feat: add temperature env var (#2083)

crates/goose/Cargo.toml

@@ -83,6 +83,7 @@ serial_test = "3.2.0"
 mockall = "0.13.1"
 wiremock = "0.6.0"
 tokio = { version = "1.43", features = ["full"] }
+temp-env = "0.3.6"
 
 [[example]]
 name = "agent"

crates/goose/src/model.rs

@@ -44,11 +44,15 @@ impl ModelConfig {
 
         let toolshim_model = std::env::var("GOOSE_TOOLSHIM_OLLAMA_MODEL").ok();
 
+        let temperature = std::env::var("GOOSE_TEMPERATURE")
+            .ok()
+            .and_then(|val| val.parse::<f32>().ok());
+
         Self {
             model_name,
             tokenizer_name: tokenizer_name.to_string(),
             context_limit,
-            temperature: None,
+            temperature,
             max_tokens: None,
             toolshim,
             toolshim_model,
@@ -182,4 +186,27 @@ mod tests {
             .with_toolshim_model(Some("mistral-nemo".to_string()));
         assert_eq!(config.toolshim_model, Some("mistral-nemo".to_string()));
     }
+
+    #[test]
+    fn test_model_config_temp_env_var() {
+        use temp_env::with_var;
+
+        with_var("GOOSE_TEMPERATURE", Some("0.128"), || {
+            let config = ModelConfig::new("test-model".to_string());
+            assert_eq!(config.temperature, Some(0.128));
+        });
+
+        with_var("GOOSE_TEMPERATURE", Some("notanum"), || {
+            let config = ModelConfig::new("test-model".to_string());
+            assert_eq!(config.temperature, None);
+        });
+
+        with_var("GOOSE_TEMPERATURE", Some(""), || {
+            let config = ModelConfig::new("test-model".to_string());
+            assert_eq!(config.temperature, None);
+        });
+
+        let config = ModelConfig::new("test-model".to_string());
+        assert_eq!(config.temperature, None);
+    }
 }