feat: initial scaffold of agent_runner_api service Go :8486

agent_spawn.go

@@ -0,0 +1,143 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"time"
+)
+
+type SpawnConfig struct {
+	RepoRoot     string
+	Branch       string
+	WorktreePath string
+	Prompt       string
+	LogPath      string
+}
+
+type SpawnResult struct {
+	PID          int    `json:"pid"`
+	Branch       string `json:"branch"`
+	WorktreePath string `json:"worktree_path"`
+	LogPath      string `json:"log_path"`
+	StartedAt    int64  `json:"started_at"`
+	Error        string `json:"error,omitempty"`
+}
+
+// Spawn creates a git worktree on a fresh branch (reset if exists) and starts
+// the claude headless subprocess. If claude is not in PATH or
+// AGENT_RUNNER_STUB=1, runs `echo STUB: <prompt>` as a placeholder.
+func Spawn(cfg SpawnConfig) SpawnResult {
+	res := SpawnResult{
+		Branch:       cfg.Branch,
+		WorktreePath: cfg.WorktreePath,
+		LogPath:      cfg.LogPath,
+		StartedAt:    time.Now().Unix(),
+	}
+
+	if cfg.RepoRoot == "" || cfg.Branch == "" || cfg.WorktreePath == "" {
+		res.Error = "missing required fields (repo_root/branch/worktree_path)"
+		return res
+	}
+
+	// Ensure parent dir for worktree exists
+	if err := os.MkdirAll(filepath.Dir(cfg.WorktreePath), 0o755); err != nil {
+		res.Error = "mkdir worktree parent: " + err.Error()
+		return res
+	}
+
+	// If worktree path already exists, remove forcibly first
+	if _, err := os.Stat(cfg.WorktreePath); err == nil {
+		_ = exec.Command("git", "-C", cfg.RepoRoot, "worktree", "remove", "--force", cfg.WorktreePath).Run()
+		_ = os.RemoveAll(cfg.WorktreePath)
+	}
+
+	// Delete branch if exists (best-effort)
+	_ = exec.Command("git", "-C", cfg.RepoRoot, "branch", "-D", cfg.Branch).Run()
+
+	// Create worktree on new branch from master (fallback to current HEAD if master missing)
+	base := "master"
+	if err := exec.Command("git", "-C", cfg.RepoRoot, "rev-parse", "--verify", base).Run(); err != nil {
+		base = "HEAD"
+	}
+	cmd := exec.Command("git", "-C", cfg.RepoRoot, "worktree", "add", "-b", cfg.Branch, cfg.WorktreePath, base)
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		res.Error = fmt.Sprintf("worktree add: %s: %s", err.Error(), string(out))
+		return res
+	}
+
+	// Open log
+	if cfg.LogPath == "" {
+		cfg.LogPath = filepath.Join(cfg.WorktreePath, "agent.log")
+		res.LogPath = cfg.LogPath
+	}
+	if err := os.MkdirAll(filepath.Dir(cfg.LogPath), 0o755); err != nil {
+		res.Error = "mkdir log: " + err.Error()
+		return res
+	}
+	logFile, err := os.OpenFile(cfg.LogPath, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0o644)
+	if err != nil {
+		res.Error = "open log: " + err.Error()
+		return res
+	}
+
+	// Decide command: claude or stub
+	useStub := os.Getenv("AGENT_RUNNER_STUB") == "1"
+	if !useStub {
+		if _, err := exec.LookPath("claude"); err != nil {
+			useStub = true
+		}
+	}
+
+	var sub *exec.Cmd
+	if useStub {
+		sub = exec.Command("echo", "STUB:", cfg.Prompt)
+	} else {
+		sub = exec.Command("claude", "--headless", "--dangerously-skip-permissions", "-p", cfg.Prompt)
+		sub.Dir = cfg.WorktreePath
+	}
+	if sub.Dir == "" {
+		sub.Dir = cfg.WorktreePath
+	}
+	sub.Stdout = logFile
+	sub.Stderr = logFile
+
+	if err := sub.Start(); err != nil {
+		logFile.Close()
+		res.Error = "spawn: " + err.Error()
+		return res
+	}
+	res.PID = sub.Process.Pid
+
+	// Reap async — closes log when subprocess exits
+	go func() {
+		_ = sub.Wait()
+		_ = logFile.Close()
+	}()
+
+	return res
+}
+
+// Cleanup kills the PID (best-effort), removes the worktree and deletes the branch.
+func Cleanup(repoRoot string, pid int, worktreePath, branch string) error {
+	var firstErr error
+	if pid > 0 {
+		if p, err := os.FindProcess(pid); err == nil {
+			_ = p.Kill()
+		}
+	}
+	if worktreePath != "" {
+		out, err := exec.Command("git", "-C", repoRoot, "worktree", "remove", "--force", worktreePath).CombinedOutput()
+		if err != nil && !strings.Contains(string(out), "is not a working tree") {
+			firstErr = fmt.Errorf("worktree remove: %s: %s", err.Error(), string(out))
+		}
+		_ = os.RemoveAll(worktreePath)
+	}
+	if branch != "" {
+		_ = exec.Command("git", "-C", repoRoot, "branch", "-D", branch).Run()
+	}
+	return firstErr
+}