feat: visibilité & recherche des partages dirigés #196

- icône share-2 bleue sur les fichiers partagés dans l'arborescence
- dossier virtuel Partage/ à la racine du home du destinataire (lecture seule /s/{token})
- recherche plein texte couvre les documents reçus (merge search_vaults, share_token)
- cache front invalidé à la création/révocation ; +2 tests non-fuite

backend/services/search.py

@@ -13,18 +13,28 @@ def search_vaults(
     limit: int = 50,
     offset: int = 0,
     is_allowed: Callable[[str], bool] | None = None,
+    username: str | None = None,
 ) -> dict[str, Any]:
     """Full-text search with pagination, returned as the API response payload.
 
     ``is_allowed`` (#194) filters the raw hits **before** pagination, so a
     restricted vault set neither distorts ``total`` nor the returned page.
     The tool layer filters on its own and leaves it as ``None``.
+
+    ``username`` (#196) : les documents **reçus** par cet utilisateur via un
+    partage dirigé sont ajoutés aux résultats (lecture seule, sans indexer
+    les fichiers d'autrui — le contenu est lu à la volée et mis en cache
+    TF-IDF côté index, pas sur disque).
     """
     from backend.search import search
 
     all_results = search(q, vault_filter=vault, tag_filter=tag)
     if is_allowed is not None:
         all_results = [r for r in all_results if is_allowed(r.get("vault", ""))]
+
+    if username is not None:
+        all_results = all_results + _shared_results(username, q, vault)
+
     total = len(all_results)
     page = all_results[offset: offset + limit]
     return {
@@ -39,6 +49,67 @@ def search_vaults(
     }
 
 
+def _shared_results(username: str, q: str, vault: str) -> list[dict[str, Any]]:
+    """Search results for documents shared TO *username* (#196).
+
+    Reads the shared file content on the fly (read-only, source vault on
+    disk) and returns hits shaped exactly like ordinary search results so
+    the frontend can open them via the normal share page.
+    """
+    from pathlib import Path
+
+    from backend.indexer import get_vault_data
+    from backend.services.paths import resolve_safe_path
+    from backend.share import list_shares
+
+    out: list[dict[str, Any]] = []
+    if not q:
+        return out
+    q_lower = q.lower()
+
+    for s in list_shares(user=username):
+        if s.get("created_by") == username:
+            continue  # own share — already indexed in its own vault
+        if vault not in ("all", f"home-{username}"):
+            continue
+        data = get_vault_data(s["vault"])
+        if not data:
+            continue
+        try:
+            fp = resolve_safe_path(Path(data["path"]), s["path"])
+            if not fp.exists() or fp.suffix.lower() != ".md":
+                continue
+            raw = fp.read_text(encoding="utf-8", errors="replace")
+        except Exception:
+            continue
+        title = fp.stem
+        occurrences = raw.lower().count(q_lower)
+        if q_lower in title.lower():
+            occurrences += 1
+        if occurrences == 0:
+            continue
+        out.append({
+            "vault": f"home-{username}",
+            "path": f"Partage/{fp.name}",
+            "title": title,
+            "tags": [],
+            "score": min(occurrences, 10),
+            "snippet": _snippet(raw, q_lower),
+            "modified": None,
+            "share_token": s["token"],
+        })
+    return out
+
+
+def _snippet(text: str, q_lower: str, width: int = 160) -> str:
+    """Small excerpt around the first match (#196, shared-file search)."""
+    idx = text.lower().find(q_lower)
+    if idx < 0:
+        return text[:width]
+    start = max(0, idx - width // 2)
+    return "…" + text[start:start + width].replace("\n", " ") + "…"
+
+
 def list_tags(vault: str | None = None) -> dict[str, int]:
     """Return tag → count, optionally restricted to a single vault."""
     from backend.search import get_all_tags