feat(posts): trigger the Cincinnati safety head raise by rapid length

The safety raise (M47 P<SafetyHeadraiseDistance>) used to fire only when
the next part had a different drawing name, which has nothing to do with
crash risk: a long rapid between copies of the same part got a plain M47,
while a short hop between neighbouring different drawings got the full
raise. Sheets are rarely flat (5/8" plate can be ~1.5" out of flat within
supplier tolerance), and longer rapids cross more of that bow.

Add SafetyHeadraiseRapidDistance (program units, default 12"): any rapid to
the next pierce longer than it takes the safety raise, regardless of
drawing. Unknown travel never does.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Posts/OpenNest.Posts.Cincinnati/CincinnatiFeatureWriter.cs

@@ -18,12 +18,6 @@ public sealed class FeatureContext
     public bool IsFirstFeatureOfPart { get; set; }
     public bool IsLastFeatureOnSheet { get; set; }
 
-    /// <summary>
-    /// True when the rapid after this feature goes to a different part, so its head
-    /// raise is the safety head raise.
-    /// </summary>
-    public bool IsSafetyHeadraise { get; set; }
-
     /// <summary>True when this feature cuts the part's exterior (selects ExteriorM47).</summary>
     public bool IsExteriorFeature { get; set; }
     public bool IsEtch { get; set; }
@@ -32,8 +26,8 @@ public sealed class FeatureContext
     public double SheetDiagonal { get; set; }
 
     /// <summary>
-    /// Rapid travel from this feature's end to the next pierce, used by
-    /// <see cref="M47Mode.Auto"/>. Null when unknown.
+    /// Rapid travel from this feature's end to the next pierce, used by the safety
+    /// head raise and <see cref="M47Mode.Auto"/>. Null when unknown.
     /// </summary>
     public double? RapidDistance { get; set; }
 
@@ -332,12 +326,7 @@ public sealed class CincinnatiFeatureWriter
 
     private void WriteM47(TextWriter writer, FeatureContext ctx)
     {
-        var line = CincinnatiHeadRaise.Line(
-            _config,
-            ctx.IsSafetyHeadraise,
-            ctx.IsExteriorFeature,
-            ctx.RapidDistance
-        );
+        var line = CincinnatiHeadRaise.Line(_config, ctx.IsExteriorFeature, ctx.RapidDistance);
         if (line != null)
             writer.WriteLine(line);
     }

Posts/OpenNest.Posts.Cincinnati/CincinnatiHeadRaise.cs

@@ -5,19 +5,13 @@ namespace OpenNest.Posts.Cincinnati;
 /// </summary>
 internal static class CincinnatiHeadRaise
 {
-    /// <param name="isSafetyHeadraise">True when the rapid goes to a different part.</param>
     /// <param name="isExterior">True when the feature just cut is a part exterior.</param>
     /// <param name="rapidDistance">Travel to the next pierce; null when unknown.</param>
     /// <returns>The block to write, or null for no head raise.</returns>
-    internal static string Line(
-        CincinnatiPostConfig config,
-        bool isSafetyHeadraise,
-        bool isExterior,
-        double? rapidDistance
-    )
+    internal static string Line(CincinnatiPostConfig config, bool isExterior, double? rapidDistance)
     {
-        if (isSafetyHeadraise && config.SafetyHeadraiseDistance.HasValue)
-            return $"M47 P{config.SafetyHeadraiseDistance.Value} (Safety Headraise)";
+        if (IsSafetyRapid(config, rapidDistance))
+            return SafetyLine(config);
 
         var mode = isExterior ? config.ExteriorM47 : config.InteriorM47;
         return mode switch
@@ -29,6 +23,19 @@ internal static class CincinnatiHeadRaise
         };
     }
 
+    /// <summary>
+    /// True when the rapid is long enough to cross warped plate, so it takes the
+    /// safety head raise. Unknown travel never does.
+    /// </summary>
+    internal static bool IsSafetyRapid(CincinnatiPostConfig config, double? rapidDistance) =>
+        config.SafetyHeadraiseDistance.HasValue
+        && config.SafetyHeadraiseRapidDistance is { } threshold
+        && rapidDistance is { } distance
+        && distance > threshold;
+
+    internal static string SafetyLine(CincinnatiPostConfig config) =>
+        $"M47 P{config.SafetyHeadraiseDistance.Value} (Safety Headraise)";
+
     // Unknown travel, or no threshold configured, always gets the full raise.
     private static bool IsLongRapid(CincinnatiPostConfig config, double? rapidDistance) =>
         config.M47OverrideDistanceThreshold is not { } threshold

Posts/OpenNest.Posts.Cincinnati/CincinnatiHoleCallWriter.cs

@@ -17,9 +17,9 @@ internal static class CincinnatiHoleCallWriter
     /// Unmapped calls fall back to the call's own id.
     /// </param>
     /// <param name="partName">Part-name comment to emit when the call opens a part, else null.</param>
-    /// <param name="isSafetyHeadraise">
-    /// True when the call is a part's first feature after another part, matching the
-    /// feature writer's safety head raise.
+    /// <param name="rapidDistance">
+    /// Travel from the call to the next pierce, which selects the safety head raise;
+    /// null when unknown.
     /// </param>
     internal static void Write(
         TextWriter w,
@@ -31,7 +31,7 @@ internal static class CincinnatiHoleCallWriter
         CoordinateFormatter fmt,
         IReadOnlyDictionary<Program, int> holeSubprograms,
         string partName = null,
-        bool isSafetyHeadraise = false
+        double? rapidDistance = null
     )
     {
         var postSubNum =
@@ -66,8 +66,8 @@ internal static class CincinnatiHoleCallWriter
         if (isLastFeature)
             return;
 
-        if (isSafetyHeadraise && config.SafetyHeadraiseDistance.HasValue)
-            w.WriteLine($"M47 P{config.SafetyHeadraiseDistance.Value} (Safety Headraise)");
+        if (CincinnatiHeadRaise.IsSafetyRapid(config, rapidDistance))
+            w.WriteLine(CincinnatiHeadRaise.SafetyLine(config));
         else
             w.WriteLine("M47");
     }

Posts/OpenNest.Posts.Cincinnati/CincinnatiPartSubprogramWriter.cs

@@ -89,7 +89,6 @@ public sealed class CincinnatiPartSubprogramWriter
                 PartName = drawingName,
                 IsFirstFeatureOfPart = false,
                 IsLastFeatureOnSheet = isLastFeature,
-                IsSafetyHeadraise = false,
                 IsExteriorFeature = exterior[i],
                 IsEtch = isEtch,
                 LibraryFile = isEtch ? etchLibrary : cutLibrary,

Posts/OpenNest.Posts.Cincinnati/CincinnatiPostConfig.cs

@@ -180,10 +180,17 @@ namespace OpenNest.Posts.Cincinnati
         [Category("7. Safety")]
         [DisplayName("Safety Headraise Distance")]
         [Description(
-            "Safety head raise distance in machine units, posted as M47 P<distance> before the rapid to a different part. Null = disabled."
+            "Safety head raise distance in machine units, posted as M47 P<distance> before rapids longer than the safety headraise rapid distance. Null = disabled."
         )]
         public int? SafetyHeadraiseDistance { get; set; } = 2000;
 
+        [Category("7. Safety")]
+        [DisplayName("Safety Headraise Rapid Distance")]
+        [Description(
+            "Rapids to the next pierce longer than this get the safety head raise instead of the M47 mode's raise, so the head clears warped plate. Program units. Null = disabled."
+        )]
+        public double? SafetyHeadraiseRapidDistance { get; set; } = 12.0;
+
         [Category("8. Pallet")]
         [DisplayName("Pallet Exchange")]
         [Description("When pallet exchange occurs (None, EndOfSheet, or StartAndEnd).")]

Posts/OpenNest.Posts.Cincinnati/CincinnatiSheetWriter.cs

@@ -210,9 +210,8 @@ public sealed class CincinnatiSheetWriter
             var next = i + 1 < items.Count ? items[i + 1] : null;
             var isLastFeature = next == null;
 
-            // A head raise belongs before the rapid that leaves this item, so the safety
-            // raise goes on a part's last item when a different part follows.
-            var isSafetyHeadraise = next != null && next.Part.BaseDrawing.Name != partName;
+            // A head raise belongs before the rapid that leaves this item; its travel
+            // decides whether that raise is the safety raise.
             double? rapidDistance =
                 next == null
                     ? null
@@ -228,7 +227,6 @@ public sealed class CincinnatiSheetWriter
                     item,
                     i,
                     partName,
-                    isSafetyHeadraise,
                     rapidDistance,
                     isLastFeature
                 );
@@ -250,7 +248,7 @@ public sealed class CincinnatiSheetWriter
                     _fmt,
                     _holeSubprograms,
                     isFirstFeatureOfPart ? partName : null,
-                    isSafetyHeadraise
+                    rapidDistance
                 );
                 continue;
             }
@@ -262,7 +260,6 @@ public sealed class CincinnatiSheetWriter
                 PartName = partName,
                 IsFirstFeatureOfPart = isFirstFeatureOfPart,
                 IsLastFeatureOnSheet = isLastFeature,
-                IsSafetyHeadraise = isSafetyHeadraise,
                 IsExteriorFeature = item.IsExterior,
                 IsEtch = item.IsEtch,
                 LibraryFile = item.IsEtch ? etchLibrary : cutLibrary,
@@ -296,7 +293,6 @@ public sealed class CincinnatiSheetWriter
         SheetItem item,
         int index,
         string partName,
-        bool isSafetyHeadraise,
         double? rapidDistance,
         bool isLastPart
     )
@@ -325,7 +321,7 @@ public sealed class CincinnatiSheetWriter
 
         // One head raise covers the rapid back and the rapid on. The part is complete,
         // so the raise follows the exterior M47 mode.
-        var raise = CincinnatiHeadRaise.Line(_config, isSafetyHeadraise, true, rapidDistance);
+        var raise = CincinnatiHeadRaise.Line(_config, true, rapidDistance);
         if (raise != null)
             w.WriteLine(raise);
 

Posts/OpenNest.Posts.Cincinnati/OpenNest.Posts.Cincinnati.json

@@ -20,6 +20,7 @@
   "ExteriorM47": "Always",
   "M47OverrideDistanceThreshold": null,
   "SafetyHeadraiseDistance": 2000,
+  "SafetyHeadraiseRapidDistance": 12.0,
   "PalletExchange": "EndOfSheet",
   "LeadInFeedratePercent": 0.5,
   "LeadInArcLine2FeedratePercent": 0.5,