diff --git a/Cargo.toml b/Cargo.toml
index 100ae95..cc45d1c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -12,3 +12,4 @@ hex = "0.4"
 
 [dev-dependencies]
 tempfile = "3"
+surf = { version = "2", default-features = false, features = ["h1-client"] }
diff --git a/docs/README.md b/docs/README.md
index 088c2aa..67eb733 100644
--- a/docs/README.md
+++ b/docs/README.md
@@ -24,6 +24,7 @@ Voir aussi:
 - `depannage.md`
 - `performance.md`
 - `api_json_spec.md`
+- `api_contrats.md`
 
 ## REX technique
 
diff --git a/docs/api_contrats.md b/docs/api_contrats.md
new file mode 100644
index 0000000..6a7f3bd
--- /dev/null
+++ b/docs/api_contrats.md
@@ -0,0 +1,21 @@
+# Contrats API
+
+## Garanties de Contrat
+- Content-Type JSON, réponses structurées.
+- Clé: 64 hex (validation stricte), sinon 400.
+- Valeur: hex valide, sinon 400.
+- Conflit de clé: 409 si la clé existe déjà.
+- TTL: min 60, max 31 536 000; par défaut 86 400 si non `--permanent`.
+- Récupération:
+  - 200 avec `{ key, value }` si trouvée.
+  - 400 si clé invalide.
+  - 404 si absente.
+
+## Couverture de Tests
+- Stockage et récupération (succès).
+- Conflit de clé.
+- Suppression des expirés via nettoyage.
+- HTTP `/store`: succès, conflit, clé invalide, valeur invalide.
+- HTTP `/retrieve`: succès, clé invalide, clé absente.
+
+Voir `api_json_spec.md` pour les schémas et contraintes détaillés.
diff --git a/src/lib.rs b/src/lib.rs
index 9d1a5e0..a415121 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -4,7 +4,7 @@ use async_std::path::Path;
 use async_std::stream::StreamExt;
 use serde::{Deserialize, Serialize};
 use std::time::{Duration, SystemTime, UNIX_EPOCH};
-use tide::StatusCode;
+use tide::{StatusCode, Request, Response};
 
 #[derive(Clone, Debug)]
 pub struct StorageService {
@@ -142,3 +142,111 @@ pub fn system_time_to_unix(system_time: SystemTime) -> u64 {
 pub fn unix_to_system_time(unix_timestamp: u64) -> SystemTime {
     UNIX_EPOCH + Duration::from_secs(unix_timestamp)
 }
+
+#[derive(Deserialize)]
+pub struct StoreRequest {
+    pub key: String,
+    pub value: String,
+    pub ttl: Option<u64>,
+}
+
+#[derive(Serialize)]
+pub struct ApiResponse { pub message: String }
+
+#[derive(Serialize)]
+pub struct RetrieveResponse { pub key: String, pub value: String }
+
+pub async fn handle_store(mut req: Request<StorageService>, no_ttl_permanent: bool) -> tide::Result<Response> {
+    let data: StoreRequest = match req.body_json().await {
+        Ok(data) => data,
+        Err(e) => {
+            return Ok(Response::builder(StatusCode::BadRequest)
+                .body(format!("Invalid request: {}", e))
+                .build());
+        }
+    };
+
+    if data.key.len() != 64 || !data.key.chars().all(|c| c.is_ascii_hexdigit()) {
+        return Ok(Response::builder(StatusCode::BadRequest)
+            .body("Invalid key: must be a 32 bytes hex string.".to_string())
+            .build());
+    }
+
+    let live_for: Option<Duration> = if let Some(ttl) = data.ttl {
+        if ttl < 60 {
+            return Ok(Response::builder(StatusCode::BadRequest)
+                .body(format!("Invalid ttl: must be at least {} seconds.", 60))
+                .build());
+        } else if ttl > 31_536_000 {
+            return Ok(Response::builder(StatusCode::BadRequest)
+                .body(format!("Invalid ttl: must be at most {} seconds.", 31_536_000))
+                .build());
+        }
+        Some(Duration::from_secs(ttl))
+    } else if no_ttl_permanent {
+        None
+    } else {
+        Some(Duration::from_secs(86_400))
+    };
+
+    let expires_at: Option<SystemTime> = match live_for {
+        Some(lf) => Some(
+            SystemTime::now()
+                .checked_add(lf)
+                .ok_or(tide::Error::from_str(StatusCode::BadRequest, "Invalid ttl"))?
+        ),
+        None => None,
+    };
+
+    let value_bytes = match hex::decode(&data.value) {
+        Ok(value) => value,
+        Err(e) => {
+            return Ok(Response::builder(StatusCode::BadRequest)
+                .body(format!("Invalid request: {}", e))
+                .build());
+        }
+    };
+
+    let svc = req.state();
+    match svc.store_data(&data.key, &value_bytes, expires_at).await {
+        Ok(()) => Ok(Response::builder(StatusCode::Ok)
+            .body(serde_json::to_value(&ApiResponse {
+                message: "Data stored successfully.".to_string(),
+            })?)
+            .build()),
+        Err(e) => Ok(Response::builder(e.status())
+            .body(serde_json::to_value(&ApiResponse {
+                message: e.to_string(),
+            })?)
+            .build()),
+    }
+}
+
+pub async fn handle_retrieve(req: Request<StorageService>) -> tide::Result<Response> {
+    let key: String = req.param("key")?.to_string();
+
+    if key.len() != 64 || !key.chars().all(|c| c.is_ascii_hexdigit()) {
+        return Ok(Response::builder(StatusCode::BadRequest)
+            .body("Invalid key: must be a 32 bytes hex string.".to_string())
+            .build());
+    }
+
+    let svc = req.state();
+    match svc.retrieve_data(&key).await {
+        Ok(value) => {
+            let encoded_value = hex::encode(value);
+            Ok(Response::builder(StatusCode::Ok)
+                .body(serde_json::to_value(&RetrieveResponse { key, value: encoded_value })?)
+                .build())
+        }
+        Err(e) => Ok(Response::builder(StatusCode::NotFound).body(e).build()),
+    }
+}
+
+pub fn create_app(no_ttl_permanent: bool, storage_dir: impl Into<String>) -> tide::Server<StorageService> {
+    let svc = StorageService::new(storage_dir);
+    let mut app = tide::with_state(svc);
+    app.at("/store").post(move |req| handle_store(req, no_ttl_permanent));
+    app.at("/retrieve/:key").get(handle_retrieve);
+    app
+}
diff --git a/src/main.rs b/src/main.rs
index b8b052c..94bf171 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,128 +1,12 @@
-use serde::{Deserialize, Serialize};
-use std::time::{Duration, SystemTime};
 use std::env;
 use async_std::task;
 use async_std::fs::create_dir_all;
-use tide::{Request, Response, StatusCode};
-use sdk_storage::StorageService;
+use sdk_storage::{StorageService, create_app};
 
 const STORAGE_DIR: &str = "./storage";
 const PORT: u16 = 8081;
-const MIN_TTL: u64 = 60;
 const DEFAULT_TTL: u64 = 86400;
-const MAX_TTL: u64 = 31_536_000;
 
-#[derive(Deserialize)]
-struct StoreRequest {
-    key: String,
-    value: String,
-    ttl: Option<u64>,
-}
-
-#[derive(Serialize)]
-struct ApiResponse { message: String }
-
-#[derive(Serialize)]
-struct RetrieveResponse { key: String, value: String }
-
-async fn handle_store(mut req: Request<StorageService>, no_ttl_permanent: bool) -> tide::Result<Response> {
-    // Parse the JSON body
-    let data: StoreRequest = match req.body_json().await {
-        Ok(data) => data,
-        Err(e) => {
-            return Ok(Response::builder(StatusCode::BadRequest)
-                .body(format!("Invalid request: {}", e))
-                .build());
-        }
-    };
-
-    // Validate the key
-    if data.key.len() != 64 || !data.key.chars().all(|c| c.is_ascii_hexdigit()) {
-        return Ok(Response::builder(StatusCode::BadRequest)
-            .body("Invalid key: must be a 32 bytes hex string.".to_string())
-            .build());
-    }
-
-    // Validate the ttl
-    let live_for: Option<Duration> = if let Some(ttl) = data.ttl {
-        if ttl < MIN_TTL {
-            return Ok(Response::builder(StatusCode::BadRequest)
-                .body(format!(
-                    "Invalid ttl: must be at least {} seconds.",
-                    MIN_TTL
-                ))
-                .build());
-        } else if ttl > MAX_TTL {
-            return Ok(Response::builder(StatusCode::BadRequest)
-                .body(format!("Invalid ttl: must be at most {} seconds.", MAX_TTL))
-                .build());
-        }
-        Some(Duration::from_secs(ttl))
-    } else if no_ttl_permanent {
-        // When no_ttl_permanent is true, requests without TTL are permanent
-        None
-    } else {
-        Some(Duration::from_secs(DEFAULT_TTL))
-    };
-
-    let expires_at: Option<SystemTime> = match live_for {
-        Some(lf) => Some(
-            SystemTime::now()
-                .checked_add(lf)
-                .ok_or(tide::Error::from_str(StatusCode::BadRequest, "Invalid ttl"))?
-        ),
-        None => None,
-    };
-
-    // Decode hex value
-    let value_bytes = match hex::decode(&data.value) {
-        Ok(value) => value,
-        Err(e) => {
-            return Ok(Response::builder(StatusCode::BadRequest)
-                .body(format!("Invalid request: {}", e))
-                .build());
-        }
-    };
-
-    // Store the data
-    let svc = req.state();
-    match svc.store_data(&data.key, &value_bytes, expires_at).await {
-        Ok(()) => Ok(Response::builder(StatusCode::Ok)
-            .body(serde_json::to_value(&ApiResponse {
-                message: "Data stored successfully.".to_string(),
-            })?)
-            .build()),
-        Err(e) => Ok(Response::builder(e.status())
-            .body(serde_json::to_value(&ApiResponse {
-                message: e.to_string(),
-            })?)
-            .build()),
-    }
-}
-
-async fn handle_retrieve(req: Request<StorageService>) -> tide::Result<Response> {
-    let key: String = req.param("key")?.to_string();
-
-    if key.len() != 64 || !key.chars().all(|c| c.is_ascii_hexdigit()) {
-        return Ok(Response::builder(StatusCode::BadRequest)
-            .body("Invalid key: must be a 32 bytes hex string.".to_string())
-            .build());
-    }
-
-    let svc = req.state();
-    match svc.retrieve_data(&key).await {
-        Ok(value) => {
-            let encoded_value = hex::encode(value);
-            Ok(Response::builder(StatusCode::Ok)
-                .body(serde_json::to_value(&RetrieveResponse {
-                    key,
-                    value: encoded_value,
-                })?)
-                .build())
-        }
-        Err(e) => Ok(Response::builder(StatusCode::NotFound).body(e).build()),
-    }
-}
 
 #[async_std::main]
 async fn main() -> tide::Result<()> {
@@ -150,9 +34,7 @@ async fn main() -> tide::Result<()> {
         }
     });
 
-    let mut app = tide::with_state(svc);
-    app.at("/store").post(move |req| handle_store(req, no_ttl_permanent));
-    app.at("/retrieve/:key").get(handle_retrieve);
+    let mut app = create_app(no_ttl_permanent, STORAGE_DIR);
     app.listen(format!("0.0.0.0:{}", PORT)).await?;
 
     println!("Server running at http://0.0.0.0:{}", PORT);