diff --git a/Cargo.lock b/Cargo.lock
index 49104b22d2..de6b99c01c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -835,6 +835,7 @@ dependencies = [
  "serde_json",
  "serde_yaml",
  "sha2 0.11.0",
+ "temp-env",
  "tempfile",
  "tokio",
  "tracing",
@@ -2177,7 +2178,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ccc2776f0c61eca1ca32528f85548abd1a4be8fb53d1b21c013e4f18da1e7090"
 dependencies = [
  "data-encoding",
- "syn 1.0.109",
+ "syn 2.0.117",
 ]
 
 [[package]]
@@ -8714,6 +8715,15 @@ dependencies = [
  "xattr",
 ]
 
+[[package]]
+name = "temp-env"
+version = "0.3.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "96374855068f47402c3121c6eed88d29cb1de8f3ab27090e273e420bdabcf050"
+dependencies = [
+ "parking_lot",
+]
+
 [[package]]
 name = "tempfile"
 version = "3.27.0"
diff --git a/crates/buzz-agent/Cargo.toml b/crates/buzz-agent/Cargo.toml
index 7889ad34a7..0fa69a222d 100644
--- a/crates/buzz-agent/Cargo.toml
+++ b/crates/buzz-agent/Cargo.toml
@@ -55,3 +55,4 @@ hex = { workspace = true }
 serde = { workspace = true }
 sha2 = { workspace = true }
 tempfile = "3"
+temp-env = "0.3"
diff --git a/crates/buzz-agent/src/config.rs b/crates/buzz-agent/src/config.rs
index a0e64f1a9d..852e06051b 100644
--- a/crates/buzz-agent/src/config.rs
+++ b/crates/buzz-agent/src/config.rs
@@ -791,7 +791,9 @@ impl Config {
                     env("OPENAI_COMPAT_MODEL").as_deref(),
                 )
                 .ok_or_else(|| "config: OPENAI_COMPAT_MODEL required".to_string())?,
-                env_or("OPENAI_COMPAT_BASE_URL", "https://api.openai.com/v1"),
+                env("OPENAI_COMPAT_BASE_URL")
+                    .or_else(|| env("OPENAI_BASE_URL"))
+                    .unwrap_or_else(|| "https://api.openai.com/v1".into()),
                 parse_openai_api(env("OPENAI_COMPAT_API").as_deref())?,
             ),
             Provider::Databricks | Provider::DatabricksV2 => (
@@ -2751,4 +2753,67 @@ mod tests {
         let err = resolve_provider(Some("openrouter"), None, None, None).unwrap_err();
         assert!(err.contains("OPENROUTER_API_KEY"));
     }
+
+    #[test]
+    fn base_url_prefers_compat_over_generic() {
+        temp_env::with_vars(
+            [
+                ("BUZZ_AGENT_PROVIDER", Some("openai")),
+                ("OPENAI_COMPAT_API_KEY", Some("sk-test")),
+                ("OPENAI_COMPAT_MODEL", Some("gpt-4")),
+                ("OPENAI_COMPAT_BASE_URL", Some("https://custom-openai.local/v1")),
+                ("OPENAI_BASE_URL", Some("https://generic-openai.local/v1")),
+            ],
+            || {
+                let config = Config::from_env().unwrap();
+                assert_eq!(
+                    config.base_url,
+                    "https://custom-openai.local/v1",
+                    "specific OPENAI_COMPAT_BASE_URL should win over generic OPENAI_BASE_URL"
+                );
+            },
+        );
+    }
+
+    #[test]
+    fn base_url_falls_back_to_generic_when_compat_unset() {
+        temp_env::with_vars(
+            [
+                ("BUZZ_AGENT_PROVIDER", Some("openai")),
+                ("OPENAI_COMPAT_API_KEY", Some("sk-test")),
+                ("OPENAI_COMPAT_MODEL", Some("gpt-4")),
+                ("OPENAI_COMPAT_BASE_URL", None),
+                ("OPENAI_BASE_URL", Some("https://generic-openai.local/v1")),
+            ],
+            || {
+                let config = Config::from_env().unwrap();
+                assert_eq!(
+                    config.base_url,
+                    "https://generic-openai.local/v1",
+                    "OPENAI_BASE_URL should be used when OPENAI_COMPAT_BASE_URL is unset"
+                );
+            },
+        );
+    }
+
+    #[test]
+    fn base_url_defaults_when_none_set() {
+        temp_env::with_vars(
+            [
+                ("BUZZ_AGENT_PROVIDER", Some("openai")),
+                ("OPENAI_COMPAT_API_KEY", Some("sk-test")),
+                ("OPENAI_COMPAT_MODEL", Some("gpt-4")),
+                ("OPENAI_COMPAT_BASE_URL", None),
+                ("OPENAI_BASE_URL", None),
+            ],
+            || {
+                let config = Config::from_env().unwrap();
+                assert_eq!(
+                    config.base_url,
+                    "https://api.openai.com/v1",
+                    "should default when neither env var is set"
+                );
+            },
+        );
+    }
 }