# 0.20.0 - 2026-06-23

## Deprecated

- The default value for the inject noise site for the `generate_boxing_pass_manager`, `AddInjectNoise`, and `InjectNoise` has been updated from `'before'` to `None`, which results in a future warning and sets the value to `'before'`. In a future release, the default will be updated to `'after'`. ([#372](https://github.com/Qiskit/samplomatic/issues/372))

## Added

- Added support for propagating Pauli twirls past single-qubit Clifford gates (`s`, `sx`, `sdg`, `sxdg`, and compositions with `h`) and through single-qubit rotations (`rz`, `p`, `rx`) at Clifford angles when they appear between entangling gates inside a `Twirl` box. ([#351](https://github.com/Qiskit/samplomatic/issues/351))
- Exposed three primitives that together let consumers of `build()` evaluate deterministic template parameters (e.g., `RZZ` angles) without invoking `Samplex.sample`:

  - `Samplex.param_table` — return the underlying `ParameterExpressionTable`.
  - `Samplex.passthrough_params` — a tuple `(template_idxs, expression_idxs)` mapping each passthrough template parameter to its expression-table index.
  - `ParameterExpressionTable.evaluate` — gained an optional `indices` argument so callers can evaluate only a chosen subset of the table's expressions.

  ([#367](https://github.com/Qiskit/samplomatic/issues/367))
- Random phases are now applied to qubits after mid-circuit measurement twirling. ([#369](https://github.com/Qiskit/samplomatic/issues/369))
- Added reset twirling. Rather than propagating virtual registers, a reset in a twirl‑annotated box discards them and instead samples and injects a new random phase following the reset. ([#371](https://github.com/Qiskit/samplomatic/issues/371))

## Changed

- Twirl emissions are now inserted at the easy-hard boundary of boxes with a `Twirl` annotation `"left"` dressing when building.
  Previously, they were inserted after the content of the box. ([#368](https://github.com/Qiskit/samplomatic/issues/368))

## Improved

- Measurement twirling is now implemented using virtual gate propagation. A virtual Pauli is propagated past a measure by discarding its `z` component, while propagating its `x` component and recording it as a bit flip. Previously, measurement twirling was implemented by collecting bit flips associated with virtual gates exclusively in the right hand side of a left-dressed box. The new approach allows for more flexible measurement twirling, e.g., sequential measurements of the same qubit to different clbits in the same box and measurement twirling in right-dressed boxes. ([#369](https://github.com/Qiskit/samplomatic/issues/369))
- Removed the restriction of having a single entangler type when using `Group.local_c1`. ([#370](https://github.com/Qiskit/samplomatic/issues/370))

## Fixed

- Fixed an issue when using `GroupMode.local_pauli` twirling where the fallback for Clifford gates to the Pauli group would not trigger when a fractional gate was also present. ([#370](https://github.com/Qiskit/samplomatic/issues/370))
- Fixed a bug where untwirled measurements in annotated boxes did not block leftwards virtual gate propagation. ([#373](https://github.com/Qiskit/samplomatic/issues/373))