fix(skills): use --registry flag value as registry name

The --registry flag value was previously ignored and only used as a
switch. Now the flag value is properly used as the registry name.

Fixes #1104

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>

cmd/picoclaw/internal/skills/install.go

@@ -21,8 +21,8 @@ picoclaw skills install --registry clawhub github
 `,
 		Args: func(cmd *cobra.Command, args []string) error {
 			if registry != "" {
-				if len(args) != 2 {
-					return fmt.Errorf("when --registry is set, exactly 2 arguments are required: <name> <slug>")
+				if len(args) != 1 {
+					return fmt.Errorf("when --registry is set, exactly 1 argument is required: <slug>")
 				}
 				return nil
 			}
@@ -45,7 +45,7 @@ picoclaw skills install --registry clawhub github
 					return err
 				}
 
-				return skillsInstallFromRegistry(cfg, args[0], args[1])
+				return skillsInstallFromRegistry(cfg, registry, args[0])
 			}
 
 			return skillsInstallCmd(installer, args[0])

cmd/picoclaw/internal/skills/install_test.go

@@ -26,3 +26,72 @@ func TestNewInstallSubcommand(t *testing.T) {
 
 	assert.Len(t, cmd.Aliases, 0)
 }
+
+func TestInstallCommandArgs(t *testing.T) {
+	tests := []struct {
+		name        string
+		args        []string
+		registry    string
+		expectError bool
+		errorMsg    string
+	}{
+		{
+			name:        "no registry, one arg",
+			args:        []string{"sipeed/picoclaw-skills/weather"},
+			registry:    "",
+			expectError: false,
+		},
+		{
+			name:        "no registry, no args",
+			args:        []string{},
+			registry:    "",
+			expectError: true,
+			errorMsg:    "exactly 1 argument is required: <github>",
+		},
+		{
+			name:        "no registry, too many args",
+			args:        []string{"arg1", "arg2"},
+			registry:    "",
+			expectError: true,
+			errorMsg:    "exactly 1 argument is required: <github>",
+		},
+		{
+			name:        "with registry, one arg",
+			args:        []string{"weather-skill"},
+			registry:    "clawhub",
+			expectError: false,
+		},
+		{
+			name:        "with registry, no args",
+			args:        []string{},
+			registry:    "clawhub",
+			expectError: true,
+			errorMsg:    "when --registry is set, exactly 1 argument is required: <slug>",
+		},
+		{
+			name:        "with registry, too many args",
+			args:        []string{"arg1", "arg2"},
+			registry:    "clawhub",
+			expectError: true,
+			errorMsg:    "when --registry is set, exactly 1 argument is required: <slug>",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			cmd := newInstallCommand(nil)
+
+			if tt.registry != "" {
+				require.NoError(t, cmd.Flags().Set("registry", tt.registry))
+			}
+
+			err := cmd.Args(cmd, tt.args)
+			if tt.expectError {
+				require.Error(t, err)
+				assert.Equal(t, tt.errorMsg, err.Error())
+			} else {
+				require.NoError(t, err)
+			}
+		})
+	}
+}