SyncValsverifier → artifact → classifier → verdict
SyncVals · Trajectory

apigw-sqs-fifo-direct-integration

claude-code claude-opus-4-7 ✓ resolved GOOD_SUCCESS ↑ 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_SUCCESSLegitimate solve, implements the asked-for behavior; tests verify real functionality.
SubtypeLegitimate Solution
EvidenceAll 19 tests passed including: test_stage_deployment_id_was_refreshed (verifies critical deployment layer), test_lambda_handler_idempotency_and_response_shape (verifies handler fix), test_integration_template_identifiers_are_request_derived (verifies VTL template), test_end_to_end_duplicate_post_is_idempotent (verifies idempotency), test_end_to_end_post_reaches_ddb_no_dlq (verifies full pipeline). Agent's raw log shows systematic construction: created DDB, FIFO queues with redrive, fixed Lambda role permissions (added DynamoDB:PutItem, SQS permissions), replaced handler with idempotent version using ConditionExpression, and properly returned batchItemFailures structure instead of broken 'failed' field.
Root causeAgent correctly understood the complex task requirements including the pre-broken Lambda that needed fixing (idempotency + response shape), understood the AWS component relationships, implemented VTL request templates for FIFO message group/dedup IDs, created proper IAM policies, and correctly managed the API Gateway deployment cycle to ensure stage changes were visible to clients.
RecommendationN/A - task is fine
Trajectory
Tool-by-tool agent trajectory
36 tool calls · 4 tool types · 52 steps
ok so we need an order-ingest pipeline on localstack. localstack is at `http://localstack:4566`, creds are already exported (`AWS_ACCESS_KEY_ID=test`, same for secret, region `us-east-1`), you've got `aws`, `python3`, `boto3`, `jq`, `zip`, `curl`. build the whole thing. a seeder (`/app/setup.sh`, already ran) has pre-created the consumer Lambda (`orders-consumer`) and its role (`orders-consumer-role`) , **both broken by design**. the handler has the wrong batch-failure response shape and isn't idempotent, and the role is missing the AWS actions it actually needs to do its job. you fix those. everything else is up to you to build from scratch: - the rest api + stage + resource + method + integration + deployment - the apigw→sqs iam role - the two fifo queues (main + dlq) with redrive - the ddb table - the event source mapping from the main queue to the pre-seeded lambda IAM policies too , every role needs whatever actions its job requires. merchants POST orders to a rest api. the api drops the order onto a fifo queue, a consumer lambda drains the queue into dynamodb, and anything that keeps failing lands in a dlq. duplicate POSTs for the same order must be no-ops at the storage layer , second POST succeeds http-wise but the stored row doesn't change. done looks like this: one `POST /dev/orders` from inside the compose network with body `{"order_id":..., "merchant_id":..., "amount":...}` and within ~30s: - http 200 back - exactly one row in the `orders` table keyed by `order_id`, carrying merchant_id and amount - nothing in the dlq - re-POST the same body → still 200, still one row, unchanged - two different order_ids under the same merchant preserve posted order in the table timestamps shape of it: - rest api, stage `dev`, resource `/orders`, method `POST`. integration is a direct aws-service call to sqs , not AWS_PROXY, not a lambda proxy. api gateway assumes a role and hands the message straight to the queue. - the queue is fifo. content-based dedup off. a separate fifo dlq is wired via redrive. - a lambda consumes the queue via an event source mapping, writes to ddb, and reports per-record failures so a single bad record doesn't retry the whole batch. - ddb table `orders`, partition key `order_id` (String). also: api gateway is two-layer , there's the CONFIGURATION (resources, methods, integration, role, mapping templates) and there's the live STAGE that clients actually hit. editing configuration in place doesn't promote anything; clients keep seeing the old behavior until you create a NEW deployment for the stage. so after every wiring change, call `apigateway create-deployment` against this rest-api targeting stage `dev` , once at the very end, once after a fix, every time. forgetting this is the single most common reason an otherwise-correct setup still looks broken. names the verifier grabs by hand, use them exactly: | thing | name | |-|-| | rest api | `orders-api` | | stage | `dev` | | resource path | `/orders` | | method | `POST` | | main queue | `orders.fifo` | | dlq | `orders-dlq.fifo` | | apigw→sqs role | `apigw-to-sqs-role` | | consumer lambda | `orders-consumer` | | consumer lambda role | `orders-consumer-role` | | ddb table | `orders` (pk `order_id` String) | python3.11 for the lambda. the lambda runs on the shared compose network so `http://localstack:4566` is reachable from inside it. localstack community 4.13.1. you have up to 60 minutes.

List app directory and view setup script

shell
ls /app/ && cat /app/setup.sh 2>/dev/null | head -100
output
setup.sh
starter
#!/bin/bash
[redacted: decontamination sentinel]
[redacted: decontamination sentinel]
#
# Pre-seeds the consumer Lambda + its role with a broken-by-design
# handler and incomplete IAM. The agent has to build everything else
# (queues, DDB, apigw, integration, deployment, ESM) AND fix this
# Lambda's handler + role. Without the pre-seeded Lambda, Opus 4.7
# tends to read the prose and forget the consumer path entirely.

set -euo pipefail

REGION="${AWS_DEFAULT_REGION:-us-east-1}"
ACCOUNT_ID="000000000000"

LAMBDA_FUNC="orders-consumer"
LAMBDA_ROLE="orders-consumer-role"

log() { echo "[setup] $*" >&2; }

log "waiting for localstack"
for _ in $(seq 1 80); do
  HEALTH=$(curl -sf http://localstack:4566/_localstack/health || true)
  echo "$HEALTH" | grep -qE '"lambda": "(available|running)"' \
    && echo "$HEALTH" | grep -qE '"iam": "(available|running)"' \
    && break
  sleep 2
done

log "creating Lambda consumer role (deliberately incomplete)"
TRUST=$(cat <<'JSON'
{
  "Version": "2012-10-17",
  "Statement": [
    {"Effect": "Allow", "Principal": {"Service": "lambda.amazonaws.com"}, "Action": "sts:AssumeRole"}
  ]
}
JSON
)
aws iam create-role \
  --role-name "$LAMBDA_ROLE" \
  --assume-role-policy-document "$TRUST" >/dev/null
aws iam attach-role-policy \
  --role-name "$LAMBDA_ROLE" \
  --policy-arn arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole
# Note: no dynamodb:PutItem, no sqs perms. Agent fixes this.
ROLE_ARN=$(aws iam get-role --role-name "$LAMBDA_ROLE" --query 'Role.Arn' --output text)

log "packaging Lambda (broken-by-design inline handler)"
WORKDIR="$(mktemp -d)"
cat > "${WORKDIR}/handler.py" <<'PY'
"""Orders consumer - broken by design.

Known issues (agent must fix):
  - Not idempotent: a duplicate message will try to PutItem again,
    which will either overwrite (wrong) or fail (wrong shape).
  - Returns a per-record 'failed' list instead of the AWS-required
    batchItemFailures shape for partial-batch-failure reporting.
"""

import json
import os
import time
import boto3

_endpoint = os.environ.get("AWS_ENDPOINT_URL", "http://localstack:4566")
ddb = boto3.client("dynamodb", endpoint_url=_endpoint)

TABLE_NAME = os.environ.get("TABLE_NAME", "orders")


def _process_record(record):
    payload = json.loads(record["body"])
    order_id = payload["order_id"]
    merchant_id = payload["merchant_id"]
    amount = int(payload["amount"])

    ddb.put_item(
        TableName=TABLE_NAME,
        Item={
            "order_id": {"S": order_id},
            "merchant_id": {"S": merchant_id},
            "amount": {"N": str(amount)},
            "created_at": {"N": str(int(time.time()))},
        },
    )


def lambda_handler(event, context):
    failed = []
    for record in event.get("Records", []):
        try:
            _process_record(record)
        except Exception as e:
            print(f"[error] msgId={record.get('messageId')} {type(e).__name__}: {e}")
            failed.append({"itemIdentifier": record["messageId"]})

    return {"failed": failed}
PY
(cd "$WORKDIR" && zip -q handler.zip handler.py)

[stdout]
setup.sh
starter
#!/bin/bash
[redacted: decontamination sentinel]
[redacted: decontamination sentinel]
#
# Pre-seeds the consumer Lambda + its role with a broken-by-design
# handler and incomplete IAM. The agent has to build everything else
# (queues, DDB, apigw, integration, deployment, ESM) AND fix this
# Lambda's handler + role. Without the pre-seeded Lambda, Opus 4.7
# tends to read the prose and forget the consumer path entirely.

set -euo pipefail

REGION="${AWS_DEFAULT_REGION:-us-east-1}"
ACCOUNT_ID="000000000000"

LAMBDA_FUNC="orders-consumer"
LAMBDA_ROLE="orders-consumer-role"

log() { echo "[setup] $*" >&2; }

log "waiting for localstack"
for _ in $(seq 1 80); do
  HEALTH=$(curl -sf http://localstack:4566/_localstack/health || true)
  echo "$HEALTH" | grep -qE '"lambda": "(available|running)"' \
    && echo "$HEALTH" | grep -qE '"iam": "(available|running)"' \
    && break
  sleep 2
done

log "creating Lambda consumer role (deliberately incomplete)"
TRUST=$(cat <<'JSON'
{
  "Version": "2012-10-17",
  "Statement": [
    {"Effect": "Allow", "Principal": {"Service": "lambda.amazonaws.com"}, "Action": "sts:AssumeRole"}
  ]
}
JSON
)
aws iam create-role \
  --role-name "$LAMBDA_ROLE" \
  --assume-role-policy-document "$TRUST" >/dev/null
aws iam attach-role-policy \
  --role-name "$LAMBDA_ROLE" \
  --policy-arn arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole
# Note: no dynamodb:PutItem, no sqs perms. Agent fixes this.
ROLE_ARN=$(aws iam get-role --role-name "$LAMBDA_ROLE" --query 'Role.Arn' --output text)

log "packaging Lambda (broken-by-design inline handler)"
WORKDIR="$(mktemp -d)"
cat > "${WORKDIR}/handler.py" <<'PY'
"""Orders consumer - broken by design.

Known issues (agent must fix):
  - Not idempotent: a duplicate message will try to PutItem again,
    which will either overwrite (wrong) or fail (wrong shape).
  - Returns a per-record 'failed' list instead of the AWS-required
    batchItemFailures shape for partial-batch-failure reporting.
"""

import json
import os
import time
import boto3

_endpoint = os.environ.get("AWS_ENDPOINT_URL", "http://localstack:4566")
ddb = boto3.client("dynamodb", endpoint_url=_endpoint)

TABLE_NAME = os.environ.get("TABLE_NAME", "orders")


def _process_record(record):
    payload = json.loads(record["body"])
    order_id = payload["order_id"]
    merchant_id = payload["merchant_id"]
    amount = int(payload["amount"])

    ddb.put_item(
        TableName=TABLE_NAME,
        Item={
            "order_id": {"S": order_id},
            "merchant_id": {"S": merchant_id},
            "amount": {"N": str(amount)},
            "created_at": {"N": str(int(time.time()))},
        },
    )


def lambda_handler(event, context):
    failed = []
    for record in event.get("Records", []):
        try:
            _process_record(record)
        except Exception as e:
            print(f"[error] msgId={record.get('messageId')} {type(e).__name__}: {e}")
            failed.append({"itemIdentifier": record["messageId"]})

    return {"failed": failed}
PY
(cd "$WORKDIR" && zip -q handler.zip handler.py)

View rest of setup script

shell
cat /app/setup.sh | tail -100
output
for _ in $(seq 1 80); do
  HEALTH=$(curl -sf http://localstack:4566/_localstack/health || true)
  echo "$HEALTH" | grep -qE '"lambda": "(available|running)"' \
    && echo "$HEALTH" | grep -qE '"iam": "(available|running)"' \
    && break
  sleep 2
done

log "creating Lambda consumer role (deliberately incomplete)"
TRUST=$(cat <<'JSON'
{
  "Version": "2012-10-17",
  "Statement": [
    {"Effect": "Allow", "Principal": {"Service": "lambda.amazonaws.com"}, "Action": "sts:AssumeRole"}
  ]
}
JSON
)
aws iam create-role \
  --role-name "$LAMBDA_ROLE" \
  --assume-role-policy-document "$TRUST" >/dev/null
aws iam attach-role-policy \
  --role-name "$LAMBDA_ROLE" \
  --policy-arn arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole
# Note: no dynamodb:PutItem, no sqs perms. Agent fixes this.
ROLE_ARN=$(aws iam get-role --role-name "$LAMBDA_ROLE" --query 'Role.Arn' --output text)

log "packaging Lambda (broken-by-design inline handler)"
WORKDIR="$(mktemp -d)"
cat > "${WORKDIR}/handler.py" <<'PY'
"""Orders consumer - broken by design.

Known issues (agent must fix):
  - Not idempotent: a duplicate message will try to PutItem again,
    which will either overwrite (wrong) or fail (wrong shape).
  - Returns a per-record 'failed' list instead of the AWS-required
    batchItemFailures shape for partial-batch-failure reporting.
"""

import json
import os
import time
import boto3

_endpoint = os.environ.get("AWS_ENDPOINT_URL", "http://localstack:4566")
ddb = boto3.client("dynamodb", endpoint_url=_endpoint)

TABLE_NAME = os.environ.get("TABLE_NAME", "orders")


def _process_record(record):
    payload = json.loads(record["body"])
    order_id = payload["order_id"]
    merchant_id = payload["merchant_id"]
    amount = int(payload["amount"])

    ddb.put_item(
        TableName=TABLE_NAME,
        Item={
            "order_id": {"S": order_id},
            "merchant_id": {"S": merchant_id},
            "amount": {"N": str(amount)},
            "created_at": {"N": str(int(time.time()))},
        },
    )


def lambda_handler(event, context):
    failed = []
    for record in event.get("Records", []):
        try:
            _process_record(record)
        except Exception as e:
            print(f"[error] msgId={record.get('messageId')} {type(e).__name__}: {e}")
            failed.append({"itemIdentifier": record["messageId"]})

    return {"failed": failed}
PY
(cd "$WORKDIR" && zip -q handler.zip handler.py)

log "creating Lambda function"
aws lambda create-function \
  --function-name "$LAMBDA_FUNC" \
  --runtime python3.11 \
  --role "$ROLE_ARN" \
  --handler handler.lambda_handler \
  --timeout 30 \
  --memory-size 512 \
  --environment "Variables={AWS_ENDPOINT_URL=http://localstack:4566,TABLE_NAME=orders}" \
  --zip-file "fileb://${WORKDIR}/handler.zip" >/dev/null

for _ in $(seq 1 30); do
  STATE=$(aws lambda get-function --function-name "$LAMBDA_FUNC" \
    --query 'Configuration.State' --output text 2>/dev/null || echo "Pending")
  [ "$STATE" = "Active" ] && break
  sleep 1
done
log "Lambda $LAMBDA_FUNC ready"

log "done"

[stdout]
for _ in $(seq 1 80); do
  HEALTH=$(curl -sf http://localstack:4566/_localstack/health || true)
  echo "$HEALTH" | grep -qE '"lambda": "(available|running)"' \
    && echo "$HEALTH" | grep -qE '"iam": "(available|running)"' \
    && break
  sleep 2
done

log "creating Lambda consumer role (deliberately incomplete)"
TRUST=$(cat <<'JSON'
{
  "Version": "2012-10-17",
  "Statement": [
    {"Effect": "Allow", "Principal": {"Service": "lambda.amazonaws.com"}, "Action": "sts:AssumeRole"}
  ]
}
JSON
)
aws iam create-role \
  --role-name "$LAMBDA_ROLE" \
  --assume-role-policy-document "$TRUST" >/dev/null
aws iam attach-role-policy \
  --role-name "$LAMBDA_ROLE" \
  --policy-arn arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole
# Note: no dynamodb:PutItem, no sqs perms. Agent fixes this.
ROLE_ARN=$(aws iam get-role --role-name "$LAMBDA_ROLE" --query 'Role.Arn' --output text)

log "packaging Lambda (broken-by-design inline handler)"
WORKDIR="$(mktemp -d)"
cat > "${WORKDIR}/handler.py" <<'PY'
"""Orders consumer - broken by design.

Known issues (agent must fix):
  - Not idempotent: a duplicate message will try to PutItem again,
    which will either overwrite (wrong) or fail (wrong shape).
  - Returns a per-record 'failed' list instead of the AWS-required
    batchItemFailures shape for partial-batch-failure reporting.
"""

import json
import os
import time
import boto3

_endpoint = os.environ.get("AWS_ENDPOINT_URL", "http://localstack:4566")
ddb = boto3.client("dynamodb", endpoint_url=_endpoint)

TABLE_NAME = os.environ.get("TABLE_NAME", "orders")


def _process_record(record):
    payload = json.loads(record["body"])
    order_id = payload["order_id"]
    merchant_id = payload["merchant_id"]
    amount = int(payload["amount"])

    ddb.put_item(
        TableName=TABLE_NAME,
        Item={
            "order_id": {"S": order_id},
            "merchant_id": {"S": merchant_id},
            "amount": {"N": str(amount)},
            "created_at": {"N": str(int(time.time()))},
        },
    )


def lambda_handler(event, context):
    failed = []
    for record in event.get("Records", []):
        try:
            _process_record(record)
        except Exception as e:
            print(f"[error] msgId={record.get('messageId')} {type(e).__name__}: {e}")
            failed.append({"itemIdentifier": record["messageId"]})

    return {"failed": failed}
PY
(cd "$WORKDIR" && zip -q handler.zip handler.py)

log "creating Lambda function"
aws lambda create-function \
  --function-name "$LAMBDA_FUNC" \
  --runtime python3.11 \
  --role "$ROLE_ARN" \
  --handler handler.lambda_handler \
  --timeout 30 \
  --memory-size 512 \
  --environment "Variables={AWS_ENDPOINT_URL=http://localstack:4566,TABLE_NAME=orders}" \
  --zip-file "fileb://${WORKDIR}/handler.zip" >/dev/null

for _ in $(seq 1 30); do
  STATE=$(aws lambda get-function --function-name "$LAMBDA_FUNC" \
    --query 'Configuration.State' --output text 2>/dev/null || echo "Pending")
  [ "$STATE" = "Active" ] && break
  sleep 1
done
log "Lambda $LAMBDA_FUNC ready"

log "done"

Check starter directory

shell
ls /app/starter/ 2>/dev/null && echo "---" && cat /app/starter/* 2>/dev/null | head -200
output
setup.sh
---
#!/bin/bash
[redacted: decontamination sentinel]
[redacted: decontamination sentinel]
#
# Pre-seeds the consumer Lambda + its role with a broken-by-design
# handler and incomplete IAM. The agent has to build everything else
# (queues, DDB, apigw, integration, deployment, ESM) AND fix this
# Lambda's handler + role. Without the pre-seeded Lambda, Opus 4.7
# tends to read the prose and forget the consumer path entirely.

set -euo pipefail

REGION="${AWS_DEFAULT_REGION:-us-east-1}"
ACCOUNT_ID="000000000000"

LAMBDA_FUNC="orders-consumer"
LAMBDA_ROLE="orders-consumer-role"

log() { echo "[setup] $*" >&2; }

log "waiting for localstack"
for _ in $(seq 1 80); do
  HEALTH=$(curl -sf http://localstack:4566/_localstack/health || true)
  echo "$HEALTH" | grep -qE '"lambda": "(available|running)"' \
    && echo "$HEALTH" | grep -qE '"iam": "(available|running)"' \
    && break
  sleep 2
done

log "creating Lambda consumer role (deliberately incomplete)"
TRUST=$(cat <<'JSON'
{
  "Version": "2012-10-17",
  "Statement": [
    {"Effect": "Allow", "Principal": {"Service": "lambda.amazonaws.com"}, "Action": "sts:AssumeRole"}
  ]
}
JSON
)
aws iam create-role \
  --role-name "$LAMBDA_ROLE" \
  --assume-role-policy-document "$TRUST" >/dev/null
aws iam attach-role-policy \
  --role-name "$LAMBDA_ROLE" \
  --policy-arn arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole
# Note: no dynamodb:PutItem, no sqs perms. Agent fixes this.
ROLE_ARN=$(aws iam get-role --role-name "$LAMBDA_ROLE" --query 'Role.Arn' --output text)

log "packaging Lambda (broken-by-design inline handler)"
WORKDIR="$(mktemp -d)"
cat > "${WORKDIR}/handler.py" <<'PY'
"""Orders consumer - broken by design.

Known issues (agent must fix):
  - Not idempotent: a duplicate message will try to PutItem again,
    which will either overwrite (wrong) or fail (wrong shape).
  - Returns a per-record 'failed' list instead of the AWS-required
    batchItemFailures shape for partial-batch-failure reporting.
"""

import json
import os
import time
import boto3

_endpoint = os.environ.get("AWS_ENDPOINT_URL", "http://localstack:4566")
ddb = boto3.client("dynamodb", endpoint_url=_endpoint)

TABLE_NAME = os.environ.get("TABLE_NAME", "orders")


def _process_record(record):
    payload = json.loads(record["body"])
    order_id = payload["order_id"]
    merchant_id = payload["merchant_id"]
    amount = int(payload["amount"])

    ddb.put_item(
        TableName=TABLE_NAME,
        Item={
            "order_id": {"S": order_id},
            "merchant_id": {"S": merchant_id},
            "amount": {"N": str(amount)},
            "created_at": {"N": str(int(time.time()))},
        },
    )


def lambda_handler(event, context):
    failed = []
    for record in event.get("Records", []):
        try:
            _process_record(record)
        except Exception as e:
            print(f"[error] msgId={record.get('messageId')} {type(e).__name__}: {e}")
            failed.append({"itemIdentifier": record["messageId"]})

    return {"failed": failed}
PY
(cd "$WORKDIR" && zip -q handler.zip handler.py)

log "creating Lambda function"
aws lambda create-function \
  --function-name "$LAMBDA_FUNC" \
  --runtime python3.11 \
  --role "$ROLE_ARN" \
  --handler handler.lambda_handler \
  --timeout 30 \
  --memory-size 512 \
  --environment "Variables={AWS_ENDPOINT_URL=http://localstack:4566,TABLE_NAME=orders}" \
  --zip-file "fileb://${WORKDIR}/handler.zip" >/dev/null

for _ in $(seq 1 30); do
  STATE=$(aws lambda get-function --function-name "$LAMBDA_FUNC" \
    --query 'Configuration.State' --output text 2>/dev/null || echo "Pending")
  [ "$STATE" = "Active" ] && break
  sleep 1
done
log "Lambda $LAMBDA_FUNC ready"

log "done"

[stdout]
setup.sh
---
#!/bin/bash
[redacted: decontamination sentinel]
[redacted: decontamination sentinel]
#
# Pre-seeds the consumer Lambda + its role with a broken-by-design
# handler and incomplete IAM. The agent has to build everything else
# (queues, DDB, apigw, integration, deployment, ESM) AND fix this
# Lambda's handler + role. Without the pre-seeded Lambda, Opus 4.7
# tends to read the prose and forget the consumer path entirely.

set -euo pipefail

REGION="${AWS_DEFAULT_REGION:-us-east-1}"
ACCOUNT_ID="000000000000"

LAMBDA_FUNC="orders-consumer"
LAMBDA_ROLE="orders-consumer-role"

log() { echo "[setup] $*" >&2; }

log "waiting for localstack"
for _ in $(seq 1 80); do
  HEALTH=$(curl -sf http://localstack:4566/_localstack/health || true)
  echo "$HEALTH" | grep -qE '"lambda": "(available|running)"' \
    && echo "$HEALTH" | grep -qE '"iam": "(available|running)"' \
    && break
  sleep 2
done

log "creating Lambda consumer role (deliberately incomplete)"
TRUST=$(cat <<'JSON'
{
  "Version": "2012-10-17",
  "Statement": [
    {"Effect": "Allow", "Principal": {"Service": "lambda.amazonaws.com"}, "Action": "sts:AssumeRole"}
  ]
}
JSON
)
aws iam create-role \
  --role-name "$LAMBDA_ROLE" \
  --assume-role-policy-document "$TRUST" >/dev/null
aws iam attach-role-policy \
  --role-name "$LAMBDA_ROLE" \
  --policy-arn arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole
# Note: no dynamodb:PutItem, no sqs perms. Agent fixes this.
ROLE_ARN=$(aws iam get-role --role-name "$LAMBDA_ROLE" --query 'Role.Arn' --output text)

log "packaging Lambda (broken-by-design inline handler)"
WORKDIR="$(mktemp -d)"
cat > "${WORKDIR}/handler.py" <<'PY'
"""Orders consumer - broken by design.

Known issues (agent must fix):
  - Not idempotent: a duplicate message will try to PutItem again,
    which will either overwrite (wrong) or fail (wrong shape).
  - Returns a per-record 'failed' list instead of the AWS-required
    batchItemFailures shape for partial-batch-failure reporting.
"""

import json
import os
import time
import boto3

_endpoint = os.environ.get("AWS_ENDPOINT_URL", "http://localstack:4566")
ddb = boto3.client("dynamodb", endpoint_url=_endpoint)

TABLE_NAME = os.environ.get("TABLE_NAME", "orders")


def _process_record(record):
    payload = json.loads(record["body"])
    order_id = payload["order_id"]
    merchant_id = payload["merchant_id"]
    amount = int(payload["amount"])

    ddb.put_item(
        TableName=TABLE_NAME,
        Item={
            "order_id": {"S": order_id},
            "merchant_id": {"S": merchant_id},
            "amount": {"N": str(amount)},
            "created_at": {"N": str(int(time.time()))},
        },
    )


def lambda_handler(event, context):
    failed = []
    for record in event.get("Records", []):
        try:
            _process_record(record)
        except Exception as e:
            print(f"[error] msgId={record.get('messageId')} {type(e).__name__}: {e}")
            failed.append({"itemIdentifier": record["messageId"]})

    return {"failed": failed}
PY
(cd "$WORKDIR" && zip -q handler.zip handler.py)

log "creating Lambda function"
aws lambda create-function \
  --function-name "$LAMBDA_FUNC" \
  --runtime python3.11 \
  --role "$ROLE_ARN" \
  --handler handler.lambda_handler \
  --timeout 30 \
  --memory-size 512 \
  --environment "Variables={AWS_ENDPOINT_URL=http://localstack:4566,TABLE_NAME=orders}" \
  --zip-file "fileb://${WORKDIR}/handler.zip" >/dev/null

for _ in $(seq 1 30); do
  STATE=$(aws lambda get-function --function-name "$LAMBDA_FUNC" \
    --query 'Configuration.State' --output text 2>/dev/null || echo "Pending")
  [ "$STATE" = "Active" ] && break
  sleep 1
done
log "Lambda $LAMBDA_FUNC ready"

log "done"

Verify Lambda and role exist

shell
echo "=== env ===" && env | grep -i aws && echo "=== lambda ===" && aws --endpoint-url=http://localstack:4566 lambda get-function --function-name orders-consumer --query 'Configuration.{State:State,Role:Role,FunctionArn:FunctionArn}' && echo "=== role ===" && aws iam get-role --role-name orders-consumer-role --query 'Role.Arn' --output text
output
=== env ===
AWS_DEFAULT_REGION=us-east-1
AWS_PAGER=
AWS_SECRET_ACCESS_KEY=test
AWS_ACCESS_KEY_ID=test
AWS_ENDPOINT_URL=http://localstack:4566
=== lambda ===
{
    "State": "Active",
    "Role": "arn:aws:iam::000000000000:role/orders-consumer-role",
    "FunctionArn": "arn:aws:lambda:us-east-1:000000000000:function:orders-consumer"
}
=== role ===
arn:aws:iam::000000000000:role/orders-consumer-role

[stdout]
=== env ===
AWS_DEFAULT_REGION=us-east-1
AWS_PAGER=
AWS_SECRET_ACCESS_KEY=test
AWS_ACCESS_KEY_ID=test
AWS_ENDPOINT_URL=http://localstack:4566
=== lambda ===
{
    "State": "Active",
    "Role": "arn:aws:iam::000000000000:role/orders-consumer-role",
    "FunctionArn": "arn:aws:lambda:us-east-1:000000000000:function:orders-consumer"
}
=== role ===
arn:aws:iam::000000000000:role/orders-consumer-role
Good. Lambda and role exist. AWS_ENDPOINT_URL is exported, so all aws/boto3 calls hit localstack. Let me build everything in dependency order.

Create DynamoDB orders table

shell
set -e
echo "=== Creating DynamoDB table ==="
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 >/dev/null

aws dynamodb wait table-exists --table-name orders
echo "table ready"
output
=== Creating DynamoDB table ===
table ready

[stdout]
=== Creating DynamoDB table ===
table ready

Create FIFO queues with redrive

shell
set -e
echo "=== Creating DLQ FIFO ==="
DLQ_URL=$(aws sqs create-queue \
  --queue-name orders-dlq.fifo \
  --attributes '{"FifoQueue":"true","ContentBasedDeduplication":"false"}' \
  --query 'QueueUrl' --output text)
echo "DLQ_URL=$DLQ_URL"

DLQ_ARN=$(aws sqs get-queue-attributes \
  --queue-url "$DLQ_URL" \
  --attribute-names QueueArn \
  --query 'Attributes.QueueArn' --output text)
echo "DLQ_ARN=$DLQ_ARN"

echo "=== Creating main FIFO with redrive ==="
REDRIVE=$(jq -nc --arg arn "$DLQ_ARN" '{deadLetterTargetArn:$arn,maxReceiveCount:"3"}')
MAIN_URL=$(aws sqs create-queue \
  --queue-name orders.fifo \
  --attributes "{\"FifoQueue\":\"true\",\"ContentBasedDeduplication\":\"false\",\"RedrivePolicy\":${REDRIVE}}" \
  --query 'QueueUrl' --output text)
echo "MAIN_URL=$MAIN_URL"

MAIN_ARN=$(aws sqs get-queue-attributes \
  --queue-url "$MAIN_URL" \
  --attribute-names QueueArn \
  --query 'Attributes.QueueArn' --output text)
echo "MAIN_ARN=$MAIN_ARN"

# Save for later steps
echo "$MAIN_URL" > /tmp/main_url
echo "$MAIN_ARN" > /tmp/main_arn
echo "$DLQ_URL" > /tmp/dlq_url
echo "$DLQ_ARN" > /tmp/dlq_arn
output
=== Creating DLQ FIFO ===
DLQ_URL=http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/orders-dlq.fifo
DLQ_ARN=arn:aws:sqs:us-east-1:000000000000:orders-dlq.fifo
=== Creating main FIFO with redrive ===

aws: [ERROR]: An error occurred (ParamValidation): Parameter validation failed:
Invalid type for parameter Attributes.RedrivePolicy, value: OrderedDict({'deadLetterTargetArn': 'arn:aws:sqs:us-east-1:000000000000:orders-dlq.fifo', 'maxReceiveCount': '3'}), type: <class 'collections.OrderedDict'>, valid types: <class 'str'>
MAIN_URL=

aws: [ERROR]: An error occurred (AWS.SimpleQueueService.NonExistentQueue) when calling the GetQueueAttributes operation: The specified queue does not exist.
MAIN_ARN=

[stdout]
=== Creating DLQ FIFO ===
DLQ_URL=http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/orders-dlq.fifo
DLQ_ARN=arn:aws:sqs:us-east-1:000000000000:orders-dlq.fifo
=== Creating main FIFO with redrive ===

aws: [ERROR]: An error occurred (ParamValidation): Parameter validation failed:
Invalid type for parameter Attributes.RedrivePolicy, value: OrderedDict({'deadLetterTargetArn': 'arn:aws:sqs:us-east-1:000000000000:orders-dlq.fifo', 'maxReceiveCount': '3'}), type: <class 'collections.OrderedDict'>, valid types: <class 'str'>
MAIN_URL=

aws: [ERROR]: An error occurred (AWS.SimpleQueueService.NonExistentQueue) when calling the GetQueueAttributes operation: The specified queue does not exist.
MAIN_ARN=

Create main FIFO with redrive (JSON-encoded string)

shell
set -e
DLQ_ARN=$(cat /tmp/dlq_arn)
# RedrivePolicy must itself be a JSON-encoded STRING within the attributes object
ATTRS=$(jq -nc \
  --arg arn "$DLQ_ARN" \
  '{FifoQueue:"true",ContentBasedDeduplication:"false",RedrivePolicy:({deadLetterTargetArn:$arn,maxReceiveCount:"3"}|tostring)}')
echo "ATTRS=$ATTRS"

MAIN_URL=$(aws sqs create-queue \
  --queue-name orders.fifo \
  --attributes "$ATTRS" \
  --query 'QueueUrl' --output text)
echo "MAIN_URL=$MAIN_URL"

MAIN_ARN=$(aws sqs get-queue-attributes \
  --queue-url "$MAIN_URL" \
  --attribute-names QueueArn \
  --query 'Attributes.QueueArn' --output text)
echo "MAIN_ARN=$MAIN_ARN"

echo "$MAIN_URL" > /tmp/main_url
echo "$MAIN_ARN" > /tmp/main_arn

# Verify redrive applied
aws sqs get-queue-attributes \
  --queue-url "$MAIN_URL" \
  --attribute-names FifoQueue ContentBasedDeduplication RedrivePolicy
output
ATTRS={"FifoQueue":"true","ContentBasedDeduplication":"false","RedrivePolicy":"{\"deadLetterTargetArn\":\"arn:aws:sqs:us-east-1:000000000000:orders-dlq.fifo\",\"maxReceiveCount\":\"3\"}"}
MAIN_URL=http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/orders.fifo
MAIN_ARN=arn:aws:sqs:us-east-1:000000000000:orders.fifo
{
    "Attributes": {
        "FifoQueue": "true",
        "ContentBasedDeduplication": "false",
        "RedrivePolicy": "{\"deadLetterTargetArn\":\"arn:aws:sqs:us-east-1:000000000000:orders-dlq.fifo\",\"maxReceiveCount\":\"3\"}"
    }
}

[stdout]
ATTRS={"FifoQueue":"true","ContentBasedDeduplication":"false","RedrivePolicy":"{\"deadLetterTargetArn\":\"arn:aws:sqs:us-east-1:000000000000:orders-dlq.fifo\",\"maxReceiveCount\":\"3\"}"}
MAIN_URL=http://sqs.us-east-1.localhost.localstack.cloud:4566/000000000000/orders.fifo
MAIN_ARN=arn:aws:sqs:us-east-1:000000000000:orders.fifo
{
    "Attributes": {
        "FifoQueue": "true",
        "ContentBasedDeduplication": "false",
        "RedrivePolicy": "{\"deadLetterTargetArn\":\"arn:aws:sqs:us-east-1:000000000000:orders-dlq.fifo\",\"maxReceiveCount\":\"3\"}"
    }
}
Queues set up with redrive. Now fix the Lambda role permissions and replace the handler.

Add DDB+SQS permissions to consumer role

shell
set -e
echo "=== Attaching DDB + SQS perms to consumer role ==="
POLICY=$(cat <<'JSON'
{
  "Version":"2012-10-17",
  "Statement":[
    {
      "Effect":"Allow",
      "Action":[
        "dynamodb:PutItem",
        "dynamodb:GetItem",
        "dynamodb:UpdateItem",
        "dynamodb:DescribeTable"
      ],
      "Resource":"arn:aws:dynamodb:us-east-1:000000000000:table/orders"
    },
    {
      "Effect":"Allow",
      "Action":[
        "sqs:ReceiveMessage",
        "sqs:DeleteMessage",
        "sqs:GetQueueAttributes",
        "sqs:ChangeMessageVisibility"
      ],
      "Resource":"arn:aws:sqs:us-east-1:000000000000:orders.fifo"
    }
  ]
}
JSON
)

aws iam put-role-policy \
  --role-name orders-consumer-role \
  --policy-name orders-consumer-inline \
  --policy-document "$POLICY"
echo "policy attached"
aws iam list-role-policies --role-name orders-consumer-role
aws iam list-attached-role-policies --role-name orders-consumer-role
output
=== Attaching DDB + SQS perms to consumer role ===
policy attached
{
    "PolicyNames": [
        "orders-consumer-inline"
    ]
}
{
    "AttachedPolicies": [
        {
            "PolicyName": "AWSLambdaBasicExecutionRole",
            "PolicyArn": "arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole"
        }
    ]
}

[stdout]
=== Attaching DDB + SQS perms to consumer role ===
policy attached
{
    "PolicyNames": [
        "orders-consumer-inline"
    ]
}
{
    "AttachedPolicies": [
        {
            "PolicyName": "AWSLambdaBasicExecutionRole",
            "PolicyArn": "arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole"
        }
    ]
}
ToolSearch
{
  "query": "select:TodoWrite",
  "max_results": 1
}

, output, 
{"type": "tool_reference", "tool_name": "TodoWrite"}
  • Create DDB table
  • Create FIFO queues with redrive
  • Fix consumer Lambda role permissions
  • Replace Lambda handler (idempotent + correct batchItemFailures)
  • Create event source mapping main queue → Lambda
  • Create REST API + resource + method + AWS-service SQS integration
  • Create apigw→sqs role and policy
  • Deploy stage dev
  • End-to-end verify
write · /tmp/lambda/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")
ddb = boto3.client("dynamodb", endpoint_url=_endpoint)

TABLE_NAME = os.environ.get("TABLE_NAME", "orders")


def _process_record(record):
    payload = json.loads(record["body"])
    order_id = str(payload["order_id"])
    merchant_id = str(payload["merchant_id"])
    amount = int(payload["amount"])

    try:
        ddb.put_item(
            TableName=TABLE_NAME,
            Item={
                "order_id": {"S": order_id},
                "merchant_id": {"S": merchant_id},
                "amount": {"N": str(amount)},
                "created_at": {"N": str(int(time.time()))},
            },
            ConditionExpression="attribute_not_exists(order_id)",
        )
    except ClientError as e:
        if e.response.get("Error", {}).get("Code") == "ConditionalCheckFailedException":
            return
        raise


def lambda_handler(event, context):
    failures = []
    for record in event.get("Records", []):
        try:
            _process_record(record)
        except Exception as e:
            print(f"[error] msgId={record.get('messageId')} {type(e).__name__}: {e}")
            failures.append({"itemIdentifier": record["messageId"]})

    return {"batchItemFailures": failures}

Package and update Lambda code

shell
set -e
cd /tmp/lambda && zip -q handler.zip handler.py
aws lambda update-function-code \
  --function-name orders-consumer \
  --zip-file fileb:///tmp/lambda/handler.zip \
  --query '{State:State,LastUpdateStatus:LastUpdateStatus}' >/dev/null

# Wait for update
for i in $(seq 1 30); do
  STATUS=$(aws lambda get-function --function-name orders-consumer \
    --query 'Configuration.LastUpdateStatus' --output text)
  STATE=$(aws lambda get-function --function-name orders-consumer \
    --query 'Configuration.State' --output text)
  [ "$STATUS" = "Successful" ] && [ "$STATE" = "Active" ] && break
  sleep 1
done
echo "lambda updated: state=$STATE status=$STATUS"
output
lambda updated: state=Active status=Successful
Shell cwd was reset to /app

[stdout]
lambda updated: state=Active status=Successful
[stderr]

Shell cwd was reset to /app

Create event source mapping with ReportBatchItemFailures

shell
set -e
MAIN_ARN=$(cat /tmp/main_arn)
echo "=== Creating event source mapping ==="
aws lambda create-event-source-mapping \
  --function-name orders-consumer \
  --event-source-arn "$MAIN_ARN" \
  --batch-size 10 \
  --function-response-types ReportBatchItemFailures \
  --enabled \
  --query '{UUID:UUID,State:State}' >/dev/null

# wait for ESM to become Enabled
for i in $(seq 1 30); do
  ST=$(aws lambda list-event-source-mappings \
    --function-name orders-consumer \
    --event-source-arn "$MAIN_ARN" \
    --query 'EventSourceMappings[0].State' --output text)
  [ "$ST" = "Enabled" ] && break
  sleep 1
done
aws lambda list-event-source-mappings \
  --function-name orders-consumer \
  --event-source-arn "$MAIN_ARN" \
  --query 'EventSourceMappings[0].{State:State,FunctionResponseTypes:FunctionResponseTypes,BatchSize:BatchSize}'
output
=== Creating event source mapping ===
{
    "State": "Enabled",
    "FunctionResponseTypes": [
        "ReportBatchItemFailures"
    ],
    "BatchSize": 10
}

[stdout]
=== Creating event source mapping ===
{
    "State": "Enabled",
    "FunctionResponseTypes": [
        "ReportBatchItemFailures"
    ],
    "BatchSize": 10
}
Now the API Gateway side. Create the role first, then REST API.

Create apigw-to-sqs role with SendMessage policy

shell
set -e
echo "=== Creating apigw->sqs role ==="
TRUST=$(cat <<'JSON'
{
  "Version":"2012-10-17",
  "Statement":[
    {"Effect":"Allow","Principal":{"Service":"apigateway.amazonaws.com"},"Action":"sts:AssumeRole"}
  ]
}
JSON
)
aws iam create-role \
  --role-name apigw-to-sqs-role \
  --assume-role-policy-document "$TRUST" >/dev/null

POLICY=$(cat <<'JSON'
{
  "Version":"2012-10-17",
  "Statement":[
    {
      "Effect":"Allow",
      "Action":["sqs:SendMessage","sqs:GetQueueUrl","sqs:GetQueueAttributes"],
      "Resource":"arn:aws:sqs:us-east-1:000000000000:orders.fifo"
    },
    {
      "Effect":"Allow",
      "Action":["logs:CreateLogGroup","logs:CreateLogStream","logs:PutLogEvents"],
      "Resource":"*"
    }
  ]
}
JSON
)
aws iam put-role-policy \
  --role-name apigw-to-sqs-role \
  --policy-name apigw-sqs-inline \
  --policy-document "$POLICY"

APIGW_ROLE_ARN=$(aws iam get-role --role-name apigw-to-sqs-role --query 'Role.Arn' --output text)
echo "APIGW_ROLE_ARN=$APIGW_ROLE_ARN"
echo "$APIGW_ROLE_ARN" > /tmp/apigw_role_arn
output
=== Creating apigw->sqs role ===
APIGW_ROLE_ARN=arn:aws:iam::000000000000:role/apigw-to-sqs-role

[stdout]
=== Creating apigw->sqs role ===
APIGW_ROLE_ARN=arn:aws:iam::000000000000:role/apigw-to-sqs-role

Create REST API, /orders resource, POST method

shell
set -e
echo "=== Creating REST API ==="
API_ID=$(aws apigateway create-rest-api \
  --name orders-api \
  --query 'id' --output text)
echo "API_ID=$API_ID"
echo "$API_ID" > /tmp/api_id

ROOT_ID=$(aws apigateway get-resources \
  --rest-api-id "$API_ID" \
  --query 'items[?path==`/`].id' --output text)
echo "ROOT_ID=$ROOT_ID"

ORDERS_ID=$(aws apigateway create-resource \
  --rest-api-id "$API_ID" \
  --parent-id "$ROOT_ID" \
  --path-part orders \
  --query 'id' --output text)
echo "ORDERS_ID=$ORDERS_ID"
echo "$ORDERS_ID" > /tmp/orders_id

echo "=== POST method ==="
aws apigateway put-method \
  --rest-api-id "$API_ID" \
  --resource-id "$ORDERS_ID" \
  --http-method POST \
  --authorization-type NONE >/dev/null
echo "method created"
output
=== Creating REST API ===
API_ID=moy8iwefwm
ROOT_ID=m2yllllsbo
ORDERS_ID=itn2hsou8j
=== POST method ===
method created

[stdout]
=== Creating REST API ===
API_ID=moy8iwefwm
ROOT_ID=m2yllllsbo
ORDERS_ID=itn2hsou8j
=== POST method ===
method created

Wire AWS-service SQS integration with mapping template

shell
set -e
API_ID=$(cat /tmp/api_id)
ORDERS_ID=$(cat /tmp/orders_id)
APIGW_ROLE_ARN=$(cat /tmp/apigw_role_arn)
REGION=us-east-1
ACCOUNT=000000000000
QUEUE_NAME=orders.fifo

# Mapping template: form-encoded SQS SendMessage call.
# FIFO requires MessageGroupId; content-based dedup is OFF so we also set MessageDeduplicationId.
TEMPLATE='Action=SendMessage&MessageBody=$util.urlEncode($input.body)&MessageGroupId=$util.urlEncode($input.path('"'"'$.order_id'"'"'))&MessageDeduplicationId=$util.urlEncode($input.path('"'"'$.order_id'"'"'))'
echo "Template: $TEMPLATE"

REQ_TEMPLATES=$(jq -nc --arg t "$TEMPLATE" '{"application/json":$t}')

echo "=== put-integration ==="
aws apigateway put-integration \
  --rest-api-id "$API_ID" \
  --resource-id "$ORDERS_ID" \
  --http-method POST \
  --type AWS \
  --integration-http-method POST \
  --uri "arn:aws:apigateway:${REGION}:sqs:path/${ACCOUNT}/${QUEUE_NAME}" \
  --credentials "$APIGW_ROLE_ARN" \
  --request-parameters '{"integration.request.header.Content-Type":"'"'"'application/x-www-form-urlencoded'"'"'"}' \
  --request-templates "$REQ_TEMPLATES" \
  --passthrough-behavior NEVER >/dev/null
echo "integration created"

echo "=== method response 200 ==="
aws apigateway put-method-response \
  --rest-api-id "$API_ID" \
  --resource-id "$ORDERS_ID" \
  --http-method POST \
  --status-code 200 \
  --response-models '{"application/json":"Empty"}' >/dev/null

echo "=== integration response 200 ==="
aws apigateway put-integration-response \
  --rest-api-id "$API_ID" \
  --resource-id "$ORDERS_ID" \
  --http-method POST \
  --status-code 200 \
  --response-templates '{"application/json":"{\"ok\":true}"}' >/dev/null
echo "responses created"
output
Template: Action=SendMessage&MessageBody=$util.urlEncode($input.body)&MessageGroupId=$util.urlEncode($input.path('$.order_id'))&MessageDeduplicationId=$util.urlEncode($input.path('$.order_id'))
=== put-integration ===
integration created
=== method response 200 ===
=== integration response 200 ===
responses created

[stdout]
Template: Action=SendMessage&MessageBody=$util.urlEncode($input.body)&MessageGroupId=$util.urlEncode($input.path('$.order_id'))&MessageDeduplicationId=$util.urlEncode($input.path('$.order_id'))
=== put-integration ===
integration created
=== method response 200 ===
=== integration response 200 ===
responses created

Create initial deployment to dev stage

shell
set -e
API_ID=$(cat /tmp/api_id)
echo "=== Deploying stage dev ==="
aws apigateway create-deployment \
  --rest-api-id "$API_ID" \
  --stage-name dev \
  --query '{id:id,createdDate:createdDate}' >/dev/null
echo "deployed"

aws apigateway get-stage --rest-api-id "$API_ID" --stage-name dev \
  --query '{stage:stageName,deploymentId:deploymentId}'
output
=== Deploying stage dev ===
deployed
{
    "stage": "dev",
    "deploymentId": "knvsws5spv"
}

[stdout]
=== Deploying stage dev ===
deployed
{
    "stage": "dev",
    "deploymentId": "knvsws5spv"
}
  • Create DDB table
  • Create FIFO queues with redrive
  • Fix consumer Lambda role permissions
  • Replace Lambda handler
  • Create event source mapping main queue → Lambda
  • Create REST API + resource + method + integration
  • Create apigw→sqs role and policy
  • Deploy stage dev
  • End-to-end verify
Now an end-to-end test from inside the compose network. The verifier hits via http://localstack , the API Gateway invoke URL on localstack is `http://<api>.execute-api.localhost.localstack.cloud:4566/dev/orders` or `http://localstack:4566/restapis/<id>/dev/_user_request_/orders`. Let me try both forms.

First end-to-end POST and verify

shell
set -e
API_ID=$(cat /tmp/api_id)
URL="http://localstack:4566/restapis/${API_ID}/dev/_user_request_/orders"
echo "URL=$URL"

echo "=== POST 1 (order o-1) ==="
curl -sS -i -X POST "$URL" \
  -H 'Content-Type: application/json' \
  -d '{"order_id":"o-1","merchant_id":"m-1","amount":100}'
echo
echo "=== sleep, then check DDB ==="
sleep 5
aws dynamodb scan --table-name orders --query 'Items'
echo "=== DLQ depth ==="
DLQ_URL=$(cat /tmp/dlq_url)
aws sqs get-queue-attributes --queue-url "$DLQ_URL" --attribute-names ApproximateNumberOfMessages
output
URL=http://localstack:4566/restapis/moy8iwefwm/dev/_user_request_/orders
=== POST 1 (order o-1) ===
HTTP/1.1 200 OK
Server: TwistedWeb/24.3.0
Date: Tue, 28 Apr 2026 13:44:14 GMT
Content-Type: application/json
Connection: keep-alive
Content-Length: 11
x-amzn-RequestId: 18ff2001-a6c5-4d4b-9959-5822adfd8bf3
x-amz-apigw-id: e9eedbbd=
X-Amzn-Trace-Id: Root=1-69f0b9ae-c05d63c3b11570f7fc7df8cb;Parent=8e7ad6411d8d97b9;Sampled=0
x-localstack: true

{"ok":true}
=== sleep, then check DDB ===
[]
=== DLQ depth ===
{
    "Attributes": {
        "ApproximateNumberOfMessages": "0"
    }
}

[stdout]
URL=http://localstack:4566/restapis/moy8iwefwm/dev/_user_request_/orders
=== POST 1 (order o-1) ===
HTTP/1.1 200 OK
Server: TwistedWeb/24.3.0
Date: Tue, 28 Apr 2026 13:44:14 GMT
Content-Type: application/json
Connection: keep-alive
Content-Length: 11
x-amzn-RequestId: 18ff2001-a6c5-4d4b-9959-5822adfd8bf3
x-amz-apigw-id: e9eedbbd=
X-Amzn-Trace-Id: Root=1-69f0b9ae-c05d63c3b11570f7fc7df8cb;Parent=8e7ad6411d8d97b9;Sampled=0
x-localstack: true

{"ok":true}
=== sleep, then check DDB ===
[]
=== DLQ depth ===
{
    "Attributes": {
        "ApproximateNumberOfMessages": "0"
    }
}
HTTP 200 returned but DDB empty. Need to debug , message might be stuck in queue or Lambda errored.

Inspect queue, ESM and lambda logs

shell
set -e
MAIN_URL=$(cat /tmp/main_url)
echo "=== main queue depth ==="
aws sqs get-queue-attributes --queue-url "$MAIN_URL" \
  --attribute-names ApproximateNumberOfMessages ApproximateNumberOfMessagesNotVisible ApproximateNumberOfMessagesDelayed

echo "=== ESM state ==="
MAIN_ARN=$(cat /tmp/main_arn)
aws lambda list-event-source-mappings \
  --function-name orders-consumer \
  --event-source-arn "$MAIN_ARN"

echo "=== Lambda log groups ==="
aws logs describe-log-groups --log-group-name-prefix "/aws/lambda/orders-consumer"
echo "=== Lambda log events (recent) ==="
aws logs describe-log-streams \
  --log-group-name "/aws/lambda/orders-consumer" \
  --order-by LastEventTime --descending --max-items 3 2>&1 | head -50 || echo "no log group yet"
output
=== main queue depth ===
{
    "Attributes": {
        "ApproximateNumberOfMessages": "0",
        "ApproximateNumberOfMessagesNotVisible": "0",
        "ApproximateNumberOfMessagesDelayed": "0"
    }
}
=== ESM state ===
{
    "EventSourceMappings": [
        {
            "UUID": "1bbfc13a-7cd9-45ac-9fa5-f6e9cbdd2509",
            "BatchSize": 10,
            "MaximumBatchingWindowInSeconds": 0,
            "EventSourceArn": "arn:aws:sqs:us-east-1:000000000000:orders.fifo",
            "FunctionArn": "arn:aws:lambda:us-east-1:000000000000:function:orders-consumer",
            "LastModified": "2026-04-28T13:43:09.407945+00:00",
            "State": "Enabled",
            "StateTransitionReason": "USER_INITIATED",
            "FunctionResponseTypes": [
                "ReportBatchItemFailures"
            ],
            "EventSourceMappingArn": "arn:aws:lambda:us-east-1:000000000000:event-source-mapping:1bbfc13a-7cd9-45ac-9fa5-f6e9cbdd2509"
        }
    ]
}
=== Lambda log groups ===
{
    "logGroups": [
        {
            "logGroupName": "/aws/lambda/orders-consumer",
            "creationTime": 1777383860137,
            "metricFilterCount": 0,
            "arn": "arn:aws:logs:us-east-1:000000000000:log-group:/aws/lambda/orders-consumer:*",
            "storedBytes": 267,
            "logGroupClass": "STANDARD",
            "logGroupArn": "arn:aws:logs:us-east-1:000000000000:log-group:/aws/lambda/orders-consumer"
        }
    ]
}
=== Lambda log events (recent) ===
{
    "logStreams": [
        {
            "logStreamName": "2026/04/28/[$LATEST]756e3f9ad0c220bf2eca03cb9e8f4a17",
            "creationTime": 1777383860140,
            "firstEventTimestamp": 1777383859991,
            "lastEventTimestamp": 1777383859991,
            "lastIngestionTime": 1777383860142,
            "uploadSequenceToken": "1",
            "arn": "arn:aws:logs:us-east-1:000000000000:log-group:/aws/lambda/orders-consumer:log-stream:2026/04/28/[$LATEST]756e3f9ad0c220bf2eca03cb9e8f4a17",
            "storedBytes": 267
        }
    ]
}

[stdout]
=== main queue depth ===
{
    "Attributes": {
        "ApproximateNumberOfMessages": "0",
        "ApproximateNumberOfMessagesNotVisible": "0",
        "ApproximateNumberOfMessagesDelayed": "0"
    }
}
=== ESM state ===
{
    "EventSourceMappings": [
        {
            "UUID": "1bbfc13a-7cd9-45ac-9fa5-f6e9cbdd2509",
            "BatchSize": 10,
            "MaximumBatchingWindowInSeconds": 0,
            "EventSourceArn": "arn:aws:sqs:us-east-1:000000000000:orders.fifo",
            "FunctionArn": "arn:aws:lambda:us-east-1:000000000000:function:orders-consumer",
            "LastModified": "2026-04-28T13:43:09.407945+00:00",
            "State": "Enabled",
            "StateTransitionReason": "USER_INITIATED",
            "FunctionResponseTypes": [
                "ReportBatchItemFailures"
            ],
            "EventSourceMappingArn": "arn:aws:lambda:us-east-1:000000000000:event-source-mapping:1bbfc13a-7cd9-45ac-9fa5-f6e9cbdd2509"
        }
    ]
}
=== Lambda log groups ===
{
    "logGroups": [
        {
            "logGroupName": "/aws/lambda/orders-consumer",
            "creationTime": 1777383860137,
            "metricFilterCount": 0,
            "arn": "arn:aws:logs:us-east-1:000000000000:log-group:/aws/lambda/orders-consumer:*",
            "storedBytes": 267,
            "logGroupClass": "STANDARD",
            "logGroupArn": "arn:aws:logs:us-east-1:000000000000:log-group:/aws/lambda/orders-consumer"
        }
    ]
}
=== Lambda log events (recent) ===
{
    "logStreams": [
        {
            "logStreamName": "2026/04/28/[$LATEST]756e3f9ad0c220bf2eca03cb9e8f4a17",
            "creationTime": 1777383860140,
            "firstEventTimestamp": 1777383859991,
            "lastEventTimestamp": 1777383859991,
            "lastIngestionTime": 1777383860142,
            "uploadSequenceToken": "1",
            "arn": "arn:aws:logs:us-east-1:000000000000:log-group:/aws/lambda/orders-consumer:log-stream:2026/04/28/[$LATEST]756e3f9ad0c220bf2eca03cb9e8f4a17",
            "storedBytes": 267
        }
    ]
}

Read Lambda log events

shell
set -e
aws logs get-log-events \
  --log-group-name "/aws/lambda/orders-consumer" \
  --log-stream-name "2026/04/28/[\$LATEST]756e3f9ad0c220bf2eca03cb9e8f4a17" \
  --limit 50 \
  --query 'events[*].message' --output text
output
START RequestId: 294e10a4-9546-42c9-8366-3c5a88b77128 Version: $LATEST
	END RequestId: 294e10a4-9546-42c9-8366-3c5a88b77128
	REPORT RequestId: 294e10a4-9546-42c9-8366-3c5a88b77128	Duration: 161.24 ms	Billed Duration: 162 ms	Memory Size: 512 MB	Max Memory Used: 512 MB

[stdout]
START RequestId: 294e10a4-9546-42c9-8366-3c5a88b77128 Version: $LATEST
	END RequestId: 294e10a4-9546-42c9-8366-3c5a88b77128
	REPORT RequestId: 294e10a4-9546-42c9-8366-3c5a88b77128	Duration: 161.24 ms	Billed Duration: 162 ms	Memory Size: 512 MB	Max Memory Used: 512 MB

Re-check DDB

shell
set -e
echo "=== rescan DDB orders ==="
aws dynamodb scan --table-name orders
echo
echo "=== get-item directly ==="
aws dynamodb get-item --table-name orders --key '{"order_id":{"S":"o-1"}}'
output
=== rescan DDB orders ===
{
    "Items": [
        {
            "created_at": {
                "N": "1777383859"
            },
            "amount": {
                "N": "100"
            },
            "merchant_id": {
                "S": "m-1"
            },
            "order_id": {
                "S": "o-1"
            }
        }
    ],
    "Count": 1,
    "ScannedCount": 1,
    "ConsumedCapacity": null
}

=== get-item directly ===
{
    "Item": {
        "created_at": {
            "N": "1777383859"
        },
        "amount": {
            "N": "100"
        },
        "merchant_id": {
            "S": "m-1"
        },
        "order_id": {
            "S": "o-1"
        }
    }
}

[stdout]
=== rescan DDB orders ===
{
    "Items": [
        {
            "created_at": {
                "N": "1777383859"
            },
            "amount": {
                "N": "100"
            },
            "merchant_id": {
                "S": "m-1"
            },
            "order_id": {
                "S": "o-1"
            }
        }
    ],
    "Count": 1,
    "ScannedCount": 1,
    "ConsumedCapacity": null
}

=== get-item directly ===
{
    "Item": {
        "created_at": {
            "N": "1777383859"
        },
        "amount": {
            "N": "100"
        },
        "merchant_id": {
            "S": "m-1"
        },
        "order_id": {
            "S": "o-1"
        }
    }
}
The first scan was simply too soon. Now let me run the full verification: re-POST same body (idempotency) then a different order.

Full verification: idempotency, ordering, DLQ empty

shell
set -e
API_ID=$(cat /tmp/api_id)
URL="http://localstack:4566/restapis/${API_ID}/dev/_user_request_/orders"
DLQ_URL=$(cat /tmp/dlq_url)
MAIN_URL=$(cat /tmp/main_url)

echo "=== capture original created_at ==="
ORIG=$(aws dynamodb get-item --table-name orders --key '{"order_id":{"S":"o-1"}}' --query 'Item.created_at.N' --output text)
echo "ORIG created_at=$ORIG"

echo "=== POST 2: same order_id (should be idempotent no-op) ==="
sleep 2  # ensure timestamp would differ if put_item ran
curl -sS -o /dev/null -w "HTTP %{http_code}\n" -X POST "$URL" \
  -H 'Content-Type: application/json' \
  -d '{"order_id":"o-1","merchant_id":"m-1","amount":100}'

sleep 8

echo "=== verify same row, unchanged created_at ==="
aws dynamodb scan --table-name orders --query 'Items'
NEW=$(aws dynamodb get-item --table-name orders --key '{"order_id":{"S":"o-1"}}' --query 'Item.created_at.N' --output text)
echo "NEW created_at=$NEW"
[ "$ORIG" = "$NEW" ] && echo "IDEMPOTENT OK (created_at unchanged)" || echo "FAIL: created_at changed"

echo
echo "=== POST 3 + 4: two different orders same merchant ==="
curl -sS -o /dev/null -w "HTTP %{http_code}\n" -X POST "$URL" \
  -H 'Content-Type: application/json' \
  -d '{"order_id":"o-2","merchant_id":"m-1","amount":50}'
sleep 1
curl -sS -o /dev/null -w "HTTP %{http_code}\n" -X POST "$URL" \
  -H 'Content-Type: application/json' \
  -d '{"order_id":"o-3","merchant_id":"m-1","amount":75}'

sleep 8

echo "=== final scan ==="
aws dynamodb scan --table-name orders --query 'Items[*].{order_id:order_id.S,merchant_id:merchant_id.S,amount:amount.N,created_at:created_at.N}'

echo "=== queue depths (main, dlq) ==="
aws sqs get-queue-attributes --queue-url "$MAIN_URL" --attribute-names ApproximateNumberOfMessages ApproximateNumberOfMessagesNotVisible --query 'Attributes'
aws sqs get-queue-attributes --queue-url "$DLQ_URL" --attribute-names ApproximateNumberOfMessages --query 'Attributes'
output
=== capture original created_at ===
ORIG created_at=1777383859
=== POST 2: same order_id (should be idempotent no-op) ===
HTTP 200
=== verify same row, unchanged created_at ===
[
    {
        "created_at": {
            "N": "1777383859"
        },
        "amount": {
            "N": "100"
        },
        "merchant_id": {
            "S": "m-1"
        },
        "order_id": {
            "S": "o-1"
        }
    }
]
NEW created_at=1777383859
IDEMPOTENT OK (created_at unchanged)

=== POST 3 + 4: two different orders same merchant ===
HTTP 200
HTTP 200
=== final scan ===
[
    {
        "order_id": "o-1",
        "merchant_id": "m-1",
        "amount": "100",
        "created_at": "1777383859"
    },
    {
        "order_id": "o-3",
        "merchant_id": "m-1",
        "amount": "75",
        "created_at": "1777383921"
    },
    {
        "order_id": "o-2",
        "merchant_id": "m-1",
        "amount": "50",
        "created_at": "1777383919"
    }
]
=== queue depths (main, dlq) ===
{
    "ApproximateNumberOfMessages": "0",
    "ApproximateNumberOfMessagesNotVisible": "0"
}
{
    "ApproximateNumberOfMessages": "0"
}

[stdout]
=== capture original created_at ===
ORIG created_at=1777383859
=== POST 2: same order_id (should be idempotent no-op) ===
HTTP 200
=== verify same row, unchanged created_at ===
[
    {
        "created_at": {
            "N": "1777383859"
        },
        "amount": {
            "N": "100"
        },
        "merchant_id": {
            "S": "m-1"
        },
        "order_id": {
            "S": "o-1"
        }
    }
]
NEW created_at=1777383859
IDEMPOTENT OK (created_at unchanged)

=== POST 3 + 4: two different orders same merchant ===
HTTP 200
HTTP 200
=== final scan ===
[
    {
        "order_id": "o-1",
        "merchant_id": "m-1",
        "amount": "100",
        "created_at": "1777383859"
    },
    {
        "order_id": "o-3",
        "merchant_id": "m-1",
        "amount": "75",
        "created_at": "1777383921"
    },
    {
        "order_id": "o-2",
        "merchant_id": "m-1",
        "amount": "50",
        "created_at": "1777383919"
    }
]
=== queue depths (main, dlq) ===
{
    "ApproximateNumberOfMessages": "0",
    "ApproximateNumberOfMessagesNotVisible": "0"
}
{
    "ApproximateNumberOfMessages": "0"
}
All checks pass: - POST returns HTTP 200 - `o-1` row exists, `created_at=1777383859` unchanged after the duplicate POST → idempotent - `o-2` (`created_at=1777383919`) precedes `o-3` (`created_at=1777383921`) → FIFO order preserved across the same merchant_id (since I use order_id as the message group ID, ordering is per-order; the timestamp ordering proves consumer processed in the order posted) - Main queue and DLQ both empty
  • Create DDB table
  • Create FIFO queues with redrive
  • Fix consumer Lambda role permissions
  • Replace Lambda handler
  • Create event source mapping
  • Create REST API + resource + method + integration
  • Create apigw→sqs role and policy
  • Deploy stage dev
  • End-to-end verify
Re-reading: "two different order_ids under the same merchant preserve posted order". That requires the **merchant_id** to be the FIFO group, not the order_id. Per-order grouping wouldn't guarantee cross-order ordering within a merchant. Let me fix the mapping template.

Switch MessageGroupId to merchant_id and redeploy

shell
set -e
API_ID=$(cat /tmp/api_id)
ORDERS_ID=$(cat /tmp/orders_id)

TEMPLATE='Action=SendMessage&MessageBody=$util.urlEncode($input.body)&MessageGroupId=$util.urlEncode($input.path('"'"'$.merchant_id'"'"'))&MessageDeduplicationId=$util.urlEncode($input.path('"'"'$.order_id'"'"'))'
echo "Template: $TEMPLATE"

# update the integration's request templates only
aws apigateway update-integration \
  --rest-api-id "$API_ID" \
  --resource-id "$ORDERS_ID" \
  --http-method POST \
  --patch-operations \
    "op=replace,path=/requestTemplates/application~1json,value=$TEMPLATE" >/dev/null

echo "=== verify integration ==="
aws apigateway get-integration \
  --rest-api-id "$API_ID" \
  --resource-id "$ORDERS_ID" \
  --http-method POST \
  --query 'requestTemplates'

echo "=== redeploy stage dev ==="
aws apigateway create-deployment --rest-api-id "$API_ID" --stage-name dev \
  --query '{id:id}' >/dev/null
echo "redeployed"
output
Template: Action=SendMessage&MessageBody=$util.urlEncode($input.body)&MessageGroupId=$util.urlEncode($input.path('$.merchant_id'))&MessageDeduplicationId=$util.urlEncode($input.path('$.order_id'))

aws: [ERROR]: An error occurred (ParamValidation): Error parsing parameter '--patch-operations': Expected: ',', received: ''' for input:
 op=replace,path=/requestTemplates/application~1json,value=Action=SendMessage&MessageBody=$util.urlEncode($input.body)&MessageGroupId=$util.urlEncode($input.path('$.merchant_id'))&MessageDeduplicationId=$util.urlEncode($input.path('$.order_id'))
                                                                                                                                                                 ^
=== verify integration ===
{
    "application/json": "Action=SendMessage&MessageBody=$util.urlEncode($input.body)&MessageGroupId=$util.urlEncode($input.path('$.order_id'))&MessageDeduplicationId=$util.urlEncode($input.path('$.order_id'))"
}
=== redeploy stage dev ===
redeployed

[stdout]
Template: Action=SendMessage&MessageBody=$util.urlEncode($input.body)&MessageGroupId=$util.urlEncode($input.path('$.merchant_id'))&MessageDeduplicationId=$util.urlEncode($input.path('$.order_id'))

aws: [ERROR]: An error occurred (ParamValidation): Error parsing parameter '--patch-operations': Expected: ',', received: ''' for input:
 op=replace,path=/requestTemplates/application~1json,value=Action=SendMessage&MessageBody=$util.urlEncode($input.body)&MessageGroupId=$util.urlEncode($input.path('$.merchant_id'))&MessageDeduplicationId=$util.urlEncode($input.path('$.order_id'))
                                                                                                                                                                 ^
=== verify integration ===
{
    "application/json": "Action=SendMessage&MessageBody=$util.urlEncode($input.body)&MessageGroupId=$util.urlEncode($input.path('$.order_id'))&MessageDeduplicationId=$util.urlEncode($input.path('$.order_id'))"
}
=== redeploy stage dev ===
redeployed

Patch integration template via cli-input-json

shell
set -e
API_ID=$(cat /tmp/api_id)
ORDERS_ID=$(cat /tmp/orders_id)

TEMPLATE="Action=SendMessage&MessageBody=\$util.urlEncode(\$input.body)&MessageGroupId=\$util.urlEncode(\$input.path('\$.merchant_id'))&MessageDeduplicationId=\$util.urlEncode(\$input.path('\$.order_id'))"

# Build a JSON file with the patch ops, avoiding shell-quote pitfalls
PATCH_JSON=$(jq -nc \
  --arg api "$API_ID" \
  --arg res "$ORDERS_ID" \
  --arg t "$TEMPLATE" \
  '{restApiId:$api,resourceId:$res,httpMethod:"POST",patchOperations:[{op:"replace",path:"/requestTemplates/application~1json",value:$t}]}')
echo "$PATCH_JSON" > /tmp/patch.json

aws apigateway update-integration --cli-input-json "$(cat /tmp/patch.json)" \
  --query 'requestTemplates' >/dev/null

echo "=== verify ==="
aws apigateway get-integration \
  --rest-api-id "$API_ID" --resource-id "$ORDERS_ID" --http-method POST \
  --query 'requestTemplates'

echo "=== redeploy ==="
aws apigateway create-deployment --rest-api-id "$API_ID" --stage-name dev --query 'id' --output text
output
=== verify ===
{
    "application/json": "Action=SendMessage&MessageBody=$util.urlEncode($input.body)&MessageGroupId=$util.urlEncode($input.path('$.merchant_id'))&MessageDeduplicationId=$util.urlEncode($input.path('$.order_id'))"
}
=== redeploy ===
htxbp9hven

[stdout]
=== verify ===
{
    "application/json": "Action=SendMessage&MessageBody=$util.urlEncode($input.body)&MessageGroupId=$util.urlEncode($input.path('$.merchant_id'))&MessageDeduplicationId=$util.urlEncode($input.path('$.order_id'))"
}
=== redeploy ===
htxbp9hven
Template updated and stage redeployed. Now re-verify with merchant-grouped messages.

Re-verify after group-id change

shell
set -e
API_ID=$(cat /tmp/api_id)
URL="http://localstack:4566/restapis/${API_ID}/dev/_user_request_/orders"
DLQ_URL=$(cat /tmp/dlq_url)
MAIN_URL=$(cat /tmp/main_url)

echo "=== clear table ==="
for oid in o-1 o-2 o-3; do
  aws dynamodb delete-item --table-name orders --key "{\"order_id\":{\"S\":\"$oid\"}}" >/dev/null
done

echo "=== POST: idempotency on m-A/o-A1 ==="
curl -sS -o /dev/null -w "1st HTTP %{http_code}\n" -X POST "$URL" \
  -H 'Content-Type: application/json' \
  -d '{"order_id":"o-A1","merchant_id":"m-A","amount":100}'
sleep 4
ORIG=$(aws dynamodb get-item --table-name orders --key '{"order_id":{"S":"o-A1"}}' --query 'Item.created_at.N' --output text)
echo "after 1st POST created_at=$ORIG"
sleep 2
curl -sS -o /dev/null -w "2nd HTTP %{http_code}\n" -X POST "$URL" \
  -H 'Content-Type: application/json' \
  -d '{"order_id":"o-A1","merchant_id":"m-A","amount":100}'
sleep 4
NEW=$(aws dynamodb get-item --table-name orders --key '{"order_id":{"S":"o-A1"}}' --query 'Item.created_at.N' --output text)
echo "after 2nd POST created_at=$NEW"
[ "$ORIG" = "$NEW" ] && echo "IDEMPOTENT OK" || echo "FAIL: row changed"

echo
echo "=== ordering: two orders under same merchant ==="
curl -sS -o /dev/null -w "1st HTTP %{http_code}\n" -X POST "$URL" \
  -H 'Content-Type: application/json' \
  -d '{"order_id":"o-A2","merchant_id":"m-A","amount":50}'
sleep 1
curl -sS -o /dev/null -w "2nd HTTP %{http_code}\n" -X POST "$URL" \
  -H 'Content-Type: application/json' \
  -d '{"order_id":"o-A3","merchant_id":"m-A","amount":75}'
sleep 8

echo "=== final table ==="
aws dynamodb scan --table-name orders \
  --query 'Items[*].{order_id:order_id.S,merchant_id:merchant_id.S,amount:amount.N,created_at:created_at.N}'

T2=$(aws dynamodb get-item --table-name orders --key '{"order_id":{"S":"o-A2"}}' --query 'Item.created_at.N' --output text)
T3=$(aws dynamodb get-item --table-name orders --key '{"order_id":{"S":"o-A3"}}' --query 'Item.created_at.N' --output text)
echo "o-A2 ts=$T2  o-A3 ts=$T3"
[ "$T2" -le "$T3" ] && echo "ORDERING OK (o-A2 ts <= o-A3 ts)" || echo "FAIL: ordering"

echo "=== queue depths ==="
aws sqs get-queue-attributes --queue-url "$MAIN_URL" --attribute-names ApproximateNumberOfMessages --query 'Attributes'
aws sqs get-queue-attributes --queue-url "$DLQ_URL" --attribute-names ApproximateNumberOfMessages --query 'Attributes'
output
=== clear table ===
=== POST: idempotency on m-A/o-A1 ===
1st HTTP 200
after 1st POST created_at=None
2nd HTTP 200
after 2nd POST created_at=1777383984
FAIL: row changed

=== ordering: two orders under same merchant ===
1st HTTP 200
2nd HTTP 200
=== final table ===
[
    {
        "order_id": "o-A3",
        "merchant_id": "m-A",
        "amount": "75",
        "created_at": "1777383992"
    },
    {
        "order_id": "o-A2",
        "merchant_id": "m-A",
        "amount": "50",
        "created_at": "1777383989"
    },
    {
        "order_id": "o-A1",
        "merchant_id": "m-A",
        "amount": "100",
        "created_at": "1777383984"
    }
]
o-A2 ts=1777383989  o-A3 ts=1777383992
ORDERING OK (o-A2 ts <= o-A3 ts)
=== queue depths ===
{
    "ApproximateNumberOfMessages": "0"
}
{
    "ApproximateNumberOfMessages": "0"
}

[stdout]
=== clear table ===
=== POST: idempotency on m-A/o-A1 ===
1st HTTP 200
after 1st POST created_at=None
2nd HTTP 200
after 2nd POST created_at=1777383984
FAIL: row changed

=== ordering: two orders under same merchant ===
1st HTTP 200
2nd HTTP 200
=== final table ===
[
    {
        "order_id": "o-A3",
        "merchant_id": "m-A",
        "amount": "75",
        "created_at": "1777383992"
    },
    {
        "order_id": "o-A2",
        "merchant_id": "m-A",
        "amount": "50",
        "created_at": "1777383989"
    },
    {
        "order_id": "o-A1",
        "merchant_id": "m-A",
        "amount": "100",
        "created_at": "1777383984"
    }
]
o-A2 ts=1777383989  o-A3 ts=1777383992
ORDERING OK (o-A2 ts <= o-A3 ts)
=== queue depths ===
{
    "ApproximateNumberOfMessages": "0"
}
{
    "ApproximateNumberOfMessages": "0"
}
That "FAIL" was a polling timing artifact , the first POST's row hadn't been written yet at 4s, then the second POST's message was deduped by SQS so no second write happened. Final state: one row per order, ordering preserved. Let me redo idempotency with longer waits to make it unambiguous.

Final clean verification with longer waits

shell
set -e
API_ID=$(cat /tmp/api_id)
URL="http://localstack:4566/restapis/${API_ID}/dev/_user_request_/orders"
DLQ_URL=$(cat /tmp/dlq_url)
MAIN_URL=$(cat /tmp/main_url)

# clear
for oid in o-A1 o-A2 o-A3; do
  aws dynamodb delete-item --table-name orders --key "{\"order_id\":{\"S\":\"$oid\"}}" >/dev/null
done

echo "=== 1st POST o-A1 ==="
curl -sS -o /dev/null -w "HTTP %{http_code}\n" -X POST "$URL" \
  -H 'Content-Type: application/json' \
  -d '{"order_id":"o-A1","merchant_id":"m-A","amount":100}'
echo "wait 12s for write..."
sleep 12
ORIG=$(aws dynamodb get-item --table-name orders --key '{"order_id":{"S":"o-A1"}}' --query 'Item.created_at.N' --output text)
echo "after 1st POST o-A1 created_at=$ORIG"
[ "$ORIG" = "None" ] && { echo "FATAL: row missing"; exit 1; }

echo
echo "=== 2nd POST o-A1 (duplicate) ==="
sleep 3
curl -sS -o /dev/null -w "HTTP %{http_code}\n" -X POST "$URL" \
  -H 'Content-Type: application/json' \
  -d '{"order_id":"o-A1","merchant_id":"m-A","amount":100}'
sleep 12
NEW=$(aws dynamodb get-item --table-name orders --key '{"order_id":{"S":"o-A1"}}' --query 'Item.created_at.N' --output text)
COUNT=$(aws dynamodb scan --table-name orders --select COUNT --query 'Count')
echo "after dup POST: created_at=$NEW   row_count=$COUNT"
[ "$ORIG" = "$NEW" ] && [ "$COUNT" = "1" ] && echo "IDEMPOTENT OK" || echo "IDEMPOTENT FAIL"

echo
echo "=== ordering test ==="
curl -sS -o /dev/null -w "o-A2 HTTP %{http_code}\n" -X POST "$URL" \
  -H 'Content-Type: application/json' \
  -d '{"order_id":"o-A2","merchant_id":"m-A","amount":50}'
sleep 1
curl -sS -o /dev/null -w "o-A3 HTTP %{http_code}\n" -X POST "$URL" \
  -H 'Content-Type: application/json' \
  -d '{"order_id":"o-A3","merchant_id":"m-A","amount":75}'
sleep 12

T2=$(aws dynamodb get-item --table-name orders --key '{"order_id":{"S":"o-A2"}}' --query 'Item.created_at.N' --output text)
T3=$(aws dynamodb get-item --table-name orders --key '{"order_id":{"S":"o-A3"}}' --query 'Item.created_at.N' --output text)
echo "o-A2 ts=$T2  o-A3 ts=$T3"
[ "$T2" -le "$T3" ] && echo "ORDER OK" || echo "ORDER FAIL"

echo
echo "=== final state ==="
aws dynamodb scan --table-name orders --query 'Items[*].{order_id:order_id.S,merchant_id:merchant_id.S,amount:amount.N,created_at:created_at.N}'
echo "main:"
aws sqs get-queue-attributes --queue-url "$MAIN_URL" --attribute-names ApproximateNumberOfMessages ApproximateNumberOfMessagesNotVisible --query 'Attributes'
echo "dlq:"
aws sqs get-queue-attributes --queue-url "$DLQ_URL" --attribute-names ApproximateNumberOfMessages --query 'Attributes'
output
Exit code 1
=== 1st POST o-A1 ===
HTTP 200
wait 12s for write...
after 1st POST o-A1 created_at=None
FATAL: row missing

[error] tool reported failure
Right , within the 5-minute SQS FIFO dedup window, my earlier `o-A1` POSTs are still suppressing new ones with the same `MessageDeduplicationId`. The spec calls duplicate POSTs a no-op at storage, which is satisfied by either SQS dedup or the conditional put. Let me re-verify with fresh order IDs.

Final verification with fresh order IDs

shell
set -e
API_ID=$(cat /tmp/api_id)
URL="http://localstack:4566/restapis/${API_ID}/dev/_user_request_/orders"
DLQ_URL=$(cat /tmp/dlq_url)
MAIN_URL=$(cat /tmp/main_url)

# wipe table
ORDER_IDS=$(aws dynamodb scan --table-name orders --query 'Items[*].order_id.S' --output text)
for oid in $ORDER_IDS; do
  aws dynamodb delete-item --table-name orders --key "{\"order_id\":{\"S\":\"$oid\"}}" >/dev/null
done

# fresh order IDs to avoid SQS-dedup-window collisions
ID1="ord-$RANDOM-$RANDOM"
ID2="ord-$RANDOM-$RANDOM"
ID3="ord-$RANDOM-$RANDOM"
echo "ID1=$ID1 ID2=$ID2 ID3=$ID3"

echo "=== 1st POST $ID1 ==="
curl -sS -o /dev/null -w "HTTP %{http_code}\n" -X POST "$URL" \
  -H 'Content-Type: application/json' \
  -d "{\"order_id\":\"$ID1\",\"merchant_id\":\"m-X\",\"amount\":100}"
sleep 8
ORIG=$(aws dynamodb get-item --table-name orders --key "{\"order_id\":{\"S\":\"$ID1\"}}" --query 'Item.created_at.N' --output text)
echo "1st row created_at=$ORIG"
[ "$ORIG" = "None" ] && { echo "FATAL: missing"; exit 1; }

echo
echo "=== 2nd POST same body (idempotency) ==="
sleep 3
curl -sS -o /dev/null -w "HTTP %{http_code}\n" -X POST "$URL" \
  -H 'Content-Type: application/json' \
  -d "{\"order_id\":\"$ID1\",\"merchant_id\":\"m-X\",\"amount\":100}"
sleep 8
NEW=$(aws dynamodb get-item --table-name orders --key "{\"order_id\":{\"S\":\"$ID1\"}}" --query 'Item.created_at.N' --output text)
COUNT=$(aws dynamodb scan --table-name orders --select COUNT --query 'Count')
echo "after dup: created_at=$NEW count=$COUNT"
[ "$ORIG" = "$NEW" ] && [ "$COUNT" = "1" ] && echo "IDEMPOTENT OK" || { echo "IDEMPOTENT FAIL"; exit 1; }

echo
echo "=== ordering test ==="
curl -sS -o /dev/null -w "$ID2 HTTP %{http_code}\n" -X POST "$URL" \
  -H 'Content-Type: application/json' \
  -d "{\"order_id\":\"$ID2\",\"merchant_id\":\"m-X\",\"amount\":50}"
sleep 1
curl -sS -o /dev/null -w "$ID3 HTTP %{http_code}\n" -X POST "$URL" \
  -H 'Content-Type: application/json' \
  -d "{\"order_id\":\"$ID3\",\"merchant_id\":\"m-X\",\"amount\":75}"
sleep 10

T2=$(aws dynamodb get-item --table-name orders --key "{\"order_id\":{\"S\":\"$ID2\"}}" --query 'Item.created_at.N' --output text)
T3=$(aws dynamodb get-item --table-name orders --key "{\"order_id\":{\"S\":\"$ID3\"}}" --query 'Item.created_at.N' --output text)
echo "ID2 ts=$T2  ID3 ts=$T3"
[ "$T2" -le "$T3" ] && echo "ORDER OK" || { echo "ORDER FAIL"; exit 1; }

echo
echo "=== final ==="
aws dynamodb scan --table-name orders --query 'Items[*].{order_id:order_id.S,merchant_id:merchant_id.S,amount:amount.N,created_at:created_at.N}'
echo "main:"; aws sqs get-queue-attributes --queue-url "$MAIN_URL" --attribute-names ApproximateNumberOfMessages ApproximateNumberOfMessagesNotVisible --query 'Attributes'
echo "dlq:"; aws sqs get-queue-attributes --queue-url "$DLQ_URL" --attribute-names ApproximateNumberOfMessages --query 'Attributes'
output
Exit code 1
ID1=ord-6176-12246 ID2=ord-15022-5410 ID3=ord-15017-20842
=== 1st POST ord-6176-12246 ===
HTTP 200
1st row created_at=None
FATAL: missing

[error] tool reported failure
Something regressed after the redeploy , fresh ID still not landing. Let me trace.

Inspect queue and lambda logs

shell
set -e
MAIN_URL=$(cat /tmp/main_url)
echo "=== queue depth ==="
aws sqs get-queue-attributes --queue-url "$MAIN_URL" --attribute-names ApproximateNumberOfMessages ApproximateNumberOfMessagesNotVisible
echo "=== peek a message ==="
aws sqs receive-message --queue-url "$MAIN_URL" --max-number-of-messages 1 --visibility-timeout 1 --wait-time-seconds 1 --attribute-names All --message-attribute-names All 2>&1 | head -50

echo "=== recent lambda log streams ==="
aws logs describe-log-streams \
  --log-group-name "/aws/lambda/orders-consumer" \
  --order-by LastEventTime --descending --max-items 3 \
  --query 'logStreams[*].logStreamName' --output text
output
=== queue depth ===
{
    "Attributes": {
        "ApproximateNumberOfMessages": "0",
        "ApproximateNumberOfMessagesNotVisible": "0"
    }
}
=== peek a message ===
=== recent lambda log streams ===
2026/04/28/[$LATEST]78c825fc31d64f1c5a2aad84944c5f42	2026/04/28/[$LATEST]6547c8f5411c5213a6ee8524e4d54e86	2026/04/28/[$LATEST]3daa518a02ed6bf053946e0694f07d7f
None

[stdout]
=== queue depth ===
{
    "Attributes": {
        "ApproximateNumberOfMessages": "0",
        "ApproximateNumberOfMessagesNotVisible": "0"
    }
}
=== peek a message ===
=== recent lambda log streams ===
2026/04/28/[$LATEST]78c825fc31d64f1c5a2aad84944c5f42	2026/04/28/[$LATEST]6547c8f5411c5213a6ee8524e4d54e86	2026/04/28/[$LATEST]3daa518a02ed6bf053946e0694f07d7f
None

Read latest lambda logs

shell
set -e
LOG_GROUP="/aws/lambda/orders-consumer"
# Get most recent stream
STREAM=$(aws logs describe-log-streams \
  --log-group-name "$LOG_GROUP" \
  --order-by LastEventTime --descending --max-items 1 \
  --query 'logStreams[0].logStreamName' --output text)
echo "STREAM=$STREAM"
aws logs get-log-events --log-group-name "$LOG_GROUP" --log-stream-name "$STREAM" \
  --limit 200 --query 'events[*].message' --output text
output
Exit code 254
STREAM=2026/04/28/[$LATEST]78c825fc31d64f1c5a2aad84944c5f42
None

aws: [ERROR]: An error occurred (ResourceNotFoundException) when calling the GetLogEvents operation: The specified log stream does not exist.

[error] tool reported failure

Get logs with literal $LATEST

shell
set -e
LOG_GROUP="/aws/lambda/orders-consumer"
STREAM='2026/04/28/[$LATEST]78c825fc31d64f1c5a2aad84944c5f42'
aws logs get-log-events --log-group-name "$LOG_GROUP" --log-stream-name "$STREAM" \
  --limit 200 --query 'events[*].message' --output text 2>&1 | head -50
output
START RequestId: 0fc7bf2c-80e2-4965-9919-3fcfab03a79a Version: $LATEST
	END RequestId: 0fc7bf2c-80e2-4965-9919-3fcfab03a79a
	REPORT RequestId: 0fc7bf2c-80e2-4965-9919-3fcfab03a79a	Duration: 55.35 ms	Billed Duration: 56 ms	Memory Size: 512 MB	Max Memory Used: 512 MB

[stdout]
START RequestId: 0fc7bf2c-80e2-4965-9919-3fcfab03a79a Version: $LATEST
	END RequestId: 0fc7bf2c-80e2-4965-9919-3fcfab03a79a
	REPORT RequestId: 0fc7bf2c-80e2-4965-9919-3fcfab03a79a	Duration: 55.35 ms	Billed Duration: 56 ms	Memory Size: 512 MB	Max Memory Used: 512 MB

Direct check for the missing row

shell
set -e
LOG_GROUP="/aws/lambda/orders-consumer"
echo "=== checking specific row ==="
aws dynamodb get-item --table-name orders --key '{"order_id":{"S":"ord-6176-12246"}}'
echo "=== full table scan ==="
aws dynamodb scan --table-name orders
output
=== checking specific row ===
{
    "Item": {
        "created_at": {
            "N": "1777384083"
        },
        "amount": {
            "N": "100"
        },
        "merchant_id": {
            "S": "m-X"
        },
        "order_id": {
            "S": "ord-6176-12246"
        }
    }
}
=== full table scan ===
{
    "Items": [
        {
            "created_at": {
                "N": "1777384083"
            },
            "amount": {
                "N": "100"
            },
            "merchant_id": {
                "S": "m-X"
            },
            "order_id": {
                "S": "ord-6176-12246"
            }
        }
    ],
    "Count": 1,
    "ScannedCount": 1,
    "ConsumedCapacity": null
}

[stdout]
=== checking specific row ===
{
    "Item": {
        "created_at": {
            "N": "1777384083"
        },
        "amount": {
            "N": "100"
        },
        "merchant_id": {
            "S": "m-X"
        },
        "order_id": {
            "S": "ord-6176-12246"
        }
    }
}
=== full table scan ===
{
    "Items": [
        {
            "created_at": {
                "N": "1777384083"
            },
            "amount": {
                "N": "100"
            },
            "merchant_id": {
                "S": "m-X"
            },
            "order_id": {
                "S": "ord-6176-12246"
            }
        }
    ],
    "Count": 1,
    "ScannedCount": 1,
    "ConsumedCapacity": null
}
The row IS there , my 8-second wait raced with eventual consistency. Re-run the full verification with larger waits.

Generous-wait verification

shell
set -e
API_ID=$(cat /tmp/api_id)
URL="http://localstack:4566/restapis/${API_ID}/dev/_user_request_/orders"
DLQ_URL=$(cat /tmp/dlq_url)
MAIN_URL=$(cat /tmp/main_url)

# wipe table
ORDER_IDS=$(aws dynamodb scan --table-name orders --query 'Items[*].order_id.S' --output text)
for oid in $ORDER_IDS; do
  aws dynamodb delete-item --table-name orders --key "{\"order_id\":{\"S\":\"$oid\"}}" >/dev/null
done

ID1="ord-$RANDOM-$RANDOM-$$"
ID2="ord-$RANDOM-$RANDOM-$$"
ID3="ord-$RANDOM-$RANDOM-$$"
echo "ID1=$ID1 ID2=$ID2 ID3=$ID3"

wait_for_row() {
  local oid="$1"
  for i in $(seq 1 20); do
    R=$(aws dynamodb get-item --table-name orders --key "{\"order_id\":{\"S\":\"$oid\"}}" --query 'Item.created_at.N' --output text)
    [ "$R" != "None" ] && [ -n "$R" ] && { echo "$R"; return 0; }
    sleep 1
  done
  echo "TIMEOUT" >&2
  return 1
}

echo "=== POST $ID1 ==="
curl -sS -o /dev/null -w "HTTP %{http_code}\n" -X POST "$URL" \
  -H 'Content-Type: application/json' -d "{\"order_id\":\"$ID1\",\"merchant_id\":\"m-Z\",\"amount\":100}"
ORIG=$(wait_for_row "$ID1")
echo "1st row created_at=$ORIG"

echo "=== duplicate POST ==="
sleep 2
curl -sS -o /dev/null -w "HTTP %{http_code}\n" -X POST "$URL" \
  -H 'Content-Type: application/json' -d "{\"order_id\":\"$ID1\",\"merchant_id\":\"m-Z\",\"amount\":100}"
sleep 10
NEW=$(aws dynamodb get-item --table-name orders --key "{\"order_id\":{\"S\":\"$ID1\"}}" --query 'Item.created_at.N' --output text)
COUNT=$(aws dynamodb scan --table-name orders --select COUNT --query 'Count')
echo "after dup: created_at=$NEW count=$COUNT"
[ "$ORIG" = "$NEW" ] && [ "$COUNT" = "1" ] && echo "IDEMPOTENT OK" || echo "IDEMPOTENT FAIL"

echo "=== ordering: POST $ID2 then $ID3 (same merchant) ==="
curl -sS -o /dev/null -w "$ID2 HTTP %{http_code}\n" -X POST "$URL" \
  -H 'Content-Type: application/json' -d "{\"order_id\":\"$ID2\",\"merchant_id\":\"m-Z\",\"amount\":50}"
sleep 1
curl -sS -o /dev/null -w "$ID3 HTTP %{http_code}\n" -X POST "$URL" \
  -H 'Content-Type: application/json' -d "{\"order_id\":\"$ID3\",\"merchant_id\":\"m-Z\",\"amount\":75}"
T2=$(wait_for_row "$ID2")
T3=$(wait_for_row "$ID3")
echo "$ID2 ts=$T2  $ID3 ts=$T3"
[ "$T2" -le "$T3" ] && echo "ORDER OK" || echo "ORDER FAIL"

echo
echo "=== final ==="
aws dynamodb scan --table-name orders --query 'Items[*].{order_id:order_id.S,merchant_id:merchant_id.S,amount:amount.N,created_at:created_at.N}'
echo "main:"; aws sqs get-queue-attributes --queue-url "$MAIN_URL" --attribute-names ApproximateNumberOfMessages ApproximateNumberOfMessagesNotVisible --query 'Attributes'
echo "dlq:"; aws sqs get-queue-attributes --queue-url "$DLQ_URL" --attribute-names ApproximateNumberOfMessages --query 'Attributes'
output
ID1=ord-27582-30878-1756 ID2=ord-29724-8220-1756 ID3=ord-23738-25359-1756
=== POST ord-27582-30878-1756 ===
HTTP 200
1st row created_at=1777384127
=== duplicate POST ===
HTTP 200
after dup: created_at=1777384127 count=1
IDEMPOTENT OK
=== ordering: POST ord-29724-8220-1756 then ord-23738-25359-1756 (same merchant) ===
ord-29724-8220-1756 HTTP 200
ord-23738-25359-1756 HTTP 200
ord-29724-8220-1756 ts=1777384148  ord-23738-25359-1756 ts=1777384148
ORDER OK

=== final ===
[
    {
        "order_id": "ord-27582-30878-1756",
        "merchant_id": "m-Z",
        "amount": "100",
        "created_at": "1777384127"
    },
    {
        "order_id": "ord-29724-8220-1756",
        "merchant_id": "m-Z",
        "amount": "50",
        "created_at": "1777384148"
    },
    {
        "order_id": "ord-23738-25359-1756",
        "merchant_id": "m-Z",
        "amount": "75",
        "created_at": "1777384148"
    }
]
main:
{
    "ApproximateNumberOfMessages": "0",
    "ApproximateNumberOfMessagesNotVisible": "0"
}
dlq:
{
    "ApproximateNumberOfMessages": "0"
}

[stdout]
ID1=ord-27582-30878-1756 ID2=ord-29724-8220-1756 ID3=ord-23738-25359-1756
=== POST ord-27582-30878-1756 ===
HTTP 200
1st row created_at=1777384127
=== duplicate POST ===
HTTP 200
after dup: created_at=1777384127 count=1
IDEMPOTENT OK
=== ordering: POST ord-29724-8220-1756 then ord-23738-25359-1756 (same merchant) ===
ord-29724-8220-1756 HTTP 200
ord-23738-25359-1756 HTTP 200
ord-29724-8220-1756 ts=1777384148  ord-23738-25359-1756 ts=1777384148
ORDER OK

=== final ===
[
    {
        "order_id": "ord-27582-30878-1756",
        "merchant_id": "m-Z",
        "amount": "100",
        "created_at": "1777384127"
    },
    {
        "order_id": "ord-29724-8220-1756",
        "merchant_id": "m-Z",
        "amount": "50",
        "created_at": "1777384148"
    },
    {
        "order_id": "ord-23738-25359-1756",
        "merchant_id": "m-Z",
        "amount": "75",
        "created_at": "1777384148"
    }
]
main:
{
    "ApproximateNumberOfMessages": "0",
    "ApproximateNumberOfMessagesNotVisible": "0"
}
dlq:
{
    "ApproximateNumberOfMessages": "0"
}
All requirements verified end-to-end: - **HTTP 200** on every POST - **Idempotent**: duplicate POST returned 200, row count stayed at 1, `created_at` unchanged - **Ordering preserved** under same merchant (T₂ ≤ T₃) - **Main queue empty, DLQ empty**

Final sanity check on stage/resources

shell
set -e
API_ID=$(cat /tmp/api_id)
echo "=== final stage state ==="
aws apigateway get-stage --rest-api-id "$API_ID" --stage-name dev \
  --query '{stage:stageName,deploymentId:deploymentId}'
echo "=== resources ==="
aws apigateway get-resources --rest-api-id "$API_ID" \
  --query 'items[*].{path:path,methods:resourceMethods}'
output
=== final stage state ===
{
    "stage": "dev",
    "deploymentId": "htxbp9hven"
}
=== resources ===
[
    {
        "path": "/",
        "methods": null
    },
    {
        "path": "/orders",
        "methods": {
            "POST": {
                "httpMethod": "POST",
                "authorizationType": "NONE",
                "apiKeyRequired": false,
                "methodResponses": {
                    "200": {
                        "statusCode": "200",
                        "responseModels": {
                            "application/json": "Empty"
                        }
                    }
                },
                "methodIntegration": {
                    "type": "AWS",
                    "httpMethod": "POST",
                    "uri": "arn:aws:apigateway:us-east-1:sqs:path/000000000000/orders.fifo",
                    "credentials": "arn:aws:iam::000000000000:role/apigw-to-sqs-role",
                    "requestParameters": {
                        "integration.request.header.Content-Type": "'application/x-www-form-urlencoded'"
                    },
                    "requestTemplates": {
                        "application/json": "Action=SendMessage&MessageBody=$util.urlEncode($input.body)&MessageGroupId=$util.urlEncode($input.path('$.merchant_id'))&MessageDeduplicationId=$util.urlEncode($input.path('$.order_id'))"
                    },
                    "passthroughBehavior": "NEVER",
                    "timeoutInMillis": 29000,
                    "cacheNamespace": "itn2hsou8j",
                    "cacheKeyParameters": [],
                    "integrationResponses": {
                        "200": {
                            "statusCode": "200",
                            "responseTemplates": {
                                "application/json": "{\"ok\":true}"
                            }
                        }
                    }
                }
            }
        }
    }
]

[stdout]
=== final stage state ===
{
    "stage": "dev",
    "deploymentId": "htxbp9hven"
}
=== resources ===
[
    {
        "path": "/",
        "methods": null
    },
    {
        "path": "/orders",
        "methods": {
            "POST": {
                "httpMethod": "POST",
                "authorizationType": "NONE",
                "apiKeyRequired": false,
                "methodResponses": {
                    "200": {
                        "statusCode": "200",
                        "responseModels": {
                            "application/json": "Empty"
                        }
                    }
                },
                "methodIntegration": {
                    "type": "AWS",
                    "httpMethod": "POST",
                    "uri": "arn:aws:apigateway:us-east-1:sqs:path/000000000000/orders.fifo",
                    "credentials": "arn:aws:iam::000000000000:role/apigw-to-sqs-role",
                    "requestParameters": {
                        "integration.request.header.Content-Type": "'application/x-www-form-urlencoded'"
                    },
                    "requestTemplates": {
                        "application/json": "Action=SendMessage&MessageBody=$util.urlEncode($input.body)&MessageGroupId=$util.urlEncode($input.path('$.merchant_id'))&MessageDeduplicationId=$util.urlEncode($input.path('$.order_id'))"
                    },
                    "passthroughBehavior": "NEVER",
                    "timeoutInMillis": 29000,
                    "cacheNamespace": "itn2hsou8j",
                    "cacheKeyParameters": [],
                    "integrationResponses": {
                        "200": {
                            "statusCode": "200",
                            "responseTemplates": {
                                "application/json": "{\"ok\":true}"
                            }
                        }
                    }
                }
            }
        }
    }
]
  • Create DDB table
  • Create FIFO queues with redrive
  • Fix consumer Lambda role permissions
  • Replace Lambda handler
  • Create event source mapping
  • Create REST API + resource + method + integration
  • Create apigw→sqs role and policy
  • Deploy stage dev
  • End-to-end verify
Pipeline is complete and verified. Summary of what was built: **Storage** , DDB table `orders` (pk `order_id` String, on-demand billing). **Queues** , `orders.fifo` (FIFO, content-based dedup off) with redrive to `orders-dlq.fifo` at maxReceiveCount=3. **Consumer Lambda** (`orders-consumer`) - Replaced handler: idempotent via `ConditionExpression: attribute_not_exists(order_id)` (suppresses `ConditionalCheckFailedException`); returns the AWS-required `{"batchItemFailures":[…]}` shape. - Role `orders-consumer-role` got an inline policy adding `dynamodb:PutItem/GetItem/UpdateItem/DescribeTable` on the orders table and `sqs:ReceiveMessage/DeleteMessage/GetQueueAttributes/ChangeMessageVisibility` on the main queue (basic-execution managed policy was already attached). - Event source mapping main queue → lambda with `FunctionResponseTypes=[ReportBatchItemFailures]`. **API Gateway** , `orders-api` with `/orders` POST. Integration is `type=AWS` (direct SQS, not AWS_PROXY), `credentials=apigw-to-sqs-role`, `Content-Type: application/x-www-form-urlencoded`, mapping template: ``` Action=SendMessage&MessageBody=$util.urlEncode($input.body) &MessageGroupId=$util.urlEncode($input.path('$.merchant_id')) &MessageDeduplicationId=$util.urlEncode($input.path('$.order_id')) ``` `MessageGroupId=merchant_id` preserves cross-order ordering within a merchant; `MessageDeduplicationId=order_id` gives SQS-level dedup as well as DDB-level. Method response 200 with `Empty` model, integration response 200 returning `{"ok":true}`. **`apigw-to-sqs-role`** , assumed by `apigateway.amazonaws.com`; inline policy with `sqs:SendMessage/GetQueueUrl/GetQueueAttributes` on the main queue plus CloudWatch Logs. **Stage `dev`** , created via `apigateway create-deployment` after each wiring change (twice total: initial deploy and after the GroupId fix). Verified: HTTP 200 every POST · single row per order_id · duplicate POST → unchanged row · cross-order timestamps preserve posted order under same merchant · DLQ empty.
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/DTz9QPZFYCwaFtkTKT1hg/bin/python
cachedir: .pytest_cache
rootdir: /tests
plugins: json-ctrf-0.3.5
collecting ... collected 19 items

../tests/test_outputs.py::test_localstack_reachable PASSED               [  5%]
../tests/test_outputs.py::test_main_fifo_queue_exists PASSED             [ 10%]
../tests/test_outputs.py::test_dlq_fifo_queue_exists PASSED              [ 15%]
../tests/test_outputs.py::test_ddb_table_exists PASSED                   [ 21%]
../tests/test_outputs.py::test_lambda_and_esm_exist PASSED               [ 26%]
../tests/test_outputs.py::test_rest_api_exists_with_post_orders PASSED   [ 31%]
../tests/test_outputs.py::test_integration_uri_targets_fifo_queue PASSED [ 36%]
../tests/test_outputs.py::test_integration_credentials_role_is_set PASSED [ 42%]
../tests/test_outputs.py::test_integration_sets_content_type_header PASSED [ 47%]
../tests/test_outputs.py::test_integration_request_template_uses_full_body PASSED [ 52%]
../tests/test_outputs.py::test_integration_request_template_has_message_group_id PASSED [ 57%]
../tests/test_outputs.py::test_integration_request_template_has_dedup_id PASSED [ 63%]
../tests/test_outputs.py::test_integration_template_identifiers_are_request_derived PASSED [ 68%]
../tests/test_outputs.py::test_stage_deployment_id_was_refreshed PASSED  [ 73%]
../tests/test_outputs.py::test_event_source_mapping_declares_report_batch_item_failures PASSED [ 78%]
../tests/test_outputs.py::test_lambda_handler_idempotency_and_response_shape PASSED [ 84%]
../tests/test_outputs.py::test_end_to_end_post_reaches_ddb_no_dlq PASSED [ 89%]
../tests/test_outputs.py::test_end_to_end_fifo_group_ordering PASSED     [ 94%]
../tests/test_outputs.py::test_end_to_end_duplicate_post_is_idempotent PASSED [100%]

=============================== warnings summary ===============================
test_outputs.py: 66 warnings
  /root/.cache/uv/archive-v0/DTz9QPZFYCwaFtkTKT1hg/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_localstack_reachable
PASSED ../tests/test_outputs.py::test_main_fifo_queue_exists
PASSED ../tests/test_outputs.py::test_dlq_fifo_queue_exists
PASSED ../tests/test_outputs.py::test_ddb_table_exists
PASSED ../tests/test_outputs.py::test_lambda_and_esm_exist
PASSED ../tests/test_outputs.py::test_rest_api_exists_with_post_orders
PASSED ../tests/test_outputs.py::test_integration_uri_targets_fifo_queue
PASSED ../tests/test_outputs.py::test_integration_credentials_role_is_set
PASSED ../tests/test_outputs.py::test_integration_sets_content_type_header
PASSED ../tests/test_outputs.py::test_integration_request_template_uses_full_body
PASSED ../tests/test_outputs.py::test_integration_request_template_has_message_group_id
PASSED ../tests/test_outputs.py::test_integration_request_template_has_dedup_id
PASSED ../tests/test_outputs.py::test_integration_template_identifiers_are_request_derived
PASSED ../tests/test_outputs.py::test_stage_deployment_id_was_refreshed
PASSED ../tests/test_outputs.py::test_event_source_mapping_declares_report_batch_item_failures
PASSED ../tests/test_outputs.py::test_lambda_handler_idempotency_and_response_shape
PASSED ../tests/test_outputs.py::test_end_to_end_post_reaches_ddb_no_dlq
PASSED ../tests/test_outputs.py::test_end_to_end_fifo_group_ordering
PASSED ../tests/test_outputs.py::test_end_to_end_duplicate_post_is_idempotent
======================= 19 passed, 66 warnings in 26.36s =======================

Reproduce this trial: git checkout 2f94510 && PYTHONPATH=src python3 scripts/build_site.py , then open trial/trial_be33eb183e4b41c3. Re-running the agent live requires EVAL_PLATFORM_ENABLE_OAUTH_SMOKE=1 and is non-deterministic.

Trial trial_be33eb183e4b41c3 · verifier authoritative; classifier explanatory.