## Summary
- read the `AutoCompaction` feature flag through `TurnContext::config`
- fix both the mid-turn and pre-sampling compaction checks
## Why
#28260 was validated against an older base where `TurnContext` exposed a
direct `features` field. It was then merged after that field had moved
under `config`, leaving the merge result unable to compile with `E0609`
on `turn_context.features`.
This restores compilation for Bazel, SDK, and argument-comment-lint jobs
that build `codex-core`. Behavior is unchanged: disabling
`auto_compaction` still skips automatic compaction.
## Validation
- `just fmt`
- `CODEX_HOME=/private/tmp/codex-fix-auto-compaction-test-home just test
-p codex-core auto_compaction_feature_disabled` — 4 passed
- `just test -p codex-core` — `codex-core` compiled; 2,722 passed and 89
unrelated local-environment failures remained because the sandbox could
not write the default Codex SQLite/proxy paths and some first-party test
binaries were unavailable
sayan-oaiandGitHub
98845e4840