !baseUrl ? "DIFY_BASE_URL" : null,
-      !apiKey ? "DIFY_API_KEY" : null,
-    ]
+    const missing = [!baseUrl ? "DIFY_BASE_URL" : null, !apiKey ? "DIFY_API_KEY" : null]
       .filter(Boolean)
       .join(", ");
     throw new Error(`Missing required server env: ${missing}`);
diff --git a/lib/id.ts b/src/lib/id.ts
similarity index 100%
rename from lib/id.ts
rename to src/lib/id.ts
diff --git a/lib/utils.ts b/src/lib/utils.ts
similarity index 100%
rename from lib/utils.ts
rename to src/lib/utils.ts
diff --git a/tsconfig.json b/tsconfig.json
index 3a13f90..cf9c65d 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -19,7 +19,7 @@
       }
     ],
     "paths": {
-      "@/*": ["./*"]
+      "@/*": ["./src/*"]
     }
   },
   "include": [