diff --git a/src/delm/config.py b/src/delm/config.py
index c4a0d3c..9ef62dd 100644
--- a/src/delm/config.py
+++ b/src/delm/config.py
@@ -579,38 +579,42 @@ def from_dict(cls, data: Dict[str, Any]) -> "DELMConfig":
         if data is None:
             data = {}
 
-        # Check if this is nested format (from to_dict())
         return cls(
             schema=data["schema"],
-            provider=data["provider"],
-            model=data["model"],
-            base_url=data["base_url"],
-            mode=data["mode"],
-            temperature=data["temperature"],
-            prompt_template=data["prompt_template"],
-            system_prompt=data["system_prompt"],
-            batch_size=data["batch_size"],
-            max_workers=data["max_workers"],
-            max_retries=data["max_retries"],
-            base_delay=data["base_delay"],
-            rate_limit_tokens=data["rate_limit_tokens"],
-            rate_limit_requests=data["rate_limit_requests"],
+            provider=data.get("provider", "openai"),
+            model=data.get("model", "gpt-4o-mini"),
+            base_url=data.get("base_url"),
+            mode=data.get("mode"),
+            temperature=data.get("temperature", 0.0),
+            prompt_template=data.get(
+                "prompt_template",
+                "Extract the following information from the text:\n\n{variables}\n\nText to analyze:\n{text}",
+            ),
+            system_prompt=data.get(
+                "system_prompt", "You are a precise data-extraction assistant."
+            ),
+            batch_size=data.get("batch_size", 10),
+            max_workers=data.get("max_workers", 1),
+            max_retries=data.get("max_retries", 3),
+            base_delay=data.get("base_delay", 1.0),
+            rate_limit_tokens=data.get("rate_limit_tokens"),
+            rate_limit_requests=data.get("rate_limit_requests"),
             rate_limit_period_seconds=data.get("rate_limit_period_seconds", 60.0),
-            track_cost=data["track_cost"],
-            max_budget=data["max_budget"],
-            model_input_cost_per_1M_tokens=data["model_input_cost_per_1M_tokens"],
-            model_output_cost_per_1M_tokens=data["model_output_cost_per_1M_tokens"],
+            track_cost=data.get("track_cost", True),
+            max_budget=data.get("max_budget"),
+            model_input_cost_per_1M_tokens=data.get("model_input_cost_per_1M_tokens"),
+            model_output_cost_per_1M_tokens=data.get("model_output_cost_per_1M_tokens"),
             max_completion_tokens=data.get("max_completion_tokens", 4096),
             api_kwargs=data.get("api_kwargs", {}),
-            target_column=data["target_column"],
-            drop_target_column=data["drop_target_column"],
-            splitting_strategy=data["splitting_strategy"],
-            relevance_scorer=data["relevance_scorer"],
-            score_filter=data["score_filter"],
-            cache_backend=data["cache_backend"],
-            cache_path=data["cache_path"],
-            cache_max_size_mb=data["cache_max_size_mb"],
-            cache_synchronous=data["cache_synchronous"],
+            target_column=data.get("target_column", "text"),
+            drop_target_column=data.get("drop_target_column", False),
+            splitting_strategy=data.get("splitting_strategy"),
+            relevance_scorer=data.get("relevance_scorer"),
+            score_filter=data.get("score_filter"),
+            cache_backend=data.get("cache_backend", "sqlite"),
+            cache_path=data.get("cache_path", ".delm/cache"),
+            cache_max_size_mb=data.get("cache_max_size_mb", 512),
+            cache_synchronous=data.get("cache_synchronous", "normal"),
         )
 
     @classmethod
diff --git a/tests/unit/api_kwargs/test_api_kwargs.py b/tests/unit/api_kwargs/test_api_kwargs.py
index 5bcb4a4..a7a1a2c 100644
--- a/tests/unit/api_kwargs/test_api_kwargs.py
+++ b/tests/unit/api_kwargs/test_api_kwargs.py
@@ -51,6 +51,21 @@ def test_api_kwargs_serialization_round_trip(self, simple_schema):
         restored = DELMConfig.from_dict(config_dict)
         assert restored.llm_extraction_cfg.api_kwargs == kwargs
 
+    def test_from_dict_uses_defaults_for_missing_optional_fields(self, simple_schema):
+        config = DELMConfig(schema=simple_schema)
+        config_dict = config.to_dict()
+
+        del config_dict["base_url"]
+        del config_dict["mode"]
+        del config_dict["api_kwargs"]
+        del config_dict["rate_limit_period_seconds"]
+
+        restored = DELMConfig.from_dict(config_dict)
+        assert restored.llm_extraction_cfg.base_url is None
+        assert restored.llm_extraction_cfg.mode is None
+        assert restored.llm_extraction_cfg.api_kwargs == {}
+        assert restored.llm_extraction_cfg.rate_limit_period_seconds == 60.0
+
     def test_api_kwargs_validation_rejects_non_dict(self, simple_schema):
         config = DELMConfig(schema=simple_schema, api_kwargs={"valid": True})
         config.llm_extraction_cfg.api_kwargs = "not_a_dict"