Fix: resolve pre-commit issues and add missing annotations

Author: Liu Keyu

src/mqt/predictor/rl/actions.py

@@ -46,7 +46,7 @@
 )
 from qiskit.passmanager import ConditionalController
 from qiskit.transpiler import (
-    CouplingMap,
+    CouplingMap, Target
 )
 from qiskit.transpiler.passes import (
     ApplyLayout,
@@ -126,6 +126,7 @@ class Action:
     transpile_pass: (
         list[qiskit_BasePass | tket_BasePass]
         | Callable[..., list[qiskit_BasePass | tket_BasePass]]
+        | Callable[[Target, tuple[int, int]], list[qiskit_BasePass | tket_BasePass]]
         | Callable[
             ...,
             Callable[..., tuple[Any, ...] | Circuit],

src/mqt/predictor/rl/helper.py

@@ -20,14 +20,16 @@
 from qiskit.circuit import ClassicalRegister, QuantumRegister, Instruction, Qubit
 from qiskit.transpiler import PassManager, Target
 from qiskit.dagcircuit import DAGCircuit
-from qiskit_ibm_transpiler.ai.routing import AIRouting 
 
 from mqt.predictor.utils import calc_supermarq_features
 from mqt.predictor.rl.actions import Action
 
 if TYPE_CHECKING:
     from numpy.random import Generator
     from numpy.typing import NDArray
+    from qiskit_ibm_transpiler.ai.routing import AIRouting
+else:
+    AIRouting = object # type: ignore[misc]
 
 import zipfile
 from importlib import resources
@@ -103,7 +105,7 @@ def add_cregs_and_measurements(
         qc.append(instr, new_qargs, cargs)
     return qc
 
-class SafeAIRouting(AIRouting):
+class SafeAIRouting(AIRouting): # type: ignore[misc]
     """
     Custom AIRouting wrapper that removes classical registers before routing.
 
@@ -137,9 +139,15 @@ def run(self, dag: DAGCircuit) -> DAGCircuit:
 
         qubit_map = {}
         for virt in qc_orig.qubits:
-            phys = final_layout[virt]
+            try:
+                phys = final_layout[virt]  # This is now safe due to above check
+            except KeyError as err:
+                raise RuntimeError(f"Virtual qubit {virt} not found in final layout!") from err
             if isinstance(phys, int):
-                qubit_map[virt] = qc_routed.qubits[phys]
+                try:
+                    qubit_map[virt] = qc_routed.qubits[phys]
+                except IndexError as err:
+                    raise RuntimeError(f"Physical index {phys} is out of range in routed circuit!") from err
             else:
                 try:
                     idx = qc_routed.qubits.index(phys)
@@ -183,6 +191,8 @@ def best_of_n_passmanager(
     else:
         all_passes = action.transpile_pass(device)
 
+    assert isinstance(all_passes, list)
+
     layout_passes = all_passes[:-1]
     routing_pass = all_passes[-1:]
 

src/mqt/predictor/rl/predictorenv.py

@@ -361,7 +361,7 @@ def metric_fn(circ: QuantumCircuit) -> float:
         return altered_qc
 
     def _handle_qiskit_layout_postprocessing(
-        self, action: Action, pm_property_set: dict, altered_qc: QuantumCircuit, 
+        self, action: Action, pm_property_set: dict[str, any], altered_qc: QuantumCircuit, 
     ) -> QuantumCircuit:
         if action.name == "VF2PostLayout":
             assert pm_property_set["VF2PostLayout_stop_reason"] is not None
@@ -379,7 +379,7 @@ def _handle_qiskit_layout_postprocessing(
                 _output_qubit_list=altered_qc.qubits,
                 _input_qubit_count=self.num_qubits_uncompiled_circuit,
             )
-        if pm_property_set["final_layout"]:
+        if self.layout is not None and pm_property_set["final_layout"]:
             self.layout.final_layout = pm_property_set["final_layout"]
         return altered_qc