feat(noxa-9fw.2): make gemini cli the primary llm backend

- ProviderChain::default() order: Gemini CLI -> OpenAI -> Ollama -> Anthropic
- Add --llm-provider gemini arm to build_llm_provider() in noxa-cli
- Update unknown-provider error to mention gemini
- Update empty-chain error messages in CLI and MCP to mention gemini CLI
- Update MCP startup warn! to list gemini CLI as first option

crates/noxa-cli/src/main.rs

@@ -247,7 +247,7 @@ struct Cli {
     #[arg(long, num_args = 0..=1, default_missing_value = "3")]
     summarize: Option<usize>,
 
-    /// Force a specific LLM provider (ollama, openai, anthropic)
+    /// Force a specific LLM provider (gemini, ollama, openai, anthropic)
     #[arg(long, env = "NOXA_LLM_PROVIDER")]
     llm_provider: Option<String>,
 
@@ -1814,6 +1814,17 @@ async fn run_brand(cli: &Cli) -> Result<(), String> {
 async fn build_llm_provider(cli: &Cli) -> Result<Box<dyn LlmProvider>, String> {
     if let Some(ref name) = cli.llm_provider {
         match name.as_str() {
+            "gemini" => {
+                let provider = noxa_llm::providers::gemini_cli::GeminiCliProvider::new(
+                    cli.llm_model.clone(),
+                );
+                if !provider.is_available().await {
+                    return Err(
+                        "gemini CLI not found on PATH -- install it or omit --llm-provider".into(),
+                    );
+                }
+                Ok(Box::new(provider))
+            }
             "ollama" => {
                 let provider = noxa_llm::providers::ollama::OllamaProvider::new(
                     cli.llm_base_url.clone(),
@@ -1842,14 +1853,14 @@ async fn build_llm_provider(cli: &Cli) -> Result<Box<dyn LlmProvider>, String> {
                 Ok(Box::new(provider))
             }
             other => Err(format!(
-                "unknown LLM provider: {other} (use ollama, openai, or anthropic)"
+                "unknown LLM provider: {other} (use gemini, ollama, openai, or anthropic)"
             )),
         }
     } else {
         let chain = noxa_llm::ProviderChain::default().await;
         if chain.is_empty() {
             return Err(
-                "no LLM providers available -- start Ollama or set OPENAI_API_KEY / ANTHROPIC_API_KEY"
+                "no LLM providers available -- install the gemini CLI, start Ollama, or set OPENAI_API_KEY / ANTHROPIC_API_KEY"
                     .into(),
             );
         }

crates/noxa-llm/src/chain.rs

@@ -7,7 +7,10 @@ use tracing::{debug, warn};
 use crate::error::LlmError;
 use crate::provider::{CompletionRequest, LlmProvider};
 use crate::providers::{
-    anthropic::AnthropicProvider, ollama::OllamaProvider, openai::OpenAiProvider,
+    anthropic::AnthropicProvider,
+    gemini_cli::GeminiCliProvider,
+    ollama::OllamaProvider,
+    openai::OpenAiProvider,
 };
 
 pub struct ProviderChain {
@@ -15,12 +18,26 @@ pub struct ProviderChain {
 }
 
 impl ProviderChain {
-    /// Build the default chain: Ollama -> OpenAI -> Anthropic.
-    /// Ollama is always added (availability checked at call time).
+    /// Build the default chain: Gemini CLI -> OpenAI -> Ollama -> Anthropic.
+    /// Gemini CLI is the primary backend (subprocess-based, requires `gemini` on PATH).
     /// Cloud providers are only added if their API keys are configured.
+    /// Ollama is added if reachable at call time.
     pub async fn default() -> Self {
         let mut providers: Vec<Box<dyn LlmProvider>> = Vec::new();
 
+        let gemini = GeminiCliProvider::new(None);
+        if gemini.is_available().await {
+            debug!("gemini cli available, adding as primary provider");
+            providers.push(Box::new(gemini));
+        } else {
+            debug!("gemini cli not found on PATH, skipping");
+        }
+
+        if let Some(openai) = OpenAiProvider::new(None, None, None) {
+            debug!("openai configured, adding to chain");
+            providers.push(Box::new(openai));
+        }
+
         let ollama = OllamaProvider::new(None, None);
         if ollama.is_available().await {
             debug!("ollama is available, adding to chain");
@@ -29,11 +46,6 @@ impl ProviderChain {
             debug!("ollama not available, skipping");
         }
 
-        if let Some(openai) = OpenAiProvider::new(None, None, None) {
-            debug!("openai configured, adding to chain");
-            providers.push(Box::new(openai));
-        }
-
         if let Some(anthropic) = AnthropicProvider::new(None, None) {
             debug!("anthropic configured, adding to chain");
             providers.push(Box::new(anthropic));
@@ -202,4 +214,46 @@ mod tests {
         assert_eq!(chain.len(), 2);
         assert!(!chain.is_empty());
     }
+
+    // ── Gemini-first chain ordering ───────────────────────────────────────────
+
+    #[tokio::test]
+    async fn gemini_first_in_single_provider_chain() {
+        // When we build a chain with a mock "gemini" provider first, it should
+        // be used before any fallback.
+        let chain = ProviderChain::from_providers(vec![
+            Box::new(MockProvider {
+                name: "gemini",
+                response: Ok("from gemini".into()),
+                available: true,
+            }),
+            Box::new(MockProvider {
+                name: "openai",
+                response: Ok("from openai".into()),
+                available: true,
+            }),
+        ]);
+        let result = chain.complete(&test_request()).await.unwrap();
+        assert_eq!(result, "from gemini");
+        // Confirm order: first provider name is "gemini"
+        assert_eq!(chain.providers[0].name(), "gemini");
+    }
+
+    #[tokio::test]
+    async fn gemini_failure_falls_back_to_openai() {
+        let chain = ProviderChain::from_providers(vec![
+            Box::new(MockProvider {
+                name: "gemini",
+                response: Err("subprocess timed out".into()),
+                available: true,
+            }),
+            Box::new(MockProvider {
+                name: "openai",
+                response: Ok("from openai".into()),
+                available: true,
+            }),
+        ]);
+        let result = chain.complete(&test_request()).await.unwrap();
+        assert_eq!(result, "from openai");
+    }
 }

crates/noxa-mcp/src/server.rs

@@ -89,7 +89,7 @@ impl NoxaMcp {
 
         let chain = noxa_llm::ProviderChain::default().await;
         let llm_chain = if chain.is_empty() {
-            warn!("no LLM providers available -- extract/summarize tools will fail");
+            warn!("no LLM providers available (gemini CLI, OPENAI_API_KEY, ANTHROPIC_API_KEY) -- extract/summarize tools will fail");
             None
         } else {
             info!(providers = chain.len(), "LLM provider chain ready");
@@ -334,7 +334,7 @@ impl NoxaMcp {
         // No local LLM — fall back to cloud API directly
         if self.llm_chain.is_none() {
             let cloud = self.cloud.as_ref().ok_or(
-                "No LLM providers available. Set OPENAI_API_KEY, ANTHROPIC_API_KEY, or NOXA_API_KEY for cloud fallback.",
+                "No LLM providers available. Install the gemini CLI, set OPENAI_API_KEY, ANTHROPIC_API_KEY, or NOXA_API_KEY for cloud fallback.",
             )?;
             let mut body = json!({"url": params.url});
             if let Some(ref schema) = params.schema {
@@ -387,7 +387,7 @@ impl NoxaMcp {
         // No local LLM — fall back to cloud API directly
         if self.llm_chain.is_none() {
             let cloud = self.cloud.as_ref().ok_or(
-                "No LLM providers available. Set OPENAI_API_KEY, ANTHROPIC_API_KEY, or NOXA_API_KEY for cloud fallback.",
+                "No LLM providers available. Install the gemini CLI, set OPENAI_API_KEY, ANTHROPIC_API_KEY, or NOXA_API_KEY for cloud fallback.",
             )?;
             let mut body = json!({"url": params.url});
             if let Some(sentences) = params.max_sentences {