feat: show user dims with sizes in PiecewiseFormulation header

Match Constraint repr style: `name` [dim: size, ...] — method

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

Author: FBumann

linopy/piecewise.py

@@ -77,7 +77,18 @@ class PiecewiseFormulation:
     constraints: Constraints
 
     def __repr__(self) -> str:
-        r = f"PiecewiseFormulation `{self.name}` — {self.method}\n"
+        # Collect user-facing dims with sizes (skip internal _ prefixed dims)
+        user_dims: dict[str, int] = {}
+        for var in self.variables.data.values():
+            for d in var.coords:
+                ds = str(d)
+                if not ds.startswith("_") and ds not in user_dims:
+                    user_dims[ds] = var.data.sizes[d]
+        dims_str = ", ".join(f"{d}: {s}" for d, s in user_dims.items())
+        header = f"PiecewiseFormulation `{self.name}`"
+        if dims_str:
+            header += f" [{dims_str}]"
+        r = f"{header} — {self.method}\n"
         r += "  Variables:\n"
         for vname, var in self.variables.items():
             dims = ", ".join(str(d) for d in var.coords) if var.coords else ""