Avoid requiring static API key for OAuth Login

src/llm/manager.rs

@@ -9,7 +9,7 @@
 //! `get_api_key()` calls read the new values lock-free.
 
 use crate::auth::OAuthCredentials;
-use crate::config::{LlmConfig, ProviderConfig};
+use crate::config::{ApiType, LlmConfig, ProviderConfig};
 use crate::error::{LlmError, Result};
 
 use anyhow::Context as _;
@@ -143,6 +143,32 @@ impl LlmManager {
         }
     }
 
+    /// Resolve the Anthropic provider config, preferring OAuth credentials.
+    ///
+    /// If a static provider exists in config, returns it with the API key
+    /// overridden by the OAuth token when available. If no static provider
+    /// exists but OAuth credentials are present, builds a provider from
+    /// the OAuth token alone.
+    pub async fn get_anthropic_provider(&self) -> Result<ProviderConfig> {
+        let token = self.get_anthropic_token().await?;
+        let static_provider = self.get_provider("anthropic").ok();
+
+        match (static_provider, token) {
+            (Some(mut provider), Some(token)) => {
+                provider.api_key = token;
+                Ok(provider)
+            }
+            (Some(provider), None) => Ok(provider),
+            (None, Some(token)) => Ok(ProviderConfig {
+                api_type: ApiType::Anthropic,
+                base_url: "https://api.anthropic.com".to_string(),
+                api_key: token,
+                name: None,
+            }),
+            (None, None) => Err(LlmError::UnknownProvider("anthropic".to_string()).into()),
+        }
+    }
+
     /// Get the appropriate API key for a provider.
     pub fn get_api_key(&self, provider_id: &str) -> Result<String> {
         let provider = self.get_provider(provider_id)?;

src/llm/model.rs

@@ -76,17 +76,16 @@ impl SpacebotModel {
             .map(|(provider, _)| provider)
             .unwrap_or("anthropic");
 
-        let mut provider_config = self
-            .llm_manager
-            .get_provider(provider_id)
-            .map_err(|e| CompletionError::ProviderError(e.to_string()))?;
-
-        // For Anthropic, prefer OAuth token from auth.json over static config key
-        if provider_id == "anthropic"
-            && let Ok(Some(token)) = self.llm_manager.get_anthropic_token().await
-        {
-            provider_config.api_key = token;
-        }
+        let provider_config = if provider_id == "anthropic" {
+            self.llm_manager
+                .get_anthropic_provider()
+                .await
+                .map_err(|e| CompletionError::ProviderError(e.to_string()))?
+        } else {
+            self.llm_manager
+                .get_provider(provider_id)
+                .map_err(|e| CompletionError::ProviderError(e.to_string()))?
+        };
 
         if provider_id == "zai-coding-plan" || provider_id == "zhipu" {
             let display_name = if provider_id == "zhipu" {