📬 Issue #, if available:

Closes #264

✍️ Description of changes:

Summary

CounterGuard borrows &'a AtomicU64, which prevents it from being stored in structs that outlive the borrow (e.g. response body wrappers in tower middleware). Users currently fall back to manual fetch_add/fetch_sub, losing RAII safety.

This adds OwnedCounterGuard, which holds an Arc<Counter> instead of a reference. It has the same Drop behavior (saturating decrement) and the same CloseValue impls as CounterGuard, but can be freely moved across async boundaries.
a📬 Issue #, if available:

Closes #264

✍️ Description of changes:

Summary

CounterGuard borrows &'a AtomicU64, which prevents it from being stored in structs that outlive the borrow (e.g. response body wrappers in tower middleware). Users currently fall back to manual fetch_add/fetch_sub, losing RAII safety.

This adds OwnedCounterGuard, which internally shares the counter and can be freely moved across async boundaries. It has the same Drop behavior (saturating decrement) and the same CloseValue impls as CounterGuard.

The guard is Clone. Cloning shares the underlying counter without incrementing it; each clone independently decrements on drop. Callers are responsible for ensuring the counter has been incremented a corresponding number of times.

The constructor is Counter::increment_scoped_owned(self: &Arc<Self>), mirroring the existing Counter::increment_scoped(&self) API.

OwnedCounterGuard is re-exported from both metrique-core and the top-level metrique crate.

Testing

Unit tests covering increment/drop semantics, saturation at zero, CloseValue behavior, cross-thread movement, and multiple concurrent guards on the same counter.

🔏 By submitting this pull request

• I confirm that I've made a best effort attempt to update all relevant documentation.
• I confirm that my contribution is made under the terms of the Apache 2.0 license.
  The constructor is Counter::increment_scoped_owned(self: &Arc<Self>), mirroring the existing Counter::increment_scoped(&self) API. The caller wraps their Counter in an Arc, which is the natural choice for shared state in async contexts.

OwnedCounterGuard is re-exported from both metrique-core and the top-level metrique crate.

Testing

Unit tests covering increment/drop semantics, saturation at zero, CloseValue behavior, cross-thread movement, and multiple concurrent guards on the same counter.

🔏 By submitting this pull request

• I confirm that I've made a best effort attempt to update all relevant documentation.
• I confirm that my contribution is made under the terms of the Apache 2.0 license.