[psp65]

What behavior changes?

Bumps VERSION from 1.7.0 to 1.7.1 and adds the 1.7.1 entry to CHANGELOG.md. There are no code changes.

The release covers 52 commits since 1.7.0 (1.7.0..d62ebebbe, 35 PRs). The main reason for it is three MCP fixes:

• Forward remote MCP calls in the protocol the remote negotiated #1386: remote MCP calls are forwarded with the protocol version that the remote negotiated (fixes mcp-server: remote tools/call and prompts/get are forwarded with the caller's protocol version instead of the remote's #1384)
• Add option to restrict the MCP protocol versions a server serves #1385: a server can restrict which MCP protocol versions it serves (mitigates MCP server: list-change notifications are lost for clients that negotiate 2026-07-28 (no subscriptions/listen) #1383)
• Ignore the body of an HTTP notification response #1413: the body of an HTTP response to a notification is ignored (fixes MCP server: HttpMcpClient fails to initialize when a notification is accepted with a 202 body #1412)

Why is this change needed?

Consumers of the MCP server need these fixes released. Clients are moving their default to MCP protocol 2026-07-28, and on 1.7.0, tool calls to remotes that validate the MCP-Protocol-Version header fail. Remotes that answer a notification with a 202 and a body also fail to initialize.

How was this validated?

Release preflight from the internal release process, run on d62ebebbe with VERSION=1.7.1:

• ./gradlew clean build publish passed, with :client:client-waiters:test skipped because TestWaiters.testWaiterTimesOut is flaky (see below).
• The internal import and validation steps passed for all 71 published modules (bom skipped as usual). No new modules need onboarding.
• Internal dry-run builds of downstream consumers passed for the development version set. The full downstream dry-run is in progress; a dry-run of the earlier ba1901282 passed. Build links are in the internal tracking ticket.

This commit sits directly on d62ebebbe, so the merged tree is exactly what was dry-run plus VERSION and CHANGELOG.md.

What should reviewers focus on?

The CHANGELOG entry is a best-effort draft. Please correct anything that's wrong.

1. Release date: the heading says ## 1.7.1 (TBD). Set the date before merging. 1.7.0 used the M/D/YYYY format.
2. Breaking Changes: the draft has no Breaking Changes section. These changes may deserve one:
   • Add output buffer pooling #1410: output buffer pooling is on by default. Reading a pooled request body after its call completes throws IllegalStateException, and close() on a pooled body does nothing. A custom ClientTransport that keeps reading the body after it returns must call PooledDataStream.abandon(). Each built-in protocol now owns its own pool, which can keep up to about 4 MB of arrays per size class.
   • Skip auth scheme property merge when the option carries no overrides #1408: when an auth option has no overrides, the scheme's properties go straight to the Signer/IdentityResolver and can be shared across calls. Implementations that mutated them may break.
3. Other behavior changes that are in normal sections:
   • Improve SigV4 performance #1409: SigV4 now canonicalizes header values as UTF-8, where 1.7.0 narrowed each char to one byte. Signatures change for non-ASCII header values. This is probably a bug fix, but the PR doesn't call it one.
   • Coerce untyped numbers to modeled types in StructDocument #1419: StructDocument number coercion uses narrowing casts, so out-of-range or fractional values are truncated silently.
   • Add schema extensions for event-stream serde  #1380: the event-stream encoder and decoder require the EventStreamSchemaExtensions service provider. Shaded JARs that drop META-INF/services will fail.
   • Honor typed oneOf documents and tighten timestamp parsing #1378: MCP epoch-seconds members no longer accept numeric strings, which 1.7.0 accepted after Support oneOf defaults for missing discriminators #1376.
   • Improve perf of UserAgentPlugin #1402: aws.userAgentAppId is now honored, and the app ID is resolved once per client build.
   • Fix identity resolver lookup ignoring user-supplied static identities #1392: resolver lookup now matches assignable types, so a client with several matching resolvers may pick a different one.
   • Optimize endpoint resolution #1417: the bytecode interpreter in the endpoint rules engine is replaced by compiled node trees. Steady-state resolution is 50–56% faster. The first resolution down a rule path is about 1 µs slower.
4. Omitted from the entry:
   • the dependency bumps Bump the gradle group across 1 directory with 43 updates #1381 and Bump the gradle group with 12 updates #1414. Netty moves to 4.2.18/4.2.19, which turns on stricter HTTP/2 header validation by default and may deserve a line for server-netty users.
   • Fixed http payload deserialization #1391, which fixes a regression from Generate the HTTP binding pass at runtime #1358 that never shipped.
   • benchmark-only and test-only PRs: Handle expected-failure event stream request tests #1379, Normalize JSON benchmark bodies. #1388, Add cross-SDK e2e benchmark harness, fixture server and metal runner #1395, Simplify e2e-benchmark harness #1398, Add baseline benchmark results from Feb 11 2026 #1399, Normalize Json in e2e-benchmarks too #1407, Add latest benchmark data #1411.
5. Flaky tests seen in local full builds. Both passed in CI, but they could fail the Catapult release build:
   • TestWaiters.testWaiterTimesOut: failed 2 of 3 isolated reruns. Waiter.waitToRetry checks remainingTime < 0. At exactly 0 it retries with no delay and the mock runs out of responses, so the check should probably be <= 0.
   • RestJson1ProtocolTests › UnmodeledProtocolError in aws-client-restjson:integ-native: failed once under a parallel full build and passed when rerun alone.
6. Squash-merge title: please keep it as Bump version to 1.7.1. update_release_tags finds the release commit by that subject.

Commit → PR mapping (52 commits)

Commit	PR	Status	Section, or reason if omitted
d62ebebbe	#1413	Included	Bug Fixes (MCP notification body)
8e892b96c	#1380	Included	Improvements (event streams)
4a8bea126	#1419	Included	Bug Fixes (StructDocument numbers)
70c0f918e	#1414	Omitted	Dependabot dependency bump
4bb3eaad3	#1417	Included	Improvements (endpoint resolution)
9341050c4	#1417	Included	Improvements (endpoint resolution)
ac39c17af	#1417	Included	Improvements (endpoint resolution)
8820b722c	#1417	Included	Improvements (endpoint resolution)
b386e9aca	#1417	Included	Improvements (endpoint resolution)
7aa78c168	#1417	Included	Improvements (endpoint resolution)
2ac9166c1	#1417	Included	Improvements (endpoint resolution)
be145fcab	#1417	Included	Improvements (endpoint resolution)
b11fd4417	#1417	Included	Improvements (endpoint resolution)
ec12fbba2	#1417	Included via PR	Benchmark-only commit inside #1417
f12e11a6b	#1417	Included	Improvements (caches aws.partition, plus benchmark)
51bc74f04	#1417	Included via PR	Benchmark-only commit inside #1417
67e1f063c	#1417	Included	Improvements (endpoint resolution)
473877a37	#1417	Included	Improvements (endpoint resolution)
ba1901282	#1411	Omitted	Benchmark data and scripts only
d3dd17843	#1385	Included	Features (MCP protocol version restriction)
304e02511	#1410	Included	Improvements (output buffer pooling)
0e88c8e76	#1410	Included	Improvements (output buffer pooling)
c62499ffd	#1409	Included	Improvements (SigV4)
e839b1b49	#1386	Included	Bug Fixes (MCP forwarded protocol version)
156e5939d	#1405	Included	Improvements (client overhead)
2fd0f976f	#1400	Included	Improvements (schema)
2e6f15e60	#1406	Included	Improvements (client overhead)
0f0bedf59	#1402	Included	Bug Fixes (User-Agent) and Improvements
ebe122c96	#1401	Included	Improvements (client overhead)
1f68318ce	#1408	Included	Improvements (client overhead)
534de7824	#1403	Included	Improvements (schema)
500cc0d5c	#1399	Omitted	Benchmark data only
298b5d799	#1404	Included	Improvements (client overhead)
d5bbff7be	#1407	Omitted	Benchmark harness only
83331aaf1	#1398	Omitted	Benchmark harness only
057770a2c	#1395	Omitted	Benchmark harness only
8f038fd5a	#1395	Omitted	Benchmark harness only
8c5cf2907	#1393	Included	Improvements (ASCII string intrinsics)
eb23fa19f	#1392	Included	Bug Fixes (static identity lookup)
142eecf4d	#1389	Included	Improvements (floating point)
852d8ab7a	#1388	Omitted	Benchmark-only change
9326586ab	#1387	Included	Improvements (floating point)
cb0406f98	#1391	Omitted	Tests for the #1391 regression fix
728090069	#1391	Omitted	Fixes regression from #1358 that never shipped
4e51ae1ed	#1378	Included	Bug Fixes (MCP typed oneOf, timestamps)
9a262167c	#1354	Included	Features (runtime codegen)
225ebe17b	#1358	Included	Features (runtime codegen)
27ff34d36	#1353	Included	Features (runtime codegen)
f7216c206	#1382	Included via PR	Spotless formatting commit inside #1382
2c9b5e49c	#1382	Included	Bug Fixes (Schemas method size limit)
5d0812981	#1381	Omitted	Dependabot dependency bump
d70d5a564	#1379	Omitted	Test-only (protocol-test-harness)

Additional Links

• Related: MCP server: list-change notifications are lost for clients that negotiate 2026-07-28 (no subscriptions/listen) #1383, mcp-server: remote tools/call and prompts/get are forwarded with the caller's protocol version instead of the remote's #1384, MCP server: HttpMcpClient fails to initialize when a notification is accepted with a 202 body #1412, Support subscriptions/listen on the stdio MCP server #1397 (subscriptions/listen, not included)

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

🤖 AI-assisted PR description 🤖

[psp65]

Closing at the maintainers' request: the next release will be 1.8.0, and the Smithy team will handle the version bump. Feel free to reuse the CHANGELOG draft and the reviewer notes in this PR's description.