python-sdk: use pinned runtime package in real coverage (2026-03-12)

2026-03-12

Switch the repo-source Python SDK real coverage over to a pinned runtime-package flow backed by GitHub release artifacts instead of PATH or explicit binary overrides.

- add sdk/python/_runtime_setup.py to download the release codex archive for a requested CODEX_PYTHON_RUNTIME_VERSION, stage a temporary codex-cli-bin package, and install it into a target Python environment with cleanup
- refactor real integration tests to run repo-source SDK code against an isolated site-packages target that contains the staged codex-cli-bin runtime
- update examples and notebook bootstrap to install and use the runtime package, and stop consulting CODEX_PYTHON_SDK_CODEX_BIN or PATH
- switch the failing turn-run and model-selection examples to runtime-compatible model selection for the pinned release binary
- keep the main SDK runtime resolution model unchanged: explicit codex_bin or installed codex-cli-bin

Validation:
- python3 -m pytest sdk/python/tests
- RUN_REAL_CODEX_TESTS=1 CODEX_PYTHON_RUNTIME_VERSION=0.115.0-alpha.11 python3 -m pytest sdk/python/tests/test_real_app_server_integration.py

Co-authored-by: Codex <noreply@openai.com>

sdk/python/examples/02_turn_run/sync.py

@@ -12,7 +12,7 @@ ensure_local_sdk_src()
 from codex_app_server import Codex, TextInput
 
 with Codex(config=runtime_config()) as codex:
-    thread = codex.thread_start(model="gpt-5", config={"model_reasoning_effort": "high"})
+    thread = codex.thread_start(model="gpt-5.4", config={"model_reasoning_effort": "high"})
     result = thread.turn(TextInput("Give 3 bullets about SIMD.")).run()
 
     print("thread_id:", result.thread_id)