diff --git a/mon-entreprise/source/sites/mon-entreprise.fr/middlewares/trackSimulatorActions.ts b/mon-entreprise/source/sites/mon-entreprise.fr/middlewares/trackSimulatorActions.ts
index df1e9e963..5039f2f38 100644
--- a/mon-entreprise/source/sites/mon-entreprise.fr/middlewares/trackSimulatorActions.ts
+++ b/mon-entreprise/source/sites/mon-entreprise.fr/middlewares/trackSimulatorActions.ts
@@ -7,14 +7,13 @@ export default (tracker: Tracker) => {
 		next(action)
 		const newState = getState()
 		if (action.type == 'STEP_ACTION' && action.name == 'fold') {
-			tracker.debouncedPush([
-				'trackEvent',
-				'Simulator::answer',
-				action.source,
-				action.step,
-				situationSelector(newState)[action.step as DottedName],
-			])
-
+			// tracker.debouncedPush([
+			// 	'trackEvent',
+			// 	'Simulator::answer',
+			// 	action.source,
+			// 	action.step,
+			// 	situationSelector(newState)[action.step as DottedName],
+			// ])
 			// TODO : add tracking in UI instead ?
 			// if (!currentQuestionSelector(newState)) {
 			// 	tracker.push([
diff --git a/publicodes/source/components/Explanation.tsx b/publicodes/source/components/Explanation.tsx
index c1a6ab729..283e3eec9 100644
--- a/publicodes/source/components/Explanation.tsx
+++ b/publicodes/source/components/Explanation.tsx
@@ -28,6 +28,9 @@ import UneDeCesConditions from './mecanisms/UneDeCesConditions'
 import UnePossibilité from './mecanisms/UnePossibilité'
 import Unité from './mecanisms/Unité'
 import Variations from './mecanisms/Variations'
+import { useContext } from 'react'
+import { EngineContext } from './contexts'
+import { InternalError } from '../error'
 
 const UIComponents = {
 	constant: ConstantNode,
@@ -66,9 +69,19 @@ const UIComponents = {
 
 export default function Explanation({ node }) {
 	const visualisationKind = node.visualisationKind || node.nodeKind
+	const engine = useContext(EngineContext)
+	if (!engine) {
+		throw new InternalError(node)
+	}
+
+	// On ne veut pas (pour l'instant) déclencher une évaluation juste pour
+	// l'affichage.
+	// A voir si cela doit évoluer...
+	const displayedNode = node.evaluationId ? engine.evaluateNode(node) : node
+
 	const Component = UIComponents[visualisationKind]
 	if (!Component) {
 		throw new Error(`Unknown visualisation: ${visualisationKind}`)
 	}
-	return <Component {...node} />
+	return <Component {...displayedNode} />
 }
diff --git a/publicodes/source/components/mecanisms/common.tsx b/publicodes/source/components/mecanisms/common.tsx
index 3ccb15fd1..b36f36381 100644
--- a/publicodes/source/components/mecanisms/common.tsx
+++ b/publicodes/source/components/mecanisms/common.tsx
@@ -289,19 +289,7 @@ export function Leaf(
 		!node.name.includes(' . ') &&
 		rule.virtualRule
 	) {
-		return (
-			<Explanation
-				node={
-					// Cette logique est un peu hacky car on accède à cache, qui
-					// est une structure interne de Engine. Seulement, on ne veut
-					// pas (pour l'instant) déclencher une évaluation juste pour
-					// l'affichage.
-
-					// A voir si cela doit évoluer...
-					engine?.cache[dottedName] ?? rule
-				}
-			/>
-		)
+		return <Explanation node={rule} />
 	}
 	return (
 		<div
diff --git a/publicodes/source/index.ts b/publicodes/source/index.ts
index 32952316f..9a11b7354 100644
--- a/publicodes/source/index.ts
+++ b/publicodes/source/index.ts
@@ -16,6 +16,7 @@ import { reduceAST, transformAST } from './AST'
 
 const emptyCache = () => ({
 	_meta: { contextRule: [] },
+	nodes: new Map(),
 })
 
 type Cache = {
@@ -31,6 +32,7 @@ type Cache = {
 		inRecalcul?: boolean
 		filter?: string
 	}
+	nodes: Map<ASTNode, EvaluatedNode>
 }
 
 export type EvaluationOptions = Partial<{
@@ -60,16 +62,10 @@ export default class Engine<Name extends string = string> {
 	parsedRules: ParsedRules<Name>
 	parsedSituation: Record<string, ASTNode> = {}
 	replacements: Record<string, Array<ReplacementRule>> = {}
-	cache: Cache
-
-	// A number that is incremented every time the situation changes, and is used
-	// for inline cache invalidation.
-	situationVersion = 0
+	cache: Cache = emptyCache()
 	private warnings: Array<string> = []
 
 	constructor(rules: string | Record<string, Rule> | ParsedRules<Name>) {
-		this.cache = emptyCache()
-		this.resetCache()
 		if (typeof rules === 'string') {
 			this.parsedRules = parsePublicodes(rules) as ParsedRules<Name>
 		}
@@ -88,7 +84,7 @@ export default class Engine<Name extends string = string> {
 		this.replacements = getReplacements(this.parsedRules)
 	}
 
-	private resetCache() {
+	resetCache() {
 		this.cache = emptyCache()
 	}
 
@@ -96,7 +92,6 @@ export default class Engine<Name extends string = string> {
 		situation: Partial<Record<Name, string | number | object | ASTNode>> = {}
 	) {
 		this.resetCache()
-		this.situationVersion++
 		this.parsedSituation = mapObjIndexed((value, key) => {
 			if (value && typeof value === 'object' && 'nodeKind' in value) {
 				return value as ASTNode
@@ -153,20 +148,19 @@ export default class Engine<Name extends string = string> {
 	}
 
 	evaluateNode<N extends ASTNode = ASTNode>(
-		node: N & { lastEvaluation?: number; res?: EvaluatedNode }
+		node: N & { evaluationId?: string }
 	): N & EvaluatedNode {
 		if (!node.nodeKind) {
 			throw Error('The provided node must have a "nodeKind" attribute')
 		} else if (!evaluationFunctions[node.nodeKind]) {
 			throw Error(`Unknown "nodeKind": ${node.nodeKind}`)
 		}
-
-		if (!node.res || node.lastEvaluation !== this.situationVersion) {
-			node.res = evaluationFunctions[node.nodeKind].call(this, node)
-			node.lastEvaluation = this.situationVersion
+		let result = this.cache.nodes.get(node)
+		if (result === undefined) {
+			result = evaluationFunctions[node.nodeKind].call(this, node)
 		}
-
-		return node.res!
+		this.cache.nodes.set(node, result!)
+		return result as N & EvaluatedNode
 	}
 }
 
diff --git a/publicodes/source/mecanisms/inversion.ts b/publicodes/source/mecanisms/inversion.ts
index 092968b7c..9c200211f 100644
--- a/publicodes/source/mecanisms/inversion.ts
+++ b/publicodes/source/mecanisms/inversion.ts
@@ -55,16 +55,15 @@ export const evaluateInversion: EvaluationFunction<'inversion'> = function (
 	const evaluatedInversionGoal = this.evaluateNode(inversionGoal)
 	const unit = 'unit' in node ? node.unit : evaluatedInversionGoal.unit
 
-	const originalCache = { ...this.cache }
+	const originalCache = this.cache
 	const originalSituation = { ...this.parsedSituation }
 	let inversionNumberOfIterations = 0
 	delete this.parsedSituation[inversionGoal.dottedName as string]
 	const evaluateWithValue = (n: number) => {
 		inversionNumberOfIterations++
-		this.cache = {
-			_meta: { ...originalCache._meta },
-		}
-		this.situationVersion++
+		this.resetCache()
+		this.cache._meta = { ...originalCache._meta }
+
 		this.parsedSituation[node.explanation.ruleToInverse] = {
 			unit: unit,
 			nodeKind: 'unité',
@@ -141,7 +140,6 @@ export const evaluateInversion: EvaluationFunction<'inversion'> = function (
 	// // Uncomment to display the two attempts and their result
 	// console.table([{ x: x1, y: y1 }, { x: x2, y: y2 }])
 	// console.log('iteration:', inversionNumberOfIterations)
-	this.situationVersion++
 	this.cache = originalCache
 	this.parsedSituation = originalSituation
 	return {
diff --git a/publicodes/source/mecanisms/recalcul.ts b/publicodes/source/mecanisms/recalcul.ts
index 74ff0ddcc..cafa9bcf4 100644
--- a/publicodes/source/mecanisms/recalcul.ts
+++ b/publicodes/source/mecanisms/recalcul.ts
@@ -32,13 +32,13 @@ const evaluateRecalcul: EvaluationFunction<'recalcul'> = function (node) {
 				serializeUnit(originRule.unit) !== serializeUnit(replacement.unit)
 		) as Array<[ReferenceNode & EvaluatedNode, EvaluatedNode]>
 
-	const originalCache = { ...this.cache }
+	const originalCache = this.cache
 	const originalSituation = { ...this.parsedSituation }
 	// Optimisation : no need for recalcul if situation is the same
 	const invalidateCache = Object.keys(amendedSituation).length > 0
 	if (invalidateCache) {
-		this.cache = { _meta: { ...this.cache._meta, inRecalcul: true } }
-		this.situationVersion++
+		this.resetCache()
+		this.cache._meta = { ...this.cache._meta, inRecalcul: true }
 	}
 
 	this.parsedSituation = {
@@ -59,7 +59,6 @@ const evaluateRecalcul: EvaluationFunction<'recalcul'> = function (node) {
 	this.parsedSituation = originalSituation
 	if (invalidateCache) {
 		this.cache = originalCache
-		this.situationVersion++
 	}
 	return {
 		...node,