[FIX] Inputs files: Clamp negative resource caps and coefficients to 0 before solver

optimisation/optimisation.py

@@ -723,7 +723,33 @@ def run_optimisation(
     if resource_caps is None:
         return False, {"message": "resource_caps cannot be None."}
 
-    resource_caps = dict(resource_caps)
+    # Sanitize inputs that may bypass the UI's own safeguards (widgets floor
+    # at 0, but a scenario loaded from Excel/JSON/ZIP, or a hand-edited
+    # data/inputs.csv, is never passed through those widgets). A negative
+    # resource cap is caught cleanly downstream as an infeasible LP, but a
+    # negative coefficient is not: with no other binding constraint on that
+    # resource it lets the solver report an unbounded-looking "success" with
+    # an astronomically large total instead of an error. Clamping everything
+    # to >= 0 here — the single funnel every input path (UI, Excel, ZIP,
+    # JSON, or CSV) passes through before reaching the solver — closes both.
+    resource_caps  = {r: max(0.0, float(v)) for r, v in resource_caps.items()}
+    method_costs   = {
+        m: {r: max(0.0, float(v)) for r, v in resources.items()}
+        for m, resources in method_costs.items()
+    }
+    if custom_resources:
+        custom_resources = [
+            {
+                **batch,
+                "amount": max(0.0, float(batch.get("amount", 0.0))),
+                "methods": {
+                    m: {k: max(0.0, float(v)) for k, v in coefs.items()}
+                    for m, coefs in batch.get("methods", {}).items()
+                },
+            }
+            for batch in custom_resources
+        ]
+
     method_costs  = apply_enabled_methods(method_costs, enabled_methods)
 
     # Clamp negative absolute caps to 0 to avoid infeasible LP.