ComfyUI is installed by the agent, from its source checked against a digest

engines.comfyui in the cluster's settings has every NVIDIA node build
ComfyUI: the release's source archive from GitHub, checked against the
digest the recipe holds — GitHub publishes none for a tag's archive, so a
version without one is refused — unpacked beside a Python environment
whose dependencies are its requirements file resolved as PyPI stood the
day after the release. torch is PyPI's CUDA 13 build, or PyTorch's CUDA
12.9 one on an older driver, and the install is checked on the card.

A requirements file that names anything but PyPI packages is refused.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

internal/agent/provision/python.go

@@ -66,12 +66,17 @@ func (in *Installer) installPython(ctx context.Context, r Recipe, w Want, b Buil
 		return fmt.Errorf("installing uv, which installs %s: %s", w.Engine, uv.Detail)
 	}
 
-	in.progress(st, "asking PyPI when %s %s was published", r.PyPI, w.Version)
-	published, err := in.published(ctx, r.PyPI, w.Version)
-	if err != nil {
-		return err
+	var asOf string
+	if !b.AsOf.IsZero() {
+		asOf = b.AsOf.UTC().Format(time.RFC3339)
+	} else {
+		in.progress(st, "asking PyPI when %s %s was published", r.PyPI, w.Version)
+		published, err := in.published(ctx, r.PyPI, w.Version)
+		if err != nil {
+			return err
+		}
+		asOf = published.Add(24 * time.Hour).UTC().Format(time.RFC3339)
 	}
-	asOf := published.Add(24 * time.Hour).UTC().Format(time.RFC3339)
 
 	cache := filepath.Join(in.root(), ".uv-cache")
 	env := []string{
@@ -96,7 +101,14 @@ func (in *Installer) installPython(ctx context.Context, r Recipe, w Want, b Buil
 	}
 	python := filepath.Join(tmp, "bin", "python")
 
-	reqs := b.Requirements
+	reqs := slices.Clone(b.Requirements)
+	if b.Source != nil {
+		more, err := in.unpackSource(ctx, w, b, tmp, st)
+		if err != nil {
+			return err
+		}
+		reqs = append(reqs, more...)
+	}
 	if b.Wheel != nil {
 		// The engine from its GitHub release, pinned to the digest GitHub
 		// publishes for the file: the same trust as an archive, and uv
@@ -320,3 +332,68 @@ func (in *Installer) gpuCheck(ctx context.Context, python string, w Want, b Buil
 	}
 	return nil
 }
+
+// unpackSource fetches an engine's source archive, checks it against the
+// digest the recipe holds, puts its code in the environment, and returns the
+// requirements its requirements file names — less the packages a second
+// index gives, which the build names itself.
+func (in *Installer) unpackSource(ctx context.Context, w Want, b Build, env string, st *Status) ([]string, error) {
+	src := b.Source
+	url := src.URL
+	if strings.HasPrefix(url, "/") {
+		url = strings.TrimSuffix(in.downloadBase(), "/") + url
+	}
+	scratch := env + ".source"
+	_ = os.RemoveAll(scratch)
+	if err := os.MkdirAll(scratch, 0o755); err != nil {
+		return nil, err
+	}
+	defer os.RemoveAll(scratch) //nolint:errcheck // scratch
+	archive := filepath.Join(scratch, "source.tar.gz")
+	name := w.Engine + " " + w.Version + "'s source"
+	if err := in.download(ctx, url, name, archive, src.SHA256, st); err != nil {
+		return nil, err
+	}
+	in.progress(st, "unpacking %s", name)
+	if err := untarGz(archive, scratch); err != nil {
+		return nil, fmt.Errorf("unpacking %s: %w", name, err)
+	}
+	dst := filepath.Join(env, src.Dir)
+	if err := os.Rename(filepath.Join(scratch, src.Top), dst); err != nil {
+		return nil, fmt.Errorf("%s has no %s at its top: %w", name, src.Top, err)
+	}
+	if src.Requirements == "" {
+		return nil, nil
+	}
+	f, err := os.ReadFile(filepath.Join(dst, src.Requirements))
+	if err != nil {
+		return nil, fmt.Errorf("%s: %w", name, err)
+	}
+	return requirementsIn(string(f), b.IndexPackages)
+}
+
+// requirementsIn reads a requirements file's lines. Options (-r, -e, --index-url
+// and the like) are refused: they would fetch from somewhere other than PyPI,
+// or install what the lock never saw.
+func requirementsIn(text string, skip []string) ([]string, error) {
+	var out []string
+	for _, line := range strings.Split(text, "\n") {
+		line, _, _ = strings.Cut(line, "#")
+		line = strings.TrimSpace(line)
+		if line == "" {
+			continue
+		}
+		if strings.HasPrefix(line, "-") || strings.Contains(line, "://") || strings.Contains(line, " @ ") {
+			return nil, fmt.Errorf("the requirements name %q, which is not a package from PyPI", line)
+		}
+		name := strings.ToLower(line)
+		if i := strings.IndexAny(name, "<>=!~;[ "); i >= 0 {
+			name = name[:i]
+		}
+		if slices.Contains(skip, name) {
+			continue
+		}
+		out = append(out, line)
+	}
+	return out, nil
+}