feat: build-on-node — git checkouts, remote image builds, image transport (#60)

Git-sourced deploys never materialized a checkout: sourcePath was
build_path resolved against the server cwd, so builds consumed the
backend's own directory. Remote placement could only run
registry-pulled images.

- internal/source: per-deployment checkout (init/fetch/checkout) at
  branch or commit; GIT_ASKPASS keeps tokens out of argv, .git/config,
  and the build context; dumb-transport and SHA-refusal fallbacks;
  build_path validated inside the checkout.
- BuildManager.PackageContext: produces the same tar context Build
  ships to the daemon — generated Dockerfile at tar root, .git
  excluded. Fixes nixpacks passing the Dockerfile path as content.
- Agent artifact endpoint: GET /api/agents/artifacts/:id streams
  build contexts and docker-save tarballs behind agent-token auth;
  hex-validated ids, per-deployment cleanup, boot-time purge.
- Agent commands: build_image (docker build -, --build-arg values via
  process env, not argv) and load_image (docker load for containr-*
  rollback tags no registry serves).
- Deployment flow: remote git builds package context → artifact →
  node docker-builds the deployment tag; remote rollbacks of local
  tags export via SaveImage → artifact → node docker-loads.

Verified end-to-end: agent-pinned git service built on the node
(build_image → create_container → deployed) and rollback shipped a
docker-save tarball (load_image → deployed). Artifact auth returns
401/404 correctly; workspaces and blobs are removed after deploy.

Authored By: TDvorak <[email protected]>

app/backend/internal/source/source_test.go

@@ -0,0 +1,152 @@
+package source
+
+import (
+	"context"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"testing"
+)
+
+func TestNormalizeCloneURL(t *testing.T) {
+	cases := []struct {
+		in, want string
+		err      bool
+	}{
+		{"https://github.com/org/repo.git", "https://github.com/org/repo.git", false},
+		{"[email protected]:org/repo.git", "https://github.com/org/repo.git", false},
+		{"ssh://[email protected]/org/repo.git", "https://gitlab.example.com/org/repo.git", false},
+		{"org/repo", "org/repo", false},
+		{"  https://gitlab.com/a/b.git  ", "https://gitlab.com/a/b.git", false},
+		{"", "", true},
+		{"ftp://example.com/repo", "", true},
+		{"weird string", "", true},
+	}
+	for _, c := range cases {
+		got, err := NormalizeCloneURL(c.in)
+		if c.err {
+			if err == nil {
+				t.Errorf("%q: expected error, got %q", c.in, got)
+			}
+			continue
+		}
+		if err != nil {
+			t.Errorf("%q: unexpected error %v", c.in, err)
+			continue
+		}
+		if got != c.want {
+			t.Errorf("%q: got %q, want %q", c.in, got, c.want)
+		}
+	}
+}
+
+func TestValidateRemoteURL(t *testing.T) {
+	if err := ValidateRemoteURL("https://github.com/o/r.git"); err != nil {
+		t.Errorf("https should pass: %v", err)
+	}
+	if err := ValidateRemoteURL("file:///tmp/repo"); err == nil {
+		t.Error("file:// should be rejected")
+	}
+	if err := ValidateRemoteURL("/tmp/repo"); err == nil {
+		t.Error("local path should be rejected")
+	}
+}
+
+// initRepo creates a small git repo with a branch and returns its path.
+func initRepo(t *testing.T) string {
+	t.Helper()
+	dir := t.TempDir()
+	run := func(args ...string) {
+		t.Helper()
+		cmd := exec.Command("git", args...)
+		cmd.Dir = dir
+		cmd.Env = append(os.Environ(),
+			"GIT_AUTHOR_NAME=t", "GIT_AUTHOR_EMAIL=t@t",
+			"GIT_COMMITTER_NAME=t", "GIT_COMMITTER_EMAIL=t@t")
+		if out, err := cmd.CombinedOutput(); err != nil {
+			t.Fatalf("git %v: %s", args, out)
+		}
+	}
+	run("init", "-q", "-b", "main")
+	if err := os.WriteFile(filepath.Join(dir, "app.txt"), []byte("v1"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.MkdirAll(filepath.Join(dir, "sub"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(dir, "sub", "inner.txt"), []byte("sub"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	run("add", ".")
+	run("commit", "-q", "-m", "first")
+	return dir
+}
+
+func TestCheckoutBranch(t *testing.T) {
+	if _, err := exec.LookPath("git"); err != nil {
+		t.Skip("git not available")
+	}
+	repo := initRepo(t)
+	dest := t.TempDir()
+	dir, err := Checkout(context.Background(), dest, Spec{CloneURL: repo, Branch: "main"})
+	if err != nil {
+		t.Fatalf("checkout: %v", err)
+	}
+	if _, err := os.Stat(filepath.Join(dir, "app.txt")); err != nil {
+		t.Errorf("expected app.txt in checkout: %v", err)
+	}
+}
+
+func TestCheckoutBuildPath(t *testing.T) {
+	if _, err := exec.LookPath("git"); err != nil {
+		t.Skip("git not available")
+	}
+	repo := initRepo(t)
+	dest := t.TempDir()
+	dir, err := Checkout(context.Background(), dest, Spec{CloneURL: repo, Branch: "main", BuildPath: "sub"})
+	if err != nil {
+		t.Fatalf("checkout: %v", err)
+	}
+	if filepath.Base(dir) != "sub" {
+		t.Errorf("expected sub build path, got %s", dir)
+	}
+	if _, err := os.Stat(filepath.Join(dir, "inner.txt")); err != nil {
+		t.Errorf("expected inner.txt under build path: %v", err)
+	}
+}
+
+func TestCheckoutCommit(t *testing.T) {
+	if _, err := exec.LookPath("git"); err != nil {
+		t.Skip("git not available")
+	}
+	repo := initRepo(t)
+	out, err := exec.Command("git", "-C", repo, "rev-parse", "HEAD").Output()
+	if err != nil {
+		t.Fatal(err)
+	}
+	sha := string(out[:len(out)-1])
+	dest := t.TempDir()
+	dir, err := Checkout(context.Background(), dest, Spec{CloneURL: repo, Commit: sha, Branch: "main"})
+	if err != nil {
+		t.Fatalf("checkout commit: %v", err)
+	}
+	if _, err := os.Stat(filepath.Join(dir, "app.txt")); err != nil {
+		t.Errorf("expected app.txt in pinned checkout: %v", err)
+	}
+}
+
+func TestResolveBuildPathEscapes(t *testing.T) {
+	root := t.TempDir()
+	if _, err := ResolveBuildPath(root, "../../etc"); err == nil {
+		t.Error("escape should be rejected")
+	}
+	if _, err := ResolveBuildPath(root, "/abs/path"); err == nil {
+		t.Error("absolute path should be rejected")
+	}
+	if _, err := ResolveBuildPath(root, "missing"); err == nil {
+		t.Error("missing dir should be rejected")
+	}
+	if got, err := ResolveBuildPath(root, "."); err != nil || got != root {
+		t.Errorf("dot should resolve to root, got %q err=%v", got, err)
+	}
+}