AWS SDK Knowledge Patch

Covers AWS SDK changes from 2024-12 through 2026-03. Applies to JS v3 ~3.600+, boto3 ~1.34+, aws-sdk-go-v2 ~1.26+, CDK v2 ~2.140+.

Index

Topic	Reference	Key features
S3 checksums & vectors	references/s3-checksums-and-vectors.md	Default CRC checksums, CRC64NVME, full-object multipart checksums, S3 Vectors service
Lambda Durable Functions	references/lambda-durable-functions.md	Checkpoint-and-replay, @durable_step, wait/callback, idempotency
Bedrock AgentCore	references/bedrock-agentcore.md	Runtime deployment, memory client, identity/OAuth2, CLI
CDK & SDK config	references/cdk-and-sdk-config.md	CDK Mixins .with(), SigV4a auth scheme preference, STS regional default, SDK lifecycle

---

S3 Default Checksums (Dec 2024) — Breaking Change

SDKs now compute CRC checksums on every upload by default. S3 also computes server-side checksums on all uploads.

New algorithm: CRC64NVME. Default algorithms vary by SDK:

SDK	Default algorithm
CLI, C++, Rust	CRC64NVME
Go, Java, JS, Kotlin, .NET, PHP, Python, Ruby	CRC32

Config settings:

Setting	Env var	Default
request_checksum_calculation	AWS_REQUEST_CHECKSUM_CALCULATION	WHEN_SUPPORTED
response_checksum_validation	AWS_RESPONSE_CHECKSUM_VALIDATION	WHEN_SUPPORTED

Multipart uploads now support ChecksumType='FULL_OBJECT' for a single whole-object checksum instead of per-part composites.

See references/s3-checksums-and-vectors.md for full examples.

S3 Vectors (GA Dec 2025)

New S3 service for storing/querying vector embeddings. Separate from regular S3 buckets.

aws s3vectors create-vector-bucket --vector-bucket-name my-vectors
aws s3vectors create-index \
    --vector-bucket-name my-vectors \
    --index-name my-index \
    --data-type float32 --dimension 1024 \
    --distance-metric cosine \
    --metadata-configuration "nonFilterableMetadataKeys=text_chunk"

Supports cosine and euclidean distance. Up to 2B vectors/index, 50 metadata keys/vector (10 non-filterable). Integrates with Bedrock Knowledge Bases and OpenSearch.

See references/s3-checksums-and-vectors.md for query examples.

Lambda Durable Functions (Dec 2025)

Checkpoint-and-replay execution for Lambda. Must be enabled at function creation time (cannot be added later). Open-source SDK.

from aws_durable_execution_sdk_python import (
    DurableContext, StepContext, durable_execution, durable_step,
)
from aws_durable_execution_sdk_python.config import Duration, StepConfig, CallbackConfig

@durable_step
def my_step(step_context: StepContext, data: str) -> dict:
    return {"result": data}

@durable_execution
def lambda_handler(event: dict, context: DurableContext) -> dict:
    result = context.step(my_step(event["data"]))
    context.wait(Duration.from_minutes(5))  # suspends without compute charges
    return result

Supports JS/TS (Node.js 22/24) and Python (3.13/3.14). See references/lambda-durable-functions.md for callbacks and retry strategies.

Bedrock AgentCore (GA Oct 2025)

Enterprise services for deploying AI agents at scale. Framework-agnostic (Strands, LangGraph, etc.).

from bedrock_agentcore.runtime import BedrockAgentCoreApp
app = BedrockAgentCoreApp()

@app.entrypoint
def invoke(payload):
    return agent(payload.get("prompt"))

Install: pip install bedrock-agentcore bedrock-agentcore-starter-toolkit CLI: agentcore configure, agentcore launch [--local], agentcore invoke.

See references/bedrock-agentcore.md for memory client, identity, and full API.

CDK Mixins (GA Mar 2026)

Composable, reusable abstractions for any CDK construct via .with() syntax:

const bucket = new s3.CfnBucket(this, 'Bucket').with(
  AutoDelete(),
  Encryption(),
  Versioning(),
  BlockPublicAccess(),
);
// Apply compliance policies across a scope:
Mixins.of(this).add(/* resource type or path pattern filtering */);

See references/cdk-and-sdk-config.md for details.

Auth Scheme Preference (SigV4a)

New config for cross-region signing (e.g., multi-region access points):

# ~/.aws/config
[default]
auth_scheme_preference = sigv4a, sigv4
sigv4a_signing_region_set = us-east-1, eu-west-1

Env vars: AWS_AUTH_SCHEME_PREFERENCE, AWS_SIGV4A_SIGNING_REGION_SET.

SDK Version Lifecycle

SDK	Maintenance	End of Support	Migrate To
JS v2	Sep 2024	Sep 2025	JS v3
Go v1	Jul 2024	Jul 2025	Go v2
.NET v3	Mar 2026	Jun 2026	.NET v4 (GA Apr 2025)

JS v3 Node.js: Follows Node.js release + 8 months. Node.js 18 dropped Jan 2026 (requires 20+). Node.js 20 drops Jan 2027.

Python (boto3): 6-month grace after PSF EOL. Python 3.9 drops Apr 2026, 3.10 drops Apr 2027.

SDK Default Changes (July 2025)

• STS endpoint: Python, PHP, C++, .NET, PowerShell switch to regional default (was global)
• Retry strategy: Switch to standard (token-bucket throttling) delayed — AWS found concerns, will reschedule

Reference Files

File	Contents
s3-checksums-and-vectors.md	Default checksums, CRC64NVME, multipart full-object checksums, S3 Vectors API
lambda-durable-functions.md	Durable execution SDK, steps, wait/callback, retry strategies
bedrock-agentcore.md	Runtime deployment, memory client, identity, CLI commands
cdk-and-sdk-config.md	CDK Mixins, SigV4a, STS regional default, SDK lifecycle dates