Fix lint and remove section comment banners

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: Transurgeon

cvxpy/reductions/solvers/nlp_solvers/diff_engine/converters.py

@@ -20,24 +20,17 @@
 
 import cvxpy as cp
 from cvxpy.expressions.constants.parameter import Parameter
-
 from cvxpy.reductions.solvers.nlp_solvers.diff_engine.helpers import (
     _make_dense_left_matmul,
     _make_dense_right_matmul,
     _make_sparse_left_matmul,
     _make_sparse_right_matmul,
     _to_dense_float,
-    build_param_dict,
-    build_var_dict,
     normalize_shape,
 )
 from cvxpy.reductions.solvers.nlp_solvers.diff_engine.registry import ATOM_CONVERTERS
 
 
-# ---------------------------------------------------------------------------
-# Matmul / multiply converters (need param_dict for parameter support)
-# ---------------------------------------------------------------------------
-
 def _convert_matmul(expr, children, var_dict, n_vars, param_dict):
     """Convert matrix multiplication A @ f(x), f(x) @ A, or X @ Y."""
     left_arg, right_arg = expr.args
@@ -106,9 +99,6 @@ def _convert_multiply(expr, children, var_dict, n_vars, param_dict):
     return _diffengine.make_multiply(children[0], children[1])
 
 
-# ---------------------------------------------------------------------------
-# Main conversion entry point
-# ---------------------------------------------------------------------------
 
 def convert_expr(expr, var_dict, n_vars, param_dict=None):
     """Convert a CVXPY expression to a C diff engine expression.

cvxpy/reductions/solvers/nlp_solvers/diff_engine/helpers.py

@@ -41,9 +41,6 @@ def _chain_add(children):
     return result
 
 
-# ---------------------------------------------------------------------------
-# Matmul helpers (handle param_node insertion for SparseDiffPy API)
-# ---------------------------------------------------------------------------
 
 def _make_sparse_left_matmul(param_node, child, A):
     if not isinstance(A, sparse.csr_matrix):
@@ -79,9 +76,6 @@ def _make_dense_right_matmul(param_node, child, A):
         param_node, child, A.flatten(order='C'), m, n)
 
 
-# ---------------------------------------------------------------------------
-# Variable / parameter dict builders
-# ---------------------------------------------------------------------------
 
 def build_var_dict(inverse_data):
     """Build {var_id: C variable capsule} mapping from InverseData."""

cvxpy/reductions/solvers/nlp_solvers/diff_engine/registry.py

@@ -24,7 +24,6 @@
 from sparsediffpy import _sparsediffengine as _diffengine
 
 import cvxpy as cp
-
 from cvxpy.reductions.solvers.nlp_solvers.diff_engine.helpers import (
     _chain_add,
     normalize_shape,