diff --git a/packages/web/src/components/SessionStateBadge.vue b/packages/web/src/components/SessionStateBadge.vue
index 40343b0..235eb6c 100644
--- a/packages/web/src/components/SessionStateBadge.vue
+++ b/packages/web/src/components/SessionStateBadge.vue
@@ -13,6 +13,7 @@
 import { computed } from 'vue';
 import { useI18n } from 'vue-i18n';
 import type { SessionSummary } from '@arboretum/shared';
+import { TONE_BADGE, TONE_DOT, activityTone, activityPulses } from '../lib/status-tokens';
 
 const props = defineProps<{ session: SessionSummary }>();
 const { t } = useI18n();
@@ -20,14 +21,7 @@ const { t } = useI18n();
 // activity (P3-B, managées) prime ; registryStatus (P2, découvertes) en repli.
 const activity = computed(() => props.session.activity ?? props.session.registryStatus ?? null);
 const label = computed(() => (activity.value ? t(`sessions.registryStatus.${activity.value}`) : t('sessions.live')));
-const badgeClass = computed(() => ({
-  'bg-amber-950 text-amber-300': activity.value === 'waiting',
-  'bg-sky-950 text-sky-300': activity.value === 'busy',
-  'bg-emerald-950 text-emerald-400': activity.value === 'idle' || activity.value === null,
-}));
-const dotClass = computed(() => ({
-  'bg-amber-300 animate-pulse': activity.value === 'waiting',
-  'bg-sky-300 animate-pulse': activity.value === 'busy',
-  'bg-emerald-400': activity.value === 'idle' || activity.value === null,
-}));
+const tone = computed(() => activityTone(activity.value));
+const badgeClass = computed(() => TONE_BADGE[tone.value]);
+const dotClass = computed(() => [TONE_DOT[tone.value], activityPulses(activity.value) ? 'animate-pulse' : '']);
 </script>
diff --git a/packages/web/src/components/TerminalCell.vue b/packages/web/src/components/TerminalCell.vue
index 6ea2c07..e90ecd4 100644
--- a/packages/web/src/components/TerminalCell.vue
+++ b/packages/web/src/components/TerminalCell.vue
@@ -1,6 +1,6 @@
 <template>
   <!-- focus-within → anneau visuel : montre quelle cellule reçoit la frappe clavier -->
-  <div class="flex min-h-0 flex-col overflow-hidden rounded-lg border border-zinc-800 bg-[#09090b] focus-within:ring-2 focus-within:ring-sky-600">
+  <div class="flex min-h-0 flex-col overflow-hidden rounded-lg border border-zinc-800 bg-surface-0 focus-within:ring-2 focus-within:ring-sky-600">
     <header class="flex items-center gap-2 border-b border-zinc-800 px-2 py-1">
       <SessionStateBadge :session="session" />
       <span class="truncate font-mono text-xs text-zinc-300" :title="session.cwd">{{ title }}</span>
diff --git a/packages/web/src/components/TerminalView.vue b/packages/web/src/components/TerminalView.vue
index f7bc497..fcd364a 100644
--- a/packages/web/src/components/TerminalView.vue
+++ b/packages/web/src/components/TerminalView.vue
@@ -1,5 +1,5 @@
 <template>
-  <div class="relative h-full min-h-0 bg-[#09090b]">
+  <div class="relative h-full min-h-0 bg-surface-0">
     <div ref="container" class="h-full w-full" />
     <div
       v-if="!controlling && !ended"
@@ -25,6 +25,7 @@ import { Terminal } from '@xterm/xterm';
 import { FitAddon } from '@xterm/addon-fit';
 import '@xterm/xterm/css/xterm.css';
 import { wsClient, type Attachment } from '../lib/ws-client';
+import { TERMINAL_THEME, TERMINAL_FONT_FAMILY } from '../lib/terminal-theme';
 
 const props = withDefaults(defineProps<{ sessionId: string; mode?: 'interactive' | 'observer' }>(), {
   mode: 'interactive',
@@ -48,14 +49,9 @@ onMounted(async () => {
   term = new Terminal({
     cursorBlink: true,
     fontSize: 13,
-    fontFamily: "ui-monospace, 'JetBrains Mono', 'Fira Code', Menlo, Consolas, monospace",
+    fontFamily: TERMINAL_FONT_FAMILY,
     scrollback: 20_000, // absorbe le replay élargi (REPLAY_TAIL_BYTES = 1 Mo) → on remonte plus loin
-    theme: {
-      background: '#09090b',
-      foreground: '#d4d4d8',
-      cursor: '#e4e4e7',
-      selectionBackground: '#3f3f46',
-    },
+    theme: TERMINAL_THEME,
   });
   const fit = new FitAddon();
   term.loadAddon(fit);
diff --git a/packages/web/src/components/ui/BaseBadge.vue b/packages/web/src/components/ui/BaseBadge.vue
index b2987c1..205a1ed 100644
--- a/packages/web/src/components/ui/BaseBadge.vue
+++ b/packages/web/src/components/ui/BaseBadge.vue
@@ -6,30 +6,15 @@
 </template>
 
 <script setup lang="ts">
-// Pastille d'état : centralise les paires bg/text répétées (zinc/emerald/amber/sky/red).
+// Pastille d'état : les paires bg/text et couleurs de point vivent dans lib/status-tokens
+// (partagées avec SessionStateBadge).
 import { computed } from 'vue';
-
-type Tone = 'zinc' | 'emerald' | 'amber' | 'sky' | 'red';
+import { TONE_BADGE, TONE_DOT, type Tone } from '../../lib/status-tokens';
 
 const props = withDefaults(defineProps<{ tone?: Tone; dot?: boolean; pulse?: boolean }>(), {
   tone: 'zinc',
 });
 
-const TONES: Record<Tone, string> = {
-  zinc: 'bg-zinc-800 text-zinc-400',
-  emerald: 'bg-emerald-950 text-emerald-400',
-  amber: 'bg-amber-950 text-amber-300',
-  sky: 'bg-sky-950 text-sky-300',
-  red: 'bg-red-950 text-red-400',
-};
-const DOTS: Record<Tone, string> = {
-  zinc: 'bg-zinc-500',
-  emerald: 'bg-emerald-400',
-  amber: 'bg-amber-300',
-  sky: 'bg-sky-300',
-  red: 'bg-red-400',
-};
-
-const toneClass = computed(() => TONES[props.tone]);
-const dotClass = computed(() => [DOTS[props.tone], props.pulse ? 'animate-pulse' : '']);
+const toneClass = computed(() => TONE_BADGE[props.tone]);
+const dotClass = computed(() => [TONE_DOT[props.tone], props.pulse ? 'animate-pulse' : '']);
 </script>
diff --git a/packages/web/src/components/ui/BaseButton.vue b/packages/web/src/components/ui/BaseButton.vue
index 9d206e9..d3313b6 100644
--- a/packages/web/src/components/ui/BaseButton.vue
+++ b/packages/web/src/components/ui/BaseButton.vue
@@ -43,12 +43,12 @@ const tag = computed(() => (asLink.value ? RouterLink : 'button'));
 const iconSize = computed(() => (props.size === 'sm' ? 15 : 16));
 
 const BASE =
-  'inline-flex items-center justify-center gap-1.5 rounded-lg font-medium transition-colors focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-offset-2 focus-visible:ring-offset-zinc-950 disabled:cursor-not-allowed disabled:opacity-50';
+  'inline-flex items-center justify-center gap-1.5 rounded-lg font-medium transition-colors focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-offset-2 focus-visible:ring-offset-surface-0 disabled:cursor-not-allowed disabled:opacity-50';
 
 const VARIANTS: Record<NonNullable<typeof props.variant>, string> = {
-  primary: 'bg-emerald-600 text-white hover:bg-emerald-500 focus-visible:ring-emerald-500/70',
-  secondary: 'border border-zinc-700 bg-zinc-800 text-zinc-200 hover:bg-zinc-700 focus-visible:ring-emerald-500/70',
-  ghost: 'text-zinc-300 hover:bg-zinc-800/60 focus-visible:ring-emerald-500/70',
+  primary: 'bg-accent text-white hover:bg-accent-hover focus-visible:ring-accent-hover/70',
+  secondary: 'border border-border-strong bg-surface-2 text-fg hover:bg-surface-3 focus-visible:ring-accent-hover/70',
+  ghost: 'text-zinc-300 hover:bg-surface-2/60 focus-visible:ring-accent-hover/70',
   danger: 'border border-red-900 bg-red-950 text-red-300 hover:bg-red-900 focus-visible:ring-red-500/70',
 };
 
diff --git a/packages/web/src/components/workspace/MonacoEditor.vue b/packages/web/src/components/workspace/MonacoEditor.vue
index e03dea4..2800706 100644
--- a/packages/web/src/components/workspace/MonacoEditor.vue
+++ b/packages/web/src/components/workspace/MonacoEditor.vue
@@ -57,7 +57,7 @@ onMounted(async () => {
   if (disposed || !host.value) return;
   editor.value = monaco.editor.create(host.value, {
     value: '',
-    theme: 'vs-dark',
+    theme: 'arboretum-dark',
     automaticLayout: true,
     minimap: { enabled: false },
     wordWrap: 'on',
diff --git a/packages/web/src/lib/monaco-setup.ts b/packages/web/src/lib/monaco-setup.ts
index 96182d3..01c786f 100644
--- a/packages/web/src/lib/monaco-setup.ts
+++ b/packages/web/src/lib/monaco-setup.ts
@@ -10,4 +10,15 @@ import EditorWorker from 'monaco-editor/esm/vs/editor/editor.worker?worker';
   getWorker: () => new EditorWorker(),
 };
 
+// Thème dérivé de vs-dark dont le fond s'aligne sur --color-surface-0 (#09090b) : cohérence
+// visuelle de l'éditeur avec le reste du chrome IDE. Défini une fois au chargement du module.
+monaco.editor.defineTheme('arboretum-dark', {
+  base: 'vs-dark',
+  inherit: true,
+  rules: [],
+  colors: {
+    'editor.background': '#09090b',
+  },
+});
+
 export { monaco };
diff --git a/packages/web/src/lib/status-tokens.ts b/packages/web/src/lib/status-tokens.ts
new file mode 100644
index 0000000..923fc3c
--- /dev/null
+++ b/packages/web/src/lib/status-tokens.ts
@@ -0,0 +1,38 @@
+// Tons de statut centralisés : paires bg/text et couleurs de point, partagées par
+// BaseBadge (pastille générique) et SessionStateBadge (état de session live).
+// Évite la duplication historique des classes amber/sky/emerald/zinc/red.
+
+export type Tone = 'zinc' | 'emerald' | 'amber' | 'sky' | 'red';
+
+/** Classe fond + texte de la pastille pour chaque ton. */
+export const TONE_BADGE: Record<Tone, string> = {
+  zinc: 'bg-zinc-800 text-zinc-400',
+  emerald: 'bg-emerald-950 text-emerald-400',
+  amber: 'bg-amber-950 text-amber-300',
+  sky: 'bg-sky-950 text-sky-300',
+  red: 'bg-red-950 text-red-400',
+};
+
+/** Classe de couleur du point d'état pour chaque ton. */
+export const TONE_DOT: Record<Tone, string> = {
+  zinc: 'bg-zinc-500',
+  emerald: 'bg-emerald-400',
+  amber: 'bg-amber-300',
+  sky: 'bg-sky-300',
+  red: 'bg-red-400',
+};
+
+/** Activité fine d'une session live (P3-B) : busy / waiting / idle (null = idle). */
+export type SessionActivityTone = 'busy' | 'waiting' | 'idle' | null;
+
+/** Mappe l'activité live d'une session vers un ton : waiting -> amber, busy -> sky, idle -> emerald. */
+export function activityTone(activity: SessionActivityTone): Tone {
+  if (activity === 'waiting') return 'amber';
+  if (activity === 'busy') return 'sky';
+  return 'emerald';
+}
+
+/** L'état busy/waiting mérite un point pulsé (activité en cours) ; idle reste fixe. */
+export function activityPulses(activity: SessionActivityTone): boolean {
+  return activity === 'waiting' || activity === 'busy';
+}
diff --git a/packages/web/src/lib/terminal-theme.ts b/packages/web/src/lib/terminal-theme.ts
new file mode 100644
index 0000000..c40c6dc
--- /dev/null
+++ b/packages/web/src/lib/terminal-theme.ts
@@ -0,0 +1,16 @@
+// Source unique du thème xterm. xterm exige des couleurs hex concrètes (pas de var CSS),
+// donc les valeurs vivent ici plutôt que dupliquées dans chaque composant terminal.
+// À garder synchronisé avec --color-surface-0 de style.css si la surface de base change.
+import type { ITheme } from '@xterm/xterm';
+
+// Aligne le fond sur --color-surface-0 (#09090b) ; fg = zinc-300, curseur = zinc-200,
+// sélection = zinc-700.
+export const TERMINAL_THEME: ITheme = {
+  background: '#09090b',
+  foreground: '#d4d4d8',
+  cursor: '#e4e4e7',
+  selectionBackground: '#3f3f46',
+};
+
+export const TERMINAL_FONT_FAMILY =
+  "ui-monospace, 'JetBrains Mono', 'Fira Code', Menlo, Consolas, monospace";
diff --git a/packages/web/src/style.css b/packages/web/src/style.css
index 80308b7..97d1123 100644
--- a/packages/web/src/style.css
+++ b/packages/web/src/style.css
@@ -1,9 +1,41 @@
 @import 'tailwindcss';
 
-/* Tokens additifs (la palette zinc/emerald/amber/sky/red reste celle de Tailwind). */
+/* Tokens de design centralisés.
+   Couche SÉMANTIQUE aliasant la palette Tailwind (zinc/emerald/amber/sky/red) : rendu
+   identique aujourd'hui, mais un point d'entrée unique pour la refonte IDE et un futur
+   thème clair (il suffirait de redéfinir ces variables sous [data-theme=light]). */
 @theme {
   --shadow-card: 0 1px 2px 0 rgb(0 0 0 / 0.4);
   --shadow-pop: 0 12px 32px -12px rgb(0 0 0 / 0.7);
+
+  /* Surfaces : du fond le plus profond de l'app aux surfaces survolées. */
+  --color-surface-0: var(--color-zinc-950); /* fond application (ex-#09090b) */
+  --color-surface-1: var(--color-zinc-900); /* cartes, panneaux */
+  --color-surface-2: var(--color-zinc-800); /* boutons, chips */
+  --color-surface-3: var(--color-zinc-700); /* survol des surfaces */
+
+  /* Bordures. */
+  --color-border: var(--color-zinc-800);
+  --color-border-strong: var(--color-zinc-700);
+
+  /* Texte. */
+  --color-fg: var(--color-zinc-200);
+  --color-fg-muted: var(--color-zinc-400);
+  --color-fg-subtle: var(--color-zinc-500);
+
+  /* Accent (interactions, focus). */
+  --color-accent: var(--color-emerald-600);
+  --color-accent-hover: var(--color-emerald-500);
+}
+
+/* Métriques du chrome IDE (barres, onglets, lignes). Consommées via des valeurs
+   arbitraires Tailwind, ex. h-[var(--ide-tab-h)]. */
+:root {
+  --ide-activitybar-w: 3rem;
+  --ide-titlebar-h: 2.25rem;
+  --ide-tab-h: 2.25rem;
+  --ide-statusbar-h: 1.5rem;
+  --ide-row-h: 1.75rem;
 }
 
 html,
@@ -13,13 +45,13 @@ body,
 }
 
 body {
-  background-color: var(--color-zinc-950);
-  color: var(--color-zinc-200);
+  background-color: var(--color-surface-0);
+  color: var(--color-fg);
   -webkit-font-smoothing: antialiased;
 }
 
 @layer base {
-  /* Tailwind v4 ne met plus cursor:pointer sur les boutons → on le rétablit
+  /* Tailwind v4 ne met plus cursor:pointer sur les boutons : on le rétablit
      (sauf désactivés, qui gardent le curseur par défaut / not-allowed). */
   button:not(:disabled),
   [role='button']:not([aria-disabled='true']) {
@@ -30,22 +62,22 @@ body {
 @layer components {
   /* Champs : rayon unifié + anneau de focus visible (absent auparavant). */
   .input {
-    @apply w-full rounded-lg border border-zinc-700 bg-zinc-950 px-2.5 py-1.5 text-sm text-zinc-100 outline-none transition-colors placeholder:text-zinc-600 focus-visible:border-zinc-500 focus-visible:ring-2 focus-visible:ring-emerald-500/40;
+    @apply w-full rounded-lg border border-border-strong bg-surface-0 px-2.5 py-1.5 text-sm text-zinc-100 outline-none transition-colors placeholder:text-zinc-600 focus-visible:border-zinc-500 focus-visible:ring-2 focus-visible:ring-accent-hover/40;
   }
 
   /* Boutons : socle CSS pour les usages hors composant (ex. RouterLink class="btn").
      Le composant BaseButton réplique ces variantes et ajoute tailles / loading / focus. */
   .btn {
-    @apply inline-flex items-center justify-center gap-1.5 rounded-lg border border-zinc-700 bg-zinc-800 px-3 py-1.5 text-sm font-medium text-zinc-200 transition-colors hover:bg-zinc-700 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-emerald-500/70 focus-visible:ring-offset-2 focus-visible:ring-offset-zinc-950 disabled:cursor-not-allowed disabled:opacity-50;
+    @apply inline-flex items-center justify-center gap-1.5 rounded-lg border border-border-strong bg-surface-2 px-3 py-1.5 text-sm font-medium text-fg transition-colors hover:bg-surface-3 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-accent-hover/70 focus-visible:ring-offset-2 focus-visible:ring-offset-surface-0 disabled:cursor-not-allowed disabled:opacity-50;
   }
   .btn-primary {
-    @apply inline-flex items-center justify-center gap-1.5 rounded-lg bg-emerald-600 px-3 py-1.5 text-sm font-medium text-white transition-colors hover:bg-emerald-500 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-emerald-500/70 focus-visible:ring-offset-2 focus-visible:ring-offset-zinc-950 disabled:cursor-not-allowed disabled:opacity-50;
+    @apply inline-flex items-center justify-center gap-1.5 rounded-lg bg-accent px-3 py-1.5 text-sm font-medium text-white transition-colors hover:bg-accent-hover focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-accent-hover/70 focus-visible:ring-offset-2 focus-visible:ring-offset-surface-0 disabled:cursor-not-allowed disabled:opacity-50;
   }
   .btn-danger {
-    @apply inline-flex items-center justify-center gap-1.5 rounded-lg border border-red-900 bg-red-950 px-3 py-1.5 text-sm font-medium text-red-300 transition-colors hover:bg-red-900 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-red-500/70 focus-visible:ring-offset-2 focus-visible:ring-offset-zinc-950 disabled:cursor-not-allowed disabled:opacity-50;
+    @apply inline-flex items-center justify-center gap-1.5 rounded-lg border border-red-900 bg-red-950 px-3 py-1.5 text-sm font-medium text-red-300 transition-colors hover:bg-red-900 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-red-500/70 focus-visible:ring-offset-2 focus-visible:ring-offset-surface-0 disabled:cursor-not-allowed disabled:opacity-50;
   }
   .btn-ghost {
-    @apply inline-flex items-center justify-center gap-1.5 rounded-lg px-3 py-1.5 text-sm font-medium text-zinc-300 transition-colors hover:bg-zinc-800/60 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-emerald-500/70 focus-visible:ring-offset-2 focus-visible:ring-offset-zinc-950 disabled:cursor-not-allowed disabled:opacity-50;
+    @apply inline-flex items-center justify-center gap-1.5 rounded-lg px-3 py-1.5 text-sm font-medium text-zinc-300 transition-colors hover:bg-surface-2/60 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-accent-hover/70 focus-visible:ring-offset-2 focus-visible:ring-offset-surface-0 disabled:cursor-not-allowed disabled:opacity-50;
   }
 
   .badge {
@@ -54,9 +86,9 @@ body {
 
   /* Cartes : factorise le motif répété dans les listes/sections/formulaires. */
   .card {
-    @apply rounded-xl border border-zinc-800 bg-zinc-900/50 p-3;
+    @apply rounded-xl border border-border bg-surface-1/50 p-3;
   }
   .card-inset {
-    @apply rounded-lg border border-zinc-800 bg-zinc-950/40 p-2;
+    @apply rounded-lg border border-border bg-surface-0/40 p-2;
   }
 }
diff --git a/packages/web/src/views/SessionView.vue b/packages/web/src/views/SessionView.vue
index 6f6b6e9..17bcea4 100644
--- a/packages/web/src/views/SessionView.vue
+++ b/packages/web/src/views/SessionView.vue
@@ -1,5 +1,5 @@
 <template>
-  <div ref="root" class="flex min-h-0 flex-1 flex-col bg-[#09090b]">
+  <div ref="root" class="flex min-h-0 flex-1 flex-col bg-surface-0">
     <header class="flex items-center gap-3 border-b border-zinc-800 bg-zinc-900/60 px-3 py-1.5">
       <RouterLink :to="{ name: 'sessions' }" class="text-sm text-zinc-400 transition-colors hover:text-zinc-200">
         ← {{ t('terminal.back') }}
diff --git a/packages/web/src/views/WorkspaceView.vue b/packages/web/src/views/WorkspaceView.vue
index 2d4690c..6147213 100644
--- a/packages/web/src/views/WorkspaceView.vue
+++ b/packages/web/src/views/WorkspaceView.vue
@@ -1,5 +1,5 @@
 <template>
-  <div class="flex h-dvh min-h-0 flex-col bg-[#09090b] text-zinc-200">
+  <div class="flex h-dvh min-h-0 flex-col bg-surface-0 text-fg">
     <!-- en-tête IDE -->
     <header class="flex items-center gap-3 border-b border-zinc-800 px-3 py-1.5">
       <BaseButton size="sm" variant="ghost" :icon="ChevronLeft" :to="{ name: 'dashboard' }">{{ t('common.back') }}</BaseButton>