fix(agent): preserve none vs unknown tool effects (#61783)

* fix(agent): persist truthful tool effect dispositions

* fix(agent): preserve successful siblings during orphan recovery

* fix(agent): narrow effect dispositions to none and unknown

agent/tool_result_classification.py

@@ -9,6 +9,20 @@ from typing import Any
 FILE_MUTATING_TOOL_NAMES = frozenset({"write_file", "patch"})
 
 
+# Tools whose interrupted/dangling execution is safe to discard because they
+# cannot mutate either external state or Hermes session state. Unknown/plugin/
+# MCP tools stay effect-capable by default.
+NO_EFFECT_TOOL_NAMES = frozenset({
+    "read_file", "search_files", "session_search", "skill_view", "skills_list",
+    "web_extract", "web_search", "vision_analyze", "browser_snapshot",
+    "browser_get_images", "browser_console", "read_terminal",
+})
+
+
+def tool_may_have_side_effect(tool_name: str) -> bool:
+    return tool_name not in NO_EFFECT_TOOL_NAMES
+
+
 def file_mutation_result_landed(tool_name: str, result: Any) -> bool:
     """Return True when a file mutation result proves the write landed."""
     if tool_name not in FILE_MUTATING_TOOL_NAMES or not isinstance(result, str):