fix(mcp): carry requestIdFormat through MCP config discovery

The option was only present on the transport-facing `MCPServerConfig`, so a
value written in `.omp/mcp.json` or a standalone `.mcp.json` never reached the
transports: discovery normalizes config into the canonical `MCPServer` shape and
`convertToLegacyConfig()` rebuilds the transport config from it, and neither step
knew about the field. Setting `"number"` in the documented config path silently
kept the snowflake-string default, which is the hang the option exists to avoid.

Wire it through the same four places `timeout` already uses: the canonical
`MCPServer` shape, the two OMP-native loaders (with validate-and-warn on an
unrecognized value), and the legacy conversion. Foreign-format providers are
untouched, since the key is OMP-specific.

Also point the `MCPServerConfigBase` doc comment at `RequestIdAllocator` rather
than a helper name that never existed.

packages/coding-agent/src/discovery/builtin.ts

@@ -23,6 +23,7 @@ import { type SlashCommand, slashCommandCapability } from "../capability/slash-c
 import { type SystemPrompt, systemPromptCapability } from "../capability/system-prompt";
 import { type CustomTool, toolCapability } from "../capability/tool";
 import type { LoadContext, LoadResult } from "../capability/types";
+import type { MCPRequestIdFormat } from "../mcp/types";
 import { expandTilde } from "../tools/path-utils";
 import {
 	buildRuleFromMarkdown,
@@ -154,10 +155,23 @@ async function loadMCPServers(ctx: LoadContext): Promise<LoadResult<MCPServer>>
 				timeout = undefined;
 			}
 
+			// Validate requestIdFormat: only the two documented encodings
+			let requestIdFormat: MCPRequestIdFormat | undefined;
+			if (serverConfig.requestIdFormat !== undefined && serverConfig.requestIdFormat !== null) {
+				if (serverConfig.requestIdFormat === "string" || serverConfig.requestIdFormat === "number") {
+					requestIdFormat = serverConfig.requestIdFormat;
+				} else {
+					logger.warn(
+						`MCP server "${serverName}": invalid requestIdFormat ${JSON.stringify(serverConfig.requestIdFormat)}, ignoring`,
+					);
+				}
+			}
+
 			result.push({
 				name: serverName,
 				enabled,
 				timeout,
+				requestIdFormat,
 				command: serverConfig.command as string | undefined,
 				args: serverConfig.args as string[] | undefined,
 				env: serverConfig.env as Record<string, string> | undefined,

packages/coding-agent/src/discovery/mcp-json.ts

@@ -26,6 +26,7 @@ interface MCPConfigFile {
 		{
 			enabled?: boolean;
 			timeout?: number;
+			requestIdFormat?: "string" | "number";
 			command?: string;
 			args?: string[];
 			env?: Record<string, string>;
@@ -83,10 +84,23 @@ function transformMCPConfig(config: MCPConfigFile, source: SourceMeta): MCPServe
 				}
 			}
 
+			let requestIdFormat: "string" | "number" | undefined;
+			if (serverConfig.requestIdFormat !== undefined) {
+				if (serverConfig.requestIdFormat === "string" || serverConfig.requestIdFormat === "number") {
+					requestIdFormat = serverConfig.requestIdFormat;
+				} else {
+					logger.warn("MCP server has invalid 'requestIdFormat' value, ignoring", {
+						name,
+						value: serverConfig.requestIdFormat,
+					});
+				}
+			}
+
 			const server: MCPServer = {
 				name,
 				enabled,
 				timeout,
+				requestIdFormat,
 				command: serverConfig.command,
 				args: serverConfig.args,
 				env: serverConfig.env,