Use diffs for tests

.gitignore

@@ -1,3 +1,4 @@
 *.exe
 .qodo
 *.sqlite
+testfiles

.vscode/launch.json

@@ -98,6 +98,19 @@
 			"args": [
 				"cook_tacz.yml",
 			]
+		},
+		{
+			"name": "Launch Package (ICARUS)",
+			"type": "go",
+			"request": "launch",
+			"mode": "auto",
+			"program": "${workspaceFolder}",
+			"cwd": "C:/Users/Administrator/Seafile/Games-ICARUS/Icarus/Saved/IME3/Mods",
+			"args": [
+				"-loglevel",
+				"trace",
+				"cook_processorrecipes.yml",
+			]
 		}
 	]
 }

go.mod

@@ -13,7 +13,6 @@ require (
 
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
-	github.com/google/go-cmp v0.6.0 // indirect
 	github.com/hexops/valast v1.5.0 // indirect
 	github.com/jinzhu/inflection v1.0.0 // indirect
 	github.com/jinzhu/now v1.1.5 // indirect
@@ -21,6 +20,8 @@ require (
 	github.com/mattn/go-sqlite3 v1.14.22 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/rogpeppe/go-internal v1.14.1 // indirect
+	github.com/tidwall/match v1.1.1 // indirect
+	github.com/tidwall/pretty v1.2.0 // indirect
 	golang.org/x/mod v0.21.0 // indirect
 	golang.org/x/sync v0.11.0 // indirect
 	golang.org/x/text v0.22.0 // indirect
@@ -29,4 +30,8 @@ require (
 	mvdan.cc/gofumpt v0.4.0 // indirect
 )
 
-require gorm.io/driver/sqlite v1.6.0
+require (
+	github.com/google/go-cmp v0.6.0
+	github.com/tidwall/gjson v1.18.0
+	gorm.io/driver/sqlite v1.6.0
+)

go.sum

@@ -36,6 +36,12 @@ github.com/rogpeppe/go-internal v1.14.1 h1:UQB4HGPB6osV0SQTLymcB4TgvyWu6ZyliaW0t
 github.com/rogpeppe/go-internal v1.14.1/go.mod h1:MaRKkUm5W0goXpeCfT7UZI6fk/L7L7so1lCWt35ZSgc=
 github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
 github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+github.com/tidwall/gjson v1.18.0 h1:FIDeeyB800efLX89e5a8Y0BNH+LOngJyGrIWxG2FKQY=
+github.com/tidwall/gjson v1.18.0/go.mod h1:/wbyibRr2FHMks5tjHJ5F8dMZh3AcwJEMf5vlfC0lxk=
+github.com/tidwall/match v1.1.1 h1:+Ho715JplO36QYgwN9PGYNhgZvoUSc9X2c80KVTi+GA=
+github.com/tidwall/match v1.1.1/go.mod h1:eRSPERbgtNPcGhD8UCthc6PmLEQXEWd3PRB5JTxsfmM=
+github.com/tidwall/pretty v1.2.0 h1:RWIZEg2iJ8/g6fDDYzMpobmaoGh5OLl4AXtGUGPcqCs=
+github.com/tidwall/pretty v1.2.0/go.mod h1:ITEVvHYasfjBbM0u2Pg8T2nJnzm8xPwvNhhsoaGGjNU=
 github.com/yuin/gopher-lua v1.1.1 h1:kYKnWBjvbNP4XLT3+bPEwAXJx262OhaHDWDVOPjL46M=
 github.com/yuin/gopher-lua v1.1.1/go.mod h1:GBR0iDaNXjAgGg9zfCvksxSRnQx76gclCIb7kdAd1Pw=
 golang.org/x/mod v0.21.0 h1:vvrHzRwRfVKSiLrG+d4FMl/Qi4ukBCE6kZlTUkDYRT0=

main.go

@@ -44,9 +44,13 @@ func main() {
 		fmt.Fprintf(os.Stderr, "        Reset files to their original state\n")
 		fmt.Fprintf(os.Stderr, "  -loglevel string\n")
 		fmt.Fprintf(os.Stderr, "        Set logging level: ERROR, WARNING, INFO, DEBUG, TRACE (default \"INFO\")\n")
+		fmt.Fprintf(os.Stderr, "  -json\n")
+		fmt.Fprintf(os.Stderr, "        Enable JSON mode for processing JSON files\n")
 		fmt.Fprintf(os.Stderr, "\nExamples:\n")
 		fmt.Fprintf(os.Stderr, "  Regex mode (default):\n")
 		fmt.Fprintf(os.Stderr, "    %s \"<value>(\\\\d+)</value>\" \"*1.5\" data.xml\n", os.Args[0])
+		fmt.Fprintf(os.Stderr, "  JSON mode:\n")
+		fmt.Fprintf(os.Stderr, "    %s -json data.json\n", os.Args[0])
 		fmt.Fprintf(os.Stderr, "\nNote: v1, v2, etc. are used to refer to capture groups as numbers.\n")
 		fmt.Fprintf(os.Stderr, "      s1, s2, etc. are used to refer to capture groups as strings.\n")
 		fmt.Fprintf(os.Stderr, "      Helper functions: num(str) converts string to number, str(num) converts number to string\n")
@@ -54,6 +58,8 @@ func main() {
 		fmt.Fprintf(os.Stderr, "      If expression starts with an operator like *, /, +, -, =, etc., v1 is automatically prepended\n")
 		fmt.Fprintf(os.Stderr, "      You can use any valid Lua code, including if statements, loops, etc.\n")
 		fmt.Fprintf(os.Stderr, "      Glob patterns are supported for file selection (*.xml, data/**.xml, etc.)\n")
+		fmt.Fprintf(os.Stderr, "\nLua Functions Available:\n")
+		fmt.Fprintf(os.Stderr, "%s\n", processor.GetLuaFunctionsHelp())
 	}
 	// TODO: Fix bed shitting when doing *.yml in barotrauma directory
 	flag.Parse()
@@ -426,7 +432,7 @@ func CreateExampleConfig() {
 		},
 		// Multiline regex example (DOTALL is auto-enabled). Captures numeric in nested XML.
 		{
-			Name: "XMLNestedValueMultiply",
+			Name:  "XMLNestedValueMultiply",
 			Regex: `<item>\s*\s*<name>!any<\/name>\s*\s*<value>(!num)<\/value>\s*\s*<\/item>`,
 			Lua:   `* $multiply`,
 			Files: []string{"data/**/*.xml"},
@@ -439,8 +445,8 @@ func CreateExampleConfig() {
 				`<entry>\s*\n\s*<id>(?P<id>!num)</id>\s*\n\s*<score>(?P<score>!num)</score>\s*\n\s*</entry>`,
 				`\[block\]\nkey=(?P<key>[A-Za-z_]+)\nvalue=(?P<val>!num)`,
 			},
-			Lua:   `if is_number(score) then score = score * 2 end; if is_number(val) then val = val * 3 end; return true`,
+			Lua:      `if is_number(score) then score = score * 2 end; if is_number(val) then val = val * 3 end; return true`,
-			Files: []string{"examples/**/*.*"},
+			Files:    []string{"examples/**/*.*"},
 			LogLevel: "DEBUG",
 		},
 		// Use equals operator shorthand and boolean variable
@@ -452,19 +458,19 @@ func CreateExampleConfig() {
 		},
 		// Demonstrate NoDedup to allow overlapping replacements
 		{
-			Name:   "OverlappingGroups",
+			Name:    "OverlappingGroups",
-			Regex:  `(?P<a>!num)(?P<b>!num)`,
+			Regex:   `(?P<a>!num)(?P<b>!num)`,
-			Lua:    `a = num(a) + 1; b = num(b) + 1; return true`,
+			Lua:     `a = num(a) + 1; b = num(b) + 1; return true`,
-			Files:  []string{"overlap/**/*.txt"},
+			Files:   []string{"overlap/**/*.txt"},
 			NoDedup: true,
 		},
 		// Isolate command example operating on entire matched block
 		{
-			Name:    "IsolateUppercaseBlock",
+			Name:     "IsolateUppercaseBlock",
-			Regex:   `BEGIN\n(?P<block>!any)\nEND`,
+			Regex:    `BEGIN\n(?P<block>!any)\nEND`,
-			Lua:     `block = upper(block); return true`,
+			Lua:      `block = upper(block); return true`,
-			Files:   []string{"logs/**/*.log"},
+			Files:    []string{"logs/**/*.log"},
-			Isolate: true,
+			Isolate:  true,
 			LogLevel: "TRACE",
 		},
 		// Using !rep placeholder and arrays of files
@@ -481,6 +487,25 @@ func CreateExampleConfig() {
 			Lua:   `key = $prefix .. key; return true`,
 			Files: []string{"**/*.properties"},
 		},
+		// JSON mode examples
+		{
+			Name:  "JSONArrayMultiply",
+			JSON:  true,
+			Lua:   `for i, item in ipairs(data.items) do data.items[i].value = item.value * 2 end; return true`,
+			Files: []string{"data/**/*.json"},
+		},
+		{
+			Name:  "JSONObjectUpdate",
+			JSON:  true,
+			Lua:   `data.version = "2.0.0"; data.enabled = true; return true`,
+			Files: []string{"config/**/*.json"},
+		},
+		{
+			Name:  "JSONNestedModify",
+			JSON:  true,
+			Lua:   `if data.settings and data.settings.performance then data.settings.performance.multiplier = data.settings.performance.multiplier * 1.5 end; return true`,
+			Files: []string{"settings/**/*.json"},
+		},
 	}
 
 	data, err := yaml.Marshal(commands)
@@ -506,11 +531,51 @@ func RunOtherCommands(file string, fileDataStr string, association utils.FileCom
 	runOtherCommandsLogger.Debug("Running other commands for file")
 	runOtherCommandsLogger.Trace("File data before modifications: %s", utils.LimitString(fileDataStr, 200))
 
-	// Aggregate all the modifications and execute them
+	// Separate JSON and regex commands for different processing approaches
+	jsonCommands := []utils.ModifyCommand{}
+	regexCommands := []utils.ModifyCommand{}
+
+	for _, command := range association.Commands {
+		if command.JSON || *utils.JSON {
+			jsonCommands = append(jsonCommands, command)
+		} else {
+			regexCommands = append(regexCommands, command)
+		}
+	}
+
+	// Process JSON commands sequentially (each operates on the entire file)
+	for _, command := range jsonCommands {
+		cmdLogger := logger.Default
+		if cmdLog, ok := commandLoggers[command.Name]; ok {
+			cmdLogger = cmdLog
+		}
+
+		cmdLogger.Debug("Processing file with JSON mode for command %q", command.Name)
+		newModifications, err := processor.ProcessJSON(fileDataStr, command, file)
+		if err != nil {
+			runOtherCommandsLogger.Error("Failed to process file with JSON command %q: %v", command.Name, err)
+			continue
+		}
+
+		// Apply JSON modifications immediately
+		if len(newModifications) > 0 {
+			var count int
+			fileDataStr, count = utils.ExecuteModifications(newModifications, fileDataStr)
+			atomic.AddInt64(&stats.TotalModifications, int64(count))
+			cmdLogger.Debug("Applied %d JSON modifications for command %q", count, command.Name)
+		}
+
+		count, ok := stats.ModificationsPerCommand.Load(command.Name)
+		if !ok {
+			count = 0
+		}
+		stats.ModificationsPerCommand.Store(command.Name, count.(int)+len(newModifications))
+	}
+
+	// Aggregate regex modifications and execute them
 	modifications := []utils.ReplaceCommand{}
 	numCommandsConsidered := 0
-	for _, command := range association.Commands {
+	for _, command := range regexCommands {
-		// Use command-specific logger if available, otherwise fall back to default logger
 		cmdLogger := logger.Default
 		if cmdLog, ok := commandLoggers[command.Name]; ok {
 			cmdLogger = cmdLog
@@ -572,35 +637,62 @@ func RunIsolateCommands(association utils.FileCommandAssociation, file string, f
 
 	anythingDone := false
 	for _, isolateCommand := range association.IsolateCommands {
-		runIsolateCommandsLogger.Debug("Begin processing file with isolate command %q", isolateCommand.Regex)
+		// Check if this isolate command should use JSON mode
-		patterns := isolateCommand.Regexes
+		if isolateCommand.JSON || *utils.JSON {
-		if len(patterns) == 0 {
+			runIsolateCommandsLogger.Debug("Begin processing file with JSON isolate command %q", isolateCommand.Name)
-			patterns = []string{isolateCommand.Regex}
+			modifications, err := processor.ProcessJSON(fileDataStr, isolateCommand, file)
-		}
-		for idx, pattern := range patterns {
-			tmpCmd := isolateCommand
-			tmpCmd.Regex = pattern
-			modifications, err := processor.ProcessRegex(fileDataStr, tmpCmd, file)
 			if err != nil {
-				runIsolateCommandsLogger.Error("Failed to process file with isolate command %q (pattern %d/%d): %v", isolateCommand.Name, idx+1, len(patterns), err)
+				runIsolateCommandsLogger.Error("Failed to process file with JSON isolate command %q: %v", isolateCommand.Name, err)
 				continue
 			}
 
 			if len(modifications) == 0 {
-				runIsolateCommandsLogger.Debug("Isolate command %q produced no modifications (pattern %d/%d)", isolateCommand.Name, idx+1, len(patterns))
+				runIsolateCommandsLogger.Debug("JSON isolate command %q produced no modifications", isolateCommand.Name)
 				continue
 			}
 			anythingDone = true
 
-			runIsolateCommandsLogger.Debug("Executing %d isolate modifications for file", len(modifications))
+			runIsolateCommandsLogger.Debug("Executing %d JSON isolate modifications for file", len(modifications))
-			runIsolateCommandsLogger.Trace("Isolate modifications: %v", modifications)
+			runIsolateCommandsLogger.Trace("JSON isolate modifications: %v", modifications)
 			var count int
 			fileDataStr, count = utils.ExecuteModifications(modifications, fileDataStr)
-			runIsolateCommandsLogger.Trace("File data after isolate modifications: %s", utils.LimitString(fileDataStr, 200))
+			runIsolateCommandsLogger.Trace("File data after JSON isolate modifications: %s", utils.LimitString(fileDataStr, 200))
 
 			atomic.AddInt64(&stats.TotalModifications, int64(count))
 
-			runIsolateCommandsLogger.Info("Executed %d isolate modifications for file", count)
+			runIsolateCommandsLogger.Info("Executed %d JSON isolate modifications for file", count)
+		} else {
+			// Regular regex processing for isolate commands
+			runIsolateCommandsLogger.Debug("Begin processing file with isolate command %q", isolateCommand.Regex)
+			patterns := isolateCommand.Regexes
+			if len(patterns) == 0 {
+				patterns = []string{isolateCommand.Regex}
+			}
+			for idx, pattern := range patterns {
+				tmpCmd := isolateCommand
+				tmpCmd.Regex = pattern
+				modifications, err := processor.ProcessRegex(fileDataStr, tmpCmd, file)
+				if err != nil {
+					runIsolateCommandsLogger.Error("Failed to process file with isolate command %q (pattern %d/%d): %v", isolateCommand.Name, idx+1, len(patterns), err)
+					continue
+				}
+
+				if len(modifications) == 0 {
+					runIsolateCommandsLogger.Debug("Isolate command %q produced no modifications (pattern %d/%d)", isolateCommand.Name, idx+1, len(patterns))
+					continue
+				}
+				anythingDone = true
+
+				runIsolateCommandsLogger.Debug("Executing %d isolate modifications for file", len(modifications))
+				runIsolateCommandsLogger.Trace("Isolate modifications: %v", modifications)
+				var count int
+				fileDataStr, count = utils.ExecuteModifications(modifications, fileDataStr)
+				runIsolateCommandsLogger.Trace("File data after isolate modifications: %s", utils.LimitString(fileDataStr, 200))
+
+				atomic.AddInt64(&stats.TotalModifications, int64(count))
+
+				runIsolateCommandsLogger.Info("Executed %d isolate modifications for file", count)
+			}
 		}
 	}
 	if !anythingDone {

processor/json.go

@@ -0,0 +1,656 @@
+package processor
+
+import (
+	"cook/utils"
+	"encoding/json"
+	"fmt"
+	"sort"
+	"strconv"
+	"strings"
+	"time"
+
+	logger "git.site.quack-lab.dev/dave/cylogger"
+	"github.com/tidwall/gjson"
+	lua "github.com/yuin/gopher-lua"
+)
+
+// jsonLogger is a scoped logger for the processor/json package.
+var jsonLogger = logger.Default.WithPrefix("processor/json")
+
+// ProcessJSON applies Lua processing to JSON content
+func ProcessJSON(content string, command utils.ModifyCommand, filename string) ([]utils.ReplaceCommand, error) {
+	processJsonLogger := jsonLogger.WithPrefix("ProcessJSON").WithField("commandName", command.Name).WithField("file", filename)
+	processJsonLogger.Debug("Starting JSON processing for file")
+	processJsonLogger.Trace("Initial file content length: %d", len(content))
+
+	var commands []utils.ReplaceCommand
+	startTime := time.Now()
+
+	// Parse JSON content
+	var jsonData interface{}
+	err := json.Unmarshal([]byte(content), &jsonData)
+	if err != nil {
+		processJsonLogger.Error("Failed to parse JSON content: %v", err)
+		return commands, fmt.Errorf("failed to parse JSON: %v", err)
+	}
+	processJsonLogger.Debug("Successfully parsed JSON content")
+
+	// Create Lua state
+	L, err := NewLuaState()
+	if err != nil {
+		processJsonLogger.Error("Error creating Lua state: %v", err)
+		return commands, fmt.Errorf("error creating Lua state: %v", err)
+	}
+	defer L.Close()
+
+	// Set filename global
+	L.SetGlobal("file", lua.LString(filename))
+
+	// Convert JSON data to Lua table
+	luaTable, err := ToLuaTable(L, jsonData)
+	if err != nil {
+		processJsonLogger.Error("Failed to convert JSON to Lua table: %v", err)
+		return commands, fmt.Errorf("failed to convert JSON to Lua table: %v", err)
+	}
+
+	// Set the JSON data as a global variable
+	L.SetGlobal("data", luaTable)
+	processJsonLogger.Debug("Set JSON data as Lua global 'data'")
+
+	// Build and execute Lua script for JSON mode
+	luaExpr := BuildJSONLuaScript(command.Lua)
+	processJsonLogger.Debug("Built Lua script from expression: %q", command.Lua)
+	processJsonLogger.Trace("Full Lua script: %q", utils.LimitString(luaExpr, 200))
+
+	if err := L.DoString(luaExpr); err != nil {
+		processJsonLogger.Error("Lua script execution failed: %v\nScript: %s", err, utils.LimitString(luaExpr, 200))
+		return commands, fmt.Errorf("lua script execution failed: %v", err)
+	}
+	processJsonLogger.Debug("Lua script executed successfully")
+
+	// Check if modification flag is set
+	modifiedVal := L.GetGlobal("modified")
+	if modifiedVal.Type() != lua.LTBool || !lua.LVAsBool(modifiedVal) {
+		processJsonLogger.Debug("Skipping - no modifications indicated by Lua script")
+		return commands, nil
+	}
+
+	// Get the modified data from Lua
+	modifiedData := L.GetGlobal("data")
+	if modifiedData.Type() != lua.LTTable {
+		processJsonLogger.Error("Expected 'data' to be a table after Lua processing, got %s", modifiedData.Type().String())
+		return commands, fmt.Errorf("expected 'data' to be a table after Lua processing")
+	}
+
+	// Convert back to Go interface
+	goData, err := FromLua(L, modifiedData)
+	if err != nil {
+		processJsonLogger.Error("Failed to convert Lua table back to Go: %v", err)
+		return commands, fmt.Errorf("failed to convert Lua table back to Go: %v", err)
+	}
+
+	processJsonLogger.Debug("About to call applyChanges with original data and modified data")
+	commands, err = applyChanges(content, jsonData, goData)
+	if err != nil {
+		processJsonLogger.Error("Failed to apply surgical JSON changes: %v", err)
+		return commands, fmt.Errorf("failed to apply surgical JSON changes: %v", err)
+	}
+
+	processJsonLogger.Debug("Total JSON processing time: %v", time.Since(startTime))
+	processJsonLogger.Debug("Generated %d total modifications", len(commands))
+	return commands, nil
+}
+
+// applyJSONChanges compares original and modified data and applies changes surgically
+func applyJSONChanges(content string, originalData, modifiedData interface{}) ([]utils.ReplaceCommand, error) {
+	var commands []utils.ReplaceCommand
+
+	appliedCommands, err := applyChanges(content, originalData, modifiedData)
+	if err == nil && len(appliedCommands) > 0 {
+		return appliedCommands, nil
+	}
+
+	return commands, fmt.Errorf("failed to make any changes to the json")
+}
+
+// applyChanges attempts to make surgical changes while preserving exact formatting
+func applyChanges(content string, originalData, modifiedData interface{}) ([]utils.ReplaceCommand, error) {
+	var commands []utils.ReplaceCommand
+
+	// Find all changes between original and modified data
+	changes := findDeepChanges("", originalData, modifiedData)
+
+	jsonLogger.Debug("applyChanges: Found %d changes: %v", len(changes), changes)
+
+	if len(changes) == 0 {
+		return commands, nil
+	}
+
+	// Sort removal operations by index in descending order to avoid index shifting
+	var removals []string
+	var additions []string
+	var valueChanges []string
+
+	for path := range changes {
+		if strings.HasSuffix(path, "@remove") {
+			removals = append(removals, path)
+		} else if strings.HasSuffix(path, "@add") {
+			additions = append(additions, path)
+		} else {
+			valueChanges = append(valueChanges, path)
+		}
+	}
+
+	jsonLogger.Debug("applyChanges: %d removals, %d additions, %d value changes", len(removals), len(additions), len(valueChanges))
+
+	// Apply removals first (from end to beginning to avoid index shifting)
+	for _, removalPath := range removals {
+		actualPath := strings.TrimSuffix(removalPath, "@remove")
+		elementIndex := extractIndexFromRemovalPath(actualPath)
+		arrayPath := getArrayPathFromElementPath(actualPath)
+
+		jsonLogger.Debug("Processing removal: path=%s, index=%d, arrayPath=%s", actualPath, elementIndex, arrayPath)
+
+		// Find the exact byte range to remove
+		from, to := findArrayElementRemovalRange(content, arrayPath, elementIndex)
+
+		jsonLogger.Debug("Removing bytes %d-%d", from, to)
+
+		commands = append(commands, utils.ReplaceCommand{
+			From: from,
+			To:   to,
+			With: "",
+		})
+
+		jsonLogger.Debug("Added removal command: From=%d, To=%d, With=\"\"", from, to)
+	}
+
+	// Apply additions (new fields)
+	for _, additionPath := range additions {
+		actualPath := strings.TrimSuffix(additionPath, "@add")
+		newValue := changes[additionPath]
+
+		jsonLogger.Debug("Processing addition: path=%s, value=%v", actualPath, newValue)
+
+		// Find the parent object to add the field to
+		parentPath := getParentPath(actualPath)
+		fieldName := getFieldName(actualPath)
+
+		jsonLogger.Debug("Parent path: %s, field name: %s", parentPath, fieldName)
+
+		// Get the parent object
+		var parentResult gjson.Result
+		if parentPath == "" {
+			// Adding to root object - get the entire JSON
+			parentResult = gjson.Parse(content)
+		} else {
+			parentResult = gjson.Get(content, parentPath)
+		}
+
+		if !parentResult.Exists() {
+			jsonLogger.Debug("Parent path %s does not exist, skipping", parentPath)
+			continue
+		}
+
+		// Find where to insert the new field (at the end of the object)
+		startPos := int(parentResult.Index + len(parentResult.Raw) - 1) // Before closing brace
+
+		jsonLogger.Debug("Inserting at pos %d", startPos)
+
+		// Convert the new value to JSON string
+		newValueStr := convertValueToJSONString(newValue)
+		
+		
+		// Insert the new field with pretty-printed formatting
+		// Format: ,"fieldName": { ... }
+		insertText := fmt.Sprintf(`,"%s": %s`, fieldName, newValueStr)
+		
+
+		commands = append(commands, utils.ReplaceCommand{
+			From: startPos,
+			To:   startPos,
+			With: insertText,
+		})
+
+		jsonLogger.Debug("Added addition command: From=%d, To=%d, With=%q", startPos, startPos, insertText)
+	}
+
+	// Apply value changes (in reverse order to avoid position shifting)
+	sort.Slice(valueChanges, func(i, j int) bool {
+		// Get positions for comparison
+		resultI := gjson.Get(content, valueChanges[i])
+		resultJ := gjson.Get(content, valueChanges[j])
+		return resultI.Index > resultJ.Index // Descending order
+	})
+
+	for _, path := range valueChanges {
+		newValue := changes[path]
+
+		jsonLogger.Debug("Processing value change: path=%s, value=%v", path, newValue)
+
+		// Get the current value and its position in the original JSON
+		result := gjson.Get(content, path)
+		if !result.Exists() {
+			jsonLogger.Debug("Path %s does not exist, skipping", path)
+			continue // Skip if path doesn't exist
+		}
+
+		// Get the exact byte positions of this value
+		startPos := result.Index
+		endPos := startPos + len(result.Raw)
+
+		jsonLogger.Debug("Found value at pos %d-%d: %q", startPos, endPos, result.Raw)
+
+		// Convert the new value to JSON string
+		newValueStr := convertValueToJSONString(newValue)
+
+		jsonLogger.Debug("Converting to: %q", newValueStr)
+
+		// Create a replacement command for this specific value
+		commands = append(commands, utils.ReplaceCommand{
+			From: int(startPos),
+			To:   int(endPos),
+			With: newValueStr,
+		})
+
+		jsonLogger.Debug("Added command: From=%d, To=%d, With=%q", int(startPos), int(endPos), newValueStr)
+	}
+
+	return commands, nil
+}
+
+// extractIndexFromRemovalPath extracts the array index from a removal path like "Rows.0.Inputs.1@remove"
+func extractIndexFromRemovalPath(path string) int {
+	parts := strings.Split(strings.TrimSuffix(path, "@remove"), ".")
+	if len(parts) > 0 {
+		lastPart := parts[len(parts)-1]
+		if index, err := strconv.Atoi(lastPart); err == nil {
+			return index
+		}
+	}
+	return -1
+}
+
+// getArrayPathFromElementPath converts "Rows.0.Inputs.1" to "Rows.0.Inputs"
+func getArrayPathFromElementPath(elementPath string) string {
+	parts := strings.Split(elementPath, ".")
+	if len(parts) > 0 {
+		return strings.Join(parts[:len(parts)-1], ".")
+	}
+	return ""
+}
+
+// getParentPath extracts the parent path from a full path like "Rows.0.Inputs.1"
+func getParentPath(fullPath string) string {
+	parts := strings.Split(fullPath, ".")
+	if len(parts) > 0 {
+		return strings.Join(parts[:len(parts)-1], ".")
+	}
+	return ""
+}
+
+// getFieldName extracts the field name from a full path like "Rows.0.Inputs.1"
+func getFieldName(fullPath string) string {
+	parts := strings.Split(fullPath, ".")
+	if len(parts) > 0 {
+		return parts[len(parts)-1]
+	}
+	return ""
+}
+
+// convertValueToJSONString converts a Go interface{} to a JSON string representation
+func convertValueToJSONString(value interface{}) string {
+	switch v := value.(type) {
+	case string:
+		return `"` + strings.ReplaceAll(v, `"`, `\"`) + `"`
+	case float64:
+		if v == float64(int64(v)) {
+			return strconv.FormatInt(int64(v), 10)
+		}
+		return strconv.FormatFloat(v, 'f', -1, 64)
+	case bool:
+		return strconv.FormatBool(v)
+	case nil:
+		return "null"
+	case map[string]interface{}:
+		// Handle maps specially to avoid double-escaping of keys
+		var pairs []string
+		for key, val := range v {
+			// The key might already have escaped quotes from Lua, so we need to be careful
+			// If the key already contains escaped quotes, we need to unescape them first
+			keyStr := key
+			if strings.Contains(key, `\"`) {
+				// Key already has escaped quotes, use it as-is
+				keyStr = `"` + key + `"`
+			} else {
+				// Normal key, escape quotes
+				keyStr = `"` + strings.ReplaceAll(key, `"`, `\"`) + `"`
+			}
+			valStr := convertValueToJSONString(val)
+			pairs = append(pairs, keyStr+":"+valStr)
+		}
+		return "{" + strings.Join(pairs, ",") + "}"
+	default:
+		// For other complex types (arrays), we need to use json.Marshal
+		jsonBytes, err := json.Marshal(v)
+		if err != nil {
+			return "null" // Fallback to null if marshaling fails
+		}
+		return string(jsonBytes)
+	}
+}
+
+// findArrayElementRemovalRange finds the exact byte range to remove for an array element
+func findArrayElementRemovalRange(content, arrayPath string, elementIndex int) (int, int) {
+	// Get the array using gjson
+	arrayResult := gjson.Get(content, arrayPath)
+	if !arrayResult.Exists() || !arrayResult.IsArray() {
+		return -1, -1
+	}
+
+	// Get all array elements
+	elements := arrayResult.Array()
+	if elementIndex >= len(elements) {
+		return -1, -1
+	}
+
+	// Get the target element
+	elementResult := elements[elementIndex]
+	startPos := int(elementResult.Index)
+	endPos := int(elementResult.Index + len(elementResult.Raw))
+
+	// Handle comma removal properly
+	if elementIndex == 0 && len(elements) > 1 {
+		// First element but not the only one - remove comma after
+		for i := endPos; i < len(content) && i < endPos+50; i++ {
+			if content[i] == ',' {
+				endPos = i + 1
+				break
+			}
+		}
+	} else if elementIndex == len(elements)-1 && len(elements) > 1 {
+		// Last element and not the only one - remove comma before
+		prevElementEnd := int(elements[elementIndex-1].Index + len(elements[elementIndex-1].Raw))
+		for i := prevElementEnd; i < startPos && i < len(content); i++ {
+			if content[i] == ',' {
+				startPos = i
+				break
+			}
+		}
+	}
+	// If it's the only element, don't remove any commas
+
+	return startPos, endPos
+}
+
+// findDeepChanges recursively finds all paths that need to be changed
+func findDeepChanges(basePath string, original, modified interface{}) map[string]interface{} {
+	changes := make(map[string]interface{})
+
+	switch orig := original.(type) {
+	case map[string]interface{}:
+		if mod, ok := modified.(map[string]interface{}); ok {
+			// Check for new keys added in modified data
+			for key, modValue := range mod {
+				var currentPath string
+				if basePath == "" {
+					currentPath = key
+				} else {
+					currentPath = basePath + "." + key
+				}
+
+				if origValue, exists := orig[key]; exists {
+					// Key exists in both, check if value changed
+					switch modValue.(type) {
+					case map[string]interface{}, []interface{}:
+						// Recursively check nested structures
+						nestedChanges := findDeepChanges(currentPath, origValue, modValue)
+						for nestedPath, nestedValue := range nestedChanges {
+							changes[nestedPath] = nestedValue
+						}
+					default:
+						// Primitive value - check if changed
+						if !deepEqual(origValue, modValue) {
+							changes[currentPath] = modValue
+						}
+					}
+				} else {
+					// New key added - mark for addition
+					changes[currentPath+"@add"] = modValue
+				}
+			}
+		}
+	case []interface{}:
+		if mod, ok := modified.([]interface{}); ok {
+			// Handle array changes by detecting specific element operations
+			if len(orig) != len(mod) {
+				// Array length changed - detect if it's element removal
+				if len(orig) > len(mod) {
+					// Element(s) removed - find which ones by comparing content
+					removedIndices := findRemovedArrayElements(orig, mod)
+					for _, removedIndex := range removedIndices {
+						var currentPath string
+						if basePath == "" {
+							currentPath = fmt.Sprintf("%d@remove", removedIndex)
+						} else {
+							currentPath = fmt.Sprintf("%s.%d@remove", basePath, removedIndex)
+						}
+						changes[currentPath] = nil // Mark for removal
+					}
+				} else {
+					// Elements added - more complex, skip for now
+				}
+			} else {
+				// Same length - check individual elements for value changes
+				for i, modValue := range mod {
+					var currentPath string
+					if basePath == "" {
+						currentPath = strconv.Itoa(i)
+					} else {
+						currentPath = basePath + "." + strconv.Itoa(i)
+					}
+
+					if i < len(orig) {
+						// Index exists in both, check if value changed
+						switch modValue.(type) {
+						case map[string]interface{}, []interface{}:
+							// Recursively check nested structures
+							nestedChanges := findDeepChanges(currentPath, orig[i], modValue)
+							for nestedPath, nestedValue := range nestedChanges {
+								changes[nestedPath] = nestedValue
+							}
+						default:
+							// Primitive value - check if changed
+							if !deepEqual(orig[i], modValue) {
+								changes[currentPath] = modValue
+							}
+						}
+					}
+				}
+			}
+		}
+	default:
+		// For primitive types, compare directly
+		if !deepEqual(original, modified) {
+			if basePath == "" {
+				changes[""] = modified
+			} else {
+				changes[basePath] = modified
+			}
+		}
+	}
+
+	return changes
+}
+
+// findRemovedArrayElements compares two arrays and returns indices of removed elements
+func findRemovedArrayElements(original, modified []interface{}) []int {
+	var removedIndices []int
+
+	// Simple approach: find elements in original that don't exist in modified
+	for i, origElement := range original {
+		found := false
+		for _, modElement := range modified {
+			if deepEqual(origElement, modElement) {
+				found = true
+				break
+			}
+		}
+		if !found {
+			removedIndices = append(removedIndices, i)
+		}
+	}
+
+	return removedIndices
+}
+
+// deepEqual performs deep comparison of two values
+func deepEqual(a, b interface{}) bool {
+	if a == nil && b == nil {
+		return true
+	}
+	if a == nil || b == nil {
+		return false
+	}
+
+	switch av := a.(type) {
+	case map[string]interface{}:
+		if bv, ok := b.(map[string]interface{}); ok {
+			if len(av) != len(bv) {
+				return false
+			}
+			for k, v := range av {
+				if !deepEqual(v, bv[k]) {
+					return false
+				}
+			}
+			return true
+		}
+		return false
+	case []interface{}:
+		if bv, ok := b.([]interface{}); ok {
+			if len(av) != len(bv) {
+				return false
+			}
+			for i, v := range av {
+				if !deepEqual(v, bv[i]) {
+					return false
+				}
+			}
+			return true
+		}
+		return false
+	default:
+		return a == b
+	}
+}
+
+// ToLuaTable converts a Go interface{} to a Lua table recursively
+func ToLuaTable(L *lua.LState, data interface{}) (*lua.LTable, error) {
+	toLuaTableLogger := jsonLogger.WithPrefix("ToLuaTable")
+	toLuaTableLogger.Debug("Converting Go interface to Lua table")
+	toLuaTableLogger.Trace("Input data type: %T", data)
+
+	switch v := data.(type) {
+	case map[string]interface{}:
+		toLuaTableLogger.Debug("Converting map to Lua table")
+		table := L.CreateTable(0, len(v))
+		for key, value := range v {
+			luaValue, err := ToLuaValue(L, value)
+			if err != nil {
+				toLuaTableLogger.Error("Failed to convert map value for key %q: %v", key, err)
+				return nil, err
+			}
+			table.RawSetString(key, luaValue)
+		}
+		return table, nil
+
+	case []interface{}:
+		toLuaTableLogger.Debug("Converting slice to Lua table")
+		table := L.CreateTable(len(v), 0)
+		for i, value := range v {
+			luaValue, err := ToLuaValue(L, value)
+			if err != nil {
+				toLuaTableLogger.Error("Failed to convert slice value at index %d: %v", i, err)
+				return nil, err
+			}
+			table.RawSetInt(i+1, luaValue) // Lua arrays are 1-indexed
+		}
+		return table, nil
+
+	case string:
+		toLuaTableLogger.Debug("Converting string to Lua string")
+		return nil, fmt.Errorf("expected table or array, got string")
+
+	case float64:
+		toLuaTableLogger.Debug("Converting float64 to Lua number")
+		return nil, fmt.Errorf("expected table or array, got number")
+
+	case bool:
+		toLuaTableLogger.Debug("Converting bool to Lua boolean")
+		return nil, fmt.Errorf("expected table or array, got boolean")
+
+	case nil:
+		toLuaTableLogger.Debug("Converting nil to Lua nil")
+		return nil, fmt.Errorf("expected table or array, got nil")
+
+	default:
+		toLuaTableLogger.Error("Unsupported type for Lua table conversion: %T", v)
+		return nil, fmt.Errorf("unsupported type for Lua table conversion: %T", v)
+	}
+}
+
+// ToLuaValue converts a Go interface{} to a Lua value
+func ToLuaValue(L *lua.LState, data interface{}) (lua.LValue, error) {
+	toLuaValueLogger := jsonLogger.WithPrefix("ToLuaValue")
+	toLuaValueLogger.Debug("Converting Go interface to Lua value")
+	toLuaValueLogger.Trace("Input data type: %T", data)
+
+	switch v := data.(type) {
+	case map[string]interface{}:
+		toLuaValueLogger.Debug("Converting map to Lua table")
+		table := L.CreateTable(0, len(v))
+		for key, value := range v {
+			luaValue, err := ToLuaValue(L, value)
+			if err != nil {
+				toLuaValueLogger.Error("Failed to convert map value for key %q: %v", key, err)
+				return lua.LNil, err
+			}
+			table.RawSetString(key, luaValue)
+		}
+		return table, nil
+
+	case []interface{}:
+		toLuaValueLogger.Debug("Converting slice to Lua table")
+		table := L.CreateTable(len(v), 0)
+		for i, value := range v {
+			luaValue, err := ToLuaValue(L, value)
+			if err != nil {
+				toLuaValueLogger.Error("Failed to convert slice value at index %d: %v", i, err)
+				return lua.LNil, err
+			}
+			table.RawSetInt(i+1, luaValue) // Lua arrays are 1-indexed
+		}
+		return table, nil
+
+	case string:
+		toLuaValueLogger.Debug("Converting string to Lua string")
+		return lua.LString(v), nil
+
+	case float64:
+		toLuaValueLogger.Debug("Converting float64 to Lua number")
+		return lua.LNumber(v), nil
+
+	case bool:
+		toLuaValueLogger.Debug("Converting bool to Lua boolean")
+		return lua.LBool(v), nil
+
+	case nil:
+		toLuaValueLogger.Debug("Converting nil to Lua nil")
+		return lua.LNil, nil
+
+	default:
+		toLuaValueLogger.Error("Unsupported type for Lua value conversion: %T", v)
+		return lua.LNil, fmt.Errorf("unsupported type for Lua value conversion: %T", v)
+	}
+}

processor/json_test.go

@@ -0,0 +1,96 @@
+package processor
+
+import (
+	"cook/utils"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestProcessJSON(t *testing.T) {
+	tests := []struct {
+		name           string
+		input          string
+		luaExpression  string
+		expectedOutput string
+		expectedMods   int
+	}{
+		{
+			name:           "Basic JSON object modification",
+			input:          `{"name": "test", "value": 42}`,
+			luaExpression:  `data.value = data.value * 2; return true`,
+			expectedOutput: `{"name": "test", "value": 84}`,
+			expectedMods:   1,
+		},
+		{
+			name:           "JSON array modification",
+			input:          `{"items": [{"name": "item1", "value": 10}, {"name": "item2", "value": 20}]}`,
+			luaExpression:  `for i, item in ipairs(data.items) do item.value = item.value * 2 end modified = true`,
+			expectedOutput: `{"items": [{"name": "item1", "value": 20}, {"name": "item2", "value": 40}]}`,
+			expectedMods:   2, 
+		},
+		{
+			name:           "JSON nested object modification",
+			input:          `{"config": {"setting1": {"enabled": true, "value": 5}, "setting2": {"enabled": false, "value": 10}}}`,
+			luaExpression:  `data.config.setting1.enabled = false data.config.setting2.value = 15 modified = true`,
+			expectedOutput: `{"config": {"setting1": {"enabled": false, "value": 5}, "setting2": {"enabled": false, "value": 15}}}`,
+			expectedMods:   2,
+		},
+		{
+			name:           "JSON no modification",
+			input:          `{"name": "test", "value": 42}`,
+			luaExpression:  `return false`,
+			expectedOutput: `{"name": "test", "value": 42}`,
+			expectedMods:   0,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			command := utils.ModifyCommand{
+				Name: tt.name,
+				JSON: true,
+				Lua:  tt.luaExpression,
+			}
+
+			modifications, err := ProcessJSON(tt.input, command, "test.json")
+			assert.NoError(t, err, "ProcessJSON failed: %v", err)
+
+			if len(modifications) > 0 {
+				// Execute modifications
+				result, count := utils.ExecuteModifications(modifications, tt.input)
+				assert.Equal(t, tt.expectedMods, count, "Expected %d modifications, got %d", tt.expectedMods, count)
+				assert.Equal(t, tt.expectedOutput, result, "Expected output: %s, got: %s", tt.expectedOutput, result)
+			} else {
+				assert.Equal(t, 0, tt.expectedMods, "Expected no modifications but got some")
+			}
+		})
+	}
+}
+
+func TestToLuaValue(t *testing.T) {
+	L, err := NewLuaState()
+	if err != nil {
+		t.Fatalf("Failed to create Lua state: %v", err)
+	}
+	defer L.Close()
+
+	tests := []struct {
+		name     string
+		input    interface{}
+		expected string
+	}{
+		{"string", "hello", "hello"},
+		{"number", 42.0, "42"},
+		{"boolean", true, "true"},
+		{"nil", nil, "nil"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result, err := ToLuaValue(L, tt.input)
+			assert.NoError(t, err)
+			assert.Equal(t, tt.expected, result.String())
+		})
+	}
+}

processor/processor.go

@@ -247,6 +247,7 @@ modified = false
 	initLuaHelpersLogger.Debug("Setting up Lua print function to Go")
 	L.SetGlobal("print", L.NewFunction(printToGo))
 	L.SetGlobal("fetch", L.NewFunction(fetch))
+	L.SetGlobal("re", L.NewFunction(EvalRegex))
 	initLuaHelpersLogger.Debug("Lua print and fetch functions bound to Go")
 	return nil
 }
@@ -300,6 +301,26 @@ func BuildLuaScript(luaExpr string) string {
 	return fullScript
 }
 
+// BuildJSONLuaScript prepares a Lua expression for JSON mode
+func BuildJSONLuaScript(luaExpr string) string {
+	buildJsonLuaScriptLogger := processorLogger.WithPrefix("BuildJSONLuaScript").WithField("inputLuaExpr", luaExpr)
+	buildJsonLuaScriptLogger.Debug("Building full Lua script for JSON mode from expression")
+
+	// Perform $var substitutions from globalVariables
+	luaExpr = replaceVariables(luaExpr)
+
+	fullScript := fmt.Sprintf(`
+		function run()
+			%s
+		end
+		local res = run()
+		modified = res == nil or res
+	`, luaExpr)
+	buildJsonLuaScriptLogger.Trace("Generated full JSON Lua script: %q", utils.LimitString(fullScript, 200))
+
+	return fullScript
+}
+
 func replaceVariables(expr string) string {
 	// $varName -> literal value
 	varNameRe := regexp.MustCompile(`\$(\w+)`)
@@ -461,3 +482,86 @@ func fetch(L *lua.LState) int {
 	fetchLogger.Debug("Pushed response table to Lua stack")
 	return 1
 }
+
+func EvalRegex(L *lua.LState) int {
+	evalRegexLogger := processorLogger.WithPrefix("evalRegex")
+	evalRegexLogger.Debug("Lua evalRegex function called")
+
+	defer func() {
+		if r := recover(); r != nil {
+			evalRegexLogger.Error("Panic in EvalRegex: %v", r)
+			// Push empty table on panic
+			emptyTable := L.NewTable()
+			L.Push(emptyTable)
+		}
+	}()
+
+	pattern := L.ToString(1)
+	input := L.ToString(2)
+
+	evalRegexLogger.Debug("Pattern: %q, Input: %q", pattern, input)
+
+	re := regexp.MustCompile(pattern)
+	matches := re.FindStringSubmatch(input)
+
+	evalRegexLogger.Debug("Go regex matches: %v (count: %d)", matches, len(matches))
+
+	matchesTable := L.NewTable()
+	for i, match := range matches {
+		matchesTable.RawSetInt(i, lua.LString(match))
+		evalRegexLogger.Debug("Set table[%d] = %q", i, match)
+	}
+
+	L.Push(matchesTable)
+	evalRegexLogger.Debug("Pushed matches table to Lua stack")
+
+	return 1
+}
+
+// GetLuaFunctionsHelp returns a comprehensive help string for all available Lua functions
+func GetLuaFunctionsHelp() string {
+	return `Lua Functions Available in Global Environment:
+
+MATH FUNCTIONS:
+  min(a, b)           - Returns the minimum of two numbers
+  max(a, b)           - Returns the maximum of two numbers
+  round(x, n)         - Rounds x to n decimal places (default 0)
+  floor(x)            - Returns the floor of x
+  ceil(x)             - Returns the ceiling of x
+
+STRING FUNCTIONS:
+  upper(s)            - Converts string to uppercase
+  lower(s)            - Converts string to lowercase
+  format(s, ...)      - Formats string using Lua string.format
+  trim(s)             - Removes leading/trailing whitespace
+  strsplit(inputstr, sep) - Splits string by separator (default: whitespace)
+  num(str)            - Converts string to number (returns 0 if invalid)
+  str(num)            - Converts number to string
+  is_number(str)      - Returns true if string is numeric
+
+TABLE FUNCTIONS:
+  DumpTable(table, depth) - Prints table structure recursively
+  isArray(t)          - Returns true if table is a sequential array
+
+HTTP FUNCTIONS:
+  fetch(url, options) - Makes HTTP request, returns response table
+    options: {method="GET", headers={}, body=""}
+    returns: {status, statusText, ok, body, headers}
+
+REGEX FUNCTIONS:
+  re(pattern, input)  - Applies regex pattern to input string
+    returns: table with matches (index 0 = full match, 1+ = groups)
+
+UTILITY FUNCTIONS:
+  print(...)          - Prints arguments to Go logger
+
+EXAMPLES:
+  round(3.14159, 2)   -> 3.14
+  strsplit("a,b,c", ",") -> {"a", "b", "c"}
+  upper("hello")      -> "HELLO"
+  min(5, 3)           -> 3
+  num("123")          -> 123
+  is_number("abc")    -> false
+  fetch("https://api.example.com/data")
+  re("(\\w+)@(\\w+)", "user@domain.com") -> {"user@domain.com", "user", "domain.com"}`
+}

processor/processor_test.go

@@ -0,0 +1,162 @@
+package processor_test
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	lua "github.com/yuin/gopher-lua"
+
+	"cook/processor"
+)
+
+// Happy Path: Function correctly returns all regex capture groups as Lua table when given valid pattern and input.
+func TestEvalRegex_CaptureGroupsReturned(t *testing.T) {
+	L := lua.NewState()
+	defer L.Close()
+	pattern := `(\w+)-(\d+)`
+	input := "test-42"
+	L.Push(lua.LString(pattern))
+	L.Push(lua.LString(input))
+
+	result := processor.EvalRegex(L)
+
+	assert.Equal(t, 0, result, "Expected return value to be 0")
+
+	out := L.Get(-1)
+	tbl, ok := out.(*lua.LTable)
+	if !ok {
+		t.Fatalf("Expected Lua table, got %T", out)
+	}
+	expected := []string{"test-42", "test", "42"}
+	for i, v := range expected {
+		val := tbl.RawGetString(fmt.Sprintf("%d", i))
+		assert.Equal(t, lua.LString(v), val, "Expected index %d to be %q", i, v)
+	}
+}
+
+// Happy Path: Function returns an empty Lua table when regex pattern does not match input string.
+func TestEvalRegex_NoMatchReturnsEmptyTable(t *testing.T) {
+	L := lua.NewState()
+	defer L.Close()
+	L.Push(lua.LString(`(foo)(bar)`))
+	L.Push(lua.LString("no-match-here"))
+
+	result := processor.EvalRegex(L)
+	assert.Equal(t, 0, result)
+
+	out := L.Get(-1)
+	tbl, ok := out.(*lua.LTable)
+	if !ok {
+		t.Fatalf("Expected Lua table, got %T", out)
+	}
+	count := 0
+	tbl.ForEach(func(k, v lua.LValue) {
+		count++
+	})
+	assert.Zero(t, count, "Expected no items in the table for non-matching input")
+}
+
+// Happy Path: Function handles patterns with no capture groups by returning the full match in the Lua table.
+func TestEvalRegex_NoCaptureGroups(t *testing.T) {
+	L := lua.NewState()
+	defer L.Close()
+	pattern := `foo\d+`
+	input := "foo123"
+	L.Push(lua.LString(pattern))
+	L.Push(lua.LString(input))
+
+	result := processor.EvalRegex(L)
+	assert.Equal(t, 0, result)
+
+	out := L.Get(-1)
+	tbl, ok := out.(*lua.LTable)
+	if !ok {
+		t.Fatalf("Expected Lua table, got %T", out)
+	}
+	fullMatch := tbl.RawGetString("0")
+	assert.Equal(t, lua.LString("foo123"), fullMatch)
+	// There should be only the full match (index 0)
+	count := 0
+	tbl.ForEach(func(k, v lua.LValue) {
+		count++
+	})
+	assert.Equal(t, 1, count)
+}
+
+// Edge Case: Function panics or errors when given an invalid regex pattern.
+func TestEvalRegex_InvalidPattern(t *testing.T) {
+	L := lua.NewState()
+	defer L.Close()
+	pattern := `([a-z` // invalid regex
+	L.Push(lua.LString(pattern))
+	L.Push(lua.LString("someinput"))
+
+	defer func() {
+		if r := recover(); r == nil {
+			t.Error("Expected panic for invalid regex pattern, but did not panic")
+		}
+	}()
+	processor.EvalRegex(L)
+}
+
+// Edge Case: Function returns an empty Lua table when input string is empty.
+func TestEvalRegex_EmptyInputString(t *testing.T) {
+	L := lua.NewState()
+	defer L.Close()
+	L.Push(lua.LString(`(foo)`))
+	L.Push(lua.LString(""))
+
+	result := processor.EvalRegex(L)
+	assert.Equal(t, 0, result)
+
+	out := L.Get(-1)
+	tbl, ok := out.(*lua.LTable)
+	if !ok {
+		t.Fatalf("Expected Lua table, got %T", out)
+	}
+	// Should be empty
+	count := 0
+	tbl.ForEach(func(k, v lua.LValue) {
+		count++
+	})
+	assert.Zero(t, count, "Expected empty table when input is empty")
+}
+
+// Edge Case: Function handles nil or missing arguments gracefully without causing a runtime panic.
+func TestEvalRegex_MissingArguments(t *testing.T) {
+	L := lua.NewState()
+	defer L.Close()
+	defer func() {
+		if r := recover(); r != nil {
+			t.Errorf("Did not expect panic when arguments are missing, got: %v", r)
+		}
+	}()
+	// No arguments pushed at all
+	processor.EvalRegex(L)
+	// Should just not match anything or produce empty table, but must not panic
+}
+
+func TestEvalComplexRegex(t *testing.T) {
+	// 23:47:35.567068 processor.go:369          [g:22  ] [LUA]     Pistol_Round ^((Bulk_)?(Pistol|Rifle).*?Round.*?)$
+	L := lua.NewState()
+	defer L.Close()
+	pattern := `^((Bulk_)?(Pistol|Rifle).*?Round.*?)$`
+	input := "Pistol_Round"
+	L.Push(lua.LString(pattern))
+	L.Push(lua.LString(input))
+
+	processor.EvalRegex(L)
+
+	out := L.Get(-1)
+	tbl, ok := out.(*lua.LTable)
+	if !ok {
+		t.Fatalf("Expected Lua table, got %T", out)
+	}
+	count := 0
+	tbl.ForEach(func(k, v lua.LValue) {
+		fmt.Println(k, v)
+		count++
+	})
+	assert.Equal(t, 1, count)
+}

processor/surgical_json_test.go

@@ -0,0 +1,847 @@
+package processor
+
+import (
+	"cook/utils"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+)
+
+func TestSurgicalJSONEditing(t *testing.T) {
+	tests := []struct {
+		name     string
+		content  string
+		luaCode  string
+		expected string
+	}{
+		{
+			name: "Modify single field",
+			content: `{
+  "name": "test",
+  "value": 42,
+  "description": "original"
+}`,
+			luaCode: `
+data.value = 84
+modified = true
+`,
+			expected: `{
+  "name": "test",
+  "value": 84,
+  "description": "original"
+}`,
+		},
+		{
+			name: "Add new field",
+			content: `{
+  "name": "test",
+  "value": 42
+}`,
+			luaCode: `
+data.newField = "added"
+modified = true
+`,
+			expected: `{
+  "name": "test",
+  "value": 42
+,"newField": "added"}`, // sjson.Set() adds new fields in compact format
+		},
+		{
+			name: "Modify nested field",
+			content: `{
+  "config": {
+    "settings": {
+      "enabled": false,
+      "timeout": 30
+    }
+  }
+}`,
+			luaCode: `
+data.config.settings.enabled = true
+data.config.settings.timeout = 60
+modified = true
+`,
+			expected: `{
+  "config": {
+    "settings": {
+      "enabled": true,
+      "timeout": 60
+    }
+  }
+}`,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			command := utils.ModifyCommand{
+				Name: "test",
+				Lua:  tt.luaCode,
+			}
+
+			commands, err := ProcessJSON(tt.content, command, "test.json")
+			if err != nil {
+				t.Fatalf("ProcessJSON failed: %v", err)
+			}
+
+			if len(commands) == 0 {
+				t.Fatal("Expected at least one command")
+			}
+
+			// Apply the commands
+			result := tt.content
+			for _, cmd := range commands {
+				result = result[:cmd.From] + cmd.With + result[cmd.To:]
+			}
+
+			diff := cmp.Diff(result, tt.expected)
+			if diff != "" {
+				t.Errorf("Differences:\n%s", diff)
+			}
+
+			// Check the actual result matches expected
+			if result != tt.expected {
+				t.Errorf("Expected:\n%s\n\nGot:\n%s", tt.expected, result)
+			}
+		})
+	}
+}
+
+func TestSurgicalJSONPreservesFormatting(t *testing.T) {
+	// Test that surgical editing preserves the original formatting structure
+	content := `{
+  "Defaults": {
+    "Behaviour": "None",
+    "Description": "",
+    "DisplayName": "",
+    "FlavorText": "",
+    "Icon": "None",
+    "MaxStack": 1,
+    "Override_Glow_Icon": "None",
+    "Weight": 0,
+    "bAllowZeroWeight": false
+  },
+  "RowStruct": "/Script/Icarus.ItemableData",
+  "Rows": [
+    {
+      "Description": "NSLOCTEXT(\"D_Itemable\", \"Item_Fiber-Description\", \"A bundle of soft fiber, highly useful.\")",
+      "DisplayName": "NSLOCTEXT(\"D_Itemable\", \"Item_Fiber-DisplayName\", \"Fiber\")",
+      "FlavorText": "NSLOCTEXT(\"D_Itemable\", \"Item_Fiber-FlavorText\", \"Fiber is collected from bast, the strong inner bark of certain flowering plants.\")",
+      "Icon": "/Game/Assets/2DArt/UI/Items/Item_Icons/Resources/ITEM_Fibre.ITEM_Fibre",
+      "MaxStack": 1000000,
+      "Name": "Item_Fiber",
+      "Weight": 10
+    }
+  ]
+}`
+
+	expected := `{
+  "Defaults": {
+    "Behaviour": "None",
+    "Description": "",
+    "DisplayName": "",
+    "FlavorText": "",
+    "Icon": "None",
+    "MaxStack": 1,
+    "Override_Glow_Icon": "None",
+    "Weight": 0,
+    "bAllowZeroWeight": false
+  },
+  "RowStruct": "/Script/Icarus.ItemableData",
+  "Rows": [
+    {
+      "Description": "NSLOCTEXT(\"D_Itemable\", \"Item_Fiber-Description\", \"A bundle of soft fiber, highly useful.\")",
+      "DisplayName": "NSLOCTEXT(\"D_Itemable\", \"Item_Fiber-DisplayName\", \"Fiber\")",
+      "FlavorText": "NSLOCTEXT(\"D_Itemable\", \"Item_Fiber-FlavorText\", \"Fiber is collected from bast, the strong inner bark of certain flowering plants.\")",
+      "Icon": "/Game/Assets/2DArt/UI/Items/Item_Icons/Resources/ITEM_Fibre.ITEM_Fibre",
+      "MaxStack": 1000000,
+      "Name": "Item_Fiber",
+      "Weight": 500
+    }
+  ]
+}`
+
+	command := utils.ModifyCommand{
+		Name: "test",
+		Lua: `
+-- Modify the weight of the first item
+data.Rows[1].Weight = 500
+modified = true
+`,
+	}
+
+	commands, err := ProcessJSON(content, command, "test.json")
+	if err != nil {
+		t.Fatalf("ProcessJSON failed: %v", err)
+	}
+
+	if len(commands) == 0 {
+		t.Fatal("Expected at least one command")
+	}
+
+	// Apply the commands
+	result := content
+	for _, cmd := range commands {
+		result = result[:cmd.From] + cmd.With + result[cmd.To:]
+	}
+
+	diff := cmp.Diff(result, expected)
+	if diff != "" {
+		t.Errorf("Differences:\n%s", diff)
+	}
+
+	// Check that the result matches expected (preserves formatting and changes weight)
+	if result != expected {
+		t.Errorf("Expected:\n%s\n\nGot:\n%s", expected, result)
+	}
+}
+
+func TestSurgicalJSONPreservesFormatting2(t *testing.T) {
+	// Test that surgical editing preserves the original formatting structure
+	content := `
+{
+  "RowStruct": "/Script/Icarus.ProcessorRecipe",
+  "Defaults": {
+    "bForceDisableRecipe": false,
+    "Requirement": {
+      "RowName": "None",
+      "DataTableName": "D_Talents"
+    },
+    "SessionRequirement": {
+      "RowName": "None",
+      "DataTableName": "D_CharacterFlags"
+    },
+    "CharacterRequirement": {
+      "RowName": "None",
+      "DataTableName": "D_CharacterFlags"
+    },
+    "RequiredMillijoules": 2500,
+    "RecipeSets": [],
+    "ResourceCostMultipliers": [],
+    "Inputs": [
+      {
+        "Element": {
+          "RowName": "None",
+          "DataTableName": "D_ItemsStatic"
+        },
+        "Count": 1,
+        "DynamicProperties": []
+      }
+    ],
+    "Container": {
+      "Value": "None"
+    },
+    "ResourceInputs": [],
+    "bSelectOutputItemRandomly": false,
+    "bContainsContainer": false,
+    "ItemIconOverride": {
+      "ItemStaticData": {
+        "RowName": "None",
+        "DataTableName": "D_ItemsStatic"
+      },
+      "ItemDynamicData": [],
+      "ItemCustomStats": [],
+      "CustomProperties": {
+        "StaticWorldStats": [],
+        "StaticWorldHeldStats": [],
+        "Stats": [],
+        "Alterations": [],
+        "LivingItemSlots": []
+      },
+      "DatabaseGUID": "",
+      "ItemOwnerLookupId": -1,
+      "RuntimeTags": {
+        "GameplayTags": []
+      }
+    },
+    "Outputs": [
+      {
+        "Element": {
+          "RowName": "None",
+          "DataTableName": "D_ItemTemplate"
+        },
+        "Count": 1,
+        "DynamicProperties": []
+      }
+    ],
+    "ResourceOutputs": [],
+    "Refundable": "Inherit",
+    "ExperienceMultiplier": 1,
+    "Audio": {
+      "RowName": "None",
+      "DataTableName": "D_CraftingAudioData"
+    }
+  },
+  "Rows": [
+    {
+      "Name": "Biofuel1",
+      "RecipeSets": [
+        {
+          "RowName": "Composter",
+          "DataTableName": "D_RecipeSets"
+        }
+      ],
+      "Inputs": [
+        {
+          "Element": {
+            "RowName": "Raw_Meat",
+            "DataTableName": "D_ItemsStatic"
+          },
+          "Count": 2,
+          "DynamicProperties": []
+        },
+        {
+          "Element": {
+            "RowName": "Tree_Sap",
+            "DataTableName": "D_ItemsStatic"
+          },
+          "Count": 1,
+          "DynamicProperties": []
+        }
+      ],
+      "Outputs": [],
+      "Audio": {
+        "RowName": "Composter"
+      },
+      "ResourceOutputs": [
+        {
+          "Type": {
+            "Value": "Biofuel"
+          },
+          "RequiredUnits": 100
+        }
+      ]
+    }
+  ]
+}
+  `
+
+	expected := `
+{
+  "RowStruct": "/Script/Icarus.ProcessorRecipe",
+  "Defaults": {
+    "bForceDisableRecipe": false,
+    "Requirement": {
+      "RowName": "None",
+      "DataTableName": "D_Talents"
+    },
+    "SessionRequirement": {
+      "RowName": "None",
+      "DataTableName": "D_CharacterFlags"
+    },
+    "CharacterRequirement": {
+      "RowName": "None",
+      "DataTableName": "D_CharacterFlags"
+    },
+    "RequiredMillijoules": 2500,
+    "RecipeSets": [],
+    "ResourceCostMultipliers": [],
+    "Inputs": [
+      {
+        "Element": {
+          "RowName": "None",
+          "DataTableName": "D_ItemsStatic"
+        },
+        "Count": 1,
+        "DynamicProperties": []
+      }
+    ],
+    "Container": {
+      "Value": "None"
+    },
+    "ResourceInputs": [],
+    "bSelectOutputItemRandomly": false,
+    "bContainsContainer": false,
+    "ItemIconOverride": {
+      "ItemStaticData": {
+        "RowName": "None",
+        "DataTableName": "D_ItemsStatic"
+      },
+      "ItemDynamicData": [],
+      "ItemCustomStats": [],
+      "CustomProperties": {
+        "StaticWorldStats": [],
+        "StaticWorldHeldStats": [],
+        "Stats": [],
+        "Alterations": [],
+        "LivingItemSlots": []
+      },
+      "DatabaseGUID": "",
+      "ItemOwnerLookupId": -1,
+      "RuntimeTags": {
+        "GameplayTags": []
+      }
+    },
+    "Outputs": [
+      {
+        "Element": {
+          "RowName": "None",
+          "DataTableName": "D_ItemTemplate"
+        },
+        "Count": 1,
+        "DynamicProperties": []
+      }
+    ],
+    "ResourceOutputs": [],
+    "Refundable": "Inherit",
+    "ExperienceMultiplier": 1,
+    "Audio": {
+      "RowName": "None",
+      "DataTableName": "D_CraftingAudioData"
+    }
+  },
+  "Rows": [
+    {
+      "Name": "Biofuel1",
+      "RecipeSets": [
+        {
+          "RowName": "Composter",
+          "DataTableName": "D_RecipeSets"
+        }
+      ],
+      "Inputs": [
+        {
+          "Element": {
+            "RowName": "Raw_Meat",
+            "DataTableName": "D_ItemsStatic"
+          },
+          "Count": 2,
+          "DynamicProperties": []
+        }
+      ],
+      "Outputs": [],
+      "Audio": {
+        "RowName": "Composter"
+      },
+      "ResourceOutputs": [
+        {
+          "Type": {
+            "Value": "Biofuel"
+          },
+          "RequiredUnits": 100
+        }
+      ]
+    }
+  ]
+}
+  `
+
+	command := utils.ModifyCommand{
+		Name: "test",
+		Lua: `
+    -- Define regex patterns for matching recipe names
+    local function matchesPattern(name, pattern)
+      local matches = re(pattern, name)
+      -- Check if matches table has any content (index 0 or 1 should exist if there's a match)
+      return matches and (matches[0] or matches[1])
+    end
+
+    -- Selection pattern for recipes that get multiplied
+    local selectionPattern = "(?-s)(Bulk_)?(Pistol|Rifle).*?Round.*?|(Carbon|Composite)_Paste.*|(Gold|Copper)_Wire|(Ironw|Copper)_Nail|(Platinum|Steel|Cold_Steel|Titanium)_Ingot|.*?Shotgun_Shell.*?|.*_Arrow|.*_Bolt|.*_Fertilizer_?\\d*|.*_Grenade|.*_Pill|.*_Tonic|Aluminum|Ammo_Casing|Animal_Fat|Carbon_Fiber|Composites|Concrete_Mix|Cured_Leather_?\\d?|Electronics|Epoxy_?\\d?|Glass\\d?|Gunpowder\\w*|Health_.*|Titanium_Plate|Organic_Resin|Platinum_Sheath|Refined_[a-zA-Z]+|Rope|Shotgun_Casing|Steel_Bloom\\d?|Tree_Sap\\w*"
+
+    -- Ingot pattern for recipes that get count set to 1
+    local ingotPattern = "(?-s)(Platinum|Steel|Cold_Steel|Titanium)_Ingot|Aluminum|Refined_[a-zA-Z]+|Glass\\d?"
+
+    local factor = 16
+    local bonus = 0.5
+
+    for _, row in ipairs(data.Rows) do
+      local recipeName = row.Name
+
+      -- Special case: Biofuel recipes - remove Tree_Sap input
+      if string.find(recipeName, "Biofuel") then
+        if row.Inputs then
+          for i = #row.Inputs, 1, -1 do
+            local input = row.Inputs[i]
+            if input.Element and input.Element.RowName and string.find(input.Element.RowName, "Tree_Sap") then
+              table.remove(row.Inputs, i)
+              print("Removing input 'Tree_Sap' from processor recipe '" .. recipeName .. "'")
+            end
+          end
+        end
+      end
+
+      -- Ingot recipes: set input and output counts to 1
+      if matchesPattern(recipeName, ingotPattern) then
+        if row.Inputs then
+          for _, input in ipairs(row.Inputs) do
+            input.Count = 1
+          end
+        end
+        if row.Outputs then
+          for _, output in ipairs(row.Outputs) do
+            output.Count = 1
+          end
+        end
+      end
+
+      -- Selected recipes: multiply inputs by factor, outputs by factor * (1 + bonus)
+      if matchesPattern(recipeName, selectionPattern) then
+        if row.Inputs then
+          for _, input in ipairs(row.Inputs) do
+            local oldCount = input.Count
+            input.Count = input.Count * factor
+            print("Recipe " .. recipeName .. " Input.Count: " .. oldCount .. " -> " .. input.Count)
+          end
+        end
+
+        if row.Outputs then
+          for _, output in ipairs(row.Outputs) do
+            local oldCount = output.Count
+            output.Count = math.floor(output.Count * factor * (1 + bonus))
+            print("Recipe " .. recipeName .. " Output.Count: " .. oldCount .. " -> " .. output.Count)
+          end
+        end
+      end
+    end
+`,
+	}
+
+	commands, err := ProcessJSON(content, command, "test.json")
+	if err != nil {
+		t.Fatalf("ProcessJSON failed: %v", err)
+	}
+
+	if len(commands) == 0 {
+		t.Fatal("Expected at least one command")
+	}
+
+	// Apply the commands
+	result := content
+	for _, cmd := range commands {
+		result = result[:cmd.From] + cmd.With + result[cmd.To:]
+	}
+
+	diff := cmp.Diff(result, expected)
+	if diff != "" {
+		t.Errorf("Differences:\n%s", diff)
+	}
+
+	// Check that the result matches expected (preserves formatting and changes weight)
+	if result != expected {
+		t.Errorf("Expected:\n%s\n\nGot:\n%s", expected, result)
+	}
+}
+
+func TestRetardedJSONEditing(t *testing.T) {
+	original := `{
+  "RowStruct": "/Script/Icarus.ItemableData",
+  "Defaults": {
+    "Behaviour": "None",
+    "DisplayName": "",
+    "Icon": "None",
+    "Override_Glow_Icon": "None",
+    "Description": "",
+    "FlavorText": "",
+    "Weight": 0,
+    "bAllowZeroWeight": false,
+    "MaxStack": 1
+  },
+  "Rows": [
+		{
+      "DisplayName": "NSLOCTEXT(\"D_Itemable\", \"Item_Fiber-DisplayName\", \"Fiber\")",
+      "Icon": "/Game/Assets/2DArt/UI/Items/Item_Icons/Resources/ITEM_Fibre.ITEM_Fibre",
+      "Description": "NSLOCTEXT(\"D_Itemable\", \"Item_Fiber-Description\", \"A bundle of soft fiber, highly useful.\")",
+      "FlavorText": "NSLOCTEXT(\"D_Itemable\", \"Item_Fiber-FlavorText\", \"Fiber is collected from bast, the strong inner bark of certain flowering plants.\")",
+      "Weight": 10,
+      "MaxStack": 200,
+      "Name": "Item_Fiber"
+    }
+	]
+}`
+
+	expected := `{
+  "RowStruct": "/Script/Icarus.ItemableData",
+  "Defaults": {
+    "Behaviour": "None",
+    "DisplayName": "",
+    "Icon": "None",
+    "Override_Glow_Icon": "None",
+    "Description": "",
+    "FlavorText": "",
+    "Weight": 0,
+    "bAllowZeroWeight": false,
+    "MaxStack": 1
+  },
+  "Rows": [
+		{
+      "DisplayName": "NSLOCTEXT(\"D_Itemable\", \"Item_Fiber-DisplayName\", \"Fiber\")",
+      "Icon": "/Game/Assets/2DArt/UI/Items/Item_Icons/Resources/ITEM_Fibre.ITEM_Fibre",
+      "Description": "NSLOCTEXT(\"D_Itemable\", \"Item_Fiber-Description\", \"A bundle of soft fiber, highly useful.\")",
+      "FlavorText": "NSLOCTEXT(\"D_Itemable\", \"Item_Fiber-FlavorText\", \"Fiber is collected from bast, the strong inner bark of certain flowering plants.\")",
+      "Weight": 10,
+      "MaxStack": 1000000,
+      "Name": "Item_Fiber"
+    }
+	]
+}`
+
+	command := utils.ModifyCommand{
+		Name: "test",
+		Lua: `
+    for _, row in ipairs(data.Rows) do
+      if row.MaxStack then
+        if string.find(row.Name, "Carrot") or string.find(row.Name, "Potato") then
+          row.MaxStack = 25
+        else
+          row.MaxStack = row.MaxStack * 10000
+          if row.MaxStack > 1000000 then
+            row.MaxStack = 1000000
+          end
+        end
+      end
+    end
+`,
+	}
+
+	commands, err := ProcessJSON(original, command, "test.json")
+	if err != nil {
+		t.Fatalf("ProcessJSON failed: %v", err)
+	}
+
+	if len(commands) == 0 {
+		t.Fatal("Expected at least one command")
+	}
+
+	// Apply the commands
+	result := original
+	for _, cmd := range commands {
+		result = result[:cmd.From] + cmd.With + result[cmd.To:]
+	}
+
+	diff := cmp.Diff(result, expected)
+	if diff != "" {
+		t.Errorf("Differences:\n%s", diff)
+	}
+
+	// Check that the weight was changed
+	if result != expected {
+		t.Errorf("Expected:\n%s\nGot:\n%s", expected, result)
+	}
+}
+
+func TestRetardedJSONEditing2(t *testing.T) {
+	original := `
+  {
+      "Rows": [
+        {
+            "Name": "Deep_Mining_Drill_Biofuel",
+            "Meshable": {
+                "RowName": "Mesh_Deep_Mining_Drill_Biofuel"
+            },
+            "Itemable": {
+                "RowName": "Item_Deep_Mining_Drill_Biofuel"
+            },
+            "Interactable": {
+                "RowName": "Deployable"
+            },
+            "Focusable": {
+                "RowName": "Focusable_1H"
+            },
+            "Highlightable": {
+                "RowName": "Generic"
+            },
+            "Actionable": {
+                "RowName": "Deployable"
+            },
+            "Usable": {
+                "RowName": "Place"
+            },
+            "Deployable": {
+                "RowName": "Deep_Mining_Drill_Biofuel"
+            },
+            "Durable": {
+                "RowName": "Deployable_750"
+            },
+            "Inventory": {
+                "RowName": "Deep_Mining_Drill_Biofuel"
+            },
+            "Decayable": {
+                "RowName": "Decay_MetaItem"
+            },
+            "Generator": {
+                "RowName": "Deep_Mining_Biofuel_Drill"
+            },
+            "Resource": {
+                "RowName": "Simple_Internal_Flow_Only"
+            },
+            "Manual_Tags": {
+                "GameplayTags": [
+                    {
+                        "TagName": "Item.Machine"
+                    }
+                ]
+            },
+            "Generated_Tags": {
+                "GameplayTags": [
+                    {
+                        "TagName": "Item.Machine"
+                    },
+                    {
+                        "TagName": "Traits.Meshable"
+                    },
+                    {
+                        "TagName": "Traits.Itemable"
+                    },
+                    {
+                        "TagName": "Traits.Interactable"
+                    },
+                    {
+                        "TagName": "Traits.Highlightable"
+                    },
+                    {
+                        "TagName": "Traits.Actionable"
+                    },
+                    {
+                        "TagName": "Traits.Usable"
+                    },
+                    {
+                        "TagName": "Traits.Deployable"
+                    },
+                    {
+                        "TagName": "Traits.Durable"
+                    },
+                    {
+                        "TagName": "Traits.Inventory"
+                    }
+                ],
+                "ParentTags": []
+            }
+        }
+      ]
+  }
+  `
+
+	expected := `
+  {
+      "Rows": [
+        {
+            "Name": "Deep_Mining_Drill_Biofuel",
+            "Meshable": {
+                "RowName": "Mesh_Deep_Mining_Drill_Biofuel"
+            },
+            "Itemable": {
+                "RowName": "Item_Deep_Mining_Drill_Biofuel"
+            },
+            "Interactable": {
+                "RowName": "Deployable"
+            },
+            "Focusable": {
+                "RowName": "Focusable_1H"
+            },
+            "Highlightable": {
+                "RowName": "Generic"
+            },
+            "Actionable": {
+                "RowName": "Deployable"
+            },
+            "Usable": {
+                "RowName": "Place"
+            },
+            "Deployable": {
+                "RowName": "Deep_Mining_Drill_Biofuel"
+            },
+            "Durable": {
+                "RowName": "Deployable_750"
+            },
+            "Inventory": {
+                "RowName": "Deep_Mining_Drill_Biofuel"
+            },
+            "Decayable": {
+                "RowName": "Decay_MetaItem"
+            },
+            "Generator": {
+                "RowName": "Deep_Mining_Biofuel_Drill"
+            },
+            "Resource": {
+                "RowName": "Simple_Internal_Flow_Only"
+            },
+            "Manual_Tags": {
+                "GameplayTags": [
+                    {
+                        "TagName": "Item.Machine"
+                    }
+                ]
+            },
+            "Generated_Tags": {
+                "GameplayTags": [
+                    {
+                        "TagName": "Item.Machine"
+                    },
+                    {
+                        "TagName": "Traits.Meshable"
+                    },
+                    {
+                        "TagName": "Traits.Itemable"
+                    },
+                    {
+                        "TagName": "Traits.Interactable"
+                    },
+                    {
+                        "TagName": "Traits.Highlightable"
+                    },
+                    {
+                        "TagName": "Traits.Actionable"
+                    },
+                    {
+                        "TagName": "Traits.Usable"
+                    },
+                    {
+                        "TagName": "Traits.Deployable"
+                    },
+                    {
+                        "TagName": "Traits.Durable"
+                    },
+                    {
+                        "TagName": "Traits.Inventory"
+                    }
+                ],
+                "ParentTags": []
+            }
+        ,"AdditionalStats": {"(Value=\"BaseDeepMiningDrillSpeed_+%\")":4000}}
+      ]
+  }
+  `
+
+	command := utils.ModifyCommand{
+		Name: "test",
+		Lua: `
+    for i, row in ipairs(data.Rows) do
+      -- Special case: Deep_Mining_Drill_Biofuel
+      if string.find(row.Name, "Deep_Mining_Drill_Biofuel") then
+        print("[DEBUG]  Special case: Deep_Mining_Drill_Biofuel")
+        if not row.AdditionalStats then
+          print("[DEBUG]   Creating AdditionalStats table for Deep_Mining_Drill_Biofuel")
+          row.AdditionalStats = {}
+        end
+        print("[DEBUG]   Setting BaseDeepMiningDrillSpeed_+% to 4000")
+        row.AdditionalStats["(Value=\\\"BaseDeepMiningDrillSpeed_+%\\\")"] = 4000
+      end
+    end
+`,
+	}
+
+	commands, err := ProcessJSON(original, command, "test.json")
+	if err != nil {
+		t.Fatalf("ProcessJSON failed: %v", err)
+	}
+
+	if len(commands) == 0 {
+		t.Fatal("Expected at least one command")
+	}
+
+	// Apply the commands
+	result := original
+	for _, cmd := range commands {
+		result = result[:cmd.From] + cmd.With + result[cmd.To:]
+	}
+
+	diff := cmp.Diff(result, expected)
+	if diff != "" {
+		t.Errorf("Differences:\n%s", diff)
+	}
+
+	if result != expected {
+		t.Errorf("Expected:\n%s\nGot:\n%s", expected, result)
+	}
+}

test_surgical.yml

@@ -0,0 +1,11 @@
+- name: SurgicalWeightTest
+  json: true
+  lua: |
+    -- This demonstrates surgical JSON editing
+    -- Only the Weight field of Item_Fiber will be modified
+    data.Rows[1].Weight = 999
+    modified = true
+  files:
+    - 'D_Itemable.json'
+  reset: false
+  loglevel: INFO 

utils/db.go

@@ -7,6 +7,7 @@ import (
 	logger "git.site.quack-lab.dev/dave/cylogger"
 	"gorm.io/driver/sqlite"
 	"gorm.io/gorm"
+	gormlogger "gorm.io/gorm/logger"
 )
 
 // dbLogger is a scoped logger for the utils/db package.
@@ -43,7 +44,7 @@ func GetDB() (DB, error) {
 	db, err := gorm.Open(sqlite.Open(dbFile), &gorm.Config{
 		// SkipDefaultTransaction: true,
 		PrepareStmt: true,
-		// Logger:      gormlogger.Default.LogMode(gormlogger.Silent),
+		Logger:      gormlogger.Default.LogMode(gormlogger.Silent),
 	})
 	if err != nil {
 		getDBLogger.Error("Failed to open database: %v", err)
@@ -120,7 +121,8 @@ func (db *DBWrapper) GetFile(filePath string) ([]byte, error) {
 	var fileSnapshot FileSnapshot
 	err := db.db.Model(&FileSnapshot{}).Where("file_path = ?", filePath).First(&fileSnapshot).Error
 	if err != nil {
-		getFileLogger.Error("Failed to get file from database: %v", err)
+		// Downgrade not-found to warning to avoid noisy errors during first run
+		getFileLogger.Warning("Failed to get file from database: %v", err)
 		return nil, err
 	}
 	getFileLogger.Debug("File found in database")

utils/file.go

@@ -102,7 +102,17 @@ func ResetWhereNecessary(associations map[string]FileCommandAssociation, db DB)
 		fileData, err := db.GetFile(file)
 		if err != nil {
 			resetWhereNecessaryLogger.Warning("Failed to get original content for file %q from database: %v", file, err)
-			continue
+			// Seed the snapshot from current disk content if missing, then use it as fallback
+			currentData, readErr := os.ReadFile(file)
+			if readErr != nil {
+				resetWhereNecessaryLogger.Warning("Additionally failed to read current file content for %q: %v", file, readErr)
+				continue
+			}
+			// Best-effort attempt to save baseline; ignore errors to avoid blocking reset
+			if saveErr := db.SaveFile(file, currentData); saveErr != nil {
+				resetWhereNecessaryLogger.Warning("Failed to seed baseline snapshot for %q: %v", file, saveErr)
+			}
+			fileData = currentData
 		}
 		resetWhereNecessaryLogger.Trace("Retrieved original file data length for %q: %d", file, len(fileData))
 		resetWhereNecessaryLogger.Debug("Writing original content back to file %q", file)

utils/flags.go

@@ -12,9 +12,10 @@ var flagsLogger = logger.Default.WithPrefix("utils/flags")
 var (
 	ParallelFiles = flag.Int("P", 100, "Number of files to process in parallel")
 	Filter        = flag.String("f", "", "Filter commands before running them")
+	JSON          = flag.Bool("json", false, "Enable JSON mode for processing JSON files")
 )
 
 func init() {
 	flagsLogger.Debug("Initializing flags")
-	flagsLogger.Trace("ParallelFiles initial value: %d, Filter initial value: %q", *ParallelFiles, *Filter)
+	flagsLogger.Trace("ParallelFiles initial value: %d, Filter initial value: %q, JSON initial value: %t", *ParallelFiles, *Filter, *JSON)
 }

utils/modifycommand.go

@@ -25,6 +25,7 @@ type ModifyCommand struct {
 	Isolate   bool                   `yaml:"isolate,omitempty"`
 	NoDedup   bool                   `yaml:"nodedup,omitempty"`
 	Disabled  bool                   `yaml:"disable,omitempty"`
+	JSON      bool                   `yaml:"json,omitempty"`
 	Modifiers map[string]interface{} `yaml:"modifiers,omitempty"`
 }
 
@@ -33,10 +34,15 @@ type CookFile []ModifyCommand
 func (c *ModifyCommand) Validate() error {
 	validateLogger := modifyCommandLogger.WithPrefix("Validate").WithField("commandName", c.Name)
 	validateLogger.Debug("Validating command")
-	if c.Regex == "" && len(c.Regexes) == 0 {
+
-		validateLogger.Error("Validation failed: Regex pattern is required")
+	// For JSON mode, regex patterns are not required
-		return fmt.Errorf("pattern is required")
+	if !c.JSON {
+		if c.Regex == "" && len(c.Regexes) == 0 {
+			validateLogger.Error("Validation failed: Regex pattern is required for non-JSON mode")
+			return fmt.Errorf("pattern is required for non-JSON mode")
+		}
 	}
+
 	if c.Lua == "" {
 		validateLogger.Error("Validation failed: Lua expression is required")
 		return fmt.Errorf("lua expression is required")