diff --git a/services/providers/deepseek_provider.py b/services/providers/deepseek_provider.py
index 1f13554..5d9e118 100644
--- a/services/providers/deepseek_provider.py
+++ b/services/providers/deepseek_provider.py
@@ -44,6 +44,24 @@ def _get_language_name(code: str) -> str:
 
     return language_name(code)
 
+
+def _build_system_prompt(
+    source_lang: str, target_lang: str, custom_prompt: Optional[str] = None
+) -> str:
+    """Build system prompt for translation.
+
+    The base translation instructions are ALWAYS present — a custom prompt
+    (glossary, tone, context) is appended as additional directives, never a
+    replacement. Same contract as the OpenAI provider.
+    """
+    base = DEFAULT_TRANSLATION_PROMPT.format(
+        source_lang=source_lang, target_lang=target_lang
+    )
+    if custom_prompt and custom_prompt.strip():
+        return f"{base}\n\nADDITIONAL CONTEXT AND INSTRUCTIONS:\n{custom_prompt.strip()}"
+    return base
+
+
 class DeepSeekProviderError(Exception):
     def __init__(self, code: str, message: str, details: Optional[Dict[str, Any]] = None):
         self.code = code
@@ -155,19 +173,11 @@ class DeepSeekTranslationProvider(TranslationProvider):
         source_lang_name = _get_language_name(source_language)
         target_lang_name = _get_language_name(target_language)
         custom_prompt = request.metadata.get("custom_prompt") if request.metadata else None
-        _base_prompt = DEFAULT_TRANSLATION_PROMPT.format(
-            source_lang=source_lang_name, target_lang=target_lang_name
-        )
         # Base translation instructions always present; the custom prompt
         # (glossary/tone/context) is appended, never a replacement.
-        if custom_prompt and custom_prompt.strip():
-            system_prompt = (
-                _base_prompt
-                + "\n\nADDITIONAL CONTEXT AND INSTRUCTIONS:\n"
-                + custom_prompt.strip()
-            )
-        else:
-            system_prompt = _base_prompt
+        system_prompt = _build_system_prompt(
+            source_lang_name, target_lang_name, custom_prompt
+        )
 
         last_error = None
         for attempt in range(self._max_retries + 1):
@@ -196,7 +206,120 @@ class DeepSeekTranslationProvider(TranslationProvider):
             error=last_error.message if last_error else "Unknown error",
             error_code=last_error.code if last_error else DEEPSEEK_SERVICE_ERROR)
 
-    def translate_batch(self, requests: List[TranslationRequest]) -> List[TranslationResponse]:
+    def _make_batch_api_request(
+        self, texts: List[str], system_prompt: str
+    ) -> Optional[List[str]]:
+        """Translate a whole chunk in ONE request via a numbered JSON list.
+
+        The user message is a JSON array; the model must answer with a JSON
+        array of the same length. Returns None when the answer cannot be
+        parsed confidently — callers then fall back to per-item calls
+        (correctness over latency). Mirrors the OpenAI provider batch mode.
+        """
+        import json as _json
+
+        numbered = _json.dumps(
+            [{"id": i, "text": t} for i, t in enumerate(texts)],
+            ensure_ascii=False,
+        )
+        batch_system = (
+            system_prompt
+            + "\n\nBATCH MODE: the user message is a JSON array of items with "
+            "unique ids. Answer with ONLY a JSON array of objects "
+            '[{"id": <same id>, "translation": "<translated text>"}], same '
+            "length and same ids, in the same order. Translate every item; "
+            "keep ids unchanged; no comments, no markdown fence."
+        )
+
+        try:
+            content, _usage = self._make_api_request(numbered, batch_system)
+            raw = content.strip()
+            # Strip an optional markdown fence
+            if raw.startswith("```"):
+                raw = raw.strip("`")
+                if raw.lower().startswith("json"):
+                    raw = raw[4:]
+                raw = raw.strip()
+            parsed = _json.loads(raw)
+            if not isinstance(parsed, list) or len(parsed) != len(texts):
+                return None
+            out: List[str] = [""] * len(texts)
+            for item in parsed:
+                if not isinstance(item, dict):
+                    return None
+                idx = item.get("id")
+                translation = item.get("translation")
+                if not isinstance(idx, int) or not 0 <= idx < len(texts):
+                    return None
+                if not isinstance(translation, str) or not translation.strip():
+                    return None
+                out[idx] = translation.strip()
+            return out
+        except DeepSeekProviderError:
+            raise
+        except Exception:
+            return None
+
+    def translate_batch(
+        self, requests: List[TranslationRequest]
+    ) -> List[TranslationResponse]:
+        """
+        Translate multiple texts.
+
+        Chunks arrive from the translators as ~15 texts. When every request
+        shares the same language pair and metadata, they are sent in ONE
+        call (numbered JSON list — ~15x fewer requests, better contextual
+        consistency across neighbouring segments). Any parse/API doubt falls
+        back to the per-item path so a batch failure never corrupts output.
+        """
+        if not requests:
+            return []
+
+        same_pair = len({(r.source_language, r.target_language) for r in requests}) == 1
+        same_meta = len(
+            {tuple(sorted((r.metadata or {}).items())) for r in requests}
+        ) == 1
+
+        if same_pair and same_meta and len(requests) > 1:
+            try:
+                source_lang_name = _get_language_name(
+                    requests[0].source_language or "auto"
+                ) or "the source language (auto-detect)"
+                target_lang_name = _get_language_name(requests[0].target_language)
+                custom_prompt = None
+                if requests[0].metadata:
+                    custom_prompt = requests[0].metadata.get("custom_prompt")
+                system_prompt = _build_system_prompt(
+                    source_lang_name, target_lang_name, custom_prompt
+                )
+                texts = [r.text for r in requests]
+                translations = self._make_batch_api_request(texts, system_prompt)
+                if translations is not None:
+                    logger.info(
+                        "deepseek_batch_translation_success",
+                        items=len(requests),
+                        model=self._model,
+                    )
+                    return [
+                        TranslationResponse(
+                            translated_text=t,
+                            provider_name=self._provider_name,
+                            from_cache=False,
+                        )
+                        for t in translations
+                    ]
+                logger.warning(
+                    "deepseek_batch_translation_fallback",
+                    reason="unparseable_response",
+                    items=len(requests),
+                )
+            except Exception as e:
+                logger.warning(
+                    "deepseek_batch_translation_fallback",
+                    reason=type(e).__name__,
+                    items=len(requests),
+                )
+
         return [self.translate_text(req) for req in requests]
 
     def health_check(self) -> ProviderHealthStatus:
diff --git a/services/providers/minimax_provider.py b/services/providers/minimax_provider.py
index 7e36e98..a548ed1 100644
--- a/services/providers/minimax_provider.py
+++ b/services/providers/minimax_provider.py
@@ -46,6 +46,24 @@ def _get_language_name(code: str) -> str:
 
     return language_name(code)
 
+
+def _build_system_prompt(
+    source_lang: str, target_lang: str, custom_prompt: Optional[str] = None
+) -> str:
+    """Build system prompt for translation.
+
+    The base translation instructions are ALWAYS present — a custom prompt
+    (glossary, tone, context) is appended as additional directives, never a
+    replacement. Same contract as the OpenAI provider.
+    """
+    base = DEFAULT_TRANSLATION_PROMPT.format(
+        source_lang=source_lang, target_lang=target_lang
+    )
+    if custom_prompt and custom_prompt.strip():
+        return f"{base}\n\nADDITIONAL CONTEXT AND INSTRUCTIONS:\n{custom_prompt.strip()}"
+    return base
+
+
 class MinimaxProviderError(Exception):
     def __init__(self, code: str, message: str, details: Optional[Dict[str, Any]] = None):
         self.code = code
@@ -172,19 +190,11 @@ class MinimaxTranslationProvider(TranslationProvider):
         source_lang_name = _get_language_name(source_language)
         target_lang_name = _get_language_name(target_language)
         custom_prompt = request.metadata.get("custom_prompt") if request.metadata else None
-        _base_prompt = DEFAULT_TRANSLATION_PROMPT.format(
-            source_lang=source_lang_name, target_lang=target_lang_name
-        )
         # Base translation instructions always present; the custom prompt
         # (glossary/tone/context) is appended, never a replacement.
-        if custom_prompt and custom_prompt.strip():
-            system_prompt = (
-                _base_prompt
-                + "\n\nADDITIONAL CONTEXT AND INSTRUCTIONS:\n"
-                + custom_prompt.strip()
-            )
-        else:
-            system_prompt = _base_prompt
+        system_prompt = _build_system_prompt(
+            source_lang_name, target_lang_name, custom_prompt
+        )
 
         last_error = None
         for attempt in range(self._max_retries + 1):
@@ -213,7 +223,120 @@ class MinimaxTranslationProvider(TranslationProvider):
             error=last_error.message if last_error else "Unknown error",
             error_code=last_error.code if last_error else MINIMAX_SERVICE_ERROR)
 
-    def translate_batch(self, requests: List[TranslationRequest]) -> List[TranslationResponse]:
+    def _make_batch_api_request(
+        self, texts: List[str], system_prompt: str
+    ) -> Optional[List[str]]:
+        """Translate a whole chunk in ONE request via a numbered JSON list.
+
+        The user message is a JSON array; the model must answer with a JSON
+        array of the same length. Returns None when the answer cannot be
+        parsed confidently — callers then fall back to per-item calls
+        (correctness over latency). Mirrors the OpenAI provider batch mode.
+        """
+        import json as _json
+
+        numbered = _json.dumps(
+            [{"id": i, "text": t} for i, t in enumerate(texts)],
+            ensure_ascii=False,
+        )
+        batch_system = (
+            system_prompt
+            + "\n\nBATCH MODE: the user message is a JSON array of items with "
+            "unique ids. Answer with ONLY a JSON array of objects "
+            '[{"id": <same id>, "translation": "<translated text>"}], same '
+            "length and same ids, in the same order. Translate every item; "
+            "keep ids unchanged; no comments, no markdown fence."
+        )
+
+        try:
+            content, _usage = self._make_api_request(numbered, batch_system)
+            raw = content.strip()
+            # Strip an optional markdown fence
+            if raw.startswith("```"):
+                raw = raw.strip("`")
+                if raw.lower().startswith("json"):
+                    raw = raw[4:]
+                raw = raw.strip()
+            parsed = _json.loads(raw)
+            if not isinstance(parsed, list) or len(parsed) != len(texts):
+                return None
+            out: List[str] = [""] * len(texts)
+            for item in parsed:
+                if not isinstance(item, dict):
+                    return None
+                idx = item.get("id")
+                translation = item.get("translation")
+                if not isinstance(idx, int) or not 0 <= idx < len(texts):
+                    return None
+                if not isinstance(translation, str) or not translation.strip():
+                    return None
+                out[idx] = translation.strip()
+            return out
+        except MinimaxProviderError:
+            raise
+        except Exception:
+            return None
+
+    def translate_batch(
+        self, requests: List[TranslationRequest]
+    ) -> List[TranslationResponse]:
+        """
+        Translate multiple texts.
+
+        Chunks arrive from the translators as ~15 texts. When every request
+        shares the same language pair and metadata, they are sent in ONE
+        call (numbered JSON list — ~15x fewer requests, better contextual
+        consistency across neighbouring segments). Any parse/API doubt falls
+        back to the per-item path so a batch failure never corrupts output.
+        """
+        if not requests:
+            return []
+
+        same_pair = len({(r.source_language, r.target_language) for r in requests}) == 1
+        same_meta = len(
+            {tuple(sorted((r.metadata or {}).items())) for r in requests}
+        ) == 1
+
+        if same_pair and same_meta and len(requests) > 1:
+            try:
+                source_lang_name = _get_language_name(
+                    requests[0].source_language or "auto"
+                ) or "the source language (auto-detect)"
+                target_lang_name = _get_language_name(requests[0].target_language)
+                custom_prompt = None
+                if requests[0].metadata:
+                    custom_prompt = requests[0].metadata.get("custom_prompt")
+                system_prompt = _build_system_prompt(
+                    source_lang_name, target_lang_name, custom_prompt
+                )
+                texts = [r.text for r in requests]
+                translations = self._make_batch_api_request(texts, system_prompt)
+                if translations is not None:
+                    logger.info(
+                        "minimax_batch_translation_success",
+                        items=len(requests),
+                        model=self._model,
+                    )
+                    return [
+                        TranslationResponse(
+                            translated_text=t,
+                            provider_name=self._provider_name,
+                            from_cache=False,
+                        )
+                        for t in translations
+                    ]
+                logger.warning(
+                    "minimax_batch_translation_fallback",
+                    reason="unparseable_response",
+                    items=len(requests),
+                )
+            except Exception as e:
+                logger.warning(
+                    "minimax_batch_translation_fallback",
+                    reason=type(e).__name__,
+                    items=len(requests),
+                )
+
         return [self.translate_text(req) for req in requests]
 
     def health_check(self) -> ProviderHealthStatus:
diff --git a/tests/test_providers/test_deepseek_provider.py b/tests/test_providers/test_deepseek_provider.py
new file mode 100644
index 0000000..2d749bd
--- /dev/null
+++ b/tests/test_providers/test_deepseek_provider.py
@@ -0,0 +1,312 @@
+"""
+Tests for the DeepSeekTranslationProvider.
+
+Covers:
+- defaults (public endpoint ``api.deepseek.com/v1``, model ``deepseek-chat``)
+- translation success, 401/429 handling, empty-text short-circuit
+
+Batch mode (ported from the OpenAI provider):
+- same language pair + metadata chunk → ONE numbered-JSON request for all texts
+- unparseable/failed batch answer → per-item fallback, every text still translated
+- mixed metadata or a single text → no batch (individual requests)
+"""
+
+import json
+
+import pytest
+from unittest.mock import patch, MagicMock
+
+from services.providers.deepseek_provider import (
+    DeepSeekTranslationProvider,
+    DeepSeekProviderError,
+    DEEPSEEK_RATE_LIMITED,
+    DEEPSEEK_INVALID_KEY,
+    DEEPSEEK_TIMEOUT,
+    DEEPSEEK_SERVICE_ERROR,
+)
+from services.providers.schemas import TranslationRequest
+
+
+class TestDeepSeekProviderConfig:
+    """Defaults must point at the real public endpoint."""
+
+    def test_default_base_url_is_public_host(self):
+        provider = DeepSeekTranslationProvider(api_key="k", max_retries=0)
+        assert provider._base_url == "https://api.deepseek.com/v1"
+
+    def test_default_model_is_deepseek_chat(self):
+        provider = DeepSeekTranslationProvider(api_key="k", max_retries=0)
+        assert provider._model == "deepseek-chat"
+
+    def test_custom_base_url_respected(self):
+        provider = DeepSeekTranslationProvider(
+            api_key="k", base_url="https://proxy.example.com/v1", max_retries=0
+        )
+        assert provider._base_url == "https://proxy.example.com/v1"
+
+    def test_get_name(self):
+        provider = DeepSeekTranslationProvider(api_key="k", max_retries=0)
+        assert provider.get_name() == "deepseek"
+
+    def test_empty_api_key_raises(self):
+        with pytest.raises(ValueError, match="API key cannot be empty"):
+            DeepSeekTranslationProvider(api_key="   ")
+
+
+class TestDeepSeekTranslateText:
+    @pytest.fixture
+    def provider(self):
+        return DeepSeekTranslationProvider(api_key="k", max_retries=0)
+
+    def _mock_post(self, payload, status_code=200):
+        mock_response = MagicMock()
+        mock_response.status_code = status_code
+        mock_response.json.return_value = payload
+        mock_response.text = ""
+        return mock_response
+
+    @patch("requests.post")
+    def test_success(self, mock_post, provider):
+        mock_post.return_value = self._mock_post(
+            {"choices": [{"message": {"content": "Bonjour"}}], "usage": {}}
+        )
+        resp = provider.translate_text(TranslationRequest(text="Hello", target_language="fr"))
+        assert resp.translated_text == "Bonjour"
+        assert resp.provider_name == "deepseek"
+        assert mock_post.call_args[0][0] == "https://api.deepseek.com/v1/chat/completions"
+
+    def test_empty_text_short_circuits(self, provider):
+        resp = provider.translate_text(TranslationRequest(text="", target_language="fr"))
+        assert resp.translated_text == ""
+
+    @patch("requests.post")
+    def test_invalid_key_returns_error(self, mock_post, provider):
+        mock_post.return_value = self._mock_post({"error": "bad key"}, status_code=401)
+        resp = provider.translate_text(TranslationRequest(text="Hello", target_language="fr"))
+        assert resp.error_code == DEEPSEEK_INVALID_KEY
+        # Original text returned on failure.
+        assert resp.translated_text == "Hello"
+
+    @patch("time.sleep")
+    @patch("requests.post")
+    def test_rate_limit_then_success(self, mock_post, mock_sleep):
+        provider = DeepSeekTranslationProvider(api_key="k", max_retries=2, retry_delay=0.01)
+        mock_post.side_effect = [
+            self._mock_post({"error": "slow down"}, status_code=429),
+            self._mock_post({"choices": [{"message": {"content": "Hola"}}], "usage": {}}),
+        ]
+        resp = provider.translate_text(TranslationRequest(text="Hello", target_language="es"))
+        assert resp.translated_text == "Hola"
+        assert mock_sleep.called  # backoff happened
+
+    @patch("requests.post")
+    def test_service_error_when_empty_choices(self, mock_post, provider):
+        mock_post.return_value = self._mock_post({"choices": []})
+        resp = provider.translate_text(TranslationRequest(text="Hello", target_language="fr"))
+        assert resp.error_code == DEEPSEEK_SERVICE_ERROR
+
+
+class TestDeepSeekBatchTranslation:
+    """Batch mode: one numbered-JSON request per same pair/metadata chunk."""
+
+    @pytest.fixture
+    def provider(self):
+        return DeepSeekTranslationProvider(api_key="k", max_retries=0)
+
+    def _mock_post(self, payload, status_code=200):
+        mock_response = MagicMock()
+        mock_response.status_code = status_code
+        mock_response.json.return_value = payload
+        mock_response.text = ""
+        return mock_response
+
+    def _batch_response(self, translations):
+        """Mock a 200 response whose content is a numbered JSON array."""
+        content = json.dumps(
+            [{"id": i, "translation": t} for i, t in enumerate(translations)]
+        )
+        return self._mock_post({"choices": [{"message": {"content": content}}], "usage": {}})
+
+    @patch("requests.post")
+    def test_batch_of_three_uses_single_request(self, mock_post, provider):
+        mock_post.return_value = self._batch_response(["Bonjour", "Au revoir", "Merci"])
+        requests = [
+            TranslationRequest(text="Hello", target_language="fr"),
+            TranslationRequest(text="Goodbye", target_language="fr"),
+            TranslationRequest(text="Thank you", target_language="fr"),
+        ]
+
+        responses = provider.translate_batch(requests)
+
+        assert mock_post.call_count == 1
+        assert [r.translated_text for r in responses] == ["Bonjour", "Au revoir", "Merci"]
+        assert all(r.provider_name == "deepseek" for r in responses)
+        assert all(r.error is None for r in responses)
+        assert mock_post.call_args[0][0] == "https://api.deepseek.com/v1/chat/completions"
+
+    @patch("requests.post")
+    def test_batch_request_payload_is_numbered_json_with_instructions(self, mock_post, provider):
+        mock_post.return_value = self._batch_response(["Bonjour", "Au revoir"])
+        requests = [
+            TranslationRequest(
+                text="Hello",
+                target_language="fr",
+                source_language="en",
+                metadata={"custom_prompt": "use a formal tone"},
+            ),
+            TranslationRequest(
+                text="Goodbye",
+                target_language="fr",
+                source_language="en",
+                metadata={"custom_prompt": "use a formal tone"},
+            ),
+        ]
+
+        provider.translate_batch(requests)
+
+        payload = mock_post.call_args[1]["json"]
+        system = payload["messages"][0]["content"]
+        user = payload["messages"][1]["content"]
+        # System prompt = base instructions + custom prompt + strict JSON rule.
+        assert "professional translator" in system
+        assert "ADDITIONAL CONTEXT AND INSTRUCTIONS" in system
+        assert "use a formal tone" in system
+        assert "BATCH MODE" in system
+        assert "ONLY a JSON array" in system
+        # User message = the numbered JSON list of the texts.
+        parsed = json.loads(user)
+        assert [item["text"] for item in parsed] == ["Hello", "Goodbye"]
+        assert [item["id"] for item in parsed] == [0, 1]
+
+    @patch("requests.post")
+    def test_invalid_batch_json_falls_back_to_individual(self, mock_post, provider):
+        broken_batch = self._mock_post(
+            {"choices": [{"message": {"content": "désolé, pas de JSON ici"}}], "usage": {}}
+        )
+        individuals = [
+            self._mock_post({"choices": [{"message": {"content": "Bonjour"}}], "usage": {}}),
+            self._mock_post({"choices": [{"message": {"content": "Au revoir"}}], "usage": {}}),
+            self._mock_post({"choices": [{"message": {"content": "Merci"}}], "usage": {}}),
+        ]
+        mock_post.side_effect = [broken_batch] + individuals
+        requests = [
+            TranslationRequest(text="Hello", target_language="fr"),
+            TranslationRequest(text="Goodbye", target_language="fr"),
+            TranslationRequest(text="Thank you", target_language="fr"),
+        ]
+
+        responses = provider.translate_batch(requests)
+
+        # 1 failed batch attempt + 3 individual calls.
+        assert mock_post.call_count == 4
+        assert [r.translated_text for r in responses] == ["Bonjour", "Au revoir", "Merci"]
+        assert all(r.error is None for r in responses)
+
+    @patch("requests.post")
+    def test_batch_api_error_falls_back_to_individual(self, mock_post, provider):
+        # The batch call itself fails (500) — per-item calls still translate everything.
+        failed_batch = self._mock_post({"error": "boom"}, status_code=500)
+        individuals = [
+            self._mock_post({"choices": [{"message": {"content": "Bonjour"}}], "usage": {}}),
+            self._mock_post({"choices": [{"message": {"content": "Au revoir"}}], "usage": {}}),
+        ]
+        mock_post.side_effect = [failed_batch] + individuals
+        requests = [
+            TranslationRequest(text="Hello", target_language="fr"),
+            TranslationRequest(text="Goodbye", target_language="fr"),
+        ]
+
+        responses = provider.translate_batch(requests)
+
+        assert mock_post.call_count == 3
+        assert [r.translated_text for r in responses] == ["Bonjour", "Au revoir"]
+
+    @patch("requests.post")
+    def test_wrong_batch_length_falls_back_to_individual(self, mock_post, provider):
+        # A JSON answer with a missing item is NOT trusted → fallback.
+        short_batch = self._batch_response(["Bonjour", "Au revoir"])
+        individuals = [
+            self._mock_post({"choices": [{"message": {"content": "Bonjour"}}], "usage": {}}),
+            self._mock_post({"choices": [{"message": {"content": "Au revoir"}}], "usage": {}}),
+            self._mock_post({"choices": [{"message": {"content": "Merci"}}], "usage": {}}),
+        ]
+        mock_post.side_effect = [short_batch] + individuals
+        requests = [
+            TranslationRequest(text="Hello", target_language="fr"),
+            TranslationRequest(text="Goodbye", target_language="fr"),
+            TranslationRequest(text="Thank you", target_language="fr"),
+        ]
+
+        responses = provider.translate_batch(requests)
+
+        assert mock_post.call_count == 4
+        assert [r.translated_text for r in responses] == ["Bonjour", "Au revoir", "Merci"]
+
+    @patch("requests.post")
+    def test_mixed_metadata_skips_batch(self, mock_post, provider):
+        mock_post.side_effect = [
+            self._mock_post({"choices": [{"message": {"content": "Bonjour"}}], "usage": {}}),
+            self._mock_post({"choices": [{"message": {"content": "Au revoir"}}], "usage": {}}),
+        ]
+        requests = [
+            TranslationRequest(
+                text="Hello", target_language="fr", metadata={"custom_prompt": "formal"}
+            ),
+            TranslationRequest(
+                text="Goodbye", target_language="fr", metadata={"custom_prompt": "casual"}
+            ),
+        ]
+
+        responses = provider.translate_batch(requests)
+
+        # Two individual calls, no numbered-JSON batch attempt.
+        assert mock_post.call_count == 2
+        assert [r.translated_text for r in responses] == ["Bonjour", "Au revoir"]
+        for call in mock_post.call_args_list:
+            assert call[1]["json"]["messages"][1]["content"] in ("Hello", "Goodbye")
+
+    @patch("requests.post")
+    def test_mixed_language_pair_skips_batch(self, mock_post, provider):
+        mock_post.side_effect = [
+            self._mock_post({"choices": [{"message": {"content": "Bonjour"}}], "usage": {}}),
+            self._mock_post({"choices": [{"message": {"content": "Hola"}}], "usage": {}}),
+        ]
+        requests = [
+            TranslationRequest(text="Hello", target_language="fr"),
+            TranslationRequest(text="Hello", target_language="es"),
+        ]
+
+        responses = provider.translate_batch(requests)
+
+        assert mock_post.call_count == 2
+        assert [r.translated_text for r in responses] == ["Bonjour", "Hola"]
+
+    @patch("requests.post")
+    def test_single_request_is_individual(self, mock_post, provider):
+        mock_post.return_value = self._mock_post(
+            {"choices": [{"message": {"content": "Bonjour"}}], "usage": {}}
+        )
+        requests = [TranslationRequest(text="Hello", target_language="fr")]
+
+        responses = provider.translate_batch(requests)
+
+        assert mock_post.call_count == 1
+        assert responses[0].translated_text == "Bonjour"
+        # The user message is the raw text, not a numbered JSON list.
+        user_message = mock_post.call_args[1]["json"]["messages"][1]["content"]
+        assert user_message == "Hello"
+
+    def test_empty_batch_returns_empty(self, provider):
+        assert provider.translate_batch([]) == []
+
+
+class TestDeepSeekProviderError:
+    def test_error_carries_code_and_message(self):
+        err = DeepSeekProviderError(DEEPSEEK_TIMEOUT, "timed out", details={"wait": 1})
+        assert err.code == DEEPSEEK_TIMEOUT
+        assert err.message == "timed out"
+        assert err.details == {"wait": 1}
+
+    def test_rate_limited_code_exists(self):
+        # Sanity: the retryable codes used by the provider are importable.
+        assert DEEPSEEK_RATE_LIMITED == "DEEPSEEK_RATE_LIMITED"
diff --git a/tests/test_providers/test_minimax_provider.py b/tests/test_providers/test_minimax_provider.py
index 3ab563a..9569134 100644
--- a/tests/test_providers/test_minimax_provider.py
+++ b/tests/test_providers/test_minimax_provider.py
@@ -7,8 +7,15 @@ Validates Bug 1 fix:
 - ``is_available()`` / ``health_check()`` tolerate a missing ``/models`` path
   (Minimax does not document it) and only mark the provider down on 401/network error
 - translation success, 429 retry, 401 handling
+
+Batch mode (ported from the OpenAI provider):
+- same language pair + metadata chunk → ONE numbered-JSON request for all texts
+- unparseable/failed batch answer → per-item fallback, every text still translated
+- mixed metadata or a single text → no batch (individual requests)
 """
 
+import json
+
 import pytest
 from unittest.mock import patch, MagicMock
 from requests.exceptions import Timeout
@@ -159,3 +166,198 @@ class TestMinimaxProviderError:
         assert err.code == MINIMAX_TIMEOUT
         assert err.message == "timed out"
         assert err.details == {"wait": 1}
+
+
+class TestMinimaxBatchTranslation:
+    """Batch mode: one numbered-JSON request per same pair/metadata chunk."""
+
+    @pytest.fixture
+    def provider(self):
+        return MinimaxTranslationProvider(api_key="k", max_retries=0)
+
+    def _mock_post(self, payload, status_code=200):
+        mock_response = MagicMock()
+        mock_response.status_code = status_code
+        mock_response.json.return_value = payload
+        mock_response.text = ""
+        return mock_response
+
+    def _batch_response(self, translations):
+        """Mock a 200 response whose content is a numbered JSON array."""
+        content = json.dumps(
+            [{"id": i, "translation": t} for i, t in enumerate(translations)]
+        )
+        return self._mock_post({"choices": [{"message": {"content": content}}], "usage": {}})
+
+    @patch("requests.post")
+    def test_batch_of_three_uses_single_request(self, mock_post, provider):
+        mock_post.return_value = self._batch_response(["Bonjour", "Au revoir", "Merci"])
+        requests = [
+            TranslationRequest(text="Hello", target_language="fr"),
+            TranslationRequest(text="Goodbye", target_language="fr"),
+            TranslationRequest(text="Thank you", target_language="fr"),
+        ]
+
+        responses = provider.translate_batch(requests)
+
+        assert mock_post.call_count == 1
+        assert [r.translated_text for r in responses] == ["Bonjour", "Au revoir", "Merci"]
+        assert all(r.provider_name == "minimax" for r in responses)
+        assert all(r.error is None for r in responses)
+        # The single call went to the public chat completions endpoint.
+        assert mock_post.call_args[0][0] == "https://api.minimax.io/v1/chat/completions"
+
+    @patch("requests.post")
+    def test_batch_request_payload_is_numbered_json_with_instructions(self, mock_post, provider):
+        mock_post.return_value = self._batch_response(["Bonjour", "Au revoir"])
+        requests = [
+            TranslationRequest(
+                text="Hello",
+                target_language="fr",
+                source_language="en",
+                metadata={"custom_prompt": "use a formal tone"},
+            ),
+            TranslationRequest(
+                text="Goodbye",
+                target_language="fr",
+                source_language="en",
+                metadata={"custom_prompt": "use a formal tone"},
+            ),
+        ]
+
+        provider.translate_batch(requests)
+
+        payload = mock_post.call_args[1]["json"]
+        system = payload["messages"][0]["content"]
+        user = payload["messages"][1]["content"]
+        # System prompt = base instructions + custom prompt + strict JSON rule.
+        assert "professional translator" in system
+        assert "ADDITIONAL CONTEXT AND INSTRUCTIONS" in system
+        assert "use a formal tone" in system
+        assert "BATCH MODE" in system
+        assert "ONLY a JSON array" in system
+        # User message = the numbered JSON list of the texts.
+        parsed = json.loads(user)
+        assert [item["text"] for item in parsed] == ["Hello", "Goodbye"]
+        assert [item["id"] for item in parsed] == [0, 1]
+
+    @patch("requests.post")
+    def test_invalid_batch_json_falls_back_to_individual(self, mock_post, provider):
+        broken_batch = self._mock_post(
+            {"choices": [{"message": {"content": "désolé, pas de JSON ici"}}], "usage": {}}
+        )
+        individuals = [
+            self._mock_post({"choices": [{"message": {"content": "Bonjour"}}], "usage": {}}),
+            self._mock_post({"choices": [{"message": {"content": "Au revoir"}}], "usage": {}}),
+            self._mock_post({"choices": [{"message": {"content": "Merci"}}], "usage": {}}),
+        ]
+        mock_post.side_effect = [broken_batch] + individuals
+        requests = [
+            TranslationRequest(text="Hello", target_language="fr"),
+            TranslationRequest(text="Goodbye", target_language="fr"),
+            TranslationRequest(text="Thank you", target_language="fr"),
+        ]
+
+        responses = provider.translate_batch(requests)
+
+        # 1 failed batch attempt + 3 individual calls.
+        assert mock_post.call_count == 4
+        assert [r.translated_text for r in responses] == ["Bonjour", "Au revoir", "Merci"]
+        assert all(r.error is None for r in responses)
+
+    @patch("requests.post")
+    def test_batch_api_error_falls_back_to_individual(self, mock_post, provider):
+        # The batch call itself fails (500) — per-item calls still translate everything.
+        failed_batch = self._mock_post({"error": "boom"}, status_code=500)
+        individuals = [
+            self._mock_post({"choices": [{"message": {"content": "Bonjour"}}], "usage": {}}),
+            self._mock_post({"choices": [{"message": {"content": "Au revoir"}}], "usage": {}}),
+        ]
+        mock_post.side_effect = [failed_batch] + individuals
+        requests = [
+            TranslationRequest(text="Hello", target_language="fr"),
+            TranslationRequest(text="Goodbye", target_language="fr"),
+        ]
+
+        responses = provider.translate_batch(requests)
+
+        assert mock_post.call_count == 3
+        assert [r.translated_text for r in responses] == ["Bonjour", "Au revoir"]
+
+    @patch("requests.post")
+    def test_wrong_batch_length_falls_back_to_individual(self, mock_post, provider):
+        # A JSON answer with a missing item is NOT trusted → fallback.
+        short_batch = self._batch_response(["Bonjour", "Au revoir"])
+        individuals = [
+            self._mock_post({"choices": [{"message": {"content": "Bonjour"}}], "usage": {}}),
+            self._mock_post({"choices": [{"message": {"content": "Au revoir"}}], "usage": {}}),
+            self._mock_post({"choices": [{"message": {"content": "Merci"}}], "usage": {}}),
+        ]
+        mock_post.side_effect = [short_batch] + individuals
+        requests = [
+            TranslationRequest(text="Hello", target_language="fr"),
+            TranslationRequest(text="Goodbye", target_language="fr"),
+            TranslationRequest(text="Thank you", target_language="fr"),
+        ]
+
+        responses = provider.translate_batch(requests)
+
+        assert mock_post.call_count == 4
+        assert [r.translated_text for r in responses] == ["Bonjour", "Au revoir", "Merci"]
+
+    @patch("requests.post")
+    def test_mixed_metadata_skips_batch(self, mock_post, provider):
+        mock_post.side_effect = [
+            self._mock_post({"choices": [{"message": {"content": "Bonjour"}}], "usage": {}}),
+            self._mock_post({"choices": [{"message": {"content": "Au revoir"}}], "usage": {}}),
+        ]
+        requests = [
+            TranslationRequest(
+                text="Hello", target_language="fr", metadata={"custom_prompt": "formal"}
+            ),
+            TranslationRequest(
+                text="Goodbye", target_language="fr", metadata={"custom_prompt": "casual"}
+            ),
+        ]
+
+        responses = provider.translate_batch(requests)
+
+        # Two individual calls, no numbered-JSON batch attempt.
+        assert mock_post.call_count == 2
+        assert [r.translated_text for r in responses] == ["Bonjour", "Au revoir"]
+        for call in mock_post.call_args_list:
+            assert call[1]["json"]["messages"][1]["content"] in ("Hello", "Goodbye")
+
+    @patch("requests.post")
+    def test_mixed_language_pair_skips_batch(self, mock_post, provider):
+        mock_post.side_effect = [
+            self._mock_post({"choices": [{"message": {"content": "Bonjour"}}], "usage": {}}),
+            self._mock_post({"choices": [{"message": {"content": "Hola"}}], "usage": {}}),
+        ]
+        requests = [
+            TranslationRequest(text="Hello", target_language="fr"),
+            TranslationRequest(text="Hello", target_language="es"),
+        ]
+
+        responses = provider.translate_batch(requests)
+
+        assert mock_post.call_count == 2
+        assert [r.translated_text for r in responses] == ["Bonjour", "Hola"]
+
+    @patch("requests.post")
+    def test_single_request_is_individual(self, mock_post, provider):
+        mock_post.return_value = self._mock_post(
+            {"choices": [{"message": {"content": "Bonjour"}}], "usage": {}}
+        )
+        requests = [TranslationRequest(text="Hello", target_language="fr")]
+
+        responses = provider.translate_batch(requests)
+
+        assert mock_post.call_count == 1
+        assert responses[0].translated_text == "Bonjour"
+        # The user message is the raw text, not a numbered JSON list.
+        user_message = mock_post.call_args[1]["json"]["messages"][1]["content"]
+        assert user_message == "Hello"
+
+    def test_empty_batch_returns_empty(self, provider):
+        assert provider.translate_batch([]) == []