diff --git a/IMPLEMENTATION_PLAN.md b/IMPLEMENTATION_PLAN.md
index 9d027bc..8f72fb6 100644
--- a/IMPLEMENTATION_PLAN.md
+++ b/IMPLEMENTATION_PLAN.md
@@ -12,7 +12,7 @@
 
 - [x] **Task 2 — EnvelopeCreateResult class + createEnvelope() method:** Add `EnvelopeCreateResult` inner class and `createEnvelope(Id caseId, String accountCode, String templateId)` to `DocusignESignatureService`. (FR-002)
 
-- [ ] **Task 3 — Tests for createEnvelope():** Add test coverage in `DocusignESignatureServiceTest` — success path (mock 201), failure path (mock 400), blank email guard. (NFR-001, TC-001, TC-002)
+- [x] **Task 3 — Tests for createEnvelope():** Add test coverage in `DocusignESignatureServiceTest` — success path (mock 201), failure path (mock 400), blank email guard. (NFR-001, TC-001, TC-002)
 
 - [ ] **Task 4 — persistEnvelopeResult() + CaseContext extension:** Add `persistEnvelopeResult()` to `CLMAdminService`. Extend `CaseContext` inner class and `getCaseContext()` SOQL to include the 5 eSignature fields. (FR-003, FR-004)
 
diff --git a/force-app/main/default/classes/DocusignESignatureServiceTest.cls b/force-app/main/default/classes/DocusignESignatureServiceTest.cls
index 3fcd8e0..39cb611 100644
--- a/force-app/main/default/classes/DocusignESignatureServiceTest.cls
+++ b/force-app/main/default/classes/DocusignESignatureServiceTest.cls
@@ -147,4 +147,92 @@ private class DocusignESignatureServiceTest {
             DocusignESignatureService.buildEndpoint('/v2.1/accounts', 'Esignature_Demo_NamedCreds')
         );
     }
+
+    private class CreateEnvelopeSuccessMock implements HttpCalloutMock {
+        public HttpResponse respond(HttpRequest req) {
+            HttpResponse res = new HttpResponse();
+            res.setHeader('Content-Type', 'application/json');
+            res.setStatusCode(201);
+            res.setBody('{"envelopeId":"abc-123","status":"sent","uri":"/v2.1/accounts/12345678/envelopes/abc-123"}');
+            return res;
+        }
+    }
+
+    private class CreateEnvelopeFailureMock implements HttpCalloutMock {
+        public HttpResponse respond(HttpRequest req) {
+            HttpResponse res = new HttpResponse();
+            res.setHeader('Content-Type', 'application/json');
+            res.setStatusCode(400);
+            res.setBody('{"errorCode":"TEMPLATE_NOT_IN_ACCOUNT","message":"The template specified is not in the account."}');
+            return res;
+        }
+    }
+
+    @IsTest
+    static void createEnvelopeReturnsSuccessResultOnHttp201() {
+        Appraiser_Case__c appraiserCase = new Appraiser_Case__c(
+            Appraiser_Field_Review_Date__c = Date.today(),
+            Appraiser_Email__c = 'appraiser@example.com',
+            Appraiser_Name__c = 'Jamie Carter'
+        );
+        insert appraiserCase;
+
+        Test.setMock(HttpCalloutMock.class, new CreateEnvelopeSuccessMock());
+
+        Test.startTest();
+        DocusignESignatureService.EnvelopeCreateResult result = DocusignESignatureService.createEnvelope(
+            appraiserCase.Id,
+            'DTC_CLM_Demo',
+            'tmpl-001'
+        );
+        Test.stopTest();
+
+        System.assertEquals(true, result.success);
+        System.assertEquals('abc-123', result.envelopeId);
+        System.assertEquals('sent', result.status);
+    }
+
+    @IsTest
+    static void createEnvelopeReturnsFailureResultOnHttp400() {
+        Appraiser_Case__c appraiserCase = new Appraiser_Case__c(
+            Appraiser_Field_Review_Date__c = Date.today(),
+            Appraiser_Email__c = 'appraiser@example.com',
+            Appraiser_Name__c = 'Jamie Carter'
+        );
+        insert appraiserCase;
+
+        Test.setMock(HttpCalloutMock.class, new CreateEnvelopeFailureMock());
+
+        Test.startTest();
+        DocusignESignatureService.EnvelopeCreateResult result = DocusignESignatureService.createEnvelope(
+            appraiserCase.Id,
+            'DTC_CLM_Demo',
+            'tmpl-bad'
+        );
+        Test.stopTest();
+
+        System.assertEquals(false, result.success);
+        System.assertNotEquals(null, result.errorMessage);
+        System.assert(result.errorMessage.contains('400'));
+    }
+
+    @IsTest
+    static void createEnvelopeReturnsEarlyWhenEmailIsBlank() {
+        Appraiser_Case__c appraiserCase = new Appraiser_Case__c(
+            Appraiser_Field_Review_Date__c = Date.today()
+        );
+        insert appraiserCase;
+
+        Test.startTest();
+        DocusignESignatureService.EnvelopeCreateResult result = DocusignESignatureService.createEnvelope(
+            appraiserCase.Id,
+            'DTC_CLM_Demo',
+            'tmpl-001'
+        );
+        Test.stopTest();
+
+        System.assertEquals(false, result.success);
+        System.assertNotEquals(null, result.errorMessage);
+        System.assert(result.errorMessage.toLowerCase().contains('email'));
+    }
 }