diff --git a/cmd/ninja/cmd/plugin.go b/cmd/ninja/cmd/plugin.go
index 9598784..048da1a 100644
--- a/cmd/ninja/cmd/plugin.go
+++ b/cmd/ninja/cmd/plugin.go
@@ -34,6 +34,7 @@ func newPluginCmd() *cobra.Command {
 		newPluginDeleteVersionCmd(),
 		newPluginBumpCmd(),
 		newPluginVersionCmd(),
+		newPluginTagsCmd(),
 	)
 	return c
 }
diff --git a/cmd/ninja/cmd/plugin_tags.go b/cmd/ninja/cmd/plugin_tags.go
new file mode 100644
index 0000000..bc84f08
--- /dev/null
+++ b/cmd/ninja/cmd/plugin_tags.go
@@ -0,0 +1,179 @@
+package cmd
+
+import (
+	"fmt"
+	"os"
+	"sort"
+	"strings"
+
+	"github.com/spf13/cobra"
+
+	core "git.dev.alexdunmow.com/block/core/plugin"
+	"git.dev.alexdunmow.com/block/core/cmd/ninja/internal/creds"
+	"git.dev.alexdunmow.com/block/core/cmd/ninja/internal/orchclient"
+)
+
+func newPluginTagsCmd() *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "tags",
+		Short: "Show current tags and popular tags from the registry",
+		RunE: func(c *cobra.Command, _ []string) error {
+			mod, err := readLocalMod()
+			if err != nil {
+				return err
+			}
+			if len(mod.Plugin.Tags) == 0 {
+				fmt.Println("Current tags: (none)")
+			} else {
+				fmt.Printf("Current tags: %s\n", strings.Join(mod.Plugin.Tags, ", "))
+			}
+
+			host, _ := c.Flags().GetString("host")
+			cr, err := creds.Load()
+			if err != nil {
+				return nil // not signed in is fine — silent best-effort
+			}
+			resolvedHost, hc, err := cr.Resolve(host)
+			if err != nil {
+				return nil
+			}
+			cli := orchclient.New(resolvedHost, hc.Token)
+			_ = cli
+
+			// TODO(tags): re-enable once core regenerates proto bindings to expose v1.ListTagsRequest (plan Task 12).
+			// resp, err := cli.Reg.ListTags(context.Background(), connect.NewRequest(&v1.ListTagsRequest{Kind: mod.Plugin.Kind, Limit: 20}))
+			// if err != nil {
+			// 	fmt.Println("(could not fetch popular tags — orchestrator unreachable)")
+			// 	return nil
+			// }
+			// if len(resp.Msg.Tags) == 0 {
+			// 	fmt.Println("Popular tags: (none yet)")
+			// 	return nil
+			// }
+			// parts := make([]string, len(resp.Msg.Tags))
+			// for i, t := range resp.Msg.Tags {
+			// 	parts[i] = fmt.Sprintf("%s (%d)", t.Tag, t.Count)
+			// }
+			// fmt.Printf("Popular: %s\n", strings.Join(parts, ", "))
+			fmt.Println("(popular tags unavailable — orchestrator bindings not yet regenerated)")
+			return nil
+		},
+	}
+
+	cmd.AddCommand(&cobra.Command{
+		Use:   "add <tag>...",
+		Short: "Add tags to the local plugin.mod (union with current)",
+		Args:  cobra.MinimumNArgs(1),
+		RunE:  func(_ *cobra.Command, args []string) error { return mutateTags("add", args) },
+	})
+	cmd.AddCommand(&cobra.Command{
+		Use:   "rm <tag>...",
+		Short: "Remove tags from the local plugin.mod",
+		Args:  cobra.MinimumNArgs(1),
+		RunE:  func(_ *cobra.Command, args []string) error { return mutateTags("rm", args) },
+	})
+	cmd.AddCommand(&cobra.Command{
+		Use:   "set <tag>...",
+		Short: "Replace all tags in the local plugin.mod",
+		Args:  cobra.MinimumNArgs(1),
+		RunE:  func(_ *cobra.Command, args []string) error { return mutateTags("set", args) },
+	})
+	cmd.AddCommand(&cobra.Command{
+		Use:   "clear",
+		Short: "Remove all tags from the local plugin.mod",
+		Args:  cobra.NoArgs,
+		RunE:  func(_ *cobra.Command, _ []string) error { return mutateTags("clear", nil) },
+	})
+
+	return cmd
+}
+
+// mutateTags reads plugin.mod, computes the new tag set, normalises, and writes
+// it back. Prints the before→after diff and a reminder to publish.
+func mutateTags(op string, args []string) error {
+	mod, err := readLocalMod()
+	if err != nil {
+		return err
+	}
+	before := append([]string(nil), mod.Plugin.Tags...)
+
+	var next []string
+	switch op {
+	case "add":
+		next = append(append([]string(nil), before...), args...)
+	case "rm":
+		drop := map[string]struct{}{}
+		for _, a := range args {
+			drop[strings.ToLower(strings.TrimSpace(a))] = struct{}{}
+		}
+		for _, t := range before {
+			if _, gone := drop[t]; !gone {
+				next = append(next, t)
+			}
+		}
+	case "set":
+		next = append([]string(nil), args...)
+	case "clear":
+		next = nil
+	default:
+		return fmt.Errorf("unknown tag op: %s", op)
+	}
+
+	normalised, err := core.NormalizeTags(next)
+	if err != nil {
+		return err
+	}
+
+	if err := writeLocalModTags(mod, normalised); err != nil {
+		return err
+	}
+
+	sortedBefore := append([]string(nil), before...)
+	sortedAfter := append([]string(nil), normalised...)
+	sort.Strings(sortedBefore)
+	sort.Strings(sortedAfter)
+	fmt.Printf("Tags: [%s] → [%s]\n", strings.Join(sortedBefore, ", "), strings.Join(sortedAfter, ", "))
+	if !equalStringSlices(sortedBefore, sortedAfter) {
+		fmt.Println("Run 'ninja plugin publish' to push to the registry.")
+	}
+	return nil
+}
+
+func readLocalMod() (*core.ModFile, error) {
+	b, err := os.ReadFile("plugin.mod")
+	if err != nil {
+		return nil, fmt.Errorf("read plugin.mod: %w", err)
+	}
+	mod, err := core.ParseModFull(b)
+	if err != nil {
+		return nil, fmt.Errorf("parse plugin.mod: %w", err)
+	}
+	return mod, nil
+}
+
+// writeLocalModTags rewrites plugin.mod with the new tag set, preserving all
+// other fields by reusing upsertPluginMod.
+func writeLocalModTags(mod *core.ModFile, tags []string) error {
+	return upsertPluginMod(
+		mod.Plugin.Scope,
+		mod.Plugin.Name,
+		mod.Plugin.DisplayName,
+		mod.Plugin.Description,
+		mod.Plugin.Kind,
+		mod.Plugin.Categories,
+		tags,
+		mod.Plugin.Private,
+	)
+}
+
+func equalStringSlices(a, b []string) bool {
+	if len(a) != len(b) {
+		return false
+	}
+	for i := range a {
+		if a[i] != b[i] {
+			return false
+		}
+	}
+	return true
+}