feat(stt): support multi-model STT with parallel execution and consensus NLU extraction

ai procurement/app/config.py

@@ -37,9 +37,30 @@ class Settings(BaseSettings):
     LLM_MODEL: str = "gpt-4o-mini"
     LLM_TIMEOUT_SECONDS: float = 60.0
 
-    # STT provider — any OpenAI-compatible /audio/transcriptions endpoint.
-    # Falls back to the LLM provider when unset. Note: some providers
-    # (e.g. DeepSeek) have no audio API — voice stays disabled gracefully.
+    # STT providers — support multiple models/APIs in parallel.
+    # 1. JSON list: [{"name": "m1", "base_url": "...", "api_key": "...", "model": "..."}, ...]
+    STT_PROVIDERS_JSON: str = ""
+
+    # 2. Individual provider variables (up to 3 distinct STT models)
+    STT_PROVIDER_1_NAME: str = "model-1"
+    STT_PROVIDER_1_BASE_URL: str = ""
+    STT_PROVIDER_1_API_KEY: str = ""
+    STT_PROVIDER_1_MODEL: str = ""
+    STT_PROVIDER_1_LANGUAGE: str = "fa"
+
+    STT_PROVIDER_2_NAME: str = "model-2"
+    STT_PROVIDER_2_BASE_URL: str = ""
+    STT_PROVIDER_2_API_KEY: str = ""
+    STT_PROVIDER_2_MODEL: str = ""
+    STT_PROVIDER_2_LANGUAGE: str = "fa"
+
+    STT_PROVIDER_3_NAME: str = "model-3"
+    STT_PROVIDER_3_BASE_URL: str = ""
+    STT_PROVIDER_3_API_KEY: str = ""
+    STT_PROVIDER_3_MODEL: str = ""
+    STT_PROVIDER_3_LANGUAGE: str = "fa"
+
+    # Legacy single STT provider fallback:
     STT_BASE_URL: str = ""
     STT_API_KEY: str = ""
     STT_MODEL: str = "whisper-1"
@@ -53,6 +74,49 @@ class Settings(BaseSettings):
     def stt_api_key(self) -> str:
         return self.STT_API_KEY or self.AI_API_KEY
 
+    @property
+    def stt_providers(self) -> list[dict]:
+        import json
+        if self.STT_PROVIDERS_JSON:
+            try:
+                data = json.loads(self.STT_PROVIDERS_JSON)
+                if isinstance(data, list) and len(data) > 0:
+                    return data
+            except Exception:
+                pass
+
+        # Check explicit STT_PROVIDER_1 / 2 / 3
+        custom_list: list[dict] = []
+        for idx in (1, 2, 3):
+            b_url = getattr(self, f"STT_PROVIDER_{idx}_BASE_URL")
+            key = getattr(self, f"STT_PROVIDER_{idx}_API_KEY")
+            model = getattr(self, f"STT_PROVIDER_{idx}_MODEL")
+            name = getattr(self, f"STT_PROVIDER_{idx}_NAME")
+            lang = getattr(self, f"STT_PROVIDER_{idx}_LANGUAGE") or "fa"
+            if b_url and key:
+                custom_list.append({
+                    "name": name or f"model-{idx}",
+                    "base_url": b_url,
+                    "api_key": key,
+                    "model": model or self.STT_MODEL,
+                    "language": lang,
+                    "timeout": 30.0,
+                })
+        if custom_list:
+            return custom_list
+
+        # Fallback to single legacy STT provider if set
+        if self.stt_base_url and self.stt_api_key:
+            return [{
+                "name": "default",
+                "base_url": self.stt_base_url,
+                "api_key": self.stt_api_key,
+                "model": self.STT_MODEL,
+                "language": self.STT_LANGUAGE,
+                "timeout": 30.0,
+            }]
+        return []
+
     # PostgreSQL — same instance/database as the api service.
     DATABASE_URL: str = "postgresql+asyncpg://postgres:postgres@localhost:5432/procurement"