diff --git a/pr_agent/algo/__init__.py b/pr_agent/algo/__init__.py
index 7cb13517..27af6af7 100644
--- a/pr_agent/algo/__init__.py
+++ b/pr_agent/algo/__init__.py
@@ -79,7 +79,7 @@
     'anthropic/claude-3-5-sonnet-20240620': 100000,
     'anthropic/claude-3-5-sonnet-20241022': 100000,
     'anthropic/claude-3-7-sonnet-20250219': 200000,
-    'claude-3-7-sonnet-20250219': 200000,
+    'anthropic/claude-sonnet-4-20250514': 1000000,
     'anthropic/claude-3-5-haiku-20241022': 100000,
     'bedrock/anthropic.claude-instant-v1': 100000,
     'bedrock/anthropic.claude-v2': 100000,
@@ -167,7 +167,7 @@
 
 CLAUDE_EXTENDED_THINKING_MODELS = [
     "anthropic/claude-opus-4-20250514",
-    "anthropic/claude-sonnet-4-20250514", 
+    "anthropic/claude-sonnet-4-20250514",
     "anthropic/claude-3-7-sonnet-20250219",
     "claude-3-7-sonnet-20250219"
 ]
diff --git a/pr_agent/algo/ai_handlers/litellm_ai_handler.py b/pr_agent/algo/ai_handlers/litellm_ai_handler.py
index 0cf487f3..7e70428d 100644
--- a/pr_agent/algo/ai_handlers/litellm_ai_handler.py
+++ b/pr_agent/algo/ai_handlers/litellm_ai_handler.py
@@ -426,7 +426,7 @@ async def chat_completion(self, model: str, system: str, user: str, temperature:
             if self.repetition_penalty:
                 kwargs["repetition_penalty"] = self.repetition_penalty
 
-            #Added support for extra_headers while using litellm to call underlying model, via a api management gateway, would allow for passing custom headers for security and authorization
+            # Added support for extra_headers while using litellm to call underlying model, via a api management gateway, would allow for passing custom headers for security and authorization
             if get_settings().get("LITELLM.EXTRA_HEADERS", None):
                 try:
                     litellm_extra_headers = json.loads(get_settings().litellm.extra_headers)
@@ -434,7 +434,22 @@ async def chat_completion(self, model: str, system: str, user: str, temperature:
                         raise ValueError("LITELLM.EXTRA_HEADERS must be a JSON object")
                 except json.JSONDecodeError as e:
                     raise ValueError(f"LITELLM.EXTRA_HEADERS contains invalid JSON: {str(e)}")
-                kwargs["extra_headers"] = litellm_extra_headers
+                # Merge with any pre-existing headers
+                merged_headers = dict(kwargs.get("extra_headers", {}))
+                merged_headers.update(litellm_extra_headers)
+                kwargs["extra_headers"] = merged_headers
+
+            # Ensure Anthropic 1M-context beta is enabled for relevant Claude models (not Bedrock)
+            try:
+                if (
+                    ("claude" in model.lower() or model.lower().startswith("anthropic/"))
+                    and not model.lower().startswith("bedrock/")
+                ):
+                    headers = dict(kwargs.get("extra_headers", {}))
+                    headers.setdefault("anthropic-beta", "context-1m-2025-08-07")
+                    kwargs["extra_headers"] = headers
+            except Exception as e:
+                get_logger().debug(f"Unable to set Anthropic beta header: {e}")
 
             get_logger().debug("Prompts", artifact={"system": system, "user": user})