feat(core): improve xcstrings translate workflow

Author: WendellXY

langcodec-cli/README.md

@@ -107,12 +107,17 @@ Behavior:
 - writes generated values as `needs_review`
 - skips plural entries in v1
 - writes in-place by default and supports `--dry-run`
+- performs output preflight validation before sending model requests
+- shows live progress in interactive terminals and prints translated result lines after completion
+- supports comma-separated `--target-lang` values for multi-language outputs such as `.xcstrings`, `.csv`, and `.tsv`
+- supports `translate.source` and `translate.sources` in `langcodec.toml`, so `langcodec translate` can run with no path flags
 - supports translate defaults from `langcodec.toml`
 
 Example `langcodec.toml`:
 
 ```toml
 [translate]
+source = "locales/Localizable.xcstrings"
 provider = "openai"
 model = "gpt-4.1-mini"
 source_lang = "en"
@@ -121,10 +126,28 @@ concurrency = 4
 status = ["new", "stale"]
 ```
 
+For multi-language outputs, `target_lang` may also be a comma-separated string such as `"fr,de,ja"`.
+
+For parallel config-driven runs, use:
+
+```toml
+[translate]
+sources = [
+  "features/auth/Localizable.xcstrings",
+  "features/profile/Localizable.xcstrings",
+]
+provider = "openai"
+model = "gpt-4.1-mini"
+source_lang = "en"
+target_lang = "fr,de"
+```
+
 Config notes:
 
 - save the file as `langcodec.toml` in your project root, or pass `--config /absolute/path/to/langcodec.toml`
 - config discovery walks upward from the current directory until it finds `langcodec.toml`
+- `translate.source`, `translate.sources`, `translate.target`, and `translate.output` are resolved relative to the `langcodec.toml` file
+- `translate.sources` fans out into parallel translate runs; it cannot be combined with a single shared `target` or `output`
 - CLI flags still override config values
 
 Provider/auth notes:

langcodec-cli/src/config.rs

@@ -9,6 +9,10 @@ pub struct CliConfig {
 
 #[derive(Debug, Clone, Default, Deserialize)]
 pub struct TranslateConfig {
+    pub source: Option<String>,
+    pub sources: Option<Vec<String>>,
+    pub target: Option<String>,
+    pub output: Option<String>,
     pub provider: Option<String>,
     pub model: Option<String>,
     pub source_lang: Option<String>,
@@ -28,7 +32,10 @@ pub fn load_config(explicit_path: Option<&str>) -> Result<Option<LoadedConfig>,
         Some(path) => {
             let resolved = PathBuf::from(path);
             if !resolved.exists() {
-                return Err(format!("Config file does not exist: {}", resolved.display()));
+                return Err(format!(
+                    "Config file does not exist: {}",
+                    resolved.display()
+                ));
             }
             resolved
         }

langcodec-cli/src/lib.rs

@@ -3,11 +3,11 @@
 pub mod config;
 pub mod formats;
 pub mod merge;
-pub mod translate;
 pub mod transformers;
+pub mod translate;
 pub mod validation;
 
 pub use formats::{CustomFormat, parse_custom_format};
 pub use langcodec::Codec;
-pub use translate::{TranslateOptions, run_translate_command};
 pub use transformers::custom_format_to_resource;
+pub use translate::{TranslateOptions, run_translate_command};

langcodec-cli/src/main.rs

@@ -9,8 +9,8 @@ mod normalize;
 mod path_glob;
 mod stats;
 mod sync;
-mod translate;
 mod transformers;
+mod translate;
 mod validation;
 mod view;
 
@@ -259,9 +259,9 @@ enum Commands {
 
     /// Translate source entries into a target language using Mentra-backed providers.
     Translate {
-        /// Source localization file
+        /// Source localization file. Required unless configured in `langcodec.toml`.
         #[arg(short = 's', long)]
-        source: String,
+        source: Option<String>,
 
         /// Optional target localization file. If omitted, translates in-place within multi-language files.
         #[arg(short = 't', long)]
@@ -275,9 +275,9 @@ enum Commands {
         #[arg(long)]
         source_lang: Option<String>,
 
-        /// Target language code.
-        #[arg(long)]
-        target_lang: Option<String>,
+        /// Target language code(s). Comma-separated values are supported for multi-language outputs.
+        #[arg(long, value_name = "LANG", value_delimiter = ',')]
+        target_lang: Vec<String>,
 
         /// Filter target entries by status before translating (default: new,stale)
         #[arg(long)]
@@ -710,7 +710,10 @@ fn main() {
             config,
             dry_run,
         } => {
-            let mut context = ValidationContext::new().with_input_file(source.clone());
+            let mut context = ValidationContext::new();
+            if let Some(source_path) = &source {
+                context = context.with_input_file(source_path.clone());
+            }
             if let Some(target_path) = &target
                 && std::path::Path::new(target_path).exists()
             {
@@ -728,19 +731,19 @@ fn main() {
                 eprintln!("❌ Validation failed: {}", e);
                 std::process::exit(1);
             }
-            if let Some(lang_code) = &target_lang
-                && let Err(e) = validate_language_code(lang_code)
-            {
-                eprintln!("❌ Validation failed: {}", e);
-                std::process::exit(1);
+            for lang_code in &target_lang {
+                if let Err(e) = validate_language_code(lang_code) {
+                    eprintln!("❌ Validation failed: {}", e);
+                    std::process::exit(1);
+                }
             }
 
             if let Err(e) = run_translate_command(TranslateOptions {
                 source,
                 target,
                 output,
                 source_lang,
-                target_lang,
+                target_langs: target_lang,
                 status,
                 provider,
                 model,