feat(drivers): add Vertex AI driver with OAuth authentication

crates/openfang-runtime/src/drivers/mod.rs

@@ -9,15 +9,16 @@ pub mod copilot;
 pub mod fallback;
 pub mod gemini;
 pub mod openai;
+pub mod vertex;
 
 use crate::llm_driver::{DriverConfig, LlmDriver, LlmError};
 use openfang_types::model_catalog::{
     AI21_BASE_URL, ANTHROPIC_BASE_URL, CEREBRAS_BASE_URL, COHERE_BASE_URL, DEEPSEEK_BASE_URL,
     FIREWORKS_BASE_URL, GEMINI_BASE_URL, GROQ_BASE_URL, HUGGINGFACE_BASE_URL, LMSTUDIO_BASE_URL,
     MINIMAX_BASE_URL, MISTRAL_BASE_URL, MOONSHOT_BASE_URL, OLLAMA_BASE_URL, OPENAI_BASE_URL,
-    OPENROUTER_BASE_URL, PERPLEXITY_BASE_URL, QIANFAN_BASE_URL, QWEN_BASE_URL,
-    REPLICATE_BASE_URL, SAMBANOVA_BASE_URL, TOGETHER_BASE_URL, VLLM_BASE_URL, XAI_BASE_URL,
-    ZHIPU_BASE_URL, ZHIPU_CODING_BASE_URL,
+    OPENROUTER_BASE_URL, PERPLEXITY_BASE_URL, QIANFAN_BASE_URL, QWEN_BASE_URL, REPLICATE_BASE_URL,
+    SAMBANOVA_BASE_URL, TOGETHER_BASE_URL, VLLM_BASE_URL, XAI_BASE_URL, ZHIPU_BASE_URL,
+    ZHIPU_CODING_BASE_URL,
 };
 use std::sync::Arc;
 
@@ -162,6 +163,12 @@ fn provider_defaults(provider: &str) -> Option<ProviderDefaults> {
             api_key_env: "QIANFAN_API_KEY",
             key_required: true,
         }),
+        "vertex-ai" | "vertex" | "google-vertex" => Some(ProviderDefaults {
+            // Vertex AI uses OAuth, not API keys - base_url is per-project
+            base_url: "https://us-central1-aiplatform.googleapis.com",
+            api_key_env: "GOOGLE_APPLICATION_CREDENTIALS",
+            key_required: false, // Uses OAuth service account, not API key
+        }),
         _ => None,
     }
 }
@@ -250,6 +257,39 @@ pub fn create_driver(config: &DriverConfig) -> Result<Arc<dyn LlmDriver>, LlmErr
         )));
     }
 
+    // Vertex AI — uses Google Cloud OAuth with service account credentials.
+    // Requires GOOGLE_APPLICATION_CREDENTIALS env var pointing to service account JSON,
+    // and the service account must be activated via gcloud CLI.
+    if provider == "vertex-ai" || provider == "vertex" || provider == "google-vertex" {
+        // Get project_id from environment or service account JSON
+        let project_id = std::env::var("GOOGLE_CLOUD_PROJECT")
+            .or_else(|_| std::env::var("GCLOUD_PROJECT"))
+            .or_else(|_| std::env::var("GCP_PROJECT"))
+            .or_else(|_| {
+                // Try to read from service account JSON
+                if let Ok(creds_path) = std::env::var("GOOGLE_APPLICATION_CREDENTIALS") {
+                    if let Ok(contents) = std::fs::read_to_string(&creds_path) {
+                        if let Ok(json) = serde_json::from_str::<serde_json::Value>(&contents) {
+                            if let Some(proj) = json.get("project_id").and_then(|v| v.as_str()) {
+                                return Ok(proj.to_string());
+                            }
+                        }
+                    }
+                }
+                Err(std::env::VarError::NotPresent)
+            })
+            .map_err(|_| {
+                LlmError::MissingApiKey(
+                    "Set GOOGLE_APPLICATION_CREDENTIALS or GOOGLE_CLOUD_PROJECT for Vertex AI"
+                        .to_string(),
+                )
+            })?;
+        let region = std::env::var("GOOGLE_CLOUD_REGION")
+            .or_else(|_| std::env::var("VERTEX_AI_REGION"))
+            .unwrap_or_else(|_| "us-central1".to_string());
+        return Ok(Arc::new(vertex::VertexAIDriver::new(project_id, region)));
+    }
+
     // All other providers use OpenAI-compatible format
     if let Some(defaults) = provider_defaults(provider) {
         let api_key = config
@@ -287,8 +327,8 @@ pub fn create_driver(config: &DriverConfig) -> Result<Arc<dyn LlmDriver>, LlmErr
         message: format!(
             "Unknown provider '{}'. Supported: anthropic, gemini, openai, groq, openrouter, \
              deepseek, together, mistral, fireworks, ollama, vllm, lmstudio, perplexity, \
-             cohere, ai21, cerebras, sambanova, huggingface, xai, replicate, github-copilot. \
-             Or set base_url for a custom OpenAI-compatible endpoint.",
+             cohere, ai21, cerebras, sambanova, huggingface, xai, replicate, github-copilot, \
+             vertex-ai. Or set base_url for a custom OpenAI-compatible endpoint.",
             provider
         ),
     })
@@ -318,6 +358,7 @@ pub fn known_providers() -> &'static [&'static str] {
         "xai",
         "replicate",
         "github-copilot",
+        "vertex-ai",
         "moonshot",
         "qwen",
         "minimax",
@@ -411,6 +452,7 @@ mod tests {
         assert!(providers.contains(&"xai"));
         assert!(providers.contains(&"replicate"));
         assert!(providers.contains(&"github-copilot"));
+        assert!(providers.contains(&"vertex-ai"));
         assert!(providers.contains(&"moonshot"));
         assert!(providers.contains(&"qwen"));
         assert!(providers.contains(&"minimax"));
@@ -457,4 +499,19 @@ mod tests {
         assert_eq!(d.api_key_env, "HF_API_KEY");
         assert!(d.key_required);
     }
+
+    #[test]
+    fn test_provider_defaults_vertex_ai() {
+        let d = provider_defaults("vertex-ai").unwrap();
+        assert_eq!(d.base_url, "https://us-central1-aiplatform.googleapis.com");
+        assert_eq!(d.api_key_env, "GOOGLE_APPLICATION_CREDENTIALS");
+        assert!(!d.key_required); // Uses OAuth, not API key
+    }
+
+    #[test]
+    fn test_provider_defaults_vertex_alias() {
+        let d = provider_defaults("vertex").unwrap();
+        assert_eq!(d.api_key_env, "GOOGLE_APPLICATION_CREDENTIALS");
+        assert!(!d.key_required);
+    }
 }