fix: partage dirigé — dossier Partage virtuel + ouverture en onglet #196

- _resolve_shared_file: home-<user>/Partage/<f> -> fichier source (/api/file, raw, download)
- clic dossier Partage: dépliage sans navigation (fix Directory not found)
- fichiers reçus ouverts en onglet applicatif (arbre, recherche, dashboard)
- POST /api/share: path vide/null rejeté (400) — un share path:null cassait /api/shares
- +2 tests (13 total)

backend/routers/files_read.py

@@ -45,9 +45,32 @@ from backend.services.files import read_raw_file
 from backend.services.mutations import file_revision
 from backend.services.paths import resolve_safe_path
 from backend.services.vaults import browse_directory, get_vault_root
+from backend.share import list_shares
 
 logger = logging.getLogger("obsigate")
 
+
+def _resolve_shared_file(vault_name: str, path: str, username: str | None):
+    """#196 — resolve ``home-<user>/Partage/<file>`` to the real source file.
+
+    Returns ``(real_vault, real_path)`` when *path* is a received share
+    mounted in the user's personal folder, else ``None``. Read-only: only a
+    recipient (or the share creator, whose own file is already accessible)
+    gets a mapping — a share directed to someone else never resolves here.
+    """
+    if not username or not vault_name.startswith("home-") or not path.startswith("Partage/"):
+        return None
+    owner = vault_name[len("home-"):]
+    if owner != username:
+        return None
+    name = path.split("/", 1)[1]
+    for s in list_shares(user=username):
+        if s.get("created_by") == username:
+            continue
+        if (s.get("path") or "").split("/")[-1] == name:
+            return s["vault"], s["path"]
+    return None
+
 # Map file extensions to highlight.js language hints
 EXT_TO_LANG = {
     ".py": "python", ".js": "javascript", ".ts": "typescript",
@@ -104,6 +127,9 @@ async def api_file_raw(vault_name: str, path: str = Query(..., description="Rela
     Returns:
         ``FileRawResponse`` with vault, path, and raw text content.
     """
+    shared = _resolve_shared_file(vault_name, path, current_user.get("username"))
+    if shared:
+        vault_name, path = shared
     if not check_vault_access(vault_name, current_user):
         raise HTTPException(status_code=403, detail=f"Accès refusé à la vault '{vault_name}'")
     return read_raw_file(vault_name, path)
@@ -120,6 +146,9 @@ async def api_file_download(vault_name: str, path: str = Query(..., description=
     Returns:
         ``FileResponse`` with ``application/octet-stream`` content-type.
     """
+    shared = _resolve_shared_file(vault_name, path, current_user.get("username"))
+    if shared:
+        vault_name, path = shared
     if not check_vault_access(vault_name, current_user):
         raise HTTPException(status_code=403, detail=f"Accès refusé à la vault '{vault_name}'")
     vault_data = get_vault_data(vault_name)
@@ -305,8 +334,17 @@ async def api_file(vault_name: str, path: str = Query(..., description="Relative
     Returns:
         ``FileContentResponse`` with HTML, metadata, and tags.
     """
+    # #196 — fichier reçu par partage dirigé : home-<user>/Partage/<fichier>
+    # est résolu vers le fichier source (lecture seule, viewer standard).
+    # Résolu AVANT l'ACL vault : le dossier est virtuel, l'autorisation réelle
+    # est l'appartenance au partage (vérifiée dans le resolver).
+    shared = _resolve_shared_file(vault_name, path, current_user.get("username"))
+    if shared:
+        vault_name, path = shared
+
     if not check_vault_access(vault_name, current_user):
         raise HTTPException(status_code=403, detail=f"Accès refusé à la vault '{vault_name}'")
+
     vault_data = get_vault_data(vault_name)
     if not vault_data:
         raise HTTPException(status_code=404, detail=f"Vault '{vault_name}' not found")

backend/routers/sharing.py

@@ -88,7 +88,9 @@ async def api_share_create(
     """
     if not check_vault_access(vault_name, current_user):
         raise HTTPException(403, f"Accès refusé à la vault '{vault_name}'")
-    path = body.get("path", "")
+    path = body.get("path") or ""
+    if not path:
+        raise HTTPException(400, "Chemin de fichier requis")
     expires = body.get("expires_in_hours")
     # #196 — directed share: validate recipients before creating anything.
     recipients = body.get("shared_with") or []