* Preserve request id in JSON-RPC error responses instead of fabricating id:""
When the server received input it could not turn into a valid message, the
error response carried a fabricated empty-string id that was never in the
request, breaking JSON-RPC client correlation.
The id default for the error factories was '' and that default reached the
wire unchanged: unrecoverable parse errors emitted id:"", and for invalid-
but-parseable messages MessageFactory discarded the decoded id so it also
fell back to "".
Now unrecoverable parse errors (-32700) return id: null per JSON-RPC 2.0,
and invalid-but-parseable requests (-32600) preserve the original request
id. Error::$id / getId() and the $id parameter of forParseError() /
forInvalidRequest() are widened to string|int|null, and the recoverable id
is threaded through InvalidInputMessageException.
Fixes#333
* Preserve nullable request id consistently across Error factories and fromArray
- Widen the remaining for*() factories (forMethodNotFound, forInvalidParams,
forInternalError, forServerError, forResourceNotFound) to string|int|null
defaulting to null, so no error path can fabricate id:"" again. The only
defaulting call site (ProtocolVersionMiddleware) now emits id:null instead
of id:"" for a pre-parse rejection, which is the spec-correct value.
- Accept a null id in Error::fromArray(): require the id key to be present
(JSON-RPC responses must carry it) but allow its value to be null, so a
spec-compliant id:null error response round-trips and incoming error
responses with id:null are accepted instead of rejected.
- Widen the @phpstan-type ErrorData id to string|int|null to match the ctor,
getId(), and jsonSerialize() shape.
* Document intentional id recovery guard in MessageFactory
* Cover id: 0 and string ids in recoverable-id preservation test
* Fixed client handling of null-id error responses
* [Schema] Omit the id of an error response that never had one
An error response whose id could not be read sent `"id": ""`, which claims
the peer issued a request with an empty-string id - a different statement
from "the id could not be read". JSON-RPC spells the latter as a null id,
and a receiver that cannot read the id is exactly the case the code covers.
[BC Break] Error::$id accepts null and getId() may return it. All the for*()
factories default to null, fromArray() accepts a missing or explicitly-null
id, and the member is omitted from the serialized form when absent.
* Guard null response id in Client/Server Protocol handlers
Also fix Error::jsonSerialize()'s phpdoc: data belongs inside error, not beside it.
* [Client][Docs][Schema][Server] Implement protocol version negotiation
The `initialize` handler never looked at the version the client asked for:
it always answered with the server's configured version (or the SDK default),
so a client offering a revision the server supports could still be told to
speak a different one. The spec requires echoing back a supported request and
only counter-offering when the requested version cannot be honoured.
Turns ProtocolVersion into the registry the other SDKs converged on
(typescript-sdk's protocolEras.ts, python-sdk's mcp_types/version.py):
`latestHandshake()`, `handshakeVersions()`, `modernVersions()` and ordered
comparison through `isAtLeast()`. Comparison goes through declaration order
rather than string collation, so an unrecognized peer string compares
conservatively instead of accidentally sorting above a known revision. The
one throw the enum can produce is the SDK's own LogicException, so a consumer
catching `Mcp\Exception\ExceptionInterface` does not miss it.
Adds 2026-07-28 as a known revision and splits the set into two eras:
handshake (2025-11-25 and earlier, negotiated via `initialize`) and modern
(2026-07-28+, per-request `_meta`). The lists are kept apart so a modern
revision can never leak into an `initialize` exchange, which has no
`initialize` at all. Serving the modern era is follow-up work; this only
teaches the SDK that the revision exists and must not be mis-negotiated.
Deliberately absent is any "newest revision in any era" accessor, which
would hand back the one revision the handshake must never offer.
Server: negotiates and stores the result on the session. A version pinned in
Configuration still pins the handshake to exactly that revision.
Client: validates the counter-offer and fails the handshake instead of
continuing on a revision it cannot speak; records the negotiated version on
the client state, readable through the new Client::getProtocolVersion().
The HTTP middleware now defaults to the handshake versions rather than every
declared case, so it stops accepting a modern version the server cannot yet
serve. When the header is absent it falls back to
ProtocolVersion::DEFAULT_NEGOTIATED_VERSION (2025-03-26), the revision that
introduced both Streamable HTTP and the header itself.
The negotiation behaviour is one provideNegotiationTable() data provider
whose rows are the documented table -- supported revision echoed back,
unknown or malformed counter-offered, modern counter-offered -- so the docs
and the suite cannot drift apart. The supported-revision rows iterate
handshakeVersions() rather than a literal list, so declaring a new handshake
revision extends the table automatically, and the "never answer with a modern
revision" assertion runs on every row.
Documented in server-builder.md (the enum registry, how the server answers a
handshake, what pinning changes), transports.md (the header check) and
client.md (the client's side), all linking the spec's versioning section.
* [Client][Docs][Schema][Server] Warn when the configured protocol version cannot be negotiated
* Log a warning instead of silently falling back when a modern revision is
configured on the client or pinned on the server builder.
* Document that setProtocolVersion() does not restrict the MCP-Protocol-Version
header check, which validates against a fixed set.
* Pin every revision's era in a test, so a new case declared past the modern
boundary fails instead of dropping out of the handshake set.
* Add CHANGELOG entry.
* [Client][Docs][Schema][Server] Rename version fallback constant and trim comments
