Fix P2S showing carbon rod maintenance tasks (#640)

P2S uses hardened steel rods, not carbon fiber. Move P2S from
  carbon rod classification to new steel_rod category with its own
  "Lubricate Steel Rods" / "Clean Steel Rods" maintenance tasks.

backend/app/api/routes/maintenance.py

@@ -34,7 +34,7 @@ router = APIRouter(prefix="/maintenance", tags=["maintenance"])
 
 # Default maintenance types
 DEFAULT_MAINTENANCE_TYPES = [
-    # Carbon rod models only (X1/P1/P2S)
+    # Carbon rod models only (X1/P1)
     {
         "name": "Lubricate Carbon Rods",
         "description": "Apply lubricant to carbon rods for smooth motion",
@@ -47,6 +47,19 @@ DEFAULT_MAINTENANCE_TYPES = [
         "default_interval_hours": 100.0,
         "icon": "Sparkles",
     },
+    # Steel rod models only (P2S)
+    {
+        "name": "Lubricate Steel Rods",
+        "description": "Apply lubricant to steel rods for smooth motion",
+        "default_interval_hours": 50.0,
+        "icon": "Droplet",
+    },
+    {
+        "name": "Clean Steel Rods",
+        "description": "Wipe steel rods with a dry cloth",
+        "default_interval_hours": 100.0,
+        "icon": "Sparkles",
+    },
     # Linear rail models only (A1/H2)
     {
         "name": "Lubricate Linear Rails",
@@ -88,11 +101,13 @@ DEFAULT_MAINTENANCE_TYPES = [
 ]
 
 # System types that only apply to printers with a specific rod/rail type.
-# "carbon" = X1/P1/P2S series (carbon rods), "linear_rail" = A1/H2 series.
-# Types not listed here apply to all printers.
+# "carbon" = X1/P1 series (carbon rods), "steel_rod" = P2S (steel rods),
+# "linear_rail" = A1/H2 series. Types not listed here apply to all printers.
 _ROD_TYPE_REQUIREMENTS: dict[str, str] = {
     "Lubricate Carbon Rods": "carbon",
     "Clean Carbon Rods": "carbon",
+    "Lubricate Steel Rods": "steel_rod",
+    "Clean Steel Rods": "steel_rod",
     "Lubricate Linear Rails": "linear_rail",
     "Clean Linear Rails": "linear_rail",
 }

backend/app/utils/printer_models.py

@@ -50,7 +50,8 @@ PRINTER_MODEL_ID_MAP = {
 
 
 # Rod/rail type classification for maintenance tasks.
-# Carbon rods: X1, P1, P2S series (CoreXY with carbon fiber rods)
+# Carbon rods: X1, P1 series (CoreXY with carbon fiber rods)
+# Steel rods: P2S series (hardened steel linear shafts)
 # Linear rails: A1, H2 series (linear rail motion system)
 # Values must be uppercase with spaces stripped for normalized comparison.
 CARBON_ROD_MODELS = frozenset(
@@ -61,11 +62,18 @@ CARBON_ROD_MODELS = frozenset(
         "X1E",
         "P1P",
         "P1S",
-        "P2S",
         # Internal codes
         "C11",  # X1C
         "C12",  # X1
         "C13",  # X1E
+    ]
+)
+
+STEEL_ROD_MODELS = frozenset(
+    [
+        # Display names (uppercase, no spaces)
+        "P2S",
+        # Internal codes
         "N7",  # P2S
     ]
 )
@@ -99,7 +107,8 @@ def get_rod_type(model: str | None) -> str | None:
     """Return the rod/rail type for a printer model.
 
     Returns:
-        "carbon" for X1/P1/P2S series (carbon fiber rods),
+        "carbon" for X1/P1 series (carbon fiber rods),
+        "steel_rod" for P2S series (hardened steel rods),
         "linear_rail" for A1/H2 series (linear rails),
         None for unknown models.
     """
@@ -108,6 +117,8 @@ def get_rod_type(model: str | None) -> str | None:
     normalized = model.strip().upper().replace(" ", "").replace("-", "")
     if normalized in CARBON_ROD_MODELS:
         return "carbon"
+    if normalized in STEEL_ROD_MODELS:
+        return "steel_rod"
     if normalized in LINEAR_RAIL_MODELS:
         return "linear_rail"
     return None

backend/tests/unit/test_maintenance_rod_filtering.py

@@ -0,0 +1,56 @@
+"""Unit tests for maintenance rod-type filtering logic."""
+
+import pytest
+
+from backend.app.api.routes.maintenance import _should_apply_to_printer
+
+
+class TestShouldApplyToPrinter:
+    """Tests for _should_apply_to_printer() model-specific filtering."""
+
+    # Carbon rod tasks should only apply to X1/P1 models
+    @pytest.mark.parametrize("model", ["X1C", "X1", "X1E", "P1P", "P1S"])
+    def test_carbon_rod_tasks_apply_to_carbon_models(self, model: str):
+        assert _should_apply_to_printer("Lubricate Carbon Rods", model) is True
+        assert _should_apply_to_printer("Clean Carbon Rods", model) is True
+
+    def test_carbon_rod_tasks_do_not_apply_to_p2s(self):
+        """P2S has steel rods, not carbon rods (#640)."""
+        assert _should_apply_to_printer("Lubricate Carbon Rods", "P2S") is False
+        assert _should_apply_to_printer("Clean Carbon Rods", "P2S") is False
+
+    def test_carbon_rod_tasks_do_not_apply_to_a1(self):
+        assert _should_apply_to_printer("Lubricate Carbon Rods", "A1") is False
+
+    # Steel rod tasks should only apply to P2S
+    def test_steel_rod_tasks_apply_to_p2s(self):
+        assert _should_apply_to_printer("Lubricate Steel Rods", "P2S") is True
+        assert _should_apply_to_printer("Clean Steel Rods", "P2S") is True
+
+    def test_steel_rod_tasks_do_not_apply_to_x1c(self):
+        assert _should_apply_to_printer("Lubricate Steel Rods", "X1C") is False
+        assert _should_apply_to_printer("Clean Steel Rods", "X1C") is False
+
+    def test_steel_rod_tasks_do_not_apply_to_a1(self):
+        assert _should_apply_to_printer("Lubricate Steel Rods", "A1") is False
+
+    # Linear rail tasks should only apply to A1/H2 models
+    @pytest.mark.parametrize("model", ["A1", "A1 Mini", "H2D", "H2C", "H2S"])
+    def test_linear_rail_tasks_apply_to_rail_models(self, model: str):
+        assert _should_apply_to_printer("Lubricate Linear Rails", model) is True
+        assert _should_apply_to_printer("Clean Linear Rails", model) is True
+
+    def test_linear_rail_tasks_do_not_apply_to_p2s(self):
+        assert _should_apply_to_printer("Lubricate Linear Rails", "P2S") is False
+
+    # Universal tasks apply to all models
+    @pytest.mark.parametrize("model", ["X1C", "P2S", "A1", "H2D"])
+    def test_universal_tasks_apply_to_all(self, model: str):
+        assert _should_apply_to_printer("Clean Nozzle/Hotend", model) is True
+        assert _should_apply_to_printer("Check Belt Tension", model) is True
+
+    # Unknown models default to carbon (legacy behavior)
+    def test_unknown_model_defaults_to_carbon(self):
+        assert _should_apply_to_printer("Lubricate Carbon Rods", "UNKNOWN") is True
+        assert _should_apply_to_printer("Lubricate Steel Rods", "UNKNOWN") is False
+        assert _should_apply_to_printer("Lubricate Linear Rails", "UNKNOWN") is False

backend/tests/unit/test_printer_models.py

@@ -0,0 +1,48 @@
+"""Unit tests for printer model utilities."""
+
+import pytest
+
+from backend.app.utils.printer_models import get_rod_type
+
+
+class TestGetRodType:
+    """Tests for get_rod_type() rod/rail classification."""
+
+    @pytest.mark.parametrize("model", ["X1C", "X1", "X1E", "P1P", "P1S"])
+    def test_carbon_rod_models(self, model: str):
+        assert get_rod_type(model) == "carbon"
+
+    @pytest.mark.parametrize("model", ["C11", "C12", "C13"])
+    def test_carbon_rod_internal_codes(self, model: str):
+        assert get_rod_type(model) == "carbon"
+
+    def test_p2s_is_steel_rod(self):
+        """P2S uses hardened steel rods, not carbon rods (#640)."""
+        assert get_rod_type("P2S") == "steel_rod"
+
+    def test_p2s_internal_code_is_steel_rod(self):
+        """N7 (P2S internal code) uses steel rods."""
+        assert get_rod_type("N7") == "steel_rod"
+
+    @pytest.mark.parametrize("model", ["A1", "A1 Mini", "H2D", "H2D Pro", "H2C", "H2S"])
+    def test_linear_rail_models(self, model: str):
+        assert get_rod_type(model) == "linear_rail"
+
+    @pytest.mark.parametrize("model", ["N1", "N2S", "A11", "A12", "O1D", "O1E", "O2D", "O1C", "O1C2", "O1S"])
+    def test_linear_rail_internal_codes(self, model: str):
+        assert get_rod_type(model) == "linear_rail"
+
+    def test_unknown_model_returns_none(self):
+        assert get_rod_type("UNKNOWN") is None
+
+    def test_none_returns_none(self):
+        assert get_rod_type(None) is None
+
+    def test_case_insensitive(self):
+        assert get_rod_type("p2s") == "steel_rod"
+        assert get_rod_type("x1c") == "carbon"
+        assert get_rod_type("a1") == "linear_rail"
+
+    def test_strips_whitespace_and_dashes(self):
+        assert get_rod_type(" P2S ") == "steel_rod"
+        assert get_rod_type("A1-Mini") == "linear_rail"