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AWS Lambda Durable Functions

AWSOfficialPublished by AWS

  • Skill
  • Tool integration
  • Cloud and DevOps
  • Apache-2.0
  • Low risk
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From the author

Builds resilient, long-running, multi-step applications with AWS Lambda durable functions with automatic state persistence, retry logic, and orchestration for long-running executions. Covers the critical replay model, step operations, wait/callback patterns, error handling with saga pattern, testing with LocalDurableTestRunner. Triggers on phrases like lambda durable functions, durable execution, workflow orchestration, state machines, retry/checkpoint patterns, long-running stateful Lambda functions, saga pattern, human-in-the-loop callbacks, reliable serverless applications, context.step, context.wait, context.invoke, context.runInChildContext, withDurableExecution, DurableContext, UnrecoverableInvocationError, durable-execution-sdk, qualified ARN invocation, and durable handler replay.
— the description by AWS

AutoGineer summary

Written by AutoGineer from the skill’s own files, not by the author

This skill provides guidance and patterns for implementing durable, multi-step applications on AWS Lambda. It focuses on the replay model, which allows functions to maintain state across long-running executions—up to one year—by automatically checkpointing progress. The skill covers essential architectural patterns such as the saga pattern for error handling, wait/callback mechanisms for external system integration, and testing strategies using the local test runner. It emphasizes strict adherence to deterministic coding practices required by the replay model to ensure reliable execution.

What it does

  • Enables state persistence for long-running Lambda functions.
  • Provides patterns for implementing the saga pattern and compensating transactions.
  • Supports wait/callback patterns for integrating with external systems.
  • Offers guidance on testing durable functions locally and in the cloud.
  • Defines rules for deterministic code to prevent state corruption during replays.
  • Outlines requirements for qualified ARN invocation and IAM permissions.

When to use it

  • When building workflows that require execution times longer than standard Lambda timeouts.
  • When orchestrating multi-step processes that need to maintain state across interruptions.
  • When implementing reliable, fault-tolerant serverless integrations.
  • When managing complex state machines or human-in-the-loop approval processes.
  • When you need automatic retry logic and checkpointing for critical business processes.

Advantages

  • Resilient execution that survives infrastructure interruptions.
  • Simplified state management without external databases for simple workflows.
  • Native support for complex orchestration patterns like sagas and parallel execution.
  • Built-in replay-aware logging and error handling.
  • Local testing capabilities to validate complex workflow logic.

Usage examples

“How do I implement a multi-step workflow with a wait period in AWS Lambda?”
The agent provides a code example using context.step for logic and context.wait for the delay, ensuring the execution state is persisted correctly.
“Why is my durable function failing during replay?”
The agent helps diagnose non-deterministic code (like Date.now() or Math.random()) placed outside of steps, which causes state corruption.
“How do I handle errors in a long-running durable function?”
The agent explains the saga pattern and how to implement compensating transactions within steps to roll back state if a step fails.
“What are the requirements for invoking a durable Lambda function?”
The agent clarifies that durable functions must be invoked using a qualified ARN (version, alias, or $LATEST) and provides the corresponding AWS CLI command.

Install

  1. Download the skill as a ZIP:

    https://mp-staging.autogineer.com/agent-skills/aws/aws-lambda-durable-functions/download

  2. Unzip it into the cross-client skills folder of your project:

    mkdir -p .agents/skills && unzip aws-lambda-durable-functions.zip -d .agents/skills

Documentation by AWS

AWS Lambda durable functions

Build resilient multi-step applications and AI workflows that can execute for up to 1 year while maintaining reliable progress despite interruptions.

Works best with the AWS MCP server but is not required. All AWS interactions in this skill use standard AWS CLI commands that work in any environment with configured AWS credentials.

Critical Rules

Read these before writing any code. Each one is a constraint that will silently break a function if violated.

  1. Durable execution must be enabled at function creation time — it cannot be retrofitted. A new Lambda function must be created with durable execution turned on. Migrate the logic into the new function; do not attempt to install the SDK and wrap the handler of the existing function and expect it to work.

  2. Durable functions must be invoked with a qualified ARN — a specific version, an alias, or the literal $LATEST suffix. An unqualified function name will fail. See the Invocation Requirements section below for examples.

  3. Durable operations cannot be nested. You cannot call context.step(), context.wait(), or context.invoke() from inside another step's callback. Use context.runInChildContext() to group operations instead.

  4. All non-deterministic code must run inside steps. Date.now(), Math.random(), UUID generation, API calls, and database queries outside a step will produce different values on replay and corrupt execution state.

  5. Closure mutations are lost on replay - return values from steps

  6. Side effects outside steps repeat - use context.logger (replay-aware)

When to Load Reference Files

Load the appropriate reference file based on what the user is working on:

  • Getting started, basic setup, example, ESLint, or Jest setup -> see getting-started.md

  • Understanding replay model, determinism, or non-deterministic errors -> see replay-model-rules.md

  • Creating steps, atomic operations, or retry logic -> see step-operations.md

  • Waiting, delays, callbacks, external systems, or polling -> see wait-operations.md

  • Parallel execution, map operations, batch processing, or concurrency -> see concurrent-operations.md

  • Error handling, retry strategies, saga pattern, or compensating transactions -> see error-handling.md

  • Advanced error handling, timeout handling, circuit breakers, or conditional retries -> see advanced-error-handling.md

  • Testing, local testing, cloud testing, test runner, or flaky tests -> see testing-patterns.md

  • Deployment, CloudFormation, CDK, SAM, log groups, deploy, or infrastructure -> see deployment-iac.md

  • Advanced patterns, GenAI agents, completion policies, step semantics, or custom serialization -> see advanced-patterns.md

  • troubleshooting, stuck execution, failed execution, debug execution ID, execution history, execution error, why did my execution fail, execution timed out, callback not received, diagnose execution, or root cause execution -> see troubleshooting-executions.md

Quick Reference

Basic Handler Pattern

TypeScript:

import { withDurableExecution, DurableContext } from '@aws/durable-execution-sdk-js';

export const handler = withDurableExecution(async (event, context: DurableContext) => {
  const result = await context.step('process', async () => processData(event));
  return result;
});

Python:

from aws_durable_execution_sdk_python import durable_execution, DurableContext

@durable_execution
def handler(event: dict, context: DurableContext) -> dict:
    result = context.step(lambda _: process_data(event), name='process')
    return result
Python API Differences

The Python SDK differs from TypeScript in several key areas:

  • Steps: Use @durable_step decorator + context.step(my_step(args)), or inline context.step(lambda _: ..., name='...'). Prefer the decorator for automatic step naming.

  • Wait: context.wait(duration=Duration.from_seconds(n), name='...')

  • Exceptions: ExecutionError (permanent), InvocationError (transient), CallbackError (callback failures)

  • Testing: Use DurableFunctionTestRunner class directly - instantiate with handler, use context manager, call run(input=...)

Invocation Requirements

Durable functions require qualified ARNs (version, alias, or $LATEST):

# Valid
aws lambda invoke --function-name my-function:1 output.json
aws lambda invoke --function-name my-function:live output.json

# Invalid - will fail
aws lambda invoke --function-name my-function output.json

IAM Permissions

Your Lambda execution role MUST have the AWSLambdaBasicDurableExecutionRolePolicy managed policy attached. This includes:

  • lambda:CheckpointDurableExecution - Persist execution state

  • lambda:GetDurableExecutionState - Retrieve execution state

  • CloudWatch Logs permissions

Additional permissions needed for:

  • Durable invokes: lambda:InvokeFunction on target function ARNs

  • External callbacks: Systems need lambda:SendDurableExecutionCallbackSuccess and lambda:SendDurableExecutionCallbackFailure

Validation Guidelines

When writing or reviewing durable function code, ALWAYS check for these replay model violations:

  1. Non-deterministic code outside steps: Date.now(), Math.random(), UUID generation, API calls, database queries must all be inside steps

  2. Nested durable operations in step functions: Cannot call context.step(), context.wait(), or context.invoke() inside a step function — use context.runInChildContext() instead

  3. Closure mutations that won't persist: Variables mutated inside steps are NOT preserved across replays — return values from steps instead

  4. Side effects outside steps that repeat on replay: Use context.logger for logging (it is replay-aware and deduplicates automatically)

When implementing or modifying tests for durable functions, ALWAYS verify:

  1. All operations have descriptive names

  2. Tests get operations by NAME, never by index

  3. Replay behavior is tested with multiple invocations

  4. Use LocalDurableTestRunner for local testing

Security Considerations

  • Checkpoint data encryption: Execution state is persisted automatically. Enable KMS encryption on associated CloudWatch Log Groups to protect checkpointed data at rest.

  • Sensitive data in step results: Step return values are checkpointed and persisted. Do not return secrets, raw credentials, or PII from steps — store sensitive data in Secrets Manager or SSM Parameter Store and return references instead.

  • Input validation: Validate and sanitize event payloads at the handler entry point before passing data to steps.

  • Credential management: Retrieve secrets from AWS Secrets Manager or SSM Parameter Store within steps.

  • Callback payload validation: Data received via waitForCallback originates from external systems — validate and sanitize before processing.

  • Logging: Avoid DEBUG log level in non-development environments as it may expose step results and execution state. Enable CloudWatch Logs encryption with KMS.

Resources

Files

references/deployment-iac.md

Deployment with Infrastructure as Code

Deploy durable functions using CloudFormation, CDK, or SAM.

Requirements

All durable functions require:

  1. DurableConfig property on the function

  2. AWSLambdaBasicDurableExecutionRolePolicy attached to execution role

  3. Qualified ARN (version or alias) for invocation

AWS CloudFormation

template.yaml:

AWSTemplateFormatVersion: '2010-09-09'
Resources:
  DurableFunctionRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Version: '2012-10-17'
        Statement:
          - Effect: Allow
            Principal:
              Service: lambda.amazonaws.com
            Action: sts:AssumeRole
      ManagedPolicyArns:
        - arn:aws:iam::aws:policy/service-role/AWSLambdaBasicDurableExecutionRolePolicy

  DurableFunction:
    Type: AWS::Lambda::Function
    Properties:
      FunctionName: myDurableFunction
      Runtime: nodejs24.x  # or python3.14
      Handler: index.handler
      Role: !GetAtt DurableFunctionRole.Arn
      Code:
        ZipFile: |
          // Your durable function code
      DurableConfig:
        ExecutionTimeout: 3600        # Max execution time (seconds)
        RetentionPeriodInDays: 7      # How long to keep execution state
      Environment:
        Variables:
          LOG_LEVEL: INFO

  DurableFunctionVersion:
    Type: AWS::Lambda::Version
    Properties:
      FunctionName: !Ref DurableFunction

  DurableFunctionAlias:
    Type: AWS::Lambda::Alias
    Properties:
      FunctionName: !Ref DurableFunction
      FunctionVersion: !GetAtt DurableFunctionVersion.Version
      Name: live

Outputs:
  FunctionArn:
    Value: !GetAtt DurableFunction.Arn
  AliasArn:
    Value: !Ref DurableFunctionAlias

Deploy:

aws cloudformation deploy \
  --template-file template.yaml \
  --stack-name my-durable-function \
  --capabilities CAPABILITY_IAM

AWS CDK

TypeScript:

import * as cdk from 'aws-cdk-lib';
import * as lambda from 'aws-cdk-lib/aws-lambda';
import * as iam from 'aws-cdk-lib/aws-iam';

export class DurableFunctionStack extends cdk.Stack {
  constructor(scope: cdk.App, id: string, props?: cdk.StackProps) {
    super(scope, id, props);

    const durableFunction = new lambda.Function(this, 'DurableFunction', {
      runtime: lambda.Runtime.NODEJS_24_X,  // or PYTHON_3_14
      handler: 'index.handler',
      code: lambda.Code.fromAsset('lambda'),
      durableConfig: {
        executionTimeout: cdk.Duration.hours(1),
        retentionPeriod: cdk.Duration.days(7)
      },
      environment: {
        LOG_LEVEL: 'INFO'
      }
    });

    // CDK automatically adds checkpoint permissions when durableConfig is set

    // Create version and alias
    const version = durableFunction.currentVersion;
    const alias = new lambda.Alias(this, 'LiveAlias', {
      aliasName: 'live',
      version: version
    });

    // Output the qualified ARN
    new cdk.CfnOutput(this, 'FunctionAliasArn', {
      value: alias.functionArn
    });
  }
}

Deploy:

cdk deploy
CDK Custom Log Group Management

Best Practice: Explicitly create and manage CloudWatch Log Groups for better control over retention, cleanup, and costs.

import * as logs from 'aws-cdk-lib/aws-logs';
import * as iam from 'aws-cdk-lib/aws-iam';

// 1. Create explicit log group
const functionLogGroup = new logs.LogGroup(this, 'DurableFunctionLogGroup', {
  logGroupName: '/aws/lambda/myDurableFunction',
  retention: logs.RetentionDays.ONE_WEEK,
  removalPolicy: cdk.RemovalPolicy.DESTROY,  // Delete on stack destroy
});

// 2. Link to function
const durableFunction = new lambda.Function(this, 'DurableFunction', {
  runtime: lambda.Runtime.NODEJS_24_X,
  handler: 'index.handler',
  code: lambda.Code.fromAsset('lambda'),
  logGroup: functionLogGroup,  // Link to managed log group
  durableConfig: {
    executionTimeout: cdk.Duration.hours(1),
    retentionPeriod: cdk.Duration.days(7)
  }
});

// 3. Add durable execution policy (required with explicit log groups)
durableFunction.role?.addManagedPolicy(
  iam.ManagedPolicy.fromAwsManagedPolicyName(
    'service-role/AWSLambdaBasicDurableExecutionRolePolicy'
  )
);

Benefits:

  • Explicit Cleanup: removalPolicy: cdk.RemovalPolicy.DESTROY ensures log groups are deleted when stack is destroyed

  • Custom Retention: Set retention periods matching compliance/debugging needs

  • Predictable Naming: Control exact log group name

  • Cost Control: Avoid accumulating costs from orphaned log groups

When to use:

  • ✅ Production environments where log retention policies must be enforced

  • ✅ Development/test environments where automatic cleanup saves costs

  • ✅ Multi-function stacks where consistent log management is needed

Important: Don't forget to add AWSLambdaBasicDurableExecutionRolePolicy when using explicit log groups.

AWS SAM

template.yaml:

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31

Globals:
  Function:
    Timeout: 900
    MemorySize: 512

Resources:
  DurableFunction:
    Type: AWS::Serverless::Function
    Properties:
      FunctionName: myDurableFunction
      Runtime: nodejs24.x  # or python3.14
      Handler: index.handler
      CodeUri: ./src
      DurableConfig:
        ExecutionTimeout: 3600
        RetentionPeriodInDays: 7
      Policies:
        - arn:aws:iam::aws:policy/service-role/AWSLambdaBasicDurableExecutionRolePolicy
      AutoPublishAlias: live
      Environment:
        Variables:
          LOG_LEVEL: INFO

Outputs:
  FunctionArn:
    Value: !GetAtt DurableFunction.Arn
  AliasArn:
    Value: !Ref DurableFunction.Alias

Deploy:

sam build
sam deploy --guided

Durable Invokes

For functions that invoke other durable functions:

CloudFormation:

DurableFunctionRole:
  Type: AWS::IAM::Role
  Properties:
    AssumeRolePolicyDocument:
      Version: '2012-10-17'
      Statement:
        - Effect: Allow
          Principal:
            Service: lambda.amazonaws.com
          Action: sts:AssumeRole
    ManagedPolicyArns:
      - arn:aws:iam::aws:policy/service-role/AWSLambdaBasicDurableExecutionRolePolicy
    Policies:
      - PolicyName: InvokeOtherFunctions
        PolicyDocument:
          Version: '2012-10-17'
          Statement:
            - Effect: Allow
              Action:
                - lambda:InvokeFunction
              Resource:
                - !GetAtt TargetFunction.Arn
                - !Sub '${TargetFunction.Arn}:*'  # For versions/aliases

CDK:

const targetFunction = new lambda.Function(this, 'TargetFunction', {
  // ... configuration
});

const orchestratorFunction = new lambda.Function(this, 'OrchestratorFunction', {
  // ... configuration with durableConfig
});

// Grant invoke permission
targetFunction.grantInvoke(orchestratorFunction);

External Callbacks

For external systems to send callbacks:

IAM Policy:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "lambda:SendDurableExecutionCallbackSuccess",
        "lambda:SendDurableExecutionCallbackFailure",
        "lambda:SendDurableExecutionCallbackHeartbeat"
      ],
      "Resource": "arn:aws:lambda:us-east-1:123456789012:function:myDurableFunction:*"
    }
  ]
}

Environment Configuration

Development:

DurableFunction:
  Type: AWS::Lambda::Function
  Properties:
    DurableConfig:
      ExecutionTimeout: 900          # 15 minutes
      RetentionPeriodInDays: 1       # Short retention
    Environment:
      Variables:
        LOG_LEVEL: DEBUG             # Use INFO or higher in non-dev — DEBUG may expose step results and execution state
        ENVIRONMENT: development

Production:

DurableFunction:
  Type: AWS::Lambda::Function
  Properties:
    DurableConfig:
      ExecutionTimeout: 86400        # 24 hours
      RetentionPeriodInDays: 30      # Long retention
    Environment:
      Variables:
        LOG_LEVEL: INFO
        ENVIRONMENT: production

Multi-Environment Deployment

CDK with Stages:

const app = new cdk.App();

new DurableFunctionStack(app, 'DurableFunction-Dev', {
  env: { account: '123456789012', region: 'us-east-1' },
  stage: 'dev',
  durableConfig: {
    executionTimeout: cdk.Duration.minutes(15),
    retentionPeriod: cdk.Duration.days(1)
  }
});

new DurableFunctionStack(app, 'DurableFunction-Prod', {
  env: { account: '123456789012', region: 'us-east-1' },
  stage: 'prod',
  durableConfig: {
    executionTimeout: cdk.Duration.hours(24),
    retentionPeriod: cdk.Duration.days(30)
  }
});

Invocation Examples

Critical Requirements

⚠️ Important Invocation Rules:

  1. Qualified Function Name Required: You MUST provide a qualified function name with version, alias, or :$LATEST

  2. Idempotency with durable-execution-name: Use this parameter to ensure the same execution name always refers to the same execution

  3. Binary Format: Use --cli-binary-format raw-in-base64-out to avoid base64 encoding issues

Synchronous Invocation (RequestResponse)

Synchronous invocation waits for the function to complete and returns the result immediately. Suitable for short workflows.

aws lambda invoke \
  --function-name 'myDurableFunction:$LATEST' \
  --invocation-type RequestResponse \
  --durable-execution-name "execution-123" \
  --payload '{"userId":"12345","action":"process"}' \
  --cli-binary-format raw-in-base64-out \
  --output json \
  response.json

# View the response
cat response.json

When to use RequestResponse:

  • Short-running workflows (under 15 minutes total)

  • When you need the result immediately

  • Interactive applications requiring synchronous responses

Asynchronous Invocation (Event)

Asynchronous invocation returns immediately with the execution ID. Ideal for long-running workflows.

aws lambda invoke \
  --function-name 'myDurableFunction:$LATEST' \
  --invocation-type Event \
  --durable-execution-name "background-task-456" \
  --payload '{"orderId":"ORD-789","amount":99.99}' \
  --cli-binary-format raw-in-base64-out \
  --output json \
  response.json

# Response contains execution ID, not the result
cat response.json

When to use Event:

  • Long-running workflows (hours, days, or longer)

  • Background processing tasks

  • Workflows with wait operations or human-in-the-loop steps

Idempotency with durable-execution-name

The --durable-execution-name parameter ensures that the same execution is never created twice:

# First invocation - creates new execution
aws lambda invoke \
  --function-name 'myDurableFunction:$LATEST' \
  --invocation-type RequestResponse \
  --durable-execution-name "order-processing-ORD-123" \
  --payload '{"orderId":"ORD-123"}' \
  --cli-binary-format raw-in-base64-out \
  response.json

# Second invocation with same execution name - returns existing execution result
aws lambda invoke \
  --function-name 'myDurableFunction:$LATEST' \
  --invocation-type RequestResponse \
  --durable-execution-name "order-processing-ORD-123" \
  --payload '{"orderId":"ORD-123"}' \
  --cli-binary-format raw-in-base64-out \
  response.json
Using Specific Function Versions

Durable functions require qualified ARNs (version, alias, or $LATEST):

# ✅ Invoke specific version
aws lambda invoke \
  --function-name 'myDurableFunction:1' \
  --invocation-type RequestResponse \
  --durable-execution-name "versioned-exec-1" \
  --payload '{"test":"data"}' \
  --cli-binary-format raw-in-base64-out \
  response.json

# ✅ Invoke using alias
aws lambda invoke \
  --function-name 'myDurableFunction:live' \
  --invocation-type RequestResponse \
  --durable-execution-name "my-exec-1" \
  --payload '{"test":"data"}' \
  --cli-binary-format raw-in-base64-out \
  response.json

# ❌ Unqualified - will fail!
aws lambda invoke \
  --function-name 'myDurableFunction' \
  --payload '{"test":"data"}' \
  response.json
# Error: Durable execution requires qualified function identifier

Monitoring and Observability

CloudWatch Logs:

DurableFunction:
  Type: AWS::Lambda::Function
  Properties:
    # ... other properties
    LoggingConfig:
      LogFormat: JSON
      LogGroup: !Ref DurableFunctionLogGroup

DurableFunctionLogGroup:
  Type: AWS::Logs::LogGroup
  Properties:
    LogGroupName: /aws/lambda/myDurableFunction
    RetentionInDays: 7

CloudWatch Alarms:

DurableFunctionErrorAlarm:
  Type: AWS::CloudWatch::Alarm
  Properties:
    AlarmName: DurableFunction-Errors
    MetricName: Errors
    Namespace: AWS/Lambda
    Statistic: Sum
    Period: 300
    EvaluationPeriods: 1
    Threshold: 5
    ComparisonOperator: GreaterThanThreshold
    Dimensions:
      - Name: FunctionName
        Value: !Ref DurableFunction

Best Practices

  1. Always use qualified ARNs (versions or aliases) for invocation

  2. Set appropriate execution timeouts based on workflow duration

  3. Configure retention periods to balance cost and debugging needs

  4. Use aliases for production deployments

  5. Grant minimal IAM permissions - only what's needed

  6. Enable structured logging (JSON format)

  7. Set up CloudWatch alarms for errors and throttles

  8. Use environment variables for configuration

  9. Deploy to multiple environments (dev, staging, prod)

  10. Version your infrastructure code alongside function code

Common issues

Function Not Durable

Issue: Function executes but doesn't checkpoint.

Solution: Verify DurableConfig is set and role has checkpoint permissions.

Invocation Fails with "Unqualified ARN"

Issue: InvalidParameterValueException: Durable execution requires qualified function identifier

Solution: Use version, alias, or $LATEST:

# ✅ Correct
aws lambda invoke --function-name myFunction:live ...
aws lambda invoke --function-name myFunction:1 ...

# ❌ Wrong
aws lambda invoke --function-name myFunction ...
Checkpoint Permission Denied

Issue: AccessDeniedException: User is not authorized to perform: lambda:CheckpointDurableExecution

Solution: Add AWSLambdaBasicDurableExecutionRolePolicy to execution role.

Requirements and compatibility

Works with: Claude Code, Claude apps, OpenAI Codex, GitHub Copilot, Cursor, Gemini CLI, Kiro, OpenCode, Goose, Amp, Roo Code, JetBrains Junie, Factory Droid, Devin (ex-Windsurf), Mistral Vibe, OpenHands, Letta

“Works with” means the tool reads the open Agent Skills format; a skill written for one tool may use features others lack.

Needs: Needs an MCP server, Needs a command-line tool, Needs Python

Security

What our scanner noticed· Low risk

  • Instructions that use the network

A static scan is not a guarantee. Skills are third-party content: review a skill before you let an agent use it.

Attribution and licence

Published by
AWS
Publisher
AWS (Official)
Source
aws/agent-toolkit-for-aws · skills/specialized-skills/serverless-skills/aws-lambda-durable-functions · commit 0a218f8
Licence
Apache License 2.0 (redistribution allowed)
  • LICENSE (added by AutoGineer from LICENSE)
  • NOTICE (added by AutoGineer from NOTICE)
  • ATTRIBUTION.md (written by AutoGineer)
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