feat(vendor): --exclude plus content-type selection (--types/--exclude-types)

vendor add gains --exclude a,b,c (all mode minus those ids) as the mirror
of --include, for taking the majority of a source while dropping a few
items. Mutual exclusion with --include is a hard error, unknown ids fail
naming the available ones (generalized checkIDEntries).

vendor add and vendor select gain --types (allow-list) and --exclude-types
(deny-list) over the four content types. The filter is stored as the
optional, v2-compatible Selection.exclude_types field and survives vendor
update: new upstream items of an excluded type never enter the work
repository (unlike id expansion, which would silently re-admit them).
--types/--exclude-types replace the filter on select, absent flags keep
it, and --mode all clears it along with include/exclude.

Also fixes materializeTree to create the staging directory for an empty
selection — previously select-to-zero failed at the staging rename.

internal/vendor/add.go

@@ -21,11 +21,14 @@ const externalDir = "external"
 
 // AddOptions parameterize vendor add.
 type AddOptions struct {
-	Name    string
-	URL     string
-	Ref     string
-	Include []string
-	Renames map[string]string
+	Name         string
+	URL          string
+	Ref          string
+	Include      []string
+	Exclude      []string
+	OnlyTypes    []string
+	ExcludeTypes []string
+	Renames      map[string]string
 }
 
 // Add vendors a new source into the work repository at workDir: it clones,
@@ -68,12 +71,29 @@ func Add(workDir string, opts AddOptions, stdout io.Writer) error {
 		return err
 	}
 
-	sel := lockfile.Selection{Mode: lockfile.ModeAll}
-	if len(opts.Include) > 0 {
-		sel = lockfile.Selection{Mode: lockfile.ModeInclude, Include: opts.Include}
-		if err := checkIncludeEntries(items, opts.Include, opts.Name); err != nil {
+	if len(opts.Include) > 0 && len(opts.Exclude) > 0 {
+		return fmt.Errorf("--include and --exclude cannot be combined (a v2 selection is either include mode or all mode minus excludes)")
+	}
+	excludeTypes, err := TypeFilter(opts.OnlyTypes, opts.ExcludeTypes)
+	if err != nil {
+		return err
+	}
+
+	sel := lockfile.Selection{Mode: lockfile.ModeAll, ExcludeTypes: excludeTypes}
+	switch {
+	case len(opts.Include) > 0:
+		sel = lockfile.Selection{Mode: lockfile.ModeInclude, Include: opts.Include, ExcludeTypes: excludeTypes}
+		if err := checkIDEntries(items, opts.Include, opts.Name, "include"); err != nil {
 			return err
 		}
+	case len(opts.Exclude) > 0:
+		sel.Exclude = opts.Exclude
+		if err := checkIDEntries(items, opts.Exclude, opts.Name, "exclude"); err != nil {
+			return err
+		}
+	}
+	if err := checkIncludeVsTypes(items, sel, opts.Name); err != nil {
+		return err
 	}
 
 	selected := applySelection(items, sel)
@@ -147,21 +167,96 @@ func discoveryFromTreeRoot(root string) lockfile.Discovery {
 	return d
 }
 
-func checkIncludeEntries(items []discovery.Item, include []string, name string) error {
+// checkIDEntries fails when any id is not available upstream (not discovered
+// or skipped) — typo protection for include and exclude lists alike.
+func checkIDEntries(items []discovery.Item, ids []string, name, flag string) error {
 	available := map[string]bool{}
 	for _, it := range items {
 		if !it.Skipped {
 			available[it.UpstreamID] = true
 		}
 	}
-	for _, want := range include {
+	for _, want := range ids {
 		if !available[want] {
-			return fmt.Errorf("source %q: include entry %q not found upstream (available: %s)", name, want, strings.Join(sortedKeys(available), ", "))
+			return fmt.Errorf("source %q: %s entry %q not found upstream (available: %s)", name, flag, want, strings.Join(sortedKeys(available), ", "))
 		}
 	}
 	return nil
 }
 
+// checkIncludeVsTypes fails when an include id belongs to a type excluded by
+// the type filter — silently dropping it would betray the explicit include.
+func checkIncludeVsTypes(items []discovery.Item, sel lockfile.Selection, name string) error {
+	if sel.Mode != lockfile.ModeInclude || len(sel.ExcludeTypes) == 0 {
+		return nil
+	}
+	excluded := map[string]bool{}
+	for _, t := range sel.ExcludeTypes {
+		excluded[t] = true
+	}
+	for _, it := range items {
+		if it.Skipped || !excluded[it.Type] {
+			continue
+		}
+		for _, id := range sel.Include {
+			if id == it.UpstreamID {
+				return fmt.Errorf("source %q: include entry %q belongs to type %s, which the type filter excludes", name, id, it.Type)
+			}
+		}
+	}
+	return nil
+}
+
+// TypeFilter translates --types (allow-list) and --exclude-types (deny-list)
+// into the canonical exclude_types list: the complement of the allow-list,
+// or the deny-list verbatim. Both empty means no filter (nil). A filter that
+// would exclude nothing normalizes to nil; a filter excluding everything is
+// returned as-is and fails later at the zero-selection guard.
+func TypeFilter(only, exclude []string) ([]string, error) {
+	if len(only) > 0 && len(exclude) > 0 {
+		return nil, fmt.Errorf("--types and --exclude-types cannot be combined")
+	}
+	if len(only) == 0 && len(exclude) == 0 {
+		return nil, nil
+	}
+	names := only
+	if len(names) == 0 {
+		names = exclude
+	}
+	valid := map[string]bool{}
+	for _, t := range lockfile.Types {
+		valid[t] = true
+	}
+	var unknown []string
+	for _, t := range names {
+		if !valid[t] {
+			unknown = append(unknown, t)
+		}
+	}
+	if len(unknown) > 0 {
+		return nil, fmt.Errorf("unknown content type(s) %s (valid: %s)", strings.Join(unknown, ", "), strings.Join(lockfile.Types, ", "))
+	}
+	if len(exclude) > 0 {
+		out := append([]string{}, exclude...)
+		sort.Strings(out)
+		return out, nil
+	}
+	allowed := map[string]bool{}
+	for _, t := range only {
+		allowed[t] = true
+	}
+	var out []string
+	for _, t := range lockfile.Types {
+		if !allowed[t] {
+			out = append(out, t)
+		}
+	}
+	if len(out) == 0 {
+		return nil, nil
+	}
+	return out, nil
+}
+
 func applySelection(items []discovery.Item, sel lockfile.Selection) []discovery.Item {
 	exclude := map[string]bool{}
 	for _, e := range sel.Exclude {
@@ -171,11 +266,18 @@ func applySelection(items []discovery.Item, sel lockfile.Selection) []discovery.
 	for _, i := range sel.Include {
 		include[i] = true
 	}
+	excludedTypes := map[string]bool{}
+	for _, t := range sel.ExcludeTypes {
+		excludedTypes[t] = true
+	}
 	var out []discovery.Item
 	for _, it := range items {
 		if it.Skipped {
 			continue
 		}
+		if excludedTypes[it.Type] {
+			continue
+		}
 		switch sel.Mode {
 		case lockfile.ModeInclude:
 			if include[it.UpstreamID] {
@@ -251,6 +353,9 @@ func reportAdd(w io.Writer, name string, src *lockfile.Source, discovered, selec
 	fmt.Fprintf(w, "  rev: %s\n", src.Rev)
 	fmt.Fprintf(w, "discovered %d items (%s)\n", real, counts(discovered))
 	fmt.Fprintf(w, "selected   %d items (%s)\n", len(selected), counts(selected))
+	if len(src.Selection.ExcludeTypes) > 0 {
+		fmt.Fprintf(w, "type filter: excluding %s\n", strings.Join(src.Selection.ExcludeTypes, ", "))
+	}
 	fmt.Fprintf(w, "materialized under %s/\n", filepath.Join(externalDir, name))
 	if len(src.Warnings) > 0 {
 		fmt.Fprintf(w, "warnings:\n")

internal/vendor/select.go

@@ -15,9 +15,11 @@ import (
 
 // SelectOptions parameterize vendor select.
 type SelectOptions struct {
-	Add     []string
-	Remove  []string
-	ModeAll bool
+	Add          []string
+	Remove       []string
+	ModeAll      bool
+	OnlyTypes    []string
+	ExcludeTypes []string
 }
 
 // Select changes what a vendored source contributes — without advancing the
@@ -60,6 +62,9 @@ func Select(workDir, name string, opts SelectOptions, stdout io.Writer) (*Change
 	if err := validateSelectIDs(items, src, opts, name); err != nil {
 		return nil, err
 	}
+	if err := checkIncludeVsTypes(items, newSel, name); err != nil {
+		return nil, err
+	}
 
 	selected := applySelection(items, newSel)
 	if err := checkCollisions(workDir, lf, name, selected, src.Renames); err != nil {
@@ -99,6 +104,9 @@ func Select(workDir, name string, opts SelectOptions, stdout io.Writer) (*Change
 	}
 
 	fmt.Fprintf(stdout, "source %s: selection updated at pinned rev %s (mode %s)\n", name, short(src.Rev), newSel.Mode)
+	if len(newSel.ExcludeTypes) > 0 {
+		fmt.Fprintf(stdout, "  type filter: excluding %s\n", strings.Join(newSel.ExcludeTypes, ", "))
+	}
 	printChangeReport(stdout, report)
 	return report, nil
 }
@@ -106,30 +114,43 @@ func Select(workDir, name string, opts SelectOptions, stdout io.Writer) (*Change
 // planSelection derives the new selection from the flags — pure, before any
 // upstream contact: --mode all resets to everything; include mode grows and
 // shrinks the include list; all mode --remove moves ids onto the exclude
-// list.
+// list. --types/--exclude-types replace the type filter (absent flags keep
+// it; --mode all clears it along with include/exclude).
 func planSelection(src *lockfile.Source, opts SelectOptions, name string) (lockfile.Selection, error) {
+	typeFilter, err := TypeFilter(opts.OnlyTypes, opts.ExcludeTypes)
+	if err != nil {
+		return lockfile.Selection{}, err
+	}
 	if opts.ModeAll {
-		if len(opts.Add) > 0 || len(opts.Remove) > 0 {
-			return lockfile.Selection{}, fmt.Errorf("--mode all cannot be combined with --add or --remove")
+		if len(opts.Add) > 0 || len(opts.Remove) > 0 || typeFilter != nil {
+			return lockfile.Selection{}, fmt.Errorf("--mode all cannot be combined with --add, --remove, --types or --exclude-types")
 		}
 		return lockfile.Selection{Mode: lockfile.ModeAll}, nil
 	}
-	if len(opts.Add) == 0 && len(opts.Remove) == 0 {
-		return lockfile.Selection{}, fmt.Errorf("nothing to do: pass --add <ids>, --remove <ids> or --mode all")
+	if len(opts.Add) == 0 && len(opts.Remove) == 0 && typeFilter == nil {
+		return lockfile.Selection{}, fmt.Errorf("nothing to do: pass --add <ids>, --remove <ids>, --types/--exclude-types or --mode all")
 	}
+	var newSel lockfile.Selection
 	if src.Selection.Mode == lockfile.ModeAll {
 		if len(opts.Add) > 0 {
 			return lockfile.Selection{}, fmt.Errorf("source %q: everything is already selected in all mode; use --remove <ids> to exclude items", name)
 		}
-		return lockfile.Selection{
+		newSel = lockfile.Selection{
 			Mode:    lockfile.ModeAll,
 			Exclude: unionIDs(src.Selection.Exclude, opts.Remove),
-		}, nil
+		}
+	} else {
+		newSel = lockfile.Selection{
+			Mode:    lockfile.ModeInclude,
+			Include: unionIDs(minusIDs(src.Selection.Include, opts.Remove), opts.Add),
+		}
 	}
-	return lockfile.Selection{
-		Mode:    lockfile.ModeInclude,
-		Include: unionIDs(minusIDs(src.Selection.Include, opts.Remove), opts.Add),
-	}, nil
+	if typeFilter != nil {
+		newSel.ExcludeTypes = typeFilter
+	} else {
+		newSel.ExcludeTypes = src.Selection.ExcludeTypes
+	}
+	return newSel, nil
 }
 
 // validateSelectIDs checks flag ids against the pinned upstream (and, for
@@ -137,7 +158,7 @@ func planSelection(src *lockfile.Source, opts SelectOptions, name string) (lockf
 // before anything is mutated.
 func validateSelectIDs(items []discovery.Item, src *lockfile.Source, opts SelectOptions, name string) error {
 	if len(opts.Add) > 0 {
-		if err := checkIncludeEntries(items, opts.Add, name); err != nil {
+		if err := checkIDEntries(items, opts.Add, name, "include"); err != nil {
 			return fmt.Errorf("--add: %w", err)
 		}
 	}
@@ -153,7 +174,7 @@ func validateSelectIDs(items []discovery.Item, src *lockfile.Source, opts Select
 		}
 	}
 	if len(opts.Remove) > 0 && src.Selection.Mode == lockfile.ModeAll {
-		if err := checkIncludeEntries(items, opts.Remove, name); err != nil {
+		if err := checkIDEntries(items, opts.Remove, name, "exclude"); err != nil {
 			return fmt.Errorf("--remove: %w", err)
 		}
 	}

internal/vendor/update.go

@@ -197,7 +197,7 @@ func computeUpdate(workDir string, lf *lockfile.Lockfile, name string, withColli
 	}
 
 	if src.Selection.Mode == lockfile.ModeInclude {
-		if err := checkIncludeEntries(items, src.Selection.Include, name); err != nil {
+		if err := checkIDEntries(items, src.Selection.Include, name, "include"); err != nil {
 			return nil, err
 		}
 	}
@@ -250,6 +250,11 @@ func cleanupStaleStaging(workDir string) {
 }
 
 func materializeTree(tree discovery.Tree, selected []discovery.Item, renames map[string]string, dst string) error {
+	// Create dst even for an empty selection: the caller swaps it in with a
+	// rename, which fails when nothing materialized the directory.
+	if err := os.MkdirAll(dst, 0o755); err != nil {
+		return err
+	}
 	for _, it := range selected {
 		dep := deployedName(it.UpstreamID, renames)
 		base := filepath.Join(dst, it.Type)