Auto-compact fails

### Steps to reproduce

1. Start a long, multi-turn diagnostic conversation.
2. Accumulate many context-heavy messages (commands/results/analysis).
3. When context window is near limit, continue with another query.
4. Observe hard error asking to start new thread / clear history instead of graceful summarization.

### Expected behavior

• Before hard cutoff, Codex should trigger automatic context compression (or offer an explicit “compress and continue” option).
• It should preserve key context (e.g., session goal, environment state, diagnostic findings, IDs, executed commands).
• Conversation should continue without requiring manual new-thread handoff.

### Actual behavior

• No auto-compression observed.
• Session abruptly stops with context window error.
• User must manually start a new thread or clear history, interrupting troubleshooting flow.