Fix all ruff lint issues (F401, F841, E741, E402) for CI

Remove unused imports and variables in antenna_templates.py and
optimization.py, fix ambiguous variable name and mid-file imports
in test_optimization.py.

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

Author: RFingAdam

src/mcp_cst_studio/tools/antenna_templates.py

@@ -16,7 +16,7 @@
 
 from mcp_cst_studio.cst_client import CSTClient
 from mcp_cst_studio.vba_builder import VBABuilder, VBAScript
-from mcp_cst_studio.validators import validate_name, validate_frequency, validate_positive
+from mcp_cst_studio.validators import validate_frequency, validate_positive
 
 # ---------------------------------------------------------------------------
 # Physical constants
@@ -725,7 +725,7 @@ def _build_patch_antenna(args: dict) -> str:
             h, h + 0.035,
         ))
         # Feed line on top of substrate from edge to patch
-        feed_length = gnd_y / 2 - L / 2
+        gnd_y / 2 - L / 2
         script.add_raw(_build_brick(
             "Antenna", "FeedLine", "PEC",
             -feed_w / 2, feed_w / 2,
@@ -749,7 +749,7 @@ def _build_patch_antenna(args: dict) -> str:
         script.add_block(port_vba)
 
     elif feed_type == "microstrip":
-        feed_length = gnd_y / 2 - L / 2
+        gnd_y / 2 - L / 2
         script.add_raw(_build_brick(
             "Antenna", "FeedLine", "PEC",
             -feed_w / 2, feed_w / 2,
@@ -1121,10 +1121,6 @@ def _build_horn_antenna(args: dict) -> str:
 
     # Inner vacuum for horn (tapered cavity approximated via loft)
     # Use analytical VBA for loft between waveguide aperture and horn aperture
-    loft_vba_lines = [
-        "' --- Lofted horn interior (waveguide to aperture) ---",
-        "' Create rear profile (waveguide end) at z=0",
-    ]
 
     # Rear profile curve
     rear_curve = (
@@ -1260,7 +1256,7 @@ def _build_yagi_antenna(args: dict) -> str:
 
     # Create each element as a cylinder along x-axis at position z
     for name, z_pos, length in elements:
-        elem_vba = (
+        (
             VBABuilder("Cylinder")
             .call("Reset")
             .set("Name", name)
@@ -1509,7 +1505,6 @@ def _build_vivaldi_antenna(args: dict) -> str:
         R_taper = 0
 
     # Feed line (microstrip on opposite side, quarter-wave stub)
-    feed_w = 2.0  # approximate 50-ohm line width for eps_r=2.2
 
     f_min = freq * 0.5  # Vivaldi is wideband
     f_max = freq * 1.5

src/mcp_cst_studio/tools/optimization.py

@@ -570,7 +570,7 @@ def _generate_recommendations(
         f"(gap: {gap:.2f})"
     )
 
-    band_center = (f_low + f_high) / 2.0
+    (f_low + f_high) / 2.0
 
     # Resonance-based recommendations
     if nearest_resonance:
@@ -955,7 +955,7 @@ async def _optimization_loop(
 
     Only the final best-parameter application uses add_to_history.
     """
-    n = len(params_spec)
+    len(params_spec)
     param_names = [p["name"] for p in params_spec]
     x0 = [p["initial"] for p in params_spec]
     bounds = [(p["min"], p["max"]) for p in params_spec]
@@ -1259,7 +1259,7 @@ async def _handle_refine(args: dict, client: CSTClient) -> dict:
 
         # Use first band's target for the goal
         first_band = bands[0]
-        s11_threshold = vswr_to_s11(first_band.get("vswr_target", 2.5))
+        vswr_to_s11(first_band.get("vswr_target", 2.5))
         tree_path = f"1D Results\\S-Parameters\\S{port},{port}"
         vba.set("SetGoalType", "Min")
         vba.set("SetGoalResult", tree_path)

tests/test_optimization.py

@@ -2,12 +2,15 @@
 
 from __future__ import annotations
 
+import json
 import math
 import os
 import tempfile
 
 import pytest
 
+from mcp_cst_studio.cst_client import CSTClient
+
 from mcp_cst_studio.tools.optimization import (
     _analyze_impedance_band,
     _build_impedance_vba,
@@ -269,8 +272,8 @@ def test_set_params_vba(self):
     def test_set_params_vba_only_store_parameter(self):
         """VBA should only contain StoreParameter lines."""
         vba = _set_params_vba({"x": 1.0, "y": 2.0})
-        lines = [l for l in vba.split("\n") if l.strip()]
-        assert all("StoreParameter" in l for l in lines)
+        lines = [line for line in vba.split("\n") if line.strip()]
+        assert all("StoreParameter" in line for line in lines)
 
     def test_set_params_and_solve_vba(self):
         """Combined VBA stores params, solves, and exports."""
@@ -563,11 +566,6 @@ async def test_refine_validation_initial_out_of_range(self, offline_client):
         assert "initial" in data["message"]
 
 
-import json
-
-from mcp_cst_studio.cst_client import CSTClient
-
-
 # ---------------------------------------------------------------------------
 # Diagnostics tools
 # ---------------------------------------------------------------------------
@@ -669,8 +667,6 @@ class TestDialogHandler:
 
     def test_import(self):
         from mcp_cst_studio.dialog_handler import (
-            DialogWatcher,
-            dismiss_cst_dialogs,
             find_cst_dialogs,
         )
         # Functions should be importable and callable