I want to define a `Subcircuit` as a combination of `Interval`s on
resource paths (the parts with linear, non-copyable data), and ASTs of
fully classical, copyable data.

- PR #1205 was opened to refine the notion of `Interval`
- this PR creates the `CopyableExpressionAST` type that corresponds to
ASTs of classical data in hugr graphs.

---------

Co-authored-by: Alan Lawrence <[email protected]>

## 🤖 New release

* `tket`: 0.16.0 -> 0.17.0 (✓ API compatible changes)
* `tket-qsystem`: 0.22.0 -> 0.23.0 (✓ API compatible changes)

<details><summary><i><b>Changelog</b></i></summary><p>

## `tket`

<blockquote>

##
[0.17.0](tket-v0.16.0...tket-v0.17.0)
- 2026-02-02

### Bug Fixes

- *(encoded-circ)* Track unsupported wires between input and output
([#1224](#1224))
- Multiple fixes to the pytket encoder
([#1226](#1226))
- Don't use opgroup in pytket barrier encoding
([#1251](#1251))
- guppy_to_circuit always returns num_operations = 0
([#1200](#1200))
- *(pytket-decoder)* Avoid QAllocating and immediately freeing qubits
([#1256](#1256))
- Encoding of opaque subgraphs with no associated qubit/bit
([#1295](#1295))
- [**breaking**] Don't rely on command params for pytket barriers
([#1298](#1298))
- Track output qubits in CircuitInfo
([#1304](#1304))
- Wrongly reused qubit IDs in pytket encoding
([#1358](#1358))

### New Features

- Deprecate local find_tuple_unpack rewrite
([#1188](#1188))
- Add CopyableExpressionAST
([#1209](#1209))
- `NormalizeGuppy` pass to simplify generated structure
([#1220](#1220))
- [**breaking**] pytket EncodedCircuit struct for in-place pytket
optimisation ([#1211](#1211))
- [**breaking**] Interval is independent of resource IDs and scope
position ([#1205](#1205))
- Don't translate usizes to pytket
([#1241](#1241))
- BorrowSquashPass to elide redundant borrow/return ops
([#1159](#1159))
- [**breaking**] Bump hugr to 0.25.0
([#1325](#1325))
- Remove order edges in NormalizeGuppy pass
([#1326](#1326))
- [**breaking**] Remove deprecated unpack tuple pass
([#1387](#1387))

### Refactor

- Remove contain_qubits, use TypeUnpacker
([#1283](#1283))
- [**breaking**] Replace Subcircuit with SiblingSubgraph
([#1288](#1288))
- *(metadata)* [**breaking**] Migrate all metadata keys onto the new
metadata traits ([#1328](#1328))
</blockquote>

## `tket-qsystem`

<blockquote>

##
[0.23.0](tket-qsystem-v0.22.0...tket-qsystem-v0.23.0)
- 2026-02-02

### Bug Fixes

- [**breaking**] Don't rely on command params for pytket barriers
([#1298](#1298))
- Wrongly reused qubit IDs in pytket encoding
([#1358](#1358))

### New Features

- `NormalizeGuppy` pass to simplify generated structure
([#1220](#1220))
- Allow running arbitrary serializable pytket passes on hugrs
([#1266](#1266))
- BorrowSquashPass to elide redundant borrow/return ops
([#1159](#1159))
- [**breaking**] Bump hugr to 0.25.0
([#1325](#1325))
- Remove order edges in NormalizeGuppy pass
([#1326](#1326))
- hide new public funcs introduced by linearization
([#1333](#1333))

### Testing

- regenerate guppy_opt examples, and count gates
([#1249](#1249))
- run pytket on guppy_opt tests, measure (very limited) success
([#1250](#1250))
</blockquote>


</p></details>

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