Harden Sentry agent prompt and fix branch detection

The agent prompt was too verbose and the LLM ignored the 'do NOT use
project_map' instruction, wasting 12 tool calls exploring the project
instead of fixing the bug. The PR command also hardcoded --base master
instead of detecting the default branch.

Rewrote the prompt to be terser and imperative. Detects the default
branch from the cloned repo via git rev-parse. Uses a unique branch
name per run to avoid conflicts. The PR is the final mandatory step.

Author: Test

cmd/gptcode/agent.go

@@ -0,0 +1,206 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+
+	"github.com/spf13/cobra"
+	
+	"gptcode/internal/live"
+	"gptcode/internal/llm"
+	"gptcode/internal/modes"
+)
+
+var agentCmd = &cobra.Command{
+	Use:   "agent",
+	Short: "Run gptcode as a centralized autofix agent",
+	Long: `This command is intended to be run exclusively by the gptcode-live centralized agent system.
+It expects specific environment variables to authenticate and clone a shallow copy of the repository,
+fetch the CI logs, run the fix, and report back via WebSocket.`,
+	RunE: runAgent,
+}
+
+func init() {
+	rootCmd.AddCommand(agentCmd)
+}
+
+func runAgent(cmd *cobra.Command, args []string) error {
+	repo := os.Getenv("REPO")
+	branch := os.Getenv("BRANCH")
+	sha := os.Getenv("SHA")
+	runID := os.Getenv("RUN_ID")
+	token := os.Getenv("INSTALL_TOKEN")
+	liveURL := os.Getenv("GPTCODE_LIVE_URL")
+	agentID := os.Getenv("AGENT_ID")
+
+	if repo == "" || branch == "" || sha == "" || runID == "" || token == "" {
+		return fmt.Errorf("missing required agent environment variables (REPO, BRANCH, SHA, RUN_ID, INSTALL_TOKEN)")
+	}
+
+	fmt.Printf("🚀 Starting AutoFix Agent for %s@%s (Run %s)\n", repo, branch, runID)
+	if liveURL != "" {
+		fmt.Printf("📡 Reporting progress to %s with agent_id %s\n", liveURL, agentID)
+	}
+
+	// 1. Shallow clone the target repo using the installation token
+	cloneDir := "/work"
+	// Ensure directory doesn't exist from a previous run
+	os.RemoveAll(cloneDir)
+
+	repoURL := fmt.Sprintf("https://x-access-token:%s@github.com/%s.git", token, repo)
+	
+	fmt.Printf("📦 Cloning %s (branch: %s) into %s...\n", repo, branch, cloneDir)
+	cmdClone := exec.Command("git", "clone", "--depth", "1", "--branch", branch, repoURL, cloneDir)
+	cmdClone.Stdout = os.Stdout
+	cmdClone.Stderr = os.Stderr
+	err := cmdClone.Run()
+	if err != nil {
+		// Fallback: try 'master' if the specified branch doesn't exist
+		fmt.Printf("⚠️  Branch '%s' not found, trying 'master'...\n", branch)
+		os.RemoveAll(cloneDir)
+		cmdClone2 := exec.Command("git", "clone", "--depth", "1", "--branch", "master", repoURL, cloneDir)
+		cmdClone2.Stdout = os.Stdout
+		cmdClone2.Stderr = os.Stderr
+		err = cmdClone2.Run()
+		if err != nil {
+			// Final fallback: clone default branch
+			fmt.Printf("⚠️  Branch 'master' not found either, cloning default branch...\n")
+			os.RemoveAll(cloneDir)
+			cmdClone3 := exec.Command("git", "clone", "--depth", "1", repoURL, cloneDir)
+			cmdClone3.Stdout = os.Stdout
+			cmdClone3.Stderr = os.Stderr
+			err = cmdClone3.Run()
+			if err != nil {
+				fmt.Printf("❌ Failed to clone repository: %v\n", err)
+				return err
+			}
+		}
+	}
+	defer os.RemoveAll(cloneDir) // Clean up if running locally, though ephemeral VMs will just die
+
+	// Set GH_TOKEN so the gh CLI can create PRs
+	os.Setenv("GH_TOKEN", token)
+	// Configure git identity for commits
+	exec.Command("git", "config", "--global", "user.email", "gptcode-agent@zapfy.ai").Run()
+	exec.Command("git", "config", "--global", "user.name", "GPTCode Agent").Run()
+
+	// Change to the working directory
+	err = os.Chdir(cloneDir)
+	if err != nil {
+		return fmt.Errorf("failed to change to working directory %s: %w", cloneDir, err)
+	}
+
+	// 2. Extract contextual instruction
+	agentType := os.Getenv("AGENT_TYPE")
+	if agentType == "" {
+		agentType = "ci"
+	}
+
+	// Skip validation for Sentry agents — CI/CD will handle compilation
+	if agentType == "sentry" {
+		os.Setenv("SKIP_VALIDATION", "1")
+	}
+
+	var prompt string
+	if agentType == "sentry" {
+		sentryTitle := os.Getenv("SENTRY_TITLE")
+		sentryStack := os.Getenv("SENTRY_STACKTRACE")
+
+		// Detect default branch from the cloned repo
+		defaultBranch := "main"
+		if out, err := exec.Command("git", "rev-parse", "--abbrev-ref", "HEAD").Output(); err == nil {
+			if b := strings.TrimSpace(string(out)); b != "" {
+				defaultBranch = b
+			}
+		}
+
+		branchName := fmt.Sprintf("fix/sentry-%s", runID)
+
+		prompt = fmt.Sprintf(`You are a production bug-fix agent. A runtime error was caught by Sentry.
+
+ERROR: %s
+
+STACKTRACE:
+%s
+
+INSTRUCTIONS — follow EXACTLY in order:
+
+1. Use search_code to find the file mentioned in the stacktrace.
+2. Use read_file to read that file.
+3. Identify the bug. Apply a MINIMAL fix using apply_patch or write_file.
+4. Use run_command to create a branch, commit, push, and open a PR:
+
+   git checkout -b %s && \
+   git add -A && \
+   git commit -m "fix: %s" && \
+   git push origin %s && \
+   gh pr create --title "fix: %s" --body "Automated fix for Sentry error: %s" --base %s
+
+RULES:
+- Fix ONE file only. Do NOT refactor, do NOT write tests.
+- Do NOT run mix, npm, go build, or any build/test commands.
+- Do NOT explore the project. Go directly to the file from the stacktrace.
+- If you cannot identify the file from the stacktrace, use search_code with a key term from the error.
+- You MUST create the PR. The task is NOT complete until the PR is created.`,
+			sentryTitle, sentryStack,
+			branchName, sentryTitle, branchName,
+			sentryTitle, sentryTitle, defaultBranch)
+	} else {
+		// Default to CI pipeline logic
+		prompt = fmt.Sprintf(`The CI pipeline just failed for this repository on branch '%s'.
+The failing commit is %s.
+
+Please discover what failed by examining the code, tests, and standard CI configurations
+(such as npm test, mix test, go test, etc.) and write a fix. Once fixed, create a PR.`, branch, sha)
+	}
+
+	ctx := context.Background()
+
+	backendName := "openrouter"
+	baseURL := "https://openrouter.ai/api/v1"
+	provider := llm.NewChatCompletion(baseURL, backendName)
+
+	language := "elixir" // Most Zapfy repos are Elixir
+	queryModel := os.Getenv("MODEL")
+	if queryModel == "" {
+		queryModel = "anthropic/claude-sonnet-4"
+	}
+	
+	liveClient := live.GetClient()
+	var reportConfig *live.ReportConfig
+	if liveURL != "" {
+		reportConfig = live.DefaultReportConfig()
+		reportConfig.SetBaseURL(liveURL)
+		reportConfig.AgentID = agentID
+		
+		// Register on the Live Dashboard BEFORE starting execution
+		taskLabel := "Sentry Exception Repair"
+		if agentType != "sentry" {
+			taskLabel = "CI Breakdown Repair"
+		}
+		reportConfig.Model = queryModel
+		if err := reportConfig.Connect(agentID, agentType, taskLabel); err != nil {
+			fmt.Printf("⚠️  Live Dashboard connect failed (non-fatal): %v\n", err)
+		} else {
+			fmt.Printf("📡 Connected to Live Dashboard as %s\n", agentID)
+		}
+	} else if liveClient != nil {
+		reportConfig = live.DefaultReportConfig()
+		reportConfig.AgentID = live.GetAgentID()
+	}
+
+	executor := modes.NewAutonomousExecutorWithLive(provider, cloneDir, queryModel, language, liveClient, reportConfig, backendName)
+	
+	fmt.Println("🤖 Starting AutoFix process...")
+	err = executor.Execute(ctx, prompt)
+	if err != nil {
+		fmt.Printf("❌ AutoFix failed: %v\n", err)
+		return err
+	}
+
+	fmt.Println("✅ AutoFix completed successfully.")
+	return nil
+}