From cd2b3cea8acab270ea4f18823c0a905192a14e94 Mon Sep 17 00:00:00 2001
From: David Gageot <david.gageot@docker.com>
Date: Wed, 11 Feb 2026 18:19:39 +0100
Subject: [PATCH] List valid versions in unsupported config version error

Assisted-By: cagent
---
 pkg/config/config.go          |  6 ++++--
 pkg/config/validation_test.go | 18 ++++++++++++++++++
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/pkg/config/config.go b/pkg/config/config.go
index 6d573ce4a..91e603f63 100644
--- a/pkg/config/config.go
+++ b/pkg/config/config.go
@@ -5,6 +5,7 @@ import (
 	"context"
 	"fmt"
 	"log/slog"
+	"maps"
 	"net/url"
 	"slices"
 	"strings"
@@ -73,9 +74,10 @@ func CheckRequiredEnvVars(ctx context.Context, cfg *latest.Config, modelsGateway
 }
 
 func parseCurrentVersion(data []byte, version string) (any, error) {
-	parser, found := Parsers()[version]
+	parsers := Parsers()
+	parser, found := parsers[version]
 	if !found {
-		return nil, fmt.Errorf("unsupported config version: %v", version)
+		return nil, fmt.Errorf("unsupported config version: %v (valid versions: %s)", version, strings.Join(slices.Sorted(maps.Keys(parsers)), ", "))
 	}
 	return parser(data)
 }
diff --git a/pkg/config/validation_test.go b/pkg/config/validation_test.go
index 6de1983e4..fe5e409e1 100644
--- a/pkg/config/validation_test.go
+++ b/pkg/config/validation_test.go
@@ -4,6 +4,7 @@ import (
 	"path/filepath"
 	"testing"
 
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
@@ -71,6 +72,23 @@ func TestValidationErrors(t *testing.T) {
 	}
 }
 
+func TestLoadConfig_UnsupportedVersion(t *testing.T) {
+	t.Parallel()
+
+	cfg := `version: "99"
+agents:
+  root:
+    model: openai/gpt-4
+`
+	_, err := Load(t.Context(), NewBytesSource("test", []byte(cfg)))
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "unsupported config version: 99")
+	assert.Contains(t, err.Error(), "valid versions")
+	// Check that at least some known versions are listed
+	assert.Contains(t, err.Error(), "1")
+	assert.Contains(t, err.Error(), "2")
+}
+
 func TestValidSkillsConfiguration(t *testing.T) {
 	t.Parallel()