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).
+  // (the plugin simply has no tools registered). The IIFE is fire-and-forget;
-  const ready = (async () => {
+  // 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 or never connected */ }
-    try { await client.close() } catch { /* transport already gone */ }
   }, 'mcp-client.connection')
 }

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

@@ -43,6 +43,7 @@ export async function syncTools(
 
   const disposers: ToolDisposers = new Map()
 
+  try {
     let cursor: string | undefined
     do {
       const response = await client.listTools(cursor ? { cursor } : undefined)
@@ -64,6 +65,12 @@ export async function syncTools(
       }
       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
 }