Move _interruptible_streaming_api_call out of run_agent.py — the biggest
single method in the file. Body lives next to interruptible_api_call
in agent/chat_completion_helpers.py so streaming + non-streaming code
share one home.
Nested closures (_call_chat_completions, _call_anthropic, the codex
stream branch) all come along with the body and still capture the
parent function's locals as expected.
AIAgent keeps a thin forwarder method. is_local_endpoint added to
the import block (used by the stream stale-timeout disable logic).
One source-introspection test in TestAnthropicInterruptHandler is
updated to scan agent.chat_completion_helpers.interruptible_streaming_api_call
instead of AIAgent._interruptible_streaming_api_call.
tests/run_agent/ + tests/agent/: 4312 passed (same pre-existing
test_auxiliary_client failure).
run_agent.py: 12277 -> 11385 lines (-892).