Improve tool call validation strictness (#4190)

* Improve tool call validation strictness

Reject near-miss tool names without executing suggested tools. Require object-shaped tool parameters while preserving only lossless JSON wire-shape normalization.

* Tighten tool call argument validation

* Simplify tool argument validation tests

* Improve tool name suggestions

* Simplify tool suggestion helpers

* Limit tool suggestions to canonical matches

* Allow repair only for tool history replay

* Clarify non-object tool argument errors

* Inline replay tool argument normalization

* Track only successful tool executions

* Reject JSON null tool arguments

nanobot/utils/progress_events.py

@@ -49,13 +49,18 @@ async def invoke_file_edit_progress(
     await on_progress("", file_edit_events=file_edit_events)
 
 
+def _tool_event_arguments(tool_call: Any) -> dict[str, Any]:
+    arguments = getattr(tool_call, "arguments", {}) or {}
+    return arguments if isinstance(arguments, dict) else {}
+
+
 def build_tool_event_start_payload(tool_call: Any) -> dict[str, Any]:
     return {
         "version": 1,
         "phase": "start",
         "call_id": str(getattr(tool_call, "id", "") or ""),
         "name": getattr(tool_call, "name", ""),
-        "arguments": getattr(tool_call, "arguments", {}) or {},
+        "arguments": _tool_event_arguments(tool_call),
         "result": None,
         "error": None,
         "files": [],
@@ -86,7 +91,7 @@ def build_tool_event_finish_payloads(context: AgentHookContext) -> list[dict[str
             "phase": phase,
             "call_id": str(getattr(tool_call, "id", "") or ""),
             "name": getattr(tool_call, "name", ""),
-            "arguments": getattr(tool_call, "arguments", {}) or {},
+            "arguments": _tool_event_arguments(tool_call),
             "result": result if phase == "end" else None,
             "error": None,
             "files": files,

nanobot/utils/runtime.py

@@ -75,8 +75,10 @@ def build_goal_continue_message(custom: str | None = None) -> dict[str, str]:
     return {"role": "user", "content": custom or SUSTAINED_GOAL_CONTINUE_PROMPT}
 
 
-def external_lookup_signature(tool_name: str, arguments: dict[str, Any]) -> str | None:
+def external_lookup_signature(tool_name: str, arguments: Any) -> str | None:
     """Stable signature for repeated external lookups we want to throttle."""
+    if not isinstance(arguments, dict):
+        return None
     if tool_name == "web_fetch":
         url = str(arguments.get("url") or "").strip()
         if url:
@@ -90,7 +92,7 @@ def external_lookup_signature(tool_name: str, arguments: dict[str, Any]) -> str
 
 def repeated_external_lookup_error(
     tool_name: str,
-    arguments: dict[str, Any],
+    arguments: Any,
     seen_counts: dict[str, int],
 ) -> str | None:
     """Block repeated external lookups after a small retry budget."""
@@ -119,9 +121,11 @@ _OUTSIDE_PATH_PATTERN = re.compile(r"(?:^|[\s|>'\"])((?:/[^\s\"'>;|<]+)|(?:~[^\s
 
 def workspace_violation_signature(
     tool_name: str,
-    arguments: dict[str, Any],
+    arguments: Any,
 ) -> str | None:
     """Return a stable cross-tool signature for the outside-workspace target."""
+    if not isinstance(arguments, dict):
+        return None
     for key in ("path", "file_path", "target", "source", "destination"):
         val = arguments.get(key)
         if isinstance(val, str) and val.strip():
@@ -151,7 +155,7 @@ def _normalize_violation_target(raw: str) -> str:
 
 def repeated_workspace_violation_error(
     tool_name: str,
-    arguments: dict[str, Any],
+    arguments: Any,
     seen_counts: dict[str, int],
 ) -> str | None:
     """Return an escalated error after repeated bypass attempts."""