diff --git a/scripts/generate.js b/scripts/generate.js
index b48f575..003336d 100644
--- a/scripts/generate.js
+++ b/scripts/generate.js
@@ -42,7 +42,16 @@ async function main() {
   const zodSrc = await fs.readFile(zodPath, "utf8");
   await fs.writeFile(
     zodPath,
-    updateDocs(zodSrc.replace(`from "zod"`, `from "zod/v4"`)),
+    updateDocs(
+      zodSrc
+        .replace(`from "zod"`, `from "zod/v4"`)
+        // Weird type issue
+        .replaceAll(`"McpServerStdio"`, `"stdio"`)
+        .replaceAll(
+          "_meta: z.unknown().optional()",
+          "_meta: z.object().optional()",
+        ),
+    ),
   );
 
   const tsPath = "./src/schema/types.gen.ts";
@@ -50,10 +59,14 @@ async function main() {
   await fs.writeFile(
     tsPath,
     updateDocs(
-      tsSrc.replace(
-        `export type ClientOptions`,
-        `// eslint-disable-next-line @typescript-eslint/no-unused-vars\ntype ClientOptions`,
-      ),
+      tsSrc
+        .replace(
+          `export type ClientOptions`,
+          `// eslint-disable-next-line @typescript-eslint/no-unused-vars\ntype ClientOptions`,
+        )
+        // Weird type issue
+        .replaceAll(`"McpServerStdio"`, `"stdio"`)
+        .replaceAll(`_meta?: unknown`, `_meta?: { [key: string]: unknown }`),
     ),
   );
 
diff --git a/src/acp.ts b/src/acp.ts
index 4412a4f..7abacb9 100644
--- a/src/acp.ts
+++ b/src/acp.ts
@@ -1,7 +1,8 @@
 import { z } from "zod";
-import * as schema from "./schema";
+import * as schema from "./schema/index.js";
 import * as validate from "./schema/zod.gen.js";
-export * from "./schema";
+export type * from "./schema/types.gen.js";
+export * from "./schema/index.js";
 export * from "./stream.js";
 
 import type { Stream } from "./stream.js";
diff --git a/src/schema/types.gen.ts b/src/schema/types.gen.ts
index 0b521a8..ea1bccd 100644
--- a/src/schema/types.gen.ts
+++ b/src/schema/types.gen.ts
@@ -17,7 +17,7 @@ export type AgentCapabilities = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * Whether the agent supports `session/load`.
    */
@@ -88,7 +88,7 @@ export type Annotations = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   audience?: Array<Role> | null;
   lastModified?: string | null;
   priority?: number | null;
@@ -101,7 +101,7 @@ export type AudioContent = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   annotations?: Annotations | null;
   data: string;
   mimeType: string;
@@ -114,7 +114,7 @@ export type AuthMethod = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * Optional description providing more details about this authentication method.
    */
@@ -138,7 +138,7 @@ export type AuthenticateRequest = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * The ID of the authentication method to use.
    * Must be one of the methods advertised in the initialize response.
@@ -153,7 +153,7 @@ export type AuthenticateResponse = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
 };
 
 /**
@@ -163,7 +163,7 @@ export type AvailableCommand = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * Human-readable description of what the command does.
    */
@@ -190,7 +190,7 @@ export type AvailableCommandsUpdate = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * Commands the agent can execute
    */
@@ -204,7 +204,7 @@ export type BlobResourceContents = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   blob: string;
   mimeType?: string | null;
   uri: string;
@@ -219,7 +219,7 @@ export type CancelNotification = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * The ID of the session to cancel operations for.
    */
@@ -238,7 +238,7 @@ export type ClientCapabilities = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * File system capabilities supported by the client.
    * Determines which file operations the agent can request.
@@ -305,7 +305,7 @@ export type Content = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * The actual content block.
    */
@@ -352,7 +352,7 @@ export type ContentChunk = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * A single item of content
    */
@@ -366,7 +366,7 @@ export type CreateTerminalRequest = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * Array of command arguments.
    */
@@ -407,7 +407,7 @@ export type CreateTerminalResponse = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * The unique identifier for the created terminal.
    */
@@ -423,7 +423,7 @@ export type CurrentModeUpdate = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * The ID of the current mode
    */
@@ -441,7 +441,7 @@ export type Diff = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * The new content after modification.
    */
@@ -463,7 +463,7 @@ export type EmbeddedResource = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   annotations?: Annotations | null;
   resource: EmbeddedResourceResource;
 };
@@ -482,7 +482,7 @@ export type EnvVariable = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * The name of the environment variable.
    */
@@ -556,7 +556,7 @@ export type FileSystemCapability = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * Whether the Client supports `fs/read_text_file` requests.
    */
@@ -574,7 +574,7 @@ export type HttpHeader = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * The name of the HTTP header.
    */
@@ -592,7 +592,7 @@ export type ImageContent = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   annotations?: Annotations | null;
   data: string;
   mimeType: string;
@@ -608,7 +608,7 @@ export type Implementation = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * Intended for programmatic or logical use, but can be used as a display
    * name fallback if title isn’t present.
@@ -639,7 +639,7 @@ export type InitializeRequest = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * Capabilities supported by the client.
    */
@@ -667,7 +667,7 @@ export type InitializeResponse = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * Capabilities supported by the agent.
    */
@@ -698,7 +698,7 @@ export type KillTerminalCommandRequest = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * The session ID for this request.
    */
@@ -716,7 +716,7 @@ export type KillTerminalCommandResponse = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
 };
 
 /**
@@ -734,7 +734,7 @@ export type ListSessionsRequest = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * Opaque cursor token from a previous response's nextCursor field for cursor-based pagination
    */
@@ -758,7 +758,7 @@ export type ListSessionsResponse = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * Opaque cursor token. If present, pass this in the next request's cursor parameter
    * to fetch the next page. If absent, there are no more results.
@@ -781,7 +781,7 @@ export type LoadSessionRequest = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * The working directory for this session.
    */
@@ -803,7 +803,7 @@ export type LoadSessionResponse = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * **UNSTABLE**
    *
@@ -829,7 +829,7 @@ export type McpCapabilities = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * Agent supports [`McpServer::Http`].
    */
@@ -856,7 +856,7 @@ export type McpServer =
       type: "sse";
     })
   | ({
-      type?: "McpServerStdio";
+      type?: "stdio";
     } & McpServerStdio);
 
 /**
@@ -866,7 +866,7 @@ export type McpServerHttp = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * HTTP headers to set when making requests to the MCP server.
    */
@@ -888,7 +888,7 @@ export type McpServerSse = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * HTTP headers to set when making requests to the MCP server.
    */
@@ -910,7 +910,7 @@ export type McpServerStdio = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * Command-line arguments to pass to the MCP server.
    */
@@ -953,7 +953,7 @@ export type ModelInfo = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * Optional description of the model.
    */
@@ -977,7 +977,7 @@ export type NewSessionRequest = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * The working directory for this session. Must be an absolute path.
    */
@@ -997,7 +997,7 @@ export type NewSessionResponse = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * **UNSTABLE**
    *
@@ -1029,7 +1029,7 @@ export type PermissionOption = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * Hint about the nature of this permission option.
    */
@@ -1073,7 +1073,7 @@ export type Plan = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * The list of tasks to be accomplished.
    *
@@ -1094,7 +1094,7 @@ export type PlanEntry = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * Human-readable description of what this task aims to accomplish.
    */
@@ -1145,7 +1145,7 @@ export type PromptCapabilities = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * Agent supports [`ContentBlock::Audio`].
    */
@@ -1174,7 +1174,7 @@ export type PromptRequest = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * The blocks of content that compose the user's message.
    *
@@ -1206,7 +1206,7 @@ export type PromptResponse = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * Indicates why the agent stopped processing the turn.
    */
@@ -1230,7 +1230,7 @@ export type ReadTextFileRequest = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * Maximum number of lines to read.
    */
@@ -1256,7 +1256,7 @@ export type ReadTextFileResponse = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   content: string;
 };
 
@@ -1267,7 +1267,7 @@ export type ReleaseTerminalRequest = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * The session ID for this request.
    */
@@ -1285,7 +1285,7 @@ export type ReleaseTerminalResponse = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
 };
 
 /**
@@ -1323,7 +1323,7 @@ export type RequestPermissionRequest = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * Available permission options for the user to choose from.
    */
@@ -1345,7 +1345,7 @@ export type RequestPermissionResponse = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * The user's decision on the permission request.
    */
@@ -1359,7 +1359,7 @@ export type ResourceLink = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   annotations?: Annotations | null;
   description?: string | null;
   mimeType?: string | null;
@@ -1381,7 +1381,7 @@ export type SelectedPermissionOutcome = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * The ID of the option the user selected.
    */
@@ -1403,7 +1403,7 @@ export type SessionCapabilities = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * **UNSTABLE**
    *
@@ -1439,7 +1439,7 @@ export type SessionInfo = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * The working directory for this session. Must be an absolute path.
    */
@@ -1469,7 +1469,7 @@ export type SessionListCapabilities = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
 };
 
 /**
@@ -1481,7 +1481,7 @@ export type SessionMode = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   description?: string | null;
   id: SessionModeId;
   name: string;
@@ -1499,7 +1499,7 @@ export type SessionModeState = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * The set of modes that the Agent can operate in
    */
@@ -1523,7 +1523,7 @@ export type SessionModelState = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * The set of models that the Agent can use
    */
@@ -1545,7 +1545,7 @@ export type SessionNotification = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * The ID of the session this update pertains to.
    */
@@ -1596,7 +1596,7 @@ export type SetSessionModeRequest = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * The ID of the mode to set.
    */
@@ -1611,7 +1611,7 @@ export type SetSessionModeRequest = {
  * Response to `session/set_mode` method.
  */
 export type SetSessionModeResponse = {
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
 };
 
 /**
@@ -1627,7 +1627,7 @@ export type SetSessionModelRequest = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * The ID of the model to set.
    */
@@ -1651,7 +1651,7 @@ export type SetSessionModelResponse = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
 };
 
 /**
@@ -1677,7 +1677,7 @@ export type Terminal = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   terminalId: string;
 };
 
@@ -1688,7 +1688,7 @@ export type TerminalExitStatus = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * The process exit code (may be null if terminated by signal).
    */
@@ -1706,7 +1706,7 @@ export type TerminalOutputRequest = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * The session ID for this request.
    */
@@ -1724,7 +1724,7 @@ export type TerminalOutputResponse = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * Exit status if the command has completed.
    */
@@ -1746,7 +1746,7 @@ export type TextContent = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   annotations?: Annotations | null;
   text: string;
 };
@@ -1758,7 +1758,7 @@ export type TextResourceContents = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   mimeType?: string | null;
   text: string;
   uri: string;
@@ -1776,7 +1776,7 @@ export type ToolCall = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * Content produced by the tool call.
    */
@@ -1849,7 +1849,7 @@ export type ToolCallLocation = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * Optional line number within the file.
    */
@@ -1881,7 +1881,7 @@ export type ToolCallUpdate = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * Replace the content collection.
    */
@@ -1943,7 +1943,7 @@ export type UnstructuredCommandInput = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * A hint to display when the input hasn't been provided yet
    */
@@ -1957,7 +1957,7 @@ export type WaitForTerminalExitRequest = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * The session ID for this request.
    */
@@ -1975,7 +1975,7 @@ export type WaitForTerminalExitResponse = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * The process exit code (may be null if terminated by signal).
    */
@@ -1995,7 +1995,7 @@ export type WriteTextFileRequest = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
   /**
    * The text content to write to the file.
    */
@@ -2017,5 +2017,5 @@ export type WriteTextFileResponse = {
   /**
    * Extension point for implementations
    */
-  _meta?: unknown;
+  _meta?: { [key: string]: unknown };
 };
diff --git a/src/schema/zod.gen.ts b/src/schema/zod.gen.ts
index 1b0d2e4..43f2533 100644
--- a/src/schema/zod.gen.ts
+++ b/src/schema/zod.gen.ts
@@ -6,7 +6,7 @@ import { z } from "zod/v4";
  * Describes an available authentication method.
  */
 export const zAuthMethod = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   description: z.union([z.string(), z.null()]).optional(),
   id: z.string(),
   name: z.string(),
@@ -18,7 +18,7 @@ export const zAuthMethod = z.object({
  * Specifies which authentication method to use.
  */
 export const zAuthenticateRequest = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   methodId: z.string(),
 });
 
@@ -26,14 +26,14 @@ export const zAuthenticateRequest = z.object({
  * Response to the `authenticate` method.
  */
 export const zAuthenticateResponse = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
 });
 
 /**
  * Binary resource contents.
  */
 export const zBlobResourceContents = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   blob: z.string(),
   mimeType: z.union([z.string(), z.null()]).optional(),
   uri: z.string(),
@@ -43,7 +43,7 @@ export const zBlobResourceContents = z.object({
  * Response containing the ID of the created terminal.
  */
 export const zCreateTerminalResponse = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   terminalId: z.string(),
 });
 
@@ -55,7 +55,7 @@ export const zCreateTerminalResponse = z.object({
  * See protocol docs: [Content](https://agentclientprotocol.com/protocol/tool-calls#content)
  */
 export const zDiff = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   newText: z.string(),
   oldText: z.union([z.string(), z.null()]).optional(),
   path: z.string(),
@@ -65,7 +65,7 @@ export const zDiff = z.object({
  * An environment variable to set when launching an MCP server.
  */
 export const zEnvVariable = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   name: z.string(),
   value: z.string(),
 });
@@ -118,7 +118,7 @@ export const zExtResponse = z.unknown();
  * See protocol docs: [FileSystem](https://agentclientprotocol.com/protocol/initialization#filesystem)
  */
 export const zFileSystemCapability = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   readTextFile: z.boolean().optional().default(false),
   writeTextFile: z.boolean().optional().default(false),
 });
@@ -132,7 +132,7 @@ export const zFileSystemCapability = z.object({
  * See protocol docs: [Client Capabilities](https://agentclientprotocol.com/protocol/initialization#client-capabilities)
  */
 export const zClientCapabilities = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   fs: zFileSystemCapability
     .optional()
     .default({ readTextFile: false, writeTextFile: false }),
@@ -143,7 +143,7 @@ export const zClientCapabilities = z.object({
  * An HTTP header to set when making requests to the MCP server.
  */
 export const zHttpHeader = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   name: z.string(),
   value: z.string(),
 });
@@ -154,7 +154,7 @@ export const zHttpHeader = z.object({
  * title for UI representation.
  */
 export const zImplementation = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   name: z.string(),
   title: z.union([z.string(), z.null()]).optional(),
   version: z.string(),
@@ -164,7 +164,7 @@ export const zImplementation = z.object({
  * Response to terminal/kill command method
  */
 export const zKillTerminalCommandResponse = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
 });
 
 /**
@@ -179,7 +179,7 @@ export const zKillTerminalCommandResponse = z.object({
  * @experimental
  */
 export const zListSessionsRequest = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   cursor: z.union([z.string(), z.null()]).optional(),
   cwd: z.union([z.string(), z.null()]).optional(),
 });
@@ -188,7 +188,7 @@ export const zListSessionsRequest = z.object({
  * MCP capabilities supported by the agent
  */
 export const zMcpCapabilities = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   http: z.boolean().optional().default(false),
   sse: z.boolean().optional().default(false),
 });
@@ -197,7 +197,7 @@ export const zMcpCapabilities = z.object({
  * HTTP transport configuration for MCP.
  */
 export const zMcpServerHttp = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   headers: z.array(zHttpHeader),
   name: z.string(),
   url: z.string(),
@@ -207,7 +207,7 @@ export const zMcpServerHttp = z.object({
  * SSE transport configuration for MCP.
  */
 export const zMcpServerSse = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   headers: z.array(zHttpHeader),
   name: z.string(),
   url: z.string(),
@@ -217,7 +217,7 @@ export const zMcpServerSse = z.object({
  * Stdio transport configuration for MCP.
  */
 export const zMcpServerStdio = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   args: z.array(z.string()),
   command: z.string(),
   env: z.array(zEnvVariable),
@@ -245,7 +245,7 @@ export const zMcpServer = z.union([
   ),
   z
     .object({
-      type: z.literal("McpServerStdio").optional(),
+      type: z.literal("stdio").optional(),
     })
     .and(zMcpServerStdio),
 ]);
@@ -271,7 +271,7 @@ export const zModelId = z.string();
  * @experimental
  */
 export const zModelInfo = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   description: z.union([z.string(), z.null()]).optional(),
   modelId: zModelId,
   name: z.string(),
@@ -283,7 +283,7 @@ export const zModelInfo = z.object({
  * See protocol docs: [Creating a Session](https://agentclientprotocol.com/protocol/session-setup#creating-a-session)
  */
 export const zNewSessionRequest = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   cwd: z.string(),
   mcpServers: z.array(zMcpServer),
 });
@@ -309,7 +309,7 @@ export const zPermissionOptionKind = z.union([
  * An option presented to the user when requesting permission.
  */
 export const zPermissionOption = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   kind: zPermissionOptionKind,
   name: z.string(),
   optionId: zPermissionOptionId,
@@ -348,7 +348,7 @@ export const zPlanEntryStatus = z.union([
  * See protocol docs: [Plan Entries](https://agentclientprotocol.com/protocol/agent-plan#plan-entries)
  */
 export const zPlanEntry = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   content: z.string(),
   priority: zPlanEntryPriority,
   status: zPlanEntryStatus,
@@ -364,7 +364,7 @@ export const zPlanEntry = z.object({
  * See protocol docs: [Agent Plan](https://agentclientprotocol.com/protocol/agent-plan)
  */
 export const zPlan = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   entries: z.array(zPlanEntry),
 });
 
@@ -383,7 +383,7 @@ export const zPlan = z.object({
  * See protocol docs: [Prompt Capabilities](https://agentclientprotocol.com/protocol/initialization#prompt-capabilities)
  */
 export const zPromptCapabilities = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   audio: z.boolean().optional().default(false),
   embeddedContext: z.boolean().optional().default(false),
   image: z.boolean().optional().default(false),
@@ -405,7 +405,7 @@ export const zProtocolVersion = z.number().int().gte(0).lte(65535);
  * See protocol docs: [Initialization](https://agentclientprotocol.com/protocol/initialization)
  */
 export const zInitializeRequest = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   clientCapabilities: zClientCapabilities.optional().default({
     fs: { readTextFile: false, writeTextFile: false },
     terminal: false,
@@ -418,7 +418,7 @@ export const zInitializeRequest = z.object({
  * Response containing the contents of a text file.
  */
 export const zReadTextFileResponse = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   content: z.string(),
 });
 
@@ -426,7 +426,7 @@ export const zReadTextFileResponse = z.object({
  * Response to terminal/release method
  */
 export const zReleaseTerminalResponse = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
 });
 
 /**
@@ -451,7 +451,7 @@ export const zRole = z.enum(["assistant", "user"]);
  * Optional annotations for the client. The client can use annotations to inform how objects are used or displayed
  */
 export const zAnnotations = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   audience: z.union([z.array(zRole), z.null()]).optional(),
   lastModified: z.union([z.string(), z.null()]).optional(),
   priority: z.union([z.number(), z.null()]).optional(),
@@ -461,7 +461,7 @@ export const zAnnotations = z.object({
  * Audio provided to or from an LLM.
  */
 export const zAudioContent = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   annotations: z.union([zAnnotations, z.null()]).optional(),
   data: z.string(),
   mimeType: z.string(),
@@ -471,7 +471,7 @@ export const zAudioContent = z.object({
  * An image provided to or from an LLM.
  */
 export const zImageContent = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   annotations: z.union([zAnnotations, z.null()]).optional(),
   data: z.string(),
   mimeType: z.string(),
@@ -482,7 +482,7 @@ export const zImageContent = z.object({
  * A resource that the server is capable of reading, included in a prompt or tool call result.
  */
 export const zResourceLink = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   annotations: z.union([zAnnotations, z.null()]).optional(),
   description: z.union([z.string(), z.null()]).optional(),
   mimeType: z.union([z.string(), z.null()]).optional(),
@@ -496,7 +496,7 @@ export const zResourceLink = z.object({
  * The user selected one of the provided options.
  */
 export const zSelectedPermissionOutcome = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   optionId: zPermissionOptionId,
 });
 
@@ -518,7 +518,7 @@ export const zRequestPermissionOutcome = z.union([
  * Response to a permission request.
  */
 export const zRequestPermissionResponse = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   outcome: zRequestPermissionOutcome,
 });
 
@@ -538,7 +538,7 @@ export const zSessionId = z.string();
  * See protocol docs: [Cancellation](https://agentclientprotocol.com/protocol/prompt-turn#cancellation)
  */
 export const zCancelNotification = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   sessionId: zSessionId,
 });
 
@@ -553,7 +553,7 @@ export const zClientNotification = z.object({
  * Request to create a new terminal and execute a command.
  */
 export const zCreateTerminalRequest = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   args: z.array(z.string()).optional(),
   command: z.string(),
   cwd: z.union([z.string(), z.null()]).optional(),
@@ -566,7 +566,7 @@ export const zCreateTerminalRequest = z.object({
  * Request to kill a terminal command without releasing the terminal.
  */
 export const zKillTerminalCommandRequest = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   sessionId: zSessionId,
   terminalId: z.string(),
 });
@@ -579,7 +579,7 @@ export const zKillTerminalCommandRequest = z.object({
  * See protocol docs: [Loading Sessions](https://agentclientprotocol.com/protocol/session-setup#loading-sessions)
  */
 export const zLoadSessionRequest = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   cwd: z.string(),
   mcpServers: z.array(zMcpServer),
   sessionId: zSessionId,
@@ -591,7 +591,7 @@ export const zLoadSessionRequest = z.object({
  * Only available if the client supports the `fs.readTextFile` capability.
  */
 export const zReadTextFileRequest = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   limit: z.union([z.number().int().gte(0), z.null()]).optional(),
   line: z.union([z.number().int().gte(0), z.null()]).optional(),
   path: z.string(),
@@ -602,7 +602,7 @@ export const zReadTextFileRequest = z.object({
  * Request to release a terminal and free its resources.
  */
 export const zReleaseTerminalRequest = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   sessionId: zSessionId,
   terminalId: z.string(),
 });
@@ -617,7 +617,7 @@ export const zReleaseTerminalRequest = z.object({
  * @experimental
  */
 export const zSessionInfo = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   cwd: z.string(),
   sessionId: zSessionId,
   title: z.union([z.string(), z.null()]).optional(),
@@ -634,7 +634,7 @@ export const zSessionInfo = z.object({
  * @experimental
  */
 export const zListSessionsResponse = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   nextCursor: z.union([z.string(), z.null()]).optional(),
   sessions: z.array(zSessionInfo),
 });
@@ -647,7 +647,7 @@ export const zListSessionsResponse = z.object({
  * Further capabilities can be added in the future for other means of filtering or searching the list.
  */
 export const zSessionListCapabilities = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
 });
 
 /**
@@ -662,7 +662,7 @@ export const zSessionListCapabilities = z.object({
  * See protocol docs: [Session Capabilities](https://agentclientprotocol.com/protocol/initialization#session-capabilities)
  */
 export const zSessionCapabilities = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   list: z.union([zSessionListCapabilities, z.null()]).optional(),
 });
 
@@ -675,7 +675,7 @@ export const zSessionCapabilities = z.object({
  * See protocol docs: [Agent Capabilities](https://agentclientprotocol.com/protocol/initialization#agent-capabilities)
  */
 export const zAgentCapabilities = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   loadSession: z.boolean().optional().default(false),
   mcpCapabilities: zMcpCapabilities
     .optional()
@@ -696,7 +696,7 @@ export const zAgentCapabilities = z.object({
  * See protocol docs: [Initialization](https://agentclientprotocol.com/protocol/initialization)
  */
 export const zInitializeResponse = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   agentCapabilities: zAgentCapabilities.optional().default({
     loadSession: false,
     mcpCapabilities: { http: false, sse: false },
@@ -723,7 +723,7 @@ export const zSessionModeId = z.string();
  * See protocol docs: [Session Modes](https://agentclientprotocol.com/protocol/session-modes)
  */
 export const zCurrentModeUpdate = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   currentModeId: zSessionModeId,
 });
 
@@ -733,7 +733,7 @@ export const zCurrentModeUpdate = z.object({
  * See protocol docs: [Session Modes](https://agentclientprotocol.com/protocol/session-modes)
  */
 export const zSessionMode = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   description: z.union([z.string(), z.null()]).optional(),
   id: zSessionModeId,
   name: z.string(),
@@ -743,7 +743,7 @@ export const zSessionMode = z.object({
  * The set of modes and the one currently active.
  */
 export const zSessionModeState = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   availableModes: z.array(zSessionMode),
   currentModeId: zSessionModeId,
 });
@@ -758,7 +758,7 @@ export const zSessionModeState = z.object({
  * @experimental
  */
 export const zSessionModelState = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   availableModels: z.array(zModelInfo),
   currentModelId: zModelId,
 });
@@ -767,7 +767,7 @@ export const zSessionModelState = z.object({
  * Response from loading an existing session.
  */
 export const zLoadSessionResponse = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   models: z.union([zSessionModelState, z.null()]).optional(),
   modes: z.union([zSessionModeState, z.null()]).optional(),
 });
@@ -778,7 +778,7 @@ export const zLoadSessionResponse = z.object({
  * See protocol docs: [Creating a Session](https://agentclientprotocol.com/protocol/session-setup#creating-a-session)
  */
 export const zNewSessionResponse = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   models: z.union([zSessionModelState, z.null()]).optional(),
   modes: z.union([zSessionModeState, z.null()]).optional(),
   sessionId: zSessionId,
@@ -788,7 +788,7 @@ export const zNewSessionResponse = z.object({
  * Request parameters for setting a session mode.
  */
 export const zSetSessionModeRequest = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   modeId: zSessionModeId,
   sessionId: zSessionId,
 });
@@ -797,7 +797,7 @@ export const zSetSessionModeRequest = z.object({
  * Response to `session/set_mode` method.
  */
 export const zSetSessionModeResponse = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
 });
 
 /**
@@ -810,7 +810,7 @@ export const zSetSessionModeResponse = z.object({
  * @experimental
  */
 export const zSetSessionModelRequest = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   modelId: zModelId,
   sessionId: zSessionId,
 });
@@ -825,7 +825,7 @@ export const zSetSessionModelRequest = z.object({
  * @experimental
  */
 export const zSetSessionModelResponse = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
 });
 
 /**
@@ -847,7 +847,7 @@ export const zStopReason = z.union([
  * See protocol docs: [Check for Completion](https://agentclientprotocol.com/protocol/prompt-turn#4-check-for-completion)
  */
 export const zPromptResponse = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   stopReason: zStopReason,
 });
 
@@ -880,7 +880,7 @@ export const zAgentResponse = z.union([
  * See protocol docs: [Terminal](https://agentclientprotocol.com/protocol/terminals)
  */
 export const zTerminal = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   terminalId: z.string(),
 });
 
@@ -888,7 +888,7 @@ export const zTerminal = z.object({
  * Exit status of a terminal command.
  */
 export const zTerminalExitStatus = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   exitCode: z.union([z.number().int().gte(0), z.null()]).optional(),
   signal: z.union([z.string(), z.null()]).optional(),
 });
@@ -897,7 +897,7 @@ export const zTerminalExitStatus = z.object({
  * Request to get the current output and status of a terminal.
  */
 export const zTerminalOutputRequest = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   sessionId: zSessionId,
   terminalId: z.string(),
 });
@@ -906,7 +906,7 @@ export const zTerminalOutputRequest = z.object({
  * Response containing the terminal output and exit status.
  */
 export const zTerminalOutputResponse = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   exitStatus: z.union([zTerminalExitStatus, z.null()]).optional(),
   output: z.string(),
   truncated: z.boolean(),
@@ -916,7 +916,7 @@ export const zTerminalOutputResponse = z.object({
  * Text provided to or from an LLM.
  */
 export const zTextContent = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   annotations: z.union([zAnnotations, z.null()]).optional(),
   text: z.string(),
 });
@@ -925,7 +925,7 @@ export const zTextContent = z.object({
  * Text-based resource contents.
  */
 export const zTextResourceContents = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   mimeType: z.union([z.string(), z.null()]).optional(),
   text: z.string(),
   uri: z.string(),
@@ -943,7 +943,7 @@ export const zEmbeddedResourceResource = z.union([
  * The contents of a resource, embedded into a prompt or tool call result.
  */
 export const zEmbeddedResource = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   annotations: z.union([zAnnotations, z.null()]).optional(),
   resource: zEmbeddedResourceResource,
 });
@@ -996,7 +996,7 @@ export const zContentBlock = z.union([
  * Standard content block (text, images, resources).
  */
 export const zContent = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   content: zContentBlock,
 });
 
@@ -1004,7 +1004,7 @@ export const zContent = z.object({
  * A streamed item of content
  */
 export const zContentChunk = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   content: zContentBlock,
 });
 
@@ -1016,7 +1016,7 @@ export const zContentChunk = z.object({
  * See protocol docs: [User Message](https://agentclientprotocol.com/protocol/prompt-turn#1-user-message)
  */
 export const zPromptRequest = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   prompt: z.array(zContentBlock),
   sessionId: zSessionId,
 });
@@ -1082,7 +1082,7 @@ export const zToolCallId = z.string();
  * See protocol docs: [Following the Agent](https://agentclientprotocol.com/protocol/tool-calls#following-the-agent)
  */
 export const zToolCallLocation = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   line: z.union([z.number().int().gte(0), z.null()]).optional(),
   path: z.string(),
 });
@@ -1131,7 +1131,7 @@ export const zToolKind = z.union([
  * See protocol docs: [Tool Calls](https://agentclientprotocol.com/protocol/tool-calls)
  */
 export const zToolCall = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   content: z.array(zToolCallContent).optional(),
   kind: zToolKind.optional(),
   locations: z.array(zToolCallLocation).optional(),
@@ -1151,7 +1151,7 @@ export const zToolCall = z.object({
  * See protocol docs: [Updating](https://agentclientprotocol.com/protocol/tool-calls#updating)
  */
 export const zToolCallUpdate = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   content: z.union([z.array(zToolCallContent), z.null()]).optional(),
   kind: z.union([zToolKind, z.null()]).optional(),
   locations: z.union([z.array(zToolCallLocation), z.null()]).optional(),
@@ -1170,7 +1170,7 @@ export const zToolCallUpdate = z.object({
  * See protocol docs: [Requesting Permission](https://agentclientprotocol.com/protocol/tool-calls#requesting-permission)
  */
 export const zRequestPermissionRequest = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   options: z.array(zPermissionOption),
   sessionId: zSessionId,
   toolCall: zToolCallUpdate,
@@ -1180,7 +1180,7 @@ export const zRequestPermissionRequest = z.object({
  * All text that was typed after the command name is provided as input.
  */
 export const zUnstructuredCommandInput = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   hint: z.string(),
 });
 
@@ -1193,7 +1193,7 @@ export const zAvailableCommandInput = zUnstructuredCommandInput;
  * Information about a command.
  */
 export const zAvailableCommand = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   description: z.string(),
   input: z.union([zAvailableCommandInput, z.null()]).optional(),
   name: z.string(),
@@ -1203,7 +1203,7 @@ export const zAvailableCommand = z.object({
  * Available commands are ready or have changed
  */
 export const zAvailableCommandsUpdate = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   availableCommands: z.array(zAvailableCommand),
 });
 
@@ -1265,7 +1265,7 @@ export const zSessionUpdate = z.union([
  * See protocol docs: [Agent Reports Output](https://agentclientprotocol.com/protocol/prompt-turn#3-agent-reports-output)
  */
 export const zSessionNotification = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   sessionId: zSessionId,
   update: zSessionUpdate,
 });
@@ -1281,7 +1281,7 @@ export const zAgentNotification = z.object({
  * Request to wait for a terminal command to exit.
  */
 export const zWaitForTerminalExitRequest = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   sessionId: zSessionId,
   terminalId: z.string(),
 });
@@ -1290,7 +1290,7 @@ export const zWaitForTerminalExitRequest = z.object({
  * Response containing the exit status of a terminal command.
  */
 export const zWaitForTerminalExitResponse = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   exitCode: z.union([z.number().int().gte(0), z.null()]).optional(),
   signal: z.union([z.string(), z.null()]).optional(),
 });
@@ -1301,7 +1301,7 @@ export const zWaitForTerminalExitResponse = z.object({
  * Only available if the client supports the `fs.writeTextFile` capability.
  */
 export const zWriteTextFileRequest = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
   content: z.string(),
   path: z.string(),
   sessionId: zSessionId,
@@ -1332,7 +1332,7 @@ export const zAgentRequest = z.object({
  * Response to `fs/write_text_file`
  */
 export const zWriteTextFileResponse = z.object({
-  _meta: z.unknown().optional(),
+  _meta: z.object().optional(),
 });
 
 export const zClientResponse = z.union([