From 8c47e8b92f0a18e36ee63f7e54c8efe48a2fbbff Mon Sep 17 00:00:00 2001
From: Palash Debnath <4178343+debpalash@users.noreply.github.com>
Date: Thu, 17 Sep 2026 12:16:09 +0530
Subject: [PATCH] fix: consolidate Argos coverage and reject silent script
 changes

---
 CHANGELOG.md                            | 4 ++++
 backend/services/translation_engines.py | 7 ++++++-
 docs/dubbing/translation-engines.md     | 2 ++
 tests/test_dub_translate.py             | 8 +++++++-
 4 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2c6df8b7..d49b8744 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -16,6 +16,10 @@ the frozen-backend fallback mirror it for their toolchains.
 
 - Handle missing Electron signing credentials and retry packaging fixes without moving release tags (#2157)
 
+### Fixed
+
+- Normalize Argos language aliases without silently changing Traditional Chinese to Simplified (#2143, #2152) — thanks @gyanu2507 and @rollroyces!
+
 ## [0.5.3] — 2026-09-17
 
 **Highlights**
diff --git a/backend/services/translation_engines.py b/backend/services/translation_engines.py
index 64704ae5..5b2b957d 100644
--- a/backend/services/translation_engines.py
+++ b/backend/services/translation_engines.py
@@ -40,7 +40,6 @@ _ARGOS_LANG_ALIASES = {
 _ARGOS_NAME_ALIASES = {
     "chinese": "zh",
     "chinese (simplified)": "zh",
-    "chinese (traditional)": "zh",
     "mandarin": "zh",
 }
 
@@ -325,6 +324,12 @@ def argos_lang_code(value: str) -> str:
     """
     raw = str(value or "").strip()
     key = raw.lower()
+    parts = key.replace("_", "-").split("-")
+    if key == "chinese (traditional)" or (
+        parts[0] in {"zh", "zho", "cmn"} and
+        any(part in {"hant", "tw", "hk", "mo"} for part in parts[1:])
+    ):
+        raise ValueError("Argos does not provide Traditional Chinese; choose NLLB for this script")
     named = _ARGOS_NAME_ALIASES.get(key)
     if named:
         return named
diff --git a/docs/dubbing/translation-engines.md b/docs/dubbing/translation-engines.md
index f1654ca5..3dba9a4d 100644
--- a/docs/dubbing/translation-engines.md
+++ b/docs/dubbing/translation-engines.md
@@ -234,3 +234,5 @@ panels instead so neither editor becomes unusably small.
   from-source checkout.
 - **Installed it but still "needs install"** — restart the backend so Python
   picks up the newly-installed module.
+
+Argos accepts Chinese/Simplified Chinese names, Mandarin aliases, and language tags such as `zh-CN`. Traditional Chinese requests (`zh-TW`, `zh-Hant`, and the display name) are rejected explicitly; select NLLB for Traditional Chinese rather than silently receiving a different script.
diff --git a/tests/test_dub_translate.py b/tests/test_dub_translate.py
index ec5fdb32..6133eb8a 100644
--- a/tests/test_dub_translate.py
+++ b/tests/test_dub_translate.py
@@ -22,7 +22,6 @@ def test_translate_codes_cover_popular_iso():
     # Human / display names from the dub UI's own label list.
     ("Chinese", "zh"),
     ("Chinese (Simplified)", "zh"),
-    ("Chinese (Traditional)", "zh"),
     ("Mandarin", "zh"),
     # Three-letter ISO 639-2 / bibliographic codes used by some asset pipelines.
     ("zho", "zh"),
@@ -826,3 +825,10 @@ async def test_openai_env_fallback_still_works(monkeypatch):
     resp = await dub_translate.dub_translate(req)
     assert resp["translated"][0]["text"] == "hola mundo"
     assert calls and calls[0]["model"] == "env-model"
+
+
+@pytest.mark.parametrize("raw", ["Chinese (Traditional)", "zh-TW", "zh-Hant", "cmn-Hant", "zho_Hant", "zh-HK", "zh-MO"])
+def test_argos_does_not_silently_change_chinese_script(raw):
+    from services.translation_engines import argos_lang_code
+    with pytest.raises(ValueError, match="Traditional Chinese.*NLLB"):
+        argos_lang_code(raw)