security: prevent re-use of refresh token (reduce surface for any stolen token)

Security: session hardening

  Refresh token rotation with theft detection (family_id)
  - Added family_id column to auth.sessions (migration 20260507000000_session_family.sql) grouping all tokens issued from the same login into a family
  - On refresh, the new session inherits the parent's family_id
  - If a revoked token is replayed (indicates the token was stolen after rotation), the entire family is immediately invalidated and a warning is logged — forcing re-authentication on all devices

  SameSite=Strict on refresh cookie
  - Access cookie stays SameSite=Lax (needed for top-level navigation)
  - Refresh cookie upgraded to SameSite=Strict — it is only ever used for explicit POST to /api/auth/refresh, never via cross-site navigation

  Refresh token TTL: 30 days → 7 days
  - With rotation, active sessions auto-renew and effectively never expire
  - Inactive sessions expire after 7 days instead of 30, reducing the theft window

src/domain/entities/session.rs

@@ -11,6 +11,9 @@ pub struct Session {
     user_agent: Option<String>,
     created_at: DateTime<Utc>,
     revoked: bool,
+    /// Groups all tokens issued from the same original login.
+    /// Replaying a revoked token from this family triggers full-family revocation.
+    family_id: Uuid,
 }
 
 impl Session {
@@ -20,6 +23,7 @@ impl Session {
         ip_address: Option<String>,
         user_agent: Option<String>,
         expires_in_days: i64,
+        family_id: Uuid,
     ) -> Self {
         if refresh_token.is_empty() {
             panic!("Session refresh_token cannot be empty");
@@ -35,6 +39,7 @@ impl Session {
             user_agent,
             created_at: now,
             revoked: false,
+            family_id,
         }
     }
 
@@ -48,6 +53,7 @@ impl Session {
         user_agent: Option<String>,
         created_at: DateTime<Utc>,
         revoked: bool,
+        family_id: Uuid,
     ) -> Self {
         Self {
             id,
@@ -58,6 +64,7 @@ impl Session {
             user_agent,
             created_at,
             revoked,
+            family_id,
         }
     }
 
@@ -101,4 +108,8 @@ impl Session {
     pub fn revoke(&mut self) {
         self.revoked = true;
     }
+
+    pub fn family_id(&self) -> Uuid {
+        self.family_id
+    }
 }

src/domain/repositories/session_repository.rs

@@ -52,6 +52,9 @@ pub trait SessionRepository: Send + Sync + 'static {
     /// Revokes all sessions for a user
     async fn revoke_all_user_sessions(&self, user_id: Uuid) -> SessionRepositoryResult<u64>;
 
+    /// Revokes all sessions in a token family (theft response)
+    async fn revoke_session_family(&self, family_id: Uuid) -> SessionRepositoryResult<u64>;
+
     /// Deletes expired sessions
     async fn delete_expired_sessions(&self) -> SessionRepositoryResult<u64>;
 }