fix(databricks): read the thinking signature with get to satisfy the type checker

thinking_blocks is a union that includes ChatCompletionRedactedThinkingBlock,
which has no signature key, so subscripting it tripped
reportGeneralTypeIssues and breached the basedpyright budget. The filter
already guarantees the key is present.

litellm/llms/databricks/chat/transformation.py

@@ -502,7 +502,7 @@ class DatabricksConfig(DatabricksBase, OpenAILikeChatConfig, AnthropicConfig):
         holds_reasoning: Final = any(isinstance(b, dict) and b.get("type") == "reasoning" for b in existing)
         replace: Final = signed is not None and not holds_reasoning and bool(existing)
         text: Final = (signed.get("thinking") or "") if signed is not None else ""
-        signature: Final = signed["signature"] if signed is not None else ""
+        signature: Final = (signed.get("signature") or "") if signed is not None else ""
         entry: Final = {"type": "summary_text", "text": text, "signature": signature}  # mutable-ok: provider JSON
         block: Final = {"type": "reasoning", "summary": [entry]}  # mutable-ok: outbound provider JSON
         rebuilt: Final = {**stripped, "content": [block, *existing]}  # mutable-ok: outbound provider JSON

tests/test_litellm/llms/databricks/chat/test_databricks_chat_transformation.py

@@ -496,6 +496,8 @@ def test_chunk_parser_without_usage_still_parses_content():
     assert result.id == "chatcmpl-test"
     assert result.model == "databricks-claude-sonnet-5"
     assert result.choices[0]["delta"]["content"] == "hi"
+
+
 def _thinking_message(thinking_blocks, content="391"):
     return {"role": "assistant", "content": content, "thinking_blocks": thinking_blocks}