fix: harden cron tool contract and repeat guard

tests/agent/test_runner.py

@@ -798,6 +798,48 @@ async def test_runner_blocks_repeated_external_fetches():
     assert "repeated external lookup blocked" in blocked_tool_message["content"]
 
 
+@pytest.mark.asyncio
+async def test_runner_blocks_repeated_identical_tool_calls():
+    from nanobot.agent.runner import AgentRunSpec, AgentRunner
+
+    provider = MagicMock()
+    captured_final_call: list[dict] = []
+    call_count = {"n": 0}
+
+    async def chat_with_retry(*, messages, **kwargs):
+        call_count["n"] += 1
+        if call_count["n"] <= 3:
+            return LLMResponse(
+                content="working",
+                tool_calls=[ToolCallRequest(id=f"call_{call_count['n']}", name="read_file", arguments={"path": "memory/history.jsonl", "limit": 50, "offset": 1})],
+                usage={},
+            )
+        captured_final_call[:] = messages
+        return LLMResponse(content="done", tool_calls=[], usage={})
+
+    provider.chat_with_retry = chat_with_retry
+    tools = MagicMock()
+    tools.get_definitions.return_value = []
+    tools.execute = AsyncMock(return_value="file content")
+
+    runner = AgentRunner(provider)
+    result = await runner.run(AgentRunSpec(
+        initial_messages=[{"role": "user", "content": "what happened recently?"}],
+        tools=tools,
+        model="test-model",
+        max_iterations=4,
+        max_tool_result_chars=_MAX_TOOL_RESULT_CHARS,
+    ))
+
+    assert result.final_content == "done"
+    assert tools.execute.await_count == 2
+    blocked_tool_message = [
+        msg for msg in captured_final_call
+        if msg.get("role") == "tool" and msg.get("tool_call_id") == "call_3"
+    ][0]
+    assert "repeated identical call to 'read_file' blocked" in blocked_tool_message["content"]
+
+
 @pytest.mark.asyncio
 async def test_loop_max_iterations_message_stays_stable(tmp_path):
     loop = _make_loop(tmp_path)

tests/cron/test_cron_tool_list.py

@@ -7,7 +7,6 @@ import pytest
 from nanobot.agent.tools.cron import CronTool
 from nanobot.cron.service import CronService
 from nanobot.cron.types import CronJob, CronJobState, CronPayload, CronSchedule
-from tests.test_openai_api import pytest_plugins
 
 
 def _make_tool(tmp_path) -> CronTool:
@@ -346,6 +345,47 @@ def test_add_job_can_disable_delivery(tmp_path) -> None:
     assert job.payload.deliver is False
 
 
+def test_cron_schema_advertises_action_specific_requirements(tmp_path) -> None:
+    tool = _make_tool(tmp_path)
+
+    assert tool.parameters["required"] == ["action"]
+    assert tool.parameters["oneOf"] == [
+        {
+            "properties": {
+                "action": {"enum": ["add"]},
+                "message": {"type": "string", "minLength": 1},
+            },
+            "required": ["action", "message"],
+        },
+        {
+            "properties": {"action": {"enum": ["list"]}},
+            "required": ["action"],
+        },
+        {
+            "properties": {"action": {"enum": ["remove"]}},
+            "required": ["action", "job_id"],
+        },
+    ]
+
+
+def test_validate_params_requires_message_only_for_add(tmp_path) -> None:
+    tool = _make_tool(tmp_path)
+
+    assert "message is required when action='add'" in tool.validate_params({"action": "add"})
+    assert tool.validate_params({"action": "list"}) == []
+    assert "job_id is required when action='remove'" in tool.validate_params({"action": "remove"})
+
+
+def test_add_job_empty_message_returns_actionable_error(tmp_path) -> None:
+    tool = _make_tool(tmp_path)
+    tool.set_context("telegram", "chat-1")
+
+    result = tool._add_job(None, "", 60, None, None, None)
+
+    assert "action='add' requires a non-empty 'message'" in result
+    assert "Retry including message=" in result
+
+
 def test_list_excludes_disabled_jobs(tmp_path) -> None:
     tool = _make_tool(tmp_path)
     job = tool._cron.add_job(

tests/utils/test_runtime.py

@@ -0,0 +1,20 @@
+from nanobot.utils.runtime import repeated_tool_call_error, tool_call_signature
+
+
+def test_tool_call_signature_sorts_arguments_stably() -> None:
+    first = tool_call_signature("read_file", {"offset": 1, "path": "memory/history.jsonl"})
+    second = tool_call_signature("read_file", {"path": "memory/history.jsonl", "offset": 1})
+
+    assert first == second
+
+
+def test_repeated_tool_call_error_blocks_after_two_attempts() -> None:
+    seen: dict[str, int] = {}
+
+    assert repeated_tool_call_error("read_file", {"path": "a.txt"}, seen) is None
+    assert repeated_tool_call_error("read_file", {"path": "a.txt"}, seen) is None
+
+    error = repeated_tool_call_error("read_file", {"path": "a.txt"}, seen)
+
+    assert error is not None
+    assert "repeated identical call to 'read_file' blocked after 2 attempts" in error