fix(mcp): add type guards for MCP config override support

Add type guard functions to safely distinguish between full MCP configs
(local/remote) and override-only configs which only have the 'enabled' field.

- Add isFullMcpConfig, isLocalMcpConfig, isRemoteMcpConfig helpers
- Update MCP CLI commands to use type guards
- Update OAuth flow to use type guards
- Filter override configs when adding MCP servers via ACP

Fixes type errors introduced by McpOverrideConfig in the per-project
MCP config overrides feature.

Author: jknlsn

packages/opencode/src/acp/agent.ts

@@ -495,20 +495,24 @@ export namespace ACP {
       }
 
       await Promise.all(
-        Object.entries(mcpServers).map(async ([key, mcp]) => {
-          await this.sdk.mcp
-            .add(
-              {
-                directory,
-                name: key,
-                config: mcp,
-              },
-              { throwOnError: true },
-            )
-            .catch((error) => {
-              log.error("failed to add mcp server", { name: key, error })
-            })
-        }),
+        Object.entries(mcpServers)
+          .filter((entry): entry is [string, Config.McpLocalConfig | Config.McpRemoteConfig] =>
+            Config.isFullMcpConfig(entry[1]),
+          )
+          .map(async ([key, mcp]) => {
+            await this.sdk.mcp
+              .add(
+                {
+                  directory,
+                  name: key,
+                  config: mcp,
+                },
+                { throwOnError: true },
+              )
+              .catch((error) => {
+                log.error("failed to add mcp server", { name: key, error })
+              })
+          }),
       )
 
       setTimeout(() => {

packages/opencode/src/cli/cmd/mcp.ts

@@ -46,7 +46,7 @@ export const McpListCommand = cmd({
 
         for (const [name, serverConfig] of Object.entries(mcpServers)) {
           const status = statuses[name]
-          const hasOAuth = serverConfig.type === "remote" && !!serverConfig.oauth
+          const hasOAuth = Config.isRemoteMcpConfig(serverConfig) && !!serverConfig.oauth
           const hasStoredTokens = await MCP.hasStoredTokens(name)
 
           let statusIcon: string
@@ -78,7 +78,11 @@ export const McpListCommand = cmd({
             hint = "\n    " + status.error
           }
 
-          const typeHint = serverConfig.type === "remote" ? serverConfig.url : serverConfig.command.join(" ")
+          const typeHint = Config.isRemoteMcpConfig(serverConfig)
+            ? serverConfig.url
+            : Config.isLocalMcpConfig(serverConfig)
+              ? serverConfig.command.join(" ")
+              : "(override)"
           prompts.log.info(
             `${statusIcon} ${name} ${UI.Style.TEXT_DIM}${statusText}${hint}\n    ${UI.Style.TEXT_DIM}${typeHint}`,
           )
@@ -109,7 +113,9 @@ export const McpAuthCommand = cmd({
         const mcpServers = config.mcp ?? {}
 
         // Get OAuth-enabled servers
-        const oauthServers = Object.entries(mcpServers).filter(([_, cfg]) => cfg.type === "remote" && !!cfg.oauth)
+        const oauthServers = Object.entries(mcpServers).filter(
+          ([_, cfg]) => Config.isRemoteMcpConfig(cfg) && !!cfg.oauth,
+        )
 
         if (oauthServers.length === 0) {
           prompts.log.warn("No OAuth-enabled MCP servers configured")
@@ -135,7 +141,7 @@ export const McpAuthCommand = cmd({
             options: oauthServers.map(([name, cfg]) => ({
               label: name,
               value: name,
-              hint: cfg.type === "remote" ? cfg.url : undefined,
+              hint: Config.isRemoteMcpConfig(cfg) ? cfg.url : undefined,
             })),
           })
           if (prompts.isCancel(selected)) throw new UI.CancelledError()
@@ -149,7 +155,7 @@ export const McpAuthCommand = cmd({
           return
         }
 
-        if (serverConfig.type !== "remote" || !serverConfig.oauth) {
+        if (!Config.isRemoteMcpConfig(serverConfig) || !serverConfig.oauth) {
           prompts.log.error(`MCP server ${serverName} does not have OAuth configured`)
           prompts.outro("Done")
           return

packages/opencode/src/config/config.ts

@@ -379,6 +379,25 @@ export namespace Config {
   export const Mcp = z.union([z.discriminatedUnion("type", [McpLocal, McpRemote]), McpOverride])
   export type Mcp = z.infer<typeof Mcp>
 
+  export type McpLocalConfig = z.infer<typeof McpLocal>
+  export type McpRemoteConfig = z.infer<typeof McpRemote>
+  export type McpOverrideConfig = z.infer<typeof McpOverride>
+
+  /** Type guard to check if MCP config is a full config (local or remote) vs an override */
+  export function isFullMcpConfig(config: Mcp): config is McpLocalConfig | McpRemoteConfig {
+    return "type" in config
+  }
+
+  /** Type guard to check if MCP config is a local config */
+  export function isLocalMcpConfig(config: Mcp): config is McpLocalConfig {
+    return "type" in config && config.type === "local"
+  }
+
+  /** Type guard to check if MCP config is a remote config */
+  export function isRemoteMcpConfig(config: Mcp): config is McpRemoteConfig {
+    return "type" in config && config.type === "remote"
+  }
+
   export const Permission = z.enum(["ask", "allow", "deny"])
   export type Permission = z.infer<typeof Permission>
 

packages/opencode/src/mcp/index.ts

@@ -435,7 +435,7 @@ export namespace MCP {
       throw new Error(`MCP server not found: ${mcpName}`)
     }
 
-    if (mcpConfig.type !== "remote") {
+    if (!Config.isRemoteMcpConfig(mcpConfig)) {
       throw new Error(`MCP server ${mcpName} is not a remote server`)
     }
 
@@ -573,7 +573,7 @@ export namespace MCP {
   export async function supportsOAuth(mcpName: string): Promise<boolean> {
     const cfg = await Config.get()
     const mcpConfig = cfg.mcp?.[mcpName]
-    return mcpConfig?.type === "remote" && mcpConfig.oauth !== false
+    return !!mcpConfig && Config.isRemoteMcpConfig(mcpConfig) && mcpConfig.oauth !== false
   }
 
   /**