Every cacheable result went out as ttlMs 0, private — the letter of
SEP-2549 and none of its point, with no way to change it. CachePolicy adds
a default and per-method overrides; a resource can override per read. The
conservative default stands, because public means a shared cache may serve
one caller's answer to another.
The revision has no way for a server to put a request on a response stream,
so a handler that needs input from the user says so in its result instead: a
handler returning InputRequiredResult comes back as
resultType: "input_required" with the asks and an opaque requestState, and
the client retries the same request carrying inputResponses.
RequestContext::getInputContext() is what the handler reads them through.
RequestStateCodec signs and time-bounds the state, so a tampered or expired
one is refused rather than trusted - the state travels through the client,
which is not a place to keep something the server later believes.
The revision puts the method, the subject name and the mirrored arguments in
headers so an intermediary can route and cache without parsing the body. A
header that contradicts the body it travels with therefore has to be
refused, not ignored: StandardHeaderValidator compares each against the
request and answers -32020 on a mismatch.
Set with Builder::setHeaderValidator(); a transport with no header layer is
unaffected.
* [Server][Tests] Serve the modern (SEP-2575) lifecycle
The revision removed the initialize handshake: every request carries its own
_meta - protocol version, client capabilities, client info - and answers
server/discover for what initialize used to return. There is no session to
keep, so there is nothing for the handshake-era dispatcher to do.
Builder::buildStateless() produces StatelessProtocol, and
StatelessHttpTransport serves it over one POST-only endpoint - GET and
DELETE are 405, and no Mcp-Session-Id exists to hand out.
Results go through a per-era wire codec rather than the handlers, so
resultType and the caching hints are stamped for 2026-07-28 and left off the
revisions that do not define them.
Covered by the modern conformance suite (make conformance-draft-server)
against its own baseline; unit coverage arrives with the fixes stacked on
this.
* Apply suggestions from code review
Co-authored-by: Christopher Hertel <mail@christopher-hertel.de>
* Fix critical stateless-lifecycle bugs from review
- Don't leak internal exception messages to clients on uncaught
\Throwable; use a generic message like the handshake-era protocol
and every built-in handler already do.
- Default a missing/invalid request id to null instead of "", and
stop answering notifications and malformed messages as if they
were "method not found" 404s.
- Read the POST body in a loop instead of a single read() call,
which PSR-7 allows to return short.
