fix: prevent partial tool leaks and non-blocking dispose

- syncTools: on paginated listTools failure, unregister any tools already
  registered in the current sync before rethrowing (prevents orphans)
- Effect disposer: call client.close() directly without awaiting startup
  completion — aborts a hanging connect promptly on HMR/dispose

packages/mcp/mcp-client/src/index.ts

@@ -140,8 +140,9 @@ export function apply(ctx: Context, config: Config): void {
   }
 
   // Connect and set up tools. Errors during connect are logged, not thrown
-  // (the plugin simply has no tools registered).
-  const ready = (async () => {
+  // (the plugin simply has no tools registered). The IIFE is fire-and-forget;
+  // disposal closes the client directly without waiting for startup.
+  void (async () => {
     await client.connect(transport)
     await resync()
 
@@ -156,9 +157,10 @@ export function apply(ctx: Context, config: Config): void {
     ctx.logger.error(`mcp-client: failed to connect: ${String(error)}`)
   })
 
-  // Fiber disposal: close the client (triggers onclose → tools unregistered).
+  // Fiber disposal: close the client immediately (triggers onclose → tools
+  // unregistered). No `await ready` — if connect is still pending, close aborts
+  // it promptly rather than blocking until the SDK request times out.
   ctx.effect(() => async () => {
-    await ready
-    try { await client.close() } catch { /* transport already gone */ }
+    try { await client.close() } catch { /* transport already gone or never connected */ }
   }, 'mcp-client.connection')
 }

packages/mcp/mcp-client/src/tools.ts

@@ -43,27 +43,34 @@ export async function syncTools(
 
   const disposers: ToolDisposers = new Map()
 
-  let cursor: string | undefined
-  do {
-    const response = await client.listTools(cursor ? { cursor } : undefined)
-    for (const tool of response.tools) {
-      const registeredName = opts.toolPrefix + tool.name
-      const definition: ToolDefinition = {
-        name: registeredName,
-        description: tool.description ?? '',
-        parameters: tool.inputSchema,
-        execute: createExecutor(client, tool.name, opts),
+  try {
+    let cursor: string | undefined
+    do {
+      const response = await client.listTools(cursor ? { cursor } : undefined)
+      for (const tool of response.tools) {
+        const registeredName = opts.toolPrefix + tool.name
+        const definition: ToolDefinition = {
+          name: registeredName,
+          description: tool.description ?? '',
+          parameters: tool.inputSchema,
+          execute: createExecutor(client, tool.name, opts),
+        }
+        try {
+          const dispose = ctx.tools.register(definition)
+          disposers.set(registeredName, dispose)
+        } catch {
+          // Name conflict — another tool with this name is already registered.
+          ctx.logger.warn(`mcp-client: skipping tool "${registeredName}" (name conflict)`)
+        }
       }
-      try {
-        const dispose = ctx.tools.register(definition)
-        disposers.set(registeredName, dispose)
-      } catch {
-        // Name conflict — another tool with this name is already registered.
-        ctx.logger.warn(`mcp-client: skipping tool "${registeredName}" (name conflict)`)
-      }
-    }
-    cursor = response.nextCursor
-  } while (cursor)
+      cursor = response.nextCursor
+    } while (cursor)
+  } catch (error: unknown) {
+    // Partial failure (e.g. a later page of listTools failed): unregister any
+    // tools already registered in this sync to avoid orphaning them.
+    for (const dispose of disposers.values()) dispose()
+    throw error
+  }
 
   return disposers
 }