* [Schema][Server] Close the 2025-11-25 schema gaps and add the 2026-07-28 surface
Ports the type definitions this SDK still misses outside of sampling tool use,
which #409 and #420 already cover. Every addition is optional and defaults to
current behaviour, so a connection negotiated on an older revision is
unaffected.
From 2025-11-25, elicitation gains modes. ElicitationMode splits `form` —
build a form from the requested schema — from `url`, which sends the user out
of band and returns only the accept/decline/cancel outcome. That is why
requestedSchema becomes optional and `url` appears beside it.
ClientCapabilities learns the matching sub-capabilities, where an
`elicitation` naming no mode declares form, the only shape that existed
before. Icon gains `theme` from the same revision, and Implementation gains
the `title` BaseMetadata has carried since 2025-06-18.
From 2026-07-28, schemas loosen where the revision loosens them: SEP-2106
drops the object-only restriction, so Tool::outputSchema may describe any JSON
value and CallToolResult::structuredContent follows.
The same revision defines three error codes (-32020 header mismatch, -32021
missing required client capability, -32022 unsupported protocol version).
ProtocolVersionMiddleware switches to the last of them, so a rejected version
carries the supported set as structured data the client can retry from rather
than only as prose.
* [Schema] Reject what the 2026-07-28 types cannot represent
`Implementation::title` reached the typed constructor unchecked, so malformed
wire data raised a TypeError instead of InvalidArgumentException.
`ToolUseContent::input` accepted a list and serialized it as a JSON array,
where the protocol requires an object. The empty array stays exempt: it is
also an empty map and still emits `{}`.
`ToolChoice` and `ElicitRequest` read their mode with isset(), which is false
for an explicit null, so `{"mode": null}` silently became the default instead
of being rejected. Both use array_key_exists() now, letting the existing type
check refuse null.
* [Client][Server] Advertise the implementation title through both builders
`Implementation::title` could be parsed but never sent: neither
`Client\Builder::setClientInfo()` nor `Server\Builder::setServerInfo()`
accepted one, so every SDK user emitted null.
Both gain a trailing optional `$title`. On the server it sits where the
Implementation constructor already puts it, so existing positional calls keep
their meaning; the client builder forwards it by name, leaving the icons and
websiteUrl slots defaulted.
* [Schema] Serialize every non-null structuredContent
The object-only hydration guard was never that: `!is_array()` admitted
`[1, 2, 3]` and `[]`, which serialize to JSON arrays, while rejecting the
scalars 2026-07-28 permits. The truthiness emission gate was backwards in the
same way — it dropped `[]`, `0`, `false` and `""`, yet emitted lists, strings
and an empty stdClass.
Hydration now accepts any JSON value, and `null` alone means absent, matching
`ToolResultContent` which already carries this field that way. Which values a
given revision permits is a question for version-aware serialization, which
results cannot answer yet.
* [Schema][Server] Make url elicitation reachable
`ElicitRequest::forUrl()` built a request no SDK user could send: the only
public gateway method always constructed form mode from an ElicitationSchema,
and `request()` is private.
`elicitUrl()` joins `elicit()`, and both funnel through one send path that
hydrates the result with the request's own mode. Without that, a url-mode
accept — contentless by design — threw, because ElicitResult requires content
whenever the action is accept. The result carries no discriminator of its own,
so the mode has to come from the request it answers.
`supportsElicitationUrl()` reports whether the client named the mode, reusing
the sub-capability reader the sampling checks already use.
* [Schema] Add CHANGELOG entry for the 2026-07-28 surface
* [Capability][Schema][Server] Carry the widened structuredContent end to end
Review follow-up on the SEP-2106 widening, which stopped at the type.
`ToolReference::extractStructuredContent()` returned `?array`, so a tool
declaring a scalar `outputSchema` had its result dropped and logged as
unsendable. It returns `mixed` now and keeps a scalar — but only from
2026-07-28 on, and only when the tool declared an outputSchema: without one
the value is already carried in `content`, and advertising it twice is not an
improvement.
`CallToolHandler` only warned about list-shaped `structuredContent` on a
self-built `CallToolResult`, so a scalar reached revisions that require an
object unremarked. The check is on the shape now, not on the list case alone.
`ElicitResult` retained a `content` the spec says is absent from url-mode
results, leaving a malformed response indistinguishable from a valid one.
`Tool::jsonSerialize()` emitted the empty root schema as `[]`, which is not a
schema at all. Sub-schemas already had this treatment.
* [Client] Implement setMaxRetries connection retries
* [Client] Reject a negative retry count in Configuration
* [Client] Use a positive init timeout in the retry test
* [Client] Drop redundant docblock note on setMaxRetries
* [Client] Clear the initialized flag on a failed connection
* [Client] Trim comments to the non-obvious ones
* [Client] Cover retries and timeout cleanup with integration tests
The retry fixture counts the processes it was started as, which is what
separates a real retry from a second call into the same server. The timeout
fixture outlives the client's patience and then goes idle, so the next
request runs on a connection the client already gave up on once.
* feat(client): add complete MCP client SDK with STDIO and HTTP transports
Add Client, Builder, ClientProtocol, ClientSession, and transport
implementations for communicating with MCP servers. Supports tools, resources, prompts, and real-time progress/logging notifications.
* refactor(examples): reorganize examples into server/ and client/ folders
* feat: add SamplingRequestHandler for handling server sampling requests
* feat: add setLoggingLevel method to control server logging verbosity
* refactor: make progress token dependent on request ID
* docs: Update server IP in usage instructions and add notes on sampling server requirements.
* feat: add complete() method for completion/complete requests
* refactor: properly parse and type initialize result
* refactor: standardize method names
* fix: revert changes to server related components
* fix: revert changes to server related components
* refactor: Restructure client transports and handlers into dedicated namespaces.
* fix: cs and php-stan errors fixes(partial)
* feat: Refactor request handlers to return `Response` or `Error` objects directly, adding a `SamplingException` and error logging for sampling requests.
* feat: Replace `ClientTransportInterface` with `TransportInterface` and move response result deserialization to client methods.
* refactor: remove redundant timeout check for intialize on transports
The processFiber that executes per tick while fiber is suspended already handles timeouts while waiting
* feat: broaden symfony/http-client dependency to support Symfony 5.4 to 8.0
* Update examples/client/README.md
Co-authored-by: Christopher Hertel <mail@christopher-hertel.de>
* Update examples/client/README.md
Co-authored-by: Christopher Hertel <mail@christopher-hertel.de>
* refactor: remove outgoing message queue from session and simplify transport send method to directly dispatch messages.
* refactor: Replace ClientSession with ClientState for clearer intent on runtime state management
* refactor: rename connectAndInitialize to connect for consistency
* chore: cs fix
* chore: use SamplingCallbackInterface instead of a closure for sampling request handler
---------
Co-authored-by: Christopher Hertel <mail@christopher-hertel.de>
