feat: support GOOSE_OAUTH_CALLBACK_PORT for stable OAuth redirect_uri (#9209)

Signed-off-by: Douwe Osinga <douwe@squareup.com>
Co-authored-by: Douwe Osinga <douwe@squareup.com>

crates/goose/src/oauth/mod.rs

@@ -76,7 +76,11 @@ pub async fn oauth_flow(
         .route("/oauth_callback", get(handler))
         .with_state(app_state);
 
-    let addr = SocketAddr::from(([127, 0, 0, 1], 0));
+    let port: u16 = std::env::var("GOOSE_OAUTH_CALLBACK_PORT")
+        .ok()
+        .and_then(|p| p.parse().ok())
+        .unwrap_or(0);
+    let addr = SocketAddr::from(([127, 0, 0, 1], port));
     let listener = tokio::net::TcpListener::bind(addr).await?;
     let used_addr = listener.local_addr()?;
     tokio::spawn(async move {

crates/goose/src/providers/oauth.rs

@@ -341,7 +341,10 @@ impl OAuthFlow {
 
         // If no port is specified (or port is explicitly 0), let the OS assign one
         // Otherwise, use the requested port
-        let bind_port = requested_port.unwrap_or(0);
+        let env_port: Option<u16> = std::env::var("GOOSE_OAUTH_CALLBACK_PORT")
+            .ok()
+            .and_then(|p| p.parse().ok());
+        let bind_port = requested_port.or(env_port).unwrap_or(0);
         let addr = SocketAddr::from(([127, 0, 0, 1], bind_port));
         let listener = tokio::net::TcpListener::bind(addr).await?;