[Client] Speak the 2026-07-28 lifecycle - #456
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chr-hertel
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soyuka
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August 18, 2026 19:10
On that revision the client opens with server/discover instead of initialize, stamps each request's _meta with the protocol version, its own capabilities and client info, and sends the standard Mcp-Method / Mcp-Name / Mcp-Param-* headers an intermediary routes on. ToolCatalog is what knows, from the tool list, which arguments a call has to mirror. An input_required result is answered rather than surfaced: InputRequestResolver asks the host's elicitation, sampling and roots handlers and retries the same request carrying inputResponses and the requestState the server sent. McpHeader holds the header names and the =?base64?…?= sentinel, so the two sides no longer keep their own copies of the same rules.
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Pull request overview
Adds client support for the 2026-07-28 stateless MCP lifecycle.
Changes:
- Adds discovery, request envelopes, protocol headers, and version reconciliation.
- Resolves multi-round-trip input requests automatically.
- Shares header validation rules and adds dual-era/conformance coverage.
Reviewed changes
Copilot reviewed 24 out of 24 changed files in this pull request and generated 4 comments.
Show a summary per file
| File | Description |
|---|---|
CHANGELOG.md |
Documents client lifecycle support. |
src/Client.php |
Integrates tool catalog validation. |
src/Client/Protocol.php |
Implements modern lifecycle and retries. |
src/Client/Stateless/HeaderFactory.php |
Generates protocol headers. |
src/Client/Stateless/InputRequestResolver.php |
Resolves embedded input requests. |
src/Client/Stateless/RequestEnvelope.php |
Stamps modern request metadata. |
src/Client/Stateless/ToolCatalog.php |
Tracks tool header annotations. |
src/Client/Transport/HeaderAwareTransportInterface.php |
Defines per-message header callbacks. |
src/Client/Transport/HttpTransport.php |
Sends generated HTTP headers. |
src/Schema/Request/DiscoverRequest.php |
Models server/discover. |
src/Schema/Tool.php |
Delegates annotation validation. |
src/Schema/Wire/McpHeader.php |
Centralizes header rules. |
src/Server/Stateless/StandardHeaderValidator.php |
Uses shared header utilities. |
examples/server/client-communication/ClientAwareService.php |
Converts examples to MRTR. |
examples/server/elicitation/ElicitationHandlers.php |
Supports elicitation across eras. |
tests/Conformance/client.php |
Adds modern conformance scenarios. |
tests/Integration/DualEraElicitationTest.php |
Tests elicitation in both eras. |
tests/Integration/DualEraExampleTestCase.php |
Provides dual-era test infrastructure. |
tests/Integration/HandshakeTest.php |
Updates lifecycle expectations. |
tests/Unit/Client/ProtocolTest.php |
Tests modern protocol initialization. |
tests/Unit/Client/Stateless/HeaderFactoryTest.php |
Tests generated headers. |
tests/Unit/Client/Stateless/InputRequestResolverTest.php |
Tests input resolution. |
tests/Unit/Client/Stateless/ToolCatalogTest.php |
Tests catalog behavior. |
tests/Unit/Schema/Wire/McpHeaderTest.php |
Tests shared header encoding. |
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| return null; | ||
| } | ||
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||
| return self::isSafe($rendered) ? $rendered : self::wrap($rendered); |
| // between rounds. | ||
| $payload['params'] = [ | ||
| ...($payload['params'] ?? []), | ||
| 'inputResponses' => $this->inputRequests->resolve($asked), |
| ); | ||
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| $result = $clientGateway->sample($prompt, 350, 90, ['temperature' => 0.5]); | ||
| $result = $context->getInputContext()?->samplingResult('recommendation'); |
| @@ -80,37 +128,65 @@ public function __construct( | |||
| public function connect(TransportInterface $transport, Configuration $config): void | |||
| { | |||
| $this->transport = $transport; | |||
Drop stale expected-failure entries the new client fixture now passes. Copilot review: fix McpHeader round-trip for a wrapper-shaped literal, encode empty/numeric-keyed inputResponses as a JSON object, stop the incident example repeating side effects on MRTR retry, and reset ToolCatalog on reconnect instead of carrying the previous server's verdicts.
PHP_CLI_SERVER_WORKERS does not reliably fork multiple php -S workers there (php/php-src#9400), reproducing the single-worker deadlock the extra workers exist to avoid.
This was referenced Aug 19, 2026
chr-hertel
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2026-07-28
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Stacked on #455. This is the client half of the revision — with it, both sides of the SDK speak 2026-07-28.
Clientopens withserver/discoverinstead ofinitializeon that revision, stamps each request's_metawith the protocol version, its own capabilities and client info, and sends the standardMcp-Method/Mcp-Name/Mcp-Param-*headers an intermediary routes on.Mcp\Client\Stateless\ToolCatalogis what knows, from the tool list, which arguments a call has to mirror.An
input_requiredresult is answered rather than surfaced:InputRequestResolverasks the host's elicitation, sampling and roots handlers and retries the same request carryinginputResponsesand therequestStatethe server sent.One refactor to already-merged code.
Mcp\Schema\Wire\McpHeaderholds the header names and the=?base64?…?=sentinel both sides share. Thex-mcp-headerannotation rules from #441 move there too, asMcpHeader::checkAnnotations()/annotations(), andTooldelegates to them. The client needs those rules for a schema a peer sent, which the private methods onToolcould not serve; the rules themselves are unchanged, andToolHeaderAnnotationTeststill covers them throughTool.Cross-fork PRs can only target
main, so this diff also carries its ancestors until they merge. Only the last commit(s) belong to this PR — GitHub's "Commits" tab separates them.