Anthropic SDK for Python 1.2

Apply the Python 3 baseline first. These rules cover Anthropic SDK for Python 1.2 credentials, Messages API construction, tool use, streaming, files, retries, errors, and production controls.

Client and credentials

• Construct Anthropic clients from server-side secrets or a workload secret provider and never expose API keys to browsers or mobile clients.
• Keep base_url, proxy, custom transport, credential profiles, middleware, and default-header settings fixed in trusted configuration; restrict extra_body, extra_query, extra_headers, and with_options() so request overrides cannot bypass these controls or replace Host and authentication headers.
• For Anthropic and AsyncAnthropic model, Files, batch, and other SDK API requests, allow only reviewed HTTPS scheme/host/port destinations for base_url and only explicitly approved proxy endpoints, including any intentionally used internal proxy. Review ANTHROPIC_BASE_URL, credential-profile URLs, HTTP_PROXY/HTTPS_PROXY/ALL_PROXY/NO_PROXY, httpx2 mounts, with_options(), and caller-supplied http_client against the same policy.
• Enforce the SDK request policy in the sync and async transport, egress proxy, and network controls: for each direct connection, resolve the destination and connect only to an approved address while retaining TLS hostname verification; reject loopback, private, link-local, multicast, and metadata addresses. Check an approved internal proxy's exact endpoint, require it to enforce the upstream destination and resolved-address policy, and block routes that bypass it.