Feat: custom models api params support

backend/src/agents/api/llm_overrides.py

@@ -0,0 +1,100 @@
+import json
+from typing import Dict, Optional, Tuple
+
+from pydantic import BaseModel
+
+
+class TaskModelOverride(BaseModel):
+    """
+    Per-task LLM override.
+
+    Use this to target a specific provider/model/base_url for a single task,
+    e.g. deep_research_writer or deep_research_planner.
+    """
+
+    provider: Optional[str] = None
+    model: Optional[str] = None
+    base_url: Optional[str] = None
+    provider_type: Optional[str] = None
+
+
+class LLMOverrides(BaseModel):
+    """
+    Request-scoped LLM configuration overrides.
+
+    Precedence:
+      1) task_models overrides (per task)
+      2) top-level overrides (provider/model/base_url/provider_type)
+      3) server defaults/config manager
+
+    Notes:
+      - api_keys is optional and not required for typical usage.
+      - If api_keys is omitted, the Authorization Bearer token is used as
+        the fallback key for the selected provider.
+      - api_keys is a map of provider name -> key. Provider names must match:
+        - top-level provider (provider)
+        - any per-task provider in task_models
+        - any custom provider names configured in the system
+    """
+
+    provider: Optional[str] = None
+    model: Optional[str] = None
+    base_url: Optional[str] = None
+    provider_type: Optional[str] = None
+    api_keys: Optional[Dict[str, str]] = None
+    task_models: Optional[Dict[str, TaskModelOverride]] = None
+
+
+def parse_llm_config_json(llm_config_json: Optional[str]) -> Optional[LLMOverrides]:
+    """
+    Parse llm_config_json (stringified JSON) into LLMOverrides.
+    Returns None when not provided.
+    """
+    if not llm_config_json:
+        return None
+
+    data = json.loads(llm_config_json)
+    return LLMOverrides.model_validate(data)
+
+
+def resolve_llm_overrides(
+    api_key: str,
+    llm_config: Optional[LLMOverrides],
+) -> Tuple[Dict[str, str], Optional[dict], str]:
+    """
+    Resolve request-scoped LLM overrides into api_keys and override maps.
+
+    If api_keys is not provided, the Authorization Bearer token is used as the
+    fallback key for the chosen provider and any task-specific providers.
+    If api_keys is provided, its keys must match the provider names used in the
+    overrides (top-level provider and any task_models providers).
+    """
+    if not llm_config:
+        return {"sambanova": api_key}, None, "sambanova"
+
+    api_keys = dict(llm_config.api_keys or {})
+    provider = llm_config.provider or "sambanova"
+
+    if api_key:
+        api_keys.setdefault(provider, api_key)
+        if llm_config.task_models:
+            for task_config in llm_config.task_models.values():
+                if task_config.provider:
+                    api_keys.setdefault(task_config.provider, api_key)
+
+    overrides = {
+        "provider": llm_config.provider,
+        "model": llm_config.model,
+        "base_url": llm_config.base_url,
+        "provider_type": llm_config.provider_type,
+        "task_models": (
+            {
+                task: task_config.model_dump(exclude_none=True)
+                for task, task_config in llm_config.task_models.items()
+            }
+            if llm_config.task_models
+            else None
+        ),
+    }
+
+    return api_keys, overrides, provider