diff --git a/CHANGELOG.md b/CHANGELOG.md
index 220da28..1f7360c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,7 +6,7 @@ Format basé sur [Keep a Changelog](https://keepachangelog.com/fr/1.1.0/),
 et [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 > **En cours de développement** : les changements à venir sont listés dans la section
-> [Unreleased](#unreleased). La dernière version livrée est **2.27.1**.
+> [Unreleased](#unreleased). La dernière version livrée est **2.27.2**.
 
 ---
 
@@ -14,6 +14,18 @@ et [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ---
 
+## [2.27.2] — 2026-09-26
+
+### Modifié
+
+- **#85 (T1) — extraction du domaine `health` hors du monolithe `backend/main.py`.**
+  `GET /api/health` et `GET /api/health/detailed` (admin) sont servis par le
+  nouveau `backend/routers/health.py` (monté dans `main.py`) et le modèle
+  `HealthResponse` déménage dans `backend/schemas.py` — chemins, réponses,
+  tags OpenAPI et authentification inchangés (aucun impact utilisateur).
+
+---
+
 ## [2.27.1] — 2026-09-26
 
 ### Modifié
diff --git a/README.fr.md b/README.fr.md
index 98cd017..635cf5f 100644
--- a/README.fr.md
+++ b/README.fr.md
@@ -4,7 +4,7 @@
 
 **Porte d'entrée web ultra-léger pour vos vaults Obsidian** — Accédez, naviguez et recherchez dans toutes vos notes Obsidian depuis n'importe quel appareil via une interface web moderne et responsive.
 
-[![Version](https://img.shields.io/badge/Version-2.27.1-blue.svg)]()
+[![Version](https://img.shields.io/badge/Version-2.27.2-blue.svg)]()
 [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
 [![Docker](https://img.shields.io/badge/Docker-Ready-blue.svg)](https://www.docker.com/)
 [![Python](https://img.shields.io/badge/Python-3.11+-green.svg)](https://www.python.org/)
@@ -976,8 +976,8 @@ Ce projet est sous licence **MIT** — voir le fichier [LICENSE](LICENSE) pour l
 
 ## 📝 Changelog
 
-Consultez le [CHANGELOG.md](./CHANGELOG.md) pour l'historique complet de toutes les versions (v1.0.0 → v2.27.1).
+Consultez le [CHANGELOG.md](./CHANGELOG.md) pour l'historique complet de toutes les versions (v1.0.0 → v2.27.2).
 
 ---
 
-*Projet : ObsiGate | Version : 2.27.1 | Dernière mise à jour : Septembre 2026*
+*Projet : ObsiGate | Version : 2.27.2 | Dernière mise à jour : Septembre 2026*
diff --git a/README.md b/README.md
index fdb2ecb..f7b2521 100644
--- a/README.md
+++ b/README.md
@@ -2,7 +2,7 @@
 
 **Ultra-light web gateway for your Obsidian vaults** — Access, browse, and search all your Obsidian notes from any device via a modern, responsive web interface.
 
-[![Version](https://img.shields.io/badge/Version-2.27.1-blue.svg)]()
+[![Version](https://img.shields.io/badge/Version-2.27.2-blue.svg)]()
 [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
 [![Docker](https://img.shields.io/badge/Docker-Ready-blue.svg)](https://www.docker.com/)
 [![Python](https://img.shields.io/badge/Python-3.11+-green.svg)](https://www.python.org/)
@@ -1151,8 +1151,8 @@ This project is licensed under the **MIT License** - see the [LICENSE](LICENSE)
 
 ## 📝 Changelog
 
-See [CHANGELOG.md](./CHANGELOG.md) for the complete version history (v1.0.0 → v2.27.1).
+See [CHANGELOG.md](./CHANGELOG.md) for the complete version history (v1.0.0 → v2.27.2).
 
 ---
 
-*Project: ObsiGate | Version: 2.27.1 | Last updated: September 2026*
+*Project: ObsiGate | Version: 2.27.2 | Last updated: September 2026*
diff --git a/VERSION b/VERSION
index f046523..05abc55 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.27.1
+2.27.2
diff --git a/backend/main.py b/backend/main.py
index a40dc06..b063989 100644
--- a/backend/main.py
+++ b/backend/main.py
@@ -398,19 +398,6 @@ class ReloadResponse(BaseModel):
     vaults: dict[str, Any] = Field(description="Per-vault file counts after reload")
 
 
-class HealthResponse(BaseModel):
-    """Application health status."""
-    status: str = Field(description="Health status ('ok' or 'error')")
-    version: str = Field(description="Application version (x.y.z — latest release tag)")
-    vaults: int = Field(description="Number of configured vaults")
-    total_files: int = Field(description="Total indexed files across all vaults")
-    total_tokens: int = Field(description="Total indexed tokens (approx.) across all vaults", default=0)
-    last_full_index_ts: str = Field(description="ISO timestamp of last full index rebuild", default="")
-    uptime_seconds: int = Field(description="Server uptime in seconds", default=0)
-    git_describe: str = Field(default="", description="Full git describe string (commits beyond tag), empty if no git")
-    git_commit: str = Field(default="", description="Short HEAD commit hash, empty if no git")
-
-
 class DirectoryCreateRequest(BaseModel):
     """Request to create a new directory."""
     path: str = Field(description="Relative path of the new directory")
@@ -867,7 +854,7 @@ async def lifespan(app: FastAPI):
     _search_executor = None
 
 
-from backend.version import get_git_commit, get_git_describe, get_version
+from backend.version import get_version
 
 app = FastAPI(
     title="ObsiGate API",
@@ -959,6 +946,7 @@ except Exception:  # pragma: no cover - WeasyPrint/GTK missing
 from backend.ai_routes import router as ai_router
 from backend.bookslm_routes import router as bookslm_router
 from backend.export import ExportError, export_epub, export_html, export_md_bundle
+from backend.routers.health import router as health_router
 from backend.saved_searches import delete_saved, get_saved, save_search
 from backend.share import (
     create_share,
@@ -981,6 +969,7 @@ app.include_router(auth_router)
 app.include_router(ai_router)
 app.include_router(bookslm_router)
 app.include_router(skills_router)
+app.include_router(health_router)  # ROADMAP #85 T1 — System / health
 
 # Admin Dashboard endpoints (system stats, audit logs, backups, stream)
 try:
@@ -1306,125 +1295,9 @@ def _render_markdown(raw_md: str, vault_name: str, current_file_path: Path | Non
 
 
 # ---------------------------------------------------------------------------
-# API Endpoints
+# API Endpoints — System / health : voir backend.routers.health (#85 T1)
 # ---------------------------------------------------------------------------
 
-@app.get("/api/health", response_model=HealthResponse)
-async def api_health():
-    """Health check endpoint for Docker and monitoring.
-
-    Returns:
-        Application status, version, vault count and total file count.
-    """
-    total_files = sum(len(v["files"]) for v in index.values())
-    total_tokens = sum(len(v.get("files", [])) * 1000 for v in index.values())  # rough approx
-    import time
-
-    from backend.indexer import _last_full_index_ts
-    uptime = int(time.time() - _SERVER_START_TIME) if '_SERVER_START_TIME' in globals() else 0
-    return {
-        "status": "ok",
-        "version": app.version,
-        "vaults": len(index),
-        "total_files": total_files,
-        "total_tokens": total_tokens,
-        "last_full_index_ts": _last_full_index_ts,
-        "uptime_seconds": uptime,
-        "git_describe": get_git_describe(),
-        "git_commit": get_git_commit(),
-    }
-
-
-@app.get("/api/health/detailed", response_model=HealthResponse)
-async def api_health_detailed(current_user=Depends(require_admin)):
-    """Detailed health check — admin only.
-
-    Returns enriched metrics including memory, disk, SSE connections, and backup stats.
-    """
-
-    import psutil
-
-    from backend.admin import _count_active_sessions, _get_disk_stats
-    from backend.indexer import _last_full_index_ts, index
-    
-    total_files = sum(len(v["files"]) for v in index.values())
-    total_tokens = sum(len(v.get("files", [])) * 1000 for v in index.values())
-    import time
-    uptime = int(time.time() - _SERVER_START_TIME) if '_SERVER_START_TIME' in globals() else 0
-    
-    # Memory
-    vm = psutil.virtual_memory()
-    mem_used_mb = round(vm.used / (1024 ** 2), 1)
-    mem_total_mb = round(vm.total / (1024 ** 2), 1)
-    mem_pct = round(vm.percent, 1)
-    
-    # CPU
-    cpu_pct = psutil.cpu_percent(interval=None)
-    
-    # Disk
-    disk_used_gb, disk_total_gb = _get_disk_stats()
-    disk_free_gb = round(disk_total_gb - disk_used_gb, 2)
-    disk_pct = round((disk_used_gb / disk_total_gb * 100) if disk_total_gb > 0 else 0, 1)
-    
-    # SSE connections (approximation)
-    active_sessions = _count_active_sessions()
-    
-    # Backups
-    from backend.admin import _scan_backups
-    backup_rows = _scan_backups()
-    total_backups = len(backup_rows)
-    total_backup_size_mb = round(sum(r["size"] for r in backup_rows) / (1024 ** 2), 2)
-    oldest_backup_age_days = 0.0
-    if backup_rows:
-        now_ts = int(time.time())
-        oldest_ts = min(r["timestamp"] for r in backup_rows)
-        oldest_backup_age_days = round((now_ts - oldest_ts) / 86400, 2)
-    
-    # Index details
-    index_detail = {}
-    for name, data in index.items():
-        index_detail[name] = {
-            "file_count": len(data["files"]),
-            "tag_count": len(data["tags"]),
-            "token_count_approx": len(data.get("files", [])) * 1000,
-        }
-    
-    return {
-        "status": "ok",
-        "version": app.version,
-        "vaults": len(index),
-        "total_files": total_files,
-        "total_tokens": total_tokens,
-        "last_full_index_ts": _last_full_index_ts,
-        "uptime_seconds": uptime,
-        "git_describe": get_git_describe(),
-        "git_commit": get_git_commit(),
-        # Enriched fields
-        "memory": {
-            "used_mb": mem_used_mb,
-            "total_mb": mem_total_mb,
-            "percent": mem_pct,
-        },
-        "cpu": {
-            "percent": cpu_pct,
-        },
-        "disk": {
-            "used_gb": disk_used_gb,
-            "total_gb": disk_total_gb,
-            "free_gb": disk_free_gb,
-            "percent": disk_pct,
-        },
-        "connections": {
-            "active_sse": active_sessions,
-        },
-        "backups": {
-            "total_count": total_backups,
-            "total_size_mb": total_backup_size_mb,
-            "oldest_age_days": oldest_backup_age_days,
-        },
-        "index": index_detail,
-    }
-
 
 @app.get("/api/vaults", response_model=list[VaultInfo])
 async def api_vaults(current_user=Depends(require_auth)):
diff --git a/backend/routers/__init__.py b/backend/routers/__init__.py
new file mode 100644
index 0000000..f1a4614
--- /dev/null
+++ b/backend/routers/__init__.py
@@ -0,0 +1,7 @@
+"""ObsiGate — routers FastAPI par domaine (ROADMAP #85).
+
+Découpage progressif du monolithe ``backend/main.py`` : chaque module de ce
+paquet expose un ``APIRouter`` monté par ``main.py``. Les handlers sont
+déplacés sans changement de comportement (mêmes chemins, mêmes modèles de
+réponse, mêmes dépendances d'authentification).
+"""
diff --git a/backend/routers/health.py b/backend/routers/health.py
new file mode 100644
index 0000000..d5a5779
--- /dev/null
+++ b/backend/routers/health.py
@@ -0,0 +1,143 @@
+"""System health endpoints (ROADMAP #85, tranche 1).
+
+Handlers déplacés depuis :mod:`backend.main` sans changement de
+comportement : mêmes chemins (``/api/health``, ``/api/health/detailed``),
+même ``response_model`` (:class:`backend.schemas.HealthResponse`), même
+dépendance admin. Seule différence : la version est lue via
+:func:`backend.version.get_version` au lieu de ``app.version`` (valeur
+identique, figée au démarrage depuis le fichier ``VERSION``).
+
+Note : ``uptime_seconds`` reprend l'expression d'origine
+(``'_SERVER_START_TIME' in globals()``), qui vaut toujours 0 — le global
+n'est défini nulle part dans ``backend.main`` (voir ``backend.admin`` qui
+possède son propre compteur). Ce comportement est préservé tel quel ; le
+corriger fera l'objet d'une tranche ultérieure avec test dédié.
+"""
+
+from fastapi import APIRouter, Depends
+
+from backend.auth.middleware import require_admin
+from backend.indexer import index
+from backend.schemas import HealthResponse
+from backend.version import get_git_commit, get_git_describe, get_version
+
+router = APIRouter(tags=["System"])
+
+
+@router.get("/api/health", response_model=HealthResponse)
+async def api_health():
+    """Health check endpoint for Docker and monitoring.
+
+    Returns:
+        Application status, version, vault count and total file count.
+    """
+    total_files = sum(len(v["files"]) for v in index.values())
+    total_tokens = sum(len(v.get("files", [])) * 1000 for v in index.values())  # rough approx
+    import time
+
+    from backend.indexer import _last_full_index_ts
+    # `_SERVER_START_TIME` n'existe dans aucun module (comportement d'origine
+    # préservé : uptime toujours 0 — voir docstring du module).
+    uptime = int(time.time() - _SERVER_START_TIME) if '_SERVER_START_TIME' in globals() else 0  # noqa: F821
+    return {
+        "status": "ok",
+        "version": get_version(),
+        "vaults": len(index),
+        "total_files": total_files,
+        "total_tokens": total_tokens,
+        "last_full_index_ts": _last_full_index_ts,
+        "uptime_seconds": uptime,
+        "git_describe": get_git_describe(),
+        "git_commit": get_git_commit(),
+    }
+
+
+@router.get("/api/health/detailed", response_model=HealthResponse)
+async def api_health_detailed(current_user=Depends(require_admin)):
+    """Detailed health check — admin only.
+
+    Returns enriched metrics including memory, disk, SSE connections, and backup stats.
+    """
+
+    import psutil
+
+    from backend.admin import _count_active_sessions, _get_disk_stats
+    from backend.indexer import _last_full_index_ts, index
+
+    total_files = sum(len(v["files"]) for v in index.values())
+    total_tokens = sum(len(v.get("files", [])) * 1000 for v in index.values())
+    import time
+    uptime = int(time.time() - _SERVER_START_TIME) if '_SERVER_START_TIME' in globals() else 0  # noqa: F821 — voir ci-dessus
+
+    # Memory
+    vm = psutil.virtual_memory()
+    mem_used_mb = round(vm.used / (1024 ** 2), 1)
+    mem_total_mb = round(vm.total / (1024 ** 2), 1)
+    mem_pct = round(vm.percent, 1)
+
+    # CPU
+    cpu_pct = psutil.cpu_percent(interval=None)
+
+    # Disk
+    disk_used_gb, disk_total_gb = _get_disk_stats()
+    disk_free_gb = round(disk_total_gb - disk_used_gb, 2)
+    disk_pct = round((disk_used_gb / disk_total_gb * 100) if disk_total_gb > 0 else 0, 1)
+
+    # SSE connections (approximation)
+    active_sessions = _count_active_sessions()
+
+    # Backups
+    from backend.admin import _scan_backups
+    backup_rows = _scan_backups()
+    total_backups = len(backup_rows)
+    total_backup_size_mb = round(sum(r["size"] for r in backup_rows) / (1024 ** 2), 2)
+    oldest_backup_age_days = 0.0
+    if backup_rows:
+        now_ts = int(time.time())
+        oldest_ts = min(r["timestamp"] for r in backup_rows)
+        oldest_backup_age_days = round((now_ts - oldest_ts) / 86400, 2)
+
+    # Index details
+    index_detail = {}
+    for name, data in index.items():
+        index_detail[name] = {
+            "file_count": len(data["files"]),
+            "tag_count": len(data.get("tags", [])),
+            "token_count_approx": len(data.get("files", [])) * 1000,
+        }
+
+    return {
+        "status": "ok",
+        "version": get_version(),
+        "vaults": len(index),
+        "total_files": total_files,
+        "total_tokens": total_tokens,
+        "last_full_index_ts": _last_full_index_ts,
+        "uptime_seconds": uptime,
+        "git_describe": get_git_describe(),
+        "git_commit": get_git_commit(),
+        # Enriched fields
+        "memory": {
+            "used_mb": mem_used_mb,
+            "total_mb": mem_total_mb,
+            "percent": mem_pct,
+        },
+        "cpu": {
+            "percent": cpu_pct,
+        },
+        "disk": {
+            "used_gb": disk_used_gb,
+            "total_gb": disk_total_gb,
+            "free_gb": disk_free_gb,
+            "percent": disk_pct,
+        },
+        "connections": {
+            "active_sse": active_sessions,
+        },
+        "backups": {
+            "total_count": total_backups,
+            "total_size_mb": total_backup_size_mb,
+            "oldest_age_days": oldest_backup_age_days,
+        },
+        "index": index_detail,
+    }
diff --git a/backend/schemas.py b/backend/schemas.py
index 07341ed..0961381 100644
--- a/backend/schemas.py
+++ b/backend/schemas.py
@@ -408,6 +408,31 @@ class DashboardResponse(BaseModel):
     total_images: int = 0
 
 
+# ---------------------------------------------------------------------------
+# System / health (#85 — extrait de backend.main, comportement inchangé)
+# ---------------------------------------------------------------------------
+
+
+class HealthResponse(BaseModel):
+    """Application health status.
+
+    Déplacé depuis :mod:`backend.main` sans modification : pas de
+    ``extra="allow"`` ici, pour préserver la validation actuelle des
+    réponses (les champs enrichis de ``/api/health/detailed`` restent
+    filtrés comme avant).
+    """
+
+    status: str = Field(description="Health status ('ok' or 'error')")
+    version: str = Field(description="Application version (x.y.z — latest release tag)")
+    vaults: int = Field(description="Number of configured vaults")
+    total_files: int = Field(description="Total indexed files across all vaults")
+    total_tokens: int = Field(description="Total indexed tokens (approx.) across all vaults", default=0)
+    last_full_index_ts: str = Field(description="ISO timestamp of last full index rebuild", default="")
+    uptime_seconds: int = Field(description="Server uptime in seconds", default=0)
+    git_describe: str = Field(default="", description="Full git describe string (commits beyond tag), empty if no git")
+    git_commit: str = Field(default="", description="Short HEAD commit hash, empty if no git")
+
+
 # ---------------------------------------------------------------------------
 # Webhooks, sharing & conflicts
 # ---------------------------------------------------------------------------
diff --git a/desktop/Cargo.lock b/desktop/Cargo.lock
index 4cd164c..f373c73 100644
--- a/desktop/Cargo.lock
+++ b/desktop/Cargo.lock
@@ -2626,7 +2626,7 @@ dependencies = [
 
 [[package]]
 name = "obsigate-desktop"
-version = "2.27.1"
+version = "2.27.2"
 dependencies = [
  "chrono",
  "env_logger",
diff --git a/desktop/Cargo.toml b/desktop/Cargo.toml
index eb8c9ad..244891c 100644
--- a/desktop/Cargo.toml
+++ b/desktop/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "obsigate-desktop"
-version = "2.27.1"
+version = "2.27.2"
 description = "ObsiGate Desktop — Porte d'entrée native pour vos vaults Obsidian"
 authors = ["Bruno Charest"]
 edition = "2021"
diff --git a/desktop/tauri.conf.json b/desktop/tauri.conf.json
index d20e750..d61ffa1 100644
--- a/desktop/tauri.conf.json
+++ b/desktop/tauri.conf.json
@@ -1,7 +1,7 @@
 {
   "$schema": "https://raw.githubusercontent.com/nicedoc/obsigate/main/desktop/tauri.conf.schema.json",
   "productName": "ObsiGate",
-  "version": "2.27.1",
+  "version": "2.27.2",
   "identifier": "com.obsigate.desktop",
   "build": {
     "frontendDist": "../frontend",
diff --git a/docs/ROADMAP.md b/docs/ROADMAP.md
index 8e0a40a..1221319 100644
--- a/docs/ROADMAP.md
+++ b/docs/ROADMAP.md
@@ -1,6 +1,6 @@
 # ObsiGate — Roadmap
 
-> **Version :** 2.27.1 | **Dernière mise à jour :** 2026-09-26
+> **Version :** 2.27.2 | **Dernière mise à jour :** 2026-09-26
 > **Ce fichier ne contient que le travail à venir** (🔵 En cours + ⚪ Backlog) et un index compact
 > vers les fonctionnalités livrées.
 > - **Méthode de livraison à appliquer pour toute tâche : [DELIVERY_WORKFLOW.md](./DELIVERY_WORKFLOW.md)**
@@ -67,10 +67,11 @@
 
 - **Effort :** 8-12 jours | **Impact :** 🟡 | **Zone :** backend
 - **Décision 2026-09-26 : prioritaire (axe Dette & sécurité).**
+- **Statut :** 🔵 en cours depuis 2026-09-26 — découpe par tranches à impact minimal (comportement inchangé, un domaine par commit). **T1 livrée (v2.27.2) :** `health` (`/api/health`, `/api/health/detailed` → `backend/routers/health.py`, `HealthResponse` → `schemas.py`).
 - **Description :** extraire le monolithe `backend/main.py` (~4 827 lignes au 2026-09-26, ~17 % du backend) en routers FastAPI par domaine et rendre persistant l'état qui ne l'est pas (index de recherche, JTI révoqués, compteurs de rate-limit) pour préparer le multi-nœuds. L'état mémoire actuel (index, inverted index, vecteurs sémantiques, `SSEManager`, collab) rend le multi-workers unsafe.
 - **Sous-tâches :**
-  - [ ] Routers par domaine : files, search, share, webhooks, plugins, collab, admin, ai — `main.py` conservé comme assemblage (< 500 lignes) ; dédupliquer les modèles Pydantic vers `schemas.py`
-  - [ ] Créer `tools/registry.py` (inexistant) : contrat central des outils IA (permissions, quotas, redaction)
+  - [ ] Routers par domaine : files, search, share, webhooks, plugins, collab, admin, ai — `main.py` conservé comme assemblage (< 500 lignes) ; dédupliquer les modèles Pydantic vers `schemas.py`. **Avancement :** `health` ✅ (T1, `backend/routers/health.py`) ; `tools/registry.py` existe déjà (permissions/quotas/redaction — à compléter, pas à créer)
+  - [ ] Compléter `tools/registry.py` (existant : permissions/quotas/redaction) comme contrat central des outils IA si des manques sont constatés
   - [ ] Persister index, JTI révoqués et compteurs de rate-limit (SQLite par défaut, Redis en option multi-nœuds ; le rate-limit actuel est in-memory mono-process)
   - [ ] Verrous asyncio autour de l'index global et des stores JSON ; auditer les `except Exception` larges (> 100 occurrences) : best-effort (backup/audit) vs masquage d'erreur (erreurs typées 4xx/5xx + test)
   - [ ] Extraire le service de partage public (expiration, révocation, quotas)
diff --git a/package.json b/package.json
index 6460a24..873eed1 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "obsigate",
-  "version": "2.27.1",
+  "version": "2.27.2",
   "description": "**Porte d'entrée web ultra-léger pour vos vaults Obsidian** — Accédez, naviguez et recherchez dans toutes vos notes Obsidian depuis n'importe quel appareil via une interface web moderne et responsive.",
   "main": "patch.js",
   "directories": {