diff --git a/docs/package.json b/docs/package.json
index c694856e1..ae9980271 100644
--- a/docs/package.json
+++ b/docs/package.json
@@ -15,6 +15,7 @@
     "debug": "JEKYLL_ENV=development BUNDLE_GEMFILE=Gemfile bundle exec jekyll serve --config _config.yml,_config.dev.yml,_config.version.yml --limit_posts 100 --trace",
     "generate-includes": "./generate-includes.sh",
     "lint": "echo \"Documentation module has no code to lint\"",
+    "lint:fix": "echo \"Documentation module has no code to lint\"",
     "test:unit": "echo \"Documentation module has no unit tests\"",
     "typecheck": "echo \"Documentation module has no typescript to typecheck\""
   },
diff --git a/infrastructure/terraform/components/api/module_lambda_letter_updates_transformer.tf b/infrastructure/terraform/components/api/module_lambda_letter_updates_transformer.tf
index d30c8c84a..52a444ec4 100644
--- a/infrastructure/terraform/components/api/module_lambda_letter_updates_transformer.tf
+++ b/infrastructure/terraform/components/api/module_lambda_letter_updates_transformer.tf
@@ -35,7 +35,8 @@ module "letter_updates_transformer" {
   log_subscription_role_arn = local.acct.log_subscription_role_arn
 
   lambda_env_vars = merge(local.common_lambda_env_vars, {
-    EVENTPUB_SNS_TOPIC_ARN = "${module.eventpub.sns_topic.arn}"
+    EVENTPUB_SNS_TOPIC_ARN = "${module.eventpub.sns_topic.arn}",
+    EVENT_SOURCE = "/data-plane/supplier-api/${var.group}/${var.environment}/letters"
   })
 }
 
diff --git a/internal/events/package.json b/internal/events/package.json
index 04fcac176..08abc7453 100644
--- a/internal/events/package.json
+++ b/internal/events/package.json
@@ -50,5 +50,5 @@
     "typecheck": "tsc --noEmit"
   },
   "types": "dist/index.d.ts",
-  "version": "1.0.8"
+  "version": "1.0.9"
 }
diff --git a/internal/events/schemas/examples/letter.ACCEPTED.json b/internal/events/schemas/examples/letter.ACCEPTED.json
index c6533b93b..77a66c5b2 100644
--- a/internal/events/schemas/examples/letter.ACCEPTED.json
+++ b/internal/events/schemas/examples/letter.ACCEPTED.json
@@ -18,7 +18,7 @@
   "recordedtime": "2025-08-28T08:45:00.000Z",
   "severitynumber": 2,
   "severitytext": "INFO",
-  "source": "/data-plane/supplier-api/prod/update-status",
+  "source": "/data-plane/supplier-api/nhs-supplier-api-prod/main/update-status",
   "specversion": "1.0",
   "subject": "letter-origin/letter-rendering/letter/f47ac10b-58cc-4372-a567-0e02b2c3d479",
   "time": "2025-08-28T08:45:00.000Z",
diff --git a/internal/events/schemas/examples/letter.FORWARDED.json b/internal/events/schemas/examples/letter.FORWARDED.json
index 6661fe6c1..cd5bd1731 100644
--- a/internal/events/schemas/examples/letter.FORWARDED.json
+++ b/internal/events/schemas/examples/letter.FORWARDED.json
@@ -20,7 +20,7 @@
   "recordedtime": "2025-08-28T08:45:00.000Z",
   "severitynumber": 2,
   "severitytext": "INFO",
-  "source": "/data-plane/supplier-api/prod/update-status",
+  "source": "/data-plane/supplier-api/nhs-supplier-api-prod/main/update-status",
   "specversion": "1.0",
   "subject": "letter-origin/letter-rendering/letter/f47ac10b-58cc-4372-a567-0e02b2c3d479",
   "time": "2025-08-28T08:45:00.000Z",
diff --git a/internal/events/schemas/examples/letter.RETURNED.json b/internal/events/schemas/examples/letter.RETURNED.json
index f0cfa3761..1f54aea5a 100644
--- a/internal/events/schemas/examples/letter.RETURNED.json
+++ b/internal/events/schemas/examples/letter.RETURNED.json
@@ -20,7 +20,7 @@
   "recordedtime": "2025-08-28T08:45:00.000Z",
   "severitynumber": 2,
   "severitytext": "INFO",
-  "source": "/data-plane/supplier-api/prod/update-status",
+  "source": "/data-plane/supplier-api/nhs-supplier-api-prod/main/update-status",
   "specversion": "1.0",
   "subject": "letter-origin/letter-rendering/letter/f47ac10b-58cc-4372-a567-0e02b2c3d479",
   "time": "2025-08-28T08:45:00.000Z",
diff --git a/lambdas/letter-updates-transformer/src/__tests__/letter-updates-transformer.test.ts b/lambdas/letter-updates-transformer/src/__tests__/letter-updates-transformer.test.ts
index 67211462e..065a9a1e3 100644
--- a/lambdas/letter-updates-transformer/src/__tests__/letter-updates-transformer.test.ts
+++ b/lambdas/letter-updates-transformer/src/__tests__/letter-updates-transformer.test.ts
@@ -26,15 +26,18 @@ jest.mock("crypto", () => ({
   randomBytes: (size: number) => randomBytes[String(size)],
 }));
 
-describe("letter-updates-transformer Lambda", () => {
-  const mockedDeps: jest.Mocked<Deps> = {
-    snsClient: { send: jest.fn() } as unknown as SNSClient,
-    logger: { info: jest.fn(), error: jest.fn() } as unknown as pino.Logger,
-    env: {
-      EVENTPUB_SNS_TOPIC_ARN: "arn:aws:sns:region:account:topic",
-    } as unknown as EnvVars,
-  } as Deps;
+const eventSource =
+  "/data-plane/supplier-api/nhs-supplier-api-dev/main/letters";
+const mockedDeps: jest.Mocked<Deps> = {
+  snsClient: { send: jest.fn() } as unknown as SNSClient,
+  logger: { info: jest.fn(), error: jest.fn() } as unknown as pino.Logger,
+  env: {
+    EVENTPUB_SNS_TOPIC_ARN: "arn:aws:sns:region:account:topic",
+    EVENT_SOURCE: eventSource,
+  } as unknown as EnvVars,
+} as Deps;
 
+describe("letter-updates-transformer Lambda", () => {
   beforeEach(() => {
     jest.useFakeTimers();
   });
@@ -50,7 +53,9 @@ describe("letter-updates-transformer Lambda", () => {
       const newLetter = generateLetter("PRINTED");
       const expectedEntries = [
         expect.objectContaining({
-          Message: JSON.stringify(mapLetterToCloudEvent(newLetter)),
+          Message: JSON.stringify(
+            mapLetterToCloudEvent(newLetter, eventSource),
+          ),
         }),
       ];
 
@@ -76,7 +81,9 @@ describe("letter-updates-transformer Lambda", () => {
       newLetter.reasonCode = "R1";
       const expectedEntries = [
         expect.objectContaining({
-          Message: JSON.stringify(mapLetterToCloudEvent(newLetter)),
+          Message: JSON.stringify(
+            mapLetterToCloudEvent(newLetter, eventSource),
+          ),
         }),
       ];
 
@@ -103,7 +110,9 @@ describe("letter-updates-transformer Lambda", () => {
       newLetter.reasonCode = "R2";
       const expectedEntries = [
         expect.objectContaining({
-          Message: JSON.stringify(mapLetterToCloudEvent(newLetter)),
+          Message: JSON.stringify(
+            mapLetterToCloudEvent(newLetter, eventSource),
+          ),
         }),
       ];
 
@@ -135,14 +144,28 @@ describe("letter-updates-transformer Lambda", () => {
       expect(mockedDeps.snsClient.send).not.toHaveBeenCalled();
     });
 
-    it("does not publish non-modify events", async () => {
+    it("publishes INSERT events", async () => {
       const handler = createHandler(mockedDeps);
       const newLetter = generateLetter("ACCEPTED");
+      const expectedEntries = [
+        expect.objectContaining({
+          Message: JSON.stringify(
+            mapLetterToCloudEvent(newLetter, eventSource),
+          ),
+        }),
+      ];
 
       const testData = generateKinesisEvent([generateInsertRecord(newLetter)]);
       await handler(testData, mockDeep<Context>(), jest.fn());
 
-      expect(mockedDeps.snsClient.send).not.toHaveBeenCalled();
+      expect(mockedDeps.snsClient.send).toHaveBeenCalledWith(
+        expect.objectContaining({
+          input: expect.objectContaining({
+            TopicArn: "arn:aws:sns:region:account:topic",
+            PublishBatchRequestEntries: expectedEntries,
+          }),
+        }),
+      );
     });
 
     it("does not publish invalid letter data", async () => {
@@ -159,6 +182,55 @@ describe("letter-updates-transformer Lambda", () => {
 
       expect(mockedDeps.snsClient.send).not.toHaveBeenCalled();
     });
+
+    it("throws error when kinesis data contains malformed JSON", async () => {
+      const handler = createHandler(mockedDeps);
+
+      // Create a Kinesis event with malformed JSON data
+      const malformedKinesisEvent: KinesisStreamEvent = {
+        Records: [
+          {
+            kinesis: {
+              data: Buffer.from("invalid-json-data").toString("base64"),
+              sequenceNumber: "12345",
+            },
+          } as any,
+        ],
+      };
+
+      await expect(
+        handler(malformedKinesisEvent, mockDeep<Context>(), jest.fn()),
+      ).rejects.toThrow();
+
+      expect(mockedDeps.logger.error).toHaveBeenCalledWith(
+        expect.objectContaining({
+          description: "Error extracting payload",
+          error: expect.any(Error),
+          record: expect.objectContaining({
+            kinesis: expect.objectContaining({
+              data: Buffer.from("invalid-json-data").toString("base64"),
+            }),
+          }),
+        }),
+      );
+    });
+
+    it("handles events with no records", async () => {
+      const handler = createHandler(mockedDeps);
+
+      // Create a Kinesis event with empty Records array
+      const emptyKinesisEvent: KinesisStreamEvent = { Records: [] };
+
+      await handler(emptyKinesisEvent, mockDeep<Context>(), jest.fn());
+
+      expect(mockedDeps.logger.info).toHaveBeenCalledWith(
+        expect.objectContaining({
+          description: "Number of records",
+          count: 0,
+        }),
+      );
+      expect(mockedDeps.snsClient.send).not.toHaveBeenCalled();
+    });
   });
 
   describe("Batching", () => {
@@ -168,7 +240,7 @@ describe("letter-updates-transformer Lambda", () => {
       const newLetters = generateLetters(10, "PRINTED");
       const expectedEntries = newLetters.map((letter) =>
         expect.objectContaining({
-          Message: JSON.stringify(mapLetterToCloudEvent(letter)),
+          Message: JSON.stringify(mapLetterToCloudEvent(letter, eventSource)),
         }),
       );
 
@@ -197,19 +269,19 @@ describe("letter-updates-transformer Lambda", () => {
         newLetters.slice(0, 10).map((letter, index) =>
           expect.objectContaining({
             Id: expect.stringMatching(new RegExp(`-${index}$`)),
-            Message: JSON.stringify(mapLetterToCloudEvent(letter)),
+            Message: JSON.stringify(mapLetterToCloudEvent(letter, eventSource)),
           }),
         ),
         newLetters.slice(10, 20).map((letter, index) =>
           expect.objectContaining({
             Id: expect.stringMatching(new RegExp(`-${index}$`)),
-            Message: JSON.stringify(mapLetterToCloudEvent(letter)),
+            Message: JSON.stringify(mapLetterToCloudEvent(letter, eventSource)),
           }),
         ),
         newLetters.slice(20).map((letter, index) =>
           expect.objectContaining({
             Id: expect.stringMatching(new RegExp(`-${index}$`)),
-            Message: JSON.stringify(mapLetterToCloudEvent(letter)),
+            Message: JSON.stringify(mapLetterToCloudEvent(letter, eventSource)),
           }),
         ),
       ];
diff --git a/lambdas/letter-updates-transformer/src/env.ts b/lambdas/letter-updates-transformer/src/env.ts
index f93bbf39f..a91381864 100644
--- a/lambdas/letter-updates-transformer/src/env.ts
+++ b/lambdas/letter-updates-transformer/src/env.ts
@@ -2,6 +2,7 @@ import { z } from "zod";
 
 const EnvVarsSchema = z.object({
   EVENTPUB_SNS_TOPIC_ARN: z.string(),
+  EVENT_SOURCE: z.string(),
 });
 
 export type EnvVars = z.infer<typeof EnvVarsSchema>;
diff --git a/lambdas/letter-updates-transformer/src/letter-updates-transformer.ts b/lambdas/letter-updates-transformer/src/letter-updates-transformer.ts
index 85c6d2c94..c53151c07 100644
--- a/lambdas/letter-updates-transformer/src/letter-updates-transformer.ts
+++ b/lambdas/letter-updates-transformer/src/letter-updates-transformer.ts
@@ -20,17 +20,20 @@ const BATCH_SIZE = 10;
 export default function createHandler(deps: Deps): Handler<KinesisStreamEvent> {
   return async (streamEvent: KinesisStreamEvent) => {
     deps.logger.info({ description: "Received event", streamEvent });
+    deps.logger.info({
+      description: "Number of records",
+      count: streamEvent.Records?.length || 0,
+    });
 
-    const cloudEvents: LetterEvent[] = streamEvent.Records.map((record) =>
+    // Ensure logging by extracting all records first
+    const ddbRecords: DynamoDBRecord[] = streamEvent.Records.map((record) =>
       extractPayload(record, deps),
-    )
-      .filter((record) => record.eventName === "MODIFY")
-      .filter(
-        (record) =>
-          isChanged(record, "status") || isChanged(record, "reasonCode"),
-      )
+    );
+
+    const cloudEvents: LetterEvent[] = ddbRecords
+      .filter((record) => filterRecord(record, deps))
       .map((element) => extractNewLetter(element))
-      .map((element) => mapLetterToCloudEvent(element));
+      .map((element) => mapLetterToCloudEvent(element, deps.env.EVENT_SOURCE));
 
     for (const batch of generateBatches(cloudEvents)) {
       deps.logger.info({
@@ -50,14 +53,54 @@ export default function createHandler(deps: Deps): Handler<KinesisStreamEvent> {
   };
 }
 
+function filterRecord(record: DynamoDBRecord, deps: Deps): boolean {
+  let allowEvent = false;
+  if (record.eventName === "INSERT") {
+    allowEvent = true;
+  }
+
+  if (
+    record.eventName === "MODIFY" &&
+    (isChanged(record, "status") || isChanged(record, "reasonCode"))
+  ) {
+    allowEvent = true;
+  }
+
+  deps.logger.info({
+    description: "Filtering record",
+    eventName: record.eventName,
+    eventId: record.eventID,
+    allowEvent,
+  });
+
+  return allowEvent;
+}
+
 function extractPayload(
   record: KinesisStreamRecord,
   deps: Deps,
 ): DynamoDBRecord {
-  // Kinesis data is base64 encoded
-  const payload = Buffer.from(record.kinesis.data, "base64").toString("utf8");
-  deps.logger.info({ description: "Extracted dynamoDBRecord", payload });
-  return JSON.parse(payload);
+  try {
+    deps.logger.info({
+      description: "Processing Kinesis record",
+      recordId: record.kinesis.sequenceNumber,
+    });
+
+    // Kinesis data is base64 encoded
+    const payload = Buffer.from(record.kinesis.data, "base64").toString("utf8");
+    deps.logger.info({ description: "Decoded payload", payload });
+
+    const jsonParsed = JSON.parse(payload);
+    deps.logger.info({ description: "Extracted dynamoDBRecord", jsonParsed });
+    return jsonParsed;
+  } catch (error) {
+    deps.logger.error({
+      description: "Error extracting payload",
+      error,
+      record,
+    });
+    throw error;
+  }
 }
 
 function isChanged(record: DynamoDBRecord, property: string): boolean {
diff --git a/lambdas/letter-updates-transformer/src/mappers/__tests__/letter-mapper.test.ts b/lambdas/letter-updates-transformer/src/mappers/__tests__/letter-mapper.test.ts
index d36f52b40..ba91099c4 100644
--- a/lambdas/letter-updates-transformer/src/mappers/__tests__/letter-mapper.test.ts
+++ b/lambdas/letter-updates-transformer/src/mappers/__tests__/letter-mapper.test.ts
@@ -17,7 +17,8 @@ describe("letter-mapper", () => {
       source: "letter-rendering/source/test",
       subject: "letter-rendering/source/letter/letter-id",
     } as Letter;
-    const event = mapLetterToCloudEvent(letter);
+    const source = "/data-plane/supplier-api/nhs-supplier-api-dev/main/letters";
+    const event = mapLetterToCloudEvent(letter, source);
 
     // Check it conforms to the letter event schema - parse will throw an error if not
     $LetterEvent.parse(event);
@@ -25,7 +26,7 @@ describe("letter-mapper", () => {
     expect(event.dataschema).toBe(
       `https://notify.nhs.uk/cloudevents/schemas/supplier-api/letter.PRINTED.${event.dataschemaversion}.schema.json`,
     );
-    expect(event.dataschemaversion).toBe("1.0.8");
+    expect(event.dataschemaversion).toMatch(/1\.\d+\.\d+/);
     expect(event.subject).toBe("letter-origin/supplier-api/letter/id1");
     expect(event.time).toBe("2025-11-24T15:55:18.000Z");
     expect(event.recordedtime).toBe("2025-11-24T15:55:18.000Z");
@@ -45,5 +46,6 @@ describe("letter-mapper", () => {
         event: event.id,
       },
     });
+    expect(event.source).toBe(source);
   });
 });
diff --git a/lambdas/letter-updates-transformer/src/mappers/letter-mapper.ts b/lambdas/letter-updates-transformer/src/mappers/letter-mapper.ts
index 34cd23c56..468d9ffd6 100644
--- a/lambdas/letter-updates-transformer/src/mappers/letter-mapper.ts
+++ b/lambdas/letter-updates-transformer/src/mappers/letter-mapper.ts
@@ -5,6 +5,7 @@ import { LetterForEventPub } from "../types";
 
 export default function mapLetterToCloudEvent(
   letter: LetterForEventPub,
+  source: string,
 ): LetterEvent {
   const eventId = randomUUID();
   const dataschemaversion = eventSchemaPackage.version;
@@ -15,7 +16,7 @@ export default function mapLetterToCloudEvent(
     plane: "data",
     dataschema: `https://notify.nhs.uk/cloudevents/schemas/supplier-api/letter.${letter.status}.${dataschemaversion}.schema.json`,
     dataschemaversion,
-    source: "/data-plane/supplier-api/letters",
+    source,
     subject: `letter-origin/supplier-api/letter/${letter.id}`,
 
     data: {
diff --git a/package-lock.json b/package-lock.json
index baee66ec3..61aace1fc 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -123,7 +123,7 @@
     },
     "internal/events": {
       "name": "@nhsdigital/nhs-notify-event-schemas-supplier-api",
-      "version": "1.0.8",
+      "version": "1.0.9",
       "license": "MIT",
       "dependencies": {
         "@asyncapi/bundler": "^0.6.4",
diff --git a/pact-contracts/package.json b/pact-contracts/package.json
index c28d516d7..f97c4569f 100644
--- a/pact-contracts/package.json
+++ b/pact-contracts/package.json
@@ -1,25 +1,26 @@
 {
-  "name": "@nhsdigital/notify-supplier-api-consumer-contracts",
-  "version": "1.0.1",
   "description": "NHS Notify Supplier API Pact contracts",
-  "license": "MIT",
-  "repository": {
-    "type": "git",
-    "url": "git+ssh://git@github.com/NHSDigital/nhs-notify-supplier-api.git"
-  },
   "exports": {
     "./pacts/*.json": {
       "default": "./pacts/*.json"
     }
   },
+  "license": "MIT",
+  "name": "@nhsdigital/notify-supplier-api-consumer-contracts",
   "publishConfig": {
     "access": "public",
     "registry": "https://npm.pkg.github.com"
   },
+  "repository": {
+    "type": "git",
+    "url": "git+ssh://git@github.com/NHSDigital/nhs-notify-supplier-api.git"
+  },
   "scripts": {
     "lint": "echo Linting not required",
+    "lint:fix": "echo Linting not required",
     "test:unit": "echo Unit tests not required",
     "test:unit:coverage": "echo Unit tests not required",
     "typecheck": "echo Typecheck not required"
-  }
+  },
+  "version": "1.0.1"
 }