Summary

When auto-compaction fires during a context overflow, the retry can immediately overflow again because the compaction summary + original prompt exceed the context window. This creates a cascade loop: overflow → compact → retry → overflow → compact → retry.

Expected Behavior

After compaction, the retry should use a slim prompt that fits within the remaining budget, preventing the cascade.

Actual Behavior

The retry reuses the full original prompt, which may exceed the post-compaction context budget, triggering another compaction immediately.

Fix

PR #10220 implements a compaction retry hook that:

• Intercepts the retry before it fires
• Calculates a safe token budget
• Downgrades the prompt to a slim one-shot version if needed
• Cancels the retry if even the slim prompt won't fit

Depends on setAutoCompactionRetryHook being exposed by pi-coding-agent (PR badlogic/pi-mono#1318).