v2 : moteurs purs complets + ambiances + persistance + seed Atelier du Canal

- engine/ : parametric (médiane basse, cristallisation, impact linear-share,
  bimodalité), state (canTransition 9 gardes doctrinales + windowOutcome),
  settings (resolveSettings + replis), triage (R-U→R6, phrases françaises),
  impact (concernés calculés), électionResult (blanc, quorum, égalité sans
  départage machine) — 296 tests vitest verts
- moods.css v2 : Source/Margelle/Nappe/Minuit (champ lexical du puits),
  tokens routes/états, socle borderless, print A4, tampon 井
- data/persistence.ts : IndexedDB local-first, export/import Bundle, lignée
- Seed Atelier du Canal (145 Ko, tous les états de l'UI) + test
- backend/scripts/export_seed_bundle.py (extraction Ğ1, bundle à générer)
- test anti-lexique (marqueur ld-v2)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/app/engine/impact.ts

@@ -0,0 +1,101 @@
+/**
+ * Perimeter engine — who is concerned by THIS decision.
+ *
+ * Pure functions — no store, no I/O. The store assembles the inputs and
+ * persists the result as Concern rows (origin 'computed').
+ *
+ * The computed union (BLUEPRINT-V2.md « Périmètres et inclusion ») :
+ *   members of the scoped circles ∪ persons named by the author
+ *   ∪ holders of active mandates whose domain intersects the scoped circles.
+ * Every inclusion carries its human-readable French reason — auditable in
+ * one tap, never « la machine t'a désigné ».
+ *
+ * MEMBERSHIP CHOICE (v2, documented): circle membership is NOMINATIVE per
+ * circle (Circle.memberIds is the ONLY membership rule). Circle nesting
+ * (parentCircleId, « couches d'oignon ») does NOT propagate membership:
+ * a parent circle does NOT automatically include the members of its child
+ * circles, nor the reverse. Nesting serves ONE gesture — widening the
+ * perimeter by one notch (« élargir d'un cran ») — which explicitly adds
+ * the parent circle to the scope; the computation never infers it.
+ */
+
+import type { Circle, Decision, Id, Mandate } from '~/types/domain'
+
+export interface ConcernedEntry {
+  personId: Id
+  /** French reason shown on tap (becomes Concern.reason). */
+  reason: string
+}
+
+/**
+ * Flatten circle ids into the set of their DIRECT nominative members.
+ *
+ * NON-PROPAGATION (see module header): only Circle.memberIds of the listed
+ * circles count. Members of child (or parent) circles are NOT included —
+ * widening is a scope gesture, never an automatic inference.
+ * Unknown circle ids are ignored (robustness over crash).
+ */
+export function expandCircleMembers(circleIds: Id[], circles: Circle[]): Set<Id> {
+  const members = new Set<Id>()
+  for (const circleId of circleIds) {
+    const circle = circles.find(c => c.id === circleId)
+    if (!circle) continue
+    for (const personId of circle.memberIds) members.add(personId)
+  }
+  return members
+}
+
+/**
+ * Compute the concerned persons of a decision scope, each with its reason.
+ *
+ * Deduplication: first reason wins, with source priority
+ * circle membership > named by author > mandate holder.
+ * The author is EXCLUDED from the list (they decide, they are not
+ * « concerned » by their own perimeter).
+ *
+ * Mandates count only when status 'active' and when their domain.circleIds
+ * INTERSECTS the scoped circles (any shared circle is enough — a mandate
+ * holder is concerned as soon as the decision touches their domain).
+ */
+export function computeConcerned(
+  scope: Decision['scope'],
+  circles: Circle[],
+  mandates: Mandate[],
+  authorId: Id,
+): ConcernedEntry[] {
+  // Map preserves insertion order; first reason wins (priority by pass order).
+  const concerned = new Map<Id, string>()
+
+  // 1. Members of the scoped circles (highest priority reason).
+  for (const circleId of scope.circleIds) {
+    const circle = circles.find(c => c.id === circleId)
+    if (!circle) continue
+    for (const personId of circle.memberIds) {
+      if (personId === authorId) continue
+      if (!concerned.has(personId)) {
+        concerned.set(personId, `membre du cercle ${circle.name}`)
+      }
+    }
+  }
+
+  // 2. Persons named by the author.
+  for (const personId of scope.personIds) {
+    if (personId === authorId) continue
+    if (!concerned.has(personId)) {
+      concerned.set(personId, 'nommé·e par l\'auteur')
+    }
+  }
+
+  // 3. Holders of active mandates whose domain intersects the scoped circles.
+  const scopedCircleIds = new Set(scope.circleIds)
+  for (const mandate of mandates) {
+    if (mandate.status !== 'active') continue
+    if (!mandate.domain.circleIds.some(id => scopedCircleIds.has(id))) continue
+    if (mandate.holderId === authorId) continue
+    if (!concerned.has(mandate.holderId)) {
+      concerned.set(mandate.holderId, `titulaire du mandat ${mandate.title}`)
+    }
+  }
+
+  return [...concerned].map(([personId, reason]) => ({ personId, reason }))
+}