Fix file picker nonexistent path crash

README.md

@@ -236,6 +236,8 @@ Bundle common parameter combinations into named presets so teammates can run fre
 
 `fallbackToDefault` fills in any missing parameters from the automatically generated `<default>` set.
 
+`fallbackToExisting` (optional, works with `fallbackToDefault`) prevents clearing field values when switching to this argument set if the set doesn't define a value for a parameter (or has an empty value). When set to `true`, existing values in the form are preserved instead of being cleared or overwritten with empty defaults. This is useful when you want to change only specific parameters while keeping others unchanged.
+
 ## Ready-to-run examples
 
 The repository ships with `examples/ScriptRunnerExamples.json`, a manifest that contains four minimal actions showcasing how to wrap PowerShell, Python, Bash (via WSL), and .NET console apps. Import that file from **Settings ➜ Config sources** and you will get the following definitions (interactive inputs and troubleshooting rules are omitted here for brevity):

schema/v1/ScriptRunnerSchema.json

@@ -82,6 +82,10 @@
                                     "type":"boolean",
                                     "description":"When true any missing parameter values inherit from the auto-generated default set."
                                 },
+                                "fallbackToExisting":{
+                                    "type":"boolean",
+                                    "description":"When true preserves current field values when switching to this set if the set doesn't define a value or has an empty value for a parameter. Works with fallbackToDefault."
+                                },
                                 "arguments":{
                                     "type":"object",
                                     "description":"Map of parameter name to the value that should be pre-filled when this preset is selected.",

src/ScriptRunner/ScriptRunner.GUI/Parameters/FileContent.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.IO;
 using System.Security.Cryptography;
 using System.Text;
@@ -18,7 +18,7 @@ public FileContent(string extension, bool useWslPath)
     {
         _extension = extension;
         _useWslPath = useWslPath;
-        FileName = Path.GetTempFileName() + "." + extension;
+        FileName = GetFileContentStoragePath("temp." + extension);
     }
 
     public string GetFormattedValue()
@@ -30,12 +30,21 @@ public string GetFormattedValue()
             _ => ((TextBox)Control).Text
         };
         var hash = string.IsNullOrWhiteSpace(fileContent)? "EMPTY" : ComputeSHA256(fileContent).Substring(0,10);
-        FileName = Path.Combine(Path.GetTempPath(), hash + "." + _extension);
+        FileName = GetFileContentStoragePath(hash + "." + _extension);
         File.WriteAllText(FileName, fileContent, Encoding.UTF8);
         return _useWslPath ? WslPathConverter.ConvertToWslPath(FileName) : FileName;
     }
 
 
+    private static string GetFileContentStoragePath(string fileName)
+    {
+        var appDataPath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData), "ScriptRunner", "FileContentStorage");
+        if (Directory.Exists(appDataPath) == false)
+        {
+            Directory.CreateDirectory(appDataPath);
+        }
+        return Path.Combine(appDataPath, fileName);
+    }
 
     static string ComputeSHA256(string input)
     {

src/ScriptRunner/ScriptRunner.GUI/ScriptConfigs/ScriptConfig.cs

@@ -1,4 +1,4 @@
-using Avalonia.Controls.Documents;
+using Avalonia.Controls.Documents;
 using System;
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
@@ -53,6 +53,7 @@ public class ArgumentSet
 {
     public string Description { get; set; }
     public bool FallbackToDefault { get; set; }
+    public bool FallbackToExisting { get; set; }
     public Dictionary<string, string> Arguments { get; set; } = new();
 }
 

src/ScriptRunner/ScriptRunner.GUI/ScriptReader/ScriptConfigReader.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Data.SqlTypes;
 using System.Diagnostics.CodeAnalysis;
@@ -181,6 +181,11 @@ string ResolveAbsolutePath(string path)
                     {
                         if (set.Arguments.ContainsKey(key) == false)
                         {
+                            // If fallbackToExisting is true, only set the value if the default value exists (is not null or empty)
+                            if (set.FallbackToExisting && string.IsNullOrEmpty(val))
+                            {
+                                continue;
+                            }
                             set.Arguments[key] = val;
                         }
                     }
@@ -348,6 +353,11 @@ string ResolveAbsolutePath(string path)
                     {
                         if (set.Arguments.ContainsKey(key) == false)
                         {
+                            // If fallbackToExisting is true, only set the value if the default value exists (is not null or empty)
+                            if (set.FallbackToExisting && string.IsNullOrEmpty(val))
+                            {
+                                continue;
+                            }
                             set.Arguments[key] = val;
                         }
                     }

src/ScriptRunner/ScriptRunner.GUI/Scripts/TextInputScript.json

@@ -27,6 +27,57 @@
         }
       ]
     },
+    {
+      "name": "FallbackToExisting Demo",
+      "description": "Demonstrates the fallbackToExisting feature",
+      "command": "echo Server: {server}, Port: {port}, Username: {username}",
+      "params": [
+        {
+          "name": "server",
+          "description": "Server address",
+          "prompt": "text",
+          "default": "localhost"
+        },
+        {
+          "name": "port",
+          "description": "Port number",
+          "prompt": "text",
+          "default": ""
+        },
+        {
+          "name": "username",
+          "description": "Username",
+          "prompt": "text",
+          "default": ""
+        }
+      ],
+      "predefinedArgumentSets": [
+        {
+          "description": "Production Server Only",
+          "fallbackToDefault": true,
+          "fallbackToExisting": true,
+          "arguments": {
+            "server": "prod.example.com"
+          }
+        },
+        {
+          "description": "Dev Server (clears other fields)",
+          "fallbackToDefault": true,
+          "arguments": {
+            "server": "dev.example.com"
+          }
+        },
+        {
+          "description": "Full Production Config",
+          "fallbackToDefault": true,
+          "arguments": {
+            "server": "prod.example.com",
+            "port": "443",
+            "username": "admin"
+          }
+        }
+      ]
+    },
     {
       "name": "AllControlsTest",
       "description": "Demo of all available controls",

src/ScriptRunner/ScriptRunner.GUI/ViewModels/MainWindowViewModel.cs

@@ -794,6 +794,34 @@ public ArgumentSet? SelectedArgumentSet
                     }
                 }
 
+                // Handle fallbackToExisting: preserve current values when new set has empty values
+                if (_selectedArgumentSet.FallbackToExisting && _controlRecords != null)
+                {
+                    // Harvest current parameter values from UI controls
+                    var currentValues = new Dictionary<string, string>();
+                    foreach (var controlRecord in _controlRecords)
+                    {
+                        var controlValue = controlRecord.GetFormattedValue()?.Trim();
+                        if (!string.IsNullOrEmpty(controlValue))
+                        {
+                            currentValues[controlRecord.Name] = controlValue;
+                        }
+                    }
+
+                    // Merge: use new set's values if non-empty, otherwise preserve current values
+                    arguments = new Dictionary<string, string>(arguments);
+                    foreach (var param in selectedAction.Params)
+                    {
+                        // If the new set doesn't have this parameter or has an empty value
+                        if ((!arguments.ContainsKey(param.Name) || string.IsNullOrEmpty(arguments[param.Name])) 
+                            && currentValues.ContainsKey(param.Name))
+                        {
+                            // Preserve the current value
+                            arguments[param.Name] = currentValues[param.Name];
+                        }
+                    }
+                }
+
                 RenderParameterForm(selectedAction, arguments);
             }
         }

src/ScriptRunner/ScriptRunner.GUI/Views/FilePicker.axaml.cs

@@ -39,7 +39,7 @@ private async void ChangeFileClick(object? sender, RoutedEventArgs e)
                 var sourceWindow = (sender as Control)?.GetVisualRoot() as Window ?? desktop.MainWindow;
 
                 var dialog = new OpenFileDialog();
-                if (string.IsNullOrWhiteSpace(FilePath) == false && Path.GetDirectoryName(FilePath) is { } dir)
+                if (string.IsNullOrWhiteSpace(FilePath) == false && Path.GetDirectoryName(FilePath) is { } dir && Directory.Exists(dir))
                 {
                     dialog.Directory = dir;
                     dialog.InitialFileName = Path.GetFileName(FilePath);