Three small extractions into focused modules:
* agent/process_bootstrap.py — \_OpenAIProxy (lazy openai.OpenAI import),
\_SafeWriter (broken-pipe-resistant stdio wrapper), \_install_safe_stdio,
\_get_proxy_from_env, \_get_proxy_for_base_url. All process / IO bootstrap.
* agent/iteration_budget.py — IterationBudget class (thread-safe consume/
refund counter shared by parent agent and subagents).
run_agent re-exports every name so existing test patches like
patch('run_agent.OpenAI', ...) and 'from run_agent import IterationBudget'
keep working unchanged. Verified the patch-rebinding contract for OpenAI
explicitly.
tests/run_agent/ + tests/agent/test_gemini_fast_fallback.py:
1347 passed, 3 skipped.
run_agent.py: 15427 -> 15261 lines (-166).