diff --git a/modules/auth/tests/auth.abilities.integration.tests.js b/modules/auth/tests/auth.abilities.integration.tests.js
index b11e62c33..62bc880fb 100644
--- a/modules/auth/tests/auth.abilities.integration.tests.js
+++ b/modules/auth/tests/auth.abilities.integration.tests.js
@@ -42,6 +42,14 @@ describe('Auth abilities integration tests:', () => {
     agent = request.agent(init.app);
     adminAgent = request.agent(init.app);
 
+    // clean up stale users from previous runs on shared databases
+    for (const email of [userCredentials.email, adminCredentials.email]) {
+      try {
+        const existing = await UserService.getBrut({ email });
+        if (existing) await UserService.remove(existing);
+      } catch (_) { /* cleanup – ignore errors */ }
+    }
+
     // Create a regular user
     const userRes = await agent
       .post('/api/auth/signup')
diff --git a/modules/auth/tests/auth.authorization.integration.tests.js b/modules/auth/tests/auth.authorization.integration.tests.js
index 7e7161b94..c9758666b 100644
--- a/modules/auth/tests/auth.authorization.integration.tests.js
+++ b/modules/auth/tests/auth.authorization.integration.tests.js
@@ -40,6 +40,14 @@ describe('Authorization integration tests:', () => {
     adminAgent = request.agent(init.app);
     otherAgent = request.agent(init.app);
 
+    // clean up stale users from previous runs on shared databases
+    for (const email of ['auth-test-user@test.com', 'auth-test-admin@test.com', 'auth-test-other@test.com']) {
+      try {
+        const existing = await UserService.getBrut({ email });
+        if (existing) await UserService.remove(existing);
+      } catch (_) { /* cleanup – ignore errors */ }
+    }
+
     // Create a normal user via agent
     const userRes = await agent
       .post('/api/auth/signup')
diff --git a/modules/auth/tests/auth.integration.tests.js b/modules/auth/tests/auth.integration.tests.js
index bbbec71a1..fdbffafcb 100644
--- a/modules/auth/tests/auth.integration.tests.js
+++ b/modules/auth/tests/auth.integration.tests.js
@@ -66,6 +66,14 @@ describe('Auth integration tests:', () => {
       _userEdited.email = credentials[1].email;
       _userEdited.password = credentials[1].password;
 
+      // clean up stale users from previous runs on shared databases
+      for (const email of [credentials[0].email, credentials[1].email, 'register_new_user_@test.com']) {
+        try {
+          const existing = await UserService.getBrut({ email });
+          if (existing) await UserService.remove(existing);
+        } catch (_) { /* cleanup – ignore errors */ }
+      }
+
       // add user
       try {
         const result = await agent.post('/api/auth/signup').send(_user).expect(200);
@@ -645,6 +653,11 @@ describe('Auth integration tests:', () => {
         password: credentials[0].password,
         provider: 'local',
       };
+      // clean up stale users from previous runs on shared databases
+      try {
+        const existing = await UserService.getBrut({ email: credentials[0].email });
+        if (existing) await UserService.remove(existing);
+      } catch (_) { /* cleanup – ignore errors */ }
       try {
         const result = await agent.post('/api/auth/signup').send(_user).expect(200);
         user = result.body.user;
@@ -722,6 +735,13 @@ describe('Auth integration tests:', () => {
     let secUser;
 
     beforeEach(async () => {
+      // clean up stale users from previous runs on shared databases
+      for (const email of [secEmail, 'cookieflag@test.com']) {
+        try {
+          const existing = await UserService.getBrut({ email });
+          if (existing) await UserService.remove(existing);
+        } catch (_) { /* cleanup – ignore errors */ }
+      }
       try {
         const result = await agent.post('/api/auth/signup').send({
           firstName: 'Sec',
@@ -873,6 +893,11 @@ describe('Auth integration tests:', () => {
     let verifyUser;
 
     beforeEach(async () => {
+      // clean up stale users from previous runs on shared databases
+      try {
+        const existing = await UserService.getBrut({ email: verifyEmail });
+        if (existing) await UserService.remove(existing);
+      } catch (_) { /* cleanup – ignore errors */ }
       try {
         const result = await agent.post('/api/auth/signup').send({
           firstName: 'Verify',
@@ -998,6 +1023,11 @@ describe('Auth integration tests:', () => {
     let lockUser;
 
     beforeEach(async () => {
+      // clean up stale users from previous runs on shared databases
+      try {
+        const existing = await UserService.getBrut({ email: lockEmail });
+        if (existing) await UserService.remove(existing);
+      } catch (_) { /* cleanup – ignore errors */ }
       try {
         const result = await agent.post('/api/auth/signup').send({
           firstName: 'Lock',
diff --git a/modules/auth/tests/auth.signup.organization.integration.tests.js b/modules/auth/tests/auth.signup.organization.integration.tests.js
index e83f9fa85..5070be60b 100644
--- a/modules/auth/tests/auth.signup.organization.integration.tests.js
+++ b/modules/auth/tests/auth.signup.organization.integration.tests.js
@@ -44,6 +44,18 @@ describe('Auth signup organization integration tests:', () => {
     } catch (_) { /* cleanup — ignore errors */ }
   };
 
+  /**
+   * Remove a user by email if they exist (cleanup stale data from previous runs).
+   * @param {string} email - email address of the user to purge
+   * @returns {Promise<void>}
+   */
+  const purgeUser = async (email) => {
+    try {
+      const existing = await UserService.getBrut({ email });
+      if (existing) await cleanupUser(existing);
+    } catch (_) { /* cleanup – ignore errors */ }
+  };
+
   beforeAll(async () => {
     try {
       const init = await bootstrap();
@@ -66,6 +78,8 @@ describe('Auth signup organization integration tests:', () => {
       config.organizations = { enabled: false, autoCreate: true, domainMatching: true };
 
       let user;
+      // clean up stale users from previous runs on shared databases
+      await purgeUser('silent-org@test.com');
       try {
         const result = await agent
           .post('/api/auth/signup')
@@ -108,6 +122,9 @@ describe('Auth signup organization integration tests:', () => {
       // First, create an existing organization with a specific domain
       let firstUser;
       let secondUser;
+      // clean up stale users from previous runs on shared databases
+      await purgeUser('first@matchdomain.com');
+      await purgeUser('second@matchdomain.com');
       try {
         // Sign up first user to create the org with domain
         const result1 = await agent
@@ -162,6 +179,8 @@ describe('Auth signup organization integration tests:', () => {
       config.organizations = { enabled: true, autoCreate: true, domainMatching: true };
 
       let user;
+      // clean up stale users from previous runs on shared databases
+      await purgeUser('solo@uniquedomain123.com');
       try {
         const result = await agent
           .post('/api/auth/signup')
@@ -200,6 +219,8 @@ describe('Auth signup organization integration tests:', () => {
       config.organizations = { enabled: true, autoCreate: true, domainMatching: false };
 
       let user;
+      // clean up stale users from previous runs on shared databases
+      await purgeUser('personal@somecompany.com');
       try {
         const result = await agent
           .post('/api/auth/signup')
@@ -238,6 +259,8 @@ describe('Auth signup organization integration tests:', () => {
       config.organizations = { enabled: true, autoCreate: false, domainMatching: true };
 
       let user;
+      // clean up stale users from previous runs on shared databases
+      await purgeUser('manual@setup.com');
       try {
         const result = await agent
           .post('/api/auth/signup')
@@ -273,6 +296,8 @@ describe('Auth signup organization integration tests:', () => {
       config.organizations = { enabled: false, autoCreate: true, domainMatching: true };
 
       let user;
+      // clean up stale users from previous runs on shared databases
+      await purgeUser('response-check@test.com');
       try {
         const result = await agent
           .post('/api/auth/signup')