first round of files

internal/domain/git/agit.go

@@ -0,0 +1,22 @@
+package git
+
+import "strings"
+
+// ParseAGitRef extracts target and source branch from an AGit push ref.
+// AGit refs follow the pattern: refs/for/<target>[/<source>]
+// Returns ("", "", false) if the ref is not an AGit ref.
+func ParseAGitRef(ref string) (target, source string, ok bool) {
+	const prefix = "refs/for/"
+	if !strings.HasPrefix(ref, prefix) {
+		return "", "", false
+	}
+	rest := strings.TrimPrefix(ref, prefix)
+	parts := strings.SplitN(rest, "/", 2)
+	target = parts[0]
+	if len(parts) == 2 {
+		source = parts[1]
+	} else {
+		source = target
+	}
+	return target, source, true
+}

internal/domain/git/binary.go

@@ -0,0 +1,113 @@
+package git
+
+import (
+	"errors"
+	"os/exec"
+	"path/filepath"
+	"strings"
+)
+
+var ErrPathTraversal = errors.New("repo path outside of configured root")
+
+var repoRoot string
+
+func SetRepoRoot(root string) {
+	repoRoot = filepath.Clean(root)
+}
+
+// run executes a git command inside repoPath with strict safety guarantees:
+// - repoPath is validated to be under the configured repoRoot
+// - args are passed as discrete values — never via shell interpolation
+// - the process inherits only a minimal environment
+func run(repoPath string, args ...string) ([]byte, error) {
+	clean := filepath.Clean(repoPath)
+	if repoRoot != "" && !strings.HasPrefix(clean, repoRoot+string(filepath.Separator)) && clean != repoRoot {
+		return nil, ErrPathTraversal
+	}
+
+	cmd := exec.Command("git", args...)
+	cmd.Dir = clean
+	cmd.Env = []string{
+		"GIT_TERMINAL_PROMPT=0",
+		"HOME=" + filepath.Dir(repoRoot), // needed for .gitconfig lookups
+	}
+	return cmd.Output()
+}
+
+func Init(path string) error {
+	_, err := run(path, "init", "--bare")
+	return err
+}
+
+type Commit struct {
+	Hash    string
+	Author  string
+	Message string
+	Date    string
+}
+
+func Log(repoPath, branch string, limit int) ([]Commit, error) {
+	out, err := run(repoPath, "log", branch,
+		"--format=%H\x1f%an\x1f%s\x1f%ci",
+		"--max-count", strings.TrimSpace(string(rune(limit+'0'))),
+	)
+	if err != nil {
+		return nil, err
+	}
+	var commits []Commit
+	for _, line := range strings.Split(strings.TrimSpace(string(out)), "\n") {
+		parts := strings.Split(line, "\x1f")
+		if len(parts) != 4 {
+			continue
+		}
+		commits = append(commits, Commit{
+			Hash:    parts[0],
+			Author:  parts[1],
+			Message: parts[2],
+			Date:    parts[3],
+		})
+	}
+	return commits, nil
+}
+
+type TreeEntry struct {
+	Mode string
+	Type string
+	Hash string
+	Name string
+}
+
+func TreeLS(repoPath, ref, subPath string) ([]TreeEntry, error) {
+	treeRef := ref + ":" + subPath
+	out, err := run(repoPath, "ls-tree", treeRef)
+	if err != nil {
+		return nil, err
+	}
+	var entries []TreeEntry
+	for _, line := range strings.Split(strings.TrimSpace(string(out)), "\n") {
+		if line == "" {
+			continue
+		}
+		// format: <mode> SP <type> SP <hash> TAB <name>
+		tabIdx := strings.Index(line, "\t")
+		if tabIdx < 0 {
+			continue
+		}
+		name := line[tabIdx+1:]
+		fields := strings.Fields(line[:tabIdx])
+		if len(fields) != 3 {
+			continue
+		}
+		entries = append(entries, TreeEntry{
+			Mode: fields[0],
+			Type: fields[1],
+			Hash: fields[2],
+			Name: name,
+		})
+	}
+	return entries, nil
+}
+
+func BlobCat(repoPath, ref, filePath string) ([]byte, error) {
+	return run(repoPath, "show", ref+":"+filePath)
+}