diff --git a/src/api/errors.rs b/src/api/errors.rs
new file mode 100644
index 0000000..a48025f
--- /dev/null
+++ b/src/api/errors.rs
@@ -0,0 +1,66 @@
+use crate::databases::postgres::errors::DbError;
+use crate::providers::ollama::errors::OllamaError;
+
+use axum::http::StatusCode;
+use axum::response::{IntoResponse, Response};
+
+pub enum ApiError {
+    Db(DbError),
+    Ollama(OllamaError),
+}
+
+impl From<DbError> for ApiError {
+    fn from(e: DbError) -> Self {
+        ApiError::Db(e)
+    }
+}
+
+impl From<OllamaError> for ApiError {
+    fn from(e: OllamaError) -> Self {
+        ApiError::Ollama(e)
+    }
+}
+
+impl IntoResponse for ApiError {
+    fn into_response(self) -> Response {
+        let (status, msg) = match self {
+            ApiError::Db(db_err) => match db_err {
+                DbError::Connection(_) => (
+                    StatusCode::INTERNAL_SERVER_ERROR,
+                    "database connection error".to_string(),
+                ),
+                DbError::Timeout => (StatusCode::REQUEST_TIMEOUT, "database timeout".to_string()),
+                DbError::NotFound => (StatusCode::NOT_FOUND, "not found".to_string()),
+            },
+
+            ApiError::Ollama(ollama_err) => match ollama_err {
+                OllamaError::MissingPrompt => (
+                    StatusCode::BAD_REQUEST,
+                    "prompt is required and cannot be empty".to_string(),
+                ),
+                OllamaError::MissingModel => (
+                    StatusCode::BAD_REQUEST,
+                    "model is required and cannot be empty".to_string(),
+                ),
+                OllamaError::ModelNotFound(m) => (
+                    StatusCode::UNPROCESSABLE_ENTITY,
+                    format!("model '{m}' is not available — run `ollama pull {m}` first"),
+                ),
+                OllamaError::MissingKeepAlive => (
+                    StatusCode::BAD_REQUEST,
+                    "keep alive is required and cannot be empty".to_string(),
+                ),
+                OllamaError::InvalidKeepAlive(v) => {
+                    (StatusCode::BAD_REQUEST, format!("invalid keep_alive '{v}'"))
+                }
+                OllamaError::MissingMessages => (
+                    StatusCode::BAD_REQUEST,
+                    "messages array with at least one user message is required".to_string(),
+                ),
+                OllamaError::Http(e) => (StatusCode::INTERNAL_SERVER_ERROR, e.to_string()),
+            },
+        };
+
+        (status, msg).into_response()
+    }
+}
diff --git a/src/api/mod.rs b/src/api/mod.rs
new file mode 100644
index 0000000..629e98f
--- /dev/null
+++ b/src/api/mod.rs
@@ -0,0 +1 @@
+pub mod errors;
diff --git a/src/databases/postgres/api_key/mod.rs b/src/databases/postgres/api_key/mod.rs
new file mode 100644
index 0000000..84c032e
--- /dev/null
+++ b/src/databases/postgres/api_key/mod.rs
@@ -0,0 +1 @@
+pub mod queries;
diff --git a/src/databases/postgres/api_key.rs b/src/databases/postgres/api_key/queries.rs
similarity index 86%
rename from src/databases/postgres/api_key.rs
rename to src/databases/postgres/api_key/queries.rs
index a087c50..d38b7d7 100644
--- a/src/databases/postgres/api_key.rs
+++ b/src/databases/postgres/api_key/queries.rs
@@ -1,4 +1,5 @@
-use super::errors::DbError;
+use crate::databases::postgres::errors::DbError;
+
 use sqlx::PgPool;
 use uuid::Uuid;
 
diff --git a/src/databases/postgres/chat/mod.rs b/src/databases/postgres/chat/mod.rs
new file mode 100644
index 0000000..0333ab5
--- /dev/null
+++ b/src/databases/postgres/chat/mod.rs
@@ -0,0 +1,2 @@
+pub mod queries;
+pub mod types;
diff --git a/src/databases/postgres/chat.rs b/src/databases/postgres/chat/queries.rs
similarity index 87%
rename from src/databases/postgres/chat.rs
rename to src/databases/postgres/chat/queries.rs
index c7fdc5d..facc050 100644
--- a/src/databases/postgres/chat.rs
+++ b/src/databases/postgres/chat/queries.rs
@@ -1,5 +1,6 @@
-use super::errors::DbError;
-use crate::dto::postgres;
+use crate::databases::postgres::chat::types;
+use crate::databases::postgres::errors::DbError;
+
 use sqlx::{Acquire, PgPool};
 use uuid::Uuid;
 
@@ -39,17 +40,11 @@ where
     Ok(rec.id)
 }
 
-#[derive(Debug)]
-pub enum ConversationState {
-    Existing(Uuid),
-    Created(Uuid),
-}
-
 pub async fn get_or_create_conversation(
     pool: &PgPool,
     conversation_id: Option<Uuid>,
     user_id: Uuid,
-) -> Result<ConversationState, DbError> {
+) -> Result<types::ConversationState, DbError> {
     tracing::debug!("Testing conversation");
 
     let mut tx = pool.begin().await?;
@@ -65,9 +60,11 @@ pub async fn get_or_create_conversation(
         match conversation_id {
             Some(id) => {
                 validate_conversation(&mut *conn, id).await?;
-                ConversationState::Existing(id)
+                types::ConversationState::Existing(id)
+            }
+            None => {
+                types::ConversationState::Created(create_conversation(&mut *conn, user_id).await?)
             }
-            None => ConversationState::Created(create_conversation(&mut *conn, user_id).await?),
         }
     };
 
@@ -101,21 +98,12 @@ pub async fn set_conversation_title(
     Ok(())
 }
 
-#[derive(Debug, Clone, sqlx::Type)]
-#[sqlx(type_name = "text")]
-#[sqlx(rename_all = "lowercase")]
-pub enum MessageRole {
-    User,
-    Assistant,
-    System,
-}
-
 pub async fn insert_message(
     pool: &PgPool,
     user_id: Uuid,
     conversation_id: Uuid,
     parent_id: Option<Uuid>,
-    role: MessageRole,
+    role: types::MessageRole,
     content: &str,
     tokens: Option<u32>,
 ) -> Result<Uuid, DbError> {
@@ -135,7 +123,7 @@ pub async fn insert_message(
         "#,
         conversation_id,
         parent_id,
-        role as MessageRole,
+        role as types::MessageRole,
         content,
         tokens.unwrap_or(0) as i32
     )
@@ -178,8 +166,8 @@ pub async fn get_conversations_entries(
     pool: &PgPool,
     user_id: Uuid,
     limit: i64,
-    before: Option<chrono::DateTime<chrono::Utc>>, // cursor
-) -> Result<Vec<postgres::ConversationSummary>, DbError> {
+    before: Option<chrono::DateTime<chrono::Utc>>,
+) -> Result<Vec<types::ConversationSummary>, DbError> {
     let mut tx = pool.begin().await?;
 
     sqlx::query("SELECT set_config('app.current_user_id', $1::text, true)")
@@ -188,7 +176,7 @@ pub async fn get_conversations_entries(
         .await?;
 
     let rows = sqlx::query_as!(
-        postgres::ConversationSummary,
+        types::ConversationSummary,
         r#"
         SELECT id, title, created_at, updated_at
         FROM chat.conversation
@@ -214,7 +202,7 @@ pub async fn get_conversation_messages(
     conversation_id: Uuid,
     limit: i64,
     before: Option<chrono::DateTime<chrono::Utc>>,
-) -> Result<Vec<postgres::MessageSummary>, DbError> {
+) -> Result<Vec<types::MessageSummary>, DbError> {
     let mut conn = pool.acquire().await?;
 
     sqlx::query(r#"SELECT set_config('app.current_user_id', $1::text, true)"#)
@@ -223,7 +211,7 @@ pub async fn get_conversation_messages(
         .await?;
 
     let rows = sqlx::query_as!(
-        postgres::MessageSummary,
+        types::MessageSummary,
         r#"
         SELECT id, parent_id, role, content, created_at, tokens
         FROM chat.message
diff --git a/src/dto/postgres.rs b/src/databases/postgres/chat/types.rs
similarity index 67%
rename from src/dto/postgres.rs
rename to src/databases/postgres/chat/types.rs
index 17fb63f..c2f0583 100644
--- a/src/dto/postgres.rs
+++ b/src/databases/postgres/chat/types.rs
@@ -1,6 +1,21 @@
 use serde::Serialize;
 use uuid::Uuid;
 
+#[derive(Debug, Clone, sqlx::Type)]
+#[sqlx(type_name = "text")]
+#[sqlx(rename_all = "lowercase")]
+pub enum MessageRole {
+    User,
+    Assistant,
+    System,
+}
+
+#[derive(Debug)]
+pub enum ConversationState {
+    Existing(Uuid),
+    Created(Uuid),
+}
+
 #[derive(Debug, sqlx::FromRow, Serialize)]
 pub struct ConversationSummary {
     pub id: Uuid,
diff --git a/src/databases/postgres/errors.rs b/src/databases/postgres/errors.rs
index 32e6128..6534304 100644
--- a/src/databases/postgres/errors.rs
+++ b/src/databases/postgres/errors.rs
@@ -1,4 +1,3 @@
-use axum::http::StatusCode;
 use thiserror::Error;
 
 #[derive(Debug, Error)]
@@ -12,14 +11,3 @@ pub enum DbError {
     #[error("not found")]
     NotFound,
 }
-
-pub fn into_http_response(e: DbError) -> (StatusCode, String) {
-    match e {
-        DbError::Connection(_) => (
-            StatusCode::INTERNAL_SERVER_ERROR,
-            "database connection error".to_string(),
-        ),
-        DbError::Timeout => (StatusCode::REQUEST_TIMEOUT, "database timeout".to_string()),
-        DbError::NotFound => (StatusCode::NOT_FOUND, "not found".to_string()),
-    }
-}
diff --git a/src/databases/postgres/mod.rs b/src/databases/postgres/mod.rs
index e70c180..4db98f0 100644
--- a/src/databases/postgres/mod.rs
+++ b/src/databases/postgres/mod.rs
@@ -1,5 +1,6 @@
-pub mod api_key;
-pub mod chat;
 pub mod errors;
 pub mod pool;
+
+pub mod api_key;
+pub mod chat;
 pub mod user;
diff --git a/src/databases/postgres/user/mod.rs b/src/databases/postgres/user/mod.rs
new file mode 100644
index 0000000..84c032e
--- /dev/null
+++ b/src/databases/postgres/user/mod.rs
@@ -0,0 +1 @@
+pub mod queries;
diff --git a/src/databases/postgres/user.rs b/src/databases/postgres/user/queries.rs
similarity index 87%
rename from src/databases/postgres/user.rs
rename to src/databases/postgres/user/queries.rs
index 8e0a535..8e6a0ef 100644
--- a/src/databases/postgres/user.rs
+++ b/src/databases/postgres/user/queries.rs
@@ -1,4 +1,5 @@
-use super::errors::DbError;
+use crate::databases::postgres::errors::DbError;
+
 use sqlx::PgPool;
 use uuid::Uuid;
 
diff --git a/src/dto/api.rs b/src/dto/api.rs
index 1b934a7..a2c8306 100644
--- a/src/dto/api.rs
+++ b/src/dto/api.rs
@@ -234,8 +234,8 @@ pub struct ConversationQuery {
 
 #[derive(Debug, Serialize)]
 pub struct ConversationListResponse {
-    pub conversations: Vec<super::postgres::ConversationSummary>,
-    pub has_more: bool, // client knows if there are more pages
+    pub conversations: Vec<crate::databases::postgres::chat::types::ConversationSummary>,
+    pub has_more: bool,
 }
 
 #[derive(Debug, Deserialize)]
@@ -246,6 +246,6 @@ pub struct MessageQuery {
 
 #[derive(Debug, Serialize)]
 pub struct MessageListResponse {
-    pub messages: Vec<super::postgres::MessageSummary>,
+    pub messages: Vec<crate::databases::postgres::chat::types::MessageSummary>,
     pub has_more: bool,
 }
diff --git a/src/dto/mod.rs b/src/dto/mod.rs
index 46e927b..b6fe8b2 100644
--- a/src/dto/mod.rs
+++ b/src/dto/mod.rs
@@ -1,3 +1,2 @@
 pub mod api;
 pub mod ollama;
-pub mod postgres;
diff --git a/src/lib.rs b/src/lib.rs
index fe7cb5c..ea8d223 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,3 +1,4 @@
+pub mod api;
 pub mod databases;
 pub mod dto;
 pub mod middlewares;
diff --git a/src/main.rs b/src/main.rs
index 2ada6cb..b5f7acb 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,3 +1,4 @@
+mod api;
 mod databases;
 mod docs;
 mod dto;
diff --git a/src/middlewares/auth/middleware.rs b/src/middlewares/auth/middleware.rs
index e972dfb..a437cc4 100644
--- a/src/middlewares/auth/middleware.rs
+++ b/src/middlewares/auth/middleware.rs
@@ -5,7 +5,9 @@ use axum::{
     response::{IntoResponse, Response},
 };
 
-use crate::databases::postgres::{api_key::update_last_access, user::ensure_user_exists};
+use crate::databases::postgres::{
+    api_key::queries::update_last_access, user::queries::ensure_user_exists,
+};
 use crate::middlewares::auth::apikey::{ApiKeyClaims, ApiKeyClaimsRoles};
 use crate::middlewares::auth::keycloak::{KeycloakClaims, get_jwks, refresh_jwks, validate_token};
 use crate::state::app_state::AppState;
diff --git a/src/routes/v1/chat.rs b/src/routes/v1/chat.rs
index 2e1d518..83491bb 100644
--- a/src/routes/v1/chat.rs
+++ b/src/routes/v1/chat.rs
@@ -1,6 +1,6 @@
 use crate::{
-    databases::postgres::chat::ConversationState, dto::api::BaseLLMRequest,
-    middlewares::auth::middleware::Auth, providers::ollama::client::OllamaProvider,
+    dto::api::BaseLLMRequest, middlewares::auth::middleware::Auth,
+    providers::ollama::client::OllamaProvider,
 };
 use axum::{
     Json,
@@ -14,13 +14,14 @@ use sqlx::PgPool;
 use tokio_stream::StreamExt;
 use uuid::Uuid;
 
-use crate::databases::postgres::chat::{
+use crate::api::errors::ApiError;
+use crate::databases::postgres::chat::queries::{
     get_conversation_messages, get_conversations_entries, get_or_create_conversation,
-    set_conversation_title, update_message_tokens,
+    insert_message, set_conversation_title, update_message_tokens,
 };
-use crate::databases::postgres::{chat, errors};
+use crate::databases::postgres::chat::types::{ConversationState, MessageRole};
+use crate::databases::postgres::errors;
 use crate::dto::api;
-use crate::dto::api::CompletionRequest;
 use crate::providers::ollama::errors::into_http_response;
 use crate::state::app_state::AppState;
 
@@ -89,11 +90,9 @@ async fn ensure_conversation(
     auth: &Auth,
     conversation_id: Option<Uuid>,
     first_message: &str,
-) -> Result<Uuid, (axum::http::StatusCode, String)> {
+) -> Result<Uuid, ApiError> {
     let conversation_state =
-        get_or_create_conversation(&state.postgres, conversation_id, auth.user_id())
-            .await
-            .map_err(crate::databases::postgres::errors::into_http_response)?;
+        get_or_create_conversation(&state.postgres, conversation_id, auth.user_id()).await?;
 
     let id = match conversation_state {
         ConversationState::Existing(uuid) => uuid,
@@ -127,14 +126,10 @@ async fn handle_stream(
     auth: Auth,
     body: api::ChatRequest,
     conversation_id: Option<Uuid>,
-) -> Result<Response, (axum::http::StatusCode, String)> {
+) -> Result<Response, ApiError> {
     // Handle anonymous (API key) path early — no DB logging
     let Some(conv_id) = conversation_id else {
-        let stream = state
-            .ollama
-            .chat_completions_stream(&body)
-            .await
-            .map_err(into_http_response)?;
+        let stream = state.ollama.chat_completions_stream(&body).await?;
 
         let plain_stream = stream.map(
             |item| -> Result<Event, crate::providers::ollama::errors::OllamaError> {
@@ -163,8 +158,7 @@ async fn handle_stream(
             .unwrap_or(""),
         None,
     )
-    .await
-    .map_err(errors::into_http_response)?;
+    .await?;
 
     let start_event = api::StreamEvent::Start(api::StartEventData {
         conversation_id: conv_id,
@@ -275,12 +269,8 @@ async fn handle_non_stream(
     auth: Auth,
     body: api::ChatRequest,
     conversation_id: Option<Uuid>,
-) -> Result<Response, (axum::http::StatusCode, String)> {
-    let mut response = state
-        .ollama
-        .chat_completions(&body)
-        .await
-        .map_err(into_http_response)?;
+) -> Result<Response, ApiError> {
+    let mut response = state.ollama.chat_completions(&body).await?;
 
     response.conversation_id = conversation_id;
 
@@ -296,8 +286,7 @@ async fn handle_non_stream(
                 .unwrap_or(""),
             response.usage.map(|u| u.prompt_tokens),
         )
-        .await
-        .map_err(errors::into_http_response)?;
+        .await?;
 
         log_assistant_message(
             &state.postgres,
@@ -307,8 +296,7 @@ async fn handle_non_stream(
             &response.choices[0].message.content,
             response.usage.map(|u| u.completion_tokens),
         )
-        .await
-        .map_err(errors::into_http_response)?;
+        .await?;
     }
 
     Ok(Json(response).into_response())
@@ -360,7 +348,7 @@ pub async fn chat_completions(
     State(state): State<AppState>,
     Extension(auth): Extension<Auth>,
     Json(mut body): Json<api::ChatRequest>,
-) -> Result<Response, (axum::http::StatusCode, String)> {
+) -> Result<Response, ApiError> {
     tracing::debug!("Received /chat/completion with body {:?}", body);
 
     let conversation_id = if matches!(&auth, Auth::Jwt(_)) {
@@ -378,8 +366,7 @@ pub async fn chat_completions(
                     depth as i64,
                     None, // no cursor — fetch the most recent N messages
                 )
-                .await
-                .map_err(errors::into_http_response)?;
+                .await?;
 
                 // Map MessageSummary → api::Message and prepend to the outgoing request
                 let history_messages: Vec<api::Message> = history
@@ -410,7 +397,7 @@ pub async fn chat_completions(
 }
 
 async fn generate_conversation_title(ollama: &OllamaProvider, first_message: &str) -> String {
-    let request = CompletionRequest {
+    let request = api::CompletionRequest {
         base: BaseLLMRequest {
             model: "llama3:latest".to_string(),
             ..Default::default()
@@ -438,12 +425,12 @@ async fn log_user_message(
     content: &str,
     tokens: Option<u32>,
 ) -> Result<Uuid, errors::DbError> {
-    chat::insert_message(
+    insert_message(
         pool,
         user_id,
         conversation_id,
         parent_id,
-        chat::MessageRole::User,
+        MessageRole::User,
         content,
         tokens,
     )
@@ -458,12 +445,12 @@ async fn log_assistant_message(
     content: &str,
     tokens: Option<u32>,
 ) -> Result<Uuid, errors::DbError> {
-    chat::insert_message(
+    insert_message(
         pool,
         user_id,
         conversation_id,
         Some(parent_id),
-        chat::MessageRole::Assistant,
+        MessageRole::Assistant,
         content,
         tokens,
     )
@@ -475,8 +462,7 @@ pub async fn get_conversations(
     State(state): State<AppState>,
     Extension(auth): Extension<Auth>,
     Query(params): Query<api::ConversationQuery>,
-) -> Result<Json<api::ConversationListResponse>, (axum::http::StatusCode, Json<api::ErrorResponse>)>
-{
+) -> Result<Json<api::ConversationListResponse>, ApiError> {
     tracing::debug!("Conversation hit: {:?}", auth);
 
     let conversations = get_conversations_entries(
@@ -485,11 +471,7 @@ pub async fn get_conversations(
         params.limit.unwrap_or(20),
         params.before,
     )
-    .await
-    .map_err(|e| {
-        let (code, msg) = errors::into_http_response(e);
-        (code, Json(api::ErrorResponse::new(msg)))
-    })?;
+    .await?;
 
     let has_more = conversations.len() == params.limit.unwrap_or(20) as usize;
 
@@ -504,7 +486,7 @@ pub async fn get_messages(
     Extension(auth): Extension<Auth>,
     Path(conversation_id): Path<Uuid>,
     Query(params): Query<api::MessageQuery>,
-) -> Result<Json<api::MessageListResponse>, (axum::http::StatusCode, Json<api::ErrorResponse>)> {
+) -> Result<Json<api::MessageListResponse>, ApiError> {
     tracing::debug!("Messages hit: {:?}", auth);
 
     let messages = get_conversation_messages(
@@ -514,11 +496,7 @@ pub async fn get_messages(
         params.limit.unwrap_or(50),
         params.before,
     )
-    .await
-    .map_err(|e| {
-        let (code, msg) = errors::into_http_response(e);
-        (code, Json(api::ErrorResponse::new(msg)))
-    })?;
+    .await?;
 
     let has_more = messages.len() == params.limit.unwrap_or(50) as usize;