diff --git a/composeApp/src/commonMain/kotlin/com/avinal/memos/api/ApiResult.kt b/composeApp/src/commonMain/kotlin/com/avinal/memos/api/ApiResult.kt
new file mode 100644
index 0000000..73fa4ba
--- /dev/null
+++ b/composeApp/src/commonMain/kotlin/com/avinal/memos/api/ApiResult.kt
@@ -0,0 +1,27 @@
+package com.avinal.memos.api
+
+sealed class ApiResult<out T> {
+    data class Success<T>(val data: T) : ApiResult<T>()
+    data class Error(val code: Int, val message: String) : ApiResult<Nothing>()
+    data class NetworkError(val exception: Throwable) : ApiResult<Nothing>()
+}
+
+inline fun <T, R> ApiResult<T>.map(transform: (T) -> R): ApiResult<R> = when (this) {
+    is ApiResult.Success -> ApiResult.Success(transform(data))
+    is ApiResult.Error -> this
+    is ApiResult.NetworkError -> this
+}
+
+inline fun <T> ApiResult<T>.onSuccess(action: (T) -> Unit): ApiResult<T> {
+    if (this is ApiResult.Success) action(data)
+    return this
+}
+
+inline fun <T> ApiResult<T>.onError(action: (String) -> Unit): ApiResult<T> {
+    when (this) {
+        is ApiResult.Error -> action(message)
+        is ApiResult.NetworkError -> action(exception.message ?: "Network error")
+        else -> {}
+    }
+    return this
+}
diff --git a/composeApp/src/commonMain/kotlin/com/avinal/memos/api/HttpClientFactory.kt b/composeApp/src/commonMain/kotlin/com/avinal/memos/api/HttpClientFactory.kt
new file mode 100644
index 0000000..413eb5c
--- /dev/null
+++ b/composeApp/src/commonMain/kotlin/com/avinal/memos/api/HttpClientFactory.kt
@@ -0,0 +1,33 @@
+package com.avinal.memos.api
+
+import io.ktor.client.HttpClient
+import io.ktor.client.plugins.HttpSend
+import io.ktor.client.plugins.contentnegotiation.ContentNegotiation
+import io.ktor.client.plugins.plugin
+import io.ktor.http.HttpHeaders
+import io.ktor.serialization.kotlinx.json.json
+import kotlinx.serialization.json.Json
+
+object HttpClientFactory {
+
+    fun create(tokenProvider: () -> String?): HttpClient {
+        val client = HttpClient {
+            install(ContentNegotiation) {
+                json(Json {
+                    ignoreUnknownKeys = true
+                    isLenient = true
+                    encodeDefaults = true
+                })
+            }
+        }
+
+        client.plugin(HttpSend).intercept { request ->
+            tokenProvider()?.let { token ->
+                request.headers.append(HttpHeaders.Authorization, "Bearer $token")
+            }
+            execute(request)
+        }
+
+        return client
+    }
+}
diff --git a/composeApp/src/commonMain/kotlin/com/avinal/memos/api/MemosApiClient.kt b/composeApp/src/commonMain/kotlin/com/avinal/memos/api/MemosApiClient.kt
new file mode 100644
index 0000000..3033d96
--- /dev/null
+++ b/composeApp/src/commonMain/kotlin/com/avinal/memos/api/MemosApiClient.kt
@@ -0,0 +1,130 @@
+package com.avinal.memos.api
+
+import com.avinal.memos.api.model.CreateMemoRequest
+import com.avinal.memos.api.model.FieldMask
+import com.avinal.memos.api.model.ListMemosResponse
+import com.avinal.memos.api.model.MemoDto
+import com.avinal.memos.api.model.ReactionDto
+import com.avinal.memos.api.model.UpsertReactionRequest
+import com.avinal.memos.api.model.UpdateMemoBody
+import com.avinal.memos.api.model.UpdateMemoRequest
+import com.avinal.memos.api.model.UserDto
+import io.ktor.client.HttpClient
+import io.ktor.client.call.body
+import io.ktor.client.request.delete
+import io.ktor.client.request.get
+import io.ktor.client.request.parameter
+import io.ktor.client.request.patch
+import io.ktor.client.request.post
+import io.ktor.client.request.setBody
+import io.ktor.client.statement.bodyAsText
+import io.ktor.http.ContentType
+import io.ktor.http.contentType
+import io.ktor.http.isSuccess
+
+class MemosApiClient(
+    private val httpClient: HttpClient,
+    val baseUrlProvider: () -> String,
+) {
+    private fun url(path: String): String = "${baseUrlProvider().trimEnd('/')}/api/v1$path"
+
+    suspend fun getMe(): ApiResult<UserDto> = apiCall {
+        httpClient.get(url("/auth/me")).body()
+    }
+
+    suspend fun listMemos(
+        pageSize: Int = 20,
+        pageToken: String = "",
+        filter: String = "",
+    ): ApiResult<ListMemosResponse> = apiCall {
+        httpClient.get(url("/memos")) {
+            parameter("pageSize", pageSize)
+            if (pageToken.isNotEmpty()) parameter("pageToken", pageToken)
+            if (filter.isNotEmpty()) parameter("filter", filter)
+        }.body()
+    }
+
+    suspend fun getMemo(id: String): ApiResult<MemoDto> = apiCall {
+        httpClient.get(url("/memos/$id")).body()
+    }
+
+    suspend fun createMemo(
+        content: String,
+        visibility: String = "PRIVATE",
+    ): ApiResult<MemoDto> = apiCall {
+        httpClient.post(url("/memos")) {
+            contentType(ContentType.Application.Json)
+            setBody(CreateMemoRequest(content = content, visibility = visibility))
+        }.body()
+    }
+
+    suspend fun updateMemo(
+        id: String,
+        content: String? = null,
+        visibility: String? = null,
+        pinned: Boolean? = null,
+        state: String? = null,
+    ): ApiResult<MemoDto> = apiCall {
+        val paths = buildList {
+            if (content != null) add("content")
+            if (visibility != null) add("visibility")
+            if (pinned != null) add("pinned")
+            if (state != null) add("state")
+        }
+        httpClient.patch(url("/memos/$id")) {
+            parameter("updateMask", paths.joinToString(","))
+            contentType(ContentType.Application.Json)
+            setBody(UpdateMemoBody(
+                content = content,
+                visibility = visibility,
+                pinned = pinned,
+                state = state,
+            ))
+        }.body()
+    }
+
+    suspend fun searchMemos(query: String): ApiResult<ListMemosResponse> = apiCall {
+        httpClient.get(url("/memos")) {
+            parameter("pageSize", 50)
+            parameter("filter", "content.contains(\"$query\")")
+        }.body()
+    }
+
+    suspend fun upsertReaction(memoId: String, reactionType: String): ApiResult<ReactionDto> = apiCall {
+        httpClient.post(url("/memos/$memoId/reactions")) {
+            contentType(ContentType.Application.Json)
+            setBody(UpsertReactionRequest(
+                reaction = ReactionDto(reactionType = reactionType, contentId = "memos/$memoId")
+            ))
+        }.body()
+    }
+
+    suspend fun deleteReaction(memoId: String, reactionId: String): ApiResult<Unit> = apiCall {
+        val response = httpClient.delete(url("/memos/$memoId/reactions/$reactionId"))
+        if (!response.status.isSuccess()) {
+            throw ApiException(response.status.value, response.bodyAsText())
+        }
+    }
+
+    suspend fun deleteMemo(id: String): ApiResult<Unit> = apiCall {
+        val response = httpClient.delete(url("/memos/$id"))
+        if (!response.status.isSuccess()) {
+            throw ApiException(response.status.value, response.bodyAsText())
+        }
+    }
+
+    private suspend inline fun <T> apiCall(block: () -> T): ApiResult<T> =
+        try {
+            ApiResult.Success(block())
+        } catch (e: ApiException) {
+            ApiResult.Error(e.code, e.message ?: "Unknown error")
+        } catch (e: io.ktor.client.plugins.ClientRequestException) {
+            ApiResult.Error(e.response.status.value, e.message)
+        } catch (e: io.ktor.client.plugins.ServerResponseException) {
+            ApiResult.Error(e.response.status.value, e.message)
+        } catch (e: Exception) {
+            ApiResult.NetworkError(e)
+        }
+}
+
+class ApiException(val code: Int, message: String) : Exception(message)
diff --git a/composeApp/src/commonMain/kotlin/com/avinal/memos/api/model/Mappers.kt b/composeApp/src/commonMain/kotlin/com/avinal/memos/api/model/Mappers.kt
new file mode 100644
index 0000000..d1d31b0
--- /dev/null
+++ b/composeApp/src/commonMain/kotlin/com/avinal/memos/api/model/Mappers.kt
@@ -0,0 +1,64 @@
+package com.avinal.memos.api.model
+
+import com.avinal.memos.domain.Attachment
+import com.avinal.memos.domain.Memo
+import com.avinal.memos.domain.MemoVisibility
+import com.avinal.memos.domain.Reaction
+import com.avinal.memos.domain.User
+import kotlin.time.Instant
+
+private fun String.extractId(): String = substringAfterLast("/")
+
+fun MemoDto.toDomain(): Memo = Memo(
+    id = name.extractId(),
+    uid = uid,
+    content = content,
+    visibility = MemoVisibility.fromApiString(visibility),
+    pinned = pinned,
+    state = state,
+    createTime = parseTimestamp(createTime),
+    updateTime = parseTimestamp(updateTime),
+    displayTime = parseTimestamp(displayTime.ifEmpty { updateTime }),
+    creator = creator.extractId(),
+    hasTaskList = property?.hasTaskList ?: false,
+    hasIncompleteTasks = property?.hasIncompleteTasks ?: false,
+    title = property?.title ?: "",
+    tags = tags,
+    snippet = snippet,
+    attachments = attachments.map { it.toDomain() },
+    reactions = reactions.map { it.toDomain() },
+)
+
+fun AttachmentDto.toDomain(): Attachment = Attachment(
+    name = name,
+    filename = filename,
+    mimeType = type,
+    size = size.toLongOrNull() ?: 0L,
+    externalLink = externalLink,
+)
+
+fun ReactionDto.toDomain(): Reaction = Reaction(
+    id = name.extractId(),
+    creator = creator.extractId(),
+    reactionType = reactionType,
+)
+
+fun UserDto.toDomain(): User = User(
+    id = name.extractId(),
+    username = username,
+    nickname = nickname,
+    email = email,
+    avatarUrl = avatarUrl,
+    role = role,
+)
+
+private fun parseTimestamp(value: String): Instant =
+    if (value.isNotEmpty()) {
+        try {
+            Instant.parse(value)
+        } catch (_: Exception) {
+            Instant.DISTANT_PAST
+        }
+    } else {
+        Instant.DISTANT_PAST
+    }
diff --git a/composeApp/src/commonMain/kotlin/com/avinal/memos/api/model/MemoDto.kt b/composeApp/src/commonMain/kotlin/com/avinal/memos/api/model/MemoDto.kt
new file mode 100644
index 0000000..d29cf37
--- /dev/null
+++ b/composeApp/src/commonMain/kotlin/com/avinal/memos/api/model/MemoDto.kt
@@ -0,0 +1,96 @@
+package com.avinal.memos.api.model
+
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class MemoDto(
+    val name: String = "",
+    val uid: String = "",
+    val creator: String = "",
+    val createTime: String = "",
+    val updateTime: String = "",
+    val displayTime: String = "",
+    val content: String = "",
+    val state: String = "NORMAL",
+    val visibility: String = "PRIVATE",
+    val pinned: Boolean = false,
+    val parent: String = "",
+    val property: MemoPropertyDto? = null,
+    val tags: List<String> = emptyList(),
+    val snippet: String = "",
+    val attachments: List<AttachmentDto> = emptyList(),
+    val reactions: List<ReactionDto> = emptyList(),
+    val relations: List<RelationDto> = emptyList(),
+)
+
+@Serializable
+data class MemoPropertyDto(
+    val hasLink: Boolean = false,
+    val hasTaskList: Boolean = false,
+    val hasCode: Boolean = false,
+    val hasIncompleteTasks: Boolean = false,
+    val title: String = "",
+)
+
+@Serializable
+data class AttachmentDto(
+    val name: String = "",
+    val filename: String = "",
+    val type: String = "",
+    val size: String = "0",
+    val externalLink: String = "",
+    val createTime: String = "",
+    val memo: String = "",
+)
+
+@Serializable
+data class ReactionDto(
+    val name: String = "",
+    val creator: String = "",
+    val contentId: String = "",
+    val reactionType: String = "",
+    val createTime: String = "",
+)
+
+@Serializable
+data class RelationDto(
+    val memo: String = "",
+    val relatedMemo: String = "",
+    val type: String = "",
+)
+
+@Serializable
+data class ListMemosResponse(
+    val memos: List<MemoDto> = emptyList(),
+    val nextPageToken: String = "",
+)
+
+@Serializable
+data class CreateMemoRequest(
+    val content: String,
+    val visibility: String = "PRIVATE",
+)
+
+@Serializable
+data class UpdateMemoBody(
+    val content: String? = null,
+    val visibility: String? = null,
+    val pinned: Boolean? = null,
+    val state: String? = null,
+)
+
+@Serializable
+data class UpdateMemoRequest(
+    val memo: UpdateMemoBody,
+    val updateMask: FieldMask,
+)
+
+@Serializable
+data class FieldMask(
+    val paths: List<String>,
+)
+
+@Serializable
+data class UpsertReactionRequest(
+    val reaction: ReactionDto,
+)
diff --git a/composeApp/src/commonMain/kotlin/com/avinal/memos/api/model/UserDto.kt b/composeApp/src/commonMain/kotlin/com/avinal/memos/api/model/UserDto.kt
new file mode 100644
index 0000000..5ac1aab
--- /dev/null
+++ b/composeApp/src/commonMain/kotlin/com/avinal/memos/api/model/UserDto.kt
@@ -0,0 +1,15 @@
+package com.avinal.memos.api.model
+
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class UserDto(
+    val name: String = "",
+    val role: String = "USER",
+    val username: String = "",
+    val email: String = "",
+    val nickname: String = "",
+    val avatarUrl: String = "",
+    val createTime: String = "",
+    val updateTime: String = "",
+)
diff --git a/composeApp/src/commonMain/kotlin/com/avinal/memos/domain/AuthRepository.kt b/composeApp/src/commonMain/kotlin/com/avinal/memos/domain/AuthRepository.kt
new file mode 100644
index 0000000..ba4dd3f
--- /dev/null
+++ b/composeApp/src/commonMain/kotlin/com/avinal/memos/domain/AuthRepository.kt
@@ -0,0 +1,57 @@
+package com.avinal.memos.domain
+
+import com.avinal.memos.api.ApiResult
+import com.avinal.memos.api.MemosApiClient
+import com.avinal.memos.api.model.toDomain
+import com.avinal.memos.util.TokenStore
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.coroutines.flow.map
+
+class AuthRepository(
+    private val apiClient: MemosApiClient,
+    private val tokenStore: TokenStore,
+) {
+    private val _currentUser = MutableStateFlow<User?>(null)
+    val currentUser: StateFlow<User?> = _currentUser.asStateFlow()
+
+    val isLoggedIn: Flow<Boolean> = tokenStore.accessToken.map { it != null }
+
+    suspend fun login(serverUrl: String, token: String): ApiResult<User> {
+        val originalBaseUrl = apiClient.baseUrlProvider
+        val tempClient = MemosApiClient(
+            httpClient = com.avinal.memos.api.HttpClientFactory.create { token },
+            baseUrlProvider = { serverUrl },
+        )
+
+        return when (val result = tempClient.getMe()) {
+            is ApiResult.Success -> {
+                val user = result.data.toDomain()
+                tokenStore.saveCredentials(serverUrl, token)
+                _currentUser.value = user
+                ApiResult.Success(user)
+            }
+            is ApiResult.Error -> result
+            is ApiResult.NetworkError -> result
+        }
+    }
+
+    suspend fun validateToken(): ApiResult<User> {
+        return when (val result = apiClient.getMe()) {
+            is ApiResult.Success -> {
+                val user = result.data.toDomain()
+                _currentUser.value = user
+                ApiResult.Success(user)
+            }
+            is ApiResult.Error -> result
+            is ApiResult.NetworkError -> result
+        }
+    }
+
+    suspend fun logout() {
+        tokenStore.clear()
+        _currentUser.value = null
+    }
+}
diff --git a/composeApp/src/commonMain/kotlin/com/avinal/memos/domain/Memo.kt b/composeApp/src/commonMain/kotlin/com/avinal/memos/domain/Memo.kt
new file mode 100644
index 0000000..8a6a823
--- /dev/null
+++ b/composeApp/src/commonMain/kotlin/com/avinal/memos/domain/Memo.kt
@@ -0,0 +1,39 @@
+package com.avinal.memos.domain
+
+import kotlin.time.Instant
+
+data class Memo(
+    val id: String,
+    val uid: String,
+    val content: String,
+    val visibility: MemoVisibility,
+    val pinned: Boolean,
+    val state: String,
+    val createTime: Instant,
+    val updateTime: Instant,
+    val displayTime: Instant,
+    val creator: String,
+    val hasTaskList: Boolean,
+    val hasIncompleteTasks: Boolean,
+    val title: String,
+    val tags: List<String>,
+    val snippet: String,
+    val attachments: List<Attachment> = emptyList(),
+    val reactions: List<Reaction> = emptyList(),
+)
+
+data class Attachment(
+    val name: String,
+    val filename: String,
+    val mimeType: String,
+    val size: Long,
+    val externalLink: String,
+) {
+    val isImage: Boolean get() = mimeType.startsWith("image/")
+}
+
+data class Reaction(
+    val id: String,
+    val creator: String,
+    val reactionType: String,
+)
diff --git a/composeApp/src/commonMain/kotlin/com/avinal/memos/domain/MemoRepository.kt b/composeApp/src/commonMain/kotlin/com/avinal/memos/domain/MemoRepository.kt
new file mode 100644
index 0000000..5400a2b
--- /dev/null
+++ b/composeApp/src/commonMain/kotlin/com/avinal/memos/domain/MemoRepository.kt
@@ -0,0 +1,167 @@
+package com.avinal.memos.domain
+
+import com.avinal.memos.api.ApiResult
+import com.avinal.memos.api.MemosApiClient
+import com.avinal.memos.api.model.toDomain
+import com.avinal.memos.db.dao.MemoDao
+import com.avinal.memos.db.entity.toEntity
+import com.avinal.memos.db.entity.toDomain
+import kotlin.time.Clock
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.IO
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.launch
+
+class MemoRepository(
+    private val apiClient: MemosApiClient,
+    private val memoDao: MemoDao,
+) {
+    private var nextPageToken: String = ""
+    private var hasMorePages: Boolean = true
+    private var lastFetchTime: Long = 0L
+
+    private fun nowMillis(): Long = Clock.System.now().toEpochMilliseconds()
+
+    private fun isCacheStale(): Boolean = (nowMillis() - lastFetchTime) > CACHE_TTL_MS
+
+    fun observeMemos(): Flow<List<Memo>> {
+        if (isCacheStale()) {
+            CoroutineScope(Dispatchers.IO).launch { refreshMemos() }
+        }
+        return memoDao.observeAll().map { entities -> entities.map { it.toDomain() } }
+    }
+
+    fun observeMemo(id: String): Flow<Memo?> =
+        memoDao.observeById(id).map { it?.toDomain() }
+
+    suspend fun getMemo(id: String): Memo? {
+        val cached = memoDao.getById(id)
+        if (cached != null) return cached.toDomain()
+        return when (val result = apiClient.getMemo(id)) {
+            is ApiResult.Success -> {
+                val memo = result.data.toDomain()
+                memoDao.upsert(memo.toEntity(nowMillis()))
+                memo
+            }
+            else -> null
+        }
+    }
+
+    suspend fun refreshMemos(): ApiResult<List<Memo>> {
+        nextPageToken = ""
+        hasMorePages = true
+        return when (val result = apiClient.listMemos(pageSize = 50)) {
+            is ApiResult.Success -> {
+                val memos = result.data.memos.map { it.toDomain() }
+                val now = nowMillis()
+                lastFetchTime = now
+                memoDao.upsertAll(memos.map { it.toEntity(now) })
+                nextPageToken = result.data.nextPageToken
+                hasMorePages = nextPageToken.isNotEmpty()
+                ApiResult.Success(memos)
+            }
+            is ApiResult.Error -> result
+            is ApiResult.NetworkError -> result
+        }
+    }
+
+    suspend fun loadNextPage(): ApiResult<List<Memo>> {
+        if (!hasMorePages) return ApiResult.Success(emptyList())
+        return when (val result = apiClient.listMemos(pageSize = 50, pageToken = nextPageToken)) {
+            is ApiResult.Success -> {
+                val memos = result.data.memos.map { it.toDomain() }
+                val now = nowMillis()
+                memoDao.upsertAll(memos.map { it.toEntity(now) })
+                nextPageToken = result.data.nextPageToken
+                hasMorePages = nextPageToken.isNotEmpty()
+                ApiResult.Success(memos)
+            }
+            is ApiResult.Error -> result
+            is ApiResult.NetworkError -> result
+        }
+    }
+
+    suspend fun createMemo(
+        content: String,
+        visibility: MemoVisibility = MemoVisibility.PRIVATE,
+    ): ApiResult<Memo> {
+        return when (val result = apiClient.createMemo(content, visibility.toApiString())) {
+            is ApiResult.Success -> {
+                val memo = result.data.toDomain()
+                memoDao.upsert(memo.toEntity(nowMillis()))
+                ApiResult.Success(memo)
+            }
+            is ApiResult.Error -> result
+            is ApiResult.NetworkError -> result
+        }
+    }
+
+    suspend fun updateMemo(
+        id: String,
+        content: String? = null,
+        visibility: MemoVisibility? = null,
+        pinned: Boolean? = null,
+    ): ApiResult<Memo> {
+        return when (val result = apiClient.updateMemo(
+            id = id,
+            content = content,
+            visibility = visibility?.toApiString(),
+            pinned = pinned,
+        )) {
+            is ApiResult.Success -> {
+                val memo = result.data.toDomain()
+                memoDao.upsert(memo.toEntity(nowMillis()))
+                ApiResult.Success(memo)
+            }
+            is ApiResult.Error -> result
+            is ApiResult.NetworkError -> result
+        }
+    }
+
+    suspend fun reactToMemo(memoId: String, emoji: String): ApiResult<Unit> {
+        return when (apiClient.upsertReaction(memoId, emoji)) {
+            is ApiResult.Success -> {
+                refreshMemos()
+                ApiResult.Success(Unit)
+            }
+            is ApiResult.Error -> ApiResult.Error(0, "Failed to react")
+            is ApiResult.NetworkError -> ApiResult.NetworkError(Exception("Network error"))
+        }
+    }
+
+    suspend fun archiveMemo(id: String): ApiResult<Memo> {
+        return when (val result = apiClient.updateMemo(id = id, state = "ARCHIVED")) {
+            is ApiResult.Success -> {
+                val memo = result.data.toDomain()
+                memoDao.deleteById(id)
+                ApiResult.Success(memo)
+            }
+            is ApiResult.Error -> result
+            is ApiResult.NetworkError -> result
+        }
+    }
+
+    suspend fun deleteMemo(id: String): ApiResult<Unit> {
+        return when (val result = apiClient.deleteMemo(id)) {
+            is ApiResult.Success -> {
+                memoDao.deleteById(id)
+                result
+            }
+            is ApiResult.Error -> result
+            is ApiResult.NetworkError -> result
+        }
+    }
+
+    suspend fun clearCache() {
+        memoDao.deleteAll()
+        lastFetchTime = 0L
+        nextPageToken = ""
+        hasMorePages = true
+    }
+
+    companion object {
+        private const val CACHE_TTL_MS = 5 * 60 * 1000L
+    }
+}
diff --git a/composeApp/src/commonMain/kotlin/com/avinal/memos/domain/MemoVisibility.kt b/composeApp/src/commonMain/kotlin/com/avinal/memos/domain/MemoVisibility.kt
new file mode 100644
index 0000000..47c6504
--- /dev/null
+++ b/composeApp/src/commonMain/kotlin/com/avinal/memos/domain/MemoVisibility.kt
@@ -0,0 +1,12 @@
+package com.avinal.memos.domain
+
+enum class MemoVisibility {
+    PRIVATE, PROTECTED, PUBLIC;
+
+    fun toApiString(): String = name
+
+    companion object {
+        fun fromApiString(value: String): MemoVisibility =
+            entries.firstOrNull { it.name == value } ?: PRIVATE
+    }
+}
diff --git a/composeApp/src/commonMain/kotlin/com/avinal/memos/domain/Task.kt b/composeApp/src/commonMain/kotlin/com/avinal/memos/domain/Task.kt
new file mode 100644
index 0000000..745434b
--- /dev/null
+++ b/composeApp/src/commonMain/kotlin/com/avinal/memos/domain/Task.kt
@@ -0,0 +1,17 @@
+package com.avinal.memos.domain
+
+import kotlinx.datetime.LocalDate
+
+data class Task(
+    val id: String,
+    val memoId: String,
+    val lineIndex: Int,
+    val text: String,
+    val rawText: String = text,
+    val originalLine: String = "",
+    val isCompleted: Boolean,
+    val dueDate: LocalDate? = null,
+    val priority: Int? = null,
+    val labels: List<String> = emptyList(),
+    val lists: List<String> = emptyList(),
+)
diff --git a/composeApp/src/commonMain/kotlin/com/avinal/memos/domain/User.kt b/composeApp/src/commonMain/kotlin/com/avinal/memos/domain/User.kt
new file mode 100644
index 0000000..c237547
--- /dev/null
+++ b/composeApp/src/commonMain/kotlin/com/avinal/memos/domain/User.kt
@@ -0,0 +1,10 @@
+package com.avinal.memos.domain
+
+data class User(
+    val id: String,
+    val username: String,
+    val nickname: String,
+    val email: String,
+    val avatarUrl: String,
+    val role: String,
+)