diff --git a/internal/registry/model_definitions.go b/internal/registry/model_definitions.go
index 8896a9dfdb..2c16d5bc0d 100644
--- a/internal/registry/model_definitions.go
+++ b/internal/registry/model_definitions.go
@@ -365,6 +365,19 @@ func GetGitHubCopilotModels() []*ModelInfo {
 			SupportedEndpoints:  []string{"/responses"},
 			Thinking:            &ThinkingSupport{Levels: []string{"none", "low", "medium", "high", "xhigh"}},
 		},
+		{
+			ID:                  "gpt-5.4",
+			Object:              "model",
+			Created:             now,
+			OwnedBy:             "github-copilot",
+			Type:                "github-copilot",
+			DisplayName:         "GPT-5.4",
+			Description:         "OpenAI GPT-5.4 via GitHub Copilot",
+			ContextLength:       200000,
+			MaxCompletionTokens: 32768,
+			SupportedEndpoints:  []string{"/responses"},
+			Thinking:            &ThinkingSupport{Levels: []string{"none", "low", "medium", "high", "xhigh"}},
+		},
 		{
 			ID:                  "claude-haiku-4.5",
 			Object:              "model",
diff --git a/internal/runtime/executor/github_copilot_executor.go b/internal/runtime/executor/github_copilot_executor.go
index b86146a31a..a5770e078f 100644
--- a/internal/runtime/executor/github_copilot_executor.go
+++ b/internal/runtime/executor/github_copilot_executor.go
@@ -577,9 +577,33 @@ func useGitHubCopilotResponsesEndpoint(sourceFormat sdktranslator.Format, model
 		return true
 	}
 	baseModel := strings.ToLower(thinking.ParseSuffix(model).ModelName)
+	if info := registry.GetGlobalRegistry().GetModelInfo(baseModel, githubCopilotAuthType); info != nil {
+		return len(info.SupportedEndpoints) > 0 && !containsEndpoint(info.SupportedEndpoints, githubCopilotChatPath) && containsEndpoint(info.SupportedEndpoints, githubCopilotResponsesPath)
+	}
+	if info := lookupGitHubCopilotStaticModelInfo(baseModel); info != nil {
+		return len(info.SupportedEndpoints) > 0 && !containsEndpoint(info.SupportedEndpoints, githubCopilotChatPath) && containsEndpoint(info.SupportedEndpoints, githubCopilotResponsesPath)
+	}
 	return strings.Contains(baseModel, "codex")
 }
 
+func lookupGitHubCopilotStaticModelInfo(model string) *registry.ModelInfo {
+	for _, info := range registry.GetStaticModelDefinitionsByChannel(githubCopilotAuthType) {
+		if info != nil && strings.EqualFold(info.ID, model) {
+			return info
+		}
+	}
+	return nil
+}
+
+func containsEndpoint(endpoints []string, endpoint string) bool {
+	for _, item := range endpoints {
+		if item == endpoint {
+			return true
+		}
+	}
+	return false
+}
+
 // flattenAssistantContent converts assistant message content from array format
 // to a joined string. GitHub Copilot requires assistant content as a string;
 // sending it as an array causes Claude models to re-answer all previous prompts.
diff --git a/internal/runtime/executor/github_copilot_executor_test.go b/internal/runtime/executor/github_copilot_executor_test.go
index 66d5ce924f..dfc332f24d 100644
--- a/internal/runtime/executor/github_copilot_executor_test.go
+++ b/internal/runtime/executor/github_copilot_executor_test.go
@@ -5,6 +5,7 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/router-for-me/CLIProxyAPI/v6/internal/registry"
 	sdktranslator "github.com/router-for-me/CLIProxyAPI/v6/sdk/translator"
 	"github.com/tidwall/gjson"
 )
@@ -70,6 +71,29 @@ func TestUseGitHubCopilotResponsesEndpoint_CodexModel(t *testing.T) {
 	}
 }
 
+func TestUseGitHubCopilotResponsesEndpoint_RegistryResponsesOnlyModel(t *testing.T) {
+	t.Parallel()
+	if !useGitHubCopilotResponsesEndpoint(sdktranslator.FromString("openai"), "gpt-5.4") {
+		t.Fatal("expected responses-only registry model to use /responses")
+	}
+}
+
+func TestUseGitHubCopilotResponsesEndpoint_DynamicRegistryWinsOverStatic(t *testing.T) {
+	t.Parallel()
+
+	reg := registry.GetGlobalRegistry()
+	clientID := "github-copilot-test-client"
+	reg.RegisterClient(clientID, "github-copilot", []*registry.ModelInfo{{
+		ID:                 "gpt-5.4",
+		SupportedEndpoints: []string{"/chat/completions", "/responses"},
+	}})
+	defer reg.UnregisterClient(clientID)
+
+	if useGitHubCopilotResponsesEndpoint(sdktranslator.FromString("openai"), "gpt-5.4") {
+		t.Fatal("expected dynamic registry definition to take precedence over static fallback")
+	}
+}
+
 func TestUseGitHubCopilotResponsesEndpoint_DefaultChat(t *testing.T) {
 	t.Parallel()
 	if useGitHubCopilotResponsesEndpoint(sdktranslator.FromString("openai"), "claude-3-5-sonnet") {