feat(agent): implement tool calling in agent mode

Add support for Grok to call tools (edit, scaffold, testgen, lint, commit) via JSON in ```tool blocks.
Introduce HandleToolCall to parse and execute tool requests, integrating with existing commands.
Update system prompt and chat loop to handle tool calls and feed results back.

cmd/chat.go

@@ -12,6 +12,7 @@ import (
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
 	"gmgauthier.com/grokkit/config"
+	"gmgauthier.com/grokkit/internal/agent"
 	"gmgauthier.com/grokkit/internal/grok"
 )
 
@@ -97,10 +98,15 @@ func runChat(cmd *cobra.Command, args []string) {
 	}
 
 	if agentMode {
-		systemPrompt["content"] = `You are Grok in Agent Mode.
-You have access to tools: edit, scaffold, testgen, lint, commit, etc.
-Always use tools when the user wants you to change code, generate tests, lint or commit.
-Be concise and action-oriented. After every tool call, wait for the result.`
+		systemPrompt["content"] = "You are Grok in Agent Mode.\n" +
+			"You can call tools using this exact JSON format inside ```tool blocks:\n\n" +
+			"```tool\n" +
+			"{\"tool\": \"edit\", \"file\": \"main.go\", \"instruction\": \"Add error handling\"}\n" +
+			"```\n\n" +
+			"Available tools: edit, scaffold, testgen, lint, commit.\n\n" +
+			"Always use tools when the user asks you to change code, generate tests, lint, or commit.\n" +
+			"After every tool call, wait for the result before continuing.\n" +
+			"Be concise and action-oriented."
 	}
 
 	history := loadChatHistory()
@@ -138,6 +144,15 @@ Be concise and action-oriented. After every tool call, wait for the result.`
 		color.Green("Grok > ")
 		reply := client.Stream(history, model)
 
+		// Agent mode: check for tool calls
+		if agentMode && strings.Contains(reply, "```tool") {
+			agent.HandleToolCall(reply, &history, model)
+			continue
+		}
+
+		history = append(history, map[string]string{"role": "assistant", "content": reply})
+		_ = saveChatHistory(history)
+
 		history = append(history, map[string]string{"role": "assistant", "content": reply})
 		_ = saveChatHistory(history)
 

internal/agent/tools.go

@@ -0,0 +1,95 @@
+package agent
+
+import (
+	"encoding/json"
+	_ "fmt"
+	"strings"
+
+	"github.com/fatih/color"
+	"gmgauthier.com/grokkit/cmd"
+	"gmgauthier.com/grokkit/internal/git"
+)
+
+// ToolCall represents a tool request from Grok
+type ToolCall struct {
+	Tool        string `json:"tool"`
+	File        string `json:"file,omitempty"`
+	Path        string `json:"path,omitempty"`
+	Instruction string `json:"instruction,omitempty"`
+	Description string `json:"description,omitempty"`
+	Message     string `json:"message,omitempty"`
+}
+
+// handleToolCall parses and executes tool calls from Grok's response
+func HandleToolCall(reply string, history *[]map[string]string, model string) {
+	// Look for ```tool ... ``` blocks
+	start := strings.Index(reply, "```tool")
+	if start == -1 {
+		return
+	}
+	end := strings.Index(reply[start:], "```")
+	if end == -1 {
+		return
+	}
+	block := strings.TrimSpace(reply[start+7 : start+end])
+
+	var tc ToolCall
+	if err := json.Unmarshal([]byte(block), &tc); err != nil {
+		color.Red("Failed to parse tool call: %v", err)
+		return
+	}
+
+	color.Yellow("\n[Agent] Grok wants to call tool: %s", tc.Tool)
+
+	switch tc.Tool {
+	case "edit":
+		if tc.File == "" || tc.Instruction == "" {
+			color.Red("Invalid edit call — missing file or instruction")
+			break
+		}
+		color.Cyan("Editing %s with instruction: %s", tc.File, tc.Instruction)
+		// Reuse the existing edit flow (it already does preview + confirm)
+		cmd.RunEditWithInstruction(tc.File, tc.Instruction)
+
+	case "scaffold":
+		if tc.Path == "" || tc.Description == "" {
+			color.Red("Invalid scaffold call")
+			break
+		}
+		color.Cyan("Scaffolding %s: %s", tc.Path, tc.Description)
+		cmd.RunScaffoldWithDescription(tc.Path, tc.Description)
+
+	case "testgen":
+		if tc.File == "" {
+			color.Red("Invalid testgen call")
+			break
+		}
+		color.Cyan("Generating tests for %s", tc.File)
+		cmd.RunTestgenWithFile(tc.File)
+
+	case "lint":
+		if tc.File == "" {
+			color.Red("Invalid lint call")
+			break
+		}
+		color.Cyan("Linting %s", tc.File)
+		cmd.RunLintWithFile(tc.File)
+
+	case "commit":
+		if tc.Message == "" {
+			color.Red("Invalid commit call")
+			break
+		}
+		color.Cyan("Committing with message: %s", tc.Message)
+		git.Run([]string{"commit", "-m", tc.Message})
+
+	default:
+		color.Red("Unknown tool: %s", tc.Tool)
+	}
+
+	// Feed result back to Grok
+	*history = append(*history, map[string]string{
+		"role":    "assistant",
+		"content": reply,
+	})
+}