feat(providers): add LongCat model provider support (#1317)

* feat(providers): add LongCat model provider support

Add LongCat as an OpenAI-compatible provider with base URL
https://api.longcat.chat/openai and default model LongCat-Flash-Thinking.
Includes provider config, migration, factory routing, example config,
tests, and README entries for all 6 locales.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix(providers): address LongCat review feedback

- Add dedicated factory routing test for LongCat provider
- Add longcat to DefaultAPIBase test coverage
- Set default api_base in example config providers section

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* test(providers): add ResolveProviderSelection tests for LongCat

Add two test cases to TestResolveProviderSelection:
- Explicit provider selection with api_base default and proxy wiring
- Fallback inference from model name with api_base default

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

pkg/config/config.go

@@ -527,6 +527,7 @@ type ProvidersConfig struct {
 	Mistral       ProviderConfig       `json:"mistral"`
 	Avian         ProviderConfig       `json:"avian"`
 	Minimax       ProviderConfig       `json:"minimax"`
+	LongCat       ProviderConfig       `json:"longcat"`
 }
 
 // IsEmpty checks if all provider configs are empty (no API keys or API bases set)
@@ -553,7 +554,8 @@ func (p ProvidersConfig) IsEmpty() bool {
 		p.Qwen.APIKey == "" && p.Qwen.APIBase == "" &&
 		p.Mistral.APIKey == "" && p.Mistral.APIBase == "" &&
 		p.Avian.APIKey == "" && p.Avian.APIBase == "" &&
-		p.Minimax.APIKey == "" && p.Minimax.APIBase == ""
+		p.Minimax.APIKey == "" && p.Minimax.APIBase == "" &&
+		p.LongCat.APIKey == "" && p.LongCat.APIBase == ""
 }
 
 // MarshalJSON implements custom JSON marshaling for ProvidersConfig

pkg/config/defaults.go

@@ -355,6 +355,14 @@ func DefaultConfig() *Config {
 				APIKey:    "",
 			},
 
+			// LongCat - https://longcat.chat/platform
+			{
+				ModelName: "LongCat-Flash-Thinking",
+				Model:     "longcat/LongCat-Flash-Thinking",
+				APIBase:   "https://api.longcat.chat/openai",
+				APIKey:    "",
+			},
+
 			// VLLM (local) - http://localhost:8000
 			{
 				ModelName: "local-model",

pkg/config/migration.go

@@ -407,6 +407,23 @@ func ConvertProvidersToModelList(cfg *Config) []ModelConfig {
 				}, true
 			},
 		},
+		{
+			providerNames: []string{"longcat"},
+			protocol:      "longcat",
+			buildConfig: func(p ProvidersConfig) (ModelConfig, bool) {
+				if p.LongCat.APIKey == "" && p.LongCat.APIBase == "" {
+					return ModelConfig{}, false
+				}
+				return ModelConfig{
+					ModelName:      "longcat",
+					Model:          "longcat/LongCat-Flash-Thinking",
+					APIKey:         p.LongCat.APIKey,
+					APIBase:        p.LongCat.APIBase,
+					Proxy:          p.LongCat.Proxy,
+					RequestTimeout: p.LongCat.RequestTimeout,
+				}, true
+			},
+		},
 	}
 
 	// Process each provider migration

pkg/config/migration_test.go

@@ -162,14 +162,15 @@ func TestConvertProvidersToModelList_AllProviders(t *testing.T) {
 			Qwen:          ProviderConfig{APIKey: "key17"},
 			Mistral:       ProviderConfig{APIKey: "key18"},
 			Avian:         ProviderConfig{APIKey: "key19"},
+			LongCat:       ProviderConfig{APIKey: "key-longcat"},
 		},
 	}
 
 	result := ConvertProvidersToModelList(cfg)
 
-	// All 21 providers should be converted
-	if len(result) != 21 {
-		t.Errorf("len(result) = %d, want 21", len(result))
+	// All 22 providers should be converted
+	if len(result) != 22 {
+		t.Errorf("len(result) = %d, want 22", len(result))
 	}
 }