diff --git a/nanobot/providers/base.py b/nanobot/providers/base.py
index c51f5ddaf..852e9c973 100644
--- a/nanobot/providers/base.py
+++ b/nanobot/providers/base.py
@@ -72,6 +72,7 @@ class LLMProvider(ABC):
 
     _CHAT_RETRY_DELAYS = (1, 2, 4)
     _PERSISTENT_MAX_DELAY = 60
+    _PERSISTENT_IDENTICAL_ERROR_LIMIT = 10
     _RETRY_HEARTBEAT_CHUNK = 30
     _TRANSIENT_ERROR_MARKERS = (
         "429",
@@ -377,12 +378,20 @@ class LLMProvider(ABC):
         delays = list(self._CHAT_RETRY_DELAYS)
         persistent = retry_mode == "persistent"
         last_response: LLMResponse | None = None
+        last_error_key: str | None = None
+        identical_error_count = 0
         while True:
             attempt += 1
             response = await call(**kw)
             if response.finish_reason != "error":
                 return response
             last_response = response
+            error_key = ((response.content or "").strip().lower() or None)
+            if error_key and error_key == last_error_key:
+                identical_error_count += 1
+            else:
+                last_error_key = error_key
+                identical_error_count = 1 if error_key else 0
 
             if not self._is_transient_error(response.content):
                 stripped = self._strip_image_content(original_messages)
@@ -395,6 +404,14 @@ class LLMProvider(ABC):
                     return await call(**retry_kw)
                 return response
 
+            if persistent and identical_error_count >= self._PERSISTENT_IDENTICAL_ERROR_LIMIT:
+                logger.warning(
+                    "Stopping persistent retry after {} identical transient errors: {}",
+                    identical_error_count,
+                    (response.content or "")[:120].lower(),
+                )
+                return response
+
             if not persistent and attempt > len(delays):
                 break
 
diff --git a/nanobot/utils/helpers.py b/nanobot/utils/helpers.py
index cca2992ec..fa3e423b8 100644
--- a/nanobot/utils/helpers.py
+++ b/nanobot/utils/helpers.py
@@ -11,6 +11,7 @@ from pathlib import Path
 from typing import Any
 
 import tiktoken
+from loguru import logger
 
 
 def strip_think(text: str) -> str:
@@ -214,8 +215,8 @@ def maybe_persist_tool_result(
     bucket = ensure_dir(root / safe_filename(session_key or "default"))
     try:
         _cleanup_tool_result_buckets(root, bucket)
-    except Exception:
-        pass
+    except Exception as exc:
+        logger.warning("Failed to clean stale tool result buckets in {}: {}", root, exc)
     path = bucket / f"{safe_filename(tool_call_id)}.{suffix}"
     if not path.exists():
         if suffix == "json" and isinstance(content, list):
diff --git a/tests/agent/test_runner.py b/tests/agent/test_runner.py
index b98550a6d..9009480e3 100644
--- a/tests/agent/test_runner.py
+++ b/tests/agent/test_runner.py
@@ -359,6 +359,32 @@ def test_persist_tool_result_leaves_no_temp_files(tmp_path):
     assert list((root / "current_session").glob("*.tmp")) == []
 
 
+def test_persist_tool_result_logs_cleanup_failures(monkeypatch, tmp_path):
+    from nanobot.utils.helpers import maybe_persist_tool_result
+
+    warnings: list[str] = []
+
+    monkeypatch.setattr(
+        "nanobot.utils.helpers._cleanup_tool_result_buckets",
+        lambda *_args, **_kwargs: (_ for _ in ()).throw(OSError("busy")),
+    )
+    monkeypatch.setattr(
+        "nanobot.utils.helpers.logger.warning",
+        lambda message, *args: warnings.append(message.format(*args)),
+    )
+
+    persisted = maybe_persist_tool_result(
+        tmp_path,
+        "current:session",
+        "call_big",
+        "x" * 5000,
+        max_chars=64,
+    )
+
+    assert "[tool output persisted]" in persisted
+    assert warnings and "Failed to clean stale tool result buckets" in warnings[0]
+
+
 @pytest.mark.asyncio
 async def test_runner_uses_raw_messages_when_context_governance_fails():
     from nanobot.agent.runner import AgentRunSpec, AgentRunner
@@ -392,6 +418,55 @@ async def test_runner_uses_raw_messages_when_context_governance_fails():
     assert captured_messages == initial_messages
 
 
+def test_snip_history_drops_orphaned_tool_results_from_trimmed_slice(monkeypatch):
+    from nanobot.agent.runner import AgentRunSpec, AgentRunner
+
+    provider = MagicMock()
+    tools = MagicMock()
+    tools.get_definitions.return_value = []
+    runner = AgentRunner(provider)
+    messages = [
+        {"role": "system", "content": "system"},
+        {"role": "user", "content": "old user"},
+        {
+            "role": "assistant",
+            "content": "tool call",
+            "tool_calls": [{"id": "call_1", "type": "function", "function": {"name": "ls", "arguments": "{}"}}],
+        },
+        {"role": "tool", "tool_call_id": "call_1", "content": "tool output"},
+        {"role": "assistant", "content": "after tool"},
+    ]
+    spec = AgentRunSpec(
+        initial_messages=messages,
+        tools=tools,
+        model="test-model",
+        max_iterations=1,
+        max_tool_result_chars=_MAX_TOOL_RESULT_CHARS,
+        context_window_tokens=2000,
+        context_block_limit=100,
+    )
+
+    monkeypatch.setattr("nanobot.agent.runner.estimate_prompt_tokens_chain", lambda *_args, **_kwargs: (500, None))
+    token_sizes = {
+        "old user": 120,
+        "tool call": 120,
+        "tool output": 40,
+        "after tool": 40,
+        "system": 0,
+    }
+    monkeypatch.setattr(
+        "nanobot.agent.runner.estimate_message_tokens",
+        lambda msg: token_sizes.get(str(msg.get("content")), 40),
+    )
+
+    trimmed = runner._snip_history(spec, messages)
+
+    assert trimmed == [
+        {"role": "system", "content": "system"},
+        {"role": "assistant", "content": "after tool"},
+    ]
+
+
 @pytest.mark.asyncio
 async def test_runner_keeps_going_when_tool_result_persistence_fails():
     from nanobot.agent.runner import AgentRunSpec, AgentRunner
@@ -614,6 +689,7 @@ async def test_runner_accumulates_usage_and_preserves_cached_tokens():
         tools=tools,
         model="test-model",
         max_iterations=3,
+        max_tool_result_chars=_MAX_TOOL_RESULT_CHARS,
     ))
 
     # Usage should be accumulated across iterations
@@ -652,6 +728,7 @@ async def test_runner_passes_cached_tokens_to_hook_context():
         tools=tools,
         model="test-model",
         max_iterations=1,
+        max_tool_result_chars=_MAX_TOOL_RESULT_CHARS,
         hook=UsageHook(),
     ))
 
diff --git a/tests/providers/test_provider_retry.py b/tests/providers/test_provider_retry.py
index 6b5c8d8d6..1d8facf52 100644
--- a/tests/providers/test_provider_retry.py
+++ b/tests/providers/test_provider_retry.py
@@ -240,3 +240,27 @@ async def test_chat_with_retry_uses_retry_after_and_emits_wait_progress(monkeypa
     assert progress and "7s" in progress[0]
 
 
+@pytest.mark.asyncio
+async def test_persistent_retry_aborts_after_ten_identical_transient_errors(monkeypatch) -> None:
+    provider = ScriptedProvider([
+        *[LLMResponse(content="429 rate limit", finish_reason="error") for _ in range(10)],
+        LLMResponse(content="ok"),
+    ])
+    delays: list[float] = []
+
+    async def _fake_sleep(delay: float) -> None:
+        delays.append(delay)
+
+    monkeypatch.setattr("nanobot.providers.base.asyncio.sleep", _fake_sleep)
+
+    response = await provider.chat_with_retry(
+        messages=[{"role": "user", "content": "hello"}],
+        retry_mode="persistent",
+    )
+
+    assert response.finish_reason == "error"
+    assert response.content == "429 rate limit"
+    assert provider.calls == 10
+    assert delays == [1, 2, 4, 4, 4, 4, 4, 4, 4]
+
+