fix: support LLM provider compatibility options

Closes #36

crates/webclaw-llm/src/chain.rs

@@ -34,7 +34,7 @@ impl ProviderChain {
             providers.push(Box::new(openai));
         }
 
-        if let Some(anthropic) = AnthropicProvider::new(None, None) {
+        if let Some(anthropic) = AnthropicProvider::with_base_url(None, None, None) {
             debug!("anthropic configured, adding to chain");
             providers.push(Box::new(anthropic));
         }

crates/webclaw-llm/src/providers/anthropic.rs

@@ -10,23 +10,38 @@ use crate::provider::{CompletionRequest, LlmProvider};
 
 use super::load_api_key;
 
-const ANTHROPIC_API_URL: &str = "https://api.anthropic.com/v1/messages";
+const DEFAULT_ANTHROPIC_BASE_URL: &str = "https://api.anthropic.com/v1";
 const ANTHROPIC_VERSION: &str = "2023-06-01";
 
 pub struct AnthropicProvider {
     client: reqwest::Client,
     key: String,
+    base_url: String,
     default_model: String,
 }
 
 impl AnthropicProvider {
     /// Returns `None` if no API key is available (param or env).
     pub fn new(key_override: Option<String>, model: Option<String>) -> Option<Self> {
+        Self::with_base_url(key_override, None, model)
+    }
+
+    /// Returns `None` if no API key is available (param or env).
+    pub fn with_base_url(
+        key_override: Option<String>,
+        base_url: Option<String>,
+        model: Option<String>,
+    ) -> Option<Self> {
         let key = load_api_key(key_override, "ANTHROPIC_API_KEY")?;
 
         Some(Self {
             client: reqwest::Client::new(),
             key,
+            base_url: base_url
+                .or_else(|| std::env::var("ANTHROPIC_BASE_URL").ok())
+                .unwrap_or_else(|| DEFAULT_ANTHROPIC_BASE_URL.into())
+                .trim_end_matches('/')
+                .to_string(),
             default_model: model.unwrap_or_else(|| "claude-sonnet-4-20250514".into()),
         })
     }
@@ -34,6 +49,14 @@ impl AnthropicProvider {
     pub fn default_model(&self) -> &str {
         &self.default_model
     }
+
+    fn messages_url(&self) -> String {
+        if self.base_url.ends_with("/messages") {
+            self.base_url.clone()
+        } else {
+            format!("{}/messages", self.base_url)
+        }
+    }
 }
 
 #[async_trait]
@@ -74,7 +97,7 @@ impl LlmProvider for AnthropicProvider {
 
         let resp = self
             .client
-            .post(ANTHROPIC_API_URL)
+            .post(self.messages_url())
             .header("x-api-key", &self.key)
             .header("anthropic-version", ANTHROPIC_VERSION)
             .header("content-type", "application/json")
@@ -135,6 +158,11 @@ mod tests {
         assert_eq!(provider.name(), "anthropic");
         assert_eq!(provider.default_model, "claude-sonnet-4-20250514");
         assert_eq!(provider.key, "sk-ant-test");
+        assert_eq!(provider.base_url, "https://api.anthropic.com/v1");
+        assert_eq!(
+            provider.messages_url(),
+            "https://api.anthropic.com/v1/messages"
+        );
     }
 
     #[test]
@@ -151,6 +179,35 @@ mod tests {
         assert_eq!(provider.default_model(), "claude-sonnet-4-20250514");
     }
 
+    #[test]
+    fn custom_base_url_appends_messages_path() {
+        let provider = AnthropicProvider::with_base_url(
+            Some("sk-ant-test".into()),
+            Some("https://proxy.example.test/anthropic/v1/".into()),
+            None,
+        )
+        .unwrap();
+        assert_eq!(provider.base_url, "https://proxy.example.test/anthropic/v1");
+        assert_eq!(
+            provider.messages_url(),
+            "https://proxy.example.test/anthropic/v1/messages"
+        );
+    }
+
+    #[test]
+    fn custom_full_messages_url_is_not_doubled() {
+        let provider = AnthropicProvider::with_base_url(
+            Some("sk-ant-test".into()),
+            Some("https://proxy.example.test/v1/messages".into()),
+            None,
+        )
+        .unwrap();
+        assert_eq!(
+            provider.messages_url(),
+            "https://proxy.example.test/v1/messages"
+        );
+    }
+
     // Env var fallback tests mutate process-global state and race with parallel tests.
     // The code path is trivial (load_api_key -> env::var().ok()). Run in isolation if needed:
     //   cargo test -p webclaw-llm env_var -- --ignored --test-threads=1

crates/webclaw-llm/src/providers/openai.rs

@@ -13,6 +13,50 @@ pub struct OpenAiProvider {
     key: String,
     base_url: String,
     default_model: String,
+    response_format: OpenAiResponseFormat,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum OpenAiResponseFormat {
+    JsonObject,
+    JsonSchema,
+    Text,
+}
+
+impl OpenAiResponseFormat {
+    fn from_env() -> Self {
+        std::env::var("OPENAI_RESPONSE_FORMAT_TYPE")
+            .ok()
+            .and_then(|value| Self::parse(&value))
+            .unwrap_or(Self::JsonObject)
+    }
+
+    fn parse(value: &str) -> Option<Self> {
+        match value.trim().to_ascii_lowercase().as_str() {
+            "" | "json_object" => Some(Self::JsonObject),
+            "json_schema" => Some(Self::JsonSchema),
+            "text" => Some(Self::Text),
+            _ => None,
+        }
+    }
+
+    fn as_response_format(self) -> serde_json::Value {
+        match self {
+            Self::JsonObject => json!({ "type": "json_object" }),
+            Self::JsonSchema => json!({
+                "type": "json_schema",
+                "json_schema": {
+                    "name": "webclaw_response",
+                    "schema": {
+                        "type": "object",
+                        "additionalProperties": true
+                    },
+                    "strict": false
+                }
+            }),
+            Self::Text => json!({ "type": "text" }),
+        }
+    }
 }
 
 impl OpenAiProvider {
@@ -31,23 +75,15 @@ impl OpenAiProvider {
                 .or_else(|| std::env::var("OPENAI_BASE_URL").ok())
                 .unwrap_or_else(|| "https://api.openai.com/v1".into()),
             default_model: model.unwrap_or_else(|| "gpt-4o-mini".into()),
+            response_format: OpenAiResponseFormat::from_env(),
         })
     }
 
     pub fn default_model(&self) -> &str {
         &self.default_model
     }
-}
-
-#[async_trait]
-impl LlmProvider for OpenAiProvider {
-    async fn complete(&self, request: &CompletionRequest) -> Result<String, LlmError> {
-        let model = if request.model.is_empty() {
-            &self.default_model
-        } else {
-            &request.model
-        };
 
+    fn request_body(&self, request: &CompletionRequest, model: &str) -> serde_json::Value {
         let messages: Vec<serde_json::Value> = request
             .messages
             .iter()
@@ -60,7 +96,7 @@ impl LlmProvider for OpenAiProvider {
         });
 
         if request.json_mode {
-            body["response_format"] = json!({ "type": "json_object" });
+            body["response_format"] = self.response_format.as_response_format();
         }
         if let Some(temp) = request.temperature {
             body["temperature"] = json!(temp);
@@ -69,6 +105,21 @@ impl LlmProvider for OpenAiProvider {
             body["max_tokens"] = json!(max);
         }
 
+        body
+    }
+}
+
+#[async_trait]
+impl LlmProvider for OpenAiProvider {
+    async fn complete(&self, request: &CompletionRequest) -> Result<String, LlmError> {
+        let model = if request.model.is_empty() {
+            &self.default_model
+        } else {
+            &request.model
+        };
+
+        let body = self.request_body(request, model);
+
         let url = format!("{}/chat/completions", self.base_url);
         let resp = self
             .client
@@ -136,6 +187,7 @@ mod tests {
         assert_eq!(provider.default_model, "gpt-4o-mini");
         assert_eq!(provider.base_url, "https://api.openai.com/v1");
         assert_eq!(provider.key, "test-key-123");
+        assert_eq!(provider.response_format, OpenAiResponseFormat::JsonObject);
     }
 
     #[test]
@@ -161,6 +213,69 @@ mod tests {
         assert_eq!(provider.default_model(), "gpt-4o-mini");
     }
 
+    #[test]
+    fn json_mode_defaults_to_openai_json_object() {
+        let provider = OpenAiProvider::new(
+            Some("test-key".into()),
+            Some("https://api.openai.com/v1".into()),
+            None,
+        )
+        .unwrap();
+        let req = CompletionRequest {
+            model: String::new(),
+            messages: vec![],
+            temperature: None,
+            max_tokens: None,
+            json_mode: true,
+        };
+        let body = provider.request_body(&req, provider.default_model());
+        assert_eq!(body["response_format"], json!({ "type": "json_object" }));
+    }
+
+    #[test]
+    fn json_schema_response_format_for_compatible_backends() {
+        let mut provider = OpenAiProvider::new(
+            Some("test-key".into()),
+            Some("http://localhost:1234/v1".into()),
+            Some("local-model".into()),
+        )
+        .unwrap();
+        provider.response_format = OpenAiResponseFormat::JsonSchema;
+        let req = CompletionRequest {
+            model: String::new(),
+            messages: vec![],
+            temperature: None,
+            max_tokens: None,
+            json_mode: true,
+        };
+        let body = provider.request_body(&req, provider.default_model());
+        assert_eq!(body["response_format"]["type"], "json_schema");
+        assert_eq!(
+            body["response_format"]["json_schema"]["schema"]["type"],
+            "object"
+        );
+    }
+
+    #[test]
+    fn text_response_format_for_lm_studio() {
+        let mut provider = OpenAiProvider::new(
+            Some("test-key".into()),
+            Some("http://localhost:1234/v1".into()),
+            Some("local-model".into()),
+        )
+        .unwrap();
+        provider.response_format = OpenAiResponseFormat::Text;
+        let req = CompletionRequest {
+            model: String::new(),
+            messages: vec![],
+            temperature: None,
+            max_tokens: None,
+            json_mode: true,
+        };
+        let body = provider.request_body(&req, provider.default_model());
+        assert_eq!(body["response_format"], json!({ "type": "text" }));
+    }
+
     // Env var fallback tests mutate process-global state and race with parallel tests.
     // The code path is trivial (load_api_key -> env::var().ok()). Run in isolation if needed:
     //   cargo test -p webclaw-llm env_var -- --ignored --test-threads=1