SyncValsverifier → artifact → classifier → verdict
SyncVals · Trajectory

s3-sqs-image-pipeline-kms

claude-code claude-opus-4-7 ✗ failed BAD_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
BAD_FAILUREThe task is at fault, underspecified/contradictory instruction, brittle/flaky tests, or tests demanding undiscoverable behavior.
SubtypeRigid/Brittle Tests
Evidencetest_source_and_dest_buckets_use_customer_cmks and test_main_queue_and_dlq_exist_and_are_encrypted both failed with: 'assert c96f6e96-f2c6-40f8-86ad-0cdc2c324495 in alias/source-bucket-cmk' and 'assert 8f1b8db7-bfcb-4ca9-bb3e-52682a70117e' in 'alias/sqs-queue-cmk'. The agent correctly configured buckets and queues with CMK-based SSE using the alias form (e.g., KMSMasterKeyID: alias/source-bucket-cmk), which is the standard AWS best practice, but tests expect the UUID form to be present and fail when encountering the alias.
Root causeThe tests use brittle UUID-based assertions that reject the standard AWS practice of referencing CMKs by alias. When buckets/queues are configured with SSE-KMS using an alias, AWS returns the alias form in the configuration, not the UUID. The tests check 'assert uuid in returned_value' which fails when the returned value is an alias instead of a UUID, even though both refer to the same key and are functionally equivalent.
RecommendationModify tests to resolve the CMK alias to its UUID before comparison, or modify tests to accept both alias and UUID forms in the KMSMasterKeyID fields. The test's _resolve_key_id() helper already has the ability to resolve aliases to UUIDs - it should be called on the returned KMSMasterKeyID value before the assertion, not just on the expected value. This way, both 'alias/source-bucket-cmk' and its UUID would normalize to the same value for comparison."
Trajectory
Tool-by-tool agent trajectory
34 tool calls · 4 tool types · 46 steps
ok, nothing's built yet and the box is empty. localstack is at `http://localstack:4566`, creds are exported (`AWS_ACCESS_KEY_ID=test`, same for secret, region `us-east-1`), you've got `aws`, `python3`, `boto3`, `jq`, `zip`, `curl`. stand the whole thing up from scratch. we're building an image-ingest pipeline. someone drops an object into a source bucket and on the other end we want a processed copy in a dest bucket plus a row in dynamodb describing it. everything has to be SSE-KMS with customer-managed keys , the bucket on the way in, the queue in the middle, and the bucket on the way out. three separate CMKs, one per boundary. least privilege throughout. the verifier reads policy docs directly, so don't wildcard your way through kms. shape of it: - PUT to the source bucket fires an s3 ObjectCreated notification - notification lands on an SQS standard queue (SSE-KMS) - a lambda consumes the queue and for each record: reads the source object, writes a processed copy to the dest bucket at `processed/<same-key>`, and writes a row to ddb with `{object_key, source_size, processed_at, status: "OK"}` - there's a DLQ behind the main queue with a redrive policy - the handler does per-record error handling , bad records get reported back individually, good records in the same batch don't get retried done looks like: one PUT to the source bucket, and within 60s, exactly one object at `processed/<key>` in the dest bucket, exactly one ddb row keyed by `object_key`, and nothing in the DLQ. keys with spaces in them have to work too (the s3 event url-encodes them , you know where this is going). also, when the handler is invoked with a batch that contains a broken record alongside a good one, only the broken record's id comes back in the response and the good one isn't retried. couple of things to be careful about: the SQS visibility timeout needs to actually cover the lambda timeout or messages get redriven into the DLQ mid-processing. and the partial-batch-failure contract has two sides , both the event source mapping and the handler response shape need to match, or the whole batch retries on any single failure. the aws docs on `ReportBatchItemFailures` are worth a glance. names the verifier grabs by hand, use them exactly: | thing | name | |-|-| | source bucket | `ingest-source-bucket` | | dest bucket | `ingest-dest-bucket` | | main queue | `ingest-events` | | dlq | `ingest-dlq` | | source bucket CMK alias | `alias/source-bucket-cmk` | | sqs CMK alias | `alias/sqs-queue-cmk` | | dest bucket CMK alias | `alias/dest-bucket-cmk` | | lambda | `image-ingest-consumer` | | lambda role | `image-ingest-lambda-role` | | ddb table | `image-ingest-records` | ddb partition key is `object_key` (string), no sort key. lambda is python3.11, handler entrypoint `handler.lambda_handler`. localstack community 4.13.1. you've got 60 minutes.

Check memory dir and working dir

shell
ls /logs/agent/sessions/projects/-app/memory/ 2>/dev/null && echo "---" && ls /app/
output
---

[stdout]
---

Verify AWS connectivity and versions

shell
aws --endpoint-url=http://localstack:4566 sts get-caller-identity && echo "---" && aws --version && python3 --version
output
{
    "UserId": "AKIAIOSFODNN7EXAMPLE",
    "Account": "000000000000",
    "Arn": "arn:aws:iam::000000000000:root"
}
---
aws-cli/2.34.33 Python/3.14.4 Linux/6.10.14-linuxkit exe/aarch64.ubuntu.24
Python 3.12.3

[stdout]
{
    "UserId": "AKIAIOSFODNN7EXAMPLE",
    "Account": "000000000000",
    "Arn": "arn:aws:iam::000000000000:root"
}
---
aws-cli/2.34.33 Python/3.14.4 Linux/6.10.14-linuxkit exe/aarch64.ubuntu.24
Python 3.12.3

Create working dirs

shell
mkdir -p /app/build /app/policies && ls /app
output
build
policies

[stdout]
build
policies

Create 3 CMKs with aliases

shell
export AWS_ENDPOINT_URL=http://localstack:4566 && \
# Create 3 KMS keys
SRC_KEY_ID=$(aws kms create-key --description "source bucket CMK" --query 'KeyMetadata.KeyId' --output text) && \
SQS_KEY_ID=$(aws kms create-key --description "sqs queue CMK" --query 'KeyMetadata.KeyId' --output text) && \
DST_KEY_ID=$(aws kms create-key --description "dest bucket CMK" --query 'KeyMetadata.KeyId' --output text) && \
aws kms create-alias --alias-name alias/source-bucket-cmk --target-key-id "$SRC_KEY_ID" && \
aws kms create-alias --alias-name alias/sqs-queue-cmk --target-key-id "$SQS_KEY_ID" && \
aws kms create-alias --alias-name alias/dest-bucket-cmk --target-key-id "$DST_KEY_ID" && \
echo "SRC_KEY_ID=$SRC_KEY_ID" > /app/build/ids.env && \
echo "SQS_KEY_ID=$SQS_KEY_ID" >> /app/build/ids.env && \
echo "DST_KEY_ID=$DST_KEY_ID" >> /app/build/ids.env && \
cat /app/build/ids.env
output
SRC_KEY_ID=c96f6e96-f2c6-40f8-86ad-0cdc2c324495
SQS_KEY_ID=8f1b8db7-bfcb-4ca9-bb3e-52682a70117e
DST_KEY_ID=cafd591d-6305-4eca-89c0-a6be11f6c633

[stdout]
SRC_KEY_ID=c96f6e96-f2c6-40f8-86ad-0cdc2c324495
SQS_KEY_ID=8f1b8db7-bfcb-4ca9-bb3e-52682a70117e
DST_KEY_ID=cafd591d-6305-4eca-89c0-a6be11f6c633

Create buckets with SSE-KMS

shell
export AWS_ENDPOINT_URL=http://localstack:4566 && \
source /app/build/ids.env && \
# Create buckets with SSE-KMS
aws s3api create-bucket --bucket ingest-source-bucket && \
aws s3api create-bucket --bucket ingest-dest-bucket && \
aws s3api put-bucket-encryption --bucket ingest-source-bucket --server-side-encryption-configuration "{\"Rules\":[{\"ApplyServerSideEncryptionByDefault\":{\"SSEAlgorithm\":\"aws:kms\",\"KMSMasterKeyID\":\"alias/source-bucket-cmk\"},\"BucketKeyEnabled\":true}]}" && \
aws s3api put-bucket-encryption --bucket ingest-dest-bucket --server-side-encryption-configuration "{\"Rules\":[{\"ApplyServerSideEncryptionByDefault\":{\"SSEAlgorithm\":\"aws:kms\",\"KMSMasterKeyID\":\"alias/dest-bucket-cmk\"},\"BucketKeyEnabled\":true}]}" && \
echo "buckets done" && \
aws s3api get-bucket-encryption --bucket ingest-source-bucket && \
aws s3api get-bucket-encryption --bucket ingest-dest-bucket
output
{
    "Location": "/ingest-source-bucket"
}
{
    "Location": "/ingest-dest-bucket"
}
buckets done
{
    "ServerSideEncryptionConfiguration": {
        "Rules": [
            {
                "ApplyServerSideEncryptionByDefault": {
                    "SSEAlgorithm": "aws:kms",
                    "KMSMasterKeyID": "alias/source-bucket-cmk"
                },
                "BucketKeyEnabled": true
            }
        ]
    }
}
{
    "ServerSideEncryptionConfiguration": {
        "Rules": [
            {
                "ApplyServerSideEncryptionByDefault": {
                    "SSEAlgorithm": "aws:kms",
                    "KMSMasterKeyID": "alias/dest-bucket-cmk"
                },
                "BucketKeyEnabled": true
            }
        ]
    }
}

[stdout]
{
    "Location": "/ingest-source-bucket"
}
{
    "Location": "/ingest-dest-bucket"
}
buckets done
{
    "ServerSideEncryptionConfiguration": {
        "Rules": [
            {
                "ApplyServerSideEncryptionByDefault": {
                    "SSEAlgorithm": "aws:kms",
                    "KMSMasterKeyID": "alias/source-bucket-cmk"
                },
                "BucketKeyEnabled": true
            }
        ]
    }
}
{
    "ServerSideEncryptionConfiguration": {
        "Rules": [
            {
                "ApplyServerSideEncryptionByDefault": {
                    "SSEAlgorithm": "aws:kms",
                    "KMSMasterKeyID": "alias/dest-bucket-cmk"
                },
                "BucketKeyEnabled": true
            }
        ]
    }
}

Create DynamoDB table

shell
export AWS_ENDPOINT_URL=http://localstack:4566 && \
aws dynamodb create-table \
  --table-name image-ingest-records \
  --attribute-definitions AttributeName=object_key,AttributeType=S \
  --key-schema AttributeName=object_key,KeyType=HASH \
  --billing-mode PAY_PER_REQUEST \
  --query 'TableDescription.TableStatus' --output text
output
ACTIVE

[stdout]
ACTIVE

Create SQS DLQ and main queue

shell
export AWS_ENDPOINT_URL=http://localstack:4566 && \
source /app/build/ids.env && \
# Create DLQ first
DLQ_URL=$(aws sqs create-queue --queue-name ingest-dlq --attributes "{\"KmsMasterKeyId\":\"alias/sqs-queue-cmk\"}" --query 'QueueUrl' --output text) && \
DLQ_ARN=$(aws sqs get-queue-attributes --queue-url "$DLQ_URL" --attribute-names QueueArn --query 'Attributes.QueueArn' --output text) && \
echo "DLQ_URL=$DLQ_URL" >> /app/build/ids.env && \
echo "DLQ_ARN=$DLQ_ARN" >> /app/build/ids.env && \
# Main queue with redrive + visibility timeout covering lambda timeout
REDRIVE=$(printf '{"deadLetterTargetArn":"%s","maxReceiveCount":"3"}' "$DLQ_ARN") && \
Q_URL=$(aws sqs create-queue --queue-name ingest-events --attributes "{\"KmsMasterKeyId\":\"alias/sqs-queue-cmk\",\"VisibilityTimeout\":\"120\",\"RedrivePolicy\":$(printf '%s' "$REDRIVE" | python3 -c 'import sys,json; print(json.dumps(sys.stdin.read()))')}" --query 'QueueUrl' --output text) && \
Q_ARN=$(aws sqs get-queue-attributes --queue-url "$Q_URL" --attribute-names QueueArn --query 'Attributes.QueueArn' --output text) && \
echo "Q_URL=$Q_URL" >> /app/build/ids.env && \
echo "Q_ARN=$Q_ARN" >> /app/build/ids.env && \
cat /app/build/ids.env && \
echo "---" && \
aws sqs get-queue-attributes --queue-url "$Q_URL" --attribute-names All
output
SRC_KEY_ID=c96f6e96-f2c6-40f8-86ad-0cdc2c324495
SQS_KEY_ID=8f1b8db7-bfcb-4ca9-bb3e-52682a70117e
DST_KEY_ID=cafd591d-6305-4eca-89c0-a6be11f6c633
DLQ_URL=http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/ingest-dlq
DLQ_ARN=arn:aws:sqs:us-east-1:000000000000:ingest-dlq
Q_URL=http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/ingest-events
Q_ARN=arn:aws:sqs:us-east-1:000000000000:ingest-events
---
{
    "Attributes": {
        "CreatedTimestamp": "1776846736",
        "DelaySeconds": "0",
        "LastModifiedTimestamp": "1776846736",
        "MaximumMessageSize": "1048576",
        "MessageRetentionPeriod": "345600",
        "QueueArn": "arn:aws:sqs:us-east-1:000000000000:ingest-events",
        "ReceiveMessageWaitTimeSeconds": "0",
        "VisibilityTimeout": "120",
        "SqsManagedSseEnabled": "true",
        "KmsMasterKeyId": "alias/sqs-queue-cmk",
        "RedrivePolicy": "{\"deadLetterTargetArn\":\"arn:aws:sqs:us-east-1:000000000000:ingest-dlq\",\"maxReceiveCount\":\"3\"}",
        "ApproximateNumberOfMessages": "0",
        "ApproximateNumberOfMessagesDelayed": "0",
        "ApproximateNumberOfMessagesNotVisible": "0"
    }
}

[stdout]
SRC_KEY_ID=c96f6e96-f2c6-40f8-86ad-0cdc2c324495
SQS_KEY_ID=8f1b8db7-bfcb-4ca9-bb3e-52682a70117e
DST_KEY_ID=cafd591d-6305-4eca-89c0-a6be11f6c633
DLQ_URL=http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/ingest-dlq
DLQ_ARN=arn:aws:sqs:us-east-1:000000000000:ingest-dlq
Q_URL=http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/ingest-events
Q_ARN=arn:aws:sqs:us-east-1:000000000000:ingest-events
---
{
    "Attributes": {
        "CreatedTimestamp": "1776846736",
        "DelaySeconds": "0",
        "LastModifiedTimestamp": "1776846736",
        "MaximumMessageSize": "1048576",
        "MessageRetentionPeriod": "345600",
        "QueueArn": "arn:aws:sqs:us-east-1:000000000000:ingest-events",
        "ReceiveMessageWaitTimeSeconds": "0",
        "VisibilityTimeout": "120",
        "SqsManagedSseEnabled": "true",
        "KmsMasterKeyId": "alias/sqs-queue-cmk",
        "RedrivePolicy": "{\"deadLetterTargetArn\":\"arn:aws:sqs:us-east-1:000000000000:ingest-dlq\",\"maxReceiveCount\":\"3\"}",
        "ApproximateNumberOfMessages": "0",
        "ApproximateNumberOfMessagesDelayed": "0",
        "ApproximateNumberOfMessagesNotVisible": "0"
    }
}

Ensure CMK-only SSE on queues

shell
export AWS_ENDPOINT_URL=http://localstack:4566 && \
source /app/build/ids.env && \
aws sqs set-queue-attributes --queue-url "$Q_URL" --attributes '{"SqsManagedSseEnabled":"false","KmsMasterKeyId":"alias/sqs-queue-cmk"}' && \
aws sqs set-queue-attributes --queue-url "$DLQ_URL" --attributes '{"SqsManagedSseEnabled":"false","KmsMasterKeyId":"alias/sqs-queue-cmk"}' && \
aws sqs get-queue-attributes --queue-url "$Q_URL" --attribute-names KmsMasterKeyId SqsManagedSseEnabled && \
aws sqs get-queue-attributes --queue-url "$DLQ_URL" --attribute-names KmsMasterKeyId SqsManagedSseEnabled
output
{
    "Attributes": {
        "KmsMasterKeyId": "alias/sqs-queue-cmk",
        "SqsManagedSseEnabled": "false"
    }
}
{
    "Attributes": {
        "KmsMasterKeyId": "alias/sqs-queue-cmk",
        "SqsManagedSseEnabled": "false"
    }
}

[stdout]
{
    "Attributes": {
        "KmsMasterKeyId": "alias/sqs-queue-cmk",
        "SqsManagedSseEnabled": "false"
    }
}
{
    "Attributes": {
        "KmsMasterKeyId": "alias/sqs-queue-cmk",
        "SqsManagedSseEnabled": "false"
    }
}
Now the SQS queue policy so S3 can send events, and the IAM role for Lambda.

Set SQS resource policy for S3

shell
source /app/build/ids.env && \
cat > /app/policies/sqs-policy.json <<EOF
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "AllowS3SourceBucketToSend",
      "Effect": "Allow",
      "Principal": {"Service": "s3.amazonaws.com"},
      "Action": "sqs:SendMessage",
      "Resource": "$Q_ARN",
      "Condition": {
        "ArnEquals": {"aws:SourceArn": "arn:aws:s3:::ingest-source-bucket"}
      }
    }
  ]
}
EOF
export AWS_ENDPOINT_URL=http://localstack:4566 && \
aws sqs set-queue-attributes --queue-url "$Q_URL" --attributes "Policy=$(python3 -c 'import json; print(json.dumps(open("/app/policies/sqs-policy.json").read()))')" && \
aws sqs get-queue-attributes --queue-url "$Q_URL" --attribute-names Policy
output
{
    "Attributes": {
        "Policy": "{\\n  \"Version\": \"2012-10-17\",\\n  \"Statement\": [\\n    {\\n      \"Sid\": \"AllowS3SourceBucketToSend\",\\n      \"Effect\": \"Allow\",\\n      \"Principal\": {\"Service\": \"s3.amazonaws.com\"},\\n      \"Action\": \"sqs:SendMessage\",\\n      \"Resource\": \"arn:aws:sqs:us-east-1:000000000000:ingest-events\",\\n      \"Condition\": {\\n        \"ArnEquals\": {\"aws:SourceArn\": \"arn:aws:s3:::ingest-source-bucket\"}\\n      }\\n    }\\n  ]\\n}\\n"
    }
}

[stdout]
{
    "Attributes": {
        "Policy": "{\\n  \"Version\": \"2012-10-17\",\\n  \"Statement\": [\\n    {\\n      \"Sid\": \"AllowS3SourceBucketToSend\",\\n      \"Effect\": \"Allow\",\\n      \"Principal\": {\"Service\": \"s3.amazonaws.com\"},\\n      \"Action\": \"sqs:SendMessage\",\\n      \"Resource\": \"arn:aws:sqs:us-east-1:000000000000:ingest-events\",\\n      \"Condition\": {\\n        \"ArnEquals\": {\"aws:SourceArn\": \"arn:aws:s3:::ingest-source-bucket\"}\\n      }\\n    }\\n  ]\\n}\\n"
    }
}
ToolSearch
{
  "query": "select:TodoWrite",
  "max_results": 1
}

, output, 
{"type": "tool_reference", "tool_name": "TodoWrite"}
  • Create 3 CMKs + aliases
  • Create S3 source + dest buckets with SSE-KMS
  • Create DDB table
  • Create SQS DLQ + main queue with SSE-KMS + redrive
  • Attach SQS policy allowing S3 source bucket to send
  • Create IAM role with least-privilege policy + KMS grants
  • Write + package Lambda (partial-batch-failure, url-decode keys)
  • Deploy Lambda + ESM with ReportBatchItemFailures
  • Wire S3 ObjectCreated notification -> SQS
  • End-to-end test: happy path + key-with-spaces + partial-batch-failure
The SQS policy above got double-escaped. Let me fix by passing attributes as a file.

Re-set SQS policy via file

shell
source /app/build/ids.env && \
python3 -c "
import json
policy = {
  'Version': '2012-10-17',
  'Statement': [{
    'Sid': 'AllowS3SourceBucketToSend',
    'Effect': 'Allow',
    'Principal': {'Service': 's3.amazonaws.com'},
    'Action': 'sqs:SendMessage',
    'Resource': '$Q_ARN',
    'Condition': {'ArnEquals': {'aws:SourceArn': 'arn:aws:s3:::ingest-source-bucket'}}
  }]
}
attrs = {'Policy': json.dumps(policy)}
json.dump(attrs, open('/app/build/sqs-attrs.json', 'w'))
" && \
export AWS_ENDPOINT_URL=http://localstack:4566 && \
aws sqs set-queue-attributes --queue-url "$Q_URL" --attributes file:///app/build/sqs-attrs.json && \
aws sqs get-queue-attributes --queue-url "$Q_URL" --attribute-names Policy | python3 -c 'import json,sys; d=json.load(sys.stdin); print(json.dumps(json.loads(d["Attributes"]["Policy"]), indent=2))'
output
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "AllowS3SourceBucketToSend",
      "Effect": "Allow",
      "Principal": {
        "Service": "s3.amazonaws.com"
      },
      "Action": "sqs:SendMessage",
      "Resource": "arn:aws:sqs:us-east-1:000000000000:ingest-events",
      "Condition": {
        "ArnEquals": {
          "aws:SourceArn": "arn:aws:s3:::ingest-source-bucket"
        }
      }
    }
  ]
}

[stdout]
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "AllowS3SourceBucketToSend",
      "Effect": "Allow",
      "Principal": {
        "Service": "s3.amazonaws.com"
      },
      "Action": "sqs:SendMessage",
      "Resource": "arn:aws:sqs:us-east-1:000000000000:ingest-events",
      "Condition": {
        "ArnEquals": {
          "aws:SourceArn": "arn:aws:s3:::ingest-source-bucket"
        }
      }
    }
  ]
}
Now KMS key policies. The SQS CMK needs to allow S3 service to generate data keys (for SendMessage with SSE-KMS), and the Lambda role needs access to decrypt on the SQS key + source key, encrypt on dest key.

Store lambda role arn

shell
source /app/build/ids.env && \
LAMBDA_ROLE_ARN="arn:aws:iam::000000000000:role/image-ingest-lambda-role" && \
echo "LAMBDA_ROLE_ARN=$LAMBDA_ROLE_ARN" >> /app/build/ids.env
cat /app/build/ids.env
output
SRC_KEY_ID=c96f6e96-f2c6-40f8-86ad-0cdc2c324495
SQS_KEY_ID=8f1b8db7-bfcb-4ca9-bb3e-52682a70117e
DST_KEY_ID=cafd591d-6305-4eca-89c0-a6be11f6c633
DLQ_URL=http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/ingest-dlq
DLQ_ARN=arn:aws:sqs:us-east-1:000000000000:ingest-dlq
Q_URL=http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/ingest-events
Q_ARN=arn:aws:sqs:us-east-1:000000000000:ingest-events
LAMBDA_ROLE_ARN=arn:aws:iam::000000000000:role/image-ingest-lambda-role

[stdout]
SRC_KEY_ID=c96f6e96-f2c6-40f8-86ad-0cdc2c324495
SQS_KEY_ID=8f1b8db7-bfcb-4ca9-bb3e-52682a70117e
DST_KEY_ID=cafd591d-6305-4eca-89c0-a6be11f6c633
DLQ_URL=http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/ingest-dlq
DLQ_ARN=arn:aws:sqs:us-east-1:000000000000:ingest-dlq
Q_URL=http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/ingest-events
Q_ARN=arn:aws:sqs:us-east-1:000000000000:ingest-events
LAMBDA_ROLE_ARN=arn:aws:iam::000000000000:role/image-ingest-lambda-role
write · /app/build/make_kms_policies.py
#!/usr/bin/env python3
import json, os, subprocess

LAMBDA_ROLE_ARN = "arn:aws:iam::000000000000:role/image-ingest-lambda-role"
ACCOUNT = "000000000000"
ROOT = f"arn:aws:iam::{ACCOUNT}:root"
S3_SVC = "s3.amazonaws.com"
SQS_SVC = "sqs.amazonaws.com"

def base_root():
    return {
        "Sid": "EnableRootAdmin",
        "Effect": "Allow",
        "Principal": {"AWS": ROOT},
        "Action": "kms:*",
        "Resource": "*",
    }

# SOURCE bucket CMK: S3 uses it (bucket default encryption); Lambda decrypts objects.
source_key_policy = {
    "Version": "2012-10-17",
    "Statement": [
        base_root(),
        {
            "Sid": "AllowS3ServiceUse",
            "Effect": "Allow",
            "Principal": {"Service": S3_SVC},
            "Action": [
                "kms:Decrypt",
                "kms:GenerateDataKey",
                "kms:DescribeKey",
            ],
            "Resource": "*",
        },
        {
            "Sid": "AllowLambdaDecrypt",
            "Effect": "Allow",
            "Principal": {"AWS": LAMBDA_ROLE_ARN},
            "Action": [
                "kms:Decrypt",
                "kms:DescribeKey",
            ],
            "Resource": "*",
        },
    ],
}

# SQS CMK: S3 publishes events to SQS -> needs GenerateDataKey + Decrypt for encryption at rest.
# Lambda receives from SQS -> needs Decrypt.
sqs_key_policy = {
    "Version": "2012-10-17",
    "Statement": [
        base_root(),
        {
            "Sid": "AllowS3EventsEncrypt",
            "Effect": "Allow",
            "Principal": {"Service": S3_SVC},
            "Action": [
                "kms:GenerateDataKey",
                "kms:Decrypt",
            ],
            "Resource": "*",
        },
        {
            "Sid": "AllowLambdaDecrypt",
            "Effect": "Allow",
            "Principal": {"AWS": LAMBDA_ROLE_ARN},
            "Action": [
                "kms:Decrypt",
                "kms:DescribeKey",
            ],
            "Resource": "*",
        },
    ],
}

# DEST bucket CMK: Lambda encrypts objects on PutObject. S3 may need decrypt to serve reads later (not needed for pipeline).
dest_key_policy = {
    "Version": "2012-10-17",
    "Statement": [
        base_root(),
        {
            "Sid": "AllowLambdaEncrypt",
            "Effect": "Allow",
            "Principal": {"AWS": LAMBDA_ROLE_ARN},
            "Action": [
                "kms:Encrypt",
                "kms:GenerateDataKey",
                "kms:DescribeKey",
            ],
            "Resource": "*",
        },
    ],
}

with open("/app/policies/source-key-policy.json", "w") as f:
    json.dump(source_key_policy, f, indent=2)
with open("/app/policies/sqs-key-policy.json", "w") as f:
    json.dump(sqs_key_policy, f, indent=2)
with open("/app/policies/dest-key-policy.json", "w") as f:
    json.dump(dest_key_policy, f, indent=2)

print("policies written")

Apply KMS key policies

shell
python3 /app/build/make_kms_policies.py && \
export AWS_ENDPOINT_URL=http://localstack:4566 && \
source /app/build/ids.env && \
aws kms put-key-policy --key-id "$SRC_KEY_ID" --policy-name default --policy file:///app/policies/source-key-policy.json && \
aws kms put-key-policy --key-id "$SQS_KEY_ID" --policy-name default --policy file:///app/policies/sqs-key-policy.json && \
aws kms put-key-policy --key-id "$DST_KEY_ID" --policy-name default --policy file:///app/policies/dest-key-policy.json && \
echo "kms policies applied"
output
policies written
kms policies applied

[stdout]
policies written
kms policies applied
Now the IAM role + least-privilege policy.
write · /app/policies/lambda-trust.json
{
  "Version": "2012-10-17",
  "Statement": [{
    "Effect": "Allow",
    "Principal": {"Service": "lambda.amazonaws.com"},
    "Action": "sts:AssumeRole"
  }]
}
write · /app/build/make_lambda_policy.py
#!/usr/bin/env python3
import json, os

# Load dynamic ids from ids.env
ids = {}
for line in open("/app/build/ids.env"):
    line = line.strip()
    if not line: continue
    k, v = line.split("=", 1)
    ids[k] = v

region = "us-east-1"
account = "000000000000"

src_key_arn = f"arn:aws:kms:{region}:{account}:key/{ids['SRC_KEY_ID']}"
sqs_key_arn = f"arn:aws:kms:{region}:{account}:key/{ids['SQS_KEY_ID']}"
dst_key_arn = f"arn:aws:kms:{region}:{account}:key/{ids['DST_KEY_ID']}"

policy = {
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "Logs",
            "Effect": "Allow",
            "Action": [
                "logs:CreateLogGroup",
                "logs:CreateLogStream",
                "logs:PutLogEvents",
            ],
            "Resource": f"arn:aws:logs:{region}:{account}:log-group:/aws/lambda/image-ingest-consumer:*",
        },
        {
            "Sid": "SQSConsume",
            "Effect": "Allow",
            "Action": [
                "sqs:ReceiveMessage",
                "sqs:DeleteMessage",
                "sqs:GetQueueAttributes",
                "sqs:ChangeMessageVisibility",
            ],
            "Resource": ids["Q_ARN"],
        },
        {
            "Sid": "ReadSource",
            "Effect": "Allow",
            "Action": ["s3:GetObject"],
            "Resource": "arn:aws:s3:::ingest-source-bucket/*",
        },
        {
            "Sid": "WriteDest",
            "Effect": "Allow",
            "Action": ["s3:PutObject"],
            "Resource": "arn:aws:s3:::ingest-dest-bucket/processed/*",
        },
        {
            "Sid": "DDBWrite",
            "Effect": "Allow",
            "Action": ["dynamodb:PutItem"],
            "Resource": f"arn:aws:dynamodb:{region}:{account}:table/image-ingest-records",
        },
        {
            "Sid": "DecryptSourceObjects",
            "Effect": "Allow",
            "Action": ["kms:Decrypt", "kms:DescribeKey"],
            "Resource": src_key_arn,
        },
        {
            "Sid": "DecryptSQSMessages",
            "Effect": "Allow",
            "Action": ["kms:Decrypt", "kms:DescribeKey"],
            "Resource": sqs_key_arn,
        },
        {
            "Sid": "EncryptDestObjects",
            "Effect": "Allow",
            "Action": ["kms:Encrypt", "kms:GenerateDataKey", "kms:DescribeKey"],
            "Resource": dst_key_arn,
        },
    ],
}

with open("/app/policies/lambda-policy.json", "w") as f:
    json.dump(policy, f, indent=2)
print("wrote /app/policies/lambda-policy.json")

Create IAM role and attach policy

shell
python3 /app/build/make_lambda_policy.py && \
export AWS_ENDPOINT_URL=http://localstack:4566 && \
aws iam create-role --role-name image-ingest-lambda-role --assume-role-policy-document file:///app/policies/lambda-trust.json --query 'Role.Arn' --output text && \
aws iam put-role-policy --role-name image-ingest-lambda-role --policy-name image-ingest-lambda-inline --policy-document file:///app/policies/lambda-policy.json && \
aws iam get-role-policy --role-name image-ingest-lambda-role --policy-name image-ingest-lambda-inline --query 'PolicyDocument' | head -40
output
wrote /app/policies/lambda-policy.json
arn:aws:iam::000000000000:role/image-ingest-lambda-role
{
    "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/image-ingest-consumer:*"
        },
        {
            "Sid": "SQSConsume",
            "Effect": "Allow",
            "Action": [
                "sqs:ReceiveMessage",
                "sqs:DeleteMessage",
                "sqs:GetQueueAttributes",
                "sqs:ChangeMessageVisibility"
            ],
            "Resource": "arn:aws:sqs:us-east-1:000000000000:ingest-events"
        },
        {
            "Sid": "ReadSource",
            "Effect": "Allow",
            "Action": [
                "s3:GetObject"
            ],
            "Resource": "arn:aws:s3:::ingest-source-bucket/*"
        },
        {
            "Sid": "WriteDest",
            "Effect": "Allow",
            "Action": [
                "s3:PutObject"
            ],
            "Resource": "arn:aws:s3:::ingest-dest-bucket/processed/*"
        },

[stdout]
wrote /app/policies/lambda-policy.json
arn:aws:iam::000000000000:role/image-ingest-lambda-role
{
    "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/image-ingest-consumer:*"
        },
        {
            "Sid": "SQSConsume",
            "Effect": "Allow",
            "Action": [
                "sqs:ReceiveMessage",
                "sqs:DeleteMessage",
                "sqs:GetQueueAttributes",
                "sqs:ChangeMessageVisibility"
            ],
            "Resource": "arn:aws:sqs:us-east-1:000000000000:ingest-events"
        },
        {
            "Sid": "ReadSource",
            "Effect": "Allow",
            "Action": [
                "s3:GetObject"
            ],
            "Resource": "arn:aws:s3:::ingest-source-bucket/*"
        },
        {
            "Sid": "WriteDest",
            "Effect": "Allow",
            "Action": [
                "s3:PutObject"
            ],
            "Resource": "arn:aws:s3:::ingest-dest-bucket/processed/*"
        },
  • Create 3 CMKs + aliases
  • Create S3 source + dest buckets with SSE-KMS
  • Create DDB table
  • Create SQS DLQ + main queue with SSE-KMS + redrive
  • Attach SQS policy allowing S3 source bucket to send
  • Create IAM role with least-privilege policy + KMS grants
  • Write + package Lambda (partial-batch-failure, url-decode keys)
  • Deploy Lambda + ESM with ReportBatchItemFailures
  • Wire S3 ObjectCreated notification -> SQS
  • End-to-end test: happy path + key-with-spaces + partial-batch-failure
Now the Lambda handler. Key things: url-decode keys (S3 url-encodes spaces as `+` inside the key in event records , must use `unquote_plus`), per-record try/except, return `batchItemFailures` for the failed items only, explicit SSE-KMS on the PutObject.
write · /app/build/lambda/handler.py
import json
import logging
import os
import urllib.parse
from datetime import datetime, timezone

import boto3

log = logging.getLogger()
log.setLevel(logging.INFO)

DEST_BUCKET = os.environ["DEST_BUCKET"]
DDB_TABLE = os.environ["DDB_TABLE"]
DEST_KMS_KEY = os.environ["DEST_KMS_KEY_ALIAS"]

s3 = boto3.client("s3")
ddb = boto3.client("dynamodb")


def _process_record(record):
    body = json.loads(record["body"])
    s3_records = body.get("Records") or []
    if not s3_records:
        raise ValueError(f"no s3 Records in message body: {body!r}")

    for r in s3_records:
        bucket = r["s3"]["bucket"]["name"]
        encoded_key = r["s3"]["object"]["key"]
        key = urllib.parse.unquote_plus(encoded_key)

        obj = s3.get_object(Bucket=bucket, Key=key)
        data = obj["Body"].read()

        dest_key = f"processed/{key}"
        s3.put_object(
            Bucket=DEST_BUCKET,
            Key=dest_key,
            Body=data,
            ServerSideEncryption="aws:kms",
            SSEKMSKeyId=DEST_KMS_KEY,
        )

        ddb.put_item(
            TableName=DDB_TABLE,
            Item={
                "object_key": {"S": key},
                "source_size": {"N": str(len(data))},
                "processed_at": {"S": datetime.now(timezone.utc).isoformat()},
                "status": {"S": "OK"},
            },
        )


def lambda_handler(event, context):
    failures = []
    for record in event.get("Records", []):
        mid = record["messageId"]
        try:
            _process_record(record)
        except Exception as exc:
            log.exception("failed to process message %s: %s", mid, exc)
            failures.append({"itemIdentifier": mid})
    return {"batchItemFailures": failures}

Package Lambda zip

shell
cd /app/build/lambda && zip -q /app/build/lambda.zip handler.py && ls -la /app/build/lambda.zip
output
-rw-r--r-- 1 root root 946 Apr 22 08:34 /app/build/lambda.zip

[stdout]
-rw-r--r-- 1 root root 946 Apr 22 08:34 /app/build/lambda.zip

Create Lambda function

shell
export AWS_ENDPOINT_URL=http://localstack:4566 && \
source /app/build/ids.env && \
aws lambda create-function \
  --function-name image-ingest-consumer \
  --runtime python3.11 \
  --role "$LAMBDA_ROLE_ARN" \
  --handler handler.lambda_handler \
  --zip-file fileb:///app/build/lambda.zip \
  --timeout 60 \
  --environment "Variables={DEST_BUCKET=ingest-dest-bucket,DDB_TABLE=image-ingest-records,DEST_KMS_KEY_ALIAS=alias/dest-bucket-cmk}" \
  --query 'FunctionArn' --output text
output
arn:aws:lambda:us-east-1:000000000000:function:image-ingest-consumer

[stdout]
arn:aws:lambda:us-east-1:000000000000:function:image-ingest-consumer

Wait active, then create ESM with ReportBatchItemFailures

shell
export AWS_ENDPOINT_URL=http://localstack:4566 && \
source /app/build/ids.env && \
# wait until active
for i in 1 2 3 4 5 6 7 8 9 10; do
  s=$(aws lambda get-function-configuration --function-name image-ingest-consumer --query 'State' --output text 2>/dev/null)
  [ "$s" = "Active" ] && break
  sleep 1
done
echo "state=$s" && \
aws lambda create-event-source-mapping \
  --function-name image-ingest-consumer \
  --event-source-arn "$Q_ARN" \
  --batch-size 10 \
  --function-response-types ReportBatchItemFailures \
  --query 'UUID' --output text
output
state=Active
b7e23c30-a818-4168-b9d1-19a5b322e719

[stdout]
state=Active
b7e23c30-a818-4168-b9d1-19a5b322e719

Confirm ESM state

shell
export AWS_ENDPOINT_URL=http://localstack:4566 && \
aws lambda list-event-source-mappings --function-name image-ingest-consumer --query 'EventSourceMappings[0].{State:State,ResponseTypes:FunctionResponseTypes,EventSourceArn:EventSourceArn}'
output
{
    "State": "Enabled",
    "ResponseTypes": [
        "ReportBatchItemFailures"
    ],
    "EventSourceArn": "arn:aws:sqs:us-east-1:000000000000:ingest-events"
}

[stdout]
{
    "State": "Enabled",
    "ResponseTypes": [
        "ReportBatchItemFailures"
    ],
    "EventSourceArn": "arn:aws:sqs:us-east-1:000000000000:ingest-events"
}
Now wire S3 notification → SQS.
write · /app/build/notif.json
{
  "QueueConfigurations": [
    {
      "Id": "ingest-all-objects",
      "QueueArn": "arn:aws:sqs:us-east-1:000000000000:ingest-events",
      "Events": ["s3:ObjectCreated:*"]
    }
  ]
}

Configure S3 notification to SQS

shell
export AWS_ENDPOINT_URL=http://localstack:4566 && \
aws s3api put-bucket-notification-configuration --bucket ingest-source-bucket --notification-configuration file:///app/build/notif.json && \
aws s3api get-bucket-notification-configuration --bucket ingest-source-bucket
output
{
    "QueueConfigurations": [
        {
            "Id": "ingest-all-objects",
            "QueueArn": "arn:aws:sqs:us-east-1:000000000000:ingest-events",
            "Events": [
                "s3:ObjectCreated:*"
            ]
        }
    ]
}

[stdout]
{
    "QueueConfigurations": [
        {
            "Id": "ingest-all-objects",
            "QueueArn": "arn:aws:sqs:us-east-1:000000000000:ingest-events",
            "Events": [
                "s3:ObjectCreated:*"
            ]
        }
    ]
}
  • Create 3 CMKs + aliases
  • Create S3 source + dest buckets with SSE-KMS
  • Create DDB table
  • Create SQS DLQ + main queue with SSE-KMS + redrive
  • Attach SQS policy allowing S3 source bucket to send
  • Create IAM role with least-privilege policy + KMS grants
  • Write + package Lambda (partial-batch-failure, url-decode keys)
  • Deploy Lambda + ESM with ReportBatchItemFailures
  • Wire S3 ObjectCreated notification -> SQS
  • End-to-end test: happy path + key-with-spaces + partial-batch-failure
Now let's test: upload a file with a plain key and one with spaces.

Upload test objects to source bucket

shell
export AWS_ENDPOINT_URL=http://localstack:4566 && \
echo "hello world payload 1" > /tmp/img1.bin && \
echo "hello with spaces payload" > "/tmp/img with spaces.bin" && \
aws s3api put-object --bucket ingest-source-bucket --key "img1.bin" --body /tmp/img1.bin >/dev/null && \
aws s3api put-object --bucket ingest-source-bucket --key "folder/img with spaces.bin" --body "/tmp/img with spaces.bin" >/dev/null && \
echo "uploaded"
output
uploaded

[stdout]
uploaded

Poll for processing, then dump results

shell
export AWS_ENDPOINT_URL=http://localstack:4566 && \
for i in 1 2 3 4 5 6 7 8 9 10 11 12; do
  sleep 5
  N=$(aws s3 ls s3://ingest-dest-bucket/processed/ --recursive 2>/dev/null | wc -l)
  echo "attempt $i dest_count=$N"
  [ "$N" -ge 2 ] && break
done
echo "--- dest bucket contents:" && \
aws s3 ls s3://ingest-dest-bucket/processed/ --recursive && \
echo "--- ddb items:" && \
aws dynamodb scan --table-name image-ingest-records --output json | python3 -c 'import json,sys; d=json.load(sys.stdin); print("Count:", d["Count"]); [print(i) for i in d["Items"]]'
output
attempt 1 dest_count=2
--- dest bucket contents:
2026-04-22 08:35:12         26 processed/folder/img with spaces.bin
2026-04-22 08:35:12         22 processed/img1.bin
--- ddb items:
Count: 2
{'source_size': {'N': '22'}, 'processed_at': {'S': '2026-04-22T08:35:12.768549+00:00'}, 'object_key': {'S': 'img1.bin'}, 'status': {'S': 'OK'}}
{'source_size': {'N': '26'}, 'processed_at': {'S': '2026-04-22T08:35:12.867301+00:00'}, 'object_key': {'S': 'folder/img with spaces.bin'}, 'status': {'S': 'OK'}}

[stdout]
attempt 1 dest_count=2
--- dest bucket contents:
2026-04-22 08:35:12         26 processed/folder/img with spaces.bin
2026-04-22 08:35:12         22 processed/img1.bin
--- ddb items:
Count: 2
{'source_size': {'N': '22'}, 'processed_at': {'S': '2026-04-22T08:35:12.768549+00:00'}, 'object_key': {'S': 'img1.bin'}, 'status': {'S': 'OK'}}
{'source_size': {'N': '26'}, 'processed_at': {'S': '2026-04-22T08:35:12.867301+00:00'}, 'object_key': {'S': 'folder/img with spaces.bin'}, 'status': {'S': 'OK'}}
Happy path works , both the plain key and the key with spaces flowed through. Let's verify the DLQ is empty and the SSE on dest objects is customer-managed KMS, then check the partial-batch-failure contract by direct invoke.

Verify DLQ empty and dest SSE-KMS

shell
export AWS_ENDPOINT_URL=http://localstack:4566 && \
source /app/build/ids.env && \
echo "--- DLQ depth:" && \
aws sqs get-queue-attributes --queue-url "$DLQ_URL" --attribute-names ApproximateNumberOfMessages ApproximateNumberOfMessagesNotVisible && \
echo "--- Main queue depth:" && \
aws sqs get-queue-attributes --queue-url "$Q_URL" --attribute-names ApproximateNumberOfMessages ApproximateNumberOfMessagesNotVisible && \
echo "--- Verify dest object SSE:" && \
aws s3api head-object --bucket ingest-dest-bucket --key "folder/img with spaces.bin" --query '{SSE:ServerSideEncryption,Key:SSEKMSKeyId}'
output
Exit code 254
--- DLQ depth:
{
    "Attributes": {
        "ApproximateNumberOfMessages": "0",
        "ApproximateNumberOfMessagesNotVisible": "0"
    }
}
--- Main queue depth:
{
    "Attributes": {
        "ApproximateNumberOfMessages": "0",
        "ApproximateNumberOfMessagesNotVisible": "1"
    }
}
--- Verify dest object SSE:

aws: [ERROR]: An error occurred (404) when calling the HeadObject operation: Not Found

[error] tool reported failure

Head the dest objects (full key w/ processed/ prefix)

shell
export AWS_ENDPOINT_URL=http://localstack:4566 && \
aws s3api head-object --bucket ingest-dest-bucket --key "processed/folder/img with spaces.bin" --query '{SSE:ServerSideEncryption,Key:SSEKMSKeyId}' && \
echo "---" && \
aws s3api head-object --bucket ingest-dest-bucket --key "processed/img1.bin" --query '{SSE:ServerSideEncryption,Key:SSEKMSKeyId}'
output
{
    "SSE": "aws:kms",
    "Key": "arn:aws:kms:us-east-1:000000000000:key/alias/dest-bucket-cmk"
}
---
{
    "SSE": "aws:kms",
    "Key": "arn:aws:kms:us-east-1:000000000000:key/alias/dest-bucket-cmk"
}

[stdout]
{
    "SSE": "aws:kms",
    "Key": "arn:aws:kms:us-east-1:000000000000:key/alias/dest-bucket-cmk"
}
---
{
    "SSE": "aws:kms",
    "Key": "arn:aws:kms:us-east-1:000000000000:key/alias/dest-bucket-cmk"
}
Dest objects are encrypted with the dest CMK. The main queue briefly shows 1 in-flight from the final ESM poll , it'll drain. Now let's prove the partial-batch-failure contract with a direct invoke of the Lambda using a crafted payload (one good record + one broken record where the S3 object doesn't exist).

Test partial-batch-failure contract

shell
export AWS_ENDPOINT_URL=http://localstack:4566 && \
cat > /tmp/batch_event.json <<'EOF'
{
  "Records": [
    {
      "messageId": "good-msg-1",
      "body": "{\"Records\":[{\"s3\":{\"bucket\":{\"name\":\"ingest-source-bucket\"},\"object\":{\"key\":\"img1.bin\"}}}]}"
    },
    {
      "messageId": "bad-msg-2",
      "body": "{\"Records\":[{\"s3\":{\"bucket\":{\"name\":\"ingest-source-bucket\"},\"object\":{\"key\":\"does-not-exist.bin\"}}}]}"
    }
  ]
}
EOF
aws lambda invoke --function-name image-ingest-consumer --payload fileb:///tmp/batch_event.json /tmp/out.json >/tmp/invoke.json && \
echo "--- invoke meta:" && cat /tmp/invoke.json && echo "" && \
echo "--- lambda response:" && cat /tmp/out.json
output
--- invoke meta:
{
    "StatusCode": 200,
    "ExecutedVersion": "$LATEST"
}

--- lambda response:
{"batchItemFailures": [{"itemIdentifier": "bad-msg-2"}]}

[stdout]
--- invoke meta:
{
    "StatusCode": 200,
    "ExecutedVersion": "$LATEST"
}

--- lambda response:
{"batchItemFailures": [{"itemIdentifier": "bad-msg-2"}]}
Exactly the contract , only `bad-msg-2` comes back; `good-msg-1` will not be retried. Final sanity pass.

Final state check

shell
export AWS_ENDPOINT_URL=http://localstack:4566 && \
source /app/build/ids.env && \
echo "=== final state ===" && \
echo "--- DLQ:" && aws sqs get-queue-attributes --queue-url "$DLQ_URL" --attribute-names ApproximateNumberOfMessages && \
echo "--- Main Q:" && aws sqs get-queue-attributes --queue-url "$Q_URL" --attribute-names ApproximateNumberOfMessages ApproximateNumberOfMessagesNotVisible && \
echo "--- Dest bucket:" && aws s3 ls s3://ingest-dest-bucket/processed/ --recursive && \
echo "--- DDB rows:" && aws dynamodb scan --table-name image-ingest-records --select COUNT
output
=== final state ===
--- DLQ:
{
    "Attributes": {
        "ApproximateNumberOfMessages": "0"
    }
}
--- Main Q:
{
    "Attributes": {
        "ApproximateNumberOfMessages": "0",
        "ApproximateNumberOfMessagesNotVisible": "1"
    }
}
--- Dest bucket:
2026-04-22 08:35:12         26 processed/folder/img with spaces.bin
2026-04-22 08:35:59         22 processed/img1.bin
--- DDB rows:
{
    "Count": 2,
    "ScannedCount": 2,
    "ConsumedCapacity": null
}

[stdout]
=== final state ===
--- DLQ:
{
    "Attributes": {
        "ApproximateNumberOfMessages": "0"
    }
}
--- Main Q:
{
    "Attributes": {
        "ApproximateNumberOfMessages": "0",
        "ApproximateNumberOfMessagesNotVisible": "1"
    }
}
--- Dest bucket:
2026-04-22 08:35:12         26 processed/folder/img with spaces.bin
2026-04-22 08:35:59         22 processed/img1.bin
--- DDB rows:
{
    "Count": 2,
    "ScannedCount": 2,
    "ConsumedCapacity": null
}
  • Create 3 CMKs + aliases
  • Create S3 source + dest buckets with SSE-KMS
  • Create DDB table
  • Create SQS DLQ + main queue with SSE-KMS + redrive
  • Attach SQS policy allowing S3 source bucket to send
  • Create IAM role with least-privilege policy + KMS grants
  • Write + package Lambda (partial-batch-failure, url-decode keys)
  • Deploy Lambda + ESM with ReportBatchItemFailures
  • Wire S3 ObjectCreated notification -> SQS
  • End-to-end test: happy path + key-with-spaces + partial-batch-failure
All stood up and verified end-to-end. **What was built** - **KMS (3 CMKs, scoped policies , no wildcards on principals)** - `alias/source-bucket-cmk` , `s3.amazonaws.com` gets `Decrypt/GenerateDataKey/DescribeKey`; lambda role gets `Decrypt/DescribeKey` - `alias/sqs-queue-cmk` , `s3.amazonaws.com` gets `GenerateDataKey/Decrypt` (for S3→SQS publish at rest); lambda role gets `Decrypt/DescribeKey` - `alias/dest-bucket-cmk` , lambda role gets `Encrypt/GenerateDataKey/DescribeKey` only - **S3** , `ingest-source-bucket` + `ingest-dest-bucket`, both with bucket-default SSE-KMS bound to their CMK aliases - **SQS** , `ingest-events` (VisibilityTimeout=120s, > lambda 60s timeout; KmsMasterKeyId=alias/sqs-queue-cmk; SqsManagedSse=false; RedrivePolicy → `ingest-dlq` @ maxReceiveCount=3) + `ingest-dlq` with the same CMK. Resource policy on the main queue only allows `sqs:SendMessage` from `s3.amazonaws.com` with `aws:SourceArn = arn:aws:s3:::ingest-source-bucket` - **DynamoDB** , `image-ingest-records`, PK `object_key` (S), PAY_PER_REQUEST - **IAM** , `image-ingest-lambda-role` inline policy scoped to: logs for its own log group, SQS actions on `ingest-events` only, `s3:GetObject` on `ingest-source-bucket/*`, `s3:PutObject` on `ingest-dest-bucket/processed/*`, `dynamodb:PutItem` on the table, and the three KMS actions each scoped to the single relevant key ARN - **Lambda** , `image-ingest-consumer` (python3.11, `handler.lambda_handler`, 60s). Uses `urllib.parse.unquote_plus` on `event.Records[].s3.object.key` (handles the `+` encoding S3 does for spaces), per-record try/except, returns `{"batchItemFailures":[{itemIdentifier:…}]}`. Writes the dest object with explicit `ServerSideEncryption=aws:kms` + `SSEKMSKeyId=alias/dest-bucket-cmk` - **ESM** , on `ingest-events`, `FunctionResponseTypes=[ReportBatchItemFailures]` - **S3 notification** , `s3:ObjectCreated:*` on source → `ingest-events` **Verified** - PUT `img1.bin` → `processed/img1.bin` in dest + 1 DDB row, within ~5s - PUT `folder/img with spaces.bin` → `processed/folder/img with spaces.bin` + DDB row (url-decoded correctly) - Dest objects `head-object` → `ServerSideEncryption=aws:kms`, key=`alias/dest-bucket-cmk` - DLQ depth = 0 - Direct Lambda invoke with a batch of `{good-msg-1, bad-msg-2}` returned `{"batchItemFailures":[{"itemIdentifier":"bad-msg-2"}]}` , good one not reported, so it won't be retried
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/DEh02OYcxzBUxe0IU_7r9/bin/python
cachedir: .pytest_cache
rootdir: /tests
plugins: json-ctrf-0.3.5
collecting ... collected 18 items

../tests/test_outputs.py::test_aws_cli_binary_is_real PASSED             [  5%]
../tests/test_outputs.py::test_localstack_reachable PASSED               [ 11%]
../tests/test_outputs.py::test_source_and_dest_buckets_use_customer_cmks FAILED [ 16%]
../tests/test_outputs.py::test_main_queue_and_dlq_exist_and_are_encrypted FAILED [ 22%]
../tests/test_outputs.py::test_lambda_exists_with_expected_handler PASSED [ 27%]
../tests/test_outputs.py::test_ddb_table_exists PASSED                   [ 33%]
../tests/test_outputs.py::test_source_bucket_notification_targets_main_queue PASSED [ 38%]
../tests/test_outputs.py::test_main_queue_policy_allows_s3_service PASSED [ 44%]
../tests/test_outputs.py::test_sqs_cmk_allows_s3_service PASSED          [ 50%]
../tests/test_outputs.py::test_source_cmk_allows_lambda_role_decrypt PASSED [ 55%]
../tests/test_outputs.py::test_dest_cmk_allows_lambda_role_encrypt PASSED [ 61%]
../tests/test_outputs.py::test_lambda_role_has_kms_decrypt_on_sqs_cmk PASSED [ 66%]
../tests/test_outputs.py::test_main_queue_visibility_timeout_covers_lambda_timeout PASSED [ 72%]
../tests/test_outputs.py::test_event_source_mapping_declares_report_batch_item_failures PASSED [ 77%]
../tests/test_outputs.py::test_lambda_handler_returns_correct_response_shape PASSED [ 83%]
../tests/test_outputs.py::test_end_to_end_preserves_object_size PASSED   [ 88%]
../tests/test_outputs.py::test_end_to_end_key_with_spaces_is_decoded PASSED [ 94%]
../tests/test_outputs.py::test_end_to_end_upload_propagates_to_dest_and_ddb PASSED [100%]

=================================== FAILURES ===================================
________________ test_source_and_dest_buckets_use_customer_cmks ________________

s3 = <botocore.client.S3 object at 0xffff8d22bce0>
kms = <botocore.client.KMS object at 0xffff8cf8d220>

    def test_source_and_dest_buckets_use_customer_cmks(s3, kms):
        """Buckets use CMKs."""
        src_cfg = s3.get_bucket_encryption(Bucket=SRC_BUCKET)
        src_rules = src_cfg["ServerSideEncryptionConfiguration"]["Rules"]
        assert src_rules, f"{SRC_BUCKET} has no SSE rules"
        src_sse = src_rules[0]["ApplyServerSideEncryptionByDefault"]
        assert src_sse["SSEAlgorithm"] == "aws:kms", (
            f"{SRC_BUCKET} not using aws:kms: {src_sse}"
        )
        src_cmk_id = _resolve_key_id(kms, SRC_CMK_ALIAS)
>       assert src_cmk_id in src_sse.get("KMSMasterKeyID", ""), (
            f"{SRC_BUCKET} not using {SRC_CMK_ALIAS} ({src_cmk_id}), got "
            f"{src_sse.get('KMSMasterKeyID')}"
        )
E       AssertionError: ingest-source-bucket not using alias/source-bucket-cmk (c96f6e96-f2c6-40f8-86ad-0cdc2c324495), got alias/source-bucket-cmk
E       assert 'c96f6e96-f2c6-40f8-86ad-0cdc2c324495' in 'alias/source-bucket-cmk'
E        +  where 'alias/source-bucket-cmk' = <built-in method get of dict object at 0xffff8ce82b80>('KMSMasterKeyID', '')
E        +    where <built-in method get of dict object at 0xffff8ce82b80> = {'KMSMasterKeyID': 'alias/source-bucket-cmk', 'SSEAlgorithm': 'aws:kms'}.get

/tests/test_outputs.py:175: AssertionError
_______________ test_main_queue_and_dlq_exist_and_are_encrypted ________________

sqs = <botocore.client.SQS object at 0xffff8ceec8f0>
kms = <botocore.client.KMS object at 0xffff8cf8d220>

    def test_main_queue_and_dlq_exist_and_are_encrypted(sqs, kms):
        """Queues encrypted."""
        main_url = _queue_url(sqs, MAIN_QUEUE)
        main_attrs = _queue_attrs(sqs, main_url)
        assert main_attrs.get("KmsMasterKeyId"), (
            f"{MAIN_QUEUE} missing KmsMasterKeyId (SSE-KMS)"
        )
        expected = _resolve_key_id(kms, SQS_CMK_ALIAS)
>       assert expected in main_attrs["KmsMasterKeyId"] or main_attrs[
            "KmsMasterKeyId"
        ].endswith(expected), (
            f"{MAIN_QUEUE} encrypted with {main_attrs['KmsMasterKeyId']}, "
            f"expected {SQS_CMK_ALIAS} ({expected})"
        )
E       AssertionError: ingest-events encrypted with alias/sqs-queue-cmk, expected alias/sqs-queue-cmk (8f1b8db7-bfcb-4ca9-bb3e-52682a70117e)
E       assert ('8f1b8db7-bfcb-4ca9-bb3e-52682a70117e' in 'alias/sqs-queue-cmk' or False)
E        +  where False = <built-in method endswith of str object at 0xffff8cd54b30>('8f1b8db7-bfcb-4ca9-bb3e-52682a70117e')
E        +    where <built-in method endswith of str object at 0xffff8cd54b30> = 'alias/sqs-queue-cmk'.endswith

/tests/test_outputs.py:199: AssertionError
=============================== warnings summary ===============================
test_outputs.py: 61 warnings
  /root/.cache/uv/archive-v0/DEh02OYcxzBUxe0IU_7r9/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_aws_cli_binary_is_real
PASSED ../tests/test_outputs.py::test_localstack_reachable
PASSED ../tests/test_outputs.py::test_lambda_exists_with_expected_handler
PASSED ../tests/test_outputs.py::test_ddb_table_exists
PASSED ../tests/test_outputs.py::test_source_bucket_notification_targets_main_queue
PASSED ../tests/test_outputs.py::test_main_queue_policy_allows_s3_service
PASSED ../tests/test_outputs.py::test_sqs_cmk_allows_s3_service
PASSED ../tests/test_outputs.py::test_source_cmk_allows_lambda_role_decrypt
PASSED ../tests/test_outputs.py::test_dest_cmk_allows_lambda_role_encrypt
PASSED ../tests/test_outputs.py::test_lambda_role_has_kms_decrypt_on_sqs_cmk
PASSED ../tests/test_outputs.py::test_main_queue_visibility_timeout_covers_lambda_timeout
PASSED ../tests/test_outputs.py::test_event_source_mapping_declares_report_batch_item_failures
PASSED ../tests/test_outputs.py::test_lambda_handler_returns_correct_response_shape
PASSED ../tests/test_outputs.py::test_end_to_end_preserves_object_size
PASSED ../tests/test_outputs.py::test_end_to_end_key_with_spaces_is_decoded
PASSED ../tests/test_outputs.py::test_end_to_end_upload_propagates_to_dest_and_ddb
FAILED ../tests/test_outputs.py::test_source_and_dest_buckets_use_customer_cmks
FAILED ../tests/test_outputs.py::test_main_queue_and_dlq_exist_and_are_encrypted
================== 2 failed, 16 passed, 61 warnings in 16.48s ==================

Reproduce this trial: git checkout 2f94510 && PYTHONPATH=src python3 scripts/build_site.py , then open trial/trial_7226011c62844638. Re-running the agent live requires EVAL_PLATFORM_ENABLE_OAUTH_SMOKE=1 and is non-deterministic.

Trial trial_7226011c62844638 · verifier authoritative; classifier explanatory.