From 202a57899eab0fef0b33c334391541de73d2b4cb Mon Sep 17 00:00:00 2001
From: PP1 <74917296+pengpengyi92@users.noreply.github.com>
Date: Fri, 30 Oct 2026 09:02:59 +0800
Subject: [PATCH 1/2] fix: preserve caller baskets during legacy int-to-float
 casts

Signed-off-by: PP1 <74917296+pengpengyi92@users.noreply.github.com>
---
 csp/impl/wiring/signature.py    |  9 ++++++--
 csp/tests/test_type_checking.py | 38 +++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/csp/impl/wiring/signature.py b/csp/impl/wiring/signature.py
index 79285b011..828a39081 100644
--- a/csp/impl/wiring/signature.py
+++ b/csp/impl/wiring/signature.py
@@ -195,7 +195,10 @@ def parse_inputs(self, forced_tvars, *args, allow_none_ts=False, **kwargs):
                         if declared_type.__args__[0].typ is float:
                             from csp.baselib import cast_int_to_float
 
-                            resolved_input[j] = cast_int_to_float(resolved_input[j])
+                            # Copy once before casting a basket that may alias the caller's input.
+                            if resolved_ts_inputs[i] is resolved_input:
+                                resolved_ts_inputs[i] = resolved_input.copy()
+                            resolved_ts_inputs[i][j] = cast_int_to_float(edge)
             elif isinstance(resolved_input, dict):
                 declared_type = GenericValuesResolver.resolve_generic_values(input.typ, tvars)
                 for k, edge in resolved_input.items():
@@ -203,7 +206,9 @@ def parse_inputs(self, forced_tvars, *args, allow_none_ts=False, **kwargs):
                         if declared_type.__args__[1].typ is float:
                             from csp.baselib import cast_int_to_float
 
-                            resolved_input[k] = cast_int_to_float(resolved_input[k])
+                            if resolved_ts_inputs[i] is resolved_input:
+                                resolved_ts_inputs[i] = resolved_input.copy()
+                            resolved_ts_inputs[i][k] = cast_int_to_float(edge)
 
         return tuple(type_resolver.ts_inputs), tuple(type_resolver.scalar_inputs), type_resolver.tvars
 
diff --git a/csp/tests/test_type_checking.py b/csp/tests/test_type_checking.py
index 456ad7899..8209a06ae 100644
--- a/csp/tests/test_type_checking.py
+++ b/csp/tests/test_type_checking.py
@@ -601,6 +601,44 @@ def graph():
 
         build_graph(graph)
 
+    def test_graph_basket_cast_preserves_inputs(self):
+        @csp.graph
+        def accepts_float(x: Dict[str, ts[float]], y: List[ts[float]]) -> ts[bool]:
+            return csp.const(True)
+
+        def graph():
+            edge = csp.const(1)
+            x, y = {"a": edge}, [edge]
+            accepts_float(x, y)
+            self.assertIs(x["a"], edge)
+            self.assertIs(y[0], edge)
+            csp.cast_int_to_float(x["a"])
+            csp.cast_int_to_float(y[0])
+
+        build_graph(graph)
+
+    def test_node_basket_cast_preserves_inputs(self):
+        @csp.node
+        def accepts_float(x: Dict[str, ts[float]], y: List[ts[float]]) -> ts[float]:
+            if csp.ticked(x, y):
+                return x["a"] + x["b"] + x["c"] + y[0] + y[1] + y[2]
+
+        def graph():
+            integer, other_integer, floating = csp.const(1), csp.const(2), csp.const(2.5)
+            x, y = {"a": integer, "b": other_integer, "c": floating}, [integer, other_integer, floating]
+            result = accepts_float(x, y)
+            self.assertIs(x["a"], integer)
+            self.assertIs(x["b"], other_integer)
+            self.assertIs(x["c"], floating)
+            self.assertIs(y[0], integer)
+            self.assertIs(y[1], other_integer)
+            self.assertIs(y[2], floating)
+            return result
+
+        result = csp.run(graph, starttime=datetime(2020, 1, 1), endtime=timedelta())
+        self.assertEqual(result[0][0][1], 11.0)
+        self.assertIs(type(result[0][0][1]), float)
+
     def test_basket_type_check_bug(self):
         # Tests a bug that wasn't covered in the initial implementation. The code below was crashing on _ForwardRef before the fix
         @csp.node

From 993c949e42ff9c0ad7b53302256252c91a33e744 Mon Sep 17 00:00:00 2001
From: PP1 <74917296+pengpengyi92@users.noreply.github.com>
Date: Fri, 30 Oct 2026 09:04:52 +0800
Subject: [PATCH 2/2] test: assert converted basket entries are floats at
 runtime

Signed-off-by: PP1 <74917296+pengpengyi92@users.noreply.github.com>
---
 csp/tests/test_type_checking.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/csp/tests/test_type_checking.py b/csp/tests/test_type_checking.py
index 8209a06ae..f3d0077fd 100644
--- a/csp/tests/test_type_checking.py
+++ b/csp/tests/test_type_checking.py
@@ -621,6 +621,10 @@ def test_node_basket_cast_preserves_inputs(self):
         @csp.node
         def accepts_float(x: Dict[str, ts[float]], y: List[ts[float]]) -> ts[float]:
             if csp.ticked(x, y):
+                self.assertIs(type(x["a"]), float)
+                self.assertIs(type(x["b"]), float)
+                self.assertIs(type(y[0]), float)
+                self.assertIs(type(y[1]), float)
                 return x["a"] + x["b"] + x["c"] + y[0] + y[1] + y[2]
 
         def graph():