diff --git a/package.json b/package.json
index 7a08b8f7e..5d83b71d8 100644
--- a/package.json
+++ b/package.json
@@ -8,10 +8,7 @@
 	"engines": {
 		"node": ">=8.10.0 <10.0.0"
 	},
-	"browserslist": [
-		"> 1% in FR",
-		"not ie < 11"
-	],
+	"browserslist": ["> 1% in FR", "not ie < 11"],
 	"dependencies": {
 		"@babel/core": "=7.0.0-beta.51",
 		"@babel/plugin-proposal-decorators": "=7.0.0-beta.51",
@@ -92,20 +89,29 @@
 		"yaml-loader": "^0.5.0"
 	},
 	"scripts": {
-		"pretest": "LIST=`git diff --name-only HEAD..HEAD^ | grep .*\\.js | grep -v json`; if [ \"$LIST\" ]; then eslint $LIST; fi && flow check",
+		"pretest":
+			"LIST=`git diff --name-only HEAD..HEAD^ | grep .*\\.js | grep -v json`; if [ \"$LIST\" ]; then eslint $LIST; fi && flow check",
 		"start": "node source/server.js",
 		"externalize": "node source/externalize.js",
 		"prepare": "flow-typed install",
 		"compile": "webpack --config source/webpack.prod.js",
-		"test": "mocha-webpack --webpack-config source/webpack.test.js --require source-map-support/register --include componentTestSetup.js --require test/helpers/browser.js  \"./{,!(node_modules)/**/}!(webpack).test.js\"",
-		"test-watch": "mocha-webpack --webpack-config source/webpack.test.js --require source-map-support/register --require test/helpers/browser.js \"test/**/*.test.js\" --watch",
-		"test-meca": "mocha-webpack --webpack-config source/webpack.test.js --require source-map-support/register --require test/helpers/browser.js test/mecanisms.test.js --watch",
-		"test-rules": "mocha-webpack --webpack-config source/webpack.test.js --require source-map-support/register --require test/helpers/browser.js test/real-rules.test.js --watch",
-		"test-inversions": "mocha-webpack --webpack-config source/webpack.test.js --require source-map-support/register --require test/helpers/browser.js \"test/inversion.test.js\" --watch",
-		"test-components": "mocha-webpack --webpack-config source/webpack.test.js --require source-map-support/register --include componentTestSetup.js --require test/helpers/browser.js \"source/components/**/*.test.js\" --watch",
+		"test":
+			"mocha-webpack --webpack-config source/webpack.test.js --require source-map-support/register --include componentTestSetup.js --require test/helpers/browser.js  \"./{,!(node_modules)/**/}!(webpack).test.js\"",
+		"test-watch":
+			"mocha-webpack --webpack-config source/webpack.test.js --require source-map-support/register --require test/helpers/browser.js \"test/**/*.test.js\" --watch",
+		"test-meca":
+			"mocha-webpack --webpack-config source/webpack.test.js --require source-map-support/register --require test/helpers/browser.js test/mecanisms.test.js --watch",
+		"test-rules":
+			"mocha-webpack --webpack-config source/webpack.test.js --require source-map-support/register --require test/helpers/browser.js test/real-rules.test.js --watch",
+		"test-inversions":
+			"mocha-webpack --webpack-config source/webpack.test.js --require source-map-support/register --require test/helpers/browser.js \"test/inversion.test.js\" --watch",
+		"test-components":
+			"mocha-webpack --webpack-config source/webpack.test.js --require source-map-support/register --include componentTestSetup.js --require test/helpers/browser.js \"source/components/**/*.test.js\" --watch",
 		"heroku-postbuild": "yarn install --production=false && yarn compile",
-		"eslint": "LIST=`git diff --cached --name-only HEAD | grep .*\\.js | grep -v json`; if [ \"$LIST\" ]; then eslint $LIST; fi",
-		"eslint-check": "eslint --print-config .eslintrc | eslint-config-prettier-check"
+		"eslint":
+			"LIST=`git diff --cached --name-only HEAD | grep .*\\.js | grep -v json`; if [ \"$LIST\" ]; then eslint $LIST; fi",
+		"eslint-check":
+			"eslint --print-config .eslintrc | eslint-config-prettier-check"
 	},
 	"devDependencies": {
 		"@babel/preset-flow": "^7.0.0-beta.51",
diff --git a/source/engine/rules.js b/source/engine/rules.js
index b6426ec5d..54fd708c7 100644
--- a/source/engine/rules.js
+++ b/source/engine/rules.js
@@ -187,9 +187,7 @@ export let nestedSituationToPathMap = situation => {
 	let rec = (o, currentPath) =>
 		typeof o === 'object'
 			? chain(([k, v]) => rec(v, [...currentPath, trim(k)]), toPairs(o))
-			: typeof o === 'string'
-				? [[currentPath.join(' . '), o]]
-				: new Error('oups, all leaf values were expected to be strings')
+			: [[currentPath.join(' . '), o + '']]
 
 	return fromPairs(rec(situation, []))
 }
diff --git a/source/i18n.js b/source/i18n.js
index 92ca9c3bf..dda5ef05f 100644
--- a/source/i18n.js
+++ b/source/i18n.js
@@ -4,14 +4,22 @@ import queryString from 'query-string'
 import { getIframeOption, parseDataAttributes } from './utils'
 import enTranslations from './locales/en.yaml'
 
+let getFromSessionStorage = where =>
+	typeof sessionStorage !== 'undefined' ? sessionStorage[where] : null
+
+let setToSessionStorage = (where, what) =>
+	typeof sessionStorage !== 'undefined' &&
+	do {
+		sessionStorage[where] = what
+	}
+
 let lang =
 	getIframeOption('lang') ||
 	queryString.parse(location.search)['lang'] ||
-	parseDataAttributes(sessionStorage['lang']) ||
+	parseDataAttributes(getFromSessionStorage('lang')) ||
 	'fr'
 
-sessionStorage['lang'] = lang
-
+setToSessionStorage('lang', lang)
 i18next.init(
 	{
 		debug: false,
diff --git a/source/reducers/reducers.js b/source/reducers/reducers.js
index 416ede9ea..534ec2a35 100644
--- a/source/reducers/reducers.js
+++ b/source/reducers/reducers.js
@@ -67,7 +67,8 @@ function conversationSteps(
 	if (type === 'RESET_SIMULATION') return { foldedSteps: [], unfolded: null }
 	if (type !== 'STEP_ACTION') return state
 
-	if (name === 'fold') return { foldedSteps: [...state.foldedSteps, step] }
+	if (name === 'fold')
+		return { foldedSteps: [...state.foldedSteps, step], unfoldedStep: null }
 	if (name === 'unfold') {
 		// if a step had already been unfolded, bring it back !
 		return {
diff --git a/source/selectors/analyseSelectors.js b/source/selectors/analyseSelectors.js
index 69f275097..73fa3fa3f 100644
--- a/source/selectors/analyseSelectors.js
+++ b/source/selectors/analyseSelectors.js
@@ -28,7 +28,7 @@ import {
 
 export let flatRulesSelector = createSelector(
 	state => state.lang,
-	state => state.rules,
+	(state, props) => props && props.rules,
 	(lang, rules) => rules || (lang === 'en' ? baseRulesEn : baseRulesFr)
 )
 
diff --git a/test/conversation.test.js b/test/conversation.test.js
new file mode 100644
index 000000000..31cc3ac55
--- /dev/null
+++ b/test/conversation.test.js
@@ -0,0 +1,136 @@
+import { expect } from 'chai'
+import dedent from 'dedent-js'
+import yaml from 'js-yaml'
+import { enrichRule } from '../source/engine/rules'
+import reducers from '../source/reducers/reducers'
+import { currentQuestionSelector } from '../source/selectors/analyseSelectors'
+import { merge, assocPath } from 'ramda'
+
+let baseState = {
+	conversationSteps: { foldedSteps: [] },
+	form: { conversation: { values: {} } }
+}
+
+describe('conversation', function() {
+	it('should start with the first missing variable', function() {
+		let rawRules = [
+				// TODO - this won't work without the indirection, figure out why
+				{ nom: 'startHere', formule: { somme: ['a', 'b'] }, espace: 'top' },
+				{ nom: 'a', espace: 'top', formule: 'aa' },
+				{ nom: 'b', espace: 'top', formule: 'bb' },
+				{ nom: 'aa', question: '?', titre: 'a', espace: 'top' },
+				{ nom: 'bb', question: '?', titre: 'b', espace: 'top' }
+			],
+			rules = rawRules.map(enrichRule),
+			state = merge(baseState, {
+				targetNames: ['startHere']
+			}),
+			currentQuestion = currentQuestionSelector(state, { rules })
+
+		expect(currentQuestion).to.equal('top . aa')
+	})
+	it('should deal with double unfold', function() {
+		let rawRules = [
+				// TODO - this won't work without the indirection, figure out why
+				{
+					nom: 'startHere',
+					formule: { somme: ['a', 'b', 'c'] },
+					espace: 'top'
+				},
+				{ nom: 'a', espace: 'top', formule: 'aa' },
+				{ nom: 'b', espace: 'top', formule: 'bb' },
+				{ nom: 'c', espace: 'top', formule: 'cc' },
+				{ nom: 'aa', question: '?', titre: 'a', espace: 'top' },
+				{ nom: 'bb', question: '?', titre: 'b', espace: 'top' },
+				{ nom: 'cc', question: '?', titre: 'c', espace: 'top' }
+			],
+			rules = rawRules.map(enrichRule)
+
+		let step1 = merge(baseState, {
+			targetNames: ['startHere']
+		})
+		let step2 = reducers(
+			assocPath(
+				['form', 'conversation', 'values'],
+				{ top: { aa: '1' } },
+				step1
+			),
+			{
+				type: 'STEP_ACTION',
+				name: 'fold',
+				step: 'top . aa'
+			}
+		)
+
+		let step3 = reducers(
+			assocPath(
+				['form', 'conversation', 'values'],
+				{ top: { bb: '1', aa: '1' } },
+				step2
+			),
+			{
+				type: 'STEP_ACTION',
+				name: 'fold',
+				step: 'top . bb'
+			}
+		)
+		let step4 = reducers(step3, {
+			type: 'STEP_ACTION',
+			name: 'unfold',
+			step: 'top . aa'
+		})
+		let lastStep = reducers(step4, {
+			type: 'STEP_ACTION',
+			name: 'unfold',
+			step: 'top . bb'
+		})
+
+		expect(currentQuestionSelector(lastStep, { rules })).to.equal('top . bb')
+		expect(lastStep.conversationSteps).to.have.property('foldedSteps')
+		expect(lastStep.conversationSteps.foldedSteps).to.have.lengthOf(1)
+		expect(lastStep.conversationSteps.foldedSteps[0]).to.equal('top . aa')
+	})
+
+	it('should first ask for questions without defaults, then those with defaults', function() {
+		let rawRules = dedent`
+        - nom: net
+          formule: brut - cotisation
+
+        - nom: brut
+          format: euro
+
+        - nom: cotisation
+          formule:
+            multiplication:
+              assiette: brut
+              variations:
+                - si: cadre
+                  taux: 77%
+                - si: ≠ cadre
+                  taux: 80%
+        - nom: cadre
+          par défaut: non
+      `,
+			rules = yaml.safeLoad(rawRules).map(enrichRule)
+
+		let step1 = merge(baseState, {
+			targetNames: ['net']
+		})
+
+		expect(currentQuestionSelector(step1, { rules })).to.equal('brut')
+
+		let step2 = reducers(
+			assocPath(['form', 'conversation', 'values', 'brut'], '2300', step1),
+			{
+				type: 'STEP_ACTION',
+				name: 'fold',
+				step: 'brut'
+			}
+		)
+
+		expect(step2.conversationSteps).to.have.property('foldedSteps')
+		expect(step2.conversationSteps.foldedSteps).to.have.lengthOf(1)
+		expect(step2.conversationSteps.foldedSteps[0]).to.equal('brut')
+		expect(currentQuestionSelector(step2, { rules })).to.equal('cadre')
+	})
+})