Add M0 server skeleton with SQLite store, SSE events, worktrees, and tailscale service

internal/git/git.go

@@ -0,0 +1,86 @@
+package git
+
+import (
+	"fmt"
+	"os/exec"
+	"path/filepath"
+	"strings"
+)
+
+type RepoInfo struct {
+	Root          string
+	DefaultBranch string
+	Remote        string
+}
+
+func Inspect(path string) (RepoInfo, error) {
+	abs, err := filepath.Abs(path)
+	if err != nil {
+		return RepoInfo{}, err
+	}
+
+	root, err := run(abs, "rev-parse", "--show-toplevel")
+	if err != nil {
+		return RepoInfo{}, err
+	}
+
+	root, err = filepath.EvalSymlinks(root)
+	if err != nil {
+		return RepoInfo{}, err
+	}
+
+	abs, err = filepath.EvalSymlinks(abs)
+	if err != nil {
+		return RepoInfo{}, err
+	}
+
+	if root != abs {
+		return RepoInfo{}, fmt.Errorf("%s is inside the repo at %s; register the repo root", abs, root)
+	}
+
+	branch, err := run(root, "symbolic-ref", "--short", "HEAD")
+	if err != nil {
+		return RepoInfo{}, err
+	}
+
+	remote, err := run(root, "remote", "get-url", "origin")
+	if err != nil {
+		return RepoInfo{}, err
+	}
+
+	return RepoInfo{Root: root, DefaultBranch: branch, Remote: remote}, nil
+}
+
+func AddWorktree(repo, path, branch, base string) (string, error) {
+	sha, err := run(repo, "rev-parse", "--verify", base+"^{commit}")
+	if err != nil {
+		return "", err
+	}
+
+	_, err = run(repo, "worktree", "add", "-b", branch, path, sha)
+	if err != nil {
+		return "", err
+	}
+
+	return sha, nil
+}
+
+func RemoveWorktree(repo, path, branch string) error {
+	_, err := run(repo, "worktree", "remove", "--force", path)
+	if err != nil {
+		return err
+	}
+
+	_, err = run(repo, "branch", "-D", branch)
+	return err
+}
+
+func run(dir string, args ...string) (string, error) {
+	cmd := exec.Command("git", args...)
+	cmd.Dir = dir
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		return "", fmt.Errorf("git %s: %w: %s", strings.Join(args, " "), err, strings.TrimSpace(string(out)))
+	}
+	return strings.TrimSpace(string(out)), nil
+}