feat(ai): menu @ instantane, selecteurs agrandis et BooksLM racine (#82)

Nouvel endpoint GET /api/vault/{vault}/paths + prechargement et filtrage client du menu @ (affichage instantane des fichiers/repertoires). Selecteurs Fournisseur/Modele agrandis (0,8rem / 34px) pour s'aligner sur le reste du site. Ajout de BooksLM au menu contextuel de la racine des vaults.

backend/main.py

@@ -136,7 +136,7 @@ from backend.services.mutations import (
     restore_backup as service_restore_backup,
 )
 from backend.services.recent import humanize_mtime, list_recent
-from backend.services.search import advanced_search_vaults, search_paths, search_vaults
+from backend.services.search import advanced_search_vaults, list_paths, search_paths, search_vaults
 from backend.services.search import list_tags as service_list_tags
 from backend.services.vaults import (
     browse_directory,
@@ -276,6 +276,21 @@ class TreeSearchResponse(BaseModel):
     results: list[TreeSearchResult] = Field(description="Matching files and directories")
 
 
+class VaultPathEntry(BaseModel):
+    """A single indexed path (file or directory) in a vault."""
+    vault: str = Field(description="Vault name")
+    path: str = Field(description="Full relative path")
+    name: str = Field(description="File or directory name")
+    type: str = Field(description="'file' or 'directory'")
+
+
+class VaultPathsResponse(BaseModel):
+    """Flat list of every indexed path in a vault (capped)."""
+    vault: str = Field(description="Vault name")
+    count: int = Field(description="Number of returned entries")
+    results: list[VaultPathEntry] = Field(description="Indexed files and directories")
+
+
 class AdvancedSearchResultItem(BaseModel):
     """A single advanced search result with highlighted snippet."""
     vault: str = Field(description="Vault name")
@@ -2580,6 +2595,29 @@ async def api_tree_search(
     return search_paths(q, vault)
 
 
+@app.get("/api/vault/{vault_name}/paths", response_model=VaultPathsResponse)
+async def api_vault_paths(
+    vault_name: str,
+    limit: int = Query(5000, ge=1, le=20000, description="Maximum number of indexed paths to return"),
+    current_user=Depends(require_auth),
+):
+    """Return a flat list of every indexed file and directory in a vault.
+
+    Used by the AI assistant ``@`` mention menu to filter paths instantly on
+    the client (one request instead of one per keystroke).
+
+    Args:
+        vault_name: Name of the vault.
+        limit: Maximum number of entries returned.
+
+    Returns:
+        ``VaultPathsResponse`` with the vault's indexed paths.
+    """
+    if not check_vault_access(vault_name, current_user):
+        raise HTTPException(status_code=403, detail=f"Accès refusé à la vault '{vault_name}'")
+    return list_paths(vault_name, limit=limit)
+
+
 @app.get("/api/search/advanced", response_model=AdvancedSearchResponse)
 async def api_advanced_search(
     q: str = Query("", description="Advanced search query (supports tag:, vault:, title:, path:, ext: operators)"),

backend/services/search.py

@@ -113,3 +113,32 @@ def search_paths(q: str, vault: str = "all") -> dict[str, Any]:
                 })
 
     return {"query": q, "vault_filter": vault, "results": results}
+
+
+def list_paths(vault: str, limit: int = 5000) -> dict[str, Any]:
+    """Return a flat, capped list of every indexed path in a vault.
+
+    Backs the AI assistant ``@`` mention menu: fetching the whole path index
+    once lets the client filter files/directories instantly instead of issuing
+    a request per keystroke.
+
+    Args:
+        vault: Vault name.
+        limit: Maximum number of entries returned.
+
+    Returns:
+        ``{"vault", "count", "results": [{vault, path, name, type}]}``.
+    """
+    from backend.indexer import path_index
+
+    entries = path_index.get(vault, [])
+    results = [
+        {
+            "vault": vault,
+            "path": entry["path"],
+            "name": entry["name"],
+            "type": entry["type"],
+        }
+        for entry in entries[: max(0, limit)]
+    ]
+    return {"vault": vault, "count": len(results), "results": results}