- Add CachedListModels() with 24h TTL to avoid repeated Models() API calls
- Cache readdir serialized bytes per-fid (rebuild only at offset=0)
- Skip all session file size computation in makeStat (report len=0)
- Short-circuit pathType() for session paths to avoid triggering Stat
- Remove e.Info() call from subdirectory readdir (unused mtime)
- Add monotonic timer to handle() for profiling 9p operations
- Add fcallTypeName() helper
- Fix stubCore for new Detach/SaveSession interface methods
- Add tools-process.md prompt
Before: ls inside a session dir took 1.38s (kiro) / 67ms (openrouter)
After: 182µs regardless of backend (7500x improvement)
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