diff --git a/strix/llm/llm.py b/strix/llm/llm.py
index 4f624956a..5cabf227e 100644
--- a/strix/llm/llm.py
+++ b/strix/llm/llm.py
@@ -1,4 +1,5 @@
 import asyncio
+import re
 from collections.abc import AsyncIterator
 from dataclasses import dataclass
 from typing import Any
@@ -26,6 +27,12 @@
 litellm.modify_params = True
 
 
+_TOOL_RESULT_PATTERN = re.compile(
+    r"(<tool_result>\s*<tool_name>[^<]*</tool_name>\s*<result>)(.*?)(</result>\s*</tool_result>)",
+    re.DOTALL,
+)
+
+
 class LLMRequestFailedError(Exception):
     def __init__(self, message: str, details: str | None = None):
         super().__init__(message)
@@ -159,12 +166,33 @@ async def generate(
         messages = self._prepare_messages(conversation_history)
         max_retries = int(Config.get("strix_llm_max_retries") or "5")
 
+        bad_request_retried = False
+
         for attempt in range(max_retries + 1):
             try:
                 async for response in self._stream(messages):
                     yield response
                 return  # noqa: TRY300
             except Exception as e:  # noqa: BLE001
+                if self._is_bad_request(e):
+                    if not bad_request_retried:
+                        bad_request_retried = True
+                        if attempt >= max_retries:
+                            self._raise_error(e)
+                        await asyncio.sleep(2)
+                        continue
+                    truncate_enabled = Config.get("strix_truncate_on_oversize") or ""
+                    if (
+                        truncate_enabled.lower() in ("1", "true", "yes")
+                        and self._truncate_large_tool_results(messages)
+                    ):
+                        if attempt >= max_retries:
+                            self._raise_error(e)
+                        # Pace the provider — matches the 2s sleep on the bare-retry
+                        # path so a throttled provider isn't hit back-to-back after the
+                        # original 400.
+                        await asyncio.sleep(2)
+                        continue
                 if attempt >= max_retries or not self._should_retry(e):
                     self._raise_error(e)
                 wait = min(90, 2 * (2**attempt))
@@ -314,6 +342,60 @@ def _extract_cost(self, response: Any) -> float:
         except Exception:  # noqa: BLE001
             return 0.0
 
+    @staticmethod
+    def _truncate_large_tool_results(
+        messages: list[dict[str, Any]],
+        threshold_chars: int = 2000,
+        truncate_to_chars: int = 1000,
+    ) -> bool:
+        """Truncate large tool_result XML blocks to recover from BadRequestError.
+
+        Scans all messages for tool_result blocks whose body exceeds threshold_chars
+        and shrinks them to truncate_to_chars. Called repeatedly on each 400 until it
+        returns False (nothing left to truncate).
+
+        threshold_chars and truncate_to_chars are independent: the threshold decides
+        which blocks qualify for truncation, and truncate_to_chars is the size of the
+        retained prefix. They are not the same value to allow aggressive shrinking of
+        blocks that are well over the threshold without re-processing blocks that are
+        already acceptable.
+        """
+        truncated_any = False
+
+        def _truncate_match(m: re.Match) -> str:
+            nonlocal truncated_any
+            prefix, body, suffix = m.group(1), m.group(2), m.group(3)
+            if len(body) <= threshold_chars:
+                return m.group(0)
+            truncated_any = True
+            kept = body[:truncate_to_chars]
+            return (
+                f"{prefix}{kept}\n\n... [content truncated from {len(body)} to {len(kept)} chars "
+                f"due to request size limit — file requires manual review] ...{suffix}"
+            )
+
+        for msg in reversed(messages):
+            content = msg.get("content")
+
+            if isinstance(content, list):
+                for block in content:
+                    if (
+                        block.get("type") == "text"
+                        and isinstance(block.get("text"), str)
+                        and "<tool_result>" in block["text"]
+                    ):
+                        block["text"] = _TOOL_RESULT_PATTERN.sub(_truncate_match, block["text"])
+            elif isinstance(content, str) and "<tool_result>" in content:
+                msg["content"] = _TOOL_RESULT_PATTERN.sub(_truncate_match, content)
+
+        return truncated_any
+
+    def _is_bad_request(self, e: Exception) -> bool:
+        code = getattr(e, "status_code", None) or getattr(
+            getattr(e, "response", None), "status_code", None
+        )
+        return code == 400
+
     def _should_retry(self, e: Exception) -> bool:
         code = getattr(e, "status_code", None) or getattr(
             getattr(e, "response", None), "status_code", None