fix: prevent AI matching write timeout (#197)

server/cmd/api/server.go

@@ -54,6 +54,12 @@ var (
 	}
 )
 
+// The synchronous Admin AI endpoints allow a provider timeout of up to 600
+// seconds and the browser waits 610 seconds. Keep the HTTP server alive a
+// little longer so it can return the domain response instead of truncating
+// the connection and surfacing a proxy-level 502.
+const minimumAPIWriteTimeout = 620 * time.Second
+
 var AppRouters = make([]func(), 0)
 
 func init() {
@@ -125,11 +131,15 @@ func run() error {
 		)
 	}
 
+	writeTimeout, err := validatedAPIWriteTimeout(config.ApplicationConfig.WriterTimeout)
+	if err != nil {
+		return err
+	}
 	srv := &http.Server{
 		Addr:         fmt.Sprintf("%s:%d", config.ApplicationConfig.Host, config.ApplicationConfig.Port),
 		Handler:      sdk.Runtime.GetEngine(),
 		ReadTimeout:  time.Duration(config.ApplicationConfig.ReadTimeout) * time.Second,
-		WriteTimeout: time.Duration(config.ApplicationConfig.WriterTimeout) * time.Second,
+		WriteTimeout: writeTimeout,
 	}
 
 	go func() {
@@ -193,6 +203,14 @@ func run() error {
 	return nil
 }
 
+func validatedAPIWriteTimeout(seconds int) (time.Duration, error) {
+	timeout := time.Duration(seconds) * time.Second
+	if timeout < minimumAPIWriteTimeout {
+		return 0, fmt.Errorf("application writetimeout must be at least %s for synchronous AI requests", minimumAPIWriteTimeout)
+	}
+	return timeout, nil
+}
+
 type policyLoader interface {
 	LoadPolicy() error
 }

server/cmd/api/server_timeout_test.go

@@ -0,0 +1,19 @@
+package api
+
+import (
+	"testing"
+	"time"
+)
+
+func TestValidatedAPIWriteTimeoutProtectsSynchronousAIRequests(t *testing.T) {
+	if _, err := validatedAPIWriteTimeout(2); err == nil {
+		t.Fatal("two-second write timeout must be rejected")
+	}
+	got, err := validatedAPIWriteTimeout(620)
+	if err != nil {
+		t.Fatalf("620-second write timeout should be accepted: %v", err)
+	}
+	if got != 620*time.Second {
+		t.Fatalf("write timeout = %s, want 620s", got)
+	}
+}