feat(ai): durcissement phase F (#79) - rate limit, redaction, OpenAPI/MCP, E2E

backend/tools/service.py

@@ -11,6 +11,7 @@ confirmation mechanism (two-step propose/apply).
 from __future__ import annotations
 
 import logging
+import os
 from typing import Any
 
 from backend.indexer import get_backlinks as _get_backlinks
@@ -90,8 +91,9 @@ from backend.tools.schemas import (
 
 logger = logging.getLogger("obsigate.tools.service")
 
-# Maximum file size returned by ``read_file`` (bytes).
-TOOL_MAX_READ_BYTES = 200_000
+# Maximum file size returned by ``read_file`` (bytes). Quota configurable via
+# ``BOOKSLM_MAX_TOOL_READ_BYTES``.
+TOOL_MAX_READ_BYTES = int(os.environ.get("BOOKSLM_MAX_TOOL_READ_BYTES", "200000"))
 
 
 # ── C1. Vaults / navigation ────────────────────────────────────────────────