fix(ai): Agent chat handler 精确选择 FC-capable provider + 环境变量适配

- chat_handler: 使用 get_provider("claude") 精确获取，避免 resolve fallback 到 Ollama
- ProviderRegistry: 新增 get_provider() 方法（无 health check，无 fallback）
- orchestrator: 从 ANTHROPIC_DEFAULT_SONNET_MODEL 读取模型名，兼容智谱代理
- erp-server: Claude provider 注册优先读 ANTHROPIC_AUTH_TOKEN + ANTHROPIC_BASE_URL

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

crates/erp-ai/src/agent/orchestrator.rs

@@ -51,7 +51,8 @@ impl AgentOrchestrator {
                     messages.clone(),
                     tools.clone(),
                     system_prompt,
-                    "auto",
+                    &std::env::var("ANTHROPIC_DEFAULT_SONNET_MODEL")
+                        .unwrap_or_else(|_| "claude-sonnet-4-6".to_string()),
                     0.7,
                     2048,
                 )

crates/erp-ai/src/handler/chat_handler.rs

@@ -128,14 +128,16 @@ where
         tool_call_id: None,
     });
 
-    // 解析 Provider
-    let resolved = ai_state
+    // 解析 Provider — Agent 需要 Function Calling，精确获取 Claude/OpenAI
+    let provider_arc = ai_state
         .provider_registry
-        .resolve("auto")
-        .await
-        .map_err(|e| {
-            tracing::error!(error = %e, "AI provider resolve failed");
-            erp_core::error::AppError::Internal("AI 服务暂时不可用，请稍后再试".into())
+        .get_provider("claude")
+        .or_else(|| ai_state.provider_registry.get_provider("openai"))
+        .ok_or_else(|| {
+            tracing::error!("No FC-capable provider found (need claude or openai)");
+            erp_core::error::AppError::Internal(
+                "AI Agent 暂时不可用，需要 Claude 或 OpenAI 提供商".into(),
+            )
         })?;
 
     // 构建 ToolRegistry — Phase 0 只有 query_patient_vitals
@@ -159,7 +161,6 @@ where
     );
 
     // 执行 Agent ReAct 循环
-    let provider_arc = resolved.into_arc();
     let orchestrator = AgentOrchestrator::new(provider_arc, std::sync::Arc::new(registry));
     let result = orchestrator
         .run(SYSTEM_PROMPT, &mut messages, &tool_ctx)

crates/erp-ai/src/provider/registry.rs

@@ -105,6 +105,11 @@ impl ProviderRegistry {
     pub fn provider_names(&self) -> Vec<String> {
         self.entries.iter().map(|e| e.key().to_string()).collect()
     }
+
+    /// 精确获取指定名称的 provider（不做 health check，不做 fallback）
+    pub fn get_provider(&self, name: &str) -> Option<Arc<dyn AiProvider>> {
+        self.entries.get(name).map(|e| e.provider.clone())
+    }
 }
 
 pub struct ResolvedProvider {

crates/erp-server/src/main.rs

@@ -477,13 +477,21 @@ async fn main() -> anyhow::Result<()> {
         // 构建多 Provider 注册表
         let registry = std::sync::Arc::new(erp_ai::provider::registry::ProviderRegistry::new());
 
-        // 始终注册默认 Claude provider（兼容旧配置）
+        // 始终注册默认 Claude provider — 优先用环境变量
         {
-            let mut claude =
-                erp_ai::provider::claude::ClaudeProvider::new(config.ai.api_key.clone());
-            if let Some(ref base_url) = config.ai.base_url {
-                claude = claude.with_base_url(base_url.clone());
-            }
+            let api_key = if !config.ai.api_key.is_empty() {
+                config.ai.api_key.clone()
+            } else {
+                std::env::var("ANTHROPIC_AUTH_TOKEN")
+                    .or_else(|_| std::env::var("ANTHROPIC_API_KEY"))
+                    .unwrap_or_default()
+            };
+            let base_url = std::env::var("ANTHROPIC_BASE_URL")
+                .ok()
+                .or_else(|| config.ai.base_url.clone())
+                .unwrap_or_else(|| "https://api.anthropic.com".to_string());
+            let claude =
+                erp_ai::provider::claude::ClaudeProvider::new(api_key).with_base_url(base_url);
             registry.register("claude".to_string(), std::sync::Arc::new(claude));
         }