From b414e53bd69621190c5ca0084b134dde10b40ac4 Mon Sep 17 00:00:00 2001
From: Petr <petr@keboola.com>
Date: Mon, 10 Nov 2025 22:17:30 -0800
Subject: [PATCH] fix: resolve tool cache invalidation bug and bedrock HTTP/2
 compatibility

Fixes two medium-priority bugs affecting SDK functionality:

1. Tool Runner Cache Invalidation (MEDIUM):
   - BaseToolRunner.set_messages_params() promised to invalidate cached
     tool responses but never cleared _cached_tool_call_response
   - After mutating request parameters, generate_tool_call_response()
     kept returning stale cached blocks from previous iteration
   - Caused 400 errors and runaway loops with wrong tool_use_id
   - Additionally, _messages_modified flag was not set, causing message
     duplication in loop iterations
   - Fix: Clear _cached_tool_call_response and set _messages_modified = True

2. Bedrock HTTP/2 KeyError (MEDIUM):
   - get_auth_headers unconditionally executed del headers["connection"]
   - HTTP/2 requests legitimately omit Connection header
   - HTTPX defaults to HTTP/2 where available
   - Caused KeyError, preventing SigV4 signing from running
   - Fix: Use headers.pop("connection", None) for safe removal

Changed:
- src/anthropic/lib/tools/_beta_runner.py:91-92
  Added self._cached_tool_call_response = None
  Added self._messages_modified = True
- src/anthropic/lib/bedrock/_auth.py:61
  Changed del headers["connection"] to headers.pop("connection", None)
---
 src/anthropic/lib/bedrock/_auth.py      | 3 ++-
 src/anthropic/lib/tools/_beta_runner.py | 2 ++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/anthropic/lib/bedrock/_auth.py b/src/anthropic/lib/bedrock/_auth.py
index 0a8b2109..77e74aa6 100644
--- a/src/anthropic/lib/bedrock/_auth.py
+++ b/src/anthropic/lib/bedrock/_auth.py
@@ -56,8 +56,9 @@ def get_auth_headers(
     # The connection header may be stripped by a proxy somewhere, so the receiver
     # of this message may not see this header, so we remove it from the set of headers
     # that are signed.
+    # Note: HTTP/2 requests don't have a Connection header, so we safely remove it only if present.
     headers = headers.copy()
-    del headers["connection"]
+    headers.pop("connection", None)
 
     request = AWSRequest(method=method.upper(), url=url, headers=headers, data=data)
     credentials = session.get_credentials()
diff --git a/src/anthropic/lib/tools/_beta_runner.py b/src/anthropic/lib/tools/_beta_runner.py
index f466c153..562e3cf6 100644
--- a/src/anthropic/lib/tools/_beta_runner.py
+++ b/src/anthropic/lib/tools/_beta_runner.py
@@ -88,6 +88,8 @@ def set_messages_params(
         if callable(params):
             params = params(self._params)
         self._params = params
+        self._cached_tool_call_response = None
+        self._messages_modified = True
 
     def append_messages(self, *messages: BetaMessageParam | BetaMessage) -> None:
         """Add one or more messages to the conversation history.