diff --git a/.changeset/remove-protocol-era.md b/.changeset/remove-protocol-era.md
new file mode 100644
index 000000000..11bf253b1
--- /dev/null
+++ b/.changeset/remove-protocol-era.md
@@ -0,0 +1,5 @@
+---
+"agent-bundle": minor
+---
+
+Remove `protocolEra` from `DevRuntimeMcpConnectionState` (exported from `agent-bundle/api`) and from the dev server's runtime MCP session snapshots. The MCP client never reported a protocol era, so the field was always absent; runtime MCP App previews no longer refuse a live session for lacking it. (#836)
diff --git a/examples/rsc-agent-runtime/src/dev/rsbuild-runtime-session.ts b/examples/rsc-agent-runtime/src/dev/rsbuild-runtime-session.ts
index 06d67ea3d..3154588bf 100644
--- a/examples/rsc-agent-runtime/src/dev/rsbuild-runtime-session.ts
+++ b/examples/rsc-agent-runtime/src/dev/rsbuild-runtime-session.ts
@@ -800,7 +800,6 @@ export class RsbuildRuntimeSession implements DevRuntimeSession {
           resources: Object.freeze({}),
           tools: Object.freeze({}),
         }),
-        protocolEra: 'modern',
         protocolVersion: '2025-06-18',
         server: Object.freeze({ name: projectName, version: projectVersion }),
       });
diff --git a/packages/agent-bundle/src/dev/mcp-app-runtime-preview-service.ts b/packages/agent-bundle/src/dev/mcp-app-runtime-preview-service.ts
index 3b382841c..305322864 100644
--- a/packages/agent-bundle/src/dev/mcp-app-runtime-preview-service.ts
+++ b/packages/agent-bundle/src/dev/mcp-app-runtime-preview-service.ts
@@ -365,7 +365,7 @@ export class McpAppRuntimePreviewService implements McpAppRuntimeRoutePreviewSer
       throw new Error('Runtime MCP App stable session has foreign provider/state authority.');
     }
     if (
-      live.connection.protocolEra === undefined || live.connection.protocolVersion === undefined ||
+      live.connection.protocolVersion === undefined ||
       live.connection.capabilities === undefined || live.connection.server === undefined
     ) {
       throw new Error('Runtime MCP App stable session has incomplete negotiation.');
diff --git a/packages/agent-bundle/src/dev/mcp-session/mcp-session-types.ts b/packages/agent-bundle/src/dev/mcp-session/mcp-session-types.ts
index fa606aebf..38df5e019 100644
--- a/packages/agent-bundle/src/dev/mcp-session/mcp-session-types.ts
+++ b/packages/agent-bundle/src/dev/mcp-session/mcp-session-types.ts
@@ -52,7 +52,6 @@ export interface McpClient {
   getServerCapabilities(): ServerCapabilities | undefined;
   getServerVersion(): Implementation | undefined;
   getNegotiatedProtocolVersion?(): string | undefined;
-  getProtocolEra?(): 'legacy' | 'modern' | undefined;
   listPrompts(params?: undefined, options?: McpRequestOptions): Promise<{ readonly prompts: readonly Prompt[] }>;
   listResources(params?: undefined, options?: McpRequestOptions): Promise<{ readonly resources: readonly Resource[] }>;
   listResourceTemplates(
@@ -146,7 +145,6 @@ export interface McpSessionResourceOptions extends McpSessionRequestOptions {
 
 export interface McpSessionConnectionState {
   readonly capabilities: ServerCapabilities | undefined;
-  readonly protocolEra: 'legacy' | 'modern' | undefined;
   readonly protocolVersion: string | undefined;
   readonly server: Implementation | undefined;
 }
diff --git a/packages/agent-bundle/src/dev/mcp-session/mcp-session.ts b/packages/agent-bundle/src/dev/mcp-session/mcp-session.ts
index f4c2e0a11..2186e3b1b 100644
--- a/packages/agent-bundle/src/dev/mcp-session/mcp-session.ts
+++ b/packages/agent-bundle/src/dev/mcp-session/mcp-session.ts
@@ -640,7 +640,6 @@ export class McpSession {
           this.#capture = connectState.capture;
           this.#connection = Object.freeze({
             capabilities: client.getServerCapabilities(),
-            protocolEra: client.getProtocolEra?.(),
             protocolVersion: client.getNegotiatedProtocolVersion?.(),
             server: client.getServerVersion(),
           });
diff --git a/packages/agent-bundle/src/dev/runtime-mcp-registry.ts b/packages/agent-bundle/src/dev/runtime-mcp-registry.ts
index 03a6ccd0d..dcba6a3da 100644
--- a/packages/agent-bundle/src/dev/runtime-mcp-registry.ts
+++ b/packages/agent-bundle/src/dev/runtime-mcp-registry.ts
@@ -1154,7 +1154,6 @@ const bindingCopy = (binding: DevRuntimeMcpSessionBinding): DevRuntimeMcpInvalid
 
 const finiteConnectionState = (input: DevRuntimeMcpConnectionState): DevRuntimeMcpConnectionState => Object.freeze({
   capabilities: input.capabilities === undefined ? undefined : jsonObject(input.capabilities, 'Runtime MCP connection capabilities'),
-  protocolEra: input.protocolEra,
   protocolVersion: input.protocolVersion,
   server: input.server === undefined ? undefined : Object.freeze({
     name: nonempty(input.server.name, 'Runtime MCP connection server name'),
diff --git a/packages/agent-bundle/src/dev/runtime-mcp-routes.ts b/packages/agent-bundle/src/dev/runtime-mcp-routes.ts
index dff8203dd..295bc92a4 100644
--- a/packages/agent-bundle/src/dev/runtime-mcp-routes.ts
+++ b/packages/agent-bundle/src/dev/runtime-mcp-routes.ts
@@ -132,7 +132,6 @@ const publicSessionSnapshot = (snapshot: DevRuntimeMcpSessionSnapshot): PublicRu
     }),
     connection: Object.freeze({
       capabilities: snapshot.connection.capabilities,
-      protocolEra: snapshot.connection.protocolEra,
       protocolVersion: snapshot.connection.protocolVersion,
       server: server === undefined ? undefined : Object.freeze({ name: server.name, version: server.version }),
     }),
diff --git a/packages/agent-bundle/src/dev/runtime-protocol.ts b/packages/agent-bundle/src/dev/runtime-protocol.ts
index 43f9188f6..52e1f4348 100644
--- a/packages/agent-bundle/src/dev/runtime-protocol.ts
+++ b/packages/agent-bundle/src/dev/runtime-protocol.ts
@@ -223,7 +223,6 @@ export interface DevRuntimeMcpRegistrySnapshot {
 
 export interface DevRuntimeMcpConnectionState {
   readonly capabilities: JsonObject | undefined;
-  readonly protocolEra: 'legacy' | 'modern' | undefined;
   readonly protocolVersion: string | undefined;
   readonly server: Readonly<{ readonly name: string; readonly version: string }> | undefined;
 }
diff --git a/packages/agent-bundle/tests/dev-server.test.ts b/packages/agent-bundle/tests/dev-server.test.ts
index b4a8053d4..c41e4b8c1 100644
--- a/packages/agent-bundle/tests/dev-server.test.ts
+++ b/packages/agent-bundle/tests/dev-server.test.ts
@@ -932,7 +932,7 @@ it('applies the established foreground origin and token guard to MCP session cre
       opens.push(options);
       return {
         binding: { epochId: 'epoch-a', serverName: 'weather', target: 'portable' },
-        connection: { capabilities: {}, protocolEra: 'modern', protocolVersion: '2025-11-25', server: { name: 'fixture', version: '1.0.0' } },
+        connection: { capabilities: {}, protocolVersion: '2025-11-25', server: { name: 'fixture', version: '1.0.0' } },
         id: 'session-a',
       };
     },
@@ -971,7 +971,7 @@ it('applies the established foreground origin and token guard to MCP session cre
     await expect(accepted.json()).resolves.toEqual({
       session: {
         binding: { epochId: 'epoch-a', serverName: 'weather', target: 'portable' },
-        connection: { capabilities: {}, protocolEra: 'modern', protocolVersion: '2025-11-25', server: { name: 'fixture', version: '1.0.0' } },
+        connection: { capabilities: {}, protocolVersion: '2025-11-25', server: { name: 'fixture', version: '1.0.0' } },
         id: 'session-a',
       },
     });
@@ -986,7 +986,7 @@ it('accepts headerless browser same-origin fetch provenance with the exact token
   let streamSubscriptions = 0;
   const session = {
     binding: { epochId: 'epoch-a', serverName: 'weather', target: 'portable' },
-    connection: { capabilities: {}, protocolEra: 'modern', protocolVersion: '2025-11-25', server: { name: 'fixture', version: '1.0.0' } },
+    connection: { capabilities: {}, protocolVersion: '2025-11-25', server: { name: 'fixture', version: '1.0.0' } },
     id: 'session-a',
     subscribeTrace: () => {
       streamSubscriptions += 1;
@@ -1120,7 +1120,7 @@ it('ends active authenticated MCP trace readers before foreground shutdown destr
   let subscriptions = 0;
   const session = {
     binding: { epochId: 'epoch-a', serverName: 'weather', target: 'portable' },
-    connection: { capabilities: {}, protocolEra: 'modern', protocolVersion: '2025-11-25', server: { name: 'fixture', version: '1.0.0' } },
+    connection: { capabilities: {}, protocolVersion: '2025-11-25', server: { name: 'fixture', version: '1.0.0' } },
     id: 'session-a',
     subscribeTrace: () => {
       subscriptions += 1;
diff --git a/packages/agent-bundle/tests/mcp-app-runtime-binding-service.test.ts b/packages/agent-bundle/tests/mcp-app-runtime-binding-service.test.ts
index 22fd46bc5..f4b30a33b 100644
--- a/packages/agent-bundle/tests/mcp-app-runtime-binding-service.test.ts
+++ b/packages/agent-bundle/tests/mcp-app-runtime-binding-service.test.ts
@@ -39,7 +39,7 @@ const runVector: RuntimeVector = Object.freeze({
 
 const sessionSnapshot = (): DevRuntimeMcpSessionSnapshot => Object.freeze({
   binding: Object.freeze({ ...runBinding, providerSessionId: 'provider-private', stateStoreId: 'state-private' }),
-  connection: Object.freeze({ capabilities: undefined, protocolEra: 'modern', protocolVersion: '2026-01-26', server: undefined }),
+  connection: Object.freeze({ capabilities: undefined, protocolVersion: '2026-01-26', server: undefined }),
   state: 'ready',
 });
 
diff --git a/packages/agent-bundle/tests/mcp-app-runtime-preview-service.test.ts b/packages/agent-bundle/tests/mcp-app-runtime-preview-service.test.ts
index deabb2450..342893bfe 100644
--- a/packages/agent-bundle/tests/mcp-app-runtime-preview-service.test.ts
+++ b/packages/agent-bundle/tests/mcp-app-runtime-preview-service.test.ts
@@ -51,7 +51,6 @@ const snapshot = (): DevRuntimeMcpSessionSnapshot => Object.freeze({
   }),
   connection: Object.freeze({
     capabilities: Object.freeze({ resources: Object.freeze({}), tools: Object.freeze({}) }),
-    protocolEra: 'modern' as const,
     protocolVersion: '2026-01-26',
     server: Object.freeze({ name: 'weather', version: '1.0.0' }),
   }),
diff --git a/packages/agent-bundle/tests/mcp-session-routes.test.ts b/packages/agent-bundle/tests/mcp-session-routes.test.ts
index b2613cc4f..a2db8a968 100644
--- a/packages/agent-bundle/tests/mcp-session-routes.test.ts
+++ b/packages/agent-bundle/tests/mcp-session-routes.test.ts
@@ -29,7 +29,7 @@ const startRoutes = async (service: McpSessionRouteService): Promise<StartedRout
 
 class RecordingSession implements McpSessionRouteSession {
   readonly binding = Object.freeze({ epochId: 'epoch-a', serverName: 'weather', target: 'portable' });
-  readonly connection = Object.freeze({ capabilities: { tools: {} }, protocolEra: 'modern' as const, protocolVersion: '2025-11-25', server: { name: 'fixture', version: '1.0.0' } });
+  readonly connection = Object.freeze({ capabilities: { tools: {} }, protocolVersion: '2025-11-25', server: { name: 'fixture', version: '1.0.0' } });
   readonly id = 'session-a';
   readonly timeoutMs = 5_000;
   readonly calls: unknown[] = [];
diff --git a/packages/agent-bundle/tests/mcp-session-service.test.ts b/packages/agent-bundle/tests/mcp-session-service.test.ts
index 8d5768400..dd010ed71 100644
--- a/packages/agent-bundle/tests/mcp-session-service.test.ts
+++ b/packages/agent-bundle/tests/mcp-session-service.test.ts
@@ -1673,7 +1673,6 @@ it('exposes one opaque, epoch-bound session handle with a bounded ordered wire t
           transport.onmessage?.(progressFrame);
         },
         getNegotiatedProtocolVersion: () => '2026-07-28',
-        getProtocolEra: () => 'modern' as const,
         getPrompt: async () => ({ messages: [] }),
         getServerCapabilities: () => ({ logging: {} }),
         getServerVersion: () => ({ name: 'wire-fixture', version: '1.0.0' }),
@@ -1695,7 +1694,6 @@ it('exposes one opaque, epoch-bound session handle with a bounded ordered wire t
     expect(session.binding).toEqual({ epochId: 'epoch-wire', serverName: 'fixture', target: 'portable' });
     expect(Object.isFrozen(session.binding)).toBe(true);
     expect(session.connection).toMatchObject({
-      protocolEra: 'modern',
       protocolVersion: '2026-07-28',
       server: { name: 'wire-fixture', version: '1.0.0' },
     });
diff --git a/packages/agent-bundle/tests/runtime-mcp-registry.test.ts b/packages/agent-bundle/tests/runtime-mcp-registry.test.ts
index 28d0668de..3d810b912 100644
--- a/packages/agent-bundle/tests/runtime-mcp-registry.test.ts
+++ b/packages/agent-bundle/tests/runtime-mcp-registry.test.ts
@@ -39,7 +39,6 @@ const deferred = <T = void>(): Readonly<{
 
 const connectionState: DevRuntimeMcpConnectionState = Object.freeze({
   capabilities: Object.freeze({ tools: Object.freeze({}) }),
-  protocolEra: 'modern',
   protocolVersion: '2025-06-18',
   server: Object.freeze({ name: 'fixture', version: '1.0.0' }),
 });
diff --git a/packages/agent-bundle/tests/runtime-mcp-routes.test.ts b/packages/agent-bundle/tests/runtime-mcp-routes.test.ts
index 2dd18d028..ac685ea78 100644
--- a/packages/agent-bundle/tests/runtime-mcp-routes.test.ts
+++ b/packages/agent-bundle/tests/runtime-mcp-routes.test.ts
@@ -25,7 +25,6 @@ it('delegates the fixed manual runtime MCP open route without becoming an App pr
     }),
     connection: Object.freeze({
       capabilities: Object.freeze({}),
-      protocolEra: 'modern' as const,
       protocolVersion: '2026-01-26',
       server: Object.freeze({ name: 'weather', providerSessionId: 'provider-private', stateStoreId: 'state-private', unexpected: 'unexpected-value', version: '1.0.0' }),
     }),
@@ -38,7 +37,6 @@ it('delegates the fixed manual runtime MCP open route without becoming an App pr
     }),
     connection: Object.freeze({
       capabilities: Object.freeze({ tools: Object.freeze({ listChanged: true }) }),
-      protocolEra: 'modern' as const,
       protocolVersion: '2026-02-09',
       server: Object.freeze({ name: 'weather-next', providerSessionId: 'provider-private', stateStoreId: 'state-private', unexpected: 'unexpected-value', version: '2.0.0' }),
     }),
@@ -92,7 +90,7 @@ it('delegates the fixed manual runtime MCP open route without becoming an App pr
     expect(opened).toEqual({ session: { binding: {
       definitionDigest: 'definition-a', registryRevision: 3, serverDigest: 'server-a', serverName: 'weather',
       sessionId: 'session-a', sessionRevision: 2, target: 'portable', transportDigest: 'transport-a',
-    }, connection: { capabilities: {}, protocolEra: 'modern', protocolVersion: '2026-01-26', server: { name: 'weather', version: '1.0.0' } }, state: 'ready' } });
+    }, connection: { capabilities: {}, protocolVersion: '2026-01-26', server: { name: 'weather', version: '1.0.0' } }, state: 'ready' } });
     expect(JSON.stringify(opened)).not.toContain('provider-private');
     expect(JSON.stringify(opened)).not.toContain('state-private');
 
@@ -113,7 +111,7 @@ it('delegates the fixed manual runtime MCP open route without becoming an App pr
           definitionDigest: 'definition-b', registryRevision: 4, serverDigest: 'server-b', serverName: 'weather',
           sessionId: 'session-a', sessionRevision: 3, target: 'portable', transportDigest: 'transport-b',
         },
-        connection: { capabilities: { tools: { listChanged: true } }, protocolEra: 'modern', protocolVersion: '2026-02-09', server: { name: 'weather-next', version: '2.0.0' } },
+        connection: { capabilities: { tools: { listChanged: true } }, protocolVersion: '2026-02-09', server: { name: 'weather-next', version: '2.0.0' } },
         state: 'ready',
       },
     });
@@ -136,7 +134,7 @@ it('claims manual runtime MCP routes before the generic runtime browser API', as
           snapshot: () => Object.freeze({ binding: Object.freeze({
             definitionDigest: 'definition-a', providerSessionId: 'provider-private', registryRevision: 3, serverDigest: 'server-a', serverName: 'weather',
             sessionId: 'session-a', sessionRevision: 2, stateStoreId: 'state-private', target: 'portable', transportDigest: 'transport-a',
-          }), connection: Object.freeze({ capabilities: Object.freeze({}), protocolEra: 'modern' as const, protocolVersion: '2026-01-26', server: undefined }), state: 'ready' as const }),
+          }), connection: Object.freeze({ capabilities: Object.freeze({}), protocolVersion: '2026-01-26', server: undefined }), state: 'ready' as const }),
           watchClosed: () => Object.freeze({ closed: false, unsubscribe: () => undefined }),
         });
       },
diff --git a/packages/workbench/src/mcp/mcp-app-client.ts b/packages/workbench/src/mcp/mcp-app-client.ts
index 2fdfb88c3..e9166065f 100644
--- a/packages/workbench/src/mcp/mcp-app-client.ts
+++ b/packages/workbench/src/mcp/mcp-app-client.ts
@@ -312,11 +312,6 @@ const runtimeStringOrUndefined = (value: unknown, label: string): string | undef
   return runtimeInvalid(`Runtime MCP App route returned an invalid ${label}.`);
 };
 
-const runtimeEra = (value: unknown): 'legacy' | 'modern' | undefined => {
-  if (value === undefined || value === 'legacy' || value === 'modern') return value;
-  return runtimeInvalid('Runtime MCP App route returned an invalid protocol era.');
-};
-
 const runtimeProfileId = (value: unknown): 'portable' | 'chatgpt' | 'claude' => {
   if (value === 'portable' || value === 'chatgpt' || value === 'claude') return value;
   return runtimeInvalid('Runtime MCP App route returned an invalid profile.');
@@ -389,19 +384,16 @@ const runtimeBinding = (value: unknown): McpAppRuntimeBindingSnapshot => {
 
 const runtimeConnection = (value: unknown): Readonly<{
   readonly capabilities: Readonly<Record<string, McpAppJsonValue>> | undefined;
-  readonly protocolEra: 'legacy' | 'modern' | undefined;
   readonly protocolVersion: string | undefined;
   readonly server: Readonly<{ readonly name: string; readonly version: string }> | undefined;
 }> => {
-  const record = runtimeRecord(value, ['capabilities', 'protocolEra', 'protocolVersion', 'server']);
+  const record = runtimeRecord(value, ['capabilities', 'protocolVersion', 'server']);
   if (record.capabilities !== undefined && !isRecord(record.capabilities)) runtimeInvalid('Runtime MCP App route returned invalid server capabilities.');
   const server = record.server === undefined ? undefined : runtimeRecord(record.server, ['name', 'version']);
   const capabilities = record.capabilities === undefined ? undefined : asRecord(record.capabilities);
-  const protocolEra = runtimeEra(record.protocolEra);
   const protocolVersion = runtimeStringOrUndefined(record.protocolVersion, 'protocol version');
   return Object.freeze({
     capabilities,
-    protocolEra,
     protocolVersion,
     server: server === undefined ? undefined : Object.freeze({ name: runtimeText(server.name, 'server name'), version: runtimeText(server.version, 'server version') }),
   });
diff --git a/packages/workbench/src/mcp/mcp-route-client.ts b/packages/workbench/src/mcp/mcp-route-client.ts
index f7236b4b1..5c13adfd3 100644
--- a/packages/workbench/src/mcp/mcp-route-client.ts
+++ b/packages/workbench/src/mcp/mcp-route-client.ts
@@ -22,7 +22,6 @@ export interface McpRouteSessionBinding {
 
 export interface McpRouteConnection {
   readonly capabilities?: unknown;
-  readonly protocolEra?: 'legacy' | 'modern';
   readonly protocolVersion?: string;
   readonly server?: Readonly<{ readonly name: string; readonly version: string }>;
 }
@@ -220,15 +219,13 @@ const routeConnection = (value: unknown): McpRouteConnection => {
     serverSnapshot = Object.freeze({ name: server.name, version: server.version });
   }
   if (
-    !hasOnlyKeys(connection, ['capabilities', 'protocolEra', 'protocolVersion', 'server']) ||
-    (connection.protocolEra !== undefined && connection.protocolEra !== 'legacy' && connection.protocolEra !== 'modern') ||
+    !hasOnlyKeys(connection, ['capabilities', 'protocolVersion', 'server']) ||
     (connection.protocolVersion !== undefined && typeof connection.protocolVersion !== 'string')
   ) {
     throw new McpRouteClientError('AB8019', 'Foreground MCP route returned an invalid connection.');
   }
   return Object.freeze({
     ...(connection.capabilities === undefined ? {} : { capabilities: connection.capabilities }),
-    ...(connection.protocolEra === undefined ? {} : { protocolEra: connection.protocolEra }),
     ...(connection.protocolVersion === undefined ? {} : { protocolVersion: connection.protocolVersion }),
     ...(serverSnapshot === undefined ? {} : { server: serverSnapshot }),
   });
diff --git a/packages/workbench/src/mcp/mcp-session-controller.ts b/packages/workbench/src/mcp/mcp-session-controller.ts
index e41752310..b6cac9d45 100644
--- a/packages/workbench/src/mcp/mcp-session-controller.ts
+++ b/packages/workbench/src/mcp/mcp-session-controller.ts
@@ -294,7 +294,6 @@ const isRuntimeBinding = (value: unknown): value is DevRuntimeMcpAppRunBinding =
 
 const isRuntimeConnection = (value: unknown): value is McpRouteConnection => {
   if (!isRecord(value)) return false;
-  if (value.protocolEra !== undefined && value.protocolEra !== 'legacy' && value.protocolEra !== 'modern') return false;
   if (value.protocolVersion !== undefined && typeof value.protocolVersion !== 'string') return false;
   if (value.server !== undefined && (!isRecord(value.server) || typeof value.server.name !== 'string' || typeof value.server.version !== 'string')) return false;
   return true;
diff --git a/packages/workbench/tests/agent-bundle-remote-transport.test.ts b/packages/workbench/tests/agent-bundle-remote-transport.test.ts
index 9db1f1bbc..c18a0f947 100644
--- a/packages/workbench/tests/agent-bundle-remote-transport.test.ts
+++ b/packages/workbench/tests/agent-bundle-remote-transport.test.ts
@@ -63,7 +63,6 @@ const cancellableStream = (): Readonly<{ readonly cancelled: () => boolean; read
 const binding = Object.freeze({ epochId: 'epoch-a', serverName: 'weather', target: 'portable' });
 const connection = Object.freeze({
   capabilities: { tools: {} },
-  protocolEra: 'modern',
   protocolVersion: '2025-11-25',
   server: { name: 'weather-fixture', version: '1.0.0' },
 });
@@ -685,7 +684,7 @@ it('uses only exact runtime MCP routes and preserves the operation vector', asyn
     },
     connection: {
       capabilities: { resources: { listChanged: true }, tools: { listChanged: true } },
-      protocolEra: 'modern', protocolVersion: '2026-02-09', server: { name: 'weather-next', version: '2.0.0' },
+      protocolVersion: '2026-02-09', server: { name: 'weather-next', version: '2.0.0' },
     },
     state: 'ready',
   };
diff --git a/packages/workbench/tests/mcp-app-client.test.ts b/packages/workbench/tests/mcp-app-client.test.ts
index bf8e8123f..63a22c22b 100644
--- a/packages/workbench/tests/mcp-app-client.test.ts
+++ b/packages/workbench/tests/mcp-app-client.test.ts
@@ -146,7 +146,7 @@ const runtimePreview = Object.freeze({
       definitionDigest: 'definition-a', registryRevision: 3, serverDigest: 'server-a', serverName: 'weather',
       sessionId: 'runtime-session-a', sessionRevision: 2, target: 'portable', transportDigest: 'transport-a',
     }),
-    connection: Object.freeze({ capabilities: Object.freeze({ tools: Object.freeze({}) }), protocolEra: 'modern', protocolVersion: '2026-01-26', server: Object.freeze({ name: 'weather', version: '1.0.0' }) }),
+    connection: Object.freeze({ capabilities: Object.freeze({ tools: Object.freeze({}) }), protocolVersion: '2026-01-26', server: Object.freeze({ name: 'weather', version: '1.0.0' }) }),
     state: 'ready',
   }),
 });
diff --git a/packages/workbench/tests/mcp-app-frame.test.ts b/packages/workbench/tests/mcp-app-frame.test.ts
index 7d5b9c006..eada247c2 100644
--- a/packages/workbench/tests/mcp-app-frame.test.ts
+++ b/packages/workbench/tests/mcp-app-frame.test.ts
@@ -117,7 +117,7 @@ const mountedSecureRendererFixture = async () => {
     `const bootstrapUrl = ${JSON.stringify(bootstrapUrl)};`,
     "const policy = { allow: '', approvedPermissions: {}, revision: 1, warnings: [] };",
     "const metadata = { extensions: { claude: {}, openai: {} }, provenance: {}, raw: {}, standard: {} };",
-    "const preview = { binding: { definitionDigest: 'definition-a', evidence: 'simulated', id: 'runtime-binding', profileId: 'portable', profileVersion: 'agent-bundle:mcp-apps:2026-01-26', registryRevision: 3, runVector: { runtimeGenerationId: 'generation-a', sourceRevision: 'source-a', stateVersion: 1 }, serverDigest: 'server-a', serverName: 'weather', sessionId: 'runtime-session-a', sessionRevision: 2, target: 'portable', transportDigest: 'transport-a' }, clientSurface: { bootstrapUrl, origin: new URL(bootstrapUrl).origin }, documentPolicy: policy, kind: 'apps', metadata: { resource: metadata, result: metadata, tool: metadata }, operations: [], profile: { bootstrap: { kind: 'none' }, configExtensions: { entries: [], sourceRevision: 'source-a' }, descriptor: { claimsRealHostParity: false, evidence: 'simulated', id: 'portable', label: 'Portable MCP Apps', version: 'agent-bundle:mcp-apps:2026-01-26' }, hostContext: { availableDisplayModes: ['inline'], containerDimensions: { height: 720, width: 1024 }, deviceCapabilities: {}, displayMode: 'inline', locale: 'en-US', platform: 'web', safeAreaInsets: { bottom: 0, left: 0, right: 0, top: 0 }, styles: {}, theme: 'light', timeZone: 'UTC', toolInfo: {}, userAgent: 'agent-bundle-runtime-mcp-app/1' }, kind: 'apps', metadata, permissions: { camera: {}, geolocation: {} }, resourceUri: 'ui://weather/app.html', warnings: [] }, resource: { html: '<main>Weather</main>', permissions: { camera: {}, geolocation: {} } }, result: { appVisible: { content: [] }, isError: false, modelVisible: {} }, session: { binding: { definitionDigest: 'definition-a', registryRevision: 3, serverDigest: 'server-a', serverName: 'weather', sessionId: 'runtime-session-a', sessionRevision: 2, target: 'portable', transportDigest: 'transport-a' }, connection: { capabilities: { tools: {} }, protocolEra: 'modern', protocolVersion: '2026-01-26', server: { name: 'weather', version: '1.0.0' } }, state: 'ready' } };",
+    "const preview = { binding: { definitionDigest: 'definition-a', evidence: 'simulated', id: 'runtime-binding', profileId: 'portable', profileVersion: 'agent-bundle:mcp-apps:2026-01-26', registryRevision: 3, runVector: { runtimeGenerationId: 'generation-a', sourceRevision: 'source-a', stateVersion: 1 }, serverDigest: 'server-a', serverName: 'weather', sessionId: 'runtime-session-a', sessionRevision: 2, target: 'portable', transportDigest: 'transport-a' }, clientSurface: { bootstrapUrl, origin: new URL(bootstrapUrl).origin }, documentPolicy: policy, kind: 'apps', metadata: { resource: metadata, result: metadata, tool: metadata }, operations: [], profile: { bootstrap: { kind: 'none' }, configExtensions: { entries: [], sourceRevision: 'source-a' }, descriptor: { claimsRealHostParity: false, evidence: 'simulated', id: 'portable', label: 'Portable MCP Apps', version: 'agent-bundle:mcp-apps:2026-01-26' }, hostContext: { availableDisplayModes: ['inline'], containerDimensions: { height: 720, width: 1024 }, deviceCapabilities: {}, displayMode: 'inline', locale: 'en-US', platform: 'web', safeAreaInsets: { bottom: 0, left: 0, right: 0, top: 0 }, styles: {}, theme: 'light', timeZone: 'UTC', toolInfo: {}, userAgent: 'agent-bundle-runtime-mcp-app/1' }, kind: 'apps', metadata, permissions: { camera: {}, geolocation: {} }, resourceUri: 'ui://weather/app.html', warnings: [] }, resource: { html: '<main>Weather</main>', permissions: { camera: {}, geolocation: {} } }, result: { appVisible: { content: [] }, isError: false, modelVisible: {} }, session: { binding: { definitionDigest: 'definition-a', registryRevision: 3, serverDigest: 'server-a', serverName: 'weather', sessionId: 'runtime-session-a', sessionRevision: 2, target: 'portable', transportDigest: 'transport-a' }, connection: { capabilities: { tools: {} }, protocolVersion: '2026-01-26', server: { name: 'weather', version: '1.0.0' } }, state: 'ready' } };",
     "const response = (body) => new Response(JSON.stringify(body), { headers: { 'content-type': 'application/json' }, status: 200 });",
     "const foreground = new ForegroundRouteClient({ fetch: async (input, init) => { const path = new URL(String(input), location.origin).pathname; if (path === '/api/project/session') return response({ cookieName: 'agent-bundle-foreground-session-0123456789abcdef0123456789abcdef', instanceId: 'foreground-instance-a', origin: location.origin, token: 'foreground-secret' }); if (path === '/api/runtime/apps') return response({ preview }); if (path === '/api/runtime/apps/runtime-binding' && init?.method === 'DELETE') return response({ closed: true }); throw new Error('Unexpected runtime fixture request ' + path); } }); const runtime = new McpAppClient({ foreground });",
     "const trace = []; const iframeNodes = new Set();",
diff --git a/packages/workbench/tests/mcp-app-preview-browser.test.ts b/packages/workbench/tests/mcp-app-preview-browser.test.ts
index a006c5727..731b7d4b4 100644
--- a/packages/workbench/tests/mcp-app-preview-browser.test.ts
+++ b/packages/workbench/tests/mcp-app-preview-browser.test.ts
@@ -60,7 +60,7 @@ const mountedPreviewFixture = async () => {
     `const runtimeBootstrapUrl = ${JSON.stringify(bootstrapUrl)};`,
     "const response = (body) => new Response(JSON.stringify(body), { headers: { 'content-type': 'application/json' }, status: 200 });",
     "const initialRuntimePolicy = () => ({ allow: '', approvedPermissions: {}, revision: 1, warnings: [] });",
-    "const runtimePreviewFor = (suffix) => { const generation = 'generation-' + suffix; const source = 'source-' + suffix; const sessionId = 'runtime-session-' + suffix; const bindingId = 'runtime-binding-' + suffix; const binding = { definitionDigest: 'definition-' + suffix, evidence: 'simulated', id: bindingId, profileId: 'portable', profileVersion: 'agent-bundle:mcp-apps:2026-01-26', registryRevision: 3, runVector: { runtimeGenerationId: generation, sourceRevision: source, stateVersion: suffix === 'a' ? 1 : 2 }, serverDigest: 'server-' + suffix, serverName: 'weather', sessionId, sessionRevision: suffix === 'a' ? 2 : 3, target: 'weather', transportDigest: 'transport-' + suffix }; const stable = { definitionDigest: binding.definitionDigest, registryRevision: binding.registryRevision, serverDigest: binding.serverDigest, serverName: binding.serverName, sessionId: binding.sessionId, sessionRevision: binding.sessionRevision, target: binding.target, transportDigest: binding.transportDigest }; const metadata = { extensions: { claude: { nativeHooks: 'native-hooks-must-stay-hidden', opaque: 'opaque-value-must-stay-hidden', root: '/private/workspace/agent-bundle.config.ts' }, openai: { opaque: 'unregistered-openai-must-stay-hidden' } }, provenance: {}, raw: {}, standard: {} }; const configExtensions = { entries: [{ configured: true, id: 'extension:claude', key: 'claude', provenance: { kind: 'config', sourcePath: 'agent-bundle.config.ts' }, target: 'claude' }, { configured: true, id: 'extension:codex', key: 'codex', provenance: { kind: 'config', sourcePath: 'agent-bundle.config.ts' }, target: 'codex' }, { configured: true, id: 'extension:portable', key: 'portable', provenance: { kind: 'config', sourcePath: 'agent-bundle.config.ts' }, target: 'portable' }], sourceRevision: source }; return { binding, clientSurface: { bootstrapUrl: runtimeBootstrapUrl, origin: new URL(runtimeBootstrapUrl).origin }, documentPolicy: initialRuntimePolicy(), kind: 'apps', metadata: { resource: metadata, result: metadata, tool: metadata }, operations: [], profile: { bootstrap: { kind: 'none' }, configExtensions, descriptor: { claimsRealHostParity: false, evidence: 'simulated', id: 'portable', label: 'Portable MCP Apps', version: 'agent-bundle:mcp-apps:2026-01-26' }, hostContext: { availableDisplayModes: ['inline'], containerDimensions: { height: 720, width: 1024 }, deviceCapabilities: {}, displayMode: 'inline', locale: 'en-US', platform: 'web', safeAreaInsets: { bottom: 0, left: 0, right: 0, top: 0 }, styles: {}, theme: 'light', timeZone: 'UTC', toolInfo: {}, userAgent: 'agent-bundle-runtime-mcp-app/1' }, kind: 'apps', metadata, permissions: { camera: {} }, resourceUri: 'ui://weather/app.html', warnings: [] }, resource: { html: '<main>Weather</main>', permissions: { camera: {} } }, result: { appVisible: { content: [] }, isError: false, modelVisible: {} }, session: { binding: stable, connection: { capabilities: { tools: {} }, protocolEra: 'modern', protocolVersion: '2026-01-26', server: { name: 'weather', version: '1.0.0' } }, state: 'ready' } }; };",
+    "const runtimePreviewFor = (suffix) => { const generation = 'generation-' + suffix; const source = 'source-' + suffix; const sessionId = 'runtime-session-' + suffix; const bindingId = 'runtime-binding-' + suffix; const binding = { definitionDigest: 'definition-' + suffix, evidence: 'simulated', id: bindingId, profileId: 'portable', profileVersion: 'agent-bundle:mcp-apps:2026-01-26', registryRevision: 3, runVector: { runtimeGenerationId: generation, sourceRevision: source, stateVersion: suffix === 'a' ? 1 : 2 }, serverDigest: 'server-' + suffix, serverName: 'weather', sessionId, sessionRevision: suffix === 'a' ? 2 : 3, target: 'weather', transportDigest: 'transport-' + suffix }; const stable = { definitionDigest: binding.definitionDigest, registryRevision: binding.registryRevision, serverDigest: binding.serverDigest, serverName: binding.serverName, sessionId: binding.sessionId, sessionRevision: binding.sessionRevision, target: binding.target, transportDigest: binding.transportDigest }; const metadata = { extensions: { claude: { nativeHooks: 'native-hooks-must-stay-hidden', opaque: 'opaque-value-must-stay-hidden', root: '/private/workspace/agent-bundle.config.ts' }, openai: { opaque: 'unregistered-openai-must-stay-hidden' } }, provenance: {}, raw: {}, standard: {} }; const configExtensions = { entries: [{ configured: true, id: 'extension:claude', key: 'claude', provenance: { kind: 'config', sourcePath: 'agent-bundle.config.ts' }, target: 'claude' }, { configured: true, id: 'extension:codex', key: 'codex', provenance: { kind: 'config', sourcePath: 'agent-bundle.config.ts' }, target: 'codex' }, { configured: true, id: 'extension:portable', key: 'portable', provenance: { kind: 'config', sourcePath: 'agent-bundle.config.ts' }, target: 'portable' }], sourceRevision: source }; return { binding, clientSurface: { bootstrapUrl: runtimeBootstrapUrl, origin: new URL(runtimeBootstrapUrl).origin }, documentPolicy: initialRuntimePolicy(), kind: 'apps', metadata: { resource: metadata, result: metadata, tool: metadata }, operations: [], profile: { bootstrap: { kind: 'none' }, configExtensions, descriptor: { claimsRealHostParity: false, evidence: 'simulated', id: 'portable', label: 'Portable MCP Apps', version: 'agent-bundle:mcp-apps:2026-01-26' }, hostContext: { availableDisplayModes: ['inline'], containerDimensions: { height: 720, width: 1024 }, deviceCapabilities: {}, displayMode: 'inline', locale: 'en-US', platform: 'web', safeAreaInsets: { bottom: 0, left: 0, right: 0, top: 0 }, styles: {}, theme: 'light', timeZone: 'UTC', toolInfo: {}, userAgent: 'agent-bundle-runtime-mcp-app/1' }, kind: 'apps', metadata, permissions: { camera: {} }, resourceUri: 'ui://weather/app.html', warnings: [] }, resource: { html: '<main>Weather</main>', permissions: { camera: {} } }, result: { appVisible: { content: [] }, isError: false, modelVisible: {} }, session: { binding: stable, connection: { capabilities: { tools: {} }, protocolVersion: '2026-01-26', server: { name: 'weather', version: '1.0.0' } }, state: 'ready' } }; };",
     "let runtimePreview; let runtimeOperationTraces = []; let operationSequence = 0; let heldCreate; let bridgeCloseFailures = 0; let backendCloseFailures = 0; let unregisterThrows = 0; let currentHandle; let suspendedTransition; const runtimeEvents = []; const runtimeIframes = new Set(); const runtimeTrace = [];",
     "const originalSetAttribute = Element.prototype.setAttribute; Element.prototype.setAttribute = function(name, value) { if (this instanceof HTMLIFrameElement && ['allow', 'referrerpolicy', 'sandbox', 'src'].includes(name)) runtimeTrace.push({ name, value: String(value) }); return originalSetAttribute.call(this, name, value); };",
     "const observer = new MutationObserver((records) => { for (const record of records) for (const node of record.addedNodes) { if (node instanceof HTMLIFrameElement) runtimeIframes.add(node); if (node instanceof Element) node.querySelectorAll('iframe').forEach((frame) => runtimeIframes.add(frame)); } }); observer.observe(document.documentElement, { childList: true, subtree: true });",
diff --git a/packages/workbench/tests/mcp-app-preview.test.ts b/packages/workbench/tests/mcp-app-preview.test.ts
index 8ad24d050..dc958e443 100644
--- a/packages/workbench/tests/mcp-app-preview.test.ts
+++ b/packages/workbench/tests/mcp-app-preview.test.ts
@@ -162,7 +162,7 @@ const runtimePreview = Object.freeze({
   result: Object.freeze({ appVisible: Object.freeze({}), isError: false, modelVisible: Object.freeze({}) }),
   session: Object.freeze({
     binding: Object.freeze({ definitionDigest: 'definition-weather', registryRevision: 3, serverDigest: 'server-weather', serverName: 'weather', sessionId: 'runtime-session-weather', sessionRevision: 2, target: 'weather', transportDigest: 'transport-weather' }),
-    connection: Object.freeze({ capabilities: Object.freeze({ resources: Object.freeze({}), tools: Object.freeze({}) }), protocolEra: 'modern' as const, protocolVersion: '2026-01-26', server: Object.freeze({ name: 'weather', version: '1.0.0' }) }),
+    connection: Object.freeze({ capabilities: Object.freeze({ resources: Object.freeze({}), tools: Object.freeze({}) }), protocolVersion: '2026-01-26', server: Object.freeze({ name: 'weather', version: '1.0.0' }) }),
     state: 'ready' as const,
   }),
 }) as unknown as McpAppPreviewAppsSnapshot;
diff --git a/packages/workbench/tests/mcp-page-app-browser.test.ts b/packages/workbench/tests/mcp-page-app-browser.test.ts
index bd60a2eba..a46209887 100644
--- a/packages/workbench/tests/mcp-page-app-browser.test.ts
+++ b/packages/workbench/tests/mcp-page-app-browser.test.ts
@@ -133,7 +133,7 @@ const mountedPageFixture = async (mode: 'artifact' | 'runtime' | 'runtime-direct
       "const runtimeBinding = { definitionDigest: 'definition-runtime-weather', evidence: 'simulated', id: 'runtime-binding-weather', profileId: 'portable', profileVersion: 'agent-bundle:mcp-apps:2026-01-26', registryRevision: 4, runVector: { runtimeGenerationId: 'generation-runtime-weather', sourceRevision: 'source-runtime-weather', stateVersion: 1 }, serverDigest: 'server-runtime-weather', serverName: 'runtime-weather', sessionId: 'runtime-session-weather', sessionRevision: 2, target: 'portable', transportDigest: 'transport-runtime-weather' };",
       "const runtimeStableBinding = { definitionDigest: runtimeBinding.definitionDigest, registryRevision: runtimeBinding.registryRevision, serverDigest: runtimeBinding.serverDigest, serverName: runtimeBinding.serverName, sessionId: runtimeBinding.sessionId, sessionRevision: runtimeBinding.sessionRevision, target: runtimeBinding.target, transportDigest: runtimeBinding.transportDigest };",
       "const runtimeMetadata = { extensions: { claude: {}, openai: {} }, provenance: {}, raw: {}, standard: {} };",
-      "const runtimeResponseBinding = { ...runtimeStableBinding }; const runtimePreview = { binding: runtimeBinding, clientSurface: { bootstrapUrl: runtimeBootstrapUrl, origin: new URL(runtimeBootstrapUrl).origin }, documentPolicy: runtimePolicy, kind: 'apps', metadata: { resource: runtimeMetadata, result: runtimeMetadata, tool: runtimeMetadata }, operations: [], profile: { bootstrap: { kind: 'none' }, configExtensions: { entries: [], sourceRevision: 'source-runtime-weather' }, descriptor: { claimsRealHostParity: false, evidence: 'simulated', id: 'portable', label: 'Portable MCP Apps', version: 'agent-bundle:mcp-apps:2026-01-26' }, hostContext: { availableDisplayModes: ['inline'], containerDimensions: { height: 720, width: 1024 }, deviceCapabilities: {}, displayMode: 'inline', locale: 'en-US', platform: 'web', safeAreaInsets: { bottom: 0, left: 0, right: 0, top: 0 }, styles: {}, theme: 'light', timeZone: 'UTC', toolInfo: {}, userAgent: 'agent-bundle-runtime-mcp-app/1' }, kind: 'apps', metadata: runtimeMetadata, permissions: {}, resourceUri: 'ui://weather/runtime.html', warnings: [] }, resource: { html: '<main>Runtime weather</main>', permissions: {} }, result: { appVisible: { content: [] }, isError: false, modelVisible: {} }, session: { binding: runtimeResponseBinding, connection: { capabilities: { tools: {} }, protocolEra: 'modern', protocolVersion: '2026-01-26', server: { name: 'runtime-weather', version: '1.0.0' } }, state: 'ready' } };",
+      "const runtimeResponseBinding = { ...runtimeStableBinding }; const runtimePreview = { binding: runtimeBinding, clientSurface: { bootstrapUrl: runtimeBootstrapUrl, origin: new URL(runtimeBootstrapUrl).origin }, documentPolicy: runtimePolicy, kind: 'apps', metadata: { resource: runtimeMetadata, result: runtimeMetadata, tool: runtimeMetadata }, operations: [], profile: { bootstrap: { kind: 'none' }, configExtensions: { entries: [], sourceRevision: 'source-runtime-weather' }, descriptor: { claimsRealHostParity: false, evidence: 'simulated', id: 'portable', label: 'Portable MCP Apps', version: 'agent-bundle:mcp-apps:2026-01-26' }, hostContext: { availableDisplayModes: ['inline'], containerDimensions: { height: 720, width: 1024 }, deviceCapabilities: {}, displayMode: 'inline', locale: 'en-US', platform: 'web', safeAreaInsets: { bottom: 0, left: 0, right: 0, top: 0 }, styles: {}, theme: 'light', timeZone: 'UTC', toolInfo: {}, userAgent: 'agent-bundle-runtime-mcp-app/1' }, kind: 'apps', metadata: runtimeMetadata, permissions: {}, resourceUri: 'ui://weather/runtime.html', warnings: [] }, resource: { html: '<main>Runtime weather</main>', permissions: {} }, result: { appVisible: { content: [] }, isError: false, modelVisible: {} }, session: { binding: runtimeResponseBinding, connection: { capabilities: { tools: {} }, protocolVersion: '2026-01-26', server: { name: 'runtime-weather', version: '1.0.0' } }, state: 'ready' } };",
       "const runtimeRun = { completedAt: '2026-08-16T00:00:01.000Z', id: 'runtime-run-weather', input: { city: 'Paris' }, result: { app: { mcpBinding: runtimeStableBinding, resourceUri: 'ui://weather/runtime.html', surfaceId: 'mcp.edit-weather' }, modelVisible: { temperature: 22 }, trace: [], tree: [] }, startedAt: '2026-08-16T00:00:00.000Z', status: 'succeeded', surfaceId: 'mcp.render-weather', target: 'portable', vector: { runtimeGenerationId: 'generation-runtime-weather', sourceRevision: 'source-runtime-weather', stateVersion: 1 } };",
       "const runtimeProfile = { claimsRealHostParity: false, evidence: 'simulated', id: 'portable', label: 'Portable MCP Apps', version: 'agent-bundle:mcp-apps:2026-01-26' }; const runtimeSurface = { fixtures: [], id: 'mcp.render-weather', kind: 'mcp-app', label: 'Runtime weather', readOnly: false, targets: ['portable'] };",
       "const runtimeEvents = []; let heldCreate = deferred(); let bridgeCloseFailures = 0; let backendCloseFailures = 0; let registeredPreviewClose; const foreground = new ForegroundRouteClient({ fetch: async (input, init) => { const path = new URL(String(input), location.origin).pathname; if (path === '/api/project/session') { runtimeEvents.push('bootstrap'); return response({ cookieName: 'agent-bundle-foreground-session-0123456789abcdef0123456789abcdef', instanceId: 'foreground-instance-a', origin: location.origin, token: 'foreground-secret' }); } if (path === '/api/runtime/apps' && init?.method === 'POST') { const request = JSON.parse(String(init?.body)); runtimeEvents.push('create:' + request.runId + ':' + request.profileId + ':' + request.expectedGenerationId); return heldCreate.promise; } if (path.startsWith('/api/runtime/apps/') && init?.method === 'DELETE') { const bindingId = decodeURIComponent(path.slice('/api/runtime/apps/'.length)); runtimeEvents.push('backend:' + bindingId); if (backendCloseFailures > 0) { backendCloseFailures -= 1; runtimeEvents.push('backend-failed:' + bindingId); throw new Error('runtime backend close failed'); } return response({ closed: true }); } throw new Error('Unexpected runtime fixture request ' + path); } }); const runtime = new McpAppClient({ foreground });",
diff --git a/packages/workbench/tests/mcp-session-controller.test.ts b/packages/workbench/tests/mcp-session-controller.test.ts
index 642f5dfbe..d4b26906a 100644
--- a/packages/workbench/tests/mcp-session-controller.test.ts
+++ b/packages/workbench/tests/mcp-session-controller.test.ts
@@ -15,7 +15,6 @@ import { McpRouteClientError, type McpRouteCatalog } from '../src/mcp/mcp-route-
 const binding = Object.freeze({ epochId: 'epoch-a', serverName: 'weather', target: 'portable' as const });
 const connection = Object.freeze({
   capabilities: { tools: {} },
-  protocolEra: 'modern' as const,
   protocolVersion: '2025-11-25',
   server: { name: 'weather-fixture', version: '1.0.0' },
 });
@@ -27,7 +26,6 @@ const runtimeSession = Object.freeze({
   }),
   connection: Object.freeze({
     capabilities: Object.freeze({ resources: Object.freeze({ listChanged: true }), tools: Object.freeze({ listChanged: true }) }),
-    protocolEra: 'modern' as const,
     protocolVersion: '2026-07-28',
     server: Object.freeze({ name: 'weather-runtime', version: '4.2.0' }),
   }),
@@ -67,7 +65,6 @@ const restartedRuntimeSession = Object.freeze({
   }),
   connection: Object.freeze({
     capabilities: Object.freeze({ resources: Object.freeze({ listChanged: true }), tools: Object.freeze({ listChanged: true }) }),
-    protocolEra: 'modern' as const,
     protocolVersion: '2026-02-09',
     server: Object.freeze({ name: 'weather-runtime-next', version: '5.0.0' }),
   }),
@@ -2071,7 +2068,6 @@ it('preserves binding, trace, and history through restart while refreshing conne
   let catalogCount = 0;
   const restarted = Object.freeze({
     capabilities: { prompts: {} },
-    protocolEra: 'modern' as const,
     protocolVersion: '2026-01-26',
     server: { name: 'weather-fixture', version: '2.0.0' },
   });