feat(api): normalize CLI list arguments

Co-Authored-By: Virgil <virgil@lethean.io>

cmd/api/cmd_args.go

@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: EUPL-1.2
+
+package api
+
+import "strings"
+
+// splitUniqueCSV trims and deduplicates a comma-separated list while
+// preserving the first occurrence of each value.
+func splitUniqueCSV(raw string) []string {
+	if raw == "" {
+		return nil
+	}
+
+	parts := strings.Split(raw, ",")
+	values := make([]string, 0, len(parts))
+	seen := make(map[string]struct{}, len(parts))
+
+	for _, part := range parts {
+		value := strings.TrimSpace(part)
+		if value == "" {
+			continue
+		}
+		if _, ok := seen[value]; ok {
+			continue
+		}
+		seen[value] = struct{}{}
+		values = append(values, value)
+	}
+
+	return values
+}

cmd/api/cmd_sdk.go

@@ -25,8 +25,9 @@ func addSDKCommand(parent *cli.Command) {
 	)
 
 	cmd := cli.NewCommand("sdk", "Generate client SDKs from OpenAPI spec", "", func(cmd *cli.Command, args []string) error {
-		if lang == "" {
-			return coreerr.E("sdk.Generate", "--lang is required. Supported: "+strings.Join(goapi.SupportedLanguages(), ", "), nil)
+		languages := splitUniqueCSV(lang)
+		if len(languages) == 0 {
+			return coreerr.E("sdk.Generate", "--lang is required and must include at least one non-empty language. Supported: "+strings.Join(goapi.SupportedLanguages(), ", "), nil)
 		}
 
 		// If no spec file provided, generate one to a temp file.
@@ -68,11 +69,7 @@ func addSDKCommand(parent *cli.Command) {
 		}
 
 		// Generate for each language.
-		for l := range strings.SplitSeq(lang, ",") {
-			l = strings.TrimSpace(l)
-			if l == "" {
-				continue
-			}
+		for _, l := range languages {
 			fmt.Fprintf(os.Stderr, "Generating %s SDK...\n", l)
 			if err := gen.Generate(context.Background(), l); err != nil {
 				return coreerr.E("sdk.Generate", "generate "+l, err)

cmd/api/cmd_spec.go

@@ -5,7 +5,6 @@ package api
 import (
 	"fmt"
 	"os"
-	"strings"
 
 	"forge.lthn.ai/core/cli/pkg/cli"
 
@@ -60,17 +59,5 @@ func addSpecCommand(parent *cli.Command) {
 }
 
 func parseServers(raw string) []string {
-	if raw == "" {
-		return nil
-	}
-
-	parts := strings.Split(raw, ",")
-	servers := make([]string, 0, len(parts))
-	for _, part := range parts {
-		if server := strings.TrimSpace(part); server != "" {
-			servers = append(servers, server)
-		}
-	}
-
-	return servers
+	return splitUniqueCSV(raw)
 }

cmd/api/cmd_test.go

@@ -99,7 +99,7 @@ func TestAPISpecCmd_Good_ServerFlagAddsServers(t *testing.T) {
 	AddAPICommands(root)
 
 	outputFile := t.TempDir() + "/spec.json"
-	root.SetArgs([]string{"api", "spec", "--server", "https://api.example.com,/", "--output", outputFile})
+	root.SetArgs([]string{"api", "spec", "--server", "https://api.example.com, /, https://api.example.com, ", "--output", outputFile})
 	root.SetErr(new(bytes.Buffer))
 
 	if err := root.Execute(); err != nil {
@@ -123,6 +123,27 @@ func TestAPISpecCmd_Good_ServerFlagAddsServers(t *testing.T) {
 	if len(servers) != 2 {
 		t.Fatalf("expected 2 servers, got %d", len(servers))
 	}
+	if servers[0].(map[string]any)["url"] != "https://api.example.com" {
+		t.Fatalf("expected first server to be https://api.example.com, got %v", servers[0])
+	}
+	if servers[1].(map[string]any)["url"] != "/" {
+		t.Fatalf("expected second server to be /, got %v", servers[1])
+	}
+}
+
+func TestAPISDKCmd_Bad_EmptyLanguages(t *testing.T) {
+	root := &cli.Command{Use: "root"}
+	AddAPICommands(root)
+
+	root.SetArgs([]string{"api", "sdk", "--lang", " , , "})
+	buf := new(bytes.Buffer)
+	root.SetOut(buf)
+	root.SetErr(buf)
+
+	err := root.Execute()
+	if err == nil {
+		t.Fatal("expected error when --lang only contains empty values")
+	}
 }
 
 func TestAPISDKCmd_Bad_NoLang(t *testing.T) {