stdlib: os package

Signed-off-by: Solomon Hykes <solomon@dagger.io>

stdlib/dagger/dagger.cue

@@ -1,16 +1,14 @@
 package dagger
 
 import (
-	"dagger.io/dagger/op"
 )
+// "dagger.io/dagger/op"
 
 // An artifact such as source code checkout, container image, binary archive...
 // May be passed as user input, or computed by a buildkit pipeline
-#Artifact: {
-	#up: [...op.#Op]
-	_
-	...
-}
+
+// FIXME (perf). See https://github.com/dagger/dagger/issues/445
+#Artifact: _
 
 // Secret value
 // FIXME: currently aliased as a string to mark secrets

stdlib/dagger/op/op.cue

@@ -48,7 +48,10 @@ package op
 	// `true` means also ignoring the mount cache volumes
 	always?: true | *false
 	dir:     string | *"/"
-	mount: [string]: "tmpfs" | "cache" | {from: _, path: string | *"/"}
+	// FIXME (perf): complex schema in low-level ops causes explosive perf issues
+	//    see https://github.com/dagger/dagger/issues/445
+	// mount: [string]: "tmpfs" | "cache" | {from: _, path: string | *"/"}
+	mount: [string]: _
 }
 
 #DockerLogin: {