"""LintQ detector stub -- auto-scaffolded from research note.

Generated by detector_stub_cron.py for cluster 41
(label: Qiskit:numeric-stability).

Source note (#26): PATTERN: Numerical-accuracy regressions in unitary/state construction that accumulate error with qubit count. 1 issue(s) across: Qiskit. Sample: Open GitHub issue #16689 in Qiskit/qiskit reported by @Giacomo-Antonioli: StatePreparation uni…
"""

from __future__ import annotations

from typing import Dict, List


class DetectorNumericStability:
    """Detect the 'numeric-stability' anti-pattern reported against Qiskit.

    STATUS: STUB. This class was scaffolded automatically from a real issue
    cluster in lintq_research.db. Fill in ``detect`` with the logic below and
    add it to the engine rule set.

    TODO -- implement the detection:
        PATTERN: Numerical-accuracy regressions in unitary/state construction that accumulate error with qubit count. 1 issue(s) across: Qiskit. Sample: Open GitHub issue #16689 in Qiskit/qiskit reported by @Giacomo-Antonioli: StatePreparation unitary matrix composition accumulates exponential $L_2$ error as qub

        DETECTION LOGIC: Add a LintQ detector 'unitary-composition-error' that instruments state/unitary builders to track cumulative frobenius/L2 error of intermediate compositions and emits a warning when error growth is super-linear in qubit count. Hook into StatePreparation / operator composition paths; threshold on measured ||U_exact - U_built||_2.
    """

    id = "numeric_stability"
    theme = "numeric-stability"
    software = "Qiskit"
    cluster_id = 41
    note_id = 26

    def detect(self, facts: Dict) -> List[Dict]:
        """Return a list of warning dicts for the given extracted facts.

        Args:
            facts: the 7-relation EDB fact dict produced by the extractor
                (Stmt, CFGEdge, Assign, CircuitAlloc, GateOp, MeasureOp,
                CircuitCall).

        Returns:
            A list of warning dicts, e.g.
            {"kind": "numeric_stability", "stmt": <id>, "qubit": <q>, "detail": <str>}.
        """
        raise NotImplementedError(
            "Detector stub -- implement 'numeric-stability' detection for Qiskit. "
            "See the TODO block in this class for the source note's logic."
        )