Since you lived with this for such a long stretch, I'd love your gut reaction to the specific escape hatches I'm building in to avoid the rigidity trap:

1. Arenas grow, not fixed:

Unlike stack frames, the arenas in my model can expand dynamically. So it's not "size for worst case"—it's "grow as needed, free all at once when scope ends." A request handler that processes 10 items or 10,000 items uses the same code; the arena just grows.

2. Handles for non-hierarchical references

When data genuinely needs to outlive its lexical scope or be shared across the hierarchy, you get a generational handle:

    let handle = app_cache.store(expensive_result)
    // handle can be passed around, stored, retrieved later
    // data lives in app scope, not request scope

3. Explicit clone for escape:

If you need to return data from an inner scope to an outer one, you say `clone()` and it copies to the caller's arena. Not automatic, but not forbidden either.

4. The hierarchy matches server reality:

    App (config, pools, caches)
    └── Worker (thread-local state)
        └── Task (single request)
            └── Frame (loop iteration)

Where I think it still gets awkward:

* Graph structures with cycles (need handles, less ergonomic than GC)

* FFI with libraries expecting malloc/free (planning an `unmanaged` escape hatch)

* Long-running mutations without periodic scope resets (working on incremental reclamation)

Do you think this might address the pain you experienced, or am I missing something? Particularly curious whether the handle mechanism would have helped with the cases where you had to hammer code into the hierarchy.