feat(ai): assistant AI multi-contexte + ergonomie sidebar et clavier

Contexte:
- Repertoire (mode historique BooksLM, via menu contextuel dossier)
- Documents (bouton flottant quand des documents sont ouverts)
- General (bouton flottant sans document: aide app + creation de fichiers)
- Le contexte est affiche dans le header; suggestions adaptees au mode
- Blocs obsigate-action rendus en carte avec bouton Appliquer (pas d'execution auto)

Backend:
- /api/ai/bookslm/context et /chat acceptent mode + context_files
- collect_files_context(), empty_context(), build_general_system_prompt()
- mode documents degrade vers general si aucun fichier lisible

Corrige:
- bouton flottant passait le chemin d'un fichier comme repertoire -> erreur
  'Aucun fichier markdown trouve dans ce dossier'
- panneau precedent masque (localStorage) ne se rouvrait plus
- selecteur fournisseur/modele deplace sur une ligne dediee (header actions visibles)
- Entree envoie, Ctrl+Entree insere un saut de ligne

Tests: test_bookslm.py (+13) et tests/frontend/ai.test.mjs (+8)

backend/bookslm_routes.py

@@ -9,25 +9,43 @@ from fastapi.responses import StreamingResponse
 from pydantic import BaseModel, Field
 
 from backend.auth.middleware import check_vault_access, require_auth
-from backend.bookslm import build_system_prompt, collect_directory_context
-from backend.indexer import get_vault_data
+from backend.bookslm import (
+    build_general_system_prompt,
+    build_system_prompt,
+    collect_directory_context,
+    collect_files_context,
+    empty_context,
+)
+from backend.indexer import get_vault_data, index
 from backend.schemas import BooksLMContextResponse
 
 logger = logging.getLogger("obsigate.bookslm_routes")
 router = APIRouter(prefix="/api/ai/bookslm", tags=["BooksLM"])
 
+VALID_MODES = {"directory", "documents", "general"}
+
 
 # ── Request models ──
 
 
 class BooksLMContextRequest(BaseModel):
-    vault: str = Field(description="Vault name")
+    vault: str | None = Field(default=None, description="Vault name (required for directory/documents modes)")
     directory: str = Field(default="", description="Relative directory path within the vault")
+    mode: str = Field(default="directory", description="Context mode: 'directory', 'documents' or 'general'")
+    context_files: list[str] = Field(
+        default_factory=list,
+        description="Relative file paths to use as context (documents mode)",
+    )
 
 
 class BooksLMChatRequest(BaseModel):
-    vault: str = Field(description="Vault name")
+    vault: str | None = Field(default=None, description="Vault name (required for directory/documents modes)")
     directory: str = Field(default="", description="Relative directory path within the vault")
+    mode: str = Field(default="directory", description="Context mode: 'directory', 'documents' or 'general'")
+    context_files: list[str] = Field(
+        default_factory=list,
+        description="Relative file paths to use as context (documents mode)",
+    )
     message: str = Field(description="User message")
     conversation_history: list[dict[str, str]] = Field(
         default_factory=list,
@@ -44,6 +62,34 @@ class BooksLMChatRequest(BaseModel):
     )
 
 
+def _normalize_mode(mode: str | None) -> str:
+    mode = (mode or "directory").lower()
+    return mode if mode in VALID_MODES else "directory"
+
+
+def _resolve_vault_path(vault: str | None, current_user):
+    """Validate vault access and return (vault_name, vault_path)."""
+    if not vault:
+        raise HTTPException(status_code=400, detail="Champ 'vault' requis pour ce contexte")
+    if not check_vault_access(vault, current_user):
+        raise HTTPException(status_code=403, detail=f"Accès refusé à la vault '{vault}'")
+    vault_data = get_vault_data(vault)
+    if not vault_data:
+        raise HTTPException(status_code=404, detail=f"Vault '{vault}' not found")
+    return vault, Path(vault_data["path"])
+
+
+def _build_context(mode: str, vault_path: Path | None, directory: str, context_files: list[str]):
+    """Collect the context payload for the requested mode."""
+    if mode == "general":
+        return empty_context("general")
+    if mode == "documents":
+        ctx = collect_files_context(vault_path, context_files, scope="documents")  # type: ignore[arg-type]
+        # No open document could be read → degrade gracefully to General.
+        return ctx if ctx["file_count"] else empty_context("general")
+    return collect_directory_context(vault_path, directory)  # type: ignore[arg-type]
+
+
 # ── Endpoints ──
 
 
@@ -52,20 +98,21 @@ async def api_bookslm_context(
     req: BooksLMContextRequest,
     current_user=Depends(require_auth),
 ):
-    """Collect directory context for BooksLM.
+    """Collect context for the AI assistant.
 
-    Returns file list, content, and metadata for the specified directory.
+    Three modes are supported:
+
+    * ``directory`` — every supported file under a vault directory;
+    * ``documents`` — only the explicitly listed open documents;
+    * ``general`` — no document context (assistant for the app itself).
     """
-    if not check_vault_access(req.vault, current_user):
-        raise HTTPException(status_code=403, detail=f"Accès refusé à la vault '{req.vault}'")
+    mode = _normalize_mode(req.mode)
+    if mode == "general":
+        return empty_context("general")
 
-    vault_data = get_vault_data(req.vault)
-    if not vault_data:
-        raise HTTPException(status_code=404, detail=f"Vault '{req.vault}' not found")
-
-    vault_path = Path(vault_data["path"])
-    context = collect_directory_context(vault_path, req.directory)
-    return context
+    _resolve_vault_path(req.vault, current_user)
+    vault_path = Path(get_vault_data(req.vault)["path"])  # type: ignore[index]
+    return _build_context(mode, vault_path, req.directory, req.context_files)
 
 
 @router.post(
@@ -77,28 +124,32 @@ async def api_bookslm_chat(
     req: BooksLMChatRequest,
     current_user=Depends(require_auth),
 ):
-    """Chat with AI about directory contents (BooksLM).
+    """Chat with the AI assistant.
 
-    Builds context from the directory, then sends the user message
-    with a system prompt containing all file contents to the AI provider.
-    Returns an SSE stream with the response.
+    Builds a system prompt from the selected context (directory, open
+    documents or general app knowledge), then streams the provider's answer
+    as Server-Sent Events.
     """
-    if not check_vault_access(req.vault, current_user):
-        raise HTTPException(status_code=403, detail=f"Accès refusé à la vault '{req.vault}'")
+    mode = _normalize_mode(req.mode)
 
-    vault_data = get_vault_data(req.vault)
-    if not vault_data:
-        raise HTTPException(status_code=404, detail=f"Vault '{req.vault}' not found")
-
-    vault_path = Path(vault_data["path"])
+    vault_path: Path | None = None
+    if mode != "general":
+        _resolve_vault_path(req.vault, current_user)
+        vault_path = Path(get_vault_data(req.vault)["path"])  # type: ignore[index]
 
     # Collect context
-    context = collect_directory_context(vault_path, req.directory)
-    if context["file_count"] == 0:
-        raise HTTPException(status_code=404, detail="Aucun fichier markdown trouvé dans ce dossier")
+    context = _build_context(mode, vault_path, req.directory, req.context_files)
+    effective_mode = context.get("scope", mode)
 
     # Build system prompt
-    system_prompt = build_system_prompt(context)
+    if effective_mode == "general":
+        system_prompt = build_general_system_prompt(list(index.keys()))
+    elif effective_mode == "documents":
+        system_prompt = build_system_prompt(context, scope="documents")
+    else:
+        if context["file_count"] == 0:
+            raise HTTPException(status_code=404, detail="Aucun fichier markdown trouvé dans ce dossier")
+        system_prompt = build_system_prompt(context, scope="directory")
 
     # Call AI provider
     from backend.ai import DEFAULT_PROVIDER, PROVIDERS, _call_deepseek_openrouter, _call_gemini