diff --git a/.github/workflows/test_core.yml b/.github/workflows/test_core.yml
index 3b1ec340..73896c30 100644
--- a/.github/workflows/test_core.yml
+++ b/.github/workflows/test_core.yml
@@ -52,7 +52,7 @@ jobs:
 
       - name: Run official MCP 2025 client conformance
         run: >
-          npx -y @modelcontextprotocol/conformance@0.2.0-alpha.7 client
+          npx -y @modelcontextprotocol/conformance@0.2.0-alpha.8 client
           --command "dart run test/conformance/mcp_2026_07_28_rc_client.dart"
           --suite all
           --spec-version 2025-11-25
diff --git a/CHANGELOG.md b/CHANGELOG.md
index c60139b4..c41f63b9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,22 +8,22 @@
 
 ### Conformance and interoperability
 
-- Documented that published TypeScript SDK `2.0.0-alpha.3` packages are not yet
-  valid replacements for the `pkg.pr.new` 2026-07-28 RC interop fixture because
-  the alpha.3 client is missing the preview negotiation API used by the fixture.
+- Re-pinned the TypeScript SDK 2026-07-28 RC interop fixture from `pkg.pr.new`
+  previews to published `@modelcontextprotocol/client@2.0.0-beta.1` and
+  `@modelcontextprotocol/server@2.0.0-beta.1` packages after verifying both
+  Dart -> TypeScript and TypeScript -> Dart 2026 draft/RC paths.
 - Updated official conformance gates to
-  `@modelcontextprotocol/conformance@0.2.0-alpha.7`. The 2026-07-28 RC server suite
-  now has no expected failures; the 2026 client suite keeps only the upstream
+  `@modelcontextprotocol/conformance@0.2.0-alpha.8`, adding the new stateless
+  diagnostic probes for missing client capabilities, response-stream shape, and
+  request-scoped logging. The 2026-07-28 RC server suite now has no expected
+  failures; the 2026 client suite keeps only the upstream
   `json-schema-ref-no-deref` fixture gap expected.
-- Added a dedicated CI workflow for the TypeScript SDK 2026-07-28 RC preview
+- Added a dedicated CI workflow for the TypeScript SDK 2026-07-28 RC beta
   interop fixture on relevant PRs, `dev/2026-07-28-rc` pushes, daily schedule,
   and manual dispatch.
 - Added an MCP 2026-07-28 draft/RC spec coverage matrix that maps the opt-in
-  profile to official conformance, local tests, and TypeScript preview interop.
-- Re-pinned the TypeScript SDK 2026-07-28 RC interop fixture to
-  `pkg.pr.new` previews from the merged `v2-2026-07-28` branch head for both
-  client and server packages.
-- Switched the reverse Dart preview client -> TypeScript preview server fixture
+  profile to official conformance, local tests, and TypeScript SDK beta interop.
+- Switched the reverse Dart 2026 client -> TypeScript SDK beta server fixture
   to the TypeScript SDK's 2026 HTTP handler entry, making `server/discover`,
   `tools/list`, and `tools/call` strict interop checks instead of diagnostic
   skips.
diff --git a/README.md b/README.md
index db660c1c..d7d3151a 100644
--- a/README.md
+++ b/README.md
@@ -137,7 +137,7 @@ for opt-in behavior, fallback rules, and draft-only APIs.
 
 - 🧪 **[SDK Interoperability Matrix](https://github.com/leehack/mcp_dart/blob/dev/2026-07-28-rc/doc/interoperability.md)** - Verified Dart/TypeScript and documented cross-SDK scenarios
 - ✅ **[MCP 2025-11-25 Spec Coverage Matrix](https://github.com/leehack/mcp_dart/blob/dev/2026-07-28-rc/doc/spec-coverage-2025-11-25.md)** - Auditable coverage map with CLI conformance cases and known gaps
-- 🧪 **[MCP 2026-07-28 Draft/RC Spec Coverage Matrix](https://github.com/leehack/mcp_dart/blob/dev/2026-07-28-rc/doc/spec-coverage-2026-07-28-rc.md)** - Opt-in draft/RC coverage map across official conformance and TypeScript preview interop
+- 🧪 **[MCP 2026-07-28 Draft/RC Spec Coverage Matrix](https://github.com/leehack/mcp_dart/blob/dev/2026-07-28-rc/doc/spec-coverage-2026-07-28-rc.md)** - Opt-in draft/RC coverage map across official conformance and TypeScript SDK beta interop
 - 🧭 **[MCP 2026-07-28 Draft/RC Transition Guide](https://github.com/leehack/mcp_dart/blob/dev/2026-07-28-rc/doc/mcp-2026-07-28-rc.md)** - Opt-in profile, fallback behavior, and draft-only APIs
 - 🔒 **[Transport Security Recipes](https://github.com/leehack/mcp_dart/blob/dev/2026-07-28-rc/doc/transports.md#dns-rebinding-protection)** - Host/Origin allowlists, OAuth layering, and compatibility-toggle trade-offs
 - 📱 **[Flutter Recipes](https://github.com/leehack/mcp_dart/blob/dev/2026-07-28-rc/doc/flutter-recipes.md)** - Flutter Web, mobile, and desktop host/client guidance
diff --git a/doc/interoperability.md b/doc/interoperability.md
index 0ebefd48..35ef7317 100644
--- a/doc/interoperability.md
+++ b/doc/interoperability.md
@@ -23,8 +23,8 @@ For MCP 2026-07-28 draft/RC coverage, see the
 | Dart client -> TypeScript SDK server | Streamable HTTP | `2025-11-25` | [`test/interop/dart_client_with_ts_server_test.dart`](../test/interop/dart_client_with_ts_server_test.dart), [`test/interop/ts/`](../test/interop/ts/) | Verified | Covers tool calls and stale preconfigured session-id recovery. |
 | TypeScript SDK client -> Dart server | stdio | `2025-11-25` | [`test/interop/ts_client_with_dart_server_test.dart`](../test/interop/ts_client_with_dart_server_test.dart), [`test/interop/test_dart_server.dart`](../test/interop/test_dart_server.dart) | Verified | Runs the compiled TypeScript client fixture against a Dart server process and checks that an official TS client can list tools immediately after the lifecycle handshake. |
 | TypeScript SDK client -> Dart server | Streamable HTTP | `2025-11-25` | [`test/interop/ts_client_with_dart_server_test.dart`](../test/interop/ts_client_with_dart_server_test.dart), [`test/interop/test_dart_server.dart`](../test/interop/test_dart_server.dart) | Verified | Includes official TS Streamable HTTP client lifecycle coverage, pre-`initialized` operation rejection, GET SSE streams, and `Last-Event-ID` replay behavior. |
-| TypeScript SDK preview client -> Dart server | Streamable HTTP | `2026-07-28` draft/RC | [`test/interop/ts_2026_07_28_rc/`](../test/interop/ts_2026_07_28_rc/), [`tool/testing/run_ts_2026_07_28_rc_interop.dart`](../tool/testing/run_ts_2026_07_28_rc_interop.dart), [`interop_2026_07_28.yml`](../.github/workflows/interop_2026_07_28.yml) | Automated preview check | Uses pinned `pkg.pr.new` previews from the TypeScript SDK `v2-2026-07-28` branch head. Covers modern negotiation, cache metadata, `tools/list`, `tools/call`, `x-mcp-header` mirroring, raw header and unsupported-version rejection, removed core RPC rejection, progress notifications, `subscriptions/listen`, and HTTP SSE cancellation against the Dart 2026-07-28 RC conformance server. |
-| Dart preview client -> TypeScript SDK preview server | Streamable HTTP | `2026-07-28` draft/RC | [`test/interop/ts_2026_07_28_rc/src/server.mjs`](../test/interop/ts_2026_07_28_rc/src/server.mjs), [`tool/testing/run_ts_2026_07_28_rc_interop.dart`](../tool/testing/run_ts_2026_07_28_rc_interop.dart), [`interop_2026_07_28.yml`](../.github/workflows/interop_2026_07_28.yml) | Automated preview check | Uses the pinned TypeScript SDK server preview through its `createMcpHandler` entry and covers `server/discover` negotiation, `tools/list`, and `tools/call`. |
+| TypeScript SDK beta client -> Dart server | Streamable HTTP | `2026-07-28` draft/RC | [`test/interop/ts_2026_07_28_rc/`](../test/interop/ts_2026_07_28_rc/), [`tool/testing/run_ts_2026_07_28_rc_interop.dart`](../tool/testing/run_ts_2026_07_28_rc_interop.dart), [`interop_2026_07_28.yml`](../.github/workflows/interop_2026_07_28.yml) | Automated 2026 check | Uses published `@modelcontextprotocol/client@2.0.0-beta.1` and `@modelcontextprotocol/server@2.0.0-beta.1` packages. Covers modern negotiation, cache metadata, `tools/list`, `tools/call`, `x-mcp-header` mirroring, raw header and unsupported-version rejection, removed core RPC rejection, progress notifications, `subscriptions/listen`, and HTTP SSE cancellation against the Dart 2026-07-28 RC conformance server. |
+| Dart 2026 client -> TypeScript SDK beta server | Streamable HTTP | `2026-07-28` draft/RC | [`test/interop/ts_2026_07_28_rc/src/server.mjs`](../test/interop/ts_2026_07_28_rc/src/server.mjs), [`tool/testing/run_ts_2026_07_28_rc_interop.dart`](../tool/testing/run_ts_2026_07_28_rc_interop.dart), [`interop_2026_07_28.yml`](../.github/workflows/interop_2026_07_28.yml) | Automated 2026 check | Uses the published TypeScript SDK beta server through its `createMcpHandler` entry and covers `server/discover` negotiation, `tools/list`, and `tools/call`. |
 | Dart client -> Python MCP server | stdio | Server-dependent | [`doc/transports.md`](transports.md#connect-to-python-server) | Documented recipe | The transport can spawn Python servers over stdio, but this repo does not yet include an automated Python SDK fixture. |
 | Flutter/Web client -> Dart server | Streamable HTTP | `2026-07-28` draft/RC preview with stable fallback | [`example/flutter_http_client/`](../example/flutter_http_client/), [`doc/flutter-recipes.md`](flutter-recipes.md) | Documented recipe | Flutter Web cannot spawn stdio servers; use Streamable HTTP or another browser-safe transport. The example opts into preview negotiation while retaining stable fallback. |
 | MCP Apps host/client metadata | stdio or Streamable HTTP | `2026-07-28` draft/RC preview plus `io.modelcontextprotocol/ui` extension | [`doc/mcp-apps.md`](mcp-apps.md), [`example/mcp_apps_helpers_server.dart`](../example/mcp_apps_helpers_server.dart), [`test/types/mcp_ui_test.dart`](../test/types/mcp_ui_test.dart), [`test/server/mcp_ui_test.dart`](../test/server/mcp_ui_test.dart) | Verified | Verified coverage is limited to SDK metadata helpers, serialization, and checked-in examples; host rendering behavior varies by host, so verify UI metadata against your target host. |
@@ -46,8 +46,8 @@ dart test --tags interop
 
 If the compiled fixtures are missing, local test runs skip the interop groups; CI should fail when required fixtures are unavailable.
 
-The TypeScript 2026-07-28 RC fixture uses unreleased `pkg.pr.new` previews from
-the TypeScript SDK `v2-2026-07-28` branch:
+The TypeScript 2026-07-28 RC fixture uses the published TypeScript SDK beta
+packages:
 
 ```bash
 # From repository root
@@ -57,17 +57,15 @@ cd ../../..
 dart run tool/testing/run_ts_2026_07_28_rc_interop.dart
 ```
 
-This starts the Dart 2026-07-28 RC conformance server, runs the pinned TypeScript SDK
-preview client against it, then runs the reverse Dart preview client smoke check
-against the TypeScript preview server.
+This starts the Dart 2026-07-28 RC conformance server, runs the pinned TypeScript
+SDK beta client against it, then runs the reverse Dart 2026 client smoke check
+against the TypeScript SDK beta server.
 
-Published `@modelcontextprotocol/client@2.0.0-alpha.3` and
-`@modelcontextprotocol/server@2.0.0-alpha.3` packages are not yet suitable
-replacements for this fixture: the published alpha.3 client does not expose the
-preview `versionNegotiation` / `getProtocolEra` APIs used here, and a direct
-`supportedProtocolVersions: ["2026-07-28"]` repin fails the handshake. Keep the
-`pkg.pr.new` pin until a published TypeScript SDK package exposes the 2026 draft
-path and this interop runner passes against it.
+The fixture previously depended on `pkg.pr.new` artifacts because published
+`2.0.0-alpha.3` packages did not expose the preview negotiation API used here.
+`@modelcontextprotocol/client@2.0.0-beta.1` and
+`@modelcontextprotocol/server@2.0.0-beta.1` expose the required modern path and
+the interop runner passes against them.
 
 CI also runs this fixture in the dedicated
 `Run MCP 2026-07-28 TypeScript Interop` workflow for relevant PRs,
@@ -96,12 +94,7 @@ When adding a new interoperability claim:
 ## Known gaps worth tracking
 
 - Automated Python SDK fixture coverage.
-- Re-pin the TypeScript 2026-07-28 RC interop fixture to a published upstream
-  alpha package once that package exposes the 2026 draft path. The published
-  `@modelcontextprotocol/client/server@2.0.0-alpha.3` packages are not enough
-  because the client is missing the preview negotiation API used by this
-  fixture.
-- Broader reverse-path TypeScript preview server coverage beyond discovery,
+- Broader reverse-path TypeScript SDK beta server coverage beyond discovery,
   `tools/list`, and `tools/call`.
 - Host-specific MCP Apps rendering compatibility notes.
 - More OAuth-protected remote server scenarios beyond the checked-in examples.
diff --git a/doc/mcp-2026-07-28-rc.md b/doc/mcp-2026-07-28-rc.md
index c6ad40ed..5431d2a7 100644
--- a/doc/mcp-2026-07-28-rc.md
+++ b/doc/mcp-2026-07-28-rc.md
@@ -131,7 +131,7 @@ Before creating follow-up dev tags from `dev/2026-07-28-rc`, run:
 ```sh
 dart analyze
 dart run test/conformance/run_2025_server_conformance.dart
-npx -y @modelcontextprotocol/conformance@0.2.0-alpha.7 client \
+npx -y @modelcontextprotocol/conformance@0.2.0-alpha.8 client \
   --command "dart run test/conformance/mcp_2026_07_28_rc_client.dart" \
   --suite all \
   --spec-version 2025-11-25
@@ -147,21 +147,20 @@ dart run tool/validate_cli_publish.dart
 ```
 
 The `run_2026_07_28_rc_server_conformance.dart` gate runs the full
-`@modelcontextprotocol/conformance@0.2.0-alpha.7` server scenario list for
+`@modelcontextprotocol/conformance@0.2.0-alpha.8` server scenario list for
 `--spec-version 2026-07-28`, including the stable-style tool, resource, prompt,
 completion, and JSON Schema scenarios that the alpha package tags for the RC.
 
-For cross-SDK smoke coverage against the TypeScript SDK 2026 preview packages,
+For cross-SDK smoke coverage against the TypeScript SDK 2026 beta packages,
 run the fixture documented in
 [`doc/interoperability.md`](interoperability.md#running-interop-checks-locally).
 CI also runs it in the dedicated `Run MCP 2026-07-28 TypeScript Interop`
 workflow on relevant PRs, `dev/2026-07-28-rc` pushes, a daily schedule, and
 manual dispatch. Keep it pinned to the draft behavior rather than TypeScript
-preview behavior alone; re-pin from `pkg.pr.new` to a published TypeScript SDK
-alpha only when the published package advertises `2026-07-28` support. The
-published `@modelcontextprotocol/client/server@2.0.0-alpha.3` packages are
-missing the preview negotiation API used by this fixture, so they are not a
-replacement for the current preview pin.
+preview behavior alone. The fixture is currently pinned to published
+`@modelcontextprotocol/client@2.0.0-beta.1` and
+`@modelcontextprotocol/server@2.0.0-beta.1`, which expose the 2026 negotiation
+path and pass the checked-in interop runner.
 
 For dev packages, keep package documentation links pointed at
 `dev/2026-07-28-rc` until the draft work is ready to merge back to `main`.
diff --git a/doc/spec-coverage-2026-07-28-rc.md b/doc/spec-coverage-2026-07-28-rc.md
index 95c3d29f..0da5f300 100644
--- a/doc/spec-coverage-2026-07-28-rc.md
+++ b/doc/spec-coverage-2026-07-28-rc.md
@@ -14,7 +14,7 @@ Run the official conformance gates from the repository root:
 
 ```bash
 dart run test/conformance/run_2025_server_conformance.dart
-npx -y @modelcontextprotocol/conformance@0.2.0-alpha.7 client \
+npx -y @modelcontextprotocol/conformance@0.2.0-alpha.8 client \
   --command "dart run test/conformance/mcp_2026_07_28_rc_client.dart" \
   --suite all \
   --spec-version 2025-11-25
@@ -22,7 +22,7 @@ dart run test/conformance/run_2026_07_28_rc_server_conformance.dart
 dart run test/conformance/run_2026_07_28_rc_client_conformance.dart
 ```
 
-Run the TypeScript preview interop gate from the repository root:
+Run the TypeScript SDK beta interop gate from the repository root:
 
 ```bash
 cd test/interop/ts_2026_07_28_rc
@@ -32,7 +32,7 @@ dart run tool/testing/run_ts_2026_07_28_rc_interop.dart
 ```
 
 CI runs the official conformance gates in the core workflow. The
-`Run MCP 2026-07-28 TypeScript Interop` workflow runs the TypeScript preview
+`Run MCP 2026-07-28 TypeScript Interop` workflow runs the TypeScript SDK beta
 interop fixture on relevant PRs, `dev/2026-07-28-rc` pushes, a daily schedule,
 and manual dispatch.
 
@@ -40,29 +40,23 @@ and manual dispatch.
 
 | Spec area | Draft source | Requirement tracked here | Local coverage | Cross-SDK coverage | Official conformance | Status |
 | --- | --- | --- | --- | --- | --- | --- |
-| Opt-in profile and stable default | [Versioning and compatibility](https://modelcontextprotocol.io/specification/draft/basic/versioning) | Stable MCP `2025-11-25` remains default, while 2026 behavior is selected explicitly with preview or require profiles. | [`test/mcp_2026_07_28_test.dart`](../test/mcp_2026_07_28_test.dart), [`doc/mcp-2026-07-28-rc.md`](mcp-2026-07-28-rc.md) | TypeScript preview interop uses explicit 2026 clients and servers only. | 2025 and 2026 conformance both run in CI. | Verified |
-| Version negotiation and discovery | [Discovery](https://modelcontextprotocol.io/specification/draft/server/discover), [Versioning](https://modelcontextprotocol.io/specification/draft/basic/versioning) | Servers implement `server/discover`, advertise supported versions and capabilities, reject unsupported versions with draft error data, and clients retry or fall back according to transport-era rules. | [`test/mcp_2026_07_28_test.dart`](../test/mcp_2026_07_28_test.dart), [`test/conformance/mcp_2026_07_28_rc_server.dart`](../test/conformance/mcp_2026_07_28_rc_server.dart), [`test/conformance/mcp_2026_07_28_rc_client.dart`](../test/conformance/mcp_2026_07_28_rc_client.dart) | [`tool/testing/run_ts_2026_07_28_rc_interop.dart`](../tool/testing/run_ts_2026_07_28_rc_interop.dart) validates TypeScript preview client -> Dart server and Dart preview client -> TypeScript preview server discovery. | `protocol-version`, `server/discover`, and client negotiation scenarios in alpha.7. | Verified |
-| Stateless request metadata | [Overview](https://modelcontextprotocol.io/specification/draft/basic), [Versioning](https://modelcontextprotocol.io/specification/draft/basic/versioning) | Every 2026 request carries protocol version, client identity, and client capabilities in `_meta`; servers do not infer protocol state from a prior request. | [`test/mcp_2026_07_28_test.dart`](../test/mcp_2026_07_28_test.dart), [`test/server/streamable_https_test.dart`](../test/server/streamable_https_test.dart) | TypeScript preview client fixture exercises normal request paths with 2026 metadata. | `stateless` and `stateless-http` scenarios in alpha.7. | Verified |
-| Streamable HTTP routing headers | [Key changes](https://modelcontextprotocol.io/specification/draft/changelog), [Transports](https://modelcontextprotocol.io/specification/draft/basic/transports) | 2026 HTTP POST requests include required protocol, method, name, and parameter-routing headers; mismatches reject with draft header errors. | [`test/mcp_2026_07_28_test.dart`](../test/mcp_2026_07_28_test.dart), [`test/server/streamable_https_test.dart`](../test/server/streamable_https_test.dart) | TypeScript preview client fixture validates `x-mcp-header` mirroring and raw header rejection against the Dart server. | `stateless-http.requires-routing-headers`, `stateless-http.validates-parameter-headers`, and related alpha.7 cases. | Verified |
-| Removed session and resumability behavior | [Key changes](https://modelcontextprotocol.io/specification/draft/changelog) | 2026 Streamable HTTP omits protocol-level sessions, rejects removed GET/DELETE behaviors, rejects JSON-RPC batches, and treats closed SSE response streams as request cancellation without legacy redelivery. | [`test/mcp_2026_07_28_test.dart`](../test/mcp_2026_07_28_test.dart), [`test/server/streamable_mcp_server_test.dart`](../test/server/streamable_mcp_server_test.dart) | TypeScript preview fixture closes the Dart SSE response stream and verifies no legacy `notifications/cancelled` side effect is required. | `stateless-http.rejects-non-post-methods`, `stateless-http.rejects-batch-payloads`, and related alpha.7 cases. | Verified |
-| Cacheable results and deterministic lists | [Key changes](https://modelcontextprotocol.io/specification/draft/changelog), [Discovery](https://modelcontextprotocol.io/specification/draft/server/discover) | `server/discover`, list, and read responses include `resultType`, `ttlMs`, and `cacheScope`; stateless `tools/list` is deterministic and omits stable-only tool execution metadata. | [`test/mcp_2026_07_28_test.dart`](../test/mcp_2026_07_28_test.dart), [`test/conformance/mcp_2026_07_28_rc_server.dart`](../test/conformance/mcp_2026_07_28_rc_server.dart) | TypeScript preview client fixture checks discovery cache metadata and `tools/list` cache metadata. | Cacheable-result and tools-list scenarios in alpha.7. | Verified |
-| Tools and JSON Schema 2020-12 | [Tools](https://modelcontextprotocol.io/specification/draft/server/tools), [Overview JSON Schema usage](https://modelcontextprotocol.io/specification/draft/basic) | Tool schemas preserve JSON Schema 2020-12 constructs, including nested boolean schemas; stable root-object compatibility remains intact for 2025 behavior. | [`test/tool_schema_test.dart`](../test/tool_schema_test.dart), [`test/mcp_2026_07_28_test.dart`](../test/mcp_2026_07_28_test.dart), [`test/conformance/mcp_2026_07_28_rc_server.dart`](../test/conformance/mcp_2026_07_28_rc_server.dart) | TypeScript preview fixture validates `tools/list` and `tools/call`; deeper schema semantics are covered by local and conformance tests. | 2026 server suite is green; 2026 client suite keeps the upstream `json-schema-ref-no-deref` fixture gap expected. | Verified with one upstream client fixture gap |
-| MRTR and elicitation | [Message patterns](https://modelcontextprotocol.io/specification/draft/basic) | 2026 `input_required` results are emitted only for supported requests and require advertised client capabilities. | [`test/mcp_2026_07_28_test.dart`](../test/mcp_2026_07_28_test.dart), [`test/elicitation_test.dart`](../test/elicitation_test.dart) | TypeScript preview client fixture completes a 2026 `input_required` retry flow against the Dart server. | `mrtr` scenarios in alpha.7. | Verified |
-| Subscriptions | [Subscriptions](https://modelcontextprotocol.io/specification/draft/basic/utilities/subscriptions), [Schema reference](https://modelcontextprotocol.io/specification/draft/schema#subscriptionslistenresult) | `subscriptions/listen` acknowledges before list-change notifications, filters unsupported notification types, correlates notifications through `io.modelcontextprotocol/subscriptionId`, and returns `SubscriptionsListenResult` with the same required subscription id metadata on graceful close. | [`test/mcp_2026_07_28_test.dart`](../test/mcp_2026_07_28_test.dart), [`test/conformance/mcp_2026_07_28_rc_server.dart`](../test/conformance/mcp_2026_07_28_rc_server.dart) | TypeScript preview fixture validates `subscriptions/listen` acknowledgment and list-change notification correlation against the Dart server. | Subscription scenarios in alpha.7. | Verified |
-| Request-scoped logging and removed core RPCs | [Logging](https://modelcontextprotocol.io/specification/draft/server/utilities/logging), [Key changes](https://modelcontextprotocol.io/specification/draft/changelog) | 2026 stateless requests use request-scoped logging metadata, and removed stable-era core RPCs/notifications are rejected in the 2026 profile. | [`test/mcp_2026_07_28_test.dart`](../test/mcp_2026_07_28_test.dart), [`test/server/server_advanced_test.dart`](../test/server/server_advanced_test.dart) | TypeScript preview fixture validates raw removed-RPC rejection against the Dart server. | Removed-RPC and logging scenarios in alpha.7. | Verified |
+| Opt-in profile and stable default | [Versioning and compatibility](https://modelcontextprotocol.io/specification/draft/basic/versioning) | Stable MCP `2025-11-25` remains default, while 2026 behavior is selected explicitly with preview or require profiles. | [`test/mcp_2026_07_28_test.dart`](../test/mcp_2026_07_28_test.dart), [`doc/mcp-2026-07-28-rc.md`](mcp-2026-07-28-rc.md) | TypeScript SDK beta interop uses explicit 2026 clients and servers only. | 2025 and 2026 conformance both run in CI. | Verified |
+| Version negotiation and discovery | [Discovery](https://modelcontextprotocol.io/specification/draft/server/discover), [Versioning](https://modelcontextprotocol.io/specification/draft/basic/versioning) | Servers implement `server/discover`, advertise supported versions and capabilities, reject unsupported versions with draft error data, and clients retry or fall back according to transport-era rules. | [`test/mcp_2026_07_28_test.dart`](../test/mcp_2026_07_28_test.dart), [`test/conformance/mcp_2026_07_28_rc_server.dart`](../test/conformance/mcp_2026_07_28_rc_server.dart), [`test/conformance/mcp_2026_07_28_rc_client.dart`](../test/conformance/mcp_2026_07_28_rc_client.dart) | [`tool/testing/run_ts_2026_07_28_rc_interop.dart`](../tool/testing/run_ts_2026_07_28_rc_interop.dart) validates TypeScript SDK beta client -> Dart server and Dart 2026 client -> TypeScript SDK beta server discovery. | `protocol-version`, `server/discover`, and client negotiation scenarios in alpha.8. | Verified |
+| Stateless request metadata | [Overview](https://modelcontextprotocol.io/specification/draft/basic), [Versioning](https://modelcontextprotocol.io/specification/draft/basic/versioning) | Every 2026 request carries protocol version, client identity, and client capabilities in `_meta`; servers do not infer protocol state from a prior request. | [`test/mcp_2026_07_28_test.dart`](../test/mcp_2026_07_28_test.dart), [`test/server/streamable_https_test.dart`](../test/server/streamable_https_test.dart) | TypeScript SDK beta client fixture exercises normal request paths with 2026 metadata. | `stateless` and `stateless-http` scenarios in alpha.8. | Verified |
+| Streamable HTTP routing headers | [Key changes](https://modelcontextprotocol.io/specification/draft/changelog), [Transports](https://modelcontextprotocol.io/specification/draft/basic/transports) | 2026 HTTP POST requests include required protocol, method, name, and parameter-routing headers; mismatches reject with draft header errors. | [`test/mcp_2026_07_28_test.dart`](../test/mcp_2026_07_28_test.dart), [`test/server/streamable_https_test.dart`](../test/server/streamable_https_test.dart) | TypeScript SDK beta client fixture validates `x-mcp-header` mirroring and raw header rejection against the Dart server. | `stateless-http.requires-routing-headers`, `stateless-http.validates-parameter-headers`, and related alpha.8 cases. | Verified |
+| Removed session and resumability behavior | [Key changes](https://modelcontextprotocol.io/specification/draft/changelog) | 2026 Streamable HTTP omits protocol-level sessions, rejects removed GET/DELETE behaviors, rejects JSON-RPC batches, and treats closed SSE response streams as request cancellation without legacy redelivery. | [`test/mcp_2026_07_28_test.dart`](../test/mcp_2026_07_28_test.dart), [`test/server/streamable_mcp_server_test.dart`](../test/server/streamable_mcp_server_test.dart) | TypeScript SDK beta fixture closes the Dart SSE response stream and verifies no legacy `notifications/cancelled` side effect is required. | `stateless-http.rejects-non-post-methods`, `stateless-http.rejects-batch-payloads`, and related alpha.8 cases. | Verified |
+| Cacheable results and deterministic lists | [Key changes](https://modelcontextprotocol.io/specification/draft/changelog), [Discovery](https://modelcontextprotocol.io/specification/draft/server/discover) | `server/discover`, list, and read responses include `resultType`, `ttlMs`, and `cacheScope`; stateless `tools/list` is deterministic and omits stable-only tool execution metadata. | [`test/mcp_2026_07_28_test.dart`](../test/mcp_2026_07_28_test.dart), [`test/conformance/mcp_2026_07_28_rc_server.dart`](../test/conformance/mcp_2026_07_28_rc_server.dart) | TypeScript SDK beta client fixture checks discovery cache metadata and `tools/list` cache metadata. | Cacheable-result and tools-list scenarios in alpha.8. | Verified |
+| Tools and JSON Schema 2020-12 | [Tools](https://modelcontextprotocol.io/specification/draft/server/tools), [Overview JSON Schema usage](https://modelcontextprotocol.io/specification/draft/basic) | Tool schemas preserve JSON Schema 2020-12 constructs, including nested boolean schemas; stable root-object compatibility remains intact for 2025 behavior. | [`test/tool_schema_test.dart`](../test/tool_schema_test.dart), [`test/mcp_2026_07_28_test.dart`](../test/mcp_2026_07_28_test.dart), [`test/conformance/mcp_2026_07_28_rc_server.dart`](../test/conformance/mcp_2026_07_28_rc_server.dart) | TypeScript SDK beta fixture validates `tools/list` and `tools/call`; deeper schema semantics are covered by local and conformance tests. | 2026 server suite is green; 2026 client suite keeps the upstream `json-schema-ref-no-deref` fixture gap expected. | Verified with one upstream client fixture gap |
+| MRTR and elicitation | [Message patterns](https://modelcontextprotocol.io/specification/draft/basic) | 2026 `input_required` results are emitted only for supported requests and require advertised client capabilities. | [`test/mcp_2026_07_28_test.dart`](../test/mcp_2026_07_28_test.dart), [`test/elicitation_test.dart`](../test/elicitation_test.dart) | TypeScript SDK beta client fixture completes a 2026 `input_required` retry flow against the Dart server. | `mrtr` scenarios in alpha.8. | Verified |
+| Subscriptions | [Subscriptions](https://modelcontextprotocol.io/specification/draft/basic/utilities/subscriptions), [Schema reference](https://modelcontextprotocol.io/specification/draft/schema#subscriptionslistenresult) | `subscriptions/listen` acknowledges before list-change notifications, filters unsupported notification types, correlates notifications through `io.modelcontextprotocol/subscriptionId`, and returns `SubscriptionsListenResult` with the same required subscription id metadata on graceful close. | [`test/mcp_2026_07_28_test.dart`](../test/mcp_2026_07_28_test.dart), [`test/conformance/mcp_2026_07_28_rc_server.dart`](../test/conformance/mcp_2026_07_28_rc_server.dart) | TypeScript SDK beta fixture validates `subscriptions/listen` acknowledgment and list-change notification correlation against the Dart server. | Subscription scenarios in alpha.8. | Verified |
+| Request-scoped logging and removed core RPCs | [Logging](https://modelcontextprotocol.io/specification/draft/server/utilities/logging), [Key changes](https://modelcontextprotocol.io/specification/draft/changelog) | 2026 stateless requests use request-scoped logging metadata, and removed stable-era core RPCs/notifications are rejected in the 2026 profile. | [`test/mcp_2026_07_28_test.dart`](../test/mcp_2026_07_28_test.dart), [`test/server/server_advanced_test.dart`](../test/server/server_advanced_test.dart) | TypeScript SDK beta fixture validates raw removed-RPC rejection against the Dart server. | Removed-RPC and logging scenarios in alpha.8. | Verified |
 | Draft-only public APIs | [Schema reference](https://modelcontextprotocol.io/specification/draft/schema) | APIs that are useful only for 2026, such as non-object structured tool output and 2026 protocol profiles, are documented as draft/RC APIs and do not change stable defaults. | [`doc/mcp-2026-07-28-rc.md`](mcp-2026-07-28-rc.md), public dartdoc on protocol profiles and draft-only helpers. | Not cross-SDK specific. | Covered indirectly by 2026 conformance and local parser/serializer tests. | Verified |
 
 ## Known Gaps
 
 - The official conformance package is still alpha. The 2026 client suite keeps
-  `json-schema-ref-no-deref` expected-failed because the alpha.7 mock server for
+  `json-schema-ref-no-deref` expected-failed because the alpha.8 mock server for
   that scenario still behaves like a stable-only server.
-- The TypeScript 2026-07-28 fixture depends on `pkg.pr.new` preview artifacts
-  from the TypeScript SDK branch. Keep the CI workflow, but re-pin it to a
-  published alpha package once upstream provides one that advertises the 2026
-  draft path. The published `@modelcontextprotocol/client/server@2.0.0-alpha.3`
-  packages are missing the preview negotiation API used by this fixture, so
-  they are not a valid replacement for the current preview pin.
-- The reverse Dart preview client -> TypeScript preview server path currently
+- The reverse Dart 2026 client -> TypeScript SDK beta server path currently
   covers discovery, `tools/list`, and `tools/call`. Broader reverse-path
-  coverage should follow as the TypeScript preview server surface stabilizes.
+  coverage should follow as the TypeScript SDK beta server surface stabilizes.
diff --git a/lib/src/server/mcp_server.dart b/lib/src/server/mcp_server.dart
index 9447e376..5e5ebd89 100644
--- a/lib/src/server/mcp_server.dart
+++ b/lib/src/server/mcp_server.dart
@@ -15,6 +15,9 @@ import 'tasks.dart';
 
 final _logger = Logger("mcp_dart.server.mcp");
 
+const _requiredClientCapabilitiesMetaKey =
+    'io.modelcontextprotocol/requiredClientCapabilities';
+
 /// Callback capable of providing completions for a partial value.
 typedef CompleteCallback = FutureOr<List<String>> Function(String value);
 
@@ -1083,7 +1086,18 @@ class McpServer {
   /// Connects the server to a communication [transport].
   Future<void> connect(Transport transport) async {
     _syncToolParameterHeaderMappings(transport);
-    return await server.connect(transport);
+    await server.connect(transport);
+    if (transport is IncomingRequestValidationAwareTransport) {
+      final validationAwareTransport =
+          transport as IncomingRequestValidationAwareTransport;
+      validationAwareTransport.setIncomingRequestValidator((request) {
+        final protocolError = server.validateIncomingRequest(request);
+        if (protocolError != null) {
+          return protocolError;
+        }
+        return _validateToolClientCapabilities(request);
+      });
+    }
   }
 
   /// Closes the server connection.
@@ -1094,6 +1108,77 @@ class McpServer {
   /// Checks if the server is connected to a transport.
   bool get isConnected => server.transport != null;
 
+  McpError? _validateToolClientCapabilities(JsonRpcRequest request) {
+    if (request is! JsonRpcCallToolRequest ||
+        !_isDraft2026Request(request.meta?[McpMetaKey.protocolVersion])) {
+      return null;
+    }
+
+    final tool = _registeredTools[request.callParams.name];
+    if (tool == null) {
+      return null;
+    }
+
+    final requiredCapabilities = _requiredClientCapabilities(tool);
+    if (requiredCapabilities.isEmpty) {
+      return null;
+    }
+
+    final clientCapabilitiesValue =
+        request.meta?[McpMetaKey.clientCapabilities];
+    if (clientCapabilitiesValue is! Map) {
+      return McpError(
+        ErrorCode.invalidParams.value,
+        'Missing required request metadata: ${McpMetaKey.clientCapabilities}',
+      );
+    }
+
+    final clientCapabilities = ClientCapabilities.fromJson(
+      clientCapabilitiesValue.cast<String, dynamic>(),
+    );
+    final missingCapabilities = requiredCapabilities
+        .where(
+          (capability) => !_hasClientCapability(clientCapabilities, capability),
+        )
+        .toList(growable: false);
+    if (missingCapabilities.isEmpty) {
+      return null;
+    }
+
+    return McpError(
+      ErrorCode.missingRequiredClientCapability.value,
+      'Missing required client capability',
+      {'requiredCapabilities': missingCapabilities},
+    );
+  }
+
+  List<String> _requiredClientCapabilities(_RegisteredToolImpl tool) {
+    final value = tool.meta?[_requiredClientCapabilitiesMetaKey];
+    if (value is String) {
+      return [value];
+    }
+    if (value is Iterable) {
+      return value.whereType<String>().toList(growable: false);
+    }
+    return const [];
+  }
+
+  bool _hasClientCapability(
+    ClientCapabilities capabilities,
+    String capability,
+  ) {
+    return switch (capability) {
+      'sampling' => capabilities.sampling != null,
+      'roots' => capabilities.roots != null,
+      'elicitation' => capabilities.elicitation != null,
+      'tasks' => capabilities.tasks != null,
+      _ => capabilities.additionalCapabilities?.containsKey(capability) ??
+          capabilities.experimental?.containsKey(capability) ??
+          capabilities.extensions?.containsKey(capability) ??
+          false,
+    };
+  }
+
   /// Sends a logging message to the client, if connected.
   ///
   /// For stateless MCP requests, pass [requestMeta] from
diff --git a/test/conformance/2026_07_28_rc_client_expected_failures.txt b/test/conformance/2026_07_28_rc_client_expected_failures.txt
index fd91ef9e..2cbf84be 100644
--- a/test/conformance/2026_07_28_rc_client_expected_failures.txt
+++ b/test/conformance/2026_07_28_rc_client_expected_failures.txt
@@ -1,10 +1,10 @@
-# Expected failures for @modelcontextprotocol/conformance@0.2.0-alpha.7
+# Expected failures for @modelcontextprotocol/conformance@0.2.0-alpha.8
 # against the 2026-07-28 RC/DRAFT client suite.
 #
 # Keep this list scenario-based so the baseline is easy to review. When a
 # scenario turns green, remove it from this file in the same PR as the fix.
 #
-# Upstream alpha.7 fixture gap: this scenario's mock server still rejects
+# Upstream alpha.8 fixture gap: this scenario's mock server still rejects
 # 2026-07-28 with HTTP 400 and advertises only stable protocol versions.
 # Keep it expected-fail until the conformance fixture is draft-capable.
 json-schema-ref-no-deref
diff --git a/test/conformance/2026_07_28_rc_expected_failures.txt b/test/conformance/2026_07_28_rc_expected_failures.txt
index 20a0c852..21abbea0 100644
--- a/test/conformance/2026_07_28_rc_expected_failures.txt
+++ b/test/conformance/2026_07_28_rc_expected_failures.txt
@@ -1,6 +1,8 @@
-# Expected failures for @modelcontextprotocol/conformance@0.2.0-alpha.7
+# Expected failures for @modelcontextprotocol/conformance@0.2.0-alpha.8
 # against the full 2026-07-28 RC/DRAFT server suite.
 #
+# The alpha.8 server suite has no expected failures against the Dart fixture.
+#
 # Keep this list scenario-based so the baseline is easy to review. When a
 # scenario turns green, remove it from this file in the same PR as the fix.
 #
diff --git a/test/conformance/README.md b/test/conformance/README.md
index 2f494251..e7a5c6b7 100644
--- a/test/conformance/README.md
+++ b/test/conformance/README.md
@@ -26,14 +26,14 @@ dart run test/conformance/run_2025_server_conformance.dart
 ```
 
 The runner starts `mcp_2025_server.dart`, runs
-`@modelcontextprotocol/conformance@0.2.0-alpha.7 server --suite all
+`@modelcontextprotocol/conformance@0.2.0-alpha.8 server --suite all
 --spec-version 2025-11-25`, and writes artifacts under
 `.dart_tool/conformance/2025_server/`.
 
 Run the stable client suite from the repository root:
 
 ```bash
-npx -y @modelcontextprotocol/conformance@0.2.0-alpha.7 client \
+npx -y @modelcontextprotocol/conformance@0.2.0-alpha.8 client \
   --command "dart run test/conformance/mcp_2026_07_28_rc_client.dart" \
   --suite all \
   --spec-version 2025-11-25 \
@@ -55,14 +55,14 @@ dart run test/conformance/run_2026_07_28_rc_server_conformance.dart
 
 The runner starts a local `StreamableMcpServer` in default Streamable HTTP SSE
 response mode, runs the full `2026-07-28` server scenario list from
-`@modelcontextprotocol/conformance@0.2.0-alpha.7` one by one with `--suite all`
+`@modelcontextprotocol/conformance@0.2.0-alpha.8` one by one with `--suite all`
 and `--spec-version 2026-07-28`, and writes per-run artifacts under
 `.dart_tool/conformance/2026_07_28_rc/`.
 
 Expected failures live in `2026_07_28_rc_expected_failures.txt`. When a scenario is
 fixed, remove it from that file so the baseline remains useful.
 
-As of `@modelcontextprotocol/conformance@0.2.0-alpha.7`, the full 2026-07-28 RC server
+As of `@modelcontextprotocol/conformance@0.2.0-alpha.8`, the full 2026-07-28 RC server
 suite has no expected failures against the Dart fixture.
 
 Run the current client baseline from the repository root:
diff --git a/test/conformance/mcp_2026_07_28_rc_client.dart b/test/conformance/mcp_2026_07_28_rc_client.dart
index b63ff3bf..a6b1cdf5 100644
--- a/test/conformance/mcp_2026_07_28_rc_client.dart
+++ b/test/conformance/mcp_2026_07_28_rc_client.dart
@@ -251,7 +251,6 @@ Future<void> _runCustomHeaders(
       'debug': 'Debug',
       'empty_val': 'EmptyVal',
       'method_val': 'Method',
-      'float_val': 'FloatVal',
       'non_ascii_val': 'NonAscii',
       'whitespace_val': 'Whitespace',
       'leading_space_val': 'LeadingSpace',
diff --git a/test/conformance/mcp_2026_07_28_rc_server.dart b/test/conformance/mcp_2026_07_28_rc_server.dart
index 868c4fe5..3473c1e4 100644
--- a/test/conformance/mcp_2026_07_28_rc_server.dart
+++ b/test/conformance/mcp_2026_07_28_rc_server.dart
@@ -104,12 +104,52 @@ McpServer _createConformanceServer() {
     },
   );
 
+  _registerAlpha8StatelessDiagnostics(server);
   _registerStreamDiagnostics(server);
   _registerInputRequiredDiagnostics(server);
 
   return server;
 }
 
+void _registerAlpha8StatelessDiagnostics(McpServer server) {
+  server.registerTool(
+    'test_missing_capability',
+    description:
+        'Requires sampling so missing client capability handling can be validated',
+    meta: const {
+      'io.modelcontextprotocol/requiredClientCapabilities': ['sampling'],
+    },
+    callback: (args, extra) async {
+      return _textResult('sampling capability present');
+    },
+  );
+
+  server.registerTool(
+    'test_streaming_elicitation',
+    description:
+        'Returns a normal result so response-stream frame shape can be validated',
+    callback: (args, extra) async {
+      return _textResult('stream-shape-ok');
+    },
+  );
+
+  server.registerTool(
+    'test_logging_tool',
+    description:
+        'Attempts request-scoped logging for the stateless log-level diagnostic',
+    callback: (args, extra) async {
+      await server.sendLoggingMessage(
+        const LoggingMessageNotification(
+          level: LoggingLevel.info,
+          data: 'log-level diagnostic',
+        ),
+        requestMeta: extra.meta,
+      );
+      return _textResult('logging-ok');
+    },
+  );
+}
+
 void _registerStreamDiagnostics(McpServer server) {
   server.registerTool(
     'test_stream_cancellation',
diff --git a/test/conformance/run_2025_server_conformance.dart b/test/conformance/run_2025_server_conformance.dart
index e03fd9f4..cf3aa87f 100644
--- a/test/conformance/run_2025_server_conformance.dart
+++ b/test/conformance/run_2025_server_conformance.dart
@@ -3,10 +3,10 @@ import 'dart:convert';
 import 'dart:io';
 
 const _defaultConformancePackage =
-    '@modelcontextprotocol/conformance@0.2.0-alpha.7';
+    '@modelcontextprotocol/conformance@0.2.0-alpha.8';
 const _defaultTimeout = Duration(seconds: 60);
 
-// The alpha.7 conformance CLI occasionally leaks or stalls server-initiated
+// The alpha conformance CLI can occasionally leak or stall server-initiated
 // elicitation state when the complete 2025 server suite is run in one process
 // on GitHub's Linux runners. Running each pinned scenario in a fresh
 // conformance process preserves coverage while isolating CLI-side state.
diff --git a/test/conformance/run_2026_07_28_rc_client_conformance.dart b/test/conformance/run_2026_07_28_rc_client_conformance.dart
index 155254e9..34feddba 100644
--- a/test/conformance/run_2026_07_28_rc_client_conformance.dart
+++ b/test/conformance/run_2026_07_28_rc_client_conformance.dart
@@ -3,7 +3,7 @@ import 'dart:convert';
 import 'dart:io';
 
 const _defaultConformancePackage =
-    '@modelcontextprotocol/conformance@0.2.0-alpha.7';
+    '@modelcontextprotocol/conformance@0.2.0-alpha.8';
 const _defaultTimeout = Duration(seconds: 30);
 
 const _draftClientScenarios = [
diff --git a/test/conformance/run_2026_07_28_rc_server_conformance.dart b/test/conformance/run_2026_07_28_rc_server_conformance.dart
index 321b0cb8..68ccb129 100644
--- a/test/conformance/run_2026_07_28_rc_server_conformance.dart
+++ b/test/conformance/run_2026_07_28_rc_server_conformance.dart
@@ -3,7 +3,7 @@ import 'dart:convert';
 import 'dart:io';
 
 const _defaultConformancePackage =
-    '@modelcontextprotocol/conformance@0.2.0-alpha.7';
+    '@modelcontextprotocol/conformance@0.2.0-alpha.8';
 const _defaultTimeout = Duration(seconds: 25);
 
 const _serverScenarios = [
diff --git a/test/interop/ts_2026_07_28_rc/README.md b/test/interop/ts_2026_07_28_rc/README.md
index 8ed45e4c..8a294f24 100644
--- a/test/interop/ts_2026_07_28_rc/README.md
+++ b/test/interop/ts_2026_07_28_rc/README.md
@@ -5,12 +5,12 @@ This fixture is an experimental smoke test for the unreleased MCP
 progress.
 
 It is intentionally separate from `test/interop/ts`, which tracks the published
-stable TypeScript SDK and MCP `2025-11-25` behavior. The fixture pins
-`pkg.pr.new` client and server previews from the TypeScript SDK
-`v2-2026-07-28` branch after PR #2327 landed. The TypeScript client path is a
-draft-aligned smoke check against the Dart 2026-07-28 RC server. The reverse Dart
-client path is a draft-aligned smoke check against the TypeScript preview
-server.
+stable TypeScript SDK and MCP `2025-11-25` behavior. The fixture pins published
+`@modelcontextprotocol/client@2.0.0-beta.1` and
+`@modelcontextprotocol/server@2.0.0-beta.1` packages. The TypeScript client path
+is a draft-aligned smoke check against the Dart 2026-07-28 RC server. The
+reverse Dart client path is a draft-aligned smoke check against the TypeScript
+beta server.
 
 ## Run
 
@@ -53,10 +53,10 @@ bound local URL, and then runs `src/client.mjs` against it. The fixture asserts:
 - Closing a 2026 HTTP SSE response stream cancels the in-flight Dart server
   request without sending `notifications/cancelled`.
 
-The runner also starts `src/server.mjs` with the TypeScript preview
+The runner also starts `src/server.mjs` with the TypeScript beta
 `createMcpHandler` entry and runs a Dart preview client against it. That reverse
 path asserts `server/discover` negotiation, `tools/list`, and `tools/call`
-against the TypeScript preview server; failures are treated as interop failures.
+against the TypeScript beta server; failures are treated as interop failures.
 
 Keep this fixture anchored to the official draft/RC behavior rather than the
 preview TypeScript implementation alone. In particular, `x-mcp-header` tests use
@@ -67,11 +67,6 @@ assertion source and document the preview gap near the test.
 CI runs this fixture in the dedicated
 `Run MCP 2026-07-28 TypeScript Interop` workflow for relevant PRs,
 `dev/2026-07-28-rc` pushes, daily scheduled drift checks, and manual dispatch.
-Keep the fixture pinned to a published TypeScript SDK alpha once upstream no
-longer requires `pkg.pr.new` preview artifacts. Do not treat publication alone
-as enough to re-pin: `@modelcontextprotocol/client@2.0.0-alpha.3` and
-`@modelcontextprotocol/server@2.0.0-alpha.3` are published, but the published
-client does not expose the preview `versionNegotiation` / `getProtocolEra` APIs
-used here, and a direct `supportedProtocolVersions: ["2026-07-28"]` repin fails
-the handshake. Keep this fixture on the `pkg.pr.new` preview until a published
-package exposes the 2026 draft path and this runner passes against it.
+Keep the fixture pinned to a published TypeScript SDK beta that exposes the
+2026 draft path and passes this runner; do not treat package publication alone
+as enough to re-pin without rerunning the interop check.
diff --git a/test/interop/ts_2026_07_28_rc/package-lock.json b/test/interop/ts_2026_07_28_rc/package-lock.json
index d24447b0..bdbe33f3 100644
--- a/test/interop/ts_2026_07_28_rc/package-lock.json
+++ b/test/interop/ts_2026_07_28_rc/package-lock.json
@@ -9,8 +9,8 @@
       "version": "0.0.0",
       "dependencies": {
         "@cfworker/json-schema": "4.1.1",
-        "@modelcontextprotocol/client": "https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/client@9fdb62e",
-        "@modelcontextprotocol/server": "https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/server@9fdb62e"
+        "@modelcontextprotocol/client": "2.0.0-beta.1",
+        "@modelcontextprotocol/server": "2.0.0-beta.1"
       },
       "engines": {
         "node": ">=20"
@@ -23,9 +23,9 @@
       "license": "MIT"
     },
     "node_modules/@modelcontextprotocol/client": {
-      "version": "2.0.0-alpha.2",
-      "resolved": "https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/client@9fdb62e",
-      "integrity": "sha512-A02KwaeB0p7WJ8TCQB83WLtPpGUK+1h3y4k6IMxfun3VmIiH7jrAw2y72TmSnofwO1GKYr53R142t78sCE5ycg==",
+      "version": "2.0.0-beta.1",
+      "resolved": "https://registry.npmjs.org/@modelcontextprotocol/client/-/client-2.0.0-beta.1.tgz",
+      "integrity": "sha512-1YbnguKN7OFGA/lmCtgIthyE5d+j7dvu7hJld+f0mKrM0YAV4Q8TG80RBto+qyupxhHjTMEWItHu7cQlAmVtyA==",
       "license": "MIT",
       "dependencies": {
         "cross-spawn": "^7.0.5",
@@ -40,9 +40,9 @@
       }
     },
     "node_modules/@modelcontextprotocol/server": {
-      "version": "2.0.0-alpha.2",
-      "resolved": "https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/server@9fdb62e",
-      "integrity": "sha512-4yLquMq4S/d69ISm7XyDsyVDxtih7jGVKCXK1QDqBuxVgFGDN2jY4iZb13kFVD28Wv1IPQ93pHtCEEn7j+0iqw==",
+      "version": "2.0.0-beta.1",
+      "resolved": "https://registry.npmjs.org/@modelcontextprotocol/server/-/server-2.0.0-beta.1.tgz",
+      "integrity": "sha512-83scKauajX9fWbSIC4NBYdnvXajH+cqvX8QqsrPH0XNgqtMmym1kWucMO7YyNkrBD9C7/R+FRCmkjC9kgEKXlQ==",
       "license": "MIT",
       "dependencies": {
         "zod": "^4.2.0"
diff --git a/test/interop/ts_2026_07_28_rc/package.json b/test/interop/ts_2026_07_28_rc/package.json
index 93f537a3..7c870d8d 100644
--- a/test/interop/ts_2026_07_28_rc/package.json
+++ b/test/interop/ts_2026_07_28_rc/package.json
@@ -9,8 +9,8 @@
   },
   "dependencies": {
     "@cfworker/json-schema": "4.1.1",
-    "@modelcontextprotocol/client": "https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/client@9fdb62e",
-    "@modelcontextprotocol/server": "https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/server@9fdb62e"
+    "@modelcontextprotocol/client": "2.0.0-beta.1",
+    "@modelcontextprotocol/server": "2.0.0-beta.1"
   },
   "engines": {
     "node": ">=20"
diff --git a/test/mcp_2026_07_28_test.dart b/test/mcp_2026_07_28_test.dart
index 91081152..bd64c977 100644
--- a/test/mcp_2026_07_28_test.dart
+++ b/test/mcp_2026_07_28_test.dart
@@ -45,6 +45,24 @@ class RecordingTransport extends Transport {
   }
 }
 
+class ValidationRecordingTransport extends RecordingTransport
+    implements IncomingRequestValidationAwareTransport {
+  McpError? Function(JsonRpcRequest request)? incomingRequestValidator;
+  bool Function(String method)? requestMethodSupported;
+
+  @override
+  void setIncomingRequestValidator(
+    McpError? Function(JsonRpcRequest request) validator,
+  ) {
+    incomingRequestValidator = validator;
+  }
+
+  @override
+  void setRequestMethodSupported(bool Function(String method) isSupported) {
+    requestMethodSupported = isSupported;
+  }
+}
+
 class SessionRecordingTaskStore extends InMemoryTaskStore {
   final List<String?> createTaskSessionIds = [];
   final List<String?> updateTaskStatusSessionIds = [];
@@ -2991,6 +3009,59 @@ void main() {
       );
     });
 
+    test('stateless tools/call rejects missing tool-required client capability',
+        () async {
+      final server = McpServer(
+        const Implementation(name: 'server', version: '1.0.0'),
+        options: const McpServerOptions(
+          protocol: McpProtocol.preview2026,
+        ),
+      );
+      server.registerTool(
+        'needs_sampling',
+        meta: const {
+          'io.modelcontextprotocol/requiredClientCapabilities': ['sampling'],
+        },
+        callback: (args, extra) => const CallToolResult(
+          content: [TextContent(text: 'ok')],
+        ),
+      );
+      final transport = ValidationRecordingTransport();
+      await server.connect(transport);
+      final validator = transport.incomingRequestValidator;
+      expect(validator, isNotNull);
+
+      final missingError = validator!(
+        JsonRpcCallToolRequest(
+          id: 'call-1',
+          params: const CallToolRequest(name: 'needs_sampling').toJson(),
+          meta: _clientMeta(),
+        ),
+      );
+
+      expect(missingError, isNotNull);
+      expect(
+        missingError!.code,
+        ErrorCode.missingRequiredClientCapability.value,
+      );
+      expect(missingError.data, {
+        'requiredCapabilities': ['sampling'],
+      });
+
+      final allowedError = validator(
+        JsonRpcCallToolRequest(
+          id: 'call-2',
+          params: const CallToolRequest(name: 'needs_sampling').toJson(),
+          meta: _clientMeta(
+            clientCapabilities: const ClientCapabilities(
+              sampling: ClientCapabilitiesSampling(tools: true),
+            ),
+          ),
+        ),
+      );
+      expect(allowedError, isNull);
+    });
+
     test('stateless tools/call ignores legacy task parameter', () async {
       final server = McpServer(
         const Implementation(name: 'server', version: '1.0.0'),