diff --git a/Makefile b/Makefile
index 7bac6d6..1d8f71c 100755
--- a/Makefile
+++ b/Makefile
@@ -16,6 +16,7 @@ LOCAL_MODULES := \
 EXT_MODULES := \
 	$(wildcard node_modules/pouchdb/dist/*) \
 	$(wildcard node_modules/jszip/dist/*) \
+	$(wildcard node_modules/idb-keyval/dist/*.js) \
 	$(wildcard node_modules/showdown/dist/*)
 
 POUCH_DB := \
diff --git a/lib/types/Promise.js b/lib/types/Promise.js
index 215f51b..7614003 100755
--- a/lib/types/Promise.js
+++ b/lib/types/Promise.js
@@ -249,6 +249,15 @@ object.Constructor('IterablePromise', Promise, {
 			: (await Promise.all(list))
 				.flat() },
 
+	[Symbol.asyncIterator]: async function*(){
+		var list = this.__packed
+		if(list instanceof Promise){
+			yield this.__unpack(await list) 
+			return }
+		for await(var elem of list){
+			yield* elem instanceof Array ?
+				elem
+				: [elem] } },
 
 	// iterator methods...
 	//
diff --git a/lib/types/Set.js b/lib/types/Set.js
index 55d0c0e..68d148d 100755
--- a/lib/types/Set.js
+++ b/lib/types/Set.js
@@ -8,11 +8,29 @@
 /*********************************************************************/
 
 var object = require('ig-object')
+var stoppable = require('ig-stoppable')
 
 
 
 /*********************************************************************/
 
+// Wrap .map(..) / .filter(..) / .reduce(..) / .. to support STOP...
+// 
+// NOTE: internally these are implemented as for-of loops (./generator.js)
+var stoppableSet = function(iter){
+	return function(func){
+		return new Set([...this][iter](...arguments)) } }
+var stoppableValue = function(iter, no_return=false){
+	return function(func){
+		var res = [...this][iter](...arguments) 
+		return no_return ?
+			undefined
+			: res } }
+
+
+
+//---------------------------------------------------------------------
+
 var SetProtoMixin =
 module.SetProtoMixin =
 object.Mixin('SetMixin', 'soft', {
@@ -110,6 +128,12 @@ object.Mixin('SetMixin', 'soft', {
 		this.sort(order) 
 
 		return removed },
+
+	filter: stoppableSet('filter'),
+	map: stoppableSet('map'),
+	reduce: stoppableValue('reduce'),
+	reduceRight: stoppableValue('reduceRight'),
+	forEach: stoppableValue('map', true),
 })
 
 
diff --git a/lib/types/generator.js b/lib/types/generator.js
index 23cd3ab..5cf3084 100755
--- a/lib/types/generator.js
+++ b/lib/types/generator.js
@@ -189,11 +189,11 @@ var makeGenerator = function(name, pre){
 				].join('\n    ') }, }) } }
 
 // XXX do a better doc...
-var makePromise = function(name){
+var makeProxy = function(name){
 	return function(...args){
 		var that = this
 		return function(){
-			return that(...arguments)[name](func) } } }
+			return that(...arguments)[name](...args) } } }
 
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
@@ -267,9 +267,12 @@ object.Mixin('GeneratorMixin', 'soft', {
 
 	// promises...
 	//
-	then: makePromise('then'),
-	catch: makePromise('catch'),
-	finally: makePromise('finally'),
+	// NOTE: .then(..) and friends are intentionally not defined here to
+	// 		prevent control deadlocks when awaiting for a generator that
+	// 		expects manual unwinding e.g.:
+	// 			g = function*(){}
+	// 			await g				// will hang waiting for g to resolve
+	unwind: makeProxy('unwind'),
 
 	// combinators...
 	//
@@ -450,7 +453,8 @@ object.Mixin('GeneratorProtoMixin', 'soft', {
 
 	// promises...
 	//
-	then: function(onresolve, onreject){
+	// NOTE: this will unwind the generator...
+	unwind: function(onresolve, onreject){
 		var that = this
 		var p = new Promise(
 			function(resolve){
@@ -459,10 +463,12 @@ object.Mixin('GeneratorProtoMixin', 'soft', {
 			p.then(...arguments)
 			: p
 		return p },
+	then: function(...args){
+		return this.unwind(...args) },
 	catch: function(func){
-		return this.then().catch(func) },
+		return this.unwind().catch(...arguments) },
 	finally: function(func){
-		return this.then().finally(func) },
+		return this.unwind.finally(...arguments) },
 
 	// combinators...
 	//
@@ -531,22 +537,23 @@ object.Mixin('AsyncGeneratorProtoMixin', 'soft', {
 	//
 	// NOTE: this will unwind the generator...
 	// XXX create an iterator promise???
-	// XXX should we unwind???
-	then: function(resolve, reject){
+	unwind: function(onresolve, onreject){
 		var that = this
-		var p = new Promise(async function(_resolve, _reject){
+		var p = new Promise(async function(resolve){
 			var res = []
 			for await(var elem of that){
 				res.push(elem) }
-			_resolve(res) }) 
-		p = (resolve || reject) ?
+			resolve(res) }) 
+		p = (onresolve || onreject) ?
 			p.then(...arguments)
 			: p
 		return p },
+	then: function(...args){
+		return this.unwind(...args) },
 	catch: function(func){
-		return this.then().catch(func) },
-	finally: function(){
-		return this.then().finally(func) },
+		return this.unwind().catch(...arguments) },
+	finally: function(func){
+		return this.unwind.finally(...arguments) },
 
 	// XXX might be a good idea to use this approach above...
 	iter: stoppable(async function*(handler=undefined){
diff --git a/package.json b/package.json
index e326082..d1e1473 100755
--- a/package.json
+++ b/package.json
@@ -6,6 +6,7 @@
   "dependencies": {
     "@toast-ui/editor": "^3.2.0",
     "glob": "*",
+    "idb-keyval": "^6.2.0",
     "ig-actions": "*",
     "ig-features": "*",
     "ig-object": "*",
diff --git a/pwiki2.js b/pwiki2.js
index ad87b4a..e75aaeb 100755
--- a/pwiki2.js
+++ b/pwiki2.js
@@ -12,11 +12,14 @@
 * 		- images
 *
 *
+* XXX test: can we store the file handler with permissions in a ServiceWorker??
+* XXX store: add an indexedDB backend -- save on serialization...
+* 		- idb-keyval
+* 		- native???
 * XXX might be a good idea to wrap the wysiwig editor into a separate template
 * 		and use it in the main edit template to make it user-selectable...
 * XXX generalize html/dom api...
 * 		...see refresh() in pwiki2.html
-* XXX npx http-server ... -- for testing file access...
 * XXX test pouchdb latency at scale in browser...
 * XXX BUG: for some reason deleting and refreshing takes ~2x as long as 
 * 		refreshing...