Anthropic SDK for Python 1.4

Apply the Python 3 baseline first, then these rules for applications built on the anthropic package 1.4 release line. Version 1.4 requires Python 3.10 or later and uses httpx2, not the separate httpx package. Treat prompts, retrieved content, tool results, model text, tool arguments, generated files, and agent state as untrusted across every API and worker boundary.

Version and dependency boundary

• Lock anthropic and its transitive dependencies in the lock file, check at startup that anthropic.__version__ matches the locked release, and record it in deployment evidence. Anthropic ships fixes and hardening such as stricter credential-file checks in new 1.x releases rather than as patches to earlier minors, so taking one means moving to a newer release and re-reviewing these rules against it.
• Run on a CPython minor that still receives security fixes; 1.4 still installs on 3.10, which reached end of life on 2026-10-01. Test the exact interpreter you deploy rather than relying on the package classifiers through Python 3.14 as proof of compatibility.
• Import transports, timeouts, and custom clients from httpx2; do not pass an object from the distinct httpx package as http_client.
• Call httpx2.alias_httpx() only when a reviewed tracing or mocking integration genuinely needs the alias, and prove that it does not record API keys, prompts, files, or responses.
• Remove legacy Text Completions calls and the deleted Messages sampling parameters temperature, top_p, and top_k when migrating to 1.x.
• Replace output_format arguments containing schema