[Schema][Client][Server] Add the Tasks extension (SEP-2663) - #428
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[Schema][Client][Server] Add the Tasks extension (SEP-2663)#428chr-hertel wants to merge 1 commit into
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`io.modelcontextprotocol/tasks`: `Task` and `TaskStatus`, `ResultType::Task`,
the `CreateTaskResult` / `TaskResult` wire shapes, the `tasks/get` /
`tasks/update` / `tasks/cancel` handlers behind `TasksExtension`,
`TaskStoreInterface` with in-memory and PSR-16 stores, and a `TaskContext`
handed to handlers for creating tasks — refused with -32021 for a client that
did not declare the extension.
The core stays extension-agnostic: `MethodProvidingExtensionInterface` and
`ArgumentProvidingExtensionInterface` let an extension register its messages,
handlers and injectable handler arguments; the core handlers pass any
`ResultInterface` through; a `MissingRequiredClientCapabilityException` from
handler code becomes -32021; `Client::request()` sends any request. On the
client, `TaskClient` speaks the extension. Covered end to end by an integration
test against a stdio fixture server. Extension settings serialize as `{}`
rather than `[]` when empty.
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Squashed WIP: the modern (SEP-2575) stateless lifecycle end to end - server dispatcher, per-era wire codec, standard header validation, multi round-trip requests, subscriptions, cache policy, the generic extensions framework, and a client that speaks it. Tasks (SEP-2663) is carved out to modelcontextprotocol#428. To be decomposed before review.
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Adds
io.modelcontextprotocol/tasks(SEP-2663), server and client, without the core learning about it.Generic seams (core, extension-agnostic)
MethodProvidingExtensionInterface: an extension's message classes go to theMessageFactory, its handlers to the server, viaBuilder::enableExtension().ArgumentProvidingExtensionInterface: an extension hands handlers objects of its own — injected byReferenceHandlerlike aRequestContext, left out of generated input schemas bySchemaGenerator.CallToolHandler/GetPromptHandler/ReadResourceHandlerpass anyResultInterfacea handler returns through untouched.MissingRequiredClientCapabilityExceptionthrown from handler code is answered as-32021(handlers andProtocol).Client::request()sends any request; the typed API is unchanged.Response/RequestHandlerInterfacecovariant in their result type; extension settings serialize as{}rather than[]when empty.Tasks extension (on those seams)
Task(fromArray()),TaskStatus,ResultType::Task,CreateTaskResult/TaskResult(flat),TasksGet/Update/CancelRequest.TasksExtension(Server\Task):tasks/get/tasks/update/tasks/cancelhandlers gated with-32021,TaskStoreInterfacewithInMemoryTaskStore(bounded) andPsr16TaskStore, and aTaskContextprovided to handlers:isSupported(),create()(stores before handing out; refuses undeclared clients),getStore(). Advancing a task is the application's job.Client\Builder::enableExtension(new TasksExtension())declares it;Client\Task\TaskClientspeaks it —callTool()/getPrompt()/readResource()returningCreateTaskResultwhen the server answered with a task,get()/update()/cancel().tests/Integration/TasksTestruns the loop against a stdio fixture: handle → poll → completed,input_required→update→ completed, failed, cancel, both-32021refusals, sync fallback, unknown task, prompt-as-task.docs/extensions.md(server and client), CHANGELOG.Design decisions vs. the original issue sketches are recorded in the rewritten #345–#349.