diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index cd25f02..4ce1ef0 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -47,6 +47,9 @@ jobs:
         with:
           validate-wrappers: true
 
+      - name: Write google-services.json
+        run: echo "${{ secrets.GOOGLE_SERVICES_JSON }}" | base64 -d > app/google-services.json
+
       - name: Run ${{ matrix.task }}
         run: ./gradlew ${{ matrix.task }} --stacktrace
 
diff --git a/.gitignore b/.gitignore
index 047bbc3..9c31517 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,6 +3,8 @@
 .idea/
 .kotlin/
 build/
+bin/
 local.properties
 */build/
 .worktree-*
+app/google-services.json
diff --git a/README.md b/README.md
index 39952bd..9e5e19f 100644
--- a/README.md
+++ b/README.md
@@ -69,23 +69,31 @@ API 키 등 비밀 값이 필요한 경우에도 `local.properties`에 두고 
 
 ## 프로젝트 구조
 
-멀티모듈 구조로 구성한다. 세부 모듈 구성은 진행 상황에 따라 확정한다.
+멀티모듈 구조로 구성한다. 새 feature나 데이터 소스를 추가할 때도 아래 구조와 의존성 방향을 따른다.
 
 ```
 GAMSS-Android/
-├─ app/           # 앱 진입점, DI 구성, 네비게이션 호스트 (예정)
-├─ core/          # 공통 유틸, 디자인 시스템, 네트워크/DB 기반 (예정)
-├─ feature/       # 화면 단위 기능 모듈 (예정)
-├─ data/          # 데이터 소스, 저장소 구현 (예정)
-└─ gradle/        # 버전 카탈로그, wrapper
+├─ app/                # 앱 진입점, Hilt DI 그래프 조립, Navigation3 호스트
+├─ domain/             # UseCase, Repository 인터페이스, 도메인 모델 (순수 Kotlin/JVM, Android 의존성 없음)
+├─ data/                # Repository 구현체, 원격(remote)·로컬 데이터 소스, DI 모듈(di)
+├─ core/
+│   ├─ common/         # 모듈 간 공유되는 순수 유틸 (AppResult 등)
+│   └─ ui/             # 공용 Compose UI 컴포넌트 (GamssBottomBar 등)
+├─ feature/
+│   └─ home/           # 화면 단위 기능 모듈. 화면별로 하나씩 추가한다
+└─ gradle/             # 버전 카탈로그, wrapper
 ```
 
-| 모듈 | 역할 |
-| --- | --- |
-| `app` | 앱 진입점, DI 그래프 구성, 네비게이션 호스트 |
-| `core` | 여러 기능에서 공유하는 공통 코드 (UI 컴포넌트, 네트워크·DB 기반, 유틸) |
-| `feature` | 화면 단위 기능 모듈 (기능별로 분리) |
-| `data` | 데이터 소스 및 저장소(Repository) 구현 |
+| 모듈 | 역할 | 의존하는 모듈 |
+| --- | --- | --- |
+| `app` | 앱 진입점, Hilt DI 그래프 조립, Navigation3 호스트 | `domain`, `data`, `core:common`, `core:ui`, `feature:*` |
+| `domain` | UseCase, Repository 인터페이스, 도메인 모델 | 없음 |
+| `data` | Repository 구현, 원격/로컬 데이터 소스, Hilt DI 모듈 | `domain`, `core:common` |
+| `core:common` | 여러 모듈이 공유하는 순수 유틸 | 없음 |
+| `core:ui` | 공용 Compose UI 컴포넌트 | 없음 |
+| `feature:*` | 화면 단위 기능 모듈 (기능별로 분리) | `core:ui` (필요 시 `domain`) |
+
+**의존성 규칙**: 안쪽 레이어(`domain`)는 바깥쪽 어떤 모듈도 참조하지 않는다. `data`, `feature`, `app`은 `domain`이 정의한 인터페이스(Repository, UseCase)에 의존하고, 구현은 바깥쪽(`data`)에 둔다. `app`은 조립부이므로 예외적으로 전체 모듈을 참조한다.
 
 ## 기술 스택
 
diff --git a/app/build.gradle.kts b/app/build.gradle.kts
index 5ff2fda..11e7cec 100644
--- a/app/build.gradle.kts
+++ b/app/build.gradle.kts
@@ -1,9 +1,13 @@
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+
 plugins {
     alias(libs.plugins.androidApplication)
     alias(libs.plugins.composeCompiler)
     alias(libs.plugins.kotlinSerialization)
     alias(libs.plugins.ksp)
     alias(libs.plugins.hilt)
+    alias(libs.plugins.googleServices)
+    alias(libs.plugins.firebaseCrashlytics)
 }
 
 android {
@@ -36,22 +40,29 @@ android {
 
 kotlin {
     compilerOptions {
-        jvmTarget = org.jetbrains.kotlin.gradle.dsl.JvmTarget.JVM_17
+        jvmTarget = JvmTarget.JVM_17
     }
 }
 
 dependencies {
-    implementation(projects.core)
+
     implementation(projects.domain)
     implementation(projects.data)
+    implementation(projects.core.common)
+    implementation(projects.core.ui)
+    implementation(projects.feature.home)
+    implementation(projects.feature.chat)
+    implementation(projects.feature.calendar)
 
     implementation(platform(libs.compose.bom))
     implementation(libs.compose.ui)
     implementation(libs.compose.ui.graphics)
     implementation(libs.compose.ui.tooling.preview)
     implementation(libs.compose.material3)
+    implementation(libs.compose.material.icons.core)
     implementation(libs.androidx.activity.compose)
     implementation(libs.androidx.lifecycle.runtime.ktx)
+    implementation(libs.androidx.lifecycle.viewmodel.navigation3)
 
     implementation(libs.navigation3.runtime)
     implementation(libs.navigation3.ui)
@@ -59,5 +70,9 @@ dependencies {
     implementation(libs.hilt.android)
     ksp(libs.hilt.compiler)
 
+    implementation(platform(libs.firebase.bom))
+    implementation(libs.firebase.crashlytics)
+    implementation(libs.firebase.analytics)
+
     debugImplementation(libs.compose.ui.tooling)
 }
diff --git a/app/src/main/kotlin/com/gamss/android/app/MainActivity.kt b/app/src/main/kotlin/com/gamss/android/app/MainActivity.kt
index 796fce1..523d975 100644
--- a/app/src/main/kotlin/com/gamss/android/app/MainActivity.kt
+++ b/app/src/main/kotlin/com/gamss/android/app/MainActivity.kt
@@ -4,7 +4,7 @@ import android.os.Bundle
 import androidx.activity.ComponentActivity
 import androidx.activity.compose.setContent
 import androidx.activity.enableEdgeToEdge
-import com.gamss.android.app.navigation.AppNavHost
+import com.gamss.android.app.navigation.GamssNavHost
 import com.gamss.android.app.ui.theme.GamssTheme
 import dagger.hilt.android.AndroidEntryPoint
 
@@ -15,7 +15,7 @@ class MainActivity : ComponentActivity() {
         enableEdgeToEdge()
         setContent {
             GamssTheme {
-                AppNavHost()
+                GamssNavHost()
             }
         }
     }
diff --git a/app/src/main/kotlin/com/gamss/android/app/navigation/AppNavHost.kt b/app/src/main/kotlin/com/gamss/android/app/navigation/AppNavHost.kt
deleted file mode 100644
index 20f28cf..0000000
--- a/app/src/main/kotlin/com/gamss/android/app/navigation/AppNavHost.kt
+++ /dev/null
@@ -1,20 +0,0 @@
-package com.gamss.android.app.navigation
-
-import androidx.compose.runtime.Composable
-import androidx.navigation3.runtime.entryProvider
-import androidx.navigation3.runtime.rememberNavBackStack
-import androidx.navigation3.ui.NavDisplay
-import com.gamss.android.app.ui.HomeScreen
-
-@Composable
-fun AppNavHost() {
-    val backStack = rememberNavBackStack(HomeKey)
-
-    NavDisplay(
-        backStack = backStack,
-        onBack = { backStack.removeLastOrNull() },
-        entryProvider = entryProvider {
-            entry<HomeKey> { HomeScreen() }
-        },
-    )
-}
diff --git a/app/src/main/kotlin/com/gamss/android/app/navigation/GamssNavHost.kt b/app/src/main/kotlin/com/gamss/android/app/navigation/GamssNavHost.kt
new file mode 100644
index 0000000..fa5165c
--- /dev/null
+++ b/app/src/main/kotlin/com/gamss/android/app/navigation/GamssNavHost.kt
@@ -0,0 +1,53 @@
+package com.gamss.android.app.navigation
+
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material3.Scaffold
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.remember
+import androidx.compose.ui.Modifier
+import androidx.navigation3.runtime.entryProvider
+import androidx.navigation3.ui.NavDisplay
+import com.gamss.android.core.ui.GamssBottomBar
+import com.gamss.android.feature.calendar.CalendarScreen
+import com.gamss.android.feature.calendar.navigation.CalendarKey
+import com.gamss.android.feature.chat.ChattingListScreen
+import com.gamss.android.feature.chat.navigation.ChatKey
+import com.gamss.android.feature.home.HomeScreen
+import com.gamss.android.feature.home.navigation.HomeKey
+
+@Composable
+fun GamssNavHost() {
+    val navigationState = rememberNavigationState(
+        startKey = HomeKey,
+        topLevelKeys = topLevelDestinationKeys,
+    )
+    val navigator = remember(navigationState) { Navigator(navigationState) }
+
+    Scaffold(
+        bottomBar = {
+            if (navigationState.currentKey == navigationState.currentTopLevelKey) {
+                GamssBottomBar(
+                    items = topLevelBottomBarItems,
+                    selectedValue = navigationState.currentTopLevelKey,
+                    onItemClick = navigator::navigate,
+                )
+            }
+        },
+    ) { innerPadding ->
+        NavDisplay(
+            modifier = Modifier.padding(innerPadding),
+            entries = navigationState.toEntries(
+                entryProvider = entryProvider {
+                    entry<HomeKey> { HomeScreen() }
+                    entry<ChatKey> { ChattingListScreen() }
+                    entry<CalendarKey> { CalendarScreen() }
+                },
+            ),
+            onBack = {
+                if (navigationState.canGoBack) {
+                    navigator.goBack()
+                }
+            },
+        )
+    }
+}
diff --git a/app/src/main/kotlin/com/gamss/android/app/navigation/NavigationState.kt b/app/src/main/kotlin/com/gamss/android/app/navigation/NavigationState.kt
new file mode 100644
index 0000000..43b0e53
--- /dev/null
+++ b/app/src/main/kotlin/com/gamss/android/app/navigation/NavigationState.kt
@@ -0,0 +1,90 @@
+package com.gamss.android.app.navigation
+
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.derivedStateOf
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.remember
+import androidx.lifecycle.viewmodel.navigation3.rememberViewModelStoreNavEntryDecorator
+import androidx.navigation3.runtime.NavBackStack
+import androidx.navigation3.runtime.NavEntry
+import androidx.navigation3.runtime.NavKey
+import androidx.navigation3.runtime.rememberDecoratedNavEntries
+import androidx.navigation3.runtime.rememberNavBackStack
+import androidx.navigation3.runtime.rememberSaveableStateHolderNavEntryDecorator
+
+/**
+ * GAMSS 메인 탭 네비게이션 상태를 생성한다.
+ *
+ * Navigation3의 back stack은 rememberSaveable 기반으로 동작하므로 화면 회전이나
+ * 프로세스 재생성 이후에도 복원 가능한 key를 사용해야 한다.
+ *
+ * @param startKey 앱의 메인 영역에서 처음 보여줄 최상위 key
+ * @param topLevelKeys bottom bar에 연결되는 최상위 key 목록
+ */
+@Composable
+fun rememberNavigationState(
+    startKey: NavKey,
+    topLevelKeys: Set<NavKey>,
+): NavigationState {
+    val topLevelStack = rememberNavBackStack(startKey)
+    val subStacks = topLevelKeys.associateWith { key -> rememberNavBackStack(key) }
+
+    return remember(startKey, topLevelKeys) {
+        NavigationState(
+            startKey = startKey,
+            topLevelStack = topLevelStack,
+            subStacks = subStacks,
+        )
+    }
+}
+
+/**
+ * bottom bar 기반 화면 전환을 위한 상태 홀더.
+ *
+ * topLevelStack은 사용자가 방문한 탭 순서를 저장하고, subStacks는 각 탭 내부의 상세 화면
+ * stack을 따로 저장한다. 탭을 전환해도 탭의 상세 화면 흐름을 유지할 수 있다.
+ */
+class NavigationState(
+    val startKey: NavKey,
+    val topLevelStack: NavBackStack<NavKey>,
+    val subStacks: Map<NavKey, NavBackStack<NavKey>>,
+) {
+    val currentTopLevelKey: NavKey by derivedStateOf { topLevelStack.last() }
+
+    val topLevelKeys
+        get() = subStacks.keys
+
+    val currentSubStack: NavBackStack<NavKey>
+        get() = subStacks[currentTopLevelKey]
+            ?: error("현재 탭($currentTopLevelKey)에 해당하는 back stack이 없습니다.")
+
+    val currentKey: NavKey by derivedStateOf { currentSubStack.last() }
+
+    val canGoBack: Boolean by derivedStateOf { currentKey != startKey }
+}
+
+/**
+ * NavigationState를 NavDisplay에서 사용할 entry 목록으로 변환한다.
+ *
+ * 각 탭의 sub stack에 saveable state와 ViewModelStore decorator를 붙여서, 탭 전환 중에도
+ * 화면 상태와 ViewModel 생명주기가 탭별 back stack에 맞게 유지되도록 한다.
+ */
+@Composable
+fun NavigationState.toEntries(
+    entryProvider: (NavKey) -> NavEntry<NavKey>,
+): List<NavEntry<NavKey>> {
+    val decoratedEntries = subStacks.mapValues { (_, stack) ->
+        val decorators = listOf(
+            rememberSaveableStateHolderNavEntryDecorator<NavKey>(),
+            rememberViewModelStoreNavEntryDecorator<NavKey>(),
+        )
+        rememberDecoratedNavEntries(
+            backStack = stack,
+            entryDecorators = decorators,
+            entryProvider = entryProvider,
+        )
+    }
+
+    return topLevelStack
+        .flatMap { decoratedEntries[it] ?: emptyList() }
+}
diff --git a/app/src/main/kotlin/com/gamss/android/app/navigation/Navigator.kt b/app/src/main/kotlin/com/gamss/android/app/navigation/Navigator.kt
new file mode 100644
index 0000000..b3fd1e7
--- /dev/null
+++ b/app/src/main/kotlin/com/gamss/android/app/navigation/Navigator.kt
@@ -0,0 +1,75 @@
+package com.gamss.android.app.navigation
+
+import androidx.navigation3.runtime.NavKey
+
+/**
+ * NavigationState를 변경하는 앱 전용 navigator.
+ *
+ * GAMSS의 bottom bar 정책을 한 곳에 모아둔다.
+ * - 현재 탭을 다시 선택하면 해당 탭의 root 화면으로 이동
+ * - 다른 탭을 선택하면 방문한 탭 순서를 topLevelStack에 기록
+ * - 상세 화면은 현재 탭의 sub stack에 쌓되, 같은 key가 이미 있으면 마지막으로 이동
+ */
+class Navigator(val state: NavigationState) {
+
+    /**
+     * 지정한 key로 이동한다.
+     * top-level key인지, 현재 탭인지, 상세 key인지에 따라 stack 갱신 규칙이 달라진다.
+     */
+    fun navigate(key: NavKey) {
+        when (key) {
+            state.currentTopLevelKey -> clearSubStack()
+            in state.topLevelKeys -> goToTopLevel(key)
+            else -> goToKey(key)
+        }
+    }
+
+    /**
+     * 현재 위치에서 뒤로 이동한다.
+     *
+     * 현재 탭의 root 화면에서는 이전에 방문한 탭으로 돌아가고, 상세 화면에서는 현재 탭의
+     * sub stack에서 한 단계 pop한다.
+     */
+    fun goBack() {
+        when (state.currentKey) {
+            state.startKey -> Unit
+            state.currentTopLevelKey -> {
+                state.topLevelStack.removeLastOrNull()
+            }
+            else -> state.currentSubStack.removeLastOrNull()
+        }
+    }
+
+    /**
+     * 현재 탭의 상세 화면으로 이동한다.
+     */
+    private fun goToKey(key: NavKey) {
+        state.currentSubStack.apply {
+            remove(key)
+            add(key)
+        }
+    }
+
+    /**
+     * 다른 top-level 탭으로 이동한다.
+     */
+    private fun goToTopLevel(key: NavKey) {
+        state.topLevelStack.apply {
+            if (key == state.startKey) {
+                clear()
+            } else {
+                remove(key)
+            }
+            add(key)
+        }
+    }
+
+    /**
+     * 현재 탭을 다시 선택했을 때 root 화면만 남긴다.
+     */
+    private fun clearSubStack() {
+        state.currentSubStack.run {
+            if (size > 1) subList(1, size).clear()
+        }
+    }
+}
diff --git a/app/src/main/kotlin/com/gamss/android/app/navigation/TopLevelDestination.kt b/app/src/main/kotlin/com/gamss/android/app/navigation/TopLevelDestination.kt
new file mode 100644
index 0000000..03c4574
--- /dev/null
+++ b/app/src/main/kotlin/com/gamss/android/app/navigation/TopLevelDestination.kt
@@ -0,0 +1,39 @@
+package com.gamss.android.app.navigation
+
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.DateRange
+import androidx.compose.material.icons.filled.Email
+import androidx.compose.material.icons.filled.Home
+import androidx.compose.ui.graphics.vector.ImageVector
+import androidx.navigation3.runtime.NavKey
+import com.gamss.android.core.ui.GamssBottomBarItem
+import com.gamss.android.feature.calendar.navigation.CalendarKey
+import com.gamss.android.feature.chat.navigation.ChatKey
+import com.gamss.android.feature.home.navigation.HomeKey
+
+/**
+ * bottom bar에 표시되는 최상위 탭 목록.
+ *
+ * 새로운 feature 모듈이 하단 탭으로 추가될 때마다 이 목록에 항목을 더한다.
+ */
+data class TopLevelDestination(
+    val key: NavKey,
+    val icon: ImageVector,
+    val label: String,
+)
+
+val topLevelDestinations = listOf(
+    TopLevelDestination(key = HomeKey, icon = Icons.Filled.Home, label = "홈"),
+    TopLevelDestination(key = ChatKey, icon = Icons.Filled.Email, label = "대화"),
+    TopLevelDestination(key = CalendarKey, icon = Icons.Filled.DateRange, label = "달력"),
+)
+
+val topLevelDestinationKeys = topLevelDestinations.map { it.key }.toSet()
+
+val topLevelBottomBarItems: List<GamssBottomBarItem<NavKey>> = topLevelDestinations.map { destination ->
+    GamssBottomBarItem(
+        value = destination.key,
+        icon = destination.icon,
+        label = destination.label,
+    )
+}
diff --git a/build.gradle.kts b/build.gradle.kts
index 3e4ffb6..7de44a7 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -3,9 +3,12 @@ plugins {
     alias(libs.plugins.androidLibrary) apply false
     alias(libs.plugins.kotlinJvm) apply false
     alias(libs.plugins.composeCompiler) apply false
+    alias(libs.plugins.kotlinSerialization) apply false
     alias(libs.plugins.ksp) apply false
     alias(libs.plugins.hilt) apply false
     alias(libs.plugins.detekt)
+    alias(libs.plugins.googleServices) apply false
+    alias(libs.plugins.firebaseCrashlytics) apply false
 }
 
 val detektPluginId = libs.plugins.detekt.get().pluginId
diff --git a/core/build.gradle.kts b/core/common/build.gradle.kts
similarity index 98%
rename from core/build.gradle.kts
rename to core/common/build.gradle.kts
index a3b9cb9..bea50c5 100644
--- a/core/build.gradle.kts
+++ b/core/common/build.gradle.kts
@@ -8,4 +8,4 @@ kotlin {
 
 dependencies {
     testImplementation(libs.junit)
-}
+}
\ No newline at end of file
diff --git a/core/src/main/kotlin/com/gamss/android/core/AppResult.kt b/core/common/src/main/java/com/gamss/android/core/common/AppResult.kt
similarity index 94%
rename from core/src/main/kotlin/com/gamss/android/core/AppResult.kt
rename to core/common/src/main/java/com/gamss/android/core/common/AppResult.kt
index 5269fd1..e3b4c39 100644
--- a/core/src/main/kotlin/com/gamss/android/core/AppResult.kt
+++ b/core/common/src/main/java/com/gamss/android/core/common/AppResult.kt
@@ -1,4 +1,4 @@
-package com.gamss.android.core
+package com.gamss.android.core.common
 
 sealed interface AppResult<out T> {
     data class Success<T>(val data: T) : AppResult<T>
diff --git a/core/src/test/kotlin/com/gamss/android/core/AppResultTest.kt b/core/src/test/kotlin/com/gamss/android/core/AppResultTest.kt
deleted file mode 100644
index 2b679ea..0000000
--- a/core/src/test/kotlin/com/gamss/android/core/AppResultTest.kt
+++ /dev/null
@@ -1,34 +0,0 @@
-package com.gamss.android.core
-
-import org.junit.Assert.assertEquals
-import org.junit.Assert.assertTrue
-import org.junit.Test
-
-class AppResultTest {
-
-    @Test
-    fun of_capturesSuccess() {
-        val result = AppResult.of { 42 }
-        assertTrue(result is AppResult.Success)
-        assertEquals(42, result.getOrNull())
-    }
-
-    @Test
-    fun of_capturesFailure() {
-        val result = AppResult.of { error("boom") }
-        assertTrue(result is AppResult.Failure)
-    }
-
-    @Test
-    fun map_transformsSuccess() {
-        val result = AppResult.Success(2).map { it * 3 }
-        assertEquals(6, result.getOrNull())
-    }
-
-    @Test
-    fun map_passesThroughFailure() {
-        val failure: AppResult<Int> = AppResult.Failure(IllegalStateException())
-        val mapped = failure.map { it * 3 }
-        assertTrue(mapped is AppResult.Failure)
-    }
-}
diff --git a/core/ui/build.gradle.kts b/core/ui/build.gradle.kts
new file mode 100644
index 0000000..9fc6480
--- /dev/null
+++ b/core/ui/build.gradle.kts
@@ -0,0 +1,47 @@
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+
+plugins {
+    alias(libs.plugins.androidLibrary)
+    alias(libs.plugins.composeCompiler)
+}
+
+android {
+    namespace = "com.gamss.android.core.ui"
+    compileSdk = libs.versions.android.compileSdk.get().toInt()
+
+    defaultConfig {
+        minSdk = libs.versions.android.minSdk.get().toInt()
+
+        testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
+    }
+    buildFeatures {
+        compose = true
+    }
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_17
+        targetCompatibility = JavaVersion.VERSION_17
+    }
+
+}
+
+kotlin {
+    compilerOptions {
+        jvmTarget = JvmTarget.JVM_17
+    }
+}
+
+dependencies {
+    implementation(libs.androidx.core.ktx)
+
+    // compose
+    implementation(platform(libs.compose.bom))
+    implementation(libs.compose.ui)
+    implementation(libs.compose.ui.graphics)
+    implementation(libs.compose.ui.tooling.preview)
+    implementation(libs.compose.material3)
+    implementation(libs.compose.material.icons.core)
+    debugImplementation(libs.compose.ui.tooling)
+
+    // test
+    testImplementation(libs.junit)
+}
\ No newline at end of file
diff --git a/core/ui/src/main/kotlin/com/gamss/android/core/ui/GamssBottomBar.kt b/core/ui/src/main/kotlin/com/gamss/android/core/ui/GamssBottomBar.kt
new file mode 100644
index 0000000..f97a1b8
--- /dev/null
+++ b/core/ui/src/main/kotlin/com/gamss/android/core/ui/GamssBottomBar.kt
@@ -0,0 +1,25 @@
+package com.gamss.android.core.ui
+
+import androidx.compose.material3.Icon
+import androidx.compose.material3.NavigationBar
+import androidx.compose.material3.NavigationBarItem
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+
+@Composable
+fun <T> GamssBottomBar(
+    items: List<GamssBottomBarItem<T>>,
+    selectedValue: T,
+    onItemClick: (T) -> Unit,
+) {
+    NavigationBar {
+        items.forEach { item ->
+            NavigationBarItem(
+                selected = item.value == selectedValue,
+                onClick = { onItemClick(item.value) },
+                icon = { Icon(imageVector = item.icon, contentDescription = item.label) },
+                label = { Text(text = item.label) },
+            )
+        }
+    }
+}
diff --git a/core/ui/src/main/kotlin/com/gamss/android/core/ui/GamssBottomBarItem.kt b/core/ui/src/main/kotlin/com/gamss/android/core/ui/GamssBottomBarItem.kt
new file mode 100644
index 0000000..3a740da
--- /dev/null
+++ b/core/ui/src/main/kotlin/com/gamss/android/core/ui/GamssBottomBarItem.kt
@@ -0,0 +1,9 @@
+package com.gamss.android.core.ui
+
+import androidx.compose.ui.graphics.vector.ImageVector
+
+data class GamssBottomBarItem<T>(
+    val value: T,
+    val icon: ImageVector,
+    val label: String,
+)
diff --git a/data/build.gradle.kts b/data/build.gradle.kts
index c40d677..eb236a3 100644
--- a/data/build.gradle.kts
+++ b/data/build.gradle.kts
@@ -1,5 +1,8 @@
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+
 plugins {
     alias(libs.plugins.androidLibrary)
+    alias(libs.plugins.ksp)
 }
 
 android {
@@ -8,21 +11,35 @@ android {
 
     defaultConfig {
         minSdk = libs.versions.android.minSdk.get().toInt()
-    }
 
+        testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
+    }
+    buildFeatures {
+        buildConfig = true
+    }
     compileOptions {
         sourceCompatibility = JavaVersion.VERSION_17
         targetCompatibility = JavaVersion.VERSION_17
     }
+
 }
 
 kotlin {
     compilerOptions {
-        jvmTarget = org.jetbrains.kotlin.gradle.dsl.JvmTarget.JVM_17
+        jvmTarget = JvmTarget.JVM_17
     }
 }
 
 dependencies {
-    api(projects.domain)
-    implementation(projects.core)
-}
+    implementation(projects.domain)
+    implementation(projects.core.common)
+
+    implementation(libs.hilt.android)
+    ksp(libs.hilt.compiler)
+
+    implementation(libs.retrofit)
+    implementation(libs.retrofit.converter.kotlinx.serialization)
+    implementation(libs.okhttp)
+    implementation(libs.okhttp.logging.interceptor)
+    implementation(libs.kotlinx.serialization.json)
+}
\ No newline at end of file
diff --git a/data/src/main/java/com/gamss/android/data/di/NetworkModule.kt b/data/src/main/java/com/gamss/android/data/di/NetworkModule.kt
new file mode 100644
index 0000000..ee6a51a
--- /dev/null
+++ b/data/src/main/java/com/gamss/android/data/di/NetworkModule.kt
@@ -0,0 +1,61 @@
+package com.gamss.android.data.di
+
+import com.gamss.android.data.BuildConfig
+import com.gamss.android.data.remote.auth.AuthService
+import dagger.Module
+import dagger.Provides
+import dagger.hilt.InstallIn
+import dagger.hilt.components.SingletonComponent
+import kotlinx.serialization.json.Json
+import okhttp3.MediaType.Companion.toMediaType
+import okhttp3.OkHttpClient
+import okhttp3.logging.HttpLoggingInterceptor
+import retrofit2.Retrofit
+import retrofit2.converter.kotlinx.serialization.asConverterFactory
+import javax.inject.Singleton
+
+@Module
+@InstallIn(SingletonComponent::class)
+object NetworkModule {
+
+    @Provides
+    @Singleton
+    fun provideJson(): Json = Json {
+        ignoreUnknownKeys = true
+        coerceInputValues = true
+    }
+
+    @Provides
+    @Singleton
+    fun provideOkHttpClient(): OkHttpClient {
+        val loggingInterceptor = HttpLoggingInterceptor().apply {
+            level = if (BuildConfig.DEBUG) {
+                HttpLoggingInterceptor.Level.BODY
+            } else {
+                HttpLoggingInterceptor.Level.NONE
+            }
+        }
+        return OkHttpClient.Builder()
+            .addInterceptor(loggingInterceptor)
+            .build()
+    }
+
+    @Provides
+    @Singleton
+    fun provideRetrofit(
+        okHttpClient: OkHttpClient,
+        json: Json
+    ): Retrofit {
+        return Retrofit.Builder()
+            // mock 주소. 실제 백엔드 API 주소가 확정되면 교체한다.
+            .baseUrl("https://api.gamss.example.com/")
+            .client(okHttpClient)
+            .addConverterFactory(json.asConverterFactory("application/json".toMediaType()))
+            .build()
+    }
+
+    @Provides
+    @Singleton
+    fun provideAuthService(retrofit: Retrofit): AuthService =
+        retrofit.create(AuthService::class.java)
+}
diff --git a/data/src/main/java/com/gamss/android/data/di/RepositoryModule.kt b/data/src/main/java/com/gamss/android/data/di/RepositoryModule.kt
new file mode 100644
index 0000000..98d28df
--- /dev/null
+++ b/data/src/main/java/com/gamss/android/data/di/RepositoryModule.kt
@@ -0,0 +1,18 @@
+package com.gamss.android.data.di
+
+import com.gamss.android.data.repository.AuthRepositoryImpl
+import com.gamss.android.domain.repository.AuthRepository
+import dagger.Binds
+import dagger.Module
+import dagger.hilt.InstallIn
+import dagger.hilt.components.SingletonComponent
+
+@Module
+@InstallIn(SingletonComponent::class)
+internal abstract class RepositoryModule {
+
+    @Binds
+    abstract fun bindAuthRepository(
+        authRepositoryImpl: AuthRepositoryImpl
+    ): AuthRepository
+}
diff --git a/data/src/main/java/com/gamss/android/data/remote/auth/AuthService.kt b/data/src/main/java/com/gamss/android/data/remote/auth/AuthService.kt
new file mode 100644
index 0000000..6c5e8d0
--- /dev/null
+++ b/data/src/main/java/com/gamss/android/data/remote/auth/AuthService.kt
@@ -0,0 +1,12 @@
+package com.gamss.android.data.remote.auth
+
+import com.gamss.android.data.remote.auth.model.request.LoginRequest
+import com.gamss.android.data.remote.auth.model.response.LoginResponse
+import retrofit2.http.Body
+import retrofit2.http.POST
+
+interface AuthService {
+
+    @POST("/login")
+    suspend fun login(@Body request: LoginRequest): LoginResponse
+}
diff --git a/data/src/main/java/com/gamss/android/data/remote/auth/model/request/LoginRequest.kt b/data/src/main/java/com/gamss/android/data/remote/auth/model/request/LoginRequest.kt
new file mode 100644
index 0000000..2e3d74e
--- /dev/null
+++ b/data/src/main/java/com/gamss/android/data/remote/auth/model/request/LoginRequest.kt
@@ -0,0 +1,10 @@
+package com.gamss.android.data.remote.auth.model.request
+
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class LoginRequest(
+    @SerialName("userId")
+    val userId: String,
+)
diff --git a/data/src/main/java/com/gamss/android/data/remote/auth/model/response/LoginResponse.kt b/data/src/main/java/com/gamss/android/data/remote/auth/model/response/LoginResponse.kt
new file mode 100644
index 0000000..2b9964f
--- /dev/null
+++ b/data/src/main/java/com/gamss/android/data/remote/auth/model/response/LoginResponse.kt
@@ -0,0 +1,18 @@
+package com.gamss.android.data.remote.auth.model.response
+
+import com.gamss.android.domain.model.AuthResponse
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class LoginResponse(
+    @SerialName("accessToken")
+    val accessToken: String,
+    @SerialName("refreshToken")
+    val refreshToken: String,
+) {
+    fun toDomain() = AuthResponse(
+        accessToken = accessToken,
+        refreshToken = refreshToken
+    )
+}
diff --git a/data/src/main/java/com/gamss/android/data/repository/AuthRepositoryImpl.kt b/data/src/main/java/com/gamss/android/data/repository/AuthRepositoryImpl.kt
new file mode 100644
index 0000000..81edc11
--- /dev/null
+++ b/data/src/main/java/com/gamss/android/data/repository/AuthRepositoryImpl.kt
@@ -0,0 +1,16 @@
+package com.gamss.android.data.repository
+
+import com.gamss.android.core.common.AppResult
+import com.gamss.android.data.remote.auth.AuthService
+import com.gamss.android.data.remote.auth.model.request.LoginRequest
+import com.gamss.android.domain.model.AuthResponse
+import com.gamss.android.domain.repository.AuthRepository
+import javax.inject.Inject
+
+class AuthRepositoryImpl @Inject constructor(
+    private val authService: AuthService,
+) : AuthRepository {
+
+    override suspend fun login(userId: String): AppResult<AuthResponse> =
+        AppResult.of { authService.login(LoginRequest(userId = userId)).toDomain() }
+}
diff --git a/domain/build.gradle.kts b/domain/build.gradle.kts
index 58fe427..c2a6b24 100644
--- a/domain/build.gradle.kts
+++ b/domain/build.gradle.kts
@@ -7,7 +7,7 @@ kotlin {
 }
 
 dependencies {
-    api(projects.core)
+    implementation(projects.core.common)
 
     testImplementation(libs.junit)
 }
diff --git a/domain/src/main/kotlin/com/gamss/android/domain/model/AuthResponse.kt b/domain/src/main/kotlin/com/gamss/android/domain/model/AuthResponse.kt
new file mode 100644
index 0000000..c575b0c
--- /dev/null
+++ b/domain/src/main/kotlin/com/gamss/android/domain/model/AuthResponse.kt
@@ -0,0 +1,6 @@
+package com.gamss.android.domain.model
+
+data class AuthResponse(
+    val accessToken: String? = null,
+    val refreshToken: String? = null,
+)
diff --git a/domain/src/main/kotlin/com/gamss/android/domain/repository/AuthRepository.kt b/domain/src/main/kotlin/com/gamss/android/domain/repository/AuthRepository.kt
new file mode 100644
index 0000000..9008a08
--- /dev/null
+++ b/domain/src/main/kotlin/com/gamss/android/domain/repository/AuthRepository.kt
@@ -0,0 +1,8 @@
+package com.gamss.android.domain.repository
+
+import com.gamss.android.core.common.AppResult
+import com.gamss.android.domain.model.AuthResponse
+
+interface AuthRepository {
+    suspend fun login(userId: String): AppResult<AuthResponse>
+}
diff --git a/domain/src/main/kotlin/com/gamss/android/domain/UseCase.kt b/domain/src/main/kotlin/com/gamss/android/domain/usecase/UseCase.kt
similarity index 79%
rename from domain/src/main/kotlin/com/gamss/android/domain/UseCase.kt
rename to domain/src/main/kotlin/com/gamss/android/domain/usecase/UseCase.kt
index dc41447..abbb063 100644
--- a/domain/src/main/kotlin/com/gamss/android/domain/UseCase.kt
+++ b/domain/src/main/kotlin/com/gamss/android/domain/usecase/UseCase.kt
@@ -1,4 +1,4 @@
-package com.gamss.android.domain
+package com.gamss.android.domain.usecase
 
 interface UseCase<in P, out R> {
     suspend operator fun invoke(params: P): R
diff --git a/feature/calendar/build.gradle.kts b/feature/calendar/build.gradle.kts
new file mode 100644
index 0000000..e19472b
--- /dev/null
+++ b/feature/calendar/build.gradle.kts
@@ -0,0 +1,62 @@
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+
+plugins {
+    alias(libs.plugins.androidLibrary)
+    alias(libs.plugins.composeCompiler)
+    alias(libs.plugins.kotlinSerialization)
+    alias(libs.plugins.ksp)
+}
+
+android {
+    namespace = "com.gamss.android.feature.calendar"
+    compileSdk = libs.versions.android.compileSdk.get().toInt()
+
+    defaultConfig {
+        minSdk = libs.versions.android.minSdk.get().toInt()
+
+        testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
+    }
+    buildFeatures {
+        compose = true
+    }
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_17
+        targetCompatibility = JavaVersion.VERSION_17
+    }
+
+}
+
+kotlin {
+    compilerOptions {
+        jvmTarget = JvmTarget.JVM_17
+    }
+}
+
+dependencies {
+    implementation(projects.core.ui)
+    implementation(libs.androidx.core.ktx)
+
+    implementation(platform(libs.compose.bom))
+    implementation(libs.compose.ui)
+    implementation(libs.compose.ui.graphics)
+    implementation(libs.compose.ui.tooling.preview)
+    implementation(libs.compose.material3)
+
+    implementation(libs.navigation3.runtime)
+    implementation(libs.kotlinx.serialization.json)
+
+    implementation(libs.androidx.lifecycle.viewmodel.ktx)
+    implementation(libs.androidx.hilt.navigation.compose)
+    implementation(libs.hilt.android)
+    ksp(libs.hilt.compiler)
+
+    implementation(libs.orbit.core)
+    implementation(libs.orbit.viewmodel)
+    implementation(libs.orbit.compose)
+
+    debugImplementation(libs.compose.ui.tooling)
+
+    testImplementation(libs.junit)
+    testImplementation(libs.orbit.test)
+    androidTestImplementation(libs.androidx.junit)
+}
\ No newline at end of file
diff --git a/feature/calendar/src/androidTest/java/com/gamss/android/feature/calendar/ExampleInstrumentedTest.kt b/feature/calendar/src/androidTest/java/com/gamss/android/feature/calendar/ExampleInstrumentedTest.kt
new file mode 100644
index 0000000..5e78716
--- /dev/null
+++ b/feature/calendar/src/androidTest/java/com/gamss/android/feature/calendar/ExampleInstrumentedTest.kt
@@ -0,0 +1,24 @@
+package com.gamss.android.feature.calendar
+
+import androidx.test.platform.app.InstrumentationRegistry
+import androidx.test.ext.junit.runners.AndroidJUnit4
+
+import org.junit.Test
+import org.junit.runner.RunWith
+
+import org.junit.Assert.*
+
+/**
+ * Instrumented test, which will execute on an Android device.
+ *
+ * See [testing documentation](http://d.android.com/tools/testing).
+ */
+@RunWith(AndroidJUnit4::class)
+class ExampleInstrumentedTest {
+    @Test
+    fun useAppContext() {
+        // Context of the app under test.
+        val appContext = InstrumentationRegistry.getInstrumentation().targetContext
+        assertEquals("com.gamss.android.feature.calendar.test", appContext.packageName)
+    }
+}
\ No newline at end of file
diff --git a/data/src/main/AndroidManifest.xml b/feature/calendar/src/main/AndroidManifest.xml
similarity index 85%
rename from data/src/main/AndroidManifest.xml
rename to feature/calendar/src/main/AndroidManifest.xml
index b2d3ea1..a5918e6 100644
--- a/data/src/main/AndroidManifest.xml
+++ b/feature/calendar/src/main/AndroidManifest.xml
@@ -1,2 +1,4 @@
 <?xml version="1.0" encoding="utf-8"?>
-<manifest xmlns:android="http://schemas.android.com/apk/res/android" />
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+
+</manifest>
\ No newline at end of file
diff --git a/app/src/main/kotlin/com/gamss/android/app/ui/HomeScreen.kt b/feature/calendar/src/main/java/com/gamss/android/feature/calendar/CalendarScreen.kt
similarity index 71%
rename from app/src/main/kotlin/com/gamss/android/app/ui/HomeScreen.kt
rename to feature/calendar/src/main/java/com/gamss/android/feature/calendar/CalendarScreen.kt
index 740a4b2..b4cc2ae 100644
--- a/app/src/main/kotlin/com/gamss/android/app/ui/HomeScreen.kt
+++ b/feature/calendar/src/main/java/com/gamss/android/feature/calendar/CalendarScreen.kt
@@ -1,4 +1,4 @@
-package com.gamss.android.app.ui
+package com.gamss.android.feature.calendar
 
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.fillMaxSize
@@ -9,9 +9,15 @@ import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.hilt.navigation.compose.hiltViewModel
+import org.orbitmvi.orbit.compose.collectSideEffect
 
 @Composable
-fun HomeScreen() {
+fun CalendarScreen(
+    viewModel: CalendarViewModel = hiltViewModel(),
+) {
+    viewModel.collectSideEffect { }
+
     Scaffold { innerPadding ->
         Box(
             modifier = Modifier
@@ -20,7 +26,7 @@ fun HomeScreen() {
             contentAlignment = Alignment.Center,
         ) {
             Text(
-                text = "GAMSS",
+                text = "달력",
                 style = MaterialTheme.typography.headlineLarge,
             )
         }
diff --git a/feature/calendar/src/main/java/com/gamss/android/feature/calendar/CalendarSideEffect.kt b/feature/calendar/src/main/java/com/gamss/android/feature/calendar/CalendarSideEffect.kt
new file mode 100644
index 0000000..104161b
--- /dev/null
+++ b/feature/calendar/src/main/java/com/gamss/android/feature/calendar/CalendarSideEffect.kt
@@ -0,0 +1,3 @@
+package com.gamss.android.feature.calendar
+
+sealed interface CalendarSideEffect
diff --git a/feature/calendar/src/main/java/com/gamss/android/feature/calendar/CalendarState.kt b/feature/calendar/src/main/java/com/gamss/android/feature/calendar/CalendarState.kt
new file mode 100644
index 0000000..5ef4ebb
--- /dev/null
+++ b/feature/calendar/src/main/java/com/gamss/android/feature/calendar/CalendarState.kt
@@ -0,0 +1,5 @@
+package com.gamss.android.feature.calendar
+
+data class CalendarState(
+    val isLoading: Boolean = false,
+)
diff --git a/feature/calendar/src/main/java/com/gamss/android/feature/calendar/CalendarViewModel.kt b/feature/calendar/src/main/java/com/gamss/android/feature/calendar/CalendarViewModel.kt
new file mode 100644
index 0000000..8516751
--- /dev/null
+++ b/feature/calendar/src/main/java/com/gamss/android/feature/calendar/CalendarViewModel.kt
@@ -0,0 +1,15 @@
+package com.gamss.android.feature.calendar
+
+import androidx.lifecycle.ViewModel
+import dagger.hilt.android.lifecycle.HiltViewModel
+import org.orbitmvi.orbit.ContainerHost
+import org.orbitmvi.orbit.viewmodel.container
+import javax.inject.Inject
+
+@HiltViewModel
+class CalendarViewModel @Inject constructor() :
+    ViewModel(),
+    ContainerHost<CalendarState, CalendarSideEffect> {
+
+    override val container = container<CalendarState, CalendarSideEffect>(CalendarState())
+}
diff --git a/feature/calendar/src/main/java/com/gamss/android/feature/calendar/navigation/CalendarKey.kt b/feature/calendar/src/main/java/com/gamss/android/feature/calendar/navigation/CalendarKey.kt
new file mode 100644
index 0000000..d21aa69
--- /dev/null
+++ b/feature/calendar/src/main/java/com/gamss/android/feature/calendar/navigation/CalendarKey.kt
@@ -0,0 +1,7 @@
+package com.gamss.android.feature.calendar.navigation
+
+import androidx.navigation3.runtime.NavKey
+import kotlinx.serialization.Serializable
+
+@Serializable
+data object CalendarKey : NavKey
diff --git a/feature/calendar/src/test/java/com/gamss/android/feature/calendar/ExampleUnitTest.kt b/feature/calendar/src/test/java/com/gamss/android/feature/calendar/ExampleUnitTest.kt
new file mode 100644
index 0000000..27615f5
--- /dev/null
+++ b/feature/calendar/src/test/java/com/gamss/android/feature/calendar/ExampleUnitTest.kt
@@ -0,0 +1,16 @@
+package com.gamss.android.feature.calendar
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+/**
+ * Example local unit test, which will execute on the development machine (host).
+ *
+ * See [testing documentation](http://d.android.com/tools/testing).
+ */
+class ExampleUnitTest {
+    @Test
+    fun addition_isCorrect() {
+        assertEquals(4, 2 + 2)
+    }
+}
diff --git a/feature/chat/build.gradle.kts b/feature/chat/build.gradle.kts
new file mode 100644
index 0000000..917fd2d
--- /dev/null
+++ b/feature/chat/build.gradle.kts
@@ -0,0 +1,61 @@
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+
+plugins {
+    alias(libs.plugins.androidLibrary)
+    alias(libs.plugins.composeCompiler)
+    alias(libs.plugins.kotlinSerialization)
+    alias(libs.plugins.ksp)
+}
+
+android {
+    namespace = "com.gamss.android.feature.chat"
+    compileSdk = libs.versions.android.compileSdk.get().toInt()
+
+    defaultConfig {
+        minSdk = libs.versions.android.minSdk.get().toInt()
+
+        testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
+    }
+    buildFeatures {
+        compose = true
+    }
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_17
+        targetCompatibility = JavaVersion.VERSION_17
+    }
+
+}
+
+kotlin {
+    compilerOptions {
+        jvmTarget = JvmTarget.JVM_17
+    }
+}
+
+dependencies {
+    implementation(libs.androidx.core.ktx)
+
+    implementation(platform(libs.compose.bom))
+    implementation(libs.compose.ui)
+    implementation(libs.compose.ui.graphics)
+    implementation(libs.compose.ui.tooling.preview)
+    implementation(libs.compose.material3)
+
+    implementation(libs.navigation3.runtime)
+    implementation(libs.kotlinx.serialization.json)
+
+    implementation(libs.androidx.lifecycle.viewmodel.ktx)
+    implementation(libs.androidx.hilt.navigation.compose)
+    implementation(libs.hilt.android)
+    ksp(libs.hilt.compiler)
+
+    implementation(libs.orbit.core)
+    implementation(libs.orbit.viewmodel)
+    implementation(libs.orbit.compose)
+
+    debugImplementation(libs.compose.ui.tooling)
+
+    testImplementation(libs.junit)
+    testImplementation(libs.orbit.test)
+    androidTestImplementation(libs.androidx.junit)
+}
\ No newline at end of file
diff --git a/feature/chat/src/androidTest/java/com/gamss/android/feature/chat/ExampleInstrumentedTest.kt b/feature/chat/src/androidTest/java/com/gamss/android/feature/chat/ExampleInstrumentedTest.kt
new file mode 100644
index 0000000..b164cd6
--- /dev/null
+++ b/feature/chat/src/androidTest/java/com/gamss/android/feature/chat/ExampleInstrumentedTest.kt
@@ -0,0 +1,24 @@
+package com.gamss.android.feature.chat
+
+import androidx.test.platform.app.InstrumentationRegistry
+import androidx.test.ext.junit.runners.AndroidJUnit4
+
+import org.junit.Test
+import org.junit.runner.RunWith
+
+import org.junit.Assert.*
+
+/**
+ * Instrumented test, which will execute on an Android device.
+ *
+ * See [testing documentation](http://d.android.com/tools/testing).
+ */
+@RunWith(AndroidJUnit4::class)
+class ExampleInstrumentedTest {
+    @Test
+    fun useAppContext() {
+        // Context of the app under test.
+        val appContext = InstrumentationRegistry.getInstrumentation().targetContext
+        assertEquals("com.gamss.android.feature.chat.test", appContext.packageName)
+    }
+}
\ No newline at end of file
diff --git a/feature/chat/src/main/AndroidManifest.xml b/feature/chat/src/main/AndroidManifest.xml
new file mode 100644
index 0000000..a5918e6
--- /dev/null
+++ b/feature/chat/src/main/AndroidManifest.xml
@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+
+</manifest>
\ No newline at end of file
diff --git a/feature/chat/src/main/java/com/gamss/android/feature/chat/ChattingListScreen.kt b/feature/chat/src/main/java/com/gamss/android/feature/chat/ChattingListScreen.kt
new file mode 100644
index 0000000..b86f56e
--- /dev/null
+++ b/feature/chat/src/main/java/com/gamss/android/feature/chat/ChattingListScreen.kt
@@ -0,0 +1,60 @@
+package com.gamss.android.feature.chat
+
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.lazy.LazyColumn
+import androidx.compose.foundation.lazy.items
+import androidx.compose.material3.CircularProgressIndicator
+import androidx.compose.material3.Divider
+import androidx.compose.material3.ListItem
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Scaffold
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.unit.dp
+import androidx.hilt.navigation.compose.hiltViewModel
+import org.orbitmvi.orbit.compose.collectAsState
+import org.orbitmvi.orbit.compose.collectSideEffect
+
+private data class DummyChat(
+    val name: String,
+    val lastMessage: String,
+)
+
+private val dummyChats = List(10) {
+    DummyChat(name = "채팅방 ${it + 1}", lastMessage = "임시 메시지 내용입니다.")
+}
+
+@Composable
+fun ChattingListScreen(
+    viewModel: ChattingListViewModel = hiltViewModel(),
+) {
+    val state by viewModel.collectAsState()
+
+    viewModel.collectSideEffect { }
+
+    Scaffold(
+        topBar = {
+            Text(
+                text = "채팅",
+                style = MaterialTheme.typography.titleLarge,
+                modifier = Modifier.padding(16.dp),
+            )
+        },
+    ) { innerPadding ->
+        if (state.isLoading) {
+            CircularProgressIndicator()
+        } else {
+            LazyColumn(modifier = Modifier.padding(innerPadding)) {
+                items(dummyChats) { chat ->
+                    ListItem(
+                        headlineContent = { Text(chat.name) },
+                        supportingContent = { Text(chat.lastMessage) },
+                    )
+                    Divider()
+                }
+            }
+        }
+    }
+}
diff --git a/feature/chat/src/main/java/com/gamss/android/feature/chat/ChattingListSideEffect.kt b/feature/chat/src/main/java/com/gamss/android/feature/chat/ChattingListSideEffect.kt
new file mode 100644
index 0000000..5349ff9
--- /dev/null
+++ b/feature/chat/src/main/java/com/gamss/android/feature/chat/ChattingListSideEffect.kt
@@ -0,0 +1,3 @@
+package com.gamss.android.feature.chat
+
+sealed interface ChattingListSideEffect
diff --git a/feature/chat/src/main/java/com/gamss/android/feature/chat/ChattingListState.kt b/feature/chat/src/main/java/com/gamss/android/feature/chat/ChattingListState.kt
new file mode 100644
index 0000000..087a0d5
--- /dev/null
+++ b/feature/chat/src/main/java/com/gamss/android/feature/chat/ChattingListState.kt
@@ -0,0 +1,5 @@
+package com.gamss.android.feature.chat
+
+data class ChattingListState(
+    val isLoading: Boolean = false,
+)
diff --git a/feature/chat/src/main/java/com/gamss/android/feature/chat/ChattingListViewModel.kt b/feature/chat/src/main/java/com/gamss/android/feature/chat/ChattingListViewModel.kt
new file mode 100644
index 0000000..fa0c732
--- /dev/null
+++ b/feature/chat/src/main/java/com/gamss/android/feature/chat/ChattingListViewModel.kt
@@ -0,0 +1,15 @@
+package com.gamss.android.feature.chat
+
+import androidx.lifecycle.ViewModel
+import dagger.hilt.android.lifecycle.HiltViewModel
+import org.orbitmvi.orbit.ContainerHost
+import org.orbitmvi.orbit.viewmodel.container
+import javax.inject.Inject
+
+@HiltViewModel
+class ChattingListViewModel @Inject constructor() :
+    ViewModel(),
+    ContainerHost<ChattingListState, ChattingListSideEffect> {
+
+    override val container = container<ChattingListState, ChattingListSideEffect>(ChattingListState())
+}
diff --git a/feature/chat/src/main/java/com/gamss/android/feature/chat/navigation/ChatKey.kt b/feature/chat/src/main/java/com/gamss/android/feature/chat/navigation/ChatKey.kt
new file mode 100644
index 0000000..518747d
--- /dev/null
+++ b/feature/chat/src/main/java/com/gamss/android/feature/chat/navigation/ChatKey.kt
@@ -0,0 +1,7 @@
+package com.gamss.android.feature.chat.navigation
+
+import androidx.navigation3.runtime.NavKey
+import kotlinx.serialization.Serializable
+
+@Serializable
+data object ChatKey : NavKey
diff --git a/feature/chat/src/test/java/com/gamss/android/feature/chat/ExampleUnitTest.kt b/feature/chat/src/test/java/com/gamss/android/feature/chat/ExampleUnitTest.kt
new file mode 100644
index 0000000..e765379
--- /dev/null
+++ b/feature/chat/src/test/java/com/gamss/android/feature/chat/ExampleUnitTest.kt
@@ -0,0 +1,16 @@
+package com.gamss.android.feature.chat
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+/**
+ * Example local unit test, which will execute on the development machine (host).
+ *
+ * See [testing documentation](http://d.android.com/tools/testing).
+ */
+class ExampleUnitTest {
+    @Test
+    fun addition_isCorrect() {
+        assertEquals(4, 2 + 2)
+    }
+}
diff --git a/feature/home/build.gradle.kts b/feature/home/build.gradle.kts
new file mode 100644
index 0000000..84a02b8
--- /dev/null
+++ b/feature/home/build.gradle.kts
@@ -0,0 +1,63 @@
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+
+plugins {
+    alias(libs.plugins.androidLibrary)
+    alias(libs.plugins.composeCompiler)
+    alias(libs.plugins.kotlinSerialization)
+    alias(libs.plugins.ksp)
+}
+
+android {
+    namespace = "com.gamss.android.feature.home"
+    compileSdk = libs.versions.android.compileSdk.get().toInt()
+
+    defaultConfig {
+        minSdk = libs.versions.android.minSdk.get().toInt()
+
+        testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
+    }
+    buildFeatures {
+        compose = true
+    }
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_17
+        targetCompatibility = JavaVersion.VERSION_17
+    }
+
+}
+
+kotlin {
+    compilerOptions {
+        jvmTarget = JvmTarget.JVM_17
+    }
+}
+
+dependencies {
+    implementation(projects.core.ui)
+
+    implementation(libs.androidx.core.ktx)
+
+    implementation(platform(libs.compose.bom))
+    implementation(libs.compose.ui)
+    implementation(libs.compose.ui.graphics)
+    implementation(libs.compose.ui.tooling.preview)
+    implementation(libs.compose.material3)
+
+    implementation(libs.navigation3.runtime)
+    implementation(libs.kotlinx.serialization.json)
+
+    implementation(libs.androidx.lifecycle.viewmodel.ktx)
+    implementation(libs.androidx.hilt.navigation.compose)
+    implementation(libs.hilt.android)
+    ksp(libs.hilt.compiler)
+
+    implementation(libs.orbit.core)
+    implementation(libs.orbit.viewmodel)
+    implementation(libs.orbit.compose)
+
+    debugImplementation(libs.compose.ui.tooling)
+
+    testImplementation(libs.junit)
+    testImplementation(libs.orbit.test)
+    androidTestImplementation(libs.androidx.junit)
+}
\ No newline at end of file
diff --git a/feature/home/src/androidTest/java/com/gamss/android/feature/home/ExampleInstrumentedTest.kt b/feature/home/src/androidTest/java/com/gamss/android/feature/home/ExampleInstrumentedTest.kt
new file mode 100644
index 0000000..45785b9
--- /dev/null
+++ b/feature/home/src/androidTest/java/com/gamss/android/feature/home/ExampleInstrumentedTest.kt
@@ -0,0 +1,24 @@
+package com.gamss.android.feature.home
+
+import androidx.test.platform.app.InstrumentationRegistry
+import androidx.test.ext.junit.runners.AndroidJUnit4
+
+import org.junit.Test
+import org.junit.runner.RunWith
+
+import org.junit.Assert.*
+
+/**
+ * Instrumented test, which will execute on an Android device.
+ *
+ * See [testing documentation](http://d.android.com/tools/testing).
+ */
+@RunWith(AndroidJUnit4::class)
+class ExampleInstrumentedTest {
+    @Test
+    fun useAppContext() {
+        // Context of the app under test.
+        val appContext = InstrumentationRegistry.getInstrumentation().targetContext
+        assertEquals("com.gamss.android.feature.home.test", appContext.packageName)
+    }
+}
\ No newline at end of file
diff --git a/feature/home/src/main/AndroidManifest.xml b/feature/home/src/main/AndroidManifest.xml
new file mode 100644
index 0000000..a5918e6
--- /dev/null
+++ b/feature/home/src/main/AndroidManifest.xml
@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+
+</manifest>
\ No newline at end of file
diff --git a/feature/home/src/main/java/com/gamss/android/feature/home/HomeScreen.kt b/feature/home/src/main/java/com/gamss/android/feature/home/HomeScreen.kt
new file mode 100644
index 0000000..68cde8b
--- /dev/null
+++ b/feature/home/src/main/java/com/gamss/android/feature/home/HomeScreen.kt
@@ -0,0 +1,62 @@
+package com.gamss.android.feature.home
+
+import android.widget.Toast
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material3.Button
+import androidx.compose.material3.CircularProgressIndicator
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Scaffold
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.unit.dp
+import androidx.hilt.navigation.compose.hiltViewModel
+import org.orbitmvi.orbit.compose.collectAsState
+import org.orbitmvi.orbit.compose.collectSideEffect
+
+@Composable
+fun HomeScreen(
+    viewModel: HomeViewModel = hiltViewModel(),
+) {
+    val state by viewModel.collectAsState()
+    val context = LocalContext.current
+
+    viewModel.collectSideEffect { sideEffect ->
+        when (sideEffect) {
+            is HomeSideEffect.ShowToast ->
+                Toast.makeText(context, sideEffect.message, Toast.LENGTH_SHORT).show()
+        }
+    }
+
+    Scaffold { innerPadding ->
+        Box(
+            modifier = Modifier
+                .fillMaxSize()
+                .padding(innerPadding),
+            contentAlignment = Alignment.Center,
+        ) {
+            if (state.isLoading) {
+                CircularProgressIndicator()
+            } else {
+                Column(horizontalAlignment = Alignment.CenterHorizontally) {
+                    Text(
+                        text = state.greeting.ifEmpty { "GAMSS" },
+                        style = MaterialTheme.typography.headlineLarge,
+                    )
+                    Spacer(modifier = Modifier.height(16.dp))
+                    Button(onClick = viewModel::loadGreeting) {
+                        Text("새로고침")
+                    }
+                }
+            }
+        }
+    }
+}
diff --git a/feature/home/src/main/java/com/gamss/android/feature/home/HomeSideEffect.kt b/feature/home/src/main/java/com/gamss/android/feature/home/HomeSideEffect.kt
new file mode 100644
index 0000000..a07bba6
--- /dev/null
+++ b/feature/home/src/main/java/com/gamss/android/feature/home/HomeSideEffect.kt
@@ -0,0 +1,5 @@
+package com.gamss.android.feature.home
+
+sealed interface HomeSideEffect {
+    data class ShowToast(val message: String) : HomeSideEffect
+}
diff --git a/feature/home/src/main/java/com/gamss/android/feature/home/HomeState.kt b/feature/home/src/main/java/com/gamss/android/feature/home/HomeState.kt
new file mode 100644
index 0000000..a59a738
--- /dev/null
+++ b/feature/home/src/main/java/com/gamss/android/feature/home/HomeState.kt
@@ -0,0 +1,6 @@
+package com.gamss.android.feature.home
+
+data class HomeState(
+    val isLoading: Boolean = false,
+    val greeting: String = "",
+)
diff --git a/feature/home/src/main/java/com/gamss/android/feature/home/HomeViewModel.kt b/feature/home/src/main/java/com/gamss/android/feature/home/HomeViewModel.kt
new file mode 100644
index 0000000..90e1927
--- /dev/null
+++ b/feature/home/src/main/java/com/gamss/android/feature/home/HomeViewModel.kt
@@ -0,0 +1,29 @@
+package com.gamss.android.feature.home
+
+import androidx.lifecycle.ViewModel
+import dagger.hilt.android.lifecycle.HiltViewModel
+import kotlinx.coroutines.delay
+import org.orbitmvi.orbit.ContainerHost
+import org.orbitmvi.orbit.viewmodel.container
+import javax.inject.Inject
+
+@HiltViewModel
+class HomeViewModel @Inject constructor() : ViewModel(), ContainerHost<HomeState, HomeSideEffect> {
+
+    override val container = container<HomeState, HomeSideEffect>(HomeState())
+
+    init {
+        loadGreeting()
+    }
+
+    fun loadGreeting() = intent {
+        reduce { state.copy(isLoading = true) }
+
+        // mock 데이터. 실제 UseCase/Repository 연동 시 교체한다.
+        delay(500)
+        val mockGreeting = "오늘 하루는 어땠나요?"
+
+        reduce { state.copy(isLoading = false, greeting = mockGreeting) }
+        postSideEffect(HomeSideEffect.ShowToast("불러오기 완료"))
+    }
+}
diff --git a/app/src/main/kotlin/com/gamss/android/app/navigation/HomeKey.kt b/feature/home/src/main/java/com/gamss/android/feature/home/navigation/HomeKey.kt
similarity index 72%
rename from app/src/main/kotlin/com/gamss/android/app/navigation/HomeKey.kt
rename to feature/home/src/main/java/com/gamss/android/feature/home/navigation/HomeKey.kt
index acb6d69..da9b979 100644
--- a/app/src/main/kotlin/com/gamss/android/app/navigation/HomeKey.kt
+++ b/feature/home/src/main/java/com/gamss/android/feature/home/navigation/HomeKey.kt
@@ -1,4 +1,4 @@
-package com.gamss.android.app.navigation
+package com.gamss.android.feature.home.navigation
 
 import androidx.navigation3.runtime.NavKey
 import kotlinx.serialization.Serializable
diff --git a/feature/home/src/test/java/com/gamss/android/feature/home/ExampleUnitTest.kt b/feature/home/src/test/java/com/gamss/android/feature/home/ExampleUnitTest.kt
new file mode 100644
index 0000000..3a399a1
--- /dev/null
+++ b/feature/home/src/test/java/com/gamss/android/feature/home/ExampleUnitTest.kt
@@ -0,0 +1,16 @@
+package com.gamss.android.feature.home
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+/**
+ * Example local unit test, which will execute on the development machine (host).
+ *
+ * See [testing documentation](http://d.android.com/tools/testing).
+ */
+class ExampleUnitTest {
+    @Test
+    fun addition_isCorrect() {
+        assertEquals(4, 2 + 2)
+    }
+}
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index e7c0352..6c8c645 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -7,15 +7,38 @@ android-compileSdk = "36"
 android-minSdk = "24"
 android-targetSdk = "36"
 androidx-activity = "1.11.0"
+androidx-hilt = "1.2.0"
 androidx-lifecycle = "2.9.4"
+lifecycle-viewmodel-navigation3 = "2.10.0"
 compose-bom = "2026.04.01"
 navigation3 = "1.1.0-rc01"
 junit = "4.13.2"
 detekt = "1.23.8"
+kotlinx-serialization = "1.11.0"
+orbit-mvi = "11.0.0"
+retrofit = "3.0.0"
+okhttp = "5.4.0"
+room = "3.0.0-alpha06"
+coil = "3.5.0"
+calendar = "2.10.0"
+firebase-bom = "34.15.0"
+firebase-crashlytics-gradle = "3.0.7"
+google-services = "4.4.4"
+androidx-credentials = "1.5.0"
+googleid = "1.1.1"
+coreKtx = "1.17.0"
+junitVersion = "1.3.0"
+espressoCore = "3.7.0"
+appcompat = "1.7.1"
+material = "1.14.0"
+runtime = "1.11.4"
 
 [libraries]
 androidx-activity-compose = { module = "androidx.activity:activity-compose", version.ref = "androidx-activity" }
+androidx-hilt-navigation-compose = { module = "androidx.hilt:hilt-navigation-compose", version.ref = "androidx-hilt" }
 androidx-lifecycle-runtime-ktx = { module = "androidx.lifecycle:lifecycle-runtime-ktx", version.ref = "androidx-lifecycle" }
+androidx-lifecycle-viewmodel-ktx = { module = "androidx.lifecycle:lifecycle-viewmodel-ktx", version.ref = "androidx-lifecycle" }
+androidx-lifecycle-viewmodel-navigation3 = { module = "androidx.lifecycle:lifecycle-viewmodel-navigation3-android", version.ref = "lifecycle-viewmodel-navigation3" }
 
 compose-bom = { module = "androidx.compose:compose-bom", version.ref = "compose-bom" }
 compose-ui = { module = "androidx.compose.ui:ui" }
@@ -23,6 +46,7 @@ compose-ui-graphics = { module = "androidx.compose.ui:ui-graphics" }
 compose-ui-tooling = { module = "androidx.compose.ui:ui-tooling" }
 compose-ui-tooling-preview = { module = "androidx.compose.ui:ui-tooling-preview" }
 compose-material3 = { module = "androidx.compose.material3:material3" }
+compose-material-icons-core = { module = "androidx.compose.material:material-icons-core" }
 
 navigation3-runtime = { module = "androidx.navigation3:navigation3-runtime", version.ref = "navigation3" }
 navigation3-ui = { module = "androidx.navigation3:navigation3-ui", version.ref = "navigation3" }
@@ -34,6 +58,42 @@ junit = { module = "junit:junit", version.ref = "junit" }
 
 detekt-formatting = { module = "io.gitlab.arturbosch.detekt:detekt-formatting", version.ref = "detekt" }
 
+kotlinx-serialization-json = { module = "org.jetbrains.kotlinx:kotlinx-serialization-json", version.ref = "kotlinx-serialization" }
+
+orbit-core = { module = "org.orbit-mvi:orbit-core", version.ref = "orbit-mvi" }
+orbit-viewmodel = { module = "org.orbit-mvi:orbit-viewmodel", version.ref = "orbit-mvi" }
+orbit-compose = { module = "org.orbit-mvi:orbit-compose", version.ref = "orbit-mvi" }
+orbit-test = { module = "org.orbit-mvi:orbit-test", version.ref = "orbit-mvi" }
+
+retrofit = { module = "com.squareup.retrofit2:retrofit", version.ref = "retrofit" }
+retrofit-converter-kotlinx-serialization = { module = "com.squareup.retrofit2:converter-kotlinx-serialization", version.ref = "retrofit" }
+okhttp = { module = "com.squareup.okhttp3:okhttp", version.ref = "okhttp" }
+okhttp-logging-interceptor = { module = "com.squareup.okhttp3:logging-interceptor", version.ref = "okhttp" }
+
+room-runtime = { module = "androidx.room3:room3-runtime", version.ref = "room" }
+room-ktx = { module = "androidx.room3:room3-ktx", version.ref = "room" }
+room-compiler = { module = "androidx.room3:room3-compiler", version.ref = "room" }
+
+coil-bom = { module = "io.coil-kt.coil3:coil-bom", version.ref = "coil" }
+coil-compose = { module = "io.coil-kt.coil3:coil-compose" }
+coil-network-okhttp = { module = "io.coil-kt.coil3:coil-network-okhttp" }
+
+calendar-compose = { module = "com.kizitonwose.calendar:compose", version.ref = "calendar" }
+
+firebase-bom = { module = "com.google.firebase:firebase-bom", version.ref = "firebase-bom" }
+firebase-analytics = { module = "com.google.firebase:firebase-analytics" }
+firebase-crashlytics = { module = "com.google.firebase:firebase-crashlytics" }
+
+androidx-credentials = { module = "androidx.credentials:credentials", version.ref = "androidx-credentials" }
+androidx-credentials-play-services-auth = { module = "androidx.credentials:credentials-play-services-auth", version.ref = "androidx-credentials" }
+googleid = { module = "com.google.android.libraries.identity.googleid:googleid", version.ref = "googleid" }
+androidx-core-ktx = { group = "androidx.core", name = "core-ktx", version.ref = "coreKtx" }
+androidx-junit = { group = "androidx.test.ext", name = "junit", version.ref = "junitVersion" }
+androidx-espresso-core = { group = "androidx.test.espresso", name = "espresso-core", version.ref = "espressoCore" }
+androidx-appcompat = { group = "androidx.appcompat", name = "appcompat", version.ref = "appcompat" }
+material = { group = "com.google.android.material", name = "material", version.ref = "material" }
+androidx-runtime = { group = "androidx.compose.runtime", name = "runtime", version.ref = "runtime" }
+
 [plugins]
 androidApplication = { id = "com.android.application", version.ref = "agp" }
 androidLibrary = { id = "com.android.library", version.ref = "agp" }
@@ -42,4 +102,6 @@ composeCompiler = { id = "org.jetbrains.kotlin.plugin.compose", version.ref = "k
 kotlinSerialization = { id = "org.jetbrains.kotlin.plugin.serialization", version.ref = "kotlin" }
 ksp = { id = "com.google.devtools.ksp", version.ref = "ksp" }
 hilt = { id = "com.google.dagger.hilt.android", version.ref = "hilt" }
+googleServices = { id = "com.google.gms.google-services", version.ref = "google-services" }
+firebaseCrashlytics = { id = "com.google.firebase.crashlytics", version.ref = "firebase-crashlytics-gradle" }
 detekt = { id = "io.gitlab.arturbosch.detekt", version.ref = "detekt" }
diff --git a/settings.gradle.kts b/settings.gradle.kts
index 4e1657e..1174dbc 100644
--- a/settings.gradle.kts
+++ b/settings.gradle.kts
@@ -19,6 +19,12 @@ enableFeaturePreview("TYPESAFE_PROJECT_ACCESSORS")
 rootProject.name = "GAMSS-Android"
 
 include(":app")
-include(":core")
+
 include(":domain")
 include(":data")
+
+include(":core:common")
+include(":core:ui")
+include(":feature:home")
+include(":feature:chat")
+include(":feature:calendar")