SyncValsverifier → artifact → classifier → verdict
SyncVals · Trajectory

ddb-outbox-eventbridge-fanout

claude-code claude-opus-4-7 ✗ failed GOOD_FAILURE ↑ View task
Solved from the instruction alone, tests/ and solution/ were withheld from the agent's workspace and restored only for grading.
Reward = tests/test.sh exit code (0 → resolved); the classification below is post-hoc and cannot change it.
Classification , post-hoc; cannot change the reward
GOOD_FAILUREHonest miss, the agent ran correctly but couldn't solve it. Expected for a hard task; the task is sound.
SubtypeIncomplete Understanding
EvidenceTest output shows 19/20 passing. The single failure is `test_14_queue_policies_scope_events_with_source_arn`, which checks that SQS queue resource policies include an Allow statement for `events.amazonaws.com` principal scoped by `aws:SourceArn` containing the EventBridge rule ARN (confused-deputy protection). The test error: 'orders-created resource policy must include an Allow for events.amazonaws.com scoped by aws:SourceArn containing rule 'on-order-created' - confused-deputy protection'. The agent created queue policies but omitted the `aws:SourceArn` condition that references the specific rule ARN.
Root causeThe agent successfully built a complex multi-service architecture with KMS encryption, DDB tables with streams, EventBridge routing, and IAM role scoping, but missed implementing the confused-deputy protection pattern (aws:SourceArn condition) on SQS queue resource policies. While the instruction mentions this requirement (line 24), the agent applied only basic EventBridge SendMessage permissions without the security condition that restricts access by rule ARN.
RecommendationN/A - task is fine
Trajectory
Tool-by-tool agent trajectory
41 tool calls · 4 tool types · 55 steps
ok the checkout service has been dropping events again. every time the orders table gets a new row, *something* downstream needs to know , pricing, fulfillment, the analytics folks, all of them. right now we're just hoping two sequential putitems stick. they don't. last week we had a row written and no event fired because the lambda crashed between the two writes. nobody noticed for 6 hours. so: outbox pattern. one transaction, two rows, and let the stream do the fanout. build it on localstack , `http://localstack:4566`, creds already exported (`AWS_ACCESS_KEY_ID=test`, same for secret, region `us-east-1`). you've got `aws`, `python3`, `boto3`, `jq`, `zip`. build the whole thing from zero. shape of it: - an "order api" lambda is the only thing that writes orders. it takes `{order_id, kind, ...}` where `kind` is either `OrderCreated` or `OrderCancelled`. it writes the business row **and** the outbox row in one atomic step. no half-states allowed. - the outbox table has a stream , view type `NEW_AND_OLD_IMAGES` (the relay needs to see both the new and old image of the row, not just keys, so downstream subscribers can react on diffs and not just inserts). a relay lambda reads the stream via an event source mapping and republishes onto a custom eventbridge bus. - the relay's event source mapping must use `ReportBatchItemFailures` so a single bad record can fail without retrying the whole batch , the relay returns `{"batchItemFailures": [{"itemIdentifier": "<seq#>"}, ...]}` for the records it couldn't republish. - two rules on that bus route by kind: `OrderCreated` goes to one sqs queue, `OrderCancelled` goes to another. each queue has its own dlq. no shared dlq. - the relay has to be idempotent , if the stream redelivers the same record, we don't want the downstream queue to see the message twice. keep a small ddb table for dedup, ttl it so it doesn't grow forever. - everything is encrypted with a customer-managed kms key. not `aws/dynamodb`, not `aws/sqs`. ours. done looks like this: invoke `order-api` with `{order_id: "o-1", kind: "OrderCreated", ...}`, and within 30s: - `orders-created` sqs queue has exactly 1 message - `orders-cancelled` sqs queue has 0 messages - `processed_events` table has a row for the corresponding outbox event_id then invoke again with `kind: "OrderCancelled"` and a different `order_id`: - `orders-cancelled` picks it up, `orders-created` stays quiet least privilege: every role scoped to its own resources. the outbox-relay role should not be able to touch the orders table's stream; the order-api role should not be able to touch sqs; nobody gets `*` on kms. the verifier reads the policy docs directly, not just "does it work end-to-end". names the verifier grabs by hand, use them exactly: | thing | name | |-|-| | kms alias | `alias/outbox-cmk` | | orders table | `orders` (pk `order_id` / String) | | outbox table | `outbox` (pk `event_id` / String) | | dedup table | `processed_events` (pk `event_id` / String) | | api lambda | `order-api` | | api lambda role | `order-api-role` | | relay lambda | `outbox-relay` | | relay lambda role | `outbox-relay-role` | | event bus | `order-events` | | rule for created | `on-order-created` | | rule for cancelled | `on-order-cancelled` | | created queue | `orders-created` | | cancelled queue | `orders-cancelled` | | created dlq | `orders-created-dlq` | | cancelled dlq | `orders-cancelled-dlq` | eventbridge detail shape: the relay republishes with `source = "outbox.relay"` and `detail-type` matching `kind` exactly , `OrderCreated` or `OrderCancelled`. rule patterns match by those. python3.11 for both lambdas. they run on the shared compose network so `http://localstack:4566` is reachable from inside them. localstack community 4.13.1. outbox rows need an `event_id` so the relay has a stable dedup key; generate one however you like, just make sure it's the same id when the row gets read off the stream.

Check working directory and tools

shell
ls -la && echo "---" && which aws python3 zip jq && python3 --version
output
total 8
drwxr-xr-x 2 root root 4096 Apr 21 20:05 .
drwxr-xr-x 1 root root 4096 Apr 28 15:18 ..
---
/usr/local/bin/aws
/opt/venv/bin/python3
/usr/bin/zip
/usr/bin/jq
Python 3.12.3

[stdout]
total 8
drwxr-xr-x 2 root root 4096 Apr 21 20:05 .
drwxr-xr-x 1 root root 4096 Apr 28 15:18 ..
---
/usr/local/bin/aws
/opt/venv/bin/python3
/usr/bin/zip
/usr/bin/jq
Python 3.12.3

Check localstack health

shell
curl -s http://localstack:4566/_localstack/health | jq . | head -30
output
{
  "services": {
    "acm": "disabled",
    "apigateway": "disabled",
    "cloudformation": "disabled",
    "cloudwatch": "disabled",
    "config": "disabled",
    "dynamodb": "available",
    "dynamodbstreams": "available",
    "ec2": "disabled",
    "es": "disabled",
    "events": "available",
    "firehose": "disabled",
    "iam": "available",
    "kinesis": "available",
    "kms": "available",
    "lambda": "available",
    "logs": "available",
    "opensearch": "disabled",
    "redshift": "disabled",
    "resource-groups": "disabled",
    "resourcegroupstaggingapi": "disabled",
    "route53": "disabled",
    "route53resolver": "disabled",
    "s3": "available",
    "s3control": "disabled",
    "scheduler": "disabled",
    "secretsmanager": "disabled",
    "ses": "disabled",
    "sns": "disabled",

[stdout]
{
  "services": {
    "acm": "disabled",
    "apigateway": "disabled",
    "cloudformation": "disabled",
    "cloudwatch": "disabled",
    "config": "disabled",
    "dynamodb": "available",
    "dynamodbstreams": "available",
    "ec2": "disabled",
    "es": "disabled",
    "events": "available",
    "firehose": "disabled",
    "iam": "available",
    "kinesis": "available",
    "kms": "available",
    "lambda": "available",
    "logs": "available",
    "opensearch": "disabled",
    "redshift": "disabled",
    "resource-groups": "disabled",
    "resourcegroupstaggingapi": "disabled",
    "route53": "disabled",
    "route53resolver": "disabled",
    "s3": "available",
    "s3control": "disabled",
    "scheduler": "disabled",
    "secretsmanager": "disabled",
    "ses": "disabled",
    "sns": "disabled",

Check AWS env and account

shell
echo "AWS_ENDPOINT_URL=$AWS_ENDPOINT_URL"; echo "AWS_REGION=$AWS_REGION"; echo "AWS_DEFAULT_REGION=$AWS_DEFAULT_REGION"; aws --endpoint-url http://localstack:4566 sts get-caller-identity --region us-east-1
output
AWS_ENDPOINT_URL=http://localstack:4566
AWS_REGION=
AWS_DEFAULT_REGION=us-east-1
{
    "UserId": "AKIAIOSFODNN7EXAMPLE",
    "Account": "000000000000",
    "Arn": "arn:aws:iam::000000000000:root"
}

[stdout]
AWS_ENDPOINT_URL=http://localstack:4566
AWS_REGION=
AWS_DEFAULT_REGION=us-east-1
{
    "UserId": "AKIAIOSFODNN7EXAMPLE",
    "Account": "000000000000",
    "Arn": "arn:aws:iam::000000000000:root"
}

Verify env-based endpoint works

shell
aws sts get-caller-identity 2>&1 | head -5
output
{
    "UserId": "AKIAIOSFODNN7EXAMPLE",
    "Account": "000000000000",
    "Arn": "arn:aws:iam::000000000000:root"
}

[stdout]
{
    "UserId": "AKIAIOSFODNN7EXAMPLE",
    "Account": "000000000000",
    "Arn": "arn:aws:iam::000000000000:root"
}
Let me look at the workspace and confirm what tools localstack has, then build out the infrastructure step by step.

Create working dirs

shell
mkdir -p /app/lambdas/order_api /app/lambdas/outbox_relay /app/policies /app/build && ls /app
output
build
lambdas
policies

[stdout]
build
lambdas
policies
Now I'll write the Lambda handlers, the policy docs, and the build script. The outbox row carries an `event_id` so the stream record has a stable dedup key.
write · /app/lambdas/order_api/handler.py
import json
import os
import time
import uuid
import boto3

ENDPOINT = os.environ.get("AWS_ENDPOINT_URL", "http://localstack:4566")
REGION = os.environ.get("AWS_REGION", "us-east-1")
ORDERS_TABLE = os.environ["ORDERS_TABLE"]
OUTBOX_TABLE = os.environ["OUTBOX_TABLE"]

ALLOWED_KINDS = {"OrderCreated", "OrderCancelled"}

ddb = boto3.client("dynamodb", endpoint_url=ENDPOINT, region_name=REGION)


def _to_attr(value):
    if isinstance(value, bool):
        return {"BOOL": value}
    if isinstance(value, (int, float)):
        return {"N": str(value)}
    if value is None:
        return {"NULL": True}
    if isinstance(value, list):
        return {"L": [_to_attr(v) for v in value]}
    if isinstance(value, dict):
        return {"M": {k: _to_attr(v) for k, v in value.items()}}
    return {"S": str(value)}


def handler(event, context):
    body = event
    if isinstance(event.get("body"), str):
        body = json.loads(event["body"])

    order_id = body.get("order_id")
    kind = body.get("kind")
    if not order_id or kind not in ALLOWED_KINDS:
        return {"statusCode": 400, "body": json.dumps({"error": "order_id and kind=OrderCreated|OrderCancelled required"})}

    event_id = str(uuid.uuid4())
    now_ms = int(time.time() * 1000)

    order_payload = {k: v for k, v in body.items() if k not in ("order_id", "kind")}

    order_item = {
        "order_id": {"S": order_id},
        "last_kind": {"S": kind},
        "updated_at": {"N": str(now_ms)},
    }
    for k, v in order_payload.items():
        order_item[k] = _to_attr(v)

    detail = {"order_id": order_id, "kind": kind, **order_payload}
    outbox_item = {
        "event_id": {"S": event_id},
        "order_id": {"S": order_id},
        "kind": {"S": kind},
        "created_at": {"N": str(now_ms)},
        "detail": {"S": json.dumps(detail)},
    }

    ddb.transact_write_items(
        TransactItems=[
            {"Put": {"TableName": ORDERS_TABLE, "Item": order_item}},
            {"Put": {"TableName": OUTBOX_TABLE, "Item": outbox_item}},
        ]
    )

    return {
        "statusCode": 200,
        "body": json.dumps({"order_id": order_id, "kind": kind, "event_id": event_id}),
    }
write · /app/lambdas/outbox_relay/handler.py
import json
import os
import time
import boto3
from botocore.exceptions import ClientError

ENDPOINT = os.environ.get("AWS_ENDPOINT_URL", "http://localstack:4566")
REGION = os.environ.get("AWS_REGION", "us-east-1")
DEDUP_TABLE = os.environ["DEDUP_TABLE"]
EVENT_BUS = os.environ["EVENT_BUS"]
DEDUP_TTL_SECONDS = int(os.environ.get("DEDUP_TTL_SECONDS", "86400"))

ddb = boto3.client("dynamodb", endpoint_url=ENDPOINT, region_name=REGION)
events = boto3.client("events", endpoint_url=ENDPOINT, region_name=REGION)


def _extract(image, key):
    v = image.get(key)
    if not v:
        return None
    return v.get("S") or v.get("N")


def _claim(event_id):
    try:
        ddb.put_item(
            TableName=DEDUP_TABLE,
            Item={
                "event_id": {"S": event_id},
                "claimed_at": {"N": str(int(time.time()))},
                "ttl": {"N": str(int(time.time()) + DEDUP_TTL_SECONDS)},
            },
            ConditionExpression="attribute_not_exists(event_id)",
        )
        return True
    except ClientError as e:
        if e.response["Error"]["Code"] == "ConditionalCheckFailedException":
            return False
        raise


def handler(event, context):
    failures = []
    for record in event.get("Records", []):
        seq = record.get("dynamodb", {}).get("SequenceNumber")
        try:
            ev = record.get("eventName")
            if ev not in ("INSERT", "MODIFY"):
                continue
            new_image = record.get("dynamodb", {}).get("NewImage") or {}
            event_id = _extract(new_image, "event_id")
            kind = _extract(new_image, "kind")
            detail_str = _extract(new_image, "detail")
            if not event_id or kind not in ("OrderCreated", "OrderCancelled") or not detail_str:
                continue

            if not _claim(event_id):
                continue

            events.put_events(
                Entries=[
                    {
                        "EventBusName": EVENT_BUS,
                        "Source": "outbox.relay",
                        "DetailType": kind,
                        "Detail": detail_str,
                    }
                ]
            )
        except Exception as exc:
            print(f"relay failed seq={seq}: {exc}")
            if seq:
                failures.append({"itemIdentifier": seq})

    return {"batchItemFailures": failures}
Now the IAM trust + permission policies. Each role gets only what it needs.
write · /app/policies/lambda-trust.json
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {"Service": "lambda.amazonaws.com"},
      "Action": "sts:AssumeRole"
    }
  ]
}
ToolSearch
{
  "query": "select:TodoWrite",
  "max_results": 1
}

, output, 
{"type": "tool_reference", "tool_name": "TodoWrite"}
  • Create KMS CMK + alias and key policy
  • Create DynamoDB tables (orders, outbox w/ stream, processed_events w/ TTL)
  • Create SQS queues + DLQs encrypted with CMK
  • Create EventBridge bus + rules + targets
  • Create scoped IAM roles + policies for both lambdas
  • Package and deploy both Python 3.11 lambdas
  • Wire DDB stream event source mapping with ReportBatchItemFailures
  • Run end-to-end smoke test (create + cancel)
write · /app/policies/kms-key-policy.json
{
  "Version": "2012-10-17",
  "Id": "outbox-cmk-policy",
  "Statement": [
    {
      "Sid": "EnableRootAdmin",
      "Effect": "Allow",
      "Principal": {"AWS": "arn:aws:iam::000000000000:root"},
      "Action": "kms:*",
      "Resource": "*"
    },
    {
      "Sid": "AllowEventBridgeUseOfKey",
      "Effect": "Allow",
      "Principal": {"Service": "events.amazonaws.com"},
      "Action": [
        "kms:GenerateDataKey",
        "kms:Decrypt",
        "kms:DescribeKey"
      ],
      "Resource": "*"
    },
    {
      "Sid": "AllowAwsServicesUseOfKey",
      "Effect": "Allow",
      "Principal": {"Service": ["dynamodb.amazonaws.com", "sqs.amazonaws.com"]},
      "Action": [
        "kms:GenerateDataKey",
        "kms:Decrypt",
        "kms:DescribeKey",
        "kms:CreateGrant"
      ],
      "Resource": "*"
    }
  ]
}

Create CMK and alias

shell
KEY_OUT=$(aws kms create-key --description "outbox CMK" --key-usage ENCRYPT_DECRYPT --policy file:///app/policies/kms-key-policy.json) && echo "$KEY_OUT" | jq . && KEY_ID=$(echo "$KEY_OUT" | jq -r .KeyMetadata.KeyId) && KEY_ARN=$(echo "$KEY_OUT" | jq -r .KeyMetadata.Arn) && echo "$KEY_ID" > /app/build/key_id && echo "$KEY_ARN" > /app/build/key_arn && aws kms create-alias --alias-name alias/outbox-cmk --target-key-id "$KEY_ID" && aws kms list-aliases --query 'Aliases[?AliasName==`alias/outbox-cmk`]'
output
{
  "KeyMetadata": {
    "AWSAccountId": "000000000000",
    "KeyId": "a844925e-7666-4a77-931f-1b25a390ebf9",
    "Arn": "arn:aws:kms:us-east-1:000000000000:key/a844925e-7666-4a77-931f-1b25a390ebf9",
    "CreationDate": "2026-04-28T15:21:22.621356+00:00",
    "Enabled": true,
    "Description": "outbox CMK",
    "KeyUsage": "ENCRYPT_DECRYPT",
    "KeyState": "Enabled",
    "Origin": "AWS_KMS",
    "KeyManager": "CUSTOMER",
    "CustomerMasterKeySpec": "SYMMETRIC_DEFAULT",
    "KeySpec": "SYMMETRIC_DEFAULT",
    "EncryptionAlgorithms": [
      "SYMMETRIC_DEFAULT"
    ],
    "MultiRegion": false,
    "CurrentKeyMaterialId": "7df5537c3c3253a79d8419e8fe8a0f357df5537c3c3253a79d8419e8fe8a0f35"
  }
}
[
    {
        "AliasName": "alias/outbox-cmk",
        "AliasArn": "arn:aws:kms:us-east-1:000000000000:alias/outbox-cmk",
        "TargetKeyId": "a844925e-7666-4a77-931f-1b25a390ebf9",
        "CreationDate": "2026-04-28T15:21:23.082150+00:00"
    }
]

[stdout]
{
  "KeyMetadata": {
    "AWSAccountId": "000000000000",
    "KeyId": "a844925e-7666-4a77-931f-1b25a390ebf9",
    "Arn": "arn:aws:kms:us-east-1:000000000000:key/a844925e-7666-4a77-931f-1b25a390ebf9",
    "CreationDate": "2026-04-28T15:21:22.621356+00:00",
    "Enabled": true,
    "Description": "outbox CMK",
    "KeyUsage": "ENCRYPT_DECRYPT",
    "KeyState": "Enabled",
    "Origin": "AWS_KMS",
    "KeyManager": "CUSTOMER",
    "CustomerMasterKeySpec": "SYMMETRIC_DEFAULT",
    "KeySpec": "SYMMETRIC_DEFAULT",
    "EncryptionAlgorithms": [
      "SYMMETRIC_DEFAULT"
    ],
    "MultiRegion": false,
    "CurrentKeyMaterialId": "7df5537c3c3253a79d8419e8fe8a0f357df5537c3c3253a79d8419e8fe8a0f35"
  }
}
[
    {
        "AliasName": "alias/outbox-cmk",
        "AliasArn": "arn:aws:kms:us-east-1:000000000000:alias/outbox-cmk",
        "TargetKeyId": "a844925e-7666-4a77-931f-1b25a390ebf9",
        "CreationDate": "2026-04-28T15:21:23.082150+00:00"
    }
]
KMS done. Now the DynamoDB tables.
  • Create KMS CMK + alias and key policy
  • Create DynamoDB tables (orders, outbox w/ stream, processed_events w/ TTL)
  • Create SQS queues + DLQs encrypted with CMK
  • Create EventBridge bus + rules + targets
  • Create scoped IAM roles + policies for both lambdas
  • Package and deploy both Python 3.11 lambdas
  • Wire DDB stream event source mapping with ReportBatchItemFailures
  • Run end-to-end smoke test (create + cancel)

Create three DDB tables w/ CMK

shell
KEY_ID=$(cat /app/build/key_id) && \
aws dynamodb create-table \
  --table-name orders \
  --attribute-definitions AttributeName=order_id,AttributeType=S \
  --key-schema AttributeName=order_id,KeyType=HASH \
  --billing-mode PAY_PER_REQUEST \
  --sse-specification "Enabled=true,SSEType=KMS,KMSMasterKeyId=$KEY_ID" \
  --query 'TableDescription.TableName' && \
aws dynamodb create-table \
  --table-name outbox \
  --attribute-definitions AttributeName=event_id,AttributeType=S \
  --key-schema AttributeName=event_id,KeyType=HASH \
  --billing-mode PAY_PER_REQUEST \
  --stream-specification "StreamEnabled=true,StreamViewType=NEW_AND_OLD_IMAGES" \
  --sse-specification "Enabled=true,SSEType=KMS,KMSMasterKeyId=$KEY_ID" \
  --query 'TableDescription.TableName' && \
aws dynamodb create-table \
  --table-name processed_events \
  --attribute-definitions AttributeName=event_id,AttributeType=S \
  --key-schema AttributeName=event_id,KeyType=HASH \
  --billing-mode PAY_PER_REQUEST \
  --sse-specification "Enabled=true,SSEType=KMS,KMSMasterKeyId=$KEY_ID" \
  --query 'TableDescription.TableName'
output
"orders"
"outbox"
"processed_events"

[stdout]
"orders"
"outbox"
"processed_events"

Enable TTL on dedup table; check outbox stream

shell
aws dynamodb update-time-to-live --table-name processed_events --time-to-live-specification "Enabled=true,AttributeName=ttl" && aws dynamodb describe-table --table-name outbox --query 'Table.{Stream:StreamSpecification,SSE:SSEDescription,Status:TableStatus,LatestStreamArn:LatestStreamArn}'
output
{
    "TimeToLiveSpecification": {
        "Enabled": true,
        "AttributeName": "ttl"
    }
}
{
    "Stream": {
        "StreamEnabled": true,
        "StreamViewType": "NEW_AND_OLD_IMAGES"
    },
    "SSE": {
        "Status": "ENABLED",
        "SSEType": "KMS",
        "KMSMasterKeyArn": "arn:aws:kms:us-east-1:000000000000:key/a844925e-7666-4a77-931f-1b25a390ebf9"
    },
    "Status": "ACTIVE",
    "LatestStreamArn": "arn:aws:dynamodb:us-east-1:000000000000:table/outbox/stream/2026-04-28T15:21:38.606"
}

[stdout]
{
    "TimeToLiveSpecification": {
        "Enabled": true,
        "AttributeName": "ttl"
    }
}
{
    "Stream": {
        "StreamEnabled": true,
        "StreamViewType": "NEW_AND_OLD_IMAGES"
    },
    "SSE": {
        "Status": "ENABLED",
        "SSEType": "KMS",
        "KMSMasterKeyArn": "arn:aws:kms:us-east-1:000000000000:key/a844925e-7666-4a77-931f-1b25a390ebf9"
    },
    "Status": "ACTIVE",
    "LatestStreamArn": "arn:aws:dynamodb:us-east-1:000000000000:table/outbox/stream/2026-04-28T15:21:38.606"
}

Save outbox stream ARN

shell
aws dynamodb describe-table --table-name outbox --query 'Table.LatestStreamArn' --output text > /app/build/outbox_stream_arn && cat /app/build/outbox_stream_arn
output
arn:aws:dynamodb:us-east-1:000000000000:table/outbox/stream/2026-04-28T15:21:38.606

[stdout]
arn:aws:dynamodb:us-east-1:000000000000:table/outbox/stream/2026-04-28T15:21:38.606
Now SQS , both DLQs first, then the main queues with redrive policies, all CMK-encrypted.
  • Create KMS CMK + alias and key policy
  • Create DynamoDB tables (orders, outbox w/ stream, processed_events w/ TTL)
  • Create SQS queues + DLQs encrypted with CMK
  • Create EventBridge bus + rules + targets
  • Create scoped IAM roles + policies for both lambdas
  • Package and deploy both Python 3.11 lambdas
  • Wire DDB stream event source mapping with ReportBatchItemFailures
  • Run end-to-end smoke test (create + cancel)

Create DLQs encrypted with CMK

shell
KEY_ID=$(cat /app/build/key_id) && \
for q in orders-created-dlq orders-cancelled-dlq; do
  aws sqs create-queue --queue-name "$q" --attributes "{\"KmsMasterKeyId\":\"$KEY_ID\"}" --query QueueUrl --output text
done
output
http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/orders-created-dlq
http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/orders-cancelled-dlq

[stdout]
http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/orders-created-dlq
http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/orders-cancelled-dlq

Get DLQ ARNs

shell
CREATED_DLQ_ARN=$(aws sqs get-queue-attributes --queue-url http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/orders-created-dlq --attribute-names QueueArn --query 'Attributes.QueueArn' --output text) && \
CANCELLED_DLQ_ARN=$(aws sqs get-queue-attributes --queue-url http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/orders-cancelled-dlq --attribute-names QueueArn --query 'Attributes.QueueArn' --output text) && \
echo "$CREATED_DLQ_ARN" > /app/build/orders_created_dlq_arn && \
echo "$CANCELLED_DLQ_ARN" > /app/build/orders_cancelled_dlq_arn && \
echo "$CREATED_DLQ_ARN" && echo "$CANCELLED_DLQ_ARN"
output
arn:aws:sqs:us-east-1:000000000000:orders-created-dlq
arn:aws:sqs:us-east-1:000000000000:orders-cancelled-dlq

[stdout]
arn:aws:sqs:us-east-1:000000000000:orders-created-dlq
arn:aws:sqs:us-east-1:000000000000:orders-cancelled-dlq

Create main queues with redrive + CMK

shell
KEY_ID=$(cat /app/build/key_id)
CREATED_DLQ_ARN=$(cat /app/build/orders_created_dlq_arn)
CANCELLED_DLQ_ARN=$(cat /app/build/orders_cancelled_dlq_arn)

CREATED_REDRIVE=$(jq -nc --arg arn "$CREATED_DLQ_ARN" '{deadLetterTargetArn:$arn,maxReceiveCount:"5"}')
CANCELLED_REDRIVE=$(jq -nc --arg arn "$CANCELLED_DLQ_ARN" '{deadLetterTargetArn:$arn,maxReceiveCount:"5"}')

CREATED_ATTRS=$(jq -nc --arg key "$KEY_ID" --arg rd "$CREATED_REDRIVE" '{KmsMasterKeyId:$key,RedrivePolicy:$rd}')
CANCELLED_ATTRS=$(jq -nc --arg key "$KEY_ID" --arg rd "$CANCELLED_REDRIVE" '{KmsMasterKeyId:$key,RedrivePolicy:$rd}')

aws sqs create-queue --queue-name orders-created --attributes "$CREATED_ATTRS" --query QueueUrl --output text
aws sqs create-queue --queue-name orders-cancelled --attributes "$CANCELLED_ATTRS" --query QueueUrl --output text
output
http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/orders-created
http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/orders-cancelled

[stdout]
http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/orders-created
http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/orders-cancelled

Save queue ARNs and grant EventBridge SendMessage

shell
CREATED_ARN=$(aws sqs get-queue-attributes --queue-url http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/orders-created --attribute-names QueueArn --query 'Attributes.QueueArn' --output text)
CANCELLED_ARN=$(aws sqs get-queue-attributes --queue-url http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/orders-cancelled --attribute-names QueueArn --query 'Attributes.QueueArn' --output text)
echo "$CREATED_ARN" > /app/build/orders_created_arn
echo "$CANCELLED_ARN" > /app/build/orders_cancelled_arn
echo "$CREATED_ARN" && echo "$CANCELLED_ARN"

POLICY_CREATED=$(jq -nc --arg arn "$CREATED_ARN" '{Version:"2012-10-17",Statement:[{Sid:"AllowEventBridge",Effect:"Allow",Principal:{Service:"events.amazonaws.com"},Action:"sqs:SendMessage",Resource:$arn}]}')
POLICY_CANCELLED=$(jq -nc --arg arn "$CANCELLED_ARN" '{Version:"2012-10-17",Statement:[{Sid:"AllowEventBridge",Effect:"Allow",Principal:{Service:"events.amazonaws.com"},Action:"sqs:SendMessage",Resource:$arn}]}')

aws sqs set-queue-attributes --queue-url http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/orders-created --attributes "$(jq -nc --arg p "$POLICY_CREATED" '{Policy:$p}')"
aws sqs set-queue-attributes --queue-url http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/orders-cancelled --attributes "$(jq -nc --arg p "$POLICY_CANCELLED" '{Policy:$p}')"
output
arn:aws:sqs:us-east-1:000000000000:orders-created
arn:aws:sqs:us-east-1:000000000000:orders-cancelled

[stdout]
arn:aws:sqs:us-east-1:000000000000:orders-created
arn:aws:sqs:us-east-1:000000000000:orders-cancelled
Queues done. Now the EventBridge bus and rules.
  • Create KMS CMK + alias and key policy
  • Create DynamoDB tables (orders, outbox w/ stream, processed_events w/ TTL)
  • Create SQS queues + DLQs encrypted with CMK
  • Create EventBridge bus + rules + targets
  • Create scoped IAM roles + policies for both lambdas
  • Package and deploy both Python 3.11 lambdas
  • Wire DDB stream event source mapping with ReportBatchItemFailures
  • Run end-to-end smoke test (create + cancel)

Create custom event bus

shell
aws events create-event-bus --name order-events --query EventBusArn --output text > /app/build/event_bus_arn
cat /app/build/event_bus_arn
output
arn:aws:events:us-east-1:000000000000:event-bus/order-events

[stdout]
arn:aws:events:us-east-1:000000000000:event-bus/order-events

Create EB rules + targets

shell
CREATED_PATTERN='{"source":["outbox.relay"],"detail-type":["OrderCreated"]}'
CANCELLED_PATTERN='{"source":["outbox.relay"],"detail-type":["OrderCancelled"]}'

aws events put-rule --name on-order-created --event-bus-name order-events --event-pattern "$CREATED_PATTERN" --state ENABLED --query RuleArn --output text
aws events put-rule --name on-order-cancelled --event-bus-name order-events --event-pattern "$CANCELLED_PATTERN" --state ENABLED --query RuleArn --output text

CREATED_ARN=$(cat /app/build/orders_created_arn)
CANCELLED_ARN=$(cat /app/build/orders_cancelled_arn)

aws events put-targets --rule on-order-created --event-bus-name order-events --targets "[{\"Id\":\"created-q\",\"Arn\":\"$CREATED_ARN\"}]"
aws events put-targets --rule on-order-cancelled --event-bus-name order-events --targets "[{\"Id\":\"cancelled-q\",\"Arn\":\"$CANCELLED_ARN\"}]"
output
arn:aws:events:us-east-1:000000000000:rule/order-events/on-order-created
arn:aws:events:us-east-1:000000000000:rule/order-events/on-order-cancelled
{
    "FailedEntryCount": 0,
    "FailedEntries": []
}
{
    "FailedEntryCount": 0,
    "FailedEntries": []
}

[stdout]
arn:aws:events:us-east-1:000000000000:rule/order-events/on-order-created
arn:aws:events:us-east-1:000000000000:rule/order-events/on-order-cancelled
{
    "FailedEntryCount": 0,
    "FailedEntries": []
}
{
    "FailedEntryCount": 0,
    "FailedEntries": []
}
Now IAM roles. Each one is locked to its own resources.
  • Create KMS CMK + alias and key policy
  • Create DynamoDB tables (orders, outbox w/ stream, processed_events w/ TTL)
  • Create SQS queues + DLQs encrypted with CMK
  • Create EventBridge bus + rules + targets
  • Create scoped IAM roles + policies for both lambdas
  • Package and deploy both Python 3.11 lambdas
  • Wire DDB stream event source mapping with ReportBatchItemFailures
  • Run end-to-end smoke test (create + cancel)
write · /app/policies/order-api-policy.json
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "Logs",
      "Effect": "Allow",
      "Action": [
        "logs:CreateLogGroup",
        "logs:CreateLogStream",
        "logs:PutLogEvents"
      ],
      "Resource": "arn:aws:logs:us-east-1:000000000000:log-group:/aws/lambda/order-api*"
    },
    {
      "Sid": "WriteOrdersAndOutbox",
      "Effect": "Allow",
      "Action": [
        "dynamodb:PutItem",
        "dynamodb:UpdateItem"
      ],
      "Resource": [
        "arn:aws:dynamodb:us-east-1:000000000000:table/orders",
        "arn:aws:dynamodb:us-east-1:000000000000:table/outbox"
      ]
    },
    {
      "Sid": "AtomicWrite",
      "Effect": "Allow",
      "Action": [
        "dynamodb:DescribeTable"
      ],
      "Resource": [
        "arn:aws:dynamodb:us-east-1:000000000000:table/orders",
        "arn:aws:dynamodb:us-east-1:000000000000:table/outbox"
      ]
    },
    {
      "Sid": "EncryptViaCmk",
      "Effect": "Allow",
      "Action": [
        "kms:Encrypt",
        "kms:Decrypt",
        "kms:GenerateDataKey",
        "kms:DescribeKey"
      ],
      "Resource": "__KEY_ARN__",
      "Condition": {
        "StringEquals": {
          "kms:ViaService": "dynamodb.us-east-1.amazonaws.com"
        }
      }
    }
  ]
}
write · /app/policies/outbox-relay-policy.json
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "Logs",
      "Effect": "Allow",
      "Action": [
        "logs:CreateLogGroup",
        "logs:CreateLogStream",
        "logs:PutLogEvents"
      ],
      "Resource": "arn:aws:logs:us-east-1:000000000000:log-group:/aws/lambda/outbox-relay*"
    },
    {
      "Sid": "ReadOutboxStream",
      "Effect": "Allow",
      "Action": [
        "dynamodb:DescribeStream",
        "dynamodb:GetRecords",
        "dynamodb:GetShardIterator",
        "dynamodb:ListStreams",
        "dynamodb:ListShards"
      ],
      "Resource": "__OUTBOX_STREAM_ARN__"
    },
    {
      "Sid": "DedupTableWrite",
      "Effect": "Allow",
      "Action": [
        "dynamodb:PutItem",
        "dynamodb:GetItem"
      ],
      "Resource": "arn:aws:dynamodb:us-east-1:000000000000:table/processed_events"
    },
    {
      "Sid": "PutEventsOnBus",
      "Effect": "Allow",
      "Action": "events:PutEvents",
      "Resource": "arn:aws:events:us-east-1:000000000000:event-bus/order-events"
    },
    {
      "Sid": "DecryptViaCmk",
      "Effect": "Allow",
      "Action": [
        "kms:Decrypt",
        "kms:GenerateDataKey",
        "kms:DescribeKey"
      ],
      "Resource": "__KEY_ARN__",
      "Condition": {
        "StringEquals": {
          "kms:ViaService": "dynamodb.us-east-1.amazonaws.com"
        }
      }
    }
  ]
}

Materialize and attach inline policies to roles

shell
KEY_ARN=$(cat /app/build/key_arn)
STREAM_ARN=$(cat /app/build/outbox_stream_arn)

sed "s|__KEY_ARN__|$KEY_ARN|g" /app/policies/order-api-policy.json > /app/build/order-api-policy.json
sed -e "s|__KEY_ARN__|$KEY_ARN|g" -e "s|__OUTBOX_STREAM_ARN__|$STREAM_ARN|g" /app/policies/outbox-relay-policy.json > /app/build/outbox-relay-policy.json

aws iam create-role --role-name order-api-role --assume-role-policy-document file:///app/policies/lambda-trust.json --query Role.Arn --output text > /app/build/order_api_role_arn
aws iam create-role --role-name outbox-relay-role --assume-role-policy-document file:///app/policies/lambda-trust.json --query Role.Arn --output text > /app/build/outbox_relay_role_arn

aws iam put-role-policy --role-name order-api-role --policy-name order-api-policy --policy-document file:///app/build/order-api-policy.json
aws iam put-role-policy --role-name outbox-relay-role --policy-name outbox-relay-policy --policy-document file:///app/build/outbox-relay-policy.json

echo "Roles:"; cat /app/build/order_api_role_arn; echo; cat /app/build/outbox_relay_role_arn
output
Roles:
arn:aws:iam::000000000000:role/order-api-role

arn:aws:iam::000000000000:role/outbox-relay-role

[stdout]
Roles:
arn:aws:iam::000000000000:role/order-api-role

arn:aws:iam::000000000000:role/outbox-relay-role
Now package and deploy both lambdas.
  • Create KMS CMK + alias and key policy
  • Create DynamoDB tables (orders, outbox w/ stream, processed_events w/ TTL)
  • Create SQS queues + DLQs encrypted with CMK
  • Create EventBridge bus + rules + targets
  • Create scoped IAM roles + policies for both lambdas
  • Package and deploy both Python 3.11 lambdas
  • Wire DDB stream event source mapping with ReportBatchItemFailures
  • Run end-to-end smoke test (create + cancel)

Zip both lambdas

shell
cd /app/lambdas/order_api && zip -q /app/build/order_api.zip handler.py
cd /app/lambdas/outbox_relay && zip -q /app/build/outbox_relay.zip handler.py
ls -la /app/build/*.zip
output
-rw-r--r-- 1 root root  993 Apr 28 15:23 /app/build/order_api.zip
-rw-r--r-- 1 root root 1093 Apr 28 15:23 /app/build/outbox_relay.zip

[stdout]
-rw-r--r-- 1 root root  993 Apr 28 15:23 /app/build/order_api.zip
-rw-r--r-- 1 root root 1093 Apr 28 15:23 /app/build/outbox_relay.zip

Deploy both lambdas

shell
ORDER_API_ROLE=$(cat /app/build/order_api_role_arn)
RELAY_ROLE=$(cat /app/build/outbox_relay_role_arn)

aws lambda create-function \
  --function-name order-api \
  --runtime python3.11 \
  --role "$ORDER_API_ROLE" \
  --handler handler.handler \
  --zip-file fileb:///app/build/order_api.zip \
  --timeout 15 \
  --environment "Variables={AWS_ENDPOINT_URL=http://localstack:4566,ORDERS_TABLE=orders,OUTBOX_TABLE=outbox}" \
  --query 'FunctionArn' --output text

aws lambda create-function \
  --function-name outbox-relay \
  --runtime python3.11 \
  --role "$RELAY_ROLE" \
  --handler handler.handler \
  --zip-file fileb:///app/build/outbox_relay.zip \
  --timeout 30 \
  --environment "Variables={AWS_ENDPOINT_URL=http://localstack:4566,DEDUP_TABLE=processed_events,EVENT_BUS=order-events,DEDUP_TTL_SECONDS=86400}" \
  --query 'FunctionArn' --output text
output
arn:aws:lambda:us-east-1:000000000000:function:order-api
arn:aws:lambda:us-east-1:000000000000:function:outbox-relay

[stdout]
arn:aws:lambda:us-east-1:000000000000:function:order-api
arn:aws:lambda:us-east-1:000000000000:function:outbox-relay

Wait for lambdas active

shell
aws lambda wait function-active --function-name order-api && aws lambda wait function-active --function-name outbox-relay && echo OK
output
OK

[stdout]
OK
  • Create KMS CMK + alias and key policy
  • Create DynamoDB tables (orders, outbox w/ stream, processed_events w/ TTL)
  • Create SQS queues + DLQs encrypted with CMK
  • Create EventBridge bus + rules + targets
  • Create scoped IAM roles + policies for both lambdas
  • Package and deploy both Python 3.11 lambdas
  • Wire DDB stream event source mapping with ReportBatchItemFailures
  • Run end-to-end smoke test (create + cancel)

Wire event source mapping

shell
STREAM_ARN=$(cat /app/build/outbox_stream_arn)
aws lambda create-event-source-mapping \
  --function-name outbox-relay \
  --event-source-arn "$STREAM_ARN" \
  --starting-position LATEST \
  --batch-size 10 \
  --maximum-batching-window-in-seconds 1 \
  --function-response-types ReportBatchItemFailures \
  --query '{UUID:UUID,State:State,FunctionResponseTypes:FunctionResponseTypes}'
output
{
    "UUID": "f15a615d-3375-4a10-8a0d-69b0a5029c46",
    "State": "Creating",
    "FunctionResponseTypes": [
        "ReportBatchItemFailures"
    ]
}

[stdout]
{
    "UUID": "f15a615d-3375-4a10-8a0d-69b0a5029c46",
    "State": "Creating",
    "FunctionResponseTypes": [
        "ReportBatchItemFailures"
    ]
}

Wait until ESM is Enabled

shell
UUID=f15a615d-3375-4a10-8a0d-69b0a5029c46
for i in 1 2 3 4 5 6 7 8 9 10; do
  STATE=$(aws lambda get-event-source-mapping --uuid "$UUID" --query State --output text)
  echo "state=$STATE"
  if [ "$STATE" = "Enabled" ]; then break; fi
  sleep 2
done
output
state=Enabled

[stdout]
state=Enabled
Time for the smoke test.
  • Create KMS CMK + alias and key policy
  • Create DynamoDB tables (orders, outbox w/ stream, processed_events w/ TTL)
  • Create SQS queues + DLQs encrypted with CMK
  • Create EventBridge bus + rules + targets
  • Create scoped IAM roles + policies for both lambdas
  • Package and deploy both Python 3.11 lambdas
  • Wire DDB stream event source mapping with ReportBatchItemFailures
  • Run end-to-end smoke test (create + cancel)

Invoke order-api with OrderCreated

shell
PAYLOAD1=$(printf '{"order_id":"o-1","kind":"OrderCreated","amount":42}' | base64 -w0)
aws lambda invoke --function-name order-api --payload "$PAYLOAD1" --cli-binary-format base64 /tmp/out1.json >/dev/null
cat /tmp/out1.json; echo
output
{"statusCode": 200, "body": "{\"order_id\": \"o-1\", \"kind\": \"OrderCreated\", \"event_id\": \"c46683da-311f-4523-b7ec-2aebe902443d\"}"}

[stdout]
{"statusCode": 200, "body": "{\"order_id\": \"o-1\", \"kind\": \"OrderCreated\", \"event_id\": \"c46683da-311f-4523-b7ec-2aebe902443d\"}"}

Poll queues for first event

shell
CREATED_URL=http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/orders-created
CANCELLED_URL=http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/orders-cancelled

for i in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15; do
  CC=$(aws sqs get-queue-attributes --queue-url "$CREATED_URL" --attribute-names ApproximateNumberOfMessages --query 'Attributes.ApproximateNumberOfMessages' --output text)
  CN=$(aws sqs get-queue-attributes --queue-url "$CANCELLED_URL" --attribute-names ApproximateNumberOfMessages --query 'Attributes.ApproximateNumberOfMessages' --output text)
  DD=$(aws dynamodb scan --table-name processed_events --select COUNT --query Count --output text)
  echo "tick=$i created=$CC cancelled=$CN dedup=$DD"
  if [ "$CC" = "1" ] && [ "$CN" = "0" ] && [ "$DD" = "1" ]; then break; fi
  sleep 2
done
output
tick=1 created=1 cancelled=0 dedup=1

[stdout]
tick=1 created=1 cancelled=0 dedup=1
Already through. Now invoke with OrderCancelled.

Verify OrderCancelled fans only to cancelled queue

shell
CREATED_URL=http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/orders-created
CANCELLED_URL=http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/orders-cancelled

# drain orders-created so we can verify it stays at 0 after cancel
RECV=$(aws sqs receive-message --queue-url "$CREATED_URL" --max-number-of-messages 10 --wait-time-seconds 1 --visibility-timeout 30)
echo "received pre-test:"; echo "$RECV" | jq '.Messages[].Body | fromjson | {source,"detail-type",detail: (.detail|fromjson)}'
RH=$(echo "$RECV" | jq -r '.Messages[0].ReceiptHandle')
[ -n "$RH" ] && [ "$RH" != "null" ] && aws sqs delete-message --queue-url "$CREATED_URL" --receipt-handle "$RH"

PAYLOAD2=$(printf '{"order_id":"o-2","kind":"OrderCancelled","reason":"customer"}' | base64 -w0)
aws lambda invoke --function-name order-api --payload "$PAYLOAD2" --cli-binary-format base64 /tmp/out2.json >/dev/null
cat /tmp/out2.json; echo

for i in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15; do
  CC=$(aws sqs get-queue-attributes --queue-url "$CREATED_URL" --attribute-names ApproximateNumberOfMessages --query 'Attributes.ApproximateNumberOfMessages' --output text)
  CN=$(aws sqs get-queue-attributes --queue-url "$CANCELLED_URL" --attribute-names ApproximateNumberOfMessages --query 'Attributes.ApproximateNumberOfMessages' --output text)
  DD=$(aws dynamodb scan --table-name processed_events --select COUNT --query Count --output text)
  echo "tick=$i created=$CC cancelled=$CN dedup=$DD"
  if [ "$CC" = "0" ] && [ "$CN" = "1" ] && [ "$DD" = "2" ]; then break; fi
  sleep 2
done
output
received pre-test:
jq: error (at <stdin>:10): object ({"order_id"...) only strings can be parsed
{"statusCode": 200, "body": "{\"order_id\": \"o-2\", \"kind\": \"OrderCancelled\", \"event_id\": \"6620de34-bc9a-429f-a430-310f8f9a0f54\"}"}
tick=1 created=0 cancelled=0 dedup=1
tick=2 created=0 cancelled=1 dedup=2

[stdout]
received pre-test:
jq: error (at <stdin>:10): object ({"order_id"...) only strings can be parsed
{"statusCode": 200, "body": "{\"order_id\": \"o-2\", \"kind\": \"OrderCancelled\", \"event_id\": \"6620de34-bc9a-429f-a430-310f8f9a0f54\"}"}
tick=1 created=0 cancelled=0 dedup=1
tick=2 created=0 cancelled=1 dedup=2
Both events fanned correctly. Let me sanity-check the actual SQS payload shape.

Inspect cancelled message body

shell
CANCELLED_URL=http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/orders-cancelled
aws sqs receive-message --queue-url "$CANCELLED_URL" --max-number-of-messages 1 --visibility-timeout 1 --wait-time-seconds 1 | jq '.Messages[0].Body | fromjson | {source, "detail-type", detail}'
output
{
  "source": "outbox.relay",
  "detail-type": "OrderCancelled",
  "detail": {
    "order_id": "o-2",
    "kind": "OrderCancelled",
    "reason": "customer"
  }
}

[stdout]
{
  "source": "outbox.relay",
  "detail-type": "OrderCancelled",
  "detail": {
    "order_id": "o-2",
    "kind": "OrderCancelled",
    "reason": "customer"
  }
}
EventBridge envelope is correct: `source=outbox.relay`, `detail-type=OrderCancelled`, and the original payload in `detail`.
  • Create KMS CMK + alias and key policy
  • Create DynamoDB tables (orders, outbox w/ stream, processed_events w/ TTL)
  • Create SQS queues + DLQs encrypted with CMK
  • Create EventBridge bus + rules + targets
  • Create scoped IAM roles + policies for both lambdas
  • Package and deploy both Python 3.11 lambdas
  • Wire DDB stream event source mapping with ReportBatchItemFailures
  • Run end-to-end smoke test (create + cancel)
Build is up and end-to-end works. **What's wired:** - `alias/outbox-cmk` → CMK protecting the three tables and all four SQS queues. KMS key policy lets `events.amazonaws.com`, `dynamodb.amazonaws.com`, `sqs.amazonaws.com` use the key (so EventBridge can encrypt to the queues, DDB can wrap items). - `orders` (pk `order_id`/S), `outbox` (pk `event_id`/S, stream NEW_AND_OLD_IMAGES), `processed_events` (pk `event_id`/S, TTL on `ttl` attr). - `order-api` lambda does a single `TransactWriteItems` of the order row + outbox row carrying a UUID `event_id`. No half-states. - Outbox stream → `outbox-relay` ESM with `FunctionResponseTypes=[ReportBatchItemFailures]`, so per-record failures fail just that sequence number (relay returns `{"batchItemFailures":[{"itemIdentifier":seq}]}`). - Relay claims `event_id` via conditional `PutItem` on `processed_events` (with `ttl`), then `events:PutEvents` to bus `order-events` with `source=outbox.relay`, `detail-type=kind`. A redelivered stream record finds the dedup row and skips. - Bus has `on-order-created` and `on-order-cancelled` rules patterning `source` + `detail-type`, each routed to its own queue. `orders-created`/`orders-cancelled` each carry a redrive policy to their own DLQ (`maxReceiveCount=5`). - IAM: - `order-api-role`: DDB write only on `orders` + `outbox`, KMS scoped to the CMK ARN with `kms:ViaService = dynamodb.us-east-1.amazonaws.com`. No SQS, no events, no stream perms. - `outbox-relay-role`: stream actions scoped to outbox stream ARN only (cannot touch the orders stream , orders has no stream anyway), `PutItem` only on `processed_events`, `events:PutEvents` only on the bus ARN, KMS scoped to the CMK ARN. No SQS perms. **Smoke test results:** - `o-1 OrderCreated` → `orders-created=1, orders-cancelled=0, processed_events=1` - `o-2 OrderCancelled` → `orders-created=0, orders-cancelled=1, processed_events=2` Source files: `/app/lambdas/order_api/handler.py`, `/app/lambdas/outbox_relay/handler.py`, policies under `/app/policies/`, materialized policy JSON in `/app/build/`.
Final diff , what the agent changed

No file changes, the agent left the workspace untouched.

Verifier output , the proof behind the reward
tests/test.sh
============================= test session starts ==============================
platform linux -- Python 3.12.3, pytest-8.4.1, pluggy-1.6.0 -- /root/.cache/uv/archive-v0/bpB8WaC46DETmDaaXXbZa/bin/python
cachedir: .pytest_cache
rootdir: /tests
plugins: json-ctrf-0.3.5
collecting ... collected 20 items

../tests/test_outputs.py::test_01_cmk_alias_exists_and_enabled PASSED    [  5%]
../tests/test_outputs.py::test_02_orders_table_exists PASSED             [ 10%]
../tests/test_outputs.py::test_03_outbox_table_exists PASSED             [ 15%]
../tests/test_outputs.py::test_04_processed_events_table_exists PASSED   [ 20%]
../tests/test_outputs.py::test_05_custom_event_bus_exists PASSED         [ 25%]
../tests/test_outputs.py::test_06_orders_table_encrypted_with_cmk PASSED [ 30%]
../tests/test_outputs.py::test_07_outbox_table_encrypted_with_cmk PASSED [ 35%]
../tests/test_outputs.py::test_08_outbox_stream_is_new_and_old_images PASSED [ 40%]
../tests/test_outputs.py::test_09_processed_events_ttl_enabled PASSED    [ 45%]
../tests/test_outputs.py::test_10_both_rule_patterns_use_array_wrap_and_disjoint_types PASSED [ 50%]
../tests/test_outputs.py::test_11_each_rule_targets_only_its_intended_queue PASSED [ 55%]
../tests/test_outputs.py::test_12_both_main_queues_encrypted_with_cmk PASSED [ 60%]
../tests/test_outputs.py::test_13_main_queues_have_redrive_to_distinct_dlqs PASSED [ 65%]
../tests/test_outputs.py::test_14_queue_policies_scope_events_with_source_arn FAILED [ 70%]
../tests/test_outputs.py::test_15_relay_esm_has_batch_item_failures_on_outbox_stream PASSED [ 75%]
../tests/test_outputs.py::test_16_relay_role_is_scoped_not_wildcard PASSED [ 80%]
../tests/test_outputs.py::test_17_order_api_role_scoped_to_orders_and_outbox_only PASSED [ 85%]
../tests/test_outputs.py::test_18_e2e_order_created_routes_to_created_queue_only PASSED [ 90%]
../tests/test_outputs.py::test_19_e2e_order_cancelled_routes_to_cancelled_queue_only PASSED [ 95%]
../tests/test_outputs.py::test_20_e2e_idempotent_duplicate_does_not_double_fanout PASSED [100%]

=================================== FAILURES ===================================
_____________ test_14_queue_policies_scope_events_with_source_arn ______________

    def test_14_queue_policies_scope_events_with_source_arn():
        """Each main queue's resource policy must allow events.amazonaws.com
        principal ONLY when aws:SourceArn matches the rule ARN for that queue.
        This is the classic 'confused-deputy' protection that LLMs typically
        either omit or wildcard."""
        sqs = _client("sqs")
        mapping = [
            (QUEUE_CREATED, RULE_CREATED),
            (QUEUE_CANCELLED, RULE_CANCELLED),
        ]
        for qname, rule_name in mapping:
            url = _queue_url(qname)
            attrs = sqs.get_queue_attributes(QueueUrl=url, AttributeNames=["Policy"])[
                "Attributes"
            ]
            policy_str = attrs.get("Policy")
            assert policy_str, f"{qname} missing resource policy"
            policy = json.loads(policy_str)
            stmts = policy.get("Statement", [])
            if isinstance(stmts, dict):
                stmts = [stmts]
    
            matched = False
            for s in stmts:
                if s.get("Effect") != "Allow":
                    continue
                principal = s.get("Principal", {})
                svc = principal.get("Service") if isinstance(principal, dict) else None
                svc_list = _as_list(svc)
                if "events.amazonaws.com" not in svc_list:
                    continue
                actions = _as_list(s.get("Action"))
                if not any("SendMessage" in a or a == "sqs:*" for a in actions):
                    continue
                cond = s.get("Condition", {})
                arn_like = cond.get("ArnEquals") or cond.get("ArnLike") or {}
                src_arn = arn_like.get("aws:SourceArn")
                src_list = _as_list(src_arn)
                if any(rule_name in v for v in src_list):
                    matched = True
                    break
>           assert matched, (
                f"{qname} resource policy must include an Allow for "
                f"events.amazonaws.com scoped by aws:SourceArn containing "
                f"rule '{rule_name}' - confused-deputy protection"
            )
E           AssertionError: orders-created resource policy must include an Allow for events.amazonaws.com scoped by aws:SourceArn containing rule 'on-order-created' - confused-deputy protection
E           assert False

/tests/test_outputs.py:395: AssertionError
=============================== warnings summary ===============================
test_outputs.py: 88 warnings
  /root/.cache/uv/archive-v0/bpB8WaC46DETmDaaXXbZa/lib/python3.12/site-packages/botocore/auth.py:424: DeprecationWarning: datetime.datetime.utcnow() is deprecated and scheduled for removal in a future version. Use timezone-aware objects to represent datetimes in UTC: datetime.datetime.now(datetime.UTC).
    datetime_now = datetime.datetime.utcnow()

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
==================================== PASSES ====================================
=========================== short test summary info ============================
PASSED ../tests/test_outputs.py::test_01_cmk_alias_exists_and_enabled
PASSED ../tests/test_outputs.py::test_02_orders_table_exists
PASSED ../tests/test_outputs.py::test_03_outbox_table_exists
PASSED ../tests/test_outputs.py::test_04_processed_events_table_exists
PASSED ../tests/test_outputs.py::test_05_custom_event_bus_exists
PASSED ../tests/test_outputs.py::test_06_orders_table_encrypted_with_cmk
PASSED ../tests/test_outputs.py::test_07_outbox_table_encrypted_with_cmk
PASSED ../tests/test_outputs.py::test_08_outbox_stream_is_new_and_old_images
PASSED ../tests/test_outputs.py::test_09_processed_events_ttl_enabled
PASSED ../tests/test_outputs.py::test_10_both_rule_patterns_use_array_wrap_and_disjoint_types
PASSED ../tests/test_outputs.py::test_11_each_rule_targets_only_its_intended_queue
PASSED ../tests/test_outputs.py::test_12_both_main_queues_encrypted_with_cmk
PASSED ../tests/test_outputs.py::test_13_main_queues_have_redrive_to_distinct_dlqs
PASSED ../tests/test_outputs.py::test_15_relay_esm_has_batch_item_failures_on_outbox_stream
PASSED ../tests/test_outputs.py::test_16_relay_role_is_scoped_not_wildcard
PASSED ../tests/test_outputs.py::test_17_order_api_role_scoped_to_orders_and_outbox_only
PASSED ../tests/test_outputs.py::test_18_e2e_order_created_routes_to_created_queue_only
PASSED ../tests/test_outputs.py::test_19_e2e_order_cancelled_routes_to_cancelled_queue_only
PASSED ../tests/test_outputs.py::test_20_e2e_idempotent_duplicate_does_not_double_fanout
FAILED ../tests/test_outputs.py::test_14_queue_policies_scope_events_with_source_arn
================== 1 failed, 19 passed, 88 warnings in 21.51s ==================

Reproduce this trial: git checkout 2f94510 && PYTHONPATH=src python3 scripts/build_site.py , then open trial/trial_f50e42f2e8904a1c. Re-running the agent live requires EVAL_PLATFORM_ENABLE_OAUTH_SMOKE=1 and is non-deterministic.

Trial trial_f50e42f2e8904a1c · verifier authoritative; classifier explanatory.